Diabetes and high-glucose could upregulate the expression of receptor for activated C kinase 1 in retina

BACKGROUND Diabetic retinopathy(DR)is a major ocular complication of diabetes mellitus,leading to visual impairment.Retinal pigment epithelium(RPE)injury is a key component of the outer blood retinal barrier,and its damage is an important indicator of DR.Receptor for activated C kinase 1(RACK1)activates protein kinase C-ε(PKC-ε)to promote the generation of reactive oxygen species(ROS)in RPE cells,leading to apoptosis.Therefore,we hypothesize that the activation of RACK1 under hypoxic/high-glucose conditions may promote RPE cell apoptosis by modulating PKC-ε/ROS,thereby disrupting the barrier effect of the outer blood retinal barrier and contributing to the progression of DR.AIM To investigate the role and associated underlying mechanisms of RACK1 in the development of early DR.METHODS In this study,Sprague-Dawley rats and adult RPE cell line-19(ARPE-19)cells were used as in vivo and in vitro models,respectively,to explore the role of RACK1 in mediating PKC-εin early DR.Furthermore,the impact of RACK1 on apoptosis and barrier function of RPE cells was also investigated in the former model.RESULTS Streptozotocin-induced diabetic rats showed increased apoptosis and upregulated expression of RACK1 and PKC-εproteins in RPE cells following a prolonged modeling.Similarly,ARPE-19 cells exposed to high glucose and hypoxia displayed elevated mRNA and protein levels of RACK1 and PKC-ε,accompanied by an increases in ROS production,apoptosis rate,and monolayer permeability.However,silencing RACK1 significantly downregulated the expression of PKC-εand ROS,reduced cell apoptosis and permeability,and protected barrier function.CONCLUSION RACK1 plays a significant role in the development of early DR and might serve as a potential therapeutic target for DR by regulating RPE apoptosis and barrier function.

Metformin promotes angiogenesis and functional recovery in aged mice after spinal cord injury by adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway

Treatment with metformin can lead to the recovery of pleiotropic biological activities after spinal cord injury.However,its effect on spinal cord injury in aged mice remains unclear.Considering the essential role of angiogenesis during the regeneration process,we hypothesized that metformin activates the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway in endothelial cells,thereby promoting microvascular regeneration in aged mice after spinal cord injury.In this study,we established young and aged mouse models of contusive spinal cord injury using a modified Allen method.We found that aging hindered the recovery of neurological function and the formation of blood vessels in the spinal cord.Treatment with metformin promoted spinal cord microvascular endothelial cell migration and blood vessel formation in vitro.Furthermore,intraperitoneal injection of metformin in an in vivo model promoted endothelial cell proliferation and increased the density of new blood vessels in the spinal cord,thereby improving neurological function.The role of metformin was reversed by compound C,an adenosine monophosphate-activated protein kinase inhibitor,both in vivo and in vitro,suggesting that the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway likely regulates metformin-mediated angiogenesis after spinal cord injury.These findings suggest that metformin promotes vascular regeneration in the injured spinal cord by activating the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway,thereby improving the neurological function of aged mice after spinal cord injury.

Critical Role of Protein Kinase C (PKC) in the Onset of Airway Hypersensitivity in Ova-Sensitized Guinea Pig Model of Asthma

Background and Objectives: Protein kinase C (PKC) activation plays an important role in activation of T-lymphocytes in asthma. Airway hypersensitivity is one of the main characteristic features of asthma, the mechanism of onset of which is not clearly understood. Therefore, the objective was to elucidate the role of PKC in etiopathogenesis of airway hypersensitivity in asthma. Methods: Male guinea pigs (n = 30) were sensitized with ovalbumin and day of initial allergen-specific immune response determined by intradermal test, airway hypersensitivity, BALF cytology and lung histopathology. Total PKC activity, PKC isoenzymes and phosphoinositides were assessed in airway smooth muscles (ASM) and peripheral blood lymphocytes. Results: Intradermal test revealed that day 9 was the earliest time of allergen-specific response and onset of airway hypersensitivity to ovalbumin. It was associated with significant increase in total and differential (lymphocytes and eosinophils) BALF counts and grade I peribronchiolar chronic lymphocytic inflammation in lung. On day 14, grade II infiltration of lymphocytes and eosinophils with onset ofstructural remodelingofproximal and distal airways was seen. Total PKC activity, expression of PKCα, PKCε and phosphoinositides increased significantly in ASM and lymphocytes on day 9 and were maximum on day 14. There was no change in PKC-τ expression. Conclusions: Activation of PKC, particularly PKCα and PKCε, mediated signal transduction pathway plays a critical role in lymphocyte infiltration and onset of airway hypersensitivity, airway remodeling and asthma pathophysiology. The present study is the first one on the mechanism of the etiopathogenesis of the disease, which shows a direct evidence of the role of PKC mediated pathway in the initiation and onset of airway hypersensitivity in ovalbumin sensitized guinea pig model.

