利拉鲁肽通过p38 MAPK通路改善高同型半胱氨酸血症诱导的大鼠海马氧化应激及炎症损伤

目的:探讨胰高血糖素样肽1(GLP-1)类似物利拉鲁肽(Lir)对高同型半胱氨酸血症(Hhcy)大鼠海马损伤的保护作用及其机制。方法:40只SD大鼠随机分为对照(Ctrl)组、模型(Hhcy)组、Lir低剂量(12.5μg·kg~(-1)·h~(-1))组、Lir中剂量(25.0μg·kg~(-1)·h~(-1))组和Lir高剂量(37.5μg·kg~(-1)·h~(-1))组,采用Western blot法检测大鼠海马组织内丝裂原活化蛋白激酶(MAPK)信号通路中p38、JNK和ERK1/2的蛋白表达及活性依赖的磷酸化水平,同时采用Western blot和免疫组织化学法检测内质网应激标志蛋白免疫球蛋白重链结合蛋白(BIP)和C/EBP同源蛋白(CHOP)的表达水平;采用酶标法检测超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性及丙二醛(MDA)含量;酶联免疫吸附法检测炎症因子白细胞介素1β(IL-1β)、白细胞介素6(IL-6)和肿瘤坏死因子α(TNF-α)水平。结果:Hhcy可明显上调p-p38、BIP和CHOP的蛋白表达量,降低SOD和GSH的活性,升高MDA含量及IL-1β、IL-6和TNF-α水平;腹腔注射Lir可浓度依赖性地改善Hhcy引起的上述内质网应激和炎症反应,并伴有p38 MAPK通路的抑制。结论:Lir可改善Hhcy诱导的大鼠海马组织氧化应激和炎症损伤,其机制可能与抑制p38 MAPK信号通路的过度激活有关。     

Ethanol-induced oxidative stress is mediated by p38 MAPK pathway in mouse hippocampal cells

It has been known that ethanol causes neuronal cell death through oxidative stress. Ethanol itself and reactive oxygen species (ROS) produced by ethanol modulate intracellular signaling pathways including mitogen-activated protein kinase (MAPK) cascades. This study was conducted to examine the impact of ethanol on MAPK signaling in HT22 cells. Ethanol (100 and 400 mM) caused activation of ERK, p38 MAPK, and JNK. ERK activation occurred in early time and p38 MAPK activation was evident when ERK activation was diminished. Specific inhibitor of p38 MAPK (SB203580) protected HT22 cells against ethanol, which was accompanied by an inhibition of ROS accumulation. However, inhibitors of ERK (U0126) and JNK (SP600125) had no effects on ethanol-induced neuronal cell death when they are treated with ethanol for 24 h. These results suggest that p38 MAPK may have important roles in ROS accumulation during ethanol-induced oxidative stress in HT22 cells.     

p38MAPK通路调控树突状细胞表达PD-L1的实验研究

目的探讨脂多糖刺激单核细胞源树突状细胞表达程序性死亡因子配体1(PD-L1)与p38MAPK信号通路的关系。方法体外培养树突状细胞,用p38抑制剂SB203580阻断p38MAPK通路后再用LPS刺激树突状细胞。光学显微镜观察各组细胞的形态变化;流式细胞术测定CD86和PD-L1表达的平均荧光强度;Western blot测定PD-L1蛋白表达。结果光镜下观察LPS刺激组细胞先经历梭型贴壁后逐渐恢复圆形,树突较多;SB203580和LPS共同刺激组细胞树突退化,未刺激组细胞成团悬浮,树突较多。SB203580和LPS共同刺激组细胞CD86、PD-L1较LPS刺激组的明显降低(P<0.05或P<0.01),与未刺激组的相比CD86差异无统计学意义,但PD-L1降低(P<0.05)。SB203580和LPS共同刺激组细胞PD-L1的蛋白表达量较其它两组的均明显减少(P<0.01或P<0.01)。结论 LPS通过p38MAPK信号通路调控树突状细胞表达PD-L1。     

The growth factor SVH-1 regulates axon regeneration in C. elegans via the JNK MAPK cascade

