Icariin upregulates phosphorylated cyclic adenosine monophosphate response element binding protein levels in the hippocampus of the senescence-accelerated mouse

At 8 weeks after intragastric administration of icariin to senescence-accelerated mice （P8 strain）, Morris water maze results showed that escape latency was shortened, and the number of platform crossings was increased. Immunohistochemical staining and western blot assay detected significantly increased levels of cyclic adenosine monophosphate response element binding protein These results suggest that icariin upregulates phosphorylated cyclic adenosine monophosphate response element binding protein levels and improves learning and memory functions in hippocampus of the senescence-accelerated mouse.

Effects of basic fibroblast growth factor on hippocampal and parietal cortical neuronal cAMP-response element-binding protein expression in a rat model of focal cerebral ischemia/reperfusion

BACKGROUND： cAMP-response element binding protein （CREB） is a key modulator of various signaling pathways. CREB activation initiates a series of intracellular signaling pathways that promote neuronal survival. OBJECTIVE： To investigate the regulatory effects of basic fibroblast growth factor （bFGF） on cerebral neuronal CREB expression following ischemia/reperfusion injury. DESIGN, TIME AND SETTING： An immunohistochemical detection experiment was performed at the Department of Anatomy, Shenyang Medical College, between October 2006 and April 2008. MATERIALS： A total of 60 healthy, adult, Wistar rats were randomly divided into three groups： sham-operated （n =12）, ischemia/reperfusion （n = 24）, and bFGF-treated （n = 24）. Rabbit anti-rat CREB （1： 100） and biotin labeled goat anti-rabbit IgG were purchased from the Wuhan Boster Company, China. MetaMorph-evolution MP5.0-BX51 microscopy imaging system was provided by China Medical University, China. METHODS： Rat models of cerebral ischemia/reperfusion injury were developed using the suture method for right middle cerebral artery occlusion. Two-hour ischemia was followed by reperfusion. Rats from the bFGF-treated and ischemia/reperfusion groups were intraperitoneally administered endogenous bFGF （500 IU/mL, 2 000 IU/kg） or an equal amount of physiological saline. Rats from the sham-operated group underwent a similar surgical procedure, without induction of ischemia/reperfusion injury and drug administration. MAIN OUTCOME MEASURES： After 48-hour reperfusion, hippocampal and parietal cortical neuronal CREB expression was detected by immunohistochemistry, and the absorbance of hippocampal CREB-positive products was determined using MetaMorph-evolutionMP5.0-BX51 microscopy imaging system. RESULTS： The sham-operated group exhibited noticeable CREB expression in hippocampal and parietal cortical neurons. In the ischemia/reperfusion group, the CREB expression was discrete and neurons were poorly arranged. The bFGF-treated group exhibited increased CREB expression and better neuronal arrangement compared with the ischemia/reperfusion group. The mean absorbance of CREB-immunoreactive products in the hippocampus and parietal cortex was significantly higher in the ischemia/reperfusion group than in the sham-operated group （P 〈 0.05）, and significantly higher in the bFGF-treated group than in the ischemia/reperfusion group （P 〈 0.05）. CONCLUSION： bFGF significantly upregulates CREB expression in hippocampal and parietal cortical neurons following ischemia/reperfusion injury.

Sevoflurane effects on cyclic adenosine monophosphate response element binding protein,phosphorylated cyclic adenosine monophosphate response element binding protein,and Livin expression in the cortex and hippocampus of a vascular cognitive impairment rat