Latest progress in the research of protein kinase C(PKC)isoform-specific signaling and PKC-modulated autophagy in ischemic stroke

Ischemic stroke is a major cause of morbidity and mortality,and currently there is no effective treatment.The family of protein kinase C(PKCs)could phosphorylate serine or threonine residues of its substrate proteins and play a key role in the ischemia/reperfusion injury.Autophagy is essential for maintaining cell homeostasis under physiological condition and acts as a double-edged sword in the process of ischemic neuronal death.In this article,we reviewed the PKCs isoform-specific signaling pathways and PKC-modulated autophagy in ischemic stroke.

The Effects of Protein Kinase C (PKC) on the Tension of Normal and Passively Sensitized Human Airway Smooth Muscle and the Activity of Voltage-dependent Delayed Rectifier Potassium Channel (Kv)

The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （HASM）, by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential （Em） were also detected. The results showed that phorbol 12-myristate 13-acetate （PMA）, a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group （P〈0.05）, and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO （a PMA menstruum）-treated group （P〈0.01）. This effect could be blocked by Ro31-8220 （P〈0.01 ）. It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.

基于PGE2/PKC/TRPV1信号通路研究热敏灸对膝骨性关节炎兔镇痛效应机制

目的观察热敏灸对膝骨性关节炎(KOA)兔血清PGE2、背根神经节PKC、穴区皮肤TRPV1的影响,探讨其治疗KOA的作用机制。方法36只雄性普通级新西兰兔随机分为空白组(6只)、假手术组(6只)、造模组(24只)。采用木瓜蛋白酶溶液注射膝关节腔法造模15d,假手术组关节腔内注射等量的0.9%NaCl溶液。造模成功后,造模组随机分成模型组(6只),艾灸组(18只),艾灸组艾灸“犊鼻”穴,每日1次,每次40 min,共7 d,根据兔艾灸过程中温度变化分为热敏灸组(10只)和非热敏灸组(7只),空白组、假手术组、模型组不予干预措施。干预结束后,肉眼、光镜下观察膝关节滑膜形态学变化;ELISA法检测血清PGE2表达;Real-time PCR法检测各组兔背根神经节PKC mRNA、穴区皮肤TRPV1 mRNA的含量。结果(1)干预后模型组兔膝关节腔内有大量积液,滑膜增生肥厚,伴有血管增生及大量炎症细胞成团聚集;热敏灸及非热敏灸组关节腔内积液减少,滑膜异常增生改善。(2)与空白组比较,模型组血清PGE2含量明显上升(P<0.01);与模型组比较,热敏灸组、非热敏灸组血清PGE2含量下降,差异有统计学意义(均P<0.01);与非热敏灸组比较,热敏灸组血清PGE2含量下降,差异有统计学意义(P<0.05)。(3)与空白组比较,模型组背根神经节PKC mRNA、穴区皮肤TRPV1 mRNA含量升高,差异有统计学意义(均P<0.01);与模型组比较,热敏灸及非热敏灸组PKC、TRPV1 mRNA表达下降,差异有统计学意义(均P<0.01);与非热敏灸组比较,热敏灸组PKC、TRPV1 mRNA表达下降,差异有统计学意义(P<0.05)。结论热敏灸可抑制PGE2、PKC、TRPV1的高表达,从而抑制痛觉过敏,减轻KOA滑膜炎性反应,缓解关节损害,这可能是热敏灸治疗KOA的效应机制之一。