The ability of neurons to undergo regenerative growth after injury is governed by cell-intrinsic and cell-extrinsic regeneration pathways. These pathways represent potential targets for therapies to enhance regeneration. However, the signaling pathways that orchestrate axon regeneration are not well understood. In Caenorhabditis elegans, the Jun N-terminal kinase (JNK) and p38 MAP kinase (MAPK) pathways are important for axon regeneration. We found that the C. elegans SVH-1 growth factor and its receptor, SVH-2 tyrosine kinase, regulate axon regeneration. Loss of SVH-1-SVH-2 signaling resulted in a substantial defect in the ability of neurons to regenerate, whereas its activation improved regeneration. Furthermore, SVH-1-SVH-2 signaling was initiated extrinsically by a pair of sensory neurons and functioned upstream of the JNK-MAPK pathway. Thus, SVH-1-SVH-2 signaling via activation of the MAPK pathway acts to coordinate neuron regeneration response after axon injury.     

Regulation of p38 MAPK phosphorylation inhibits chondrocyte apoptosis in response to heat stress or mechanical stress

Activation of p38 MAPK has been associated with a stress response and with apoptotic processes. However, the function of p38 MAPK in chondrocytes is not clearly understood. In this study, we analyzed the expression of p38 MAPK in chondrocytes and investigated the function of p38 MAPK in response to heat stress and mechanical stress. Chondrocytes were isolated from human cartilage and cultured. Expression of p38 and phosphorylated p38 in cartilage of patients with osteoarthritis (OA) was compared to those in normal cartilage by immunohistochemistry and Western blotting. Human knee chondrocytes were exposed to heat stress or mechanical stress. Normal knee chondrocytes were pre-treated with SB203580 or p38 small interfering RNA (siRNA) before induction of heat stress or mechanical stress. Chondrocyte apoptosis was detected by TUNEL staining and Western blotting of cleaved caspases. OA and normal chondrocytes expressed p38; however, OA chondrocytes showed much higher phosphorylated p38 compared to normal chondrocytes. Heat stress or mechanical stress induced apoptosis and increased phosphorylated p38 in normal chondrocytes. The TUNEL positive cells and expression levels of phosphorylated p38 in response to stress decreased when chondrocytes were incubated with SB203580 or transfected with siRNA against p38. In conclusion, we have demonstrated that heat stress or mechanical stress increased chondrocyte apoptosis via phosphorylation of p38. Stress-induced chondrocyte apoptosis decreased due to inhibition of p38 MAPK activation. In contrast, the phosphorylation of p38 MAPK increased in OA chondrocytes. Our results show that down-regulation of p38 MAPK activation inhibits chondrocyte death induced by heat stress or mechanical stress.     

p38MAPK通路参与亚急性帕金森病模型小鼠黑质iNOS表达的调控

目的:研究1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)所致Parkinson病(PD)小鼠模型黑质p38丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)通路对诱导型一氧化氮合酶(inducible nitric oxide,iN-OS)、半胱氨酸蛋白酶-3(caspase-3)的表达调控,以探讨PD多巴胺能神经元丢失的可能机制。方法:采用MPTP制备PD小鼠模型,观察行为学变化;采用免疫组化和免疫蛋白印迹法,观察黑质区酪氨酸羟化酶(tyrosine hydroxylase,TH)、iNOS、caspase-3和磷酸化p38MAPK(p-p38MAPK)阳性细胞数和蛋白表达水平变化及给予p38MAPK特异性抑制剂SB203580后对上述变化的影响。结果:模型II组TH阳性神经元明显丢失,小鼠出现典型的PD样行为学表现;模型I组小鼠黑质区p-p38MAPK、iNOS、caspase-3阳性细胞数及蛋白水平显著增加。经SB203580处理后,上述变化明显减轻(P0.01)。结论:p38MAPK通路对PD模型小鼠黑质区细胞凋亡可能起重要的调控作用,抑制该通路具有一定神经保护作用。     

