Effects of sevoflurane on tight junction protein expression and PKC-alpha translocation after pulmonary ischemia-reperfusion injury

Pulmonary dysfunction caused by ischemia-reperfusion injury is the leading cause of mortality in lung transplantation. We aimed to investigate the effects of sevoflurane pretreatment on lung permeability, tight junction protein occludin and zona occludens 1 (ZO-1) expression, and translocation of protein kinase C (PKC)-alpha after ischemia-reperfusion. A lung ischemia-reperfusion injury model was established in 96 male Wistar rats following the modified Eppinger method. The rats were divided into four groups with 24 rats in each group: a control (group C), an ischemia-reperfusion group (IR group), a sevoflurane control group (sev-C group), and a sevoflurane ischemia-reperfusion group (sev-IR group). There were three time points in each group: ischemic occlusion for 45 min, reperfusion for 60 min and reperfusion for 120 min; and there were six rats per time point. For the 120-min reperfusion group, six extra rats underwent bronchoalveolar lavage. Mean arterial pressure (MAP) and pulse oxygen saturation (SpO2) were recorded at each time point. The wet/dry weight ratio and lung permeability index (LPI) were measured. Quantitative RT-PCR and Western blot were used to measure pulmonary occludin and ZO-1, and Western blot was used to measure cytosolic and membranous PKC-alpha in the lung. Lung permeability was significantly increased after ischemia-reperfusion. Sevoflurane pretreatment promoted pulmonary expression of occludin and ZO-1 after reperfusion and inhibited the translocation of PKC-alpha. In conclusion, sevoflurane pretreatment alleviated lung permeability by upregulating occludin and ZO-1 after ischemia-reperfusion. Sevoflurane pretreatment inhibited the translocation and activation of PKC-alpha, which also contributed to the lung-protective effect of sevoflurane.

Preeclampsia serum-induced collagen I expression and intracellular calcium levels in arterial smooth muscle cells are mediated by the PLC-gamma1 pathway

In women with preeclampsia (PE), endothelial cell (EC) dysfunction can lead to altered secretion of paracrine factors that induce peripheral vasoconstriction and proteinuria. This study examined the hypothesis that PE sera may directly or indirectly, through human umbilical vein ECs (HUVECs), stimulate phospholipase C-gamma1-1,4,5-trisphosphate (PLC-gamma1-IP3) signaling, thereby increasing protein kinase C-alpha (PKC-alpha) activity, collagen I expression and intracellular Ca2+ concentrations ([Ca2+]i) in human umbilical artery smooth muscle cells (HUASMCs). HUASMCs and HUVECs were cocultured with normal or PE sera before PLC-gamma1 silencing. Increased PLC-gamma1 and IP3 receptor (IP3R) phosphorylation was observed in cocultured HUASMCs stimulated with PE sera (P<0.05). In addition, PE serum significantly increased HUASMC viability and reduced their apoptosis (P<0.05); these effects were abrogated with PLC-gamma1 silencing. Compared with normal sera, PE sera increased [Ca2+]i in cocultured HUASMCs (P<0.05), which was inhibited by PLC-gamma1 and IP3R silencing. Finally, PE sera-induced PKC-alpha activity and collagen I expression was inhibited by PLC-gamma1 small interfering RNA (siRNA) (P<0.05). These results suggest that vasoactive substances in the PE serum may induce deposition in the extracellular matrix through the activation of PLC-gamma1, which may in turn result in thickening and hardening of the placental vascular wall, placental blood supply shortage, fetal hypoxia-ischemia and intrauterine growth retardation or intrauterine fetal death. PE sera increased [Ca2+]i and induced PKC-alpha activation and collagen I expression in cocultured HUASMCs via the PLC-gamma1 pathway.

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.