TRPA1通过PLC/PKC信号通路对偏头痛大鼠的行为学和疼痛敏感性的影响

目的 探讨瞬时受体电位锚蛋白1(TRPA1)通过磷酯酶C(PLC)/蛋白激酶C(PKC)信号通路对偏头痛大鼠的行为学和疼痛敏感性的影响。方法 将SD大鼠随机分为对照组、模型组、TRPA1敲低组(腺病毒包装的TRPA1 siRNA载体)、TRPA1空载组(空慢病毒载体)、TRPA1敲低+PMA(PKC激活剂)组,每组12只,分组以腺病毒包装的TRPA1 siRNA载体、空慢病毒载体及PMA干预处理24 h后,模型组与给药干预组皮下注射10 mg/kg硝酸甘油以制备偏头痛大鼠模型,对照大鼠组皮下注射等剂量0.9%氯化钠溶液,然后以qRT-PCR实验检测除TRPA1敲低+PMA组外其余5组大鼠脑组织及血液中TRPA1 mRNA的表达;观察5组大鼠行为,记录其耳红消失时间及一段时间内挠头次数、爬笼次数;检测5组大鼠机械性疼痛及温度痛阈;酶标仪检测5组大鼠血清促炎因子前列腺素E2(PGE2)、白介素(IL)-6及抗炎因子IL-10水平;免疫印迹实验检测5组大鼠脑组织PLC/PKC通路相关蛋白表达。结果 与对照组比较,模型组、TRPA1空载组大鼠缩头阈值、热刺激潜伏期、血清IL-10水平显著降低(P<0.05),脑组织及外周血中TRPA1表达、耳红消失时间、挠头次数、爬笼次数、动态痛觉超敏评分、血清PGE2、IL-6水平、脑组织PLC/PKC通路蛋白p-PLC/PLC、p-PKC/PKC显著升高(P<0.05)。与模型组比较,TRPA1敲低组大鼠缩头阈值、热刺激潜伏期、血清IL-10水平升高(P<0.05),脑组织及外周血中TRPA1表达、耳红消失时间、挠头次数、爬笼次数、动态痛觉超敏评分、血清PGE2、IL-6水平、脑组织PLC/PKC通路蛋白p-PLC/PLC、p-PKC/PKC降低(P<0.05);TRPA1空载组大鼠各指标无显著变化(P>0.05)。与TRPA1敲低组比较,TRPA1敲低+PMA组大鼠缩头阈值、热刺激潜伏期、血清IL-10水平降低(P<0.05),耳红消失时间、挠头次数、爬笼次数、动态痛觉超敏评分、血清PGE2、IL-6水平、脑组织PLC/PKC通路蛋白p-PKC/PKC升高(P<0.05)。结论 TRPA1可通过调控PLC/PKC信号通路介导大鼠偏头痛的发生,下调TRPA1表达可通过抑制PLC/PKC信号通路激活减轻炎症,以降低大鼠疼痛敏感性,最终改善头疼症状。

