Increased Interaction With Insulin Receptor Substrate 1, a Novel Abnormality in Insulin Resistance and Type 2 Diabetes

Abstract

Insulin receptor substrate 1 (IRS1) is a key mediator of insulin signal transduction. Perturbations involving IRS1 complexes may lead to the development of insulin resistance and type 2 diabetes (T2D). Surprisingly little is known about the proteins that interact with IRS1 in humans under health and disease conditions. We used a proteomic approach to assess IRS1 interaction partners in skeletal muscle from lean healthy control subjects (LCs), obese insulin-resistant nondiabetic control subjects (OCs), and participants with T2D before and after insulin infusion. We identified 113 novel endogenous IRS1 interaction partners, which represents the largest IRS1 interactome in humans and provides new targets for studies of IRS1 complexes in various diseases. Furthermore, we generated the first global picture of IRS1 interaction partners in LCs, and how they differ in OCs and T2D patients. Interestingly, dozens of proteins in OCs and/or T2D patients exhibited increased associations with IRS1 compared with LCs under the basal and/or insulin-stimulated conditions, revealing multiple new dysfunctional IRS1 pathways in OCs and T2D patients. This novel abnormality, increased interaction of multiple proteins with IRS1 in obesity and T2D in humans, provides new insights into the molecular mechanism of insulin resistance and identifies new targets for T2D drug development.

Hyperglycemia-induced changes in miRNA expression patterns in epicardial adipose tissue of piglets

“…It is well known that insulin signaling is implicated in the regulation of adipocytes biology. Furthermore, an activation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB)/Akt by the insulin/insulinlike growth factor 1 receptor (IRS1) protein appears to be important in the mechanism of glucose uptake in adipocytes (Rodrigues et al 2007, Caruso et al 2014. We observed a significant increased expression of miR-193a-3p, suggesting that, at least in EAT, this miRNA may be involved in the initial cellular responses to hyperglycemia (Kato et al 2009).…”

Spatial and Temporal Regulation of Receptor Tyrosine Kinase Activation and Intracellular Signal Transduction

“…Immune-precipitates of IRS1 from homogenates of muscle from biopsies of glucose-tolerant lean, glucose-tolerant obese, and type 2 diabetic patients revealed 122 IRS-1 interacting proteins (81). Of these, PI3K α and β subunits showed an insulin-dependent increased association with IRS1 in muscle of lean but not that of the obese or type 2 diabetic subjects.…”

Quantitative proteomics reveals novel protein interaction partners of PP2A catalytic subunit in pancreatic β-cells

“…Bead eluates were resolved by 4–15% SDS-PAGE. For each lane, five slices (250–150 kDa, 150–75 kDa, 75–50 kDa, 50–25 kDa, and 25–10 kDa) were excised and subjected to in-gel trypsin digestion, peptide purification and HPLC-ESI-MS/MS analysis using an LTQ Orbitrap Elite as described[11]. Peptide/protein identification and quantification were performed using the MaxQuant, one of the popular quantitative proteomics software packages [18].…”

“…In addition, PP2Ac was identified as an interaction partner of insulin receptor substrate-1 (IRS1) in murine HL-1 cardiomyocytes[10]. More recently, we have demonstrated that PP2Ac interacted with IRS1 in skeletal muscle of lean healthy controls, and this interaction is increased in insulin resistant obese nondiabetic controls and type 2 diabetic patients [11]. It is well established that chronic exposure of pancreatic β-cells to high glucose (HG; glucotoxicity) leads to metabolic dysfunction and demise [12].…”

“…Recently, we developed a straightforward, label-free approach combining co-IP with HPLC-ESI-MS/MS, without the use of protein overexpression or protein tags, to investigate changes in the abundance of endogenous proteins associated with a bait protein[17]. More recently, we have optimized this label-free approach, and discovered novel IRS-1 interaction partners in skeletal muscle from lean healthy, obese non-diabetic, and type 2 diabetic patients[11]. In the present work, we applied this proteomics approach to identify protein interaction partners of PP2Ac in pancreatic islet β-cells exposed to basal (2.5 mM) and glucotoxic (25 mM) conditions.…”