BACKGROUND： Neuronal necrosis and apoptosis play important roles in the pathophysiology of cerebral ischemia and resulting cognitive impairment. However, inhibition of neuronal necrosis and apoptosis has been shown to attenuate cognitive impairment following cerebral ischemia. OBJECTIVE： To investigate the effects of sevoflurane on cyclic adenosine monophosphate response element binding protein （CREB）, phosphorylated CREB （pCREB）, and Livin expression in the cortex and hippocampus of a rat model of vascular cognitive impairment.DESIGN, TIME AND SETTING： A randomized, controlled experiment was performed in the Chongqing Key Laboratory of Neurology between June 2007 and July 2008.MATERIALS： Sevoflurane was provided by Abbott Laboratory, UK; Morris water maze was provided by Chinese Academy of Medical Sciences, China; goat anti-rat CREB, goat anti-rat pCREB and goat anti-rat Livin antibodies were provided by Biosource International, USA. METHODS： A total of 42 female, Wistar rats were randomly assigned to the following groups： sham operation, vascular cognitive impairment, and sevoflurane treatment. The vascular cognitive impairment rat model was established by permanent bilateral occlusion of both common carotid arteries, and 1.0 MAC sevoflurane was immediately administered by inhalation for 2 hours. MAIN OUTCOME MEASURES： CREB, pCREB, and Livin expression was measured in the cortex and hippocampus by Western blot and reverse transcription-polymerase chain reaction. Behavior was evaluated with Morris water maze. RESULTS： CREB, pCREB, and Livin expression in the sevoflurane treatment group was significantly greater than the vascular cognitive impairment group （P 〈 0.01）. However, expression of CREB and pCREB was significantly less in the sevoflurane treatment and vascular cognitive impairment groups, compared with the sham operation group （P 〈 0.01）. Livin expression in the sevoflurane treatment and vascular cognitive impairment groups was significantly greater than the sham operation group （P 〈 0.01）. Learning, memory, and behavior disorders were observed in the vascular cognitive impairment group. Sevoflurane treatment significantly improved these observed disorders. CONCLUSION： Sevoflurane improved cognitive impairment due to permanent bilateral occlusion of both common carotid arteries. Improved function was associated with increased CREB, pCREB, and Livin expression in the cortex and hippocampus.

肉桂醛调节AMPK/SREBP1c信号通路对非酒精性脂肪性肝炎小鼠肝损伤的影响

【目的】探讨肉桂醛通过调节腺苷酸活化蛋白激酶(AMPK)/胆固醇调节元件结合蛋白1c(SREBP1c)信号通路对非酒精性脂肪性肝炎(NASH)小鼠肝损伤的影响。【方法】实验随机分为正常组,模型组,肉桂醛低、中、高剂量组及肉桂醛高剂量+Compound C(AMPK抑制剂)组,每组15只小鼠。除正常组,其他各组给予高脂饲料喂养构建NASH模型。干预治疗后,观察肝组织病理形态变化,检测血清生化指标[丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、甘油三酯(TG)、总胆固醇(TC)],肝组织氧化应激指标[丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽(GSH)],AMPK/SREBP1c通路蛋白[磷酸化AMPK(p-AMPK)、AMPK、SREBP1c、乙酰辅酶A羧化酶(ACC)、磷酸化ACC(p-ACC)、肉毒碱棕榈酰转移酶1(CPT1)、硬脂酰辅酶A去饱和酶1(Scd1)]表达,及CPT1α、长链酯酰辅酶A脱氢酶(Lcad)、ACC1、脂肪酸合成酶(FAS)的mRNA表达水平。【结果】与正常组比较,模型组肝脏脂肪变性,脂质沉积和纤维化间质增多,ALT、AST、TG、TC,MDA含量,SREBP1c、Scd1蛋白表达,ACC1、FAS mRNA表达水平显著升高,SOD、GSH活性,p-AMPK、AMPK、p-ACC、ACC、CPT1蛋白表达,CPT1α、Lcad m RNA表达水平显著降低(P<0.05);与模型组比较,肉桂醛低、中、高剂量组脂质沉积和纤维化间质减少,ALT、AST、TG、TC、MDA含量,SREBP1c、Scd1蛋白表达,ACC1、FAS mRNA表达水平显著降低,SOD、GSH活性,p-AMPK、AMPK、p-ACC、ACC、CPT1蛋白表达,CPT1α、Lcad mRNA表达水平显著升高(P<0.05),且呈剂量依赖性;与肉桂醛高剂量组比较,肉桂醛高剂量+Compound C组上述指标均被逆转(P<0.05)。【结论】肉桂醛可能通过调控AMPK/SREBP1c通路,抑制氧化应激,改善肝脏脂肪变性,减轻NASH小鼠肝损伤。