依达拉奉右莰醇通过PKC/ERK通路对脑缺血再灌注大鼠发挥脑保护作用

[目的]观察依达拉奉右莰醇(EDDE)对脑缺血再灌注大鼠神经元凋亡的影响,并探讨其作用机制。[方法]将SD大鼠随机分为假手术组、大脑中动脉闭塞(MCAO)组、低剂量EDDE组(EDDE-L组,3 mg/kg)、高剂量EDDE组(EDDE-H组,6 mg/kg)、白屈菜红碱(CHE,PKC抑制剂)组(5 mg/kg CHE)、EDDE+CHE组(6 mg/kg EDDE+5 mg/kg CHE),每组15只。除假手术组外,其余各组大鼠采用线栓法构建MCAO模型。对各组大鼠进行神经功能缺损评分;再灌注24 h后,TTC染色检测大鼠脑梗死体积;HE染色观察皮质神经细胞病理损伤;TUNEL染色检测皮质神经细胞凋亡;免疫组织化学法检测皮质区神经细胞Bcl-2、Bax的表达;Western blot检测脑组织Caspase-3、cleaved Caspase-3和蛋白激酶C(PKC)/细胞外信号调节激酶(ERK)通路相关蛋白(PKC、p-PKC、ERK1/2、p-ERK1/2)的表达。[结果]与假手术组相比,MCAO组大鼠神经功能缺损评分、脑梗死体积百分比和神经细胞凋亡率升高,Bax阳性表达增加,cleaved Caspase-3/Caspase-3比值升高(均P<0.05),Bcl-2阳性表达和Bcl-2/Bax比值降低,脑组织p-PKC/PKC、p-ERK1/2/ERK1/2比值降低(均P<0.05),脑皮质细胞排列稀疏,神经细胞肿胀、空泡样变性明显、核固缩,组织坏死;与MCAO组相比,EDDE-L组和EDDE-H组大鼠神经功能缺损评分、脑梗死体积百分比和神经细胞凋亡率降低,Bax阳性表达减少,cleaved Caspase-3/Caspase-3比值降低(均P<0.05),Bcl-2阳性表达升高,Bcl-2/Bax、p-PKC/PKC和p-ERK1/2/ERK1/2比值升高(均P<0.05),脑皮质病理损伤有不同程度的改善,神经细胞数量增多,空泡样变性减轻,胞核较清晰,且EDDE-H组的改善优于EDDE-L组;CHE可以消除EDDE的神经保护作用。[结论]EDDE可抑制神经细胞凋亡,减轻脑缺血再灌注损伤,其机制可能与激活PKC/ERK通路有关。

Calycosin improves cognitive function in a transgenic mouse model of Alzheimer's disease by activating the protein kinase C pathway

The major pathological changes in Alzheimer＇s disease are beta amyloid deposits and cognitive impairment. Calycosin is a typical phy- toestrogen derived from radix astragali that binds to estrogen receptors to produce estrogen-like effects. Radix astragali Calycosin has been shown to relieve cognitive impairment induced by diabetes mellitus, suggesting calycosin may improve the cognitive function of Alzhei- mer＇s disease patients. The protein kinase C pathway is upstream of the mitogen-activated protein kinase pathway and exerts a neuropro- tective effect by regulating Alzheimer＇s disease-related beta amyloid degradation. We hypothesized that calycosin improves the cognitive function of a transgenic mouse model of Alzheimer＇s disease by activating the protein kinase C pathway. Various doses of calycosin （10, 20 and 40 mg/kg） were intraperitoneally injected into APP/PS1 transgenic mice that model Alzheimer＇s disease. Calycosin diminished hippocampal beta amyloid, Tau protein, interleukin-lbeta, tumor necrosis factor-alpha, acetylcholinesterase and malondialdehyde levels in a dose-dependent manner, and increased acetylcholine and glutathione activities. The administration of a protein kinase C inhibitor, cal- phostin C, abolished the neuroprotective effects of calycosin including improving cognitive ability, and anti-oxidative and anti-inflammato- ry effects. Our data demonstrated that calycosin mitigated oxidative stress and inflammatory responses in the hippocampus of Alzheimer＇s disease model mice by activating the protein kinase C pathway, and thereby improving cognitive function.

Effect of gastrin on protein kinase C and its subtype in human colon cancer cell line SW480

INTRODUCTIONGastrin is atrophic gastrointestinal hormone whichis secreted by G cell.Gastrin has long beenconsidered a growth stimulatory hormone formucosa of the gastrointestinal tract.The growthresponses of certain colorectal cancer cells,andxenografts,can be stimulated by endogenousgastrin.Protein kinase C (PKC) is a family ofisozymes that plays a crucial role in transducingsignals of many hormones,growth peptides,

Cell metabolism pathways involved in the pathophysiological changes of diabetic peripheral neuropathy

Diabetic peripheral neuropathy is a common complication of diabetes mellitus.Elucidating the pathophysiological metabolic mechanism impels the generation of ideal therapies.However,existing limited treatments for diabetic peripheral neuropathy expose the urgent need for cell metabolism research.Given the lack of comprehensive understanding of energy metabolism changes and related signaling pathways in diabetic peripheral neuropathy,it is essential to explore energy changes and metabolic changes in diabetic peripheral neuropathy to develop suitable treatment methods.This review summarizes the pathophysiological mechanism of diabetic peripheral neuropathy from the perspective of cellular metabolism and the specific interventions for different metabolic pathways to develop effective treatment methods.Various metabolic mechanisms(e.g.,polyol,hexosamine,protein kinase C pathway)are associated with diabetic peripheral neuropathy,and researchers are looking for more effective treatments through these pathways.

