Biology subjects

Vemuri, K.

Publications and source records attributed to Vemuri, K..

4 recordsLinked to original sources

bioRxiv2024

Diet-induced obesity mediated through Estrogen-Related Receptor α is independent of intestinal function

Obesity has become an epidemic, prompting advances in therapies targeting this condition. Estrogen-related receptor (ESRRA), a transcription factor, plays pivotal roles in energy metabolism across diverse tissues. Studies have demonstrated that loss of Esrra leads to fat malabsorption and resistance to diet-induced obesity. However, the reliance of these studies on germline Esrra mutants overlooks the tissue-specific implications of ESRRA in diet-induced obesity. Notably, Esrra exhibits high expression in the gastrointestinal (GI) tract relative to other tissues. Given the critical role of the GI tract in dietary lipid metabolism, this study employs mouse genetics and genomics approaches to dissect the specific impact of intestinal ESRRA along with investigating its role in diet-induced obesity. Data TransparencyChIP-seq and RNA-seq data from this publication have been deposited to GEO accession numbers GSE269824 and GSE269825, respectively. Any additional information required to reanalyze the data reported in this paper is available from the corresponding author upon request. Grant SupportThis research was funded by grants from the National Institutes of Health (NIH) to M.P.V. (R01DK121915 and R01DK126446). K.V. was supported by an American Heart Association pre-doctoral fellowship (906006). S.K. was supported by a Rutgers DLS Summer Undergraduate Research Fellowship. A.L. was supported by grants from the NIH grant F31DK137596 and the NIH T32 Biotechnology Training Program (GM135141). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. DisclosuresThe authors declare no competing interests.

genetics↗

bioRxiv2023

Dynamic RNA Polymerase II Recruitment Drives Differentiation of the Intestine under the direction of HNF4

Terminal differentiation requires a massive restructuring of the transcriptome. During intestinal differentiation, the expression patterns of nearly 4000 genes are altered as cells transition from progenitor cells in crypts to differentiated cells in villi. We identified dynamic recruitment of RNA Polymerase II (Pol II) to gene promoters as the primary driver of transcriptomic shifts during intestinal differentiation in vivo. Changes in enhancer-promoter looping interactions accompany dynamic Pol II recruitment and are dependent upon HNF4, a pro-differentiation transcription factor. Using genetic loss-of-function, ChIP-seq and IP mass spectrometry, we demonstrate that HNF4 collaborates with chromatin remodelers and loop-stabilizing proteins and facilitates Pol II recruitment at hundreds of genes pivotal to differentiation. We also explore alternate mechanisms which drive differentiation gene expression and find pause-release of Pol II and post-transcriptional mRNA stability regulate smaller subsets of differentially expressed genes. These studies provide insights into the mechanisms of differentiation in a renewing adult tissue. HIGHLIGHTSO_LIDynamic recruitment of Pol II largely drives the vast transcriptomic changes seen during differentiation of mouse intestinal epithelium. C_LIO_LISmaller groups of differentiated genes are subject to regulation through Pol II pause-release and post-transcriptional mechanisms such as differences in mRNA stability. C_LIO_LIIP-mass spectrometry analysis identifies the first interactome of HNF4 in the differentiated small intestine, finding interactions with chromatin looping and chromatin remodeling proteins. C_LIO_LIHNF4 transcription factors play a critical role in recruiting Pol II to the promoters of essential intestinal differentiation genes. C_LI

genetics↗

bioRxiv2022

Modulation of cannabinoid receptor signaling by endocannabinoids

Endocannabinoids (eCBs) are endogenous lipid molecules that activate the cannabinoid receptor 1 (CB1), a G protein coupled receptor (GPCR) that signals primarily through the Gi/o family of G proteins to regulate neurotransmitter release. Consequently, CB1 is an important therapeutic target for several neurological disorders. How eCBs interact with CB1 is not known and the downstream signaling they activate is not well understood. In this study we show that eCBs do not activate Gi1 as much as synthetic cannabinoids. To characterize activation of CB1 by eCB, we formed an eCB analogue-bound (AMG315) CB1-Gi signaling complex for structural studies. The structure reveals differences in the orthosteric ligand binding pocket not seen in the previous CB1 structures, providing insights into the structural determinants of ligand efficacy. In combination with signaling and simulation data, this study provides mechanistic insights into CB1 activation by different classes of ligands, and sheds light on the G protein preferences between endogenous and exogenous ligands.

biochemistry↗

bioRxiv2018

In vitro determination of the CB1 efficacy of illicit synthetic cannabinoids

BACKGROUND AND PURPOSEThe morbidity and mortality associated with recreational use of synthetic cannabinoid receptor agonists (SCRAs) is a major health concern, and may involve over-activation of CB1 receptors. Thus, we sought to determine the efficacy of 13 SCRAs at CB1 using receptor depletion with the irreversible CB1 antagonist AM6544 followed by fitting the curve with the Black and Leff operational model to calculate efficacy.\n\nEXPERIMENTAL APPROACHReceptor depletion in mouse AtT-20 neuroblastoma cells stably expressing human CB1 was achieved by pre-treatment of cells with AM6544 (10 {micro}M, 60 mins). The CB1-mediated hyperpolarisation of AtT20 cells was measured using membrane potential dye. From data fit to the operational model, the efficacy (tau) and affinity (KA) parameters were obtained for each drug.\n\nKEY RESULTSAM6544 did not affect the potency or maximal effect of native somatostatin receptor-induced hyperpolarisation (Control, pEC50 9.13 {+/-} 0.05, Emax 38 {+/-} 1%; AM6544 treated pEC50 9.18 {+/-} 0.04, Emax 39 {+/-} 0.7%). The tau value of {triangleup}9-THC was 70-fold less than the reference CB-agonist CP55940, and 240-fold less than the highest efficacy SCRA, 5F-MDMB-PICA. Most of the SCRAs had about 50% of the efficacy of CP55940. There was no correlation between the tau and KA values for any SCRA.\n\nCONCLUSION AND IMPLICATIONSAll the SCRA tested showed substantially higher agonist activity at CB1 than {triangleup}9-THC, which may contribute to the adverse effects seen with these drugs but not {triangleup}9-THC, although the mechanisms underlying SCRA toxicity are still poorly defined.

pharmacology and toxicology↗