Tonicity response element binding protein associated with neuronal cell death in the experimental diabetic retinopathy

AIM: To study the contribution of tonicity response element binding protein(Ton EBP) in retinal ganglion cell(RGC) death of diabetic retinopathy(DR).METHODS: Diabetes was induced in C57BL/6 mice by five consecutive intraperitoneal injections of 55 mg/kg streptozotocin(STZ). Control mice received vehicle(phosphate-buffered saline). All mice were killed 2mo after injections, and the extent of cell death and the protein expression levels of Ton EBP and aldose reductase(AR) were examined.RESULTS: The Ton EBP and AR protein levels and the death of RGC were significantly increased in the retinas of diabetic mice compared with controls 2mo after the induction of diabetes. Terminal deoxynucleotidyl transferase(Td T)-mediated d UTP nick end labeling(TUNEL)-positive signals co-localized with Ton EBP immunoreactive RGC. These changes were increased in the diabetic retinas compared with controls.CONCLUSION: The present data show that AR and Ton EBP are upregulated in the DR and Ton EBP may contribute to apoptosis of RGC in the DR.

基于AMPK/SREBP-1c分子通路的山楂原花青素调控脂质代谢机制

目的:探讨山楂原花青素(hawthorn procyanidins,HPC)调节腺苷酸激活蛋白激酶/固醇调节元件结合蛋白(AMP-activated protein kinase/sterol regulatory element binding protein-1c,AMPK/SREBP-1c)信号通路对脂质代谢的影响及其机制。方法:采用随机数字表法将大鼠分为空白对照组(blank control group,BCG),高脂血症模型组(hyperlipidemia model group,HMG),HPC低、中、高剂量组(HPC-low-, medium-and high-dose groups,HPC-LDG、HPC-MDG、HPC-HDG),非诺贝特阳性对照组(fenofibrate positive control group,FPG),每组10只。按试剂盒方法检测大鼠血清和肝匀浆中甘油三酯(triglyceride,TG)、总胆固醇(total cholesterol,TC)、低密度脂蛋白胆固醇(lowdensitylipoproteincholesterol,LDL-C)和高密度脂蛋白胆固醇(highdensity lipoproteincholesterol,HDL-C)浓度;苏木精-伊红(hematoxylineosin,HE)染色观察各组大鼠肝脏组织病理学变化;实时定量聚合酶链式反应检测各组大鼠肝脏中AMPK、SREBP-1c、甘油-3-磷酸酰基转移酶(glycerol-3-phosphate acyltransferase-1,GPAT1)、乙酰辅酶羧化酶(acetyl CoA carboxylase,ACC)、脂肪酸合成酶(fatty acid synthese,FAS)、肉毒碱棕榈酰基转移酶(carnitine palmitoyltransterase-1,CPT1)和过氧化物酶体增殖物激活受体γ辅助激活因子1α(peroxisome proliferator activated receptor γ coactivator-1α,PGC-1α)mRNA表达水平;蛋白质免疫印迹法(Western blot)检测各组大鼠肝脏中p-AMPK、SREBP-1c、GPAT1、ACC、FAS、CPT1和PGC-1α蛋白表达水平。结果:造模7周后,与BCG比较,HMG大鼠体质量、肝质量和肝脏指数均显著或极显著升高(P<0.05、P<0.01)。与HMG比较,HPC-HDG和FPG大鼠血清和肝匀浆TG、TC和LDL-C浓度极显著下降,HDL-C浓度极显著升高(P<0.01),且HPC对大鼠血清和肝匀浆中脂质浓度影响有剂量依赖性。采用各剂量HPC预防性干预后,随HPC剂量增加,大鼠肝细胞脂肪变性逐渐改善。与HMG比较,HPC-HDG和FPG大鼠肝脏AMPK mRNA和p-AMPK蛋白相对表达量均极显著上升(P<0.01),大鼠肝脏SREBP-1c、GPAT1、ACC、FAS mRNA和蛋白相对表达量均极显著下降(P<0.01),大鼠肝脏CPT1、PGC-1α mRNA和蛋白相对表达量均极显著升高(P<0.01)。结论:HPC可以改善高脂血症大鼠脂质代谢,其作用机制可能与AMPK/SREBP-1c分子信号通路有关。

