Work done over the last funding period has demonstrated that ceramide production and clustering of membrane rafts (MR) (formerly lipid rafts) drive aggregation of NADPH oxidase (Nox) subunits together with other regulatory molecules in the membrane of endothelial cells (ECs) forming a MR redox signaling platform. This signaling platform produces superoxide to regulate coronary endothelial function. This competitive renewal now seeks to elucidate the molecular mechanisms mediating the formation and function of such MR signaling platforms. The hypothesis being tested is that a rapid fusion of membrane proximal lysosomes to plasma membrane via the SNARE-centered exocytic machinery mediates translocation of ASMase, local ceramide production, and consequent formation of MR redox signaling platforms in coronary arterial endothelial cells. This lysosome-MR redox signalosome contributes to endothelial dysfunction in response to activation of death receptors and other danger signals.
Specific Aim 1 will determine whether the formation of MR redox signaling platforms are mediated by a rapid fusion of membrane proximal lysosomes to plasma membrane via a SNARE- centered exocytic machinery in coronary ECs.
Specific Aim 2 will identify the topographic characteristics of lysosome-MR signalosomes in coronary ECs using scanning and immunogold electron microscopy and determine possible interactions of different molecules.
Specific Aim 3 will determine the functionality of the lysosome MR signalosomes in coronary ECs with a focus on interactions of ASMase activity and Nox activation.
Specific Aim 4 will determine whether the formation of such lysosome MR signalosomes via the SNARE-centered exocytic machinery contributes to endothelial dysfunction in the intact coronary arterial endothelium. These proposed studies will elucidate the molecular mechanisms mediating the trafficking of intracellular organelles and molecules to cell plasma membrane for transmembrane signaling. The results will reveal a novel lysosomal function serving as a signaling organelle in ECs, which may importantly contribute to the formation of MR redox signaling platform and thereby to the regulation of endothelial function under physiological and pathological conditions.
This grant proposal seeks to study a novel signaling mechanism by which a membrane signaling complex is formed, which is referred to as membrane raft redox signaling platform. This signaling platform will regulate the function of heart arteries and blood flow. The major focus of the proposed studies is to determine whether or how a small functional body-lysosome within endothelial cells of the heart arteries moves to cell membrane to help form signaling platforms. The findings will importantly contribute to our understanding of the mechanisms responsible for contraction of the heart arteries and therefore may help develop new therapeutic strategies for coronary arterial disease to prevent heart attack in the future.
|Chen, Yang; Li, Xiang; Boini, Krishna M et al. (2015) Endothelial Nlrp3 inflammasome activation associated with lysosomal destabilization during coronary arteritis. Biochim Biophys Acta 1853:396-408|
|Li, Xiang; Xu, Ming; Pitzer, Ashley L et al. (2014) Control of autophagy maturation by acid sphingomyelinase in mouse coronary arterial smooth muscle cells: protective role in atherosclerosis. J Mol Med (Berl) 92:473-85|
|Boini, Krishna M; Xia, Min; Abais, Justin M et al. (2014) Activation of inflammasomes in podocyte injury of mice on the high fat diet: Effects of ASC gene deletion and silencing. Biochim Biophys Acta 1843:836-45|
|Li, Xiang; Zhang, Yang; Xia, Min et al. (2014) Activation of Nlrp3 inflammasomes enhances macrophage lipid-deposition and migration: implication of a novel role of inflammasome in atherogenesis. PLoS One 9:e87552|
|Xia, Min; Boini, Krishna M; Abais, Justine M et al. (2014) Endothelial NLRP3 inflammasome activation and enhanced neointima formation in mice by adipokine visfatin. Am J Pathol 184:1617-28|
|Xu, Ming; Li, Xiao-Xue; Chen, Yang et al. (2014) Enhancement of dynein-mediated autophagosome trafficking and autophagy maturation by ROS in mouse coronary arterial myocytes. J Cell Mol Med 18:2165-75|
|Zhang, Yang; Xu, Ming; Xia, Min et al. (2014) Defective autophagosome trafficking contributes to impaired autophagic flux in coronary arterial myocytes lacking CD38 gene. Cardiovasc Res 102:68-78|
|Wang, Mi; Abais, Justine M; Meng, Nan et al. (2014) Upregulation of cannabinoid receptor-1 and fibrotic activation of mouse hepatic stellate cells during Schistosoma J. infection: role of NADPH oxidase. Free Radic Biol Med 71:109-20|
|Abais, Justine M; Xia, Min; Li, Guangbi et al. (2014) Contribution of endogenously produced reactive oxygen species to the activation of podocyte NLRP3 inflammasomes in hyperhomocysteinemia. Free Radic Biol Med 67:211-20|
|Xia, Min; Conley, Sabena M; Li, Guangbi et al. (2014) Inhibition of hyperhomocysteinemia-induced inflammasome activation and glomerular sclerosis by NLRP3 gene deletion. Cell Physiol Biochem 34:829-41|
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