Effects of puerarin on pulmonary vascular remodeling and protein kinase C-alpha in chronic cigarette smoke exposure smoke-exposed rats / 华中科技大学学报（医学）（英德文版）

In order to investigate the effects of puerarin on pulmonary vascular remodeling and protein kinase C-alpha (PKC-alpha) in chronic exposure smoke rats, 54 male Wistar rats were randomly divided into 7 groups: control group (C group), smoke exposure groups (S(4w) group, S(8w) group), puerarin groups (P(4w) group, P(8w) group), propylene glycol control groups (PC(4w) group, PC(8w) group). Rats were exposed to cigarette smoke or air for 4 to 8 weeks. Rats in puerarin groups also received puerarin. To evaluate vascular remodeling, alpha-smooth muscle actin (alpha-SM-actin) staining was used to count the percentage of completely muscularised vessels to intraacinar pulmonary arteries (CMA/IAPA) which was determined by morphometric analysis of histological sections. Pulmonary artery smooth muscle cell (PASMC) apoptosis was detected by in situ end labeling technique (TUNEL), and proliferation by proliferating cell nuclear antigen (PCNA) staining. Reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence staining and Western blot analysis were done to detect the PKC-alpha mRNA and protein expression in pulmonary arteries. The results showed that in cigarette smoke-exposed rats the percentage of CMA/IAPA and alpha-SM-actin expression were increased greatly, PASMC apoptosis was increased and proliferation was markedly increased; Apoptosis indices (AI) and proliferation indices (PI) were higher than in C group; AI and PI were correlated with vascular remodeling indices; The expression of PKC-alpha mRNA and protein in pulmonary arteries was significantly higher than in C group. In rats treated with puerarin, the percentage of CMA/IAPA and cell proliferation was reduced, whereas PASMC apoptosis was increased; The expression levels of PKC-alpha mRNA and protein were lower than in smoke exposure rats. There was no difference among all these data between S groups and PC groups. These findings suggested that cigarette smoke-induced pulmonary vascular remodeling was most likely an effect of the imbalance of PASMC proliferation and apoptosis. Puerarin appears to be able to reduce cell proliferation and vascular remodeling possibly through PKC signaling transduction pathway.

Endothelin 1 protects HN33 cells from serum deprivation-induced neuronal apoptosis through Ca2+-PKCalpha-ERK pathway

Endothelins (ETs), which were originally found to be potent vasoactive transmitters, were known to be implicated in nervous system, but the mode of mechanism remains unclear. ETs (ET-1, ET-2, and ET-3) were added to HN33 (mouse hippocampal neuron chi neuroblastoma) cells. Among the three types of ET, only ET-1 increased the intracellular calcium levels in a PLC dependent manner with the induction of ERK 1/2 activation. As the result of ET-1 exposure, the survival rate of HN33 cells and the PKCalpha translocation into the plasma membrane were increased. We suggest that ET-1 participated in the neuroprotective effect involving the calcium-PKCalpha-ERK1/2 pathway.

A Study on Altered Expression of Serine Palmitoyltransferase and Ceramidase in Psoriatic Skin Lesion

Ceramides are the main lipid component maintaining the lamellae structure of stratum corneum, as well as lipid second messengers for the regulation of cellular proliferation and/or apoptosis. In our previous study, psoriatic skin lesions showed marked decreased levels of ceramides and signaling molecules, specially protein kinase C-alpha (PKC-alpha) and c-jun N-terminal kinase (JNK) in proportion to the psoriasis area and severity index (PASI) scores, which suggested that the depletion of ceramide is responsible for epidermal hyperproliferation of psoriasis via downregulation of proapoptotic signal cascade such as PKC-alpha and JNK. In this study, we investigated the protein expression of serine palmitoyltransferase (SPT) and ceramidase, two major ceramide metabolizing enzymes, in both psoriatic epidermis and non-lesional epidermis. The expression of SPT, the ceramide generating enzyme in the de novo synthesis in psoriatic epidermis, was significantly less than that of the non-lesional epidermis, which was inversely correlated with PASI score. However, the expression of ceramidase, the degradative enzyme of ceramides, showed no significant difference between the lesional epidermis and the non-lesional epidermis of psoriatic patients. This might suggest that decreased expression of SPT protein is one of the important causative factors for decreased ceramide levels in psoriasis.