Relationship between Invasiveness of Pituitary Somatotrophinomas and Structural Abnormalities of Protein Kinase C Gene in Human

The potential role of the protein kinase C (PKC) transduction systemin controlling proliferation of human pituitary somatotrophinomas was investigat-ed. Twenty somatotrophinomas were studied using PCR and diract sequencing methods. No point mutation within the QPKC gene, previously thought to be as-sociated with invasive pituitary tumors, was found in any of the 20 somatotrophi-nomas. It is concluded that PKC trareduction system may play an important rolein controlling pituitary somatotrophinoma proliferation, but there is no correlation between invasiveness and the previously reported QPKC gene mutation.

Fungus induces the release of IL- 8 in human corneal epithelial cells, via Dectin-1-mediated protein kinase C pathways

AIM: To identify whether Aspergillus fumigatus(A.fumigatus) hyphae antigens induced the release of interleukin-8(IL-8) in anti-fungal innate immunity of cultured human corneal epithelial cells(HCECs) and determine the involvement of intracellular signalling pathways. METHODS: HCECs were treated with A. fumigatus hyphae antigens with different concentrations and time.The cytoplasmic calcium of HCECs were assessed by fluorescence imaging. Western blot was used to detect the expression of Ca2 +-dependent protein kinase C(PKC). The IL-8 levels were determined by specific human IL-8 enzyme-linked immunosorbent assay(ELISA) and reverse transcriptase polymerase chain reaction(RT-PCR). Using a series of pharmacological inhibitors, we examined the upstream signalling pathway responsible for IL-8 expression in response to A.fumigatus hyphae antigens. RESULTS: Cells exposed to A. fumigatus hyphae antigens showed higher level of IL-8 m RNA expression and protein production. We demonstrated here that stimulation of HCECs with A. fumigatus hyphae triggers an intracellular Ca2 +flux and results in the activation of Ca2 +-dependent PKC(α, βⅠ and βⅡ) which can be attenuated by pre-treatment of cells with laminarin,suggesting that Dectin-1 signals pathway induced cytoplasmic calcium and influence the activation of PKC in HCECs. Inhibitors of Ca2 +-dependent PKC(Ro-31-8220 and Go6976) significantly abolished hyphae-induced expression of IL-8.CONCLUSION: Our findings suggest that A. fumigatushyphae-induced IL-8 expression was regulated by the activation of Dectin-1-mediated Ca2 +-dependent PKC in HCECs.

Effects of cell membrane phospholipid level and protein kinase C isoenzyme expression on hepatic metastasis of colorectal carcinoma

BACKGROUND: The molecular mechanism of hepaticmetastasis of colorectal cancer is not well understood. Theaim of this study was to assess the relations between phos-pholipid contents of cellular membrane and isoenzyme ex-pression of protein kinase C (PKC) and their effects on he-patic metastasis of colorectal cancer.METHODS: High performance liquid chromatography wasused to detect contents of cell membrane phospholipids:phosphatidylinosital (PI), phosphatidylserine (PS), phos-phatidylethanolamine (PE) and phosphatidylcholine (PC)in primary foci, paratumor mucosa and hepatic metastaticfoci in patients with colorectal carcinoma. The mRNA ex-pression levels of PKC-α, -δ, -ε, -λ, -ξ isoenzymeswere detected with the QRT-PCR technique.RESULTS: The levels of PI, PC and PE in primary foci andhepatic metastatic foci were higher than those in paratumormucosa. The level of PE in hepatic metastatic foci wasmuch higher than that in primary foci (t =98.88, P <0.01);but the levels of PI and PC were not significantly differentbetween primary foci and hepatic metastatic foci (t =1.73 ,1.36, P>0.05). The expression levels of -δ, -ε,-λ, -ξ were enhanced in primary foci and hepatic metasta-tic foci, but the level of PKC-α in primary foci was de-creased as compared with that in paratumor mucosa. Thelevels of PKC-δ, -ε, -λ, -ξ in hepatic metastatic foci werehigher than those in primary foci. A positive correlationwas observed between the expression levels of PI, PC andand also between those of PE and PKC-δ, -ε, -λ,-ξ. However, there was a close negative correlation be-tween PE and PKC-α.CONCLUSION: Increased levels of PI and PC and de-creased ratio of PKC-α to are related to colorectalcancer genesis. Increased levels of PE, increased expressionof PKC-δ, -ε, -λ, -ξ isoenzymes and decreased level ofPKC-α are related to hepatic metastasis in colorectal carci-noma.