The effects of aging and oxidative stress on learning behavior in C. elegans

Oxidative stress is associated with age-related declines of biological functions. However, the nervous system is preserved during aging in Caenorhabditis elegans and, thus, it is not well explored whether aging and oxidative stress affect nervous functions. Here we report that age-related decline can be observed in a type of associative-learning behavior, referred to as isothermal tracking. We also report the effects of mutants with altered sensitivity to oxidative stress on learning behavior and motor activity in young adults. The isp-1 and clk-1 mutants are members of the Clk class of mutants and have deficits in the function of the mitochondrial respiratory chain, leading to reduced levels of oxidative stress, increased longevity, delayed rhythmic behaviors and other phenotypes. Both the Clk mutations and pretreatment with a metabolic antioxidant, alpha-lipoic acid (LA), increased the ability to show isothermal tracking and modestly reduced motor activity. Mutants with increased oxidative stress showed severely impaired learning behavior and modestly reduced motor activity. Therefore, physiological levels of oxidative stress may be too high for learning behavior but, perhaps, not for motor activity. We discuss the relevance of oxidative stress to the aging and evolution of behaviors.     

p38 MAPK信号通路参与受体介导的细胞内吞的调控

目的：观察p38 MAPK信号转导通路在受体介导的细胞内吞中的作用。方法：利用Alexa 594标记的转铁蛋白作为受体介导的内吞作用的观察指标，来研究p38特异性抑制剂SB203580或ERK通路特异性抑制剂PD98059预处理以及p38基因敲除对该过程的影响。 结果：在受体介导的细胞内吞中，p38被磷酸化激活。SB203580的预处理或p38基因的敲除都能阻断受体介导的细胞内吞，而PD98059的预处理对该过程没有影响。 结论：p38 MAPK信号转导通路参与了受体介导的细胞内吞的调控。     

The DAF-7 TGF-beta signaling pathway regulates chemosensory receptor gene expression in C. elegans

Regulation of chemoreceptor gene expression in response to environmental or developmental cues provides a mechanism by which animals can alter their sensory responses. Here we demonstrate a role for the daf-7 TGF-beta pathway in the regulation of expression of a subset of chemoreceptor genes in Caenorhabditis elegans. We describe a novel role of this pathway in maintaining receptor gene expression in the adult and show that the DAF-4 type II TGF-beta receptor functions cell-autonomously to modulate chemoreceptor expression. We also find that the alteration of receptor gene expression in the ASI chemosensory neurons by environmental signals, such as levels of a constitutively produced pheromone, may be mediated via a DAF-7-independent pathway. Receptor gene expression in the ASI and ASH sensory neurons appears to be regulated via distinct mechanisms. Our results suggest that the expression of individual chemoreceptor genes in C. elegans is subject to multiple modes of regulation, thereby ensuring that animals exhibit the responses most appropriate for their developmental stage and environmental conditions.     

Caveolin-1 confers antiinflammatory effects in murine macrophages via the MKK3/p38 MAPK pathway

Caveolin-1 has been reported to regulate apoptosis, lipid metabolism, and endocytosis in macrophages. In the present study, we demonstrate that caveolin-1 can act as a potent immunomodulatory molecule. We first observed caveolin-1 expression in murine alveolar macrophages by Western blotting and immunofluorescence microscopy. Loss-of-function experiments using small interfering RNA showed that down regulating caveolin-1 expression in murine alveolar and peritoneal macrophages increased LPS-induced proinflammatory cytokine TNF-alpha and IL-6 production but decreased anti-inflammatory cytokine IL-10 production. Gain-of-function experiments demonstrated that overexpression of caveolin-1 in RAW264.7 cells decreased LPS-induced TNF-alpha and IL-6 production and augmented IL-10 production. p38 mitogen-activated protein kinase (MAPK) phosphorylation was increased by overexpressing caveolin-1 in RAW264.7 cells, whereas c-Jun N-terminal kinase, extracellular signal-regulated kinase MAPK, and Akt phosphorylation were inhibited. The antiinflammatory modulation of LPS-induced cytokine production by caveolin-1 was significantly abrogated by the administration of p38 inhibitor SB203580 in RAW264.7 cells. Peritoneal macrophages isolated from MKK3 null mice did not demonstrate any modulation of LPS-induced cytokine production by caveolin-1. LPS-induced activation of NF-kappaB and AP-1 determined by electrophoretic mobility shift assay were significantly reduced by overexpressing caveolin-1 in RAW264.7 cells. The reductions were attenuated by the administration of p38 inhibitor SB203580. Taken together, our data suggest that caveolin-1 acts as a potent immunomodulatory effector molecule in immune cells and that the regulation of LPS-induced cytokine production by caveolin-1 involves the MKK3/p38 MAPK pathway.