PMA-induced up-regulation of MMP-9 is regulated by a PKCalpha-NF-kappaB cascade in human lung epithelial cells

Expression of matrix metalloproteinase-9 (MMP-9) is associated with airway remodeling and tissue injury in asthma. However, little is known about how MMP-9 is up-regulated in airway epithelial cells. In this study, we show that phorbol myristate acetate (PMA) induces MMP-9 expression via a protein kinase Calpha(PKCalpha)-dependent signaling cascade in BEAS-2B human lung epithelial cells. Pretreatment with either GF109203X, a general PKC inhibitor, or Go6976, a PKCalpha/beta isozyme inhibitor, inhibited PMA-induced activation of the MMP-9 promoter, as did transient transfection with PKCalpha antisense oligonuclotides. PMA activated NF-kappaB by phosphorylating IkappaB in these cells and this was also inhibited by GF109203X and Go6976, suggesting that PKCalpha acts as an upstream regulator of NF-kappaB in PMA-induced MMP-9 induction. Our results indicate that a "PKCalpha-NF-kappaB"-dependent cascade is involved in the signaling leading to PMA-induced MMP-9 expression in the lung epithelium.

Losses of immunoreactive parvalbumin amacrine and immunoreactive alphaprotein kinase C bipolar cells caused by methylmercury chloride intoxication in the retina of the tropical fish Hoplias malabaricus

To quantify the effects of methylmercury (MeHg) on amacrine and on ON-bipolar cells in the retina, experiments were performed in MeHg-exposed groups of adult trahiras (Hoplias malabaricus) at two dose levels (2 and 6 µg/g, ip). The retinas of test and control groups were processed by mouse anti-parvalbumin and rabbit anti-alphaprotein kinase C (alphaPKC) immunocytochemistry. Morphology and soma location in the inner nuclear layer were used to identify immunoreactive parvalbumin (PV-IR) and alphaPKC (alphaPKC-IR) in wholemount preparations. Cell density, topography and isodensity maps were estimated using confocal images. PV-IR was detected in amacrine cells in the inner nuclear layer and in displaced amacrine cells from the ganglion cell layer, and alphaPKC-IR was detected in ON-bipolar cells. The MeHg-treated group (6 µg/g) showed significant reduction of the ON-bipolar alphaPKC-IR cell density (mean density = 1306 ± 393 cells/mm²) compared to control (1886 ± 892 cells/mm²; P < 0.001). The mean densities found for amacrine PV-IR cells in MeHg-treated retinas were 1040 ± 56 cells/mm² (2 µg/g) and 845 ± 82 cells/mm² (6 µg/g), also lower than control (1312 ± 31 cells/mm²; P < 0.05), differently from the data observed in displaced PV-IR amacrine cells. These results show that MeHg changed the PV-IR amacrine cell density in a dose-dependent way, and reduced the density of alphaKC-IR bipolar cells at the dose of 6 µg/g. Further studies are needed to identify the physiological impact of these findings on visual function.

Ceramides and Cell Signaling Molecules in Psoriatic Epidermis: Reduced Levels of Ceramides, PKC-alpha, and JNK

Ceramides are the main lipids in the stratum corneum and are generated during cellular stress and apoptosis by de novo synthesis or by the action of sphingomyelinase. In addition, they are lipid second messengers produced by sphingolipid metabolism and trigger important cell responses, including protein kinase C-alpha (PKC-alpha) activation and the stimulation of signal transduction pathways with apoptosis and stress-activated protein kinases (SAPK), such as c-jun N-terminal kinase (JNK). Thus, ceramides have anti-proliferative and apoptotic effects. This study measured the changes in the levels of epidermal ceramides and ceramide-related apoptotic signaling molecules in psoriasis patients. Samples from lesional and non-lesional epidermis were obtained from psoriasis patients. Total ceramides were fractionated using thin-layer chromatography, and the levels of PKC-alpha and JNK expression were measured using Western blot analysis with specific antibodies. The ceramide level was reduced significantly, and this was associated with the downregulation of apoptotic signaling molecules, such as PKC-alpha and JNK, in the lesional epidermis of psoriasis patients. These results suggest that the decreased level of ceramides downregulates the apoptotic pathway, leading to epidermal proliferation in psoriasis.