Project description:We have identified molecular-level alternations in different adipose depots (thigh, visceral and subcutaneous) of Asian Indians (both male and female) suffering from type-2 diabetes as compared to age and BMI matched normal glucose tolerant subjects by functional analysis of differentially expressed genes, and correlation of gene expression estimates with measured intermediate traits associated with T2D and its related co-morbidities (Hb1Ac, HOMA-B, HOMA-R, NEFA, Triglyceride, Total Cholesterol, HDL, LDL, VLDL, Leptin, Adiponectin, TNF-α, Serum- Creatinine, IL-6, High sensitivity - serum-creatinine (hs-CRP) and also size of adipocytes). Funding: Grant Id: 5/4/8/2012-RMC Grant title: Clinical, Biochemical and Cellular Correlates of Transcriptome of Adipose Tissue Among Type-2 Diabetics Name of the funding source: Indian Council for Medical Research
Project description:A robust system using disease relevant cells to systematically evaluate the role in diabetes for loci identified through genome wide association studies (GWAS) is urgently needed. Toward this goal, we created isogenic mutant human embryonic stem cell (hESC) lines in GWAS-identified candidate diabetes genes including CDKAL1, KCNQ1 and KCNJ11, and used directed differentiation to evaluate the function of derivative human beta-like cells. The mutations did not affect the generation of insulin+ cells, but impaired insulin secretion both in vitro and in vivo, coinciding with defective glucose homeostasis. CDKAL1-/- insulin+ cells also displayed hypersensitivity to lipotoxicity. A high-content chemical screen identified a candidate drug that rescued CDKAL1-/--specific defects by inhibiting the AP1 (FOS/JUN) pathway. These studies establish a platform using isogenic hESCs to evaluate the function of GWAS-identified loci, and identify a drug candidate that rescues gene-specific defects, paving the way to precision therapy of metabolic diseases.A robust system using disease relevant cells to systematically evaluate the role in diabetes for loci identified through genome wide association studies (GWAS) is urgently needed. Toward this goal, we created isogenic mutant human embryonic stem cell (hESC) lines in GWAS-identified candidate diabetes genes including CDKAL1, KCNQ1 and KCNJ11, and used directed differentiation to evaluate the function of derivative human beta-like cells. The mutations did not affect the generation of insulin+ cells, but impaired insulin secretion both in vitro and in vivo, coinciding with defective glucose homeostasis. CDKAL1-/- insulin+ cells also displayed hypersensitivity to lipotoxicity. A high-content chemical screen identified a candidate drug that rescued CDKAL1-/--specific defects by inhibiting the AP1 (FOS/JUN) pathway. These studies establish a platform using isogenic hESCs to evaluate the function of GWAS-identified loci, and identify a drug candidate that rescues gene-specific defects, paving the way to precision therapy of metabolic diseases.
Project description:Global transcript profiling to identify differentially expressed skeletal muscle genes in insulin resistance, a major risk factor for Type II (non-insulin-dependent) diabetes mellitus. Compared gene expression profiles of skeletal muscle tissues from 18 insulin-sensitive versus 17 insulin-resistant equally obese, non-diabetic Pima Indians. Keywords: other
Project description:Recent genome-wide association studies (GWAS) identified Dusp8, a dual-specificity phosphatase targeting MAP kinases, as type 2 diabetes risk gene. Here, we unravel Dusp8 as gatekeeper in the hypothalamic control of glucose homeostasis in mice and humans. Male but not female Dusp8 loss-of-function mice, either with global or CRH neuron-specific deletion, had impaired systemic glucose tolerance and insulin sensitivity when exposed to high-fat diet (HFD). Mechanistically, we found impaired hypothalamic–pituitary–adrenal (HPA) axis feedback, blunted sympathetic responsiveness, and chronically elevated corticosterone levels driven by hypothalamic hyperactivation of Jnk signaling. Accordingly, global Jnk1 ablation, AAV-mediated Dusp8 overexpression in the mediobasal hypothalamus, or metyrapone-induced chemical adrenalectomy rescued the impaired glucose homeostasis of male Dusp8 KO mice, respectively. This sex-specific and rheostatic role of murine Dusp8 in governing hypothalamic Jnk signaling, insulin sensitivity and systemic glucose tolerance was consistent with fMRI data in human volunteers that revealed an association of the DUSP8 rs2334499 risk variant with hypothalamic insulin resistance in men. In summary, our findings suggest GWAS-identified gene Dusp8 as novel hypothalamic factor that plays a functional role in the etiology of type 2 diabetes.
Project description:Single-cell RNA-seq (scRNA-seq) of pancreatic islets have reported on α- and β-cell gene expression in mice and subjects of predominantly European ancestry. We aimed to assess these findings in East-Asian islet-cells. 448 islet-cells were captured from three East-Asian non-diabetic subjects for scRNA-seq. Hierarchical clustering using pancreatic cell lineage genes was used to assign cells into cell-types. Differentially expressed transcripts between α- and β-cells were detected using ANOVA and in silico replications of mouse and human islet cell genes were performed. We identified 118 α, 105 β, 6 δ endocrine cells and 47 exocrine cells. Besides INS and GCG, 26 genes showed differential expression between α- and β-cells. 10 genes showed concordant expression as reported in rodents, while FAM46A was significantly discordant. Comparing our East-Asian data with data from primarily European subjects, we replicated several genes implicated in nuclear receptor activations, acute phase response pathway, glutaryl-CoA/tryptophan degradations and EIF2/AMPK/mTOR signaling. Additionally, we identified protein ubiquitination to be associated among East-Asian β-cells. We report on East-Asian α- and β-cell gene signatures and substantiate several genes/pathways. We identify expression signatures in East-Asian β-cells that perhaps reflects increased susceptibility to cell-death and warrants future validations to fully appreciate their role in East-Asian diabetes pathogenesis.