Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insufficient insulin secretion and reduced pancreatic beta cell mass are hallmarks of type 2 diabetes (T2DM). Here, we confirm that a previously identified polymorphism (rs2295490/Q84R) in exon 2 of the pseudokinase-encoding gene tribbles 3 (TRB3) is associated with an increased risk for T2DM in 2 populations of people of mixed European descent. Carriers of the 84R allele had substantially reduced plasma levels of C-peptide, the product of proinsulin processing to insulin, suggesting a role for TRB3 in beta cell function. Overexpression of TRB3 84R in mouse beta cells, human islet cells, and the murine beta cell line MIN6 revealed reduced insulin exocytosis, associated with a marked reduction in docked insulin granules visualized by electron microscopy. Conversely, knockdown of TRB3 in MIN6 cells restored insulin secretion and expression of exocytosis genes. Further analysis in MIN6 cells demonstrated that TRB3 interacted with the transcription factor ATF4 and that this complex acted as a competitive inhibitor of cAMP response element-binding (CREB) transcription factor in the regulation of key exocytosis genes. In addition, the 84R TRB3 variant exhibited greater protein stability than wild-type TRB3 and increased binding affinity to Akt. Mice overexpressing TRB3 84R in beta cells displayed decreased beta cell mass, associated with reduced proliferation and enhanced apoptosis rates. These data link a missense polymorphism in human TRB3 to impaired insulin exocytosis and thus increased risk for T2DM.
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PMID:The pseudokinase tribbles homolog 3 interacts with ATF4 to negatively regulate insulin exocytosis in human and mouse beta cells. 2059 69

Endoplasmic reticulum stress has been linked to insulin resistance in multiple tissues but the role of endoplasmic reticulum stress in skeletal muscle has not been explored. Endoplasmic reticulum stress has been reported to increase tribbles 3 expression in multiple cell lines. Here, we report that high-fat feeding in mice, and obesity and type 2 diabetes in humans significantly increases tribbles 3 and endoplasmic reticulum stress markers in skeletal muscle. Overexpression of tribbles 3 in C2C12 myotubes and mouse tibialis anterior muscles significantly impairs insulin signalling. Incubation of C2C12 cells and mouse skeletal muscle with endoplasmic reticulum stressors thapsigargin and tunicamycin increases tribbles 3 and impairs insulin signalling and glucose uptake, effects reversed in cells overexpressing RNAi for tribbles 3 and in muscles from tribbles 3 knockout mice. Furthermore, tribbles 3 knockout mice are protected from high-fat diet-induced insulin resistance in skeletal muscle. These data demonstrate that tribbles 3 mediates endoplasmic reticulum stress-induced insulin resistance in skeletal muscle.
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PMID:Tribbles 3 mediates endoplasmic reticulum stress-induced insulin resistance in skeletal muscle. 2369 65