@article {2542, title = {DDX24 is required for muscle fiber organization and the suppression of wound-induced Wnt activity necessary for pole re-establishment during planarian regeneration.}, journal = {Dev Biol}, volume = {488}, year = {2022}, month = {2022 May 04}, pages = {11-29}, abstract = {

Planarians have a remarkable ability to undergo whole-body regeneration. Successful regeneration outcome is determined by processes like polarity establishment at the wound site, which is followed by pole (organizer) specification. Interestingly, these determinants are almost exclusively expressed by muscles in these animals. However, the molecular toolkit that enables the functional versatility of planarian muscles remains poorly understood. Here we report that SMED_DDX24, a D-E-A-D Box RNA helicase, is necessary for planarian survival and regeneration. We found that DDX24 is enriched in muscles and its knockdown disrupts muscle fiber organization. This leads to defective pole specification, which in turn results in misregulation of many positional control genes specifically during regeneration. ddx24 RNAi also upregulates wound-induced Wnt signalling. Suppressing this ectopic Wnt activity rescues the knockdown phenotype by enabling better anterior pole regeneration. To summarize, our work highlights the role of an RNA helicase in muscle fiber organization, and modulating amputation-induced wnt levels, both of which seem critical for pole re-organization, thereby regulating whole-body regeneration.

}, issn = {1095-564X}, doi = {10.1016/j.ydbio.2022.04.011}, author = {Sarkar, Souradeep R and Dubey, Vinay Kumar and Jahagirdar, Anusha and Lakshmanan, Vairavan and Haroon, Mohamed Mohamed and Sowndarya, Sai and Sowdhamini, Ramanathan and Palakodeti, Dasaradhi} } @article {2424, title = {Flow Cytometry Analysis of Planarian Stem Cells Using DNA and Mitochondrial Dyes.}, journal = {Bio Protoc}, volume = {12}, year = {2022}, month = {2022 Jan 20}, pages = {e4299}, abstract = {

Planarians are free-living flatworms that emerged as a crucial model system to understand regeneration and stem cell biology. The ability to purify neoblasts, the adult stem cell population of planaria, through fluorescence-activated cell sorting (FACS) has tremendously increased our understanding of pluripotency, specialization, and heterogeneity. To date, the FACS-based purification methods for neoblasts relied on nuclear dyes that discriminate proliferating cells (\>2N), as neoblasts are the only dividing somatic cells. However, this method does not distinguish the functional states within the neoblast population. Our work has shown that among the neoblasts, the pluripotent stem cells (PSCs) are associated with low mitochondrial content and this property could be leveraged for purification of the PSC-enriched population. Using the mitochondrial dye MitoTracker Green (MTG) and the nuclear dye SiR-DNA, we have described a method for isolation of PSCs that are viable and compatible with downstream experiments, such as transplantation and cell culture. In this protocol, we provide a detailed description for sample preparation and FACS gating for neoblast isolation in planaria.

}, issn = {2331-8325}, doi = {10.21769/BioProtoc.4299}, author = {Haroon, Mohamed Mohamed and Vemula, Praveen Kumar and Palakodeti, Dasaradhi} } @article {3346, title = {Function of FMRP Domains in Regulating Distinct Roles of Neuronal Protein Synthesis.}, journal = {Mol Neurobiol}, volume = {59}, year = {2022}, month = {2022 Dec}, pages = {7370-7392}, abstract = {

The Fragile-X Mental Retardation Protein (FMRP) is an RNA binding protein that regulates translation of mRNAs essential for synaptic development and plasticity. FMRP interacts with a specific set of mRNAs, aids in their microtubule-dependent transport and regulates their translation through its association with ribosomes. However, the biochemical role of FMRP{\textquoteright}s domains in forming neuronal granules and associating with microtubules and ribosomes is currently undefined. We report that the C-terminus domain of FMRP is sufficient to bind to ribosomes akin to the full-length protein. Furthermore, the C-terminus domain alone is essential and responsible for FMRP-mediated neuronal translation repression. However, dendritic distribution of FMRP and its microtubule association is favored by the synergistic combination of FMRP domains rather than individual domains. Interestingly, we show that the phosphorylation of hFMRP at Serine-500 is important in modulating the dynamics of translation by controlling ribosome association. This is a fundamental mechanism governing the size and number of FMRP puncta that contain actively translating ribosomes. Finally through the use of pathogenic mutations, we emphasize the hierarchical contribution of FMRP{\textquoteright}s domains in translation regulation.

}, keywords = {Fragile X Mental Retardation Protein, Fragile X Syndrome, Humans, Microtubules, Neurons, Protein Biosynthesis, Ribosomes, RNA, Messenger}, issn = {1559-1182}, doi = {10.1007/s12035-022-03049-1}, author = {D{\textquoteright}Souza, Michelle Ninochka and Ramakrishna, Sarayu and Radhakrishna, Bindushree K and Jhaveri, Vishwaja and Ravindran, Sreenath and Yeramala, Lahari and Nair, Deepak and Palakodeti, Dasaradhi and Muddashetty, Ravi S} } @article {3347, title = {S. mediterranea ETS-1 regulates the function of cathepsin-positive cells and the epidermal lineage landscape via basement membrane remodeling.}, journal = {J Cell Sci}, volume = {135}, year = {2022}, month = {2022 10 15}, abstract = {

Extracellular matrix (ECM) is an important component of stem cell niche. Remodeling of ECM mediated by ECM regulators, such as matrix metalloproteinases (MMPs) plays a vital role in stem cell function. However, the mechanisms that modulate the function of ECM regulators in the stem cell niche are understudied. Here, we explored the role of the transcription factor (TF) ETS-1, which is expressed in the cathepsin-positive cell population, in regulating the expression of the ECM regulator, mt-mmpA, thereby modulating basement membrane thickness. In planarians, the basement membrane around the gut/inner parenchyma is thought to act as a niche for pluripotent stem cells. It has been shown that the early epidermal progenitors migrate outwards from this region and progressively differentiate to maintain the terminal epidermis. Our data shows that thickening of the basement membrane in the absence of ets-1 results in defective migration of stem cell progeny. Furthermore, the absence of ets-1 leads to a defective epidermal progenitor landscape, despite its lack of expression in those cell types. Together, our results demonstrate the active role of ECM remodeling in regulating tissue homeostasis and regeneration in the planarian Schmidtea mediterranea. This article has an associated First Person interview with one of the co-first authors of the paper.

