Gram positive infections make up ~50% of all acute lung injury cases with Streptococcus pneumonia infections accounting for 45% of all community-acquired pneumonia (CAP) cases. CAP is accompanied by extensive permeability edema, characterized by a disruption in endothelial barrier integrity. A major factor in the severity of CAP is the secretion of bacterial virulence factors predominantly pneumolysin (PLY) and family member listeriolysin-0 (LLO). These gram positive virulence factors make plasma membrane pores that cause a Ca2+-influx in various cell types, stimulate host PLC activity and as we have recently shown, activate protein kinase C alpha (PKCalpha). Previously we showed that inhibition of PKCalpha is barrier protective against these gram-positive virulence factors. Further, this is due, at least in part, to the ability of PKC alpha to increase production of reactive oxygen- and -nitrogen species associated. LLO induces eNOS uncoupling, enhances peroxynitrite generation, and causes an increase in RhoA and Rac 1 nitration resulting in activation of the former and inhibition of the latter. This project will focus on distinct mechanisms of eNOS uncoupling that we hypothesize occurs via the PKCalpha mediated phosphorylation of eNOS at Thr495 rather than through increased ADMA generation (see Project 1). From our previously published studies and new preliminary data, the overall hypothesis that we will test in this proposal is that inhibition of PKCalpha leads to the enhanced release of NO from eNOS which stimulates the S-nitrosylation of RhoA and Rac 1. This modification leads to RhoA inhibition and Rac1 activation and EC barrier protection.
Specific Aim 1 will determine the mechanism by which PKCalpha mediates PLY/LLO driven eNOS uncoupling.
Specific Aim 2 will determine if PKCalpha-mediated increases in NO signaling attenuate the endothelial barrier disruption induced by PLY and LLO and whether this occurs via the S-nitrosylation of RhoA and Rac1.
This Aim will also identify the specific cytokine residues on RhoA and Rac1 that are nitrosylated.
Specific Aim 3 will determine the relative effects of reducing PKCalpha activity and directly enhancing RhoA and Rac1 Snitrosylation in protecting the endothelial barrier during ALI in vivo.
The overall goal of this Project 4 is to further our understanding of the molecular mechanisms by which the Gram + exotoxins disrupt the pulmonary endothelial cell barrier. Specifically we will investigate novel mechanisms and therapeutics controling the function of eNOS and ultimately the balance of RhoA/Rac activity in the endothelial hyperpermeability associated with acute lung injury (ALI).
|Sun, Xutong; Kumar, Sanjiv; Sharma, Shruti et al. (2014) Endothelin-1 induces a glycolytic switch in pulmonary arterial endothelial cells via the mitochondrial translocation of endothelial nitric oxide synthase. Am J Respir Cell Mol Biol 50:1084-95|
|Aggarwal, Saurabh; Gross, Christine M; Rafikov, Ruslan et al. (2014) Nitration of tyrosine 247 inhibits protein kinase G-1? activity by attenuating cyclic guanosine monophosphate binding. J Biol Chem 289:7948-61|
|Gonzales, Joyce N; Gorshkov, Boris; Varn, Matthew N et al. (2014) Protective effect of adenosine receptors against lipopolysaccharide-induced acute lung injury. Am J Physiol Lung Cell Mol Physiol 306:L497-507|
|Xu, Yiming; An, Xiaofei; Guo, Xin et al. (2014) Endothelial PFKFB3 plays a critical role in angiogenesis. Arterioscler Thromb Vasc Biol 34:1231-9|
|Gross, Christine M; Aggarwal, Saurabh; Kumar, Sanjiv et al. (2014) Sox18 preserves the pulmonary endothelial barrier under conditions of increased shear stress. J Cell Physiol 229:1802-16|
|Chen, Feng; Yu, Yanfang; Haigh, Steven et al. (2014) Regulation of NADPH oxidase 5 by protein kinase C isoforms. PLoS One 9:e88405|
|Czikora, István; Alli, Abdel; Bao, Hui-Fang et al. (2014) A novel tumor necrosis factor-mediated mechanism of direct epithelial sodium channel activation. Am J Respir Crit Care Med 190:522-32|
|Chen, Feng; Kumar, Sanjiv; Yu, Yanfang et al. (2014) PKC-dependent phosphorylation of eNOS at T495 regulates eNOS coupling and endothelial barrier function in response to G+ -toxins. PLoS One 9:e99823|
|Gonzales, Joyce N; Kim, Kyung-mi; Zemskova, Marina A et al. (2014) Low anticoagulant heparin blocks thrombin-induced endothelial permeability in a PAR-dependent manner. Vascul Pharmacol 62:63-71|
|Rafikov, Ruslan; Dimitropoulou, Christiana; Aggarwal, Saurabh et al. (2014) Lipopolysaccharide-induced lung injury involves the nitration-mediated activation of RhoA. J Biol Chem 289:4710-22|
Showing the most recent 10 out of 26 publications