GHRP-6 Induces CREB Phosphorylation and Growth Hormone Secretion via a Protein Kinase Cσ-dependent Pathway in GH3 Cells

This study examined the effect of GHRP-6, a known GHSs receptor agonist, on the phosphorylation of cAMP-responsive element-binding protein （CREB） and the tmderly mechanism. GH3 cells were cultured and subjected to different treatments as follows： GHRP-6, GHRP-6 plus GHRH, phorbol ester （PMA）, an activator of PKC, alone or in combination with GHRP-6, G66983, a general inhibitor of PKCs, in the presence or absence of GHRP-6, rottlerin, an inhibitor of PKCs, alone or plus GHRP-6. The cells were transiently transfected with PKCσ-specific siRNA and then treated with GHRP-6. GH level was measured by enzyme-linked immunosorbent assay （ELISA）. The expression of phosphor-CREB, PKCσ, PKC0 and phosphor-PKCo was determined by Western blotting. The results showed that GHRP-6 stimulated GH secretion in both time- and dose-dependent manners and enhanced the effect of GHRH on GH secretion. GHRP-6 was also found to induce CREB phosphorylation. Moreover, GH secretion was enhanced by the PKC activator PMA and reduced by the PKC inhibitors （G66983, rottlerin） and knockdown of PKCσ. PKCσ could be activated by GHRP-6. It is concluded that PKC, especialiy PKCσ, mediates CREB phosphorylation and GHRP-6-induced GH secretion.

Hepatic injury in rats with obstructive jaundice: roles of the protein kinase C signal pathway and cytoprotection of fructose

BACKGROUND: Fructose is cytoprotective during bile salt-induced apoptosis of hepatocytes by regulating protein kinase C (PKC). This study was undertaken to explore the regulating mechanism of hepatic injury in rats with obstructive jaundice, and to detect the PKC signal pathway. METHODS: Rat hepatocytes were isolated by in situ colla-genase perfusion and primary culture, and pretreated with various concentrations of PKC agonist phorbol myristate acetale (PMA) and inhibitor chelerythrine for 20 minutes. After pretreatment, 50 μmol/L glycochenodeoxycholate (GCDC) was added for additional 24 hours. Subsequently, the cells were detected by FCM and TUNEL. After adding with different concentrations of fructose and 100 μmol GCDC , the hepatocytes were evaluated by FCM and TUNEL. Experimental obstructive jaundice was induced with fructose and without fructose via double ligation of the bile duct for 3, 7, 14, and 21 days. Apoptotic status in the liver of all rats was detected with TUNEL, and PKC protein in the liver of obstructive jaundice ( OJ) with the immunohisto-chemistry method. RESULTS: PMA increased GCDC-induced apoptosis and chelerythrine decreased GCDC-induced apoptosis in a concentration-dependent manner. Adding with different concentration of fructose and 100 μmol GCDC, the decreased apoptotic rate was related to the concentration of fructose. The apoptotic rate of the liver was related to times of OJ. PKC and apoptosis index (AI) were the highest after a 14-day ligation of the bile duct without use of fructose. AI and PKC were decreasing from a 14-day ligation of the bile duct with fructose. CONCLUSIONS: PKC takes part in the regulation, occurrence , and progression of hepatic injury in OJ. Fructose is cytoprotective during bile salt-induced apoptosis of hepato-cytes by regulating PKC.