}, keywords = {Animals, Basement Membrane, Cathepsins, Cell Differentiation, Epidermis, Humans, Matrix Metalloproteinases, Mediterranea, Planarians, Transcription Factors}, issn = {1477-9137}, doi = {10.1242/jcs.259900}, author = {Dubey, Vinay Kumar and Sarkar, Souradeep R and Lakshmanan, Vairavan and Dalmeida, Rimple and Gulyani, Akash and Palakodeti, Dasaradhi} } @article {2505, title = {The story of rRNA expansion segments: Finding functionality amidst diversity.}, journal = {Wiley Interdiscip Rev RNA}, year = {2022}, month = {2022 Apr 15}, pages = {e1732}, abstract = {

Expansion segments (ESs) are multinucleotide insertions present across phyla at specific conserved positions in eukaryotic rRNAs. ESs are generally absent in bacterial rRNAs with some exceptions, while the archaeal rRNAs have microexpansions at regions that coincide with those of eukaryotic ESs. Although there is an increasing prominence of ribosomes, especially the ribosomal proteins, in fine-tuning gene expression through translation regulation, the role of rRNA ESs is relatively underexplored. While rRNAs have been established as the major catalytic hub in ribosome function, the presence of ESs widens their scope as a species-specific regulatory hub of protein synthesis. In this comprehensive review, we have elaborately discussed the current understanding of the functional aspects of rRNA ESs of cytoplasmic eukaryotic ribosomes and discuss their past, present, and future. This article is categorized under: RNA Structure and Dynamics \> Influence of RNA Structure in Biological Systems Translation \> Ribosome Structure/Function Translation \> Regulation.

}, issn = {1757-7012}, doi = {10.1002/wrna.1732}, author = {Hariharan, Nivedita and Ghosh, Sumana and Palakodeti, Dasaradhi} } @article {2362, title = {Astrocytic reactivity triggered by defective autophagy and metabolic failure causes neurotoxicity in frontotemporal dementia type 3.}, journal = {Stem Cell Reports}, volume = {16}, year = {2021}, month = {2021 Nov 09}, pages = {2736-2751}, abstract = {

Frontotemporal dementia type 3 (FTD3), caused by a point mutation in the charged multivesicular body protein 2B (CHMP2B), affects mitochondrial ultrastructure and the endolysosomal pathway in neurons. To dissect the astrocyte-specific impact of mutant CHMP2B expression, we generated astrocytes from human induced pluripotent stem cells (hiPSCs) and confirmed our findings in CHMP2B mutant mice. Our data provide mechanistic insights into how defective autophagy causes perturbed mitochondrial dynamics with impaired glycolysis, increased reactive oxygen species, and elongated mitochondrial morphology, indicating increased mitochondrial fusion in FTD3 astrocytes. This shift in astrocyte homeostasis triggers a reactive astrocyte phenotype and increased release of toxic cytokines, which accumulate in nuclear factor kappa b (NF-κB) pathway activation with increased production of CHF, LCN2, and C3 causing neurodegeneration.

}, issn = {2213-6711}, doi = {10.1016/j.stemcr.2021.09.013}, author = {Chandrasekaran, Abinaya and Dittlau, Katarina Stoklund and Corsi, Giulia I and Haukedal, Henriette and Doncheva, Nadezhda T and Ramakrishna, Sarayu and Ambardar, Sheetal and Salcedo, Claudia and Schmidt, Sissel I and Zhang, Yu and Cirera, Susanna and Pihl, Maria and Schmid, Benjamin and Nielsen, Troels Tolstrup and Nielsen, J{\o}rgen E and Kolko, Miriam and Kobol{\'a}k, Julianna and Dinny{\'e}s, Andr{\'a}s and Hyttel, Poul and Palakodeti, Dasaradhi and Gorodkin, Jan and Muddashetty, Ravi S and Meyer, Morten and Aldana, Blanca I and Freude, Kristine K} } @article {2207, title = {Comprehensive annotation and characterization of planarian tRNA and tRNA-derived fragments (tRFs).}, journal = {RNA}, year = {2021}, month = {2021 Jan 14}, abstract = {

tRNA-derived fragments (tRFs) have recently gained a lot of scientific interest due to their diverse regulatory roles in several cellular processes. However, their function in dynamic biological process such as development and regeneration remains unexplored. Here, we show that tRFs are dynamically expressed during planarian regeneration suggesting a possible role for these small RNAs in the regulation of regeneration. In order to characterise planarian tRFs, we first annotated 457 tRNAs in S.mediterranea combining two tRNA prediction algorithms. Annotation of tRNAs facilitated the identification of three main species of tRFs in planarians - the shorter tRF-5s and itRFs, and the abundantly expressed 5{\textquoteright}-tsRNAs. Spatial profiling of tRFs in sequential transverse sections of planarians revealed diverse expression patterns of these small RNAs, including those that are enriched in the head and pharyngeal regions. Expression analysis of these tRF species revealed dynamic expression of these small RNAs over the course of regeneration suggesting an important role in planarian anterior and posterior regeneration. Finally, we show that 5{\textquoteright}-tsRNA in planaria interact with all three SMEDWI proteins and an involvement of Ago1 in the processing of itRFs. In summary, our findings implicate a novel role for tRFs in planarian regeneration, highlighting their importance in regulating complex systemic processes. Our study adds to the catalogue of post-transcriptional regulatory systems in planarian, providing valuable insights on the biogenesis and the function of tRFs in neoblasts and planarian regeneration.

}, issn = {1469-9001}, doi = {10.1261/rna.077701.120}, author = {Lakshmanan, Vairavan and T N, Sujith and Bansal, Dhiru and Padubidri, Shivaprasad V and Palakodeti, Dasaradhi and Krishna, Srikar} } @article {2273, title = {Discovery of a body-wide photosensory array that matures in an adult-like animal and mediates eye-brain-independent movement and arousal.}, journal = {Proc Natl Acad Sci U S A}, volume = {118}, year = {2021}, month = {2021 May 18}, abstract = {

The ability to respond to light has profoundly shaped life. Animals with eyes overwhelmingly rely on their visual circuits for mediating light-induced coordinated movements. Building on previously reported behaviors, we report the discovery of an organized, eye-independent (extraocular), body-wide photosensory framework that allows even a head-removed animal to move like an intact animal. Despite possessing sensitive cerebral eyes and a centralized brain that controls most behaviors, head-removed planarians show acute, coordinated ultraviolet-A (UV-A) aversive phototaxis. We find this eye-brain-independent phototaxis is mediated by two noncanonical rhabdomeric opsins, the first known function for this newly classified opsin-clade. We uncover a unique array of dual-opsin-expressing photoreceptor cells that line the periphery of animal body, are proximal to a body-wide nerve net, and mediate UV-A phototaxis by engaging multiple modes of locomotion. Unlike embryonically developing cerebral eyes that are functional when animals hatch, the body-wide photosensory array matures postembryonically in "adult-like animals." Notably, apart from head-removed phototaxis, the body-wide, extraocular sensory organization also impacts physiology of intact animals. Low-dose UV-A, but not visible light (ocular-stimulus), is able to arouse intact worms that have naturally cycled to an inactive/rest-like state. This wavelength selective, low-light arousal of resting animals is noncanonical-opsin dependent but eye independent. Our discovery of an autonomous, multifunctional, late-maturing, organized body-wide photosensory system establishes a paradigm in sensory biology and evolution of light sensing.

