Project description:Obesity leads to a state of chronic low-grade inflammation that features accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid droplet accumulation in the development of obesity-induced adipose tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency markedly reduced intracellular lipid levels and accumulation of fluorescently-labeled fatty acids. Decreased lipid storage in HILPDA-deficient macrophages could be rescued by inhibition of adipose triglyceride lipase (ATGL) and was associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency did not alter inflammatory and metabolic parameters, despite markedly reducing lipid accumulation in macrophages. Overall, we find that HILPDA is a lipid-induced physiological inhibitor of ATGL-mediated lipolysis in macrophages that uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Our data question the contribution of lipid droplet accumulation in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.
Project description:Obesity leads to a state of chronic low-grade inflammation that features accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid droplet accumulation in the development of obesity-induced adipose tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency markedly reduced intracellular lipid levels and accumulation of fluorescently-labeled fatty acids. Decreased lipid storage in HILPDA-deficient macrophages could be rescued by inhibition of adipose triglyceride lipase (ATGL) and was associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency did not alter inflammatory and metabolic parameters, despite markedly reducing lipid accumulation in macrophages. Overall, we find that HILPDA is a lipid-induced physiological inhibitor of ATGL-mediated lipolysis in macrophages that uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Our data question the contribution of lipid droplet accumulation in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.
Project description:Analysis of interscapular brown fat tissue of fasted mice to identify the possible impact of the lipid droplet protein Hilpda on thermogenesis. Tissues were isolated from genetically engineered mice with the Hilpda gene knocked out and Luciferase knocked in, and Hilpda WT counterparts.
Project description:Analysis of brown adipose tissue from Yin Yang 1 (YY1) brown fat specific knockout mice fed a high fat diet for 3 months. YY1 deficiency in brown adipose tissue leads to strong thermogenic deficiency. The goal was to identify the genes controlled by YY1 responsible of brown fat defective function.
Project description:Analysis of brown adipose tissue from Yin Yang 1 (YY1) brown fat specific knockout mice fed a high fat diet for 3 months. YY1 deficiency in brown adipose tissue leads to strong thermogenic deficiency. The goal was to identify the genes controlled by YY1 responsible of brown fat defective function. Control mice YY1flox/flox versus YY1flox/flox; Ucp1Cre were fed a high fat diet for 3 months
Project description:Abdominal aortic aneurysm (AAA) is a life-threatening vascular disease without effective medical therapies. Emerging evidences have suggested a crosstalk between adipose tissue and vascular cells and brown adipose tissue is beneficial for cardiovascular health. Nevertheless, whether brown remodeling of white adipose tissue would protect against AAA remains unclear. Here we showed that patients with AAA had a decreased browning level of adipose tissue and induction of adipose tissue browning significantly reduced AAA incidence and attenuated AAA development in mice. Using LC-MS/MS and proteomic analysis, we further identified Follistatin-like 1 (FSTL1) as a novel vessel-protective adipokine secreted by browning adipocytes. Mechanistically, FSTL1 inhibited VSMC apoptosis through DIP2A/AKT signaling. Furthermore, we demonstrated that adipocyte-specific deficiency of FSTL1 abrogated the protective effect of browning induction. Moreover, supplementation of FSTL1 either systemically or patched into hydrogel placing around abdominal aorta markedly limited aortic dilation and AAA progression. Our data suggest a protective role of adipose tissue browning and a novel batokine FSTL1 in the development of AAA, which may represent a novel intervention strategy for AAA.
Project description:Steap4, a highly expressed protein in adipose tissue, has been implicated in metabolic homeostasis. In this study, we generated adipocyte-specific Steap4-deficient mice and observed that Steap4 deficiency led to increased fat mass and severe insulin resistance in a high-fat diet model. Mass spectrometry analysis revealed two classes of Steap4 interactomes: mitochondrial proteins and proteins involved in spliceosome. RNA-seq analysis of white adipose tissue demonstrated that Steap4 deficiency altered RNA splicing patterns with enriched functions in mitochondria. While interactome and transcriptome data implicate a role of Steap4 in mitochondria, Steap4 deficiency indeed impaired mitochondrial respiratory chain complex activity resulting in mitochondrial dysfunction in white adipose tissue. Consistently, brown adipocyte-specific Steap4-deficient mice also showed impaired mitochondrial function, increased whitening of brown adipose tissue, reduced energy expenditure, and exacerbated insulin resistance under HFD conditions. Overall, our findings elucidate the critical role of Steap4 in regulating adipocyte thermogenesis and energy expenditure by modulating mitochondrial function.