cAMP/CREB/BDNF信号通路在沃替西汀抗小鼠抑郁样行为中的作用

目的研究新型抗抑郁药沃替西汀对环磷酸腺苷/环磷酸腺苷反应元件结合蛋白/脑源性神经营养因子(c AMP/CREB/BDNF)信号转导通路的影响。方法将昆明小鼠随机分为对照组和慢性不可预知性温和应激(CUMS)造模组进行造模,采用糖水偏爱试验考察模型是否成功建立。造模结束后将CUMS组小鼠随机分为模型组、氟西汀组和沃替西汀组。采用悬尾试验、强迫游泳试验和旷场试验,考察沃替西汀对抑郁小鼠的抗抑郁作用。采用ELISA试剂盒检测小鼠海马组织中c AMP的含量。采用蛋白免疫印迹法检测小鼠海马组织中磷酸化CREB(p CREB)和BDNF的蛋白表达。结果沃替西汀显著缩短小鼠在悬尾和强迫游泳试验中的不动时间(P<0.01),而对其在旷场试验中的自主活动行为没有影响(P>0.05),表明沃替西汀可改善抑郁小鼠的抑郁样行为;ELISA结果显示沃替西汀能显著增加小鼠海马组织内c AMP的含量(P<0.01);蛋白免疫印迹结果表明沃替西汀可以促进p CREB和BDNF的蛋白表达(P<0.01)。结论沃替西汀产生抗抑郁作用机制可能与影响c AMP/CREB/BDNF信号转导通路有关。

cAMP反应元件结合蛋白介导磷酸化细胞外信号调节激酶在神经病理性痛形成中的作用

采用行为学、免疫组织化学和Western blot方法,观察鞘内注射细胞外信号调节激酶(extracellular signal-regulate kinase, ERK)信号转导通路阻滞剂对慢性压迫性损伤(chronic constriction injury,CCI)大鼠痛行为及脊髓背角内磷酸化cAMP反应元件结合蛋白(phosphorylated cAMP response-element binding protein,pCREB)和Fos表达变化的影响,探讨ERK/CREB转导通路在神经病理性疼痛中的作用。结果表明,CCI可明显增加双侧脊髓背角pCREB、损伤侧脊髓背角浅层Fos阳性神经元表达,以CCI后3与5d时尤为显著。鞘内注射促分裂原活化蛋白激酶激酶(mitogen-activated protein kinase kinase,MEK)阻滞剂U0126及ERK反义寡核苷酸在减轻大鼠痛行为的同时,能叫显抑制双侧脊髓背角内pCREB的表达,同时,Fos阳性神经元的表达也明显减少。大鼠痛行为及脊髓背角pCREB和Fos的表达在时相上一致。上述结果提示pCREB参与pERK介导的神经病理性疼痛。

降钙素基因相关肽对局灶性脑缺血再灌注大鼠脑cAMP反应元件结合蛋白mRNA表达的影响

目的探讨外源性降钙素基因相关肽(CGRP)对局灶性脑缺血再灌注大鼠海马和顶叶皮质cAMP反应元件结合蛋白(CREB)mRNA表达的影响。方法用线栓法制作大鼠局灶性脑缺血再灌注模型,应用原位杂交和图像分析技术检测大鼠缺血侧海马CA1区和顶叶皮质CREB mRNA表达。结果假手术组右侧海马CA1区和顶叶皮质CREB mRNA有明显表达,缺血再灌注组右侧海马CA1区和顶叶皮质CREB mRNA阳性产物吸光度值减少,CGRP组缺血侧海马CA1区和顶叶皮质CREB mRNA表达的吸光度值比缺血再灌注组增高(P<0.05)。结论CGRP上调局灶性脑缺血再灌注大鼠海马和顶叶皮质CREB mRNA的表达,CGRP对缺血神经元的保护作用可能通过激活CREB的转录与翻译,从而启动一系列信号通路来实现。