}, issn = {1091-6490}, doi = {10.1073/pnas.2021426118}, author = {Shettigar, Nishan and Chakravarthy, Anirudh and Umashankar, Suchitta and Lakshmanan, Vairavan and Palakodeti, Dasaradhi and Gulyani, Akash} } @article {2327, title = {Engineered RNA biosensors enable ultrasensitive SARS-CoV-2 detection in a simple color and luminescence assay.}, journal = {Life Sci Alliance}, volume = {4}, year = {2021}, month = {2021 12}, abstract = {

The continued resurgence of the COVID-19 pandemic with multiple variants underlines the need for diagnostics that are adaptable to the virus. We have developed toehold RNA-based sensors across the SARS-CoV-2 genome for direct and ultrasensitive detection of the virus and its prominent variants. Here, isothermal amplification of a fragment of SARS-CoV-2 RNA coupled with activation of our biosensors leads to a conformational switch in the sensor. This leads to translation of a reporter protein, for example, LacZ or nano-lantern that is easily detected using color/luminescence. By optimizing RNA amplification and biosensor design, we have generated a highly sensitive diagnostic assay that is capable of detecting as low as 100 copies of viral RNA with development of bright color. This is easily visualized by the human eye and quantifiable using spectrophotometry. Finally, this PHAsed NASBA-Translation Optical Method (PHANTOM) using our engineered RNA biosensors efficiently detects viral RNA in patient samples. This work presents a powerful and universally accessible strategy for detecting COVID-19 and variants. This strategy is adaptable to further viral evolution and brings RNA bioengineering center-stage.

}, keywords = {Biosensing Techniques, COVID-19, Humans, Luminescence, Nucleic Acid Amplification Techniques, RNA, RNA, Viral, SARS-CoV-2}, issn = {2575-1077}, doi = {10.26508/lsa.202101213}, author = {Chakravarthy, Anirudh and Nandakumar, Anirudh and George, Geen and Ranganathan, Shyamsundar and Umashankar, Suchitta and Shettigar, Nishan and Palakodeti, Dasaradhi and Gulyani, Akash and Ramesh, Arati} } @article {2323, title = {Genomic characterization and epidemiology of an emerging SARS-CoV-2 variant in Delhi, India.}, journal = {Science}, year = {2021}, month = {2021 Oct 14}, pages = {eabj9932}, abstract = {

Delhi, the national capital of India, has experienced multiple SARS-CoV-2 outbreaks in 2020 and reached population seropositivity of over 50\% by 2021. During April 2021, the city became overwhelmed by COVID-19 cases and fatalities, as a new variant B.1.617.2 (Delta) replaced B.1.1.7 (Alpha). A Bayesian model explains the growth advantage of Delta through a combination of increased transmissibility and reduced sensitivity to immune responses generated against earlier variants (median estimates; {\texttimes}1.5-fold, 20\% reduction). Seropositivity of an employee and family cohort increased from 42\% to 87.5\% between March and July 2021, with 27\% reinfections, as judged by increased antibody concentration after a previous decline. The likely high transmissibility and partial evasion of immunity by the Delta variant contributed to an overwhelming surge in Delhi.

}, issn = {1095-9203}, doi = {10.1126/science.abj9932}, author = {Dhar, Mahesh S and Marwal, Robin and Vs, Radhakrishnan and Ponnusamy, Kalaiarasan and Jolly, Bani and Bhoyar, Rahul C and Sardana, Viren and Naushin, Salwa and Rophina, Mercy and Mellan, Thomas A and Mishra, Swapnil and Whittaker, Charles and Fatihi, Saman and Datta, Meena and Singh, Priyanka and Sharma, Uma and Ujjainiya, Rajat and Bhatheja, Nitin and Divakar, Mohit Kumar and Singh, Manoj K and Imran, Mohamed and Senthivel, Vigneshwar and Maurya, Ranjeet and Jha, Neha and Mehta, Priyanka and A, Vivekanand and Sharma, Pooja and Vr, Arvinden and Chaudhary, Urmila and Soni, Namita and Thukral, Lipi and Flaxman, Seth and Bhatt, Samir and Pandey, Rajesh and Dash, Debasis and Faruq, Mohammed and Lall, Hemlata and Gogia, Hema and Madan, Preeti and Kulkarni, Sanket and Chauhan, Himanshu and Sengupta, Shantanu and Kabra, Sandhya and Gupta, Ravindra K and Singh, Sujeet K and Agrawal, Anurag and Rakshit, Partha and Nandicoori, Vinay and Tallapaka, Karthik Bharadwaj and Sowpati, Divya Tej and Thangaraj, K and Bashyam, Murali Dharan and Dalal, Ashwin and Sivasubbu, Sridhar and Scaria, Vinod and Parida, Ajay and Raghav, Sunil K and Prasad, Punit and Sarin, Apurva and Mayor, Satyajit and Ramakrishnan, Uma and Palakodeti, Dasaradhi and Seshasayee, Aswin Sai Narain and Bhat, Manoj and Shouche, Yogesh and Pillai, Ajay and Dikid, Tanzin and Das, Saumitra and Maitra, Arindam and Chinnaswamy, Sreedhar and Biswas, Nidhan Kumar and Desai, Anita Sudhir and Pattabiraman, Chitra and Manjunatha, M V and Mani, Reeta S and Arunachal Udupi, Gautam and Abraham, Priya and Atul, Potdar Varsha and Cherian, Sarah S} } @article {2311, title = {Glycomic and glycotranscriptomic profiling of mucin-type O-glycans in planarian Schmidtea mediterranea.}, journal = {Glycobiology}, year = {2021}, month = {2021 Sep 06}, abstract = {

O-Glycans on cell surfaces play important roles in cell-cell, cell-matrix, and receptor-ligand interaction. Therefore, glycan-based interactions are important for tissue regeneration and homeostasis. Free-living flatworm Schmidtea mediterranea, because of its robust regenerative potential, is of great interest in the field of stem cell biology and tissue regeneration. Nevertheless, information on the composition and structure of O-glycans in planaria is unknown. Using mass spectrometry and in silico approaches, we characterized the glycome and the related transcriptome of mucin-type O-glycans of planarian S. mediterranea. Mucin-type O-glycans were composed of multiple isomeric, methylated, and unusually extended mono- and di-substituted O-GalNAc structures. Extensions made of hexoses and 3-O methyl hexoses were the glycoforms observed. From glycotranscriptomic analysis, sixty genes belonging to five distinct enzyme classes were identified to be involved in mucin-type O-glycan biosynthesis. These genes shared homology with those in other invertebrate systems. While a majority of the genes involved in mucin-type O-glycan biosynthesis was highly expressed during organogenesis and in differentiated cells, a few select genes in each enzyme class were specifically enriched during early embryogenesis. Our results indicate a unique temporal and spatial role for mucin-type O-glycans during embryogenesis and organogenesis and in adulthood. In summary, this is the first report on O-glycans in planaria. This study expands the structural and biosynthetic possibilities in cellular glycosylation in the invertebrate glycome and provides a framework towards understanding the biological role of mucin-type O-glycans in tissue regeneration using planarians.

