Mechanism of PKC activity affecting the adhesion reaction of endothelial cells with monocytes

Molecular mechanisms of hydrogen sulfide against uremic accelerated atherosclerosis through cPKCβII/Akt signal pathway

Background

Cardiovascular disease is the most common complication and leading cause of death in maintenance hemodialysis patients. The protection mechanism of hydrogen sulfide (H₂S) and the specific role of conventional protein kinase C βII (cPKCβII)/Akt signaling pathway in the formation of atherosclerosis is still controversial.

Methods

8-week-old male ApoE^−/− mice were treated with 5/6 nephrectomy and high-fat diet to make uremia accelerated atherosclerosis (UAAS) model. Mice were divided into normal control group (control group), sham operation group (sham group), UAAS group, L-cysteine group (UAAS+L-cys group), sodium hydrosulfide group (UAAS+NaHS group), and propargylglycine group (UAAS+PPG group). Western blot was used to detect cPKCβII activation, Akt phosphorylation and endothelial nitric oxide synthase (eNOS) expression in mice aorta.

Results

The membrane translocation of cPKCβII in UAAS group was higher than sham group, and L-cys or NaHS injection could suppress the membrane translocation, but PPG treatment resulted in more membrane translocation of cPKCβII (P < 0.05, n = 6 per group). Akt phosphorylation and the eNOS expression in UAAS group was lower than sham group, and L-cys or NaHS injection could suppress the degradation of Akt phosphorylation and the eNOS expression, but PPG treatment resulted in more decrease in the Akt phosphorylation and the eNOS expression (P < 0.05, n = 6 per group).

Conclusion

Endogenous cystathionine-γ-lyase (CSE)/H₂S system protected against the formation of UAAS via cPKCβII/Akt signal pathway. The imbalance of CSE/H₂S system may participate in the formation of UAAS by affecting the expression of downstream molecule eNOS, which may be mediated by cPKCβII/Akt signaling pathway.

Rapamycin inhibits ox-LDL-induced inflammation in human endothelial cells in vitro by inhibiting the mTORC2/PKC/c-Fos pathway

Rapamycin and its derivative possess anti-atherosclerosis activity, but its effects on adhesion molecule expression and macrophage adhesion to endothelial cells during atherosclerosis remain unclear. In this study we explored the effects of rapamycin on ox-LDL-induced adhesion molecule expression and macrophage adhesion to endothelial cells in vitro and the underlying mechanisms. Ox-LDL (6-48 μg/mL) dose-dependently increased the protein levels of two adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and E-selectin, in human umbilical vein endothelial cells (HUVECs), whereas pretreatment with rapamycin (1-10 μmol/L) dose-dependently inhibited ox-LDL-induced increase in the adhesion molecule expression and macrophage adhesion to endothelial cells. Knockdown of mTOR or rictor, rather than raptor, mimicked the effects of rapamycin. Ox-LDL (100 μg/mL) time-dependently increased PKC phosphorylation in HUVECs, which was abolished by rapamycin or rictor siRNA. Pretreatment with PKC inhibitor staurosporine significantly reduced ox-LDL-stimulated adhesion molecule expression and macrophage adhesion to endothelial cells, whereas pretreatment with PKC activator PMA/TPA attenuated the inhibitory effect of rapamycin on adhesion molecule expression. Ox-LDL (100 μg/mL) time-dependently increased c-Fos levels in HUVECs, and pretreatment with rapamycin or rictor siRNA significantly decreased expression of c-Fos. Knockdown of c-Fos antagonized ox-LDL-induced adhesion molecule expression and macrophage adhesion to endothelial cells. Our results demonstrate that rapamycin reduces ox-LDL-stimulated adhesion molecule expression and macrophage adhesion to endothelial cells by inhibiting mTORC2, but not mTORC1, and mTORC2 acts through the PKC/c-Fos signaling pathway.

15-oxoeicosatetraenoic acid mediates monocyte adhesion to endothelial cell

Background

A great number of studies reported that 12/15-lipoxygenase (12/15-LO) played an important role in atherosclerosis. And its arachidonic acid(AA) metabolite, 15(S)-hydroperoxy-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15(S)-HETE), is demonstrated to mediate endothelial dysfunction. 15-oxo-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15-oxo-ETE) was formed from 15-hydroxyprostaglandin dehydrogenase (PGDH)-mediated oxidation of 15(S)-HETE. However, relatively little is known about the biological effects of 15-oxo-ETE in cardiovascular disease. Here, we explore the likely role of 15-lipoxygenase (LO)-1-mediated AA metabolism,15-oxo-ETE, in the early pathogenesis of atherosclerosis.

Methods

The 15-oxo-ETE level in serum was detected by means of liquid chromatography and online tandem mass spectrometry (LC-MS/MS). And the underlying mechanisms were illuminated by molecular techniques, including immunoblotting, MTT assay, immunocytochemistry and Immunohistochemistry.

Results

Increased 15-oxo-ETE level is found in in patients with acute myocardial infarction (AMI). After 15-oxo-ETE treatment, Human umbilical vein endothelial cells (HUVECs) showed more attractive to monocytes, whereas monocyte adhesion is suppressed when treated with PKC inhibitor. In ex vivo study, exposure of arteries from C57 mice and ApoE−/−mice to 15-oxo-ETE led to significantly increased E-selectin expression and monocyte adhesion.

Conclusions

This is the first report that 15-oxo-ETE promotes early pathological process of atherosclerosis by accelerating E-selectin expression and monocyte adhesion. 15-oxo-ETE -induced monocyte adhesion is partly attributable to activation of PKC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0518-2) contains supplementary material, which is available to authorized users.

Trimethylamine N-oxide in atherogenesis: impairing endothelial self-repair capacity and enhancing monocyte adhesion

Several studies have reported a strong association between high plasma level of trimethylamine N-oxide (TMAO) and atherosclerosis development. However, the exact mechanism underlying this correlation is unknown. In the present study, we try to explore the impact of TMAO on endothelial dysfunction. After TMAO treatment, human umbilical vein endothelial cells (HUVECs) showed significant impairment in cellular proliferation and HUVECs-extracellular matrix (ECM) adhesion compared with control. Likewise, TMAO markedly suppressed HUVECs migration in transwell migration assay and wound healing assay. In addition, we found TMAO up-regulated vascular cell adhesion molecule-1 (VCAM-1) expression, promoted monocyte adherence, activated protein kinase C (PKC) and p-NF-κB. Interestingly, TMAO-stimulated VCAM-1 expression and monocyte adherence were diminished by PKC inhibitor. These results demonstrate that TMAO promotes early pathological process of atherosclerosis by accelerating endothelial dysfunction, including decreasing endothelial self-repair and increasing monocyte adhesion. Furthermore, TMAO-induced monocyte adhesion is partly attributable to activation of PKC/NF-κB/VCAM-1.