Crocin Improves Endothelial Mitochondrial Dysfunction via GPx1/ROS/KCa3.1 Signal Axis in Diabetes

Xuemei Li,Yang Liu,Huike Yang,Xinlei Li,Xiaohong Lv,Yafang Zhang,Xingchi Du,Anqiang Cao,Qing Wu,Ciren Laba,Hua Chun,Luodan Wang,Jiwei Zhu,Chao Li

doi:10.3389/fcell.2021.651434

Abstract

Mitochondrial dysfunction contributes to excessive reactive oxygen species (ROS) generation, which is a dramatic cause to promote endothelial dysfunction in diabetes. It was previously demonstrated that crocin protected the endothelium based on its diverse medicinal properties, but its effect on the mitochondrion and the potential mechanism are not fully understood. In this study, mitochondrial function was analyzed during the process of excessive ROS generation in high glucose (HG)-cultured human umbilical vein endothelial cells (HUVECs). The role played by KCa3.1 was further investigated by the inhibition and/or gene silence of KCa3.1 in this process. In addition, nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase 2 (NOX2), superoxide dismutase 1 (SOD1), and glutathione peroxidase 1 (GPx1) were also detected in this study. Our data showed that crocin improved mitochondrial dysfunction and maintained normal mitochondrial morphology by enhancing the mitochondrial membrane potential (MMP), mitochondrial mass, and mitochondrial fusion. Furthermore, KCa3.1 was confirmed to be located in the mitochondrion, and the blockade and/or silencing of KCa3.1 improved mitochondrial dysfunction and reduced excessive ROS generation but did not affect NOX2 and/or the SOD1 system. Intriguingly, it was confirmed that KCa3.1 expression was elevated by ROS overproduction in the endothelium under HG and/or diabetes conditions, while crocin significantly suppressed this elevation by promoting GPx1 and subsequently eliminating ROS generation. In addition, crocin enhanced CD31, thrombomodulin (TM), and p-/t-endothelial nitric oxide synthase (eNOS) expressions as well as NO generation and decreased vascular tone. Hence, crocin improved mitochondrial dysfunction through inhibiting ROS-induced KCa3.1 overexpression in the endothelium, which in turn reduced more ROS generation and final endothelial dysfunction in diabetes.

Highlights

Endothelial cells, viewed as a barrier structure between blood and vessel wall/tissues, function actively in maintaining the vascular homeostasis system under normal conditions (Favero et al, 2014)
Representative TEM images illustrated that high glucose (HG) induced serious apoptosis and mitochondrial damage compared to the control and/or normal groups (Figure 1G)
Mitochondria are a dominant source of cellular reactive oxygen species (ROS) in tissue (Dan Dunn et al, 2015), and hyperglycemia-induced mitochondrial dysfunction is a dominant cause of excessive ROS production in diabetes (Widlansky and Hill, 2018)

Summary

Introduction

Endothelial cells, viewed as a barrier structure between blood and vessel wall/tissues, function actively in maintaining the vascular homeostasis system under normal conditions (Favero et al, 2014). They are able to crucially regulate vascular tone, structure, and other various biological events by the production of a wide range of biological factors (Deanfield et al, 2007; Rajendran et al, 2013; McLaughlin et al, 2018). Mitochondrial dysfunction is a dominant cause of more ROS production, leading to the development of endothelial dysfunction in diabetes (Widlansky and Hill, 2018)

Methods

Results

Conclusion