}, issn = {1460-2423}, doi = {10.1093/glycob/cwab097}, author = {Subramanian, Sabarinath Peruvemba and Lakshmanan, Vairavan and Palakodeti, Dasaradhi and Subramanian, Ramaswamy} } @article {2242, title = {Mechanical instability of adherens junctions overrides intrinsic quiescence of hair follicle stem cells.}, journal = {Dev Cell}, volume = {56}, year = {2021}, month = {2021 Mar 22}, pages = {761-780.e7}, abstract = {

Vinculin, a mechanotransducer associated with both adherens junctions (AJs) and focal adhesions (FAs), plays a central role in force transmission through cell-cell and cell-substratum contacts. We generated the conditional knockout (cKO) of vinculin in murine skin that results in the loss of bulge stem cell (BuSC) quiescence and promotes continual cycling of the hair follicles. Surprisingly, we find that the AJs in vinculin cKO cells are mechanically weak and impaired in force generation despite increased junctional expression of E-cadherin and α-catenin. Mechanistically, we demonstrate that vinculin functions by keeping α-catenin in a stretched/open conformation, which in turn regulates the retention of YAP1, another potent mechanotransducer and regulator of cell proliferation, at the AJs. Altogether, our data provide mechanistic insights into the hitherto-unexplored regulatory link between the mechanical stability of cell junctions and contact-inhibition-mediated maintenance of BuSC quiescence.

}, issn = {1878-1551}, doi = {10.1016/j.devcel.2021.02.020}, author = {Biswas, Ritusree and Banerjee, Avinanda and Lembo, Sergio and Zhao, Zhihai and Lakshmanan, Vairavan and Lim, Ryan and Le, Shimin and Nakasaki, Manando and Kutyavin, Vassily and Wright, Graham and Palakodeti, Dasaradhi and Ross, Robert S and Jamora, Colin and Vasioukhin, Valeri and Jie, Yan and Raghavan, Srikala} } @article {2274, title = {Mitochondrial state determines functionally divergent stem cell population in planaria.}, journal = {Stem Cell Reports}, volume = {16}, year = {2021}, month = {2021 May 11}, pages = {1302-1316}, abstract = {

Mitochondrial state changes were shown to be critical for stem cell function. However, variation in the mitochondrial content in stem cells and the implication, if any, on differentiation is poorly understood. Here, using cellular and molecular studies, we show that the planarian pluripotent stem cells (PSCs) have low mitochondrial mass compared with their progenitors. Transplantation experiments provided functional validation that neoblasts with low mitochondrial mass are the true PSCs. Further, the mitochondrial mass correlated with OxPhos and inhibiting the transition to OxPhos dependent metabolism in cultured cells resulted in higher PSCs. In summary, we show that low mitochondrial mass is a hallmark of PSCs in planaria and provide a mechanism to isolate live, functionally active, PSCs from different cell cycle stages (G0/G1 and S, G2/M). Our study demonstrates that the change in mitochondrial metabolism, a feature of PSCs is conserved in planaria and highlights its role in organismal regeneration.

}, issn = {2213-6711}, doi = {10.1016/j.stemcr.2021.03.022}, author = {Mohamed Haroon, Mohamed and Lakshmanan, Vairavan and Sarkar, Souradeep R and Lei, Kai and Vemula, Praveen Kumar and Palakodeti, Dasaradhi} } @article {2373, title = {A regulatory network of microRNAs confers lineage commitment during early developmental trajectories of B and T lymphocytes.}, journal = {Proc Natl Acad Sci U S A}, volume = {118}, year = {2021}, month = {2021 11 16}, abstract = {

The commitment of hematopoietic multipotent progenitors (MPPs) toward a particular lineage involves activation of cell type-specific genes and silencing of genes that promote alternate cell fates. Although the gene expression programs of early-B and early-T lymphocyte development are mutually exclusive, we show that these cell types exhibit significantly correlated microRNA (miRNA) profiles. However, their corresponding miRNA targetomes are distinct and predominated by transcripts associated with natural killer, dendritic cell, and myeloid lineages, suggesting that miRNAs function in a cell-autonomous manner. The combinatorial expression of miRNAs miR-186-5p, miR-128-3p, and miR-330-5p in MPPs significantly attenuates their myeloid differentiation potential due to repression of myeloid-associated transcripts. Depletion of these miRNAs caused a pronounced de-repression of myeloid lineage targets in differentiating early-B and early-T cells, resulting in a mixed-lineage gene expression pattern. De novo motif analysis combined with an assay of promoter activities indicates that B as well as T lineage determinants drive the expression of these miRNAs in lymphoid lineages. Collectively, we present a paradigm that miRNAs are conserved between developing B and T lymphocytes, yet they target distinct sets of promiscuously expressed lineage-inappropriate genes to suppress the alternate cell-fate options. Thus, our studies provide a comprehensive compendium of miRNAs with functional implications for B and T lymphocyte development.

}, keywords = {Animals, B-Lymphocytes, Cell Differentiation, Cell Lineage, Gene Expression, Gene Expression Profiling, Gene Regulatory Networks, Hematopoietic Stem Cells, Mice, MicroRNAs, Myeloid Cells, T-Lymphocytes}, issn = {1091-6490}, doi = {10.1073/pnas.2104297118}, author = {Nikhat, Sameena and Yadavalli, Anurupa D and Prusty, Arpita and Narayan, Priyanka K and Palakodeti, Dasaradhi and Murre, Cornelis and Pongubala, Jagan M R} } @article {2372, title = {Ribosomal protein S6 kinase beta-1 gene variants cause hypertrophic cardiomyopathy.}, journal = {J Med Genet}, year = {2021}, month = {2021 Dec 16}, abstract = {

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a genetic heart muscle disease with preserved or increased ejection fraction in the absence of secondary causes. Mutations in the sarcomeric protein-encoding genes predominantly cause HCM. However, relatively little is known about the genetic impact of signalling proteins on HCM.

METHODS AND RESULTS: Here, using exome and targeted sequencing methods, we analysed two independent cohorts comprising 401 Indian patients with HCM and 3521 Indian controls. We identified novel variants in ribosomal protein S6 kinase beta-1 () gene in two unrelated Indian families as a potential candidate gene for HCM. The two unrelated HCM families had the same heterozygous missense S6K1 variant (p.G47W). In a replication association study, we identified two S6K1 heterozygotes variants (p.Q49K and p.Y62H) in the UK Biobank cardiomyopathy cohort (n=190) compared with matched controls (n=16 479). These variants are neither detected in region-specific controls nor in the human population genome data. Additionally, we observed an S6K1 variant (p.P445S) in an Arab patient with HCM. Functional consequences were evaluated using representative S6K1 mutated proteins compared with wild type in cellular models. The mutated proteins activated the S6K1 and hyperphosphorylated the rpS6 and ERK1/2 signalling cascades, suggesting a gain-of-function effect.

