ROCK2 associates with lectin-like oxidized LDL receptor-1 and mediates oxidized LDL-induced IL-8 production

Abstract

Oxidatively modified low-density lipoprotein (OxLDL) is a contributing factor of endothelial dysfunction, an early cellular event during atherogenesis. In endothelial cells, OxLDL has been shown to stimulate proinflammatory responses, increase lipid accumulation, and induce the expression of adhesion and extracellular matrix degrading molecules. The primary receptor for OxLDL on endothelial cells has been identified as a member of the scavenger receptor family called lectin-like OxLDL receptor-1 (LOX-1). A number of studies on LOX-1 have implicated its role in multiple cardiovascular diseases including atherosclerosis. To better understand the molecular mechanisms underlying the role of LOX-1 in endothelial cells, we identified interacting proteins in an affinity-purified LOX-1 receptor complex from human aortic endothelial HAECT cells by mass spectrometry. Two molecules involved in Rho signaling pathway, ARHGEF1 and ROCK2, were identified, and their associations with LOX-1 were confirmed in reciprocal immunoprecipitation studies. Particularly, ROCK2 was found to dynamically associate with LOX-1 in the presence of OxLDL. In addition, OxLDL treatment stimulated ROCK2 catalytic activity, and ROCK2 inhibition attenuated NF-kappaB activation and IL-8 production resulting from OxLDL activation of LOX-1. In summary, a functional proteomics approach has enabled us to identify novel LOX-1 interactors that potentially contribute to the cellular and signaling functions of LOX-1.

Lupus high-density lipoprotein induces proinflammatory responses in macrophages by binding lectin-like oxidised low-density lipoprotein receptor 1 and failing to promote activating transcription factor 3 activity

“…Stimulation of LOX1R has been linked to activation of ROCK1/2, which then activates NFκB 20. Given that ROCK1/2 are serine/threonine kinases and that ATF3 contains a threonine (Thr-162) phosphorylation site, we examined the role of ROCK1/2 on SLE HDL-induced inflammation and ATF3 activity 21…”

Molecular Biology of Atherosclerosis

“…ARHGEF1 and MMP1 together activate RhoA (not found in the complex) which then activates ROCK2. Direct phosphorylation by ROCK2 inhibits eNOS and PI3K activity (1158). RhoA may also suppress PI3K through an effect on the actin cytoskeleton.…”

Rock the Rock of Atherosclerosis

“…A number of studies on LOX-1 have implicated its role in multiple cardiovascular diseases including atherosclerosis. Mattaliano et al [19] recently demonstrated that, ROCK2 dynamically interacts with LOX-1 in the presence of oxLDL. In addition, oxLDL treatment stimulated ROCK2 catalytic activity, and ROCK2 inhibition (either by Y27632 or fasudil) attenuated oxLDL induced CXCL2 level and IL-8 secretion.…”