@article {88157, 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 {22019, title = {Cytoplasmic poly (A) binding protein (PABPC2) critically regulates epidermal maintenance and turnover in planarian Schmidtea mediterranea.}, journal = {Development}, year = {2017}, month = {2017 Aug 14}, abstract = {

Identifying key cellular events that facilitate stem cell function and tissue organization is critical 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 (KD) of Smed-pabpc2 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 suggested epidermal lineage transcripts, including zfp-1, to be translationally regulated by SMED-PABPC2. Together, our results uncover a novel role of SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing, and subsequent processes for regeneration.

}, 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 {11620, title = {Genome-Wide Analysis of Polyadenylation Events in Schmidtea mediterranea.}, journal = {G3 (Bethesda)}, volume = {6}, year = {2016}, month = {2016 Oct 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.

}, 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} }