Project description:Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell–deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue–resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue–resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance. four samples
Project description:Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell–deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue–resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue–resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance.
Project description:The popularity of high fat foods in modern society has been associated with epidemic of various metabolic diseases characterized by insulin resistance, the pathology of which involves complex interactions between multiple tissues such as liver, skeletal muscle and white adipose tissue (WAT). To uncover the mechanism by which excessive fat impairs insulin sensitivity, we conducted a multi- tissue study by using TMT-based quantitative proteomics. 3-week-old ICR mice were fed with high fat diet (HFD) for 19 weeks to induce insulin resistance. Liver, skeletal muscle and epididymal fat were collected for proteomics screening. Additionally, PRM was used for validating adipose differential proteins. By comparing tissue-specific protein profiles of HFD mice, multi-tissue regulation of glucose and lipid homeostasis and corresponding underlying mechanisms was systematically investigated and characterized. NC: normal birth weight + chow diet; NH: normal birth weight + high fat diet; LC: low birth weight + chow diet; LH: low birth weight + high fat diet.
Project description:We studied the role of the cAMP responsive factor CREB in promoting insulin resistance following its activation in adipose under obese conditions; We identified genes that were upregulated in primary cultures of mouse adipocytes following exposure to forskolin; and we characterized genes that are also induced in white adipose tissue in mice maintained on a high fat diet. Experiment Overall Design: Primary cultures of mouse adipocytes,harvested from visceral adipose tissue, were exposed to forskolin (10uM) or vehicle control (DMSO) for 2 hours. White adipose tissue (epididymal fat pads) were collected from mice maintained on a 60% high fat diet for 12 weeks and from control mice on normal chow.
Project description:We previously demonstrated that antisense oligonucleotide (ASO)-mediated knockdown of Mboat7, the gene encoding Membrane Bound O-Acyltransferase 7, in the liver and adipose tissue of mice promoted high fat diet-induced hepatic steatosis, hyperinsulinemia, and systemic insulin resistance. Thereafter, other groups showed that hepatocyte-specific genetic deletion of Mboat7 promoted striking fatty liver and NAFLD progression in mice but does not alter insulin sensitivity, suggesting the potential for cell autonomous roles. Here, we show that MBOAT7 function in adipocytes contributes to diet-induced metabolic disturbances including hyperinsulinemia and systemic insulin resistance. We generated floxed Mboat7 mice and created hepatocyte- and adipocyte-specific knockout mice using Cre-recombinase mice under the control of the albumin and adiponectin promoter, respectively. After chow and high fat diet feeding (60% kCal fat), mice were subjected to metabolic phenotyping and tissues to molecular workup and analysis. Here, we show that MBOAT7 function in adipocytes contributes to diet-induced metabolic disturbances including hyperinsulinemia and systemic insulin resistance. The expression of Mboat7 in white adipose tissue closely correlates with diet-induced obesity across a panel of ~100 inbred strains of mice fed a high fat/high sucrose diet. Moreover, we found that adipocyte-specific genetic deletion of Mboat7 is sufficient to promote hyperinsulinemia, systemic insulin resistance, and mild fatty liver. Unlike in the liver, where Mboat7 plays a relatively minor role in maintaining arachidonic acid (AA)-containing PI pools, Mboat7 is the major source of AA-containing PI pools in adipose tissue. Our data demonstrate that MBOAT7 is a critical regulator of adipose tissue PI homeostasis, and adipocyte MBOAT7-driven PI biosynthesis is closely linked to hyperinsulinemia and insulin resistance in mice.
Project description:In the present study, we used C57BL/6J mouse, as a model for studying diet-induced diabetes and obesity, since this strain accumulates adipose tissue mass, insulin resistance, hyper-insulinemia, and hyper-lipidemia similar to humans fed on an high-fat high-sugar diet (HFHSD).
Project description:In the present study, we used C57BL/6J mouse, as a model for studying diet-induced diabetes and obesity, since this strain accumulates adipose tissue mass, insulin resistance, hyper-insulinemia, and hyper-lipidemia similar to humans fed on an high-fat high-sugar diet (HFHSD).
Project description:In the present study, we used C57BL/6J mouse, as a model for studying diet-induced diabetes and obesity, since this strain accumulates adipose tissue mass, insulin resistance, hyper-insulinemia, and hyper-lipidemia similar to humans fed on an high-fat high-sugar diet (HFHSD).