癫癎持续状态对发育期大鼠学习记忆及海马磷酸化的c-AMP反应元件结合蛋白表达的影响

目的探讨癫癎持续状态(SE)对发育期大鼠学习记忆功能及海马磷酸化的c-AMP反应元件结合蛋白(pCREB)表达的影响。方法6周龄SD大鼠32只随机分为SE组和9g/L盐水对照组(NS组)。戊四氮(PTZ)诱导发育期大鼠SE。采用Morris水迷宫和Y迷宫观察大鼠学习记忆功能的改变,应用免疫组织化学方法检测大鼠海马各区pCREB的表达。结果与NS组比较,SE组在Morris水迷宫测试中平均逃避潜伏期明显延长(P<0.05),原平台所在象限的游泳时间明显缩短(P<0.05);Y迷宫中达标所需的训练次数显著增多(P<0.05),24h记忆保持率明显降低(P<0.05)。海马CA1区和齿状回(DG)区pCREB表达显著下调(P<0.05)。结论SE可使发育期大鼠学习记忆功能受损,其机制可能与海马pCREB表达减少有关。

cAMP反应元件结合蛋白在药物依赖形成中的作用

反复应用成瘾性药物引起中枢神经系统特定部位cAMP信号系统出现适应性改变 ,cAMP反应元件结合蛋白(cyclicAMPresponseelementbindingprotein ,CREB)是受cAMP调节的主要转录因子 ,在动物产生药物依赖时脑内CREB含量及磷酸化程度发生变化 ,与动物躯体依赖和精神依赖有关。

CGRP及NGF对局灶性脑缺血再灌注大鼠海马cAMP反应元件结合蛋白磷酸化的影响

目的探讨外源性降钙素基因相关肽(CGRP)及神经生长因子(NGF)对局灶性脑缺血再灌注大鼠海马cAMP反应元件结合蛋白(CREB)和磷酸化CREB(p-CREB)表达的影响。方法用线栓法阻塞大鼠右侧大脑中动脉制作局灶性脑缺血再灌注模型,应用免疫组织化学SABC法、Western blotting和图像分析方法检测大鼠手术侧海马CA1区CREB和p-CREB表达。结果缺血再灌注组海马CA1区CREB表达较假手术组减少,p-CREB表达高于假手术组(P<0.05);CGRP组和NGF组CA1区的CREB和p-CREB表达均高于缺血再灌注组(P<0.05);CGRP与NGF联合应用时CREB和p-CREB表达分别高于CGRP组和NGF组(P<0.05)。结论CGRP及NGF上调局灶性脑缺血再灌注大鼠海马CREB和p-CREB的表达,CGRP与NGF联合应用则作用更强,CGRP及NGF对缺血神经元的保护作用可能是通过上调神经元内CREB和p-CREB来实现的,CGRP与NGF对缺血神经元的保护有协同作用。

cAMP对转化细胞中几种基因表达及CREB DNA结合活性的影响

从癌基因、抑癌基因及转录因子 CREB(c AMP反应序列结合蛋白 )对 CRE DNA序列结合活性的相关性 ,对 db- c AMP处理的小鼠 C3H10 T1 /2转化细胞增殖抑制作用进行了研究 .实验结果表明 ,转化细胞中 PKA(蛋白激酶 A)活性显著低于正常细胞 ,而 PKC(蛋白激酶 C)活性则显著高于正常细胞 .斑点印迹和 Northern印迹分析显示转化细胞中 c- myc和 Ca M(钙调素 )基因表达明显高于正常细胞 ,而 p53基因和 Rb基因表达则明显低于正常细胞 ,这些差别与 C3H10 T1/ 2 转化细胞增殖失控有关 .转化细胞经 db- c AMP(1 mmol/L)处理后 ,细胞增殖受到明显抑制 ,db- c AMP处理0 .5h后 ,转化细胞中 PKA活性便明显增强 ,PKC活性则被显著抑制 ,处理 2 h后 ,c- myc和 Ca M基因表达下降 ,而 p53和 Rb基因表达则增强 ,这些变化与 c AMP抑制 C3H10 T1/ 2 转化细胞增殖有密切联系 .凝胶阻滞电泳分析显示 db- c AMP(1 mmol/L )处理短时间内 ,CREB对 CRE DNA序列无结合活性 ,1 2 h后开始出现较弱的结合活性 ,2 4 h后才明显加强 ,表明在 db- c AMP处理的早期 ,调控区中含有 CRE序列的基因不参与 db- c AMP对细胞增殖抑制的调节 ,即与 CREB磷酸化及其相应的 DNA结合活性无相关性 .

