Project description:The high prevalence of obesity has focused attention on defining the pathophysiological processes that underlie susceptibility or resistance to its deleterious metabolic consequences. Mice lacking translin (Tsn), a gene implicated in a variety of biological functions from transcription to microRNA degradation, display extremely high levels of adiposity, comparable to those found in well-known genetic models of obesity, such as melanocortin 4 receptor or leptin knockout (KO) mice. Although translin KO mice display increased adiposity they retain normal glucose tolerance. In contrast, wild-type (WT) mice placed on a high-fat diet until they match translin KO adiposity levels are glucose intolerant, as expected. Conversely, translin KO mice display prominent hepatic steatosis that is more severe than that of adiposity-matched WT mice. The ability of translin KO mice to retain normal glucose tolerance in the face of massive tissue expansion may be due to three factors: preferential accumulation of subcutaneous fat, reduced levels of TNF mRNA in both adipose and hepatic tissue, and elevated levels of plasma adiponectin. Further studies aimed at defining the molecular bases for these phenotypes may yield new approaches to limit the adverse metabolic consequences of obesity.
Project description:Obesity is linked to the development of metabolic disorders. Expansion of white adipose tissue (WAT) from hypertrophy of pre-existing adipocytes and/or differentiation of precursors into new mature adipocytes contributes to obesity. We found that Nck2 expression is largely restricted to WAT, raising the hypothesis that it may play a unique function in that tissue. Using mice lacking Nck2, we found that Nck2 regulates adipocyte hypertrophy thus contributing to increased adiposity and progressive glucose intolerance, insulin resistance and hepatic steatosis. These findings were recapitulated in humans such that Nck2 expression in omental WAT was inversely correlated with the degree of obesity. Mechanistically, Nck2 deficiency promoted the induction of an adipocyte differentiation program and signaling by the PERK-eIF2α-ATF4 pathway in agreement with a role for the unfolded protein response in adipogenesis. These findings uncover Nck2 as a novel regulator of adipogenesis and that perturbation in its functionality contributes to adiposity-related metabolic disorders. Differential gene expression profile between epididymal white adipose tissue of Nck2-/- and Nck2+/+ mice by RNA sequencing (Illumina HiSEq 2000)
Project description:Obesity is linked to the development of metabolic disorders. Expansion of white adipose tissue (WAT) from hypertrophy of pre-existing adipocytes and/or differentiation of precursors into new mature adipocytes contributes to obesity. We found that Nck2 expression is largely restricted to WAT, raising the hypothesis that it may play a unique function in that tissue. Using mice lacking Nck2, we found that Nck2 regulates adipocyte hypertrophy thus contributing to increased adiposity and progressive glucose intolerance, insulin resistance and hepatic steatosis. These findings were recapitulated in humans such that Nck2 expression in omental WAT was inversely correlated with the degree of obesity. Mechanistically, Nck2 deficiency promoted the induction of an adipocyte differentiation program and signaling by the PERK-eIF2α-ATF4 pathway in agreement with a role for the unfolded protein response in adipogenesis. These findings uncover Nck2 as a novel regulator of adipogenesis and that perturbation in its functionality contributes to adiposity-related metabolic disorders.
Project description:Homozygous K107R mutation of PPARg in mice alters the expression of its downstream target genes and increases insulin sensitivity but not adiposity.
Project description:Many genes have been implicated in WAT lipid metabolism, including tripartite motif containing 28 (Trim28), a gene proposed to primarily influence adiposity via epigenetic mechanisms in embryonic development. We set out to determine if adipose specific deletion of Trim28 led to changes in adipose tissue function and molecular phenotype. We performed transcriptomics analysis on adipose tissue taken from WT and adipose specific Trim28 KO mice to investigate their molecular phenotype, and to identify pathways altered in KO animals.
Project description:This first-in-human (FIH) dose-escalation and dose-validation/expansion study will assess KO-2806, a farnesyl transferase inhibitor (FTI), as a monotherapy and in combination, in adult patients with advanced solid tumors.
Project description:We previously identified Keratinocyte-associated protein 3, Krtcap3, as an obesity-related gene in female rats where a whole-body Krtcap3 knock-out (KO) led to increased adiposity compared to wild-type (WT) controls when fed a high-fat diet (HFD). We sought to replicate this work to better understand the function of Krtcap3 but were unable to reproduce the adiposity phenotype. In the current work, WT female rats ate more compared to WT in the prior study, with corresponding increases in body weight and fat mass, while there were no changes in these measures in KO females between the studies. The prior study was conducted before the COVID-19 pandemic, while the current study started after initial lock-down orders and was completed during the pandemic with a generally less stressful environment. We hypothesize that the environmental changes impacted stress levels and may explain the failure to replicate our results. Analysis of corticosterone (CORT) at euthanasia showed a significant study by genotype interaction where WT had significantly higher CORT relative to KO in Study 1, with no differences in Study 2. These data suggest that decreasing Krtcap3 expression may alter the environmental stress response to influence adiposity. We also found that KO rats in both studies, but not WT, experienced a dramatic increase in CORT after their cage mate was removed, suggesting a separate connection to social behavioral stress. Future work is necessary to confirm and elucidate the finer mechanisms of these relationships, but these data indicate the possibility of Krtcap3 as a novel stress gene.
Project description:C18ORF25 is a homolog of Arkadia (RNF111), an E3 ubiquitin ligase with SUMO-interaction motifs (SIMs) (PMID: 31417085). However, C18ORF25 lacks the entire C-terminal RING domain of RNF111 which is required for ubiquitin binding suggesting it lacks ubiquitination activity and may therefore act as an adaptor or signalling scaffold (PMID: 26283374). We have previously shown that mice lacking C18Orf25 throughout the entire body have increased adiposity, decreased lean mass, lower exercise capacity and significantly reduced ex vivo skeletal muscle force production (PMID: 35882232). Skeletal muscle isolated from C18Orf25 knockout (KO) mice have reduced cAMP-dependent protein kinase A (PKA) levels, and reduced phosphorylation of several contractile proteins and proteins involved in calcium handling. Furthermore, analysis of single muscle fibres from C18Orf25 KO mice revealed impaired SR calcium cycling in fast-twitch fibres only (PMID: 35882232). Hence, we investigated these mechanisms by developing an integrated single-fibre physiology and single-fibre proteomic platform. The platform enabled us to identify hundreds of novel phenotype:protein correlations. The analysis also enabled us to identify proteome differences specifically in FT fibres following loss of C18ORF25. Taken together, our data suggest C18ORF25 is likely a multi-functional protein with several underlying mechanisms contributing to skeletal muscle physiology.
Project description:The endogenous RNA substrates of Translin-TRAX complexes (also known as C3POs) and how they regulate diverse biological processes remain unknown. Here we show that Translin and TRAX do not play a significant role in RNAi in the filamentous fungus Neurospora crassa. Instead, the Neurospora C3PO complex functions as a ribonuclease that removes the 5M-bM-^@M-^Y pre-tRNA fragments after the processing of pre-tRNAs by RNase P. In translin and trax mutants, 5M-bM-^@M-^Y pre-tRNA fragments accumulate to very high levels that can be degraded specifically by both recombinant and endogenous Neurospora C3PO and recombinant Drosophila C3PO. In addition, the mutants have elevated tRNA levels and increased levels of protein translation and are more resistant to a programmed cell-death inducing agent. Together, this study identified the endogenous RNA substrates of C3PO and provides a potential explanation for its roles in seemingly diverse biological processes. Examine small RNA population changes in two different strain background