Mitochondrial CD36 Regulates Lipid Metabolism and Superoxide Production in Endothelial Cells Under Hyperglycemic and obesogenic Conditions

Diabetes is a chronic condition with high blood sugar, increasing the risk of cardiovascular events by 2 to 4 times. The vascular endothelium plays a crucial role in regulating vascular tone and maintaining vascular homeostasis. In diabetes, endothelial damage can occur through insulin resistance, hyperglycemia, and low-grade systemic inflammation, independent of other cardiovascular risk factors. The cluster of differentiation 36 (CD36), a fatty acid translocase, scavenger receptor, and glycoprotein, has been shown to be upregulated in obesity and in response to elevated glucose levels. Notably, CD36 has also been identified in mitochondria, suggesting a potential role in cellular respiration. However, the role of mitochondrial CD36 (mitoCD36) in endothelial cells' lipid metabolism has not yet been studied. To address this knowledge gap, we exposed human adipose microvascular endothelial cells (HAMECs) to elevated glucose (200mg/dl), fatty acids (FAs), or both simultaneously for 72 hours to mimic the conditions of obesity and hyperglycemia. Our data revealed that cells treated with glucose and FAs together exhibited significantly increased mitochondrial superoxide production compared to cells treated with glucose or FAs alone. Superoxide production was significantly reduced in glucose and FA-treated cells when CD36 was downregulated using siRNA. Furthermore, glucose significantly upregulated total-CD36 protein expression after 72 hours of treatment, however, this increase was not observed in membrane-localized CD36. Since membrane CD36 expression was not upregulated by glucose treatment, we next quantified CD36 expression in the pure mitochondrial fraction isolated from HAMECs using TOM40-based magnetic cell sorting. CD36 expression was increased in the mitochondrial fraction of glucose-treated cells, which may result in alterations in mitochondrial respiration following sustained high glucose levels. These findings were further confirmed by colocalization of MitoTtracker and CD36. Our study suggests that mitochondrial CD36 plays a pivotal role in oxidative stress in endothelial cells exposed to sustained glucose levels in vitro. Future studies will explore the molecular mechanisms underlying the increase in mitochondrial CD36 expression in response to glucose and its effects on endothelial cell respiration during fatty acid exposure. Institutional Development Award (IDeA) from 365 National Institute of General Medical Sciences Grant 2P20GM113125; University of Delaware Research Funds. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.