Effects of Mitochondrial ATP-sensitive K^+ Channel on Protein Kinase C Pathway and Airway Smooth Muscle Cell Proliferation in Asthma

The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.

Characterization and Expression Analysis of Protein Kinase C Gene from Dunaliella salina

Protein kinase C (PKC) has a crucial role in signal transduction for a variety of biologically active substances which activate cellular functions and proliferation. We previously isolated the full-length PKC gene from Dunaliella salina (DsPKC) using rapid amplification of cDNA ends (RACE) and RT-PCR methods. And we submitted the mRNA sequence of DsPKC gene to NCBI (Genbank No. JN625213). In the present paper, the DsPKC gene open reading frame obtained by PCR was cloned into pGS-21a vector and transformed into Escherichia coli to generate the fusion protein. Bioinformatics analysis revealed that DsPKC gene was a member of serine/threonine kinase with two conserved domains and highly conserved motifs. The DsPKC was highly expressed upon induction with isopropyl-β-d-thiogalactoside (IPTG) at a final concentration of 0.2 mmol L 1 at 37℃. Under salt stress, the fu- sion protein Green Fluorescent Protein (GFP)-DsPKC was transferred from the cytoplasm to the cell membrane. The expression pat- tern of DsPKC gene was analyzed using real-time quantitative PCR, and indicated that DsPKC gene was up-regulated by 3.0 mol L 1 NaCl at 12 h, which was significantly higher than in control values (P < 0.05). These results suggest that the DsPKC gene plays an important role in response to salt stress in D. salina.

Breviscapine alleviates hepatic injury and inhibits PKC-mRNA and its protein expression in brain-dead BA-Ma mini pigs

BACKGROUND: Brain-dead donors are the main sources for organ transplantation, but many studies show that brain-death affects the organ's function after transplantation. This study was undertaken to investigate liver injury after brain-death in BA-Ma mini pigs and the protective effects of breviscapine on hepatic function and on PKC-alpha mRNA and its protein expression. METHODS: Fifteen BA-Ma mini pigs were equally divided into 3 groups at random: brain-dead (group B), breviscapine pretreated (group P), and control (group Q. The brain-dead model was established by increasing intracranial pressure in a modified, slow and intermittent way. At 3, 6, 12, 18 and 24 hours after the initial brain-death, the levels of serum AST, ALT, TNF-alpha, IL-1 beta, and IL-6 were determined. The changes in hepatic tissues were assessed, and the expression of PKC-alpha and PKC-alpha mRNA was detected by immunohistochemistry and RTPCR, respectively. RESULTS: The levels of AST and ALT in groups B and P began to increase 12 hours after brain-death, while the values in group P were lower than those in group B (P<0.05). The levels of IL-1 beta, IL-6, and TNF-alpha in groups B and P at 3, 6, 12 and 18 hours were lower than those in group B (P<0.05). At 6, 12 and 24 hours, the expressions of PKC-a mRNA and PKC-a protein in group P were lower than those in group B (P<0.05). The degree of injury to hepatic cells in group P was milder than that in group B. CONCLUSIONS: Breviscapine inhibits the degree of PKC-alpha mRNA transcription and its protein translation, decreases the release of inflammatory factors, and thus alleviates hepatic injury during brain-death.

Effects of Puerarin on Pulmonary Vascular Remodeling and Protein Kinase C-α in Chronic Cigarette Smoke Exposure Smoke-exposed Rats

In order to investigate the effects of puerarin on pulmonary vascular remodeling and protein kinase C-α （PKC-α） in chronic exposure smoke rats, 54 male Wistar rats were randomly divided into 7 groups： control group （C group）, smoke exposure groups （S4w group, S8w group）, puerarin groups （P4w group, P8w group）, propylene glycol control groups （PC4w group, PC8w 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 （α-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-α mRNA and protein expression in pulmonary arteries. The results showed that in cigarette smoke-exposed rats the percentage of CMA/IAPA and α-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-α 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-α 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.