c-di-AMP——细菌中第二信使的研究进展

环二腺苷酸(cyclic diadenylate monophosphate,c-di-AMP)是新发现的在细菌中广泛存在的一类重要的第二信使。c-di-AMP不仅与细菌的生长、细胞壁的代谢平衡、生物被膜的形成等密切相关,还在真核宿主细胞抗感染的固有免疫中发挥重要作用。主要从c-di-AMP的合成酶与降解酶、c-di-AMP在病原菌中的结合蛋白以及c-di-AMP与宿主细胞互作过程中的相关受体蛋白等几方面进行综述。

参苓白术散调节AMPK、ABCG2改善高尿酸血症模型小鼠尿酸的实验研究

目的明确参苓白术散调节AMP活化蛋白激酶(AMP-activated protein kinase,AMPK)/ATP结合盒转运体G2(ATP-binding cassette transporter G2,ABCG2)通路降低高尿酸血症(hyperuricemia,HUA)模型小鼠尿酸(uric acid,UA)的作用机制。方法将36只雄性昆明小鼠随机分为空白组、模型组、中药组、西药组4组。空白组除外,其余各组腹腔注射氧嗪酸钾悬液(0.6 g/kg)连续7 d,建立HUA小鼠模型,参苓白术散干预14 d;采用生化法检测血清UA、谷草转氨酶(aspartate aminotransaminase,AST)、谷丙转氨酶(alanine aminotransferase,ALT)含量,ELISA法检测血清半胱氨酸蛋白酶抑制剂C(cystatin C,CysC)含量,HE染色法观察肝、肾、回肠组织病理变化,Western blot检测回肠组织ABCG2、磷酸化的AMPK(phosphorylated AMPK,p-AMPK)表达,RT-qPCR检测ABCG2 mRNA表达。结果与空白组比较,模型组UA、CysC含量均显著升高(P<0.01),p-AMPK、ABCG2蛋白及ABCG2 mRNA含量均明显降低(P<0.01)。与模型组比较,西药组和中药组UA含量均显著降低(P<0.01),p-AMPK、ABCG2蛋白及ABCG2 mRNA含量均明显升高(P<0.01);中药组CysC含量显著降低(P<0.01)。空白组肾小球大小均匀,结构清晰;模型组肾间质有炎性细胞浸润,上皮细胞轻微脱落;中药组及西药组上皮细胞脱落症状有所改善。空白组回肠组织黏膜皱襞规则,肠绒毛完整、整齐、密集;模型组肠绒毛短小,隐窝深度变浅,肠黏膜上皮细胞损伤;西药组和中药组肠黏膜上皮细胞损伤有所改善。参苓白术散对肝功能及肝组织形态均无明显损伤。结论参苓白术散通过调节HUA小鼠肠组织AMPK磷酸化,升高ABCG2表达,降低血清UA含量以治疗HUA,且无肝功能损伤。

MicroRNA-185-5p mediates regulation of SREBP2 expression by hepatitis C virus core protein