CONCLUSIONS: Our study demonstrates for the first time that the variants in the gene are associated with HCM, and early detection of the variant carriers can help to identify family members at risk and subsequent preventive measures. Further screening in patients with HCM with different ethnic populations will establish the specificity and frequency of gene variants.

}, issn = {1468-6244}, doi = {10.1136/jmedgenet-2021-107866}, author = {Jain, Pratul Kumar and Jayappa, Shashank and Sairam, Thiagarajan and Mittal, Anupam and Paul, Sayan and Rao, Vinay J and Chittora, Harshil and Kashyap, Deepak K and Palakodeti, Dasaradhi and Thangaraj, Kumarasamy and Shenthar, Jayaprakash and Koranchery, Rakesh and Rajendran, Ranjith and Alireza, Haghighi and Mohanan, Kurukkanparampil Sreedharan and Rathinavel, Andiappan and Dhandapany, Perundurai S} } @article {2200, title = {tRNA-derived fragments (tRFs): establishing their turf in post-transcriptional gene regulation.}, journal = {Cell Mol Life Sci}, year = {2021}, month = {2021 Jan 02}, abstract = {

Transfer RNA (tRNA)-derived fragments (tRFs) are an emerging class of conserved small non-coding RNAs that play important roles in post-transcriptional gene regulation. High-throughput sequencing of multiple biological samples have identified heterogeneous species of tRFs with distinct functionalities. These small RNAs have garnered a lot of scientific attention due to their ubiquitous expression and versatility in regulating various biological processes. In this review, we highlight our current understanding of tRF biogenesis and their regulatory functions. We summarize the diverse modes of biogenesis through which tRFs are generated and discuss the mechanism through which different tRF species regulate gene expression and the biological implications. Finally, we conceptualize research areas that require focus to strengthen our understanding of the biogenesis and function of tRFs.

}, issn = {1420-9071}, doi = {10.1007/s00018-020-03720-7}, author = {Krishna, Srikar and Raghavan, Srikala and DasGupta, Ramanuj and Palakodeti, Dasaradhi} } @article {2109, title = {Modulation of β-catenin levels regulates cranial neural crest patterning and dispersal into first pharyngeal arch.}, journal = {Dev Dyn}, year = {2020}, month = {2020 May 19}, abstract = {

BACKGROUND: Vertebrate cranial neural crest cells (CNCCs) are multipotent, proximal to the source CNCC form the cranial ganglia. Distally, in the pharyngeal arches, they give rise to the craniofacial skeleton and connective tissues. Fate choices are made as CNCC pattern into distinct destination compartments. In spite of this importance, the mechanism patterning CNCC is poorly defined.

RESULTS: Here, we report that a novel β-catenin-dependent regulation of N-Cadherin levels may drive CNCC patterning. In mouse embryos, at the first pharyngeal arch axial level, membrane β-catenin levels correlate with the extent of N-cadherin-mediated adhesion and thus suggest the presence of collective and dispersed states of CNCC. Using in vitro human neural crest model and chemical modulators of β-catenin levels, we show a requirement for down-modulating β-catenin for regulating N-cadherin levels and cell-cell adhesion. Similarly, in β-catenin gain-of-function mutant mouse embryos, CNCC fail to lower N-cadherin levels. This indicates a failure to reduce cell-cell adhesion, which may underlie the failure of mutant CNCC to populate first pharyngeal arch.

CONCLUSION: We suggest that β-catenin-mediated regulation of CNCC adhesion, a previously underappreciated mechanism, underlies the patterning of CNCC into fate-specific compartments.

}, issn = {1097-0177}, doi = {10.1002/dvdy.208}, author = {Javali, Alok and Lakshmanan, Vairavan and Palakodeti, Dasaradhi and Sambasivan, Ramkumar} } @article {1740, title = {Dynamic expression of tRNA-derived small RNAs define cellular states.}, journal = {EMBO Rep}, volume = {20}, year = {2019}, month = {2019 Jul}, pages = {e47789}, abstract = {

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) have recently emerged as important regulators of protein translation and shown to have diverse biological functions. However, the underlying cellular and molecular mechanisms of tsRNA function in the context of dynamic cell-state transitions remain unclear. Expression analysis of tsRNAs in distinct heterologous cell and tissue models of stem vs. differentiated states revealed a differentiation-dependent enrichment of 5{\textquoteright}-tsRNAs. We report the identification of a set of 5{\textquoteright}-tsRNAs that is upregulated in differentiating mouse embryonic stem cells (mESCs). Notably, interactome studies with differentially enriched 5{\textquoteright}-tsRNAs revealed a switch in their association with "effector" RNPs and "target" mRNAs in different cell states. We demonstrate that specific 5{\textquoteright}-tsRNAs can preferentially interact with the RNA-binding protein, Igf2bp1, in the RA-induced differentiated state. This association influences the transcript stability and thereby translation of the pluripotency-promoting factor, c-Myc, thus providing a mechanistic basis for how 5{\textquoteright}-tsRNAs can modulate stem cell states in mESCs. Together our study highlights the role of 5{\textquoteright}-tsRNAs in defining distinct cell states.

}, issn = {1469-3178}, doi = {10.15252/embr.201947789}, author = {Krishna, Srikar and Yim, Daniel Gr and Lakshmanan, Vairavan and Tirumalai, Varsha and Koh, Judice Ly and Park, Jung Eun and Cheong, Jit Kong and Low, Joo Leng and Lim, Michelle Js and Sze, Siu Kwan and Shivaprasad, Padubidri and Gulyani, Akash and Raghavan, Srikala and Palakodeti, Dasaradhi and DasGupta, Ramanuj} } @article {1576, title = {KMT1 family methyltransferases regulate heterochromatin-nuclear periphery tethering via histone and non-histone protein methylation.}, journal = {EMBO Rep}, year = {2019}, month = {2019 Mar 11}, abstract = {

Euchromatic histone methyltransferases (EHMTs), members of the KMT1 family, methylate histone and non-histone proteins. Here, we uncover a novel role for EHMTs in regulating heterochromatin anchorage to the nuclear periphery (NP) via non-histone methylation. We show that EHMTs methylate and stabilize LaminB1 (LMNB1), which associates with the H3K9me2-marked peripheral heterochromatin. Loss of LMNB1 methylation or EHMTs abrogates heterochromatin anchorage at the NP We further demonstrate that the loss of EHMTs induces many hallmarks of aging including global reduction of H3K27methyl marks and altered nuclear morphology. Consistent with this, we observe a gradual depletion of EHMTs, which correlates with loss of methylated LMNB1 and peripheral heterochromatin in aging human fibroblasts. Restoration of EHMT expression reverts peripheral heterochromatin defects in aged cells. Collectively, our work elucidates a new mechanism by which EHMTs regulate heterochromatin domain organization and reveals their impact on fundamental changes associated with the intrinsic aging process.

