Biology subjects

Sethupathy, P.

Publications and source records attributed to Sethupathy, P..

4 recordsLinked to original sources

bioRxiv2018

EndoC-βH1 multi-genomic profiling defines gene regulatory programs governing human pancreatic β cell identity and function

EndoC-{beta}H1 is emerging as a critical human beta cell model to study the genetic and environmental etiologies of beta cell function, especially in the context of diabetes. Comprehensive knowledge of its molecular landscape is lacking yet required to fully take advantage of this model. Here, we report extensive chromosomal (spectral karyotyping), genetic (genotyping), epigenetic (ChIP-seq, ATAC-seq), chromatin interaction (Hi-C, Pol2 ChIA-PET), and transcriptomic (RNA-seq, miRNA-seq) maps of this cell model. Integrated analyses of these maps define known (e.g., PDX1, ISL1) and putative (e.g., PCSK1, mir-375) beta cell-specific chromatin interactions and transcriptional cis-regulatory networks, and identify allelic effects on cis-regulatory element use and expression.\n\nImportantly, comparative analyses with maps generated in primary human islets/beta cells indicate substantial preservation of chromatin looping, but also highlight chromosomal heterogeneity and fetal genomic signatures in EndoC-{beta}H1. Together, these maps, and an interactive web application we have created for their exploration, provide important tools for the broad community in the design and success of experiments to probe and manipulate the genetic programs governing beta cell identity and (dys)function in diabetes.

genomics↗

bioRxiv2018

Association Between Colonic Level of microRNA 31 and Subtypes of Adult and Pediatric Crohn’s Disease

Crohns disease (CD) is highly heterogeneous, due in large part to variability in cellular processes that underlie the natural history of CD, thereby confounding effective therapy. There is a critical need to advance understanding of the cellular mechanisms that drive CD heterogeneity. In this study, small RNA-sequencing and microRNA profiling in the colon revealed two distinct molecular subtypes, each with different clinical associations, in both adult and treatment-naive pediatric CD patients. Notably, we found that microRNA-31 (miR-31) expression by itself can stratify patients into these two subtypes. Through detailed analysis of several colonic mucosa cell types from adult patients, we found that differential levels of miR-31 are particularly pronounced in epithelial cells. We generated patient crypt-derived epithelial colonoids and showed that miR-31 expression differences preserved in this ex-vivo system. In adult patients, low colonic miR-31 expression levels at the time of surgery are associated with post-operative recurrence of ileal disease. In pediatric patients, lower miR-31 expression at the time of diagnosis is associated with the future development of fibrostenotic ileal CD requiring surgery. These findings represent an important step forward in designing more effective clinical trials and developing personalized therapies for CD.

genomics↗

bioRxiv2018

Bioinformatic analysis of endogenous and exogenous small RNAs on lipoproteins

To comprehensively study extracellular small RNAs (sRNA) by sequencing (sRNA-seq), we developed a novel pipeline to overcome current limitations in analysis entitled, \"Tools for Integrative Genome analysis of Extracellular sRNAs (TIGER)\". To demonstrate the power of this tool, sRNA-seq was performed on mouse lipoproteins, bile, urine, and liver samples. A key advance for the TIGER pipeline is the ability to analyze both host and non-host sRNAs at genomic, parent RNA, and individual fragment levels. TIGER was able to identify approximately 60% of sRNAs on lipoproteins, and >85% of sRNAs in liver, bile, and urine, a significant advance compared to existing software. Results suggest that the majority of sRNAs on lipoproteins are non-host sRNAs derived from bacterial sources in the microbiome and environment, specifically rRNA-derived sRNAs from Proteobacteria. Collectively, TIGER facilitated novel discoveries of lipoprotein and biofluid sRNAs and has tremendous applicability for the field of extracellular RNA.

bioinformatics↗

bioRxiv2016

Functional transcriptomics in diverse intestinal epithelial cell types reveals robust gut microbial sensitivity of microRNAs in intestinal stem cells

Gut microbiota play an important role in regulating the development of the host immune system, metabolic rate, and at times, disease pathogenesis. The factors and mechanisms that mediate communication between microbiota and the intestinal epithelium are poorly understood. We provide novel evidence that microbiota may control intestinal epithelial stem cell (IESC) proliferation in part through microRNAs (miRNAs). We demonstrate that miRNA profiles differ dramatically across functionally distinct cell types of the mouse jejunal intestinal epithelium and that miRNAs respond to microbiota in a highly cell-type specific manner. Importantly, we also show that miRNAs in IESCs are more prominently regulated by microbiota compared to miRNAs in any other intestinal epithelial cell (IEC) subtype. We identify miR-375 as one miRNA that is significantly suppressed by the presence of microbiota in IESCs. Using a novel method to knockdown gene and miRNA expression ex vivo enteroids, we demonstrate that we can knockdown gene expression in Lgr5+ IESCs. Furthermore, when we knockdown miR-375 in IESCs, we observe significantly increased proliferative capacity. Understanding the mechanisms by which microbiota regulate miRNA expression in IESCs and other IEC subtypes will elucidate a critical molecular network that controls intestinal homeostasis and, given the heightened interest in miRNA-based therapies, may offer novel therapeutic strategies in the treatment of gastrointestinal diseases associated with altered IESC function.

genomics↗