Role of PKCα-Nrf2-HO-1 signaling pathway in endotoxic shock-induced acute lung injury in rabbits / 中华麻醉学杂志

Objective To evaluate the role of protein kinase Cα( PKCα)?nuclear factor E2?related factor 2 ( Nrf2)?heme oxygenase?1 ( HO?1) signaling pathway on endotoxic shock?induced acute lung injury ( ALI) in rabbits. Methods Thirty healthy male New Zealand white rabbits, aged 2 months, weighing 2?0-2?5 kg, were randomly divided into 3 groups ( n=10 each) using a random number table: normal control group ( group C);ALI group ( group ALI);PKCα inhibitor chelerythrine group ( group CHE) . In group CHE, chelerythrine 8 mg∕kg ( in 0?5 ml of DMSO) was injected intraperitoneally, and 30 min later, LPS 5 mg∕kg ( in 2 ml of normal saline) was injected via the auricular vein to induce ALI in ALI and CHE groups. The rabbits were then sacrificed at 6 h after injection of LPS or normal saline, and the lungs were removed for examination of the pathological changes which were scored and for determination of wet∕dry lung weight ratio ( W∕D ratio) , and the expression of Nrf2 and HO?1 protein and mRNA. Results Compared with group C, the pathological score and W∕D ratio were significantly increased, and the expression of Nrf2 and HO?1 protein and mRNA was up?regulated in ALI and CHE groups. The pathological score and W∕D ratio were significantly higher, and the expression of Nrf2 and HO?1 protein and mRNA was lower in group CHE than in group ALI. Conclusion The PKCα?Nrf2?HO?1 signaling pathway is one of the endogenous protective mechanisms underlying endotoxic shock?induced ALI in rabbits.

Effect of m-calpain in PKCα-mediated proliferation of pulmonary artery smooth muscle cells by low dose of ouabain.

There is growing evidence that ouabain, a cardiotonic steroid may promote growth of cardiac and vascular myocytes, indicating its novel role in cell growth and proliferation, without appreciable inhibition of the sodium pump. The mechanism(s) by which low dose of ouabain produces pulmonary artery smooth muscle cell proliferation, a prerequisite for right ventricular hypertrophy, is currently unknown. Here, we analyzed the effects of low dose of ouabain (10 nM) on increase in [Ca2+]i, m-calpain and protein kinase C (PKC) activities on pulmonary artery smooth muscle cell proliferation and determined their sequential involvement in this scenario. We treated bovine pulmonary artery smooth muscle cells with a low dose of ouabain (10 nM) and determined [Ca2+]i in the cells by fluorometric assay using fura2-AM, m-calpain activity by fluorometric assay using SLLVY-AMC as the substrate, PKC activity using an assay kit and assay of Na+/K+ATPase activity spectrophotometrically. We purified m-calpain and PKCα by standard chromatographic procedure by HPLC and then studied cleavage of the purified PKCα by m-calpain using Western immunoblot method. Subsequently, we performed cell proliferation assay utilizing the redox dye resazunin. We used selective inhibitors of [Ca2+]i (BAPTA-AM), m-calpain (MDL28170), PKCα (Go6976) and determined their involvement in ouabain (10 nM)-mediated smooth muscle cell proliferation. Our results suggested that treatment of bovine pulmonary artery smooth muscle cells with a low dose of ouabain (10 nM) increased [Ca2+]i and subsequently stimulated m-calpain activity and proteolytically activated PKCα in caveolae (signaling microdomain also known as signalosomes) of the cells. Upon activation, PKCα increased the smooth muscle cell proliferation via Go/G1 to S/G2-M phase transition. Thus, [Ca2+]i-mCalpain-PKCα signaling axis plays a crucial role during low dose of ouabain-mediated pulmonary artery smooth muscle cell proliferation.

Protein kinase C-α expression in kidney of rat with chronic arsenic poisoning / 中国地方病学杂志

ObjectiveTo investigate the expression and relevant function of protein kinase C (PKC)-α in kidney of rat with chronic arsenic poisoning.MethodsTotally 60 healthy SD rats of clean grade were randomly divided by body weight into 3 groups:high-dose arsenic exposure group (10.0 mg/kg),low-dose arsenic exposure group (0.4 mg/kg),and control group.The rats were exposed by drinking arsenic solution which was mixed with distilled water.Rats were weighed every 10 days and dose volume of arsenic solution was adjusted.After continuous exposure for 4 months,blood and urinary arsenic were determined.Rat kidneys were taken and stained by Immunohistochemistry SABC.PKC-o positive cells in the kidney were observed and counted,and its average gray value was analyzed with image analysis software (Biomias).ResultsProximal tubules PKC-α-positive cell count [(3.62 ± 1.90),(10.07 ± 3.22)/field],glomerular PKC-α-positive cell count [(3.62 ± 1.90),(10.07 ± 3.22)/field]in high and low arsenic group of SD rat kidney were lower than those of the control group [(60.00 ± 9.63),(18.57 ± 2.71/field,all P ＜ 0.05]; both urinary arsenic level[(7366.62 ± 1086.50),(1744.31 ± 300.12)μg,/L]and blood arsenic level [(31.59 ± 9.24),(16.58 ± 2.08)μg/L] in high-dose and low-dose groups were higher than those of the control group [(18.97 ± 3.58),(18.97 ± 3.58)μg/L,all P ＜ 0.05] ; the average gray values of SD rat kidney proximal tubule,glomerular PKC-o positive cells in high-dose and low-dose groups( 142.79 ± 11.16,122.15 ±5.91 ) were higher than that of the control group (114.33 ± 6.70,all P ＜ 0.05).ConclusionsArsenic can decrease SD rat kidney PKC-α -positive cells.The regulatory function of PKC-o in inhibiting cell apoptosis of kidney of rats with arsenic poisoning is weakened.