}, issn = {1469-3178}, doi = {10.15252/embr.201643260}, author = {Rao, Radhika Arasala and Ketkar, Alhad Ashok and Kedia, Neelam and Krishnamoorthy, Vignesh K and Lakshmanan, Vairavan and Kumar, Pankaj and Mohanty, Abhishek and Kumar, Shilpa Dilip and Raja, Sufi O and Gulyani, Akash and Chaturvedi, Chandra Prakash and Brand, Marjorie and Palakodeti, Dasaradhi and Rampalli, Shravanti} } @article {1614, title = {Post-transcriptional regulation in planarian stem cells.}, journal = {Semin Cell Dev Biol}, volume = {87}, year = {2019}, month = {2019 Mar}, pages = {69-78}, abstract = {

Planarians are known for their immense regenerative abilities. A pluripotent stem cell population provides the cellular source for this process, as well as for the homeostatic cell turnover of the animals. These stem cells, known as neoblasts, present striking similarities at the morphological and molecular level to germ cells, but however, give rise to somatic tissue. Many RNA binding proteins known to be important for germ cell biology are also required for neoblast function, highlighting the importance of post-transcriptional regulation for stem cell control. Many of its aspects, including alternative splicing, alternative polyadenylation, translational control and mRNA deadenylation, as well as small RNAs such as microRNAs and piRNA are critical for stem cells. Their inhibition often abrogates both regeneration and cell turnover, resulting in lethality. Some of aspects of post-transcriptional regulation are conserved from planarian to mammalian stem cells.

}, issn = {1096-3634}, doi = {10.1016/j.semcdb.2018.05.013}, author = {Krishna, Srikar and Palakodeti, Dasaradhi and Solana, Jordi} } @article {1844, title = {Serotonin is essential for eye regeneration in planaria Schmidtea mediterranea.}, journal = {FEBS Lett}, year = {2019}, month = {2019 Sep 17}, abstract = {

Planaria is an ideal system to study factors involved in regeneration and tissue homeostasis. Little is known about the role of metabolites and small molecules in stem cell maintenance and lineage specification in planarians. Using liquid chromatography and mass spectrometry (LC-MS)-based quantitative metabolomics, we determined the relative levels of metabolites in stem cells, progenitors, and differentiated cells of the planarian Schmidtea mediterranea. Tryptophan and its metabolic product serotonin are significantly enriched in stem cells and progenitor population. Serotonin biosynthesis in these cells is brought about by a non-canonical enzyme, phenylalanine hydroxylase (PAH). Knockdown of Smed-pah leads to complete disappearance of eyes in regenerating planaria, while exogenous supply of serotonin and its precursor rescue the eyeless phenotype. Our results demonstrate a key role for serotonin in eye regeneration.

}, issn = {1873-3468}, doi = {10.1002/1873-3468.13607}, author = {Sarkar, Arunabha and Mukundan, Namita and Sowndarya, Sai and Dubey, Vinay Kumar and Babu, Rosana and Lakshmanan, Vairavan and Rangiah, Kannan and Panicker, Mitradas M and Palakodeti, Dasaradhi and Subramanian, Sabarinath Peruvemba and Ramaswamy, Subramanian} } @article {1981, title = {Stromal cells downregulate miR-23a-5p to activate protective autophagy in acute myeloid leukemia.}, journal = {Cell Death Dis}, volume = {10}, year = {2019}, month = {2019 Sep 30}, pages = {736}, abstract = {

Complex molecular cross talk between stromal cells and the leukemic cells in bone marrow is known to contribute significantly towards drug-resistance. Here, we have identified the molecular events that lead to stromal cells mediated therapy-resistance in acute myeloid leukemia (AML). Our work demonstrates that stromal cells downregulate miR-23a-5p levels in leukemic cells to protect them from the chemotherapy induced apoptosis. Downregulation of miR-23a-5p in leukemic cells leads to upregulation of protective autophagy by targeting TLR2 expression. Further, autophagy inhibitors when used as adjuvants along with conventional drugs can improve drug sensitivity in vitro as well in vivo in a mouse model of leukemia. Our work also demonstrates that this mechanism of bone marrow stromal cell mediated regulation of miR-23a-5p levels and subsequent molecular events are relevant predominantly in myeloid leukemia. Our results illustrate the critical and dynamic role of the bone marrow microenvironment in modulating miRNA expression in leukemic cells which could contribute significantly to drug resistance and subsequent relapse, possibly through persistence of minimal residual disease in this environment.

}, issn = {2041-4889}, doi = {10.1038/s41419-019-1964-8}, author = {Ganesan, Saravanan and Palani, Hamenth Kumar and Lakshmanan, Vairavan and Balasundaram, Nithya and Alex, Ansu Abu and David, Sachin and Venkatraman, Arvind and Korula, Anu and George, Biju and Balasubramanian, Poonkuzhali and Palakodeti, Dasaradhi and Vyas, Neha and Mathews, Vikram} } @article {1598, title = {FMRP Interacts with C/D Box snoRNA in the Nucleus and Regulates Ribosomal RNA Methylation.}, journal = {iScience}, volume = {9}, year = {2018}, month = {2018 Nov 30}, pages = {399-411}, abstract = {

FMRP is an RNA-binding protein that is known to localize in the cytoplasm and in the nucleus. Here, we have identified an interaction of FMRP with a specific set of C/D box snoRNAs in the nucleus. C/D box snoRNAs guide 2{\textquoteright}O methylations of ribosomal RNA (rRNA) on defined sites, and this modification regulates rRNA folding and assembly of ribosomes. 2{\textquoteright}O methylation of rRNA is partial on several sites in human embryonic stem cells, which results in ribosomes with differential methylation patterns. FMRP-snoRNA interaction affects rRNA methylation on several of these sites, and in the absence of FMRP, differential methylation pattern of rRNA is significantly altered. We found that FMRP recognizes ribosomes carrying specific methylation patterns on rRNA and the recognition of methylation pattern by FMRP may potentially determine the translation status of its target mRNAs. Thus, FMRP integrates its function in the nucleus and in the cytoplasm.

