Homocysteine facilitates LOX-1 activation and endothelial death through the PKC{beta} and SIRT1/HSF1 mechanism: relevance to human Hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) is one of the major risk factors for cardiovascular diseases. A high concentration of Homocysteine (Hcy) induces endothelial dysfunction by activating endothelial oxidative stress. LOX-1 plays a vital role in regulating the progression of atherosclerotic lesions. LOX-1 activation causes endothelial apoptosis and inflammation. The mechanism is still unclear as to whether Hcy affects human endothelial LOX-1 expression. LOX-1 expression level was confirmed by Western blotting assay in Hcy-treated endothelial cells. L-methionine was used for HHct induction in animals. Our results suggested that Hcy increased PKCβ activation to enhance the LOX-1 expression level. The up-regulation of PKCβ phosphorylation subsequently causes ROS formation and SIRT1 degradation through a proteasome-dependent mechanism, thereby mitigating the SIRT1 by de-acetylating the heat shock transcription factor 1 (HSF1). We also found that NOX2 is a key NOX isoform responsible for the Hcy-caused ROS formation. The over-expression of SIRT1 and HSF1 reduced the Hcy-induced LOX-1 activation. Silencing the PKCβ function also reduced the LOX-1 activation and endothelial apoptosis caused by Hcy. Our hypothesis was supported by analyzing the data from methionine-induced HHcy animals. Our data indicate a new direction for LOX-1 regulation by the modulation of the PKCβ/NADPH oxidase/ SIRT1/HSF1 mechanism. Our findings might provide a novel idea for developing new ...
Source: Clinical Science - Category: Biomedical Science Authors: Source Type: research