| First Author | Myers RB | Year | 2016 |
| Journal | Am J Physiol Heart Circ Physiol | Volume | 310 |
| Issue | 11 | Pages | H1748-59 |
| PubMed ID | 27037370 | Mgi Jnum | J:234809 |
| Mgi Id | MGI:5790904 | Doi | 10.1152/ajpheart.00051.2016 |
| Citation | Myers RB, et al. (2016) Deletion of thioredoxin-interacting protein improves cardiac inotropic reserve in the streptozotocin-induced diabetic heart. Am J Physiol Heart Circ Physiol 310(11):H1748-59 |
| abstractText | Although the precise pathogenesis of diabetic cardiac damage remains unclear, potential mechanisms include increased oxidative stress, autonomic nervous dysfunction, and altered cardiac metabolism. Thioredoxin-interacting protein (Txnip) was initially identified as an inhibitor of the antioxidant thioredoxin but is now recognized as a member of the arrestin superfamily of adaptor proteins that classically regulate G protein-coupled receptor signaling. Here we show that Txnip plays a key role in diabetic cardiomyopathy. High glucose levels induced Txnip expression in rat cardiomyocytes in vitro and in the myocardium of streptozotocin-induced diabetic mice in vivo. While hyperglycemia did not induce cardiac dysfunction at baseline, beta-adrenergic challenge revealed a blunted myocardial inotropic response in diabetic animals (24-wk-old male and female C57BL/6;129Sv mice). Interestingly, diabetic mice with cardiomyocyte-specific deletion of Txnip retained a greater cardiac response to beta-adrenergic stimulation than wild-type mice. This benefit in Txnip-knockout hearts was not related to the level of thioredoxin activity or oxidative stress. Unlike the beta-arrestins, Txnip did not interact with beta-adrenergic receptors to desensitize downstream signaling. However, our proteomic and functional analyses demonstrated that Txnip inhibits glucose transport through direct binding to glucose transporter 1 (GLUT1). An ex vivo analysis of perfused hearts further demonstrated that the enhanced functional reserve afforded by deletion of Txnip was associated with myocardial glucose utilization during beta-adrenergic stimulation. These data provide novel evidence that hyperglycemia-induced Txnip is responsible for impaired cardiac inotropic reserve by direct regulation of insulin-independent glucose uptake through GLUT1 and plays a role in the development of diabetic cardiomyopathy. |