}, issn = {2589-0042}, doi = {10.1016/j.isci.2018.11.007}, author = {D{\textquoteright}Souza, Michelle Ninochka and Gowda, Naveen Kumar Chandappa and Tiwari, Vishal and Babu, Rosana Ottakandathil and Anand, Praveen and Dastidar, Sudhriti Ghosh and Singh, Randhir and James, Owen G and Selvaraj, Bhuvaneish and Pal, Rakhi and Ramesh, Arati and Chattarji, Sumantra and Chandran, Siddharthan and Gulyani, Akash and Palakodeti, Dasaradhi and Muddashetty, Ravi S} } @article {1153, title = {Identification of multiple isomeric core chitobiose-modified high-mannose and paucimannose -glycans in the planarian .}, journal = {J Biol Chem}, volume = {293}, year = {2018}, month = {2018 May 04}, pages = {6707-6720}, abstract = {

Cell surface-associated glycans mediate many cellular processes, including adhesion, migration, signaling, and extracellular matrix organization. The galactosylation of core fucose (GalFuc epitope) in paucimannose and complex-type -glycans is characteristic of protostome organisms, including flatworms (planarians). Although uninvestigated, the structures of these glycans may play a role in planarian regeneration. Whole-organism MALDI-MS analysis of -linked oligosaccharides from the planarian revealed the presence of multiple isomeric high-mannose and paucimannose structures with unusual mono-, di-, and polygalactosylated ( = 3-5) core fucose structures; the latter structures have not been reported in other systems. Di- and trigalactosylated core fucoses were the most dominant glycomers. -Glycans showed extensive, yet selective, methylation patterns, ranging from non-methylated to polymethylated glycoforms. Although the majority of glycoforms were polymethylated, a small fraction also consisted of non-methylated glycans. Remarkably, monogalactosylated core fucose remained unmethylated, whereas its polygalactosylated forms were methylated, indicating structurally selective methylation. Using database searches, we identified two potential homologs of the Galβ1-4Fuc-synthesizing enzyme from nematodes (GALT-1) that were expressed in the prepharyngeal, pharyngeal, and mesenchymal regions in The presence of two GALT-1 homologs suggests different requirements for mono- and polygalactosylation of core fucose for the formation of multiple isomers. Furthermore, we observed variations in core fucose glycosylation patterns in different planarian strains, suggesting evolutionary adaptation in fucose glycosylation. The various core chitobiose modifications and methylations create \>60 different glycoforms in These results contribute greatly to our understanding of -glycan biosynthesis and suggest the presence of a GlcNAc-independent biosynthetic pathway in

}, issn = {1083-351X}, doi = {10.1074/jbc.RA117.000782}, author = {Subramanian, Sabarinath Peruvemba and Babu, Ponnusamy and Palakodeti, Dasaradhi and Subramanian, Ramaswamy} } @article {1577, title = {Quantification of Neurotransmitters from Intact and Regenerating Planarians Using UHPLC-MS/SRM Method.}, journal = {Methods Mol Biol}, volume = {1774}, year = {2018}, month = {2018}, pages = {555-570}, abstract = {

Freshwater planarian species S. mediterranea is an emerging stem cell model because of its capability of regenerating large portions of missing body parts. It is one of the best model systems available to address the basic biological mechanisms in the regeneration processes. Absolute quantification of metabolites from planarians is imperative to understand their role in the regeneration processes. Here we describe a stable isotope dilution ultrahigh performance liquid chromatography/mass spectrometry/selected reaction monitoring (UHPLC-MS/SRM) assay for a sensitive and quantitative assessment of neurotransmitters (NTs) in planaria. We used this method for the simultaneous quantification of 16 NTs from both intact and regenerating planarians.

}, keywords = {Animals, Chromatography, High Pressure Liquid, Neurotransmitter Agents, Planarians, Regeneration, Stem Cells, Tandem Mass Spectrometry}, issn = {1940-6029}, doi = {10.1007/978-1-4939-7802-1_25}, author = {Rangiah, Kannan and Palakodeti, Dasaradhi} } @article {1160, title = {Cytoplasmic poly (A)-binding protein critically regulates epidermal maintenance and turnover in the planarian .}, journal = {Development}, volume = {144}, year = {2017}, month = {2017 09 01}, pages = {3066-3079}, abstract = {

Identifying key cellular events that facilitate stem cell function and tissue organization is crucial for understanding the process of regeneration. Planarians are powerful model system to study regeneration and stem cell (neoblast) function. Here, using planaria, we show that the initial events of regeneration, such as epithelialization and epidermal organization are critically regulated by a novel cytoplasmic poly A-binding protein, SMED-PABPC2. Knockdown leads to defects in epidermal lineage specification, disorganization of epidermis and ECM, and deregulated wound healing, resulting in the selective failure of neoblast proliferation near the wound region. Polysome profiling suggests that epidermal lineage transcripts, including , are translationally regulated by SMED-PABPC2 Together, our results uncover a novel role for SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing and subsequent processes for regeneration.

}, keywords = {Animals, Cell Lineage, Cell Proliferation, Cytoplasm, Epidermis, Epithelium, Extracellular Matrix, Gene Knockdown Techniques, Homeostasis, Models, Biological, Planarians, Poly(A)-Binding Protein I, Regeneration, RNA, Messenger, Wound Healing}, issn = {1477-9129}, doi = {10.1242/dev.152942}, author = {Bansal, Dhiru and Kulkarni, Jahnavi and Nadahalli, Kavana and Lakshmanan, Vairavan and Krishna, Srikar and Sasidharan, Vidyanand and Geo, Jini and Dilipkumar, Shilpa and Pasricha, Renu and Gulyani, Akash and Raghavan, Srikala and Palakodeti, Dasaradhi} } @article {1163, title = {Hierarchies in light sensing and dynamic interactions between ocular and extraocular sensory networks in a flatworm.}, journal = {Sci Adv}, volume = {3}, year = {2017}, month = {2017 Jul}, pages = {e1603025}, abstract = {

Light sensing has independently evolved multiple times under diverse selective pressures but has been examined only in a handful among the millions of light-responsive organisms. Unsurprisingly, mechanistic insights into how differential light processing can cause distinct behavioral outputs are limited. We show how an organism can achieve complex light processing with a simple "eye" while also having independent but mutually interacting light sensing networks. Although planarian flatworms lack wavelength-specific eye photoreceptors, a 25 nm change in light wavelength is sufficient to completely switch their phototactic behavior. Quantitative photoassays, eye-brain confocal imaging, and RNA interference/knockdown studies reveal that flatworms are able to compare small differences in the amounts of light absorbed at the eyes through a single eye opsin and convert them into binary behavioral outputs. Because planarians can fully regenerate, eye-brain injury-regeneration studies showed that this acute light intensity sensing and processing are layered on simple light detection. Unlike intact worms, partially regenerated animals with eyes can sense light but cannot sense finer gradients. Planarians also show a "reflex-like," eye-independent (extraocular/whole-body) response to low ultraviolet A light, apart from the "processive" eye-brain-mediated (ocular) response. Competition experiments between ocular and extraocular sensory systems reveal dynamic interchanging hierarchies. In intact worms, cerebral ocular response can override the reflex-like extraocular response. However, injury-regeneration again offers a time window wherein both responses coexist, but the dominance of the ocular response is reversed. Overall, we demonstrate acute light intensity-based behavioral switching and two evolutionarily distinct but interacting light sensing networks in a regenerating organism.

}, issn = {2375-2548}, doi = {10.1126/sciadv.1603025}, author = {Shettigar, Nishan and Joshi, Asawari and Dalmeida, Rimple and Gopalkrishna, Rohini and Chakravarthy, Anirudh and Patnaik, Siddharth and Mathew, Manoj and Palakodeti, Dasaradhi and Gulyani, Akash} } @article {1199, title = {The miR-124 family of microRNAs is crucial for regeneration of the brain and visual system in the planarian Schmidtea mediterranea}, journal = {Development}, volume = {144}, year = {2017}, pages = {3211{\textendash}3223}, abstract = {

Brain regeneration in planarians is mediated by precise spatiotemporal control of gene expression and is crucial for multiple aspects of neurogenesis. However, the mechanisms underpinning the gene regulation essential for brain regeneration are largely unknown. Here, we investigated the role of the miR-124 family of microRNAs in planarian brain regeneration. The miR-124 family (miR-124) is highly conserved in animals and regulates neurogenesis by facilitating neural differentiation, yet its role in neural wiring and brain organization is not known. We developed a novel method for delivering anti-miRs using liposomes for the functional knockdown of microRNAs. Smed-miR-124 knockdown revealed a key role for these microRNAs in neuronal organization during planarian brain regeneration. Our results also demonstrated an essential role for miR-124 in the generation of eye progenitors. Additionally, miR-124 regulates Smed-slit-1, which encodes an axon guidance protein, either by targeting slit-1 mRNA or, potentially, by modulating the canonical Notch pathway. Together, our results reveal a role for miR-124 in regulating the regeneration of a functional brain and visual system.

}, issn = {0950-1991}, doi = {10.1242/dev.144758}, url = {http://dev.biologists.org/content/144/18/3211}, author = {Sasidharan, Vidyanand and Marepally, Srujan and Elliott, Sarah A. and Baid, Srishti and Lakshmanan, Vairavan and Nayyar, Nishtha and Bansal, Dhiru and S{\'a}nchez Alvarado, Alejandro and Vemula, Praveen Kumar and Palakodeti, Dasaradhi} } @article {1170, title = {Genome-Wide Analysis of Polyadenylation Events in Schmidtea mediterranea.}, journal = {G3 (Bethesda)}, volume = {6}, year = {2016}, month = {2016 10 13}, pages = {3035-3048}, abstract = {

In eukaryotes, 3{\textquoteright} untranslated regions (UTRs) play important roles in regulating posttranscriptional gene expression. The 3{\textquoteright}UTR is defined by regulated cleavage/polyadenylation of the pre-mRNA. The advent of next-generation sequencing technology has now enabled us to identify these events on a genome-wide scale. In this study, we used poly(A)-position profiling by sequencing (3P-Seq) to capture all poly(A) sites across the genome of the freshwater planarian, Schmidtea mediterranea, an ideal model system for exploring the process of regeneration and stem cell function. We identified the 3{\textquoteright}UTRs for \~{}14,000 transcripts and thus improved the existing gene annotations. We found 97 transcripts, which are polyadenylated within an internal exon, resulting in the shrinking of the ORF and loss of a predicted protein domain. Around 40\% of the transcripts in planaria were alternatively polyadenylated (ApA), resulting either in an altered 3{\textquoteright}UTR or a change in coding sequence. We identified specific ApA transcript isoforms that were subjected to miRNA mediated gene regulation using degradome sequencing. In this study, we also confirmed a tissue-specific expression pattern for alternate polyadenylated transcripts. The insights from this study highlight the potential role of ApA in regulating the gene expression essential for planarian regeneration.

}, keywords = {3{\textquoteright} Untranslated Regions, Animals, Computational Biology, Genome, Helminth, Genome-Wide Association Study, High-Throughput Nucleotide Sequencing, MicroRNAs, Molecular Sequence Annotation, Platyhelminths, Poly A, Polyadenylation, Reproducibility of Results, RNA Interference, RNA Processing, Post-Transcriptional, RNA, Messenger}, issn = {2160-1836}, doi = {10.1534/g3.116.031120}, author = {Lakshmanan, Vairavan and Bansal, Dhiru and Kulkarni, Jahnavi and Poduval, Deepak and Krishna, Srikar and Sasidharan, Vidyanand and Anand, Praveen and Seshasayee, Aswin and Palakodeti, Dasaradhi} } @article {2271, title = {A quantitative metabolomics peek into planarian regeneration.}, journal = {Analyst}, volume = {140}, year = {2015}, month = {2015 May 21}, pages = {3445-64}, abstract = {

The fresh water planarian species Schmidtea mediterranea is an emerging stem cell model because of its capability to regenerate a whole animal from a small piece of tissue. It is one of the best model systems to address the basic mechanisms essential for regeneration. Here, we are interested in studying the roles of various amines, thiols and nucleotides in planarian regeneration, stem cell function and growth. We developed mass spectrometry based quantitative methods and validated the differential enrichment of 35 amines, 7 thiol metabolites and 4 nucleotides from both intact and regenerating planarians. Among the amines, alanine in sexual and asparagine in asexual are the highest (\>1000 ng/mg) in the intact planarians. The levels of thiols such as cysteine and GSH are 651 and 1107 ng mg(-1) in planarians. Among the nucleotides, the level of cGMP is the lowest (0.03 ng mg(-1)) and the level of AMP is the highest (187 ng mg(-1)) in both of the planarian strains. We also noticed increasing levels of amines in both anterior and posterior regenerating planarians. The blastema from day 3 regenerating planarians also showed higher amounts of many amines. Interestingly, the thiol (cysteine and GSH) levels are well maintained during planarian regeneration. This suggests an inherent and effective mechanism to control induced oxidative stress because of the robust regeneration and stem cell proliferation. Like in intact planarians, the level of cGMP is also very low in regenerating planarians. Surprisingly, the levels of amines and thiols in head regenerating blastemas are \~{}3 times higher compared to those for tail regenerating blastemas. Thus our results strongly indicate the potential roles of amines, thiols and nucleotides in planarian regeneration.

}, keywords = {Animals, Calibration, Chromatography, High Pressure Liquid, Limit of Detection, Metabolomics, Planarians, Reference Standards, Regeneration, Reproduction, Asexual, Species Specificity, Tandem Mass Spectrometry}, issn = {1364-5528}, doi = {10.1039/c4an02037e}, author = {Natarajan, Nivedita and Ramakrishnan, Padma and Lakshmanan, Vairavan and Palakodeti, Dasaradhi and Rangiah, Kannan} }