AIM: To investigate the molecular mechanism for regulation of cholesterol metabolism by hepatitis C virus(HCV) core protein in Hep G2 cells.METHODS: HCV genotype 1b core protein was cloned and expressed in Hep G2 cells. The cholesterol content was determined after transfection. The expression of sterol regulatory element binding protein 2(SREBP2) and the rate-limiting enzyme in cholesterol synthesis(HMGCR) was measured by quantitative real-time PCR and immunoblotting after transfection. The effects of core protein on the SREBP2 promoter and 3'-untranslated region were analyzed by luciferase assay. We used different target predictive algorithms, micro RNA(mi RNA) mimics/inhibitors, and site-directed mutation to identify a putative target of a particular mi RNA.RESULTS: HCV core protein expression in Hep G2 cells increased the total intracellular cholesterol level(4.05 ± 0.17 vs 6.47 ± 0.68, P = 0.001), and this increase corresponded to an increase in SREBP2 and HMGCR m RNA levels(P = 0.009 and 0.037, respectively) and protein expression. The molecular mechanism studyrevealed that the HCV core protein increased the expression of SREBP2 by enhancing its promoter activity(P = 0.004). In addition, mi R-185-5p expression was tightly regulated by the HCV core protein(P = 0.041). Moreover, overexpression of mi R-185-5p repressed the SREBP2 m RNA level(P = 0.022) and protein expression. In contrast, inhibition of mi R-185-5p caused upregulation of SREBP2 protein expression. mi R-185-5p was involved in the regulation of SREBP2 expression by HCV core protein. CONCLUSION: HCV core protein disturbs the cholesterol homeostasis in Hep G2 cells via the SREBP2 pathway; mi R-185-5p is involved in the regulation of SREBP2 by the core protein.

Transthyretin—A Key Gene Involved in Regulating Learning and Memory in Brain, and Providing Neuroprotection in Alzheimer Disease via Neuronal Synthesis of Transthyretin Protein

Transthyretin (TTR), a carrier protein present in the liver and choroid plexus of the brain, has been shown to be responsible for binding thyroid hormone thyroxin (T4) and retinol in plasma and cerebrospinal fluid (CSF). TTR aids in sequestering of beta-amyloid peptides Aβ deposition, and protects the brain from trauma, ischemic stroke and Alzheimer disease (AD). Accordingly, hippocampal gene expression of TTR plays a significant role in learning and memory as well as in simulation of spatial memory tasks. TTR via interacting with transcription factor CREB regulates this process and decreased expression leads to memory deficits. By different signaling pathways, like MAPK, AKT, and ERK via Src, TTR provides tropical support through megalin receptor by promoting neurite outgrowth and protecting the neurons from traumatic brain injury. TTR is also responsible for the transient rise in intracellular Ca2+ via NMDA receptor, playing a dominant role under excitotoxic conditions. In this review, we tried to shed light on how TTR is involved in maintaining normal cognitive processes, its role in learning and memory, under memory deficit conditions;by which mechanisms it promotes neurite outgrowth;and how it protects the brain from Alzheimer disease (AD).

HCV NS5A通过抑制p-AMPK并上调固醇调节元件结合蛋白2及HMG-CoA还原酶促进小鼠肝细胞胆固醇合成

已有研究证明,丙型肝炎病毒(HCV)非结构蛋白5A(NS5A)可诱导肝细胞脂肪变性。本文报告,HCV NS5A刺激肝细胞胆固醇合成,引起脂代谢失调,促进肝脂肪变性。首先,我们构建了由小鼠甲胎蛋白增强子和小鼠白蛋白启动子驱动的NS5A及NS5A domainⅠ、Ⅱ和Ⅲ的慢病毒表达载体,包装成病毒颗粒后通过尾静脉注射感染小鼠。小鼠血清总胆固醇测定及肝组织切片苏木精-伊红染色揭示,与模拟注射对照及增强绿色荧光蛋白(EGFP)慢病毒颗粒处理小鼠比较,NS5A慢病毒颗粒处理小鼠血清总胆固醇水平明显升高;肝细胞内脂滴明显增多。免疫组化和RTq PCR分析显示,胆固醇合成的关键调节酶HMG-CoA还原酶(HMGCR)在NS5A慢病毒处理的小鼠肝内表达显著升高。蛋白质印迹结果证明,与模拟注射及EGFP慢病毒颗粒处理的小鼠比较,NS5A慢病毒颗粒处理的小鼠肝细胞磷酸化的腺苷一磷酸活化蛋白激酶(p-AMPK)水平明显降低,而固醇调节元件结合蛋白2(SREBP-2)及其靶基因HMGCR的水平显著升高。进一步研究发现,NS5A domainⅡ慢病毒颗粒处理的小鼠肝细胞p-AMPK、SREBP-2和HMGCR表达水平与全长NS5A慢病毒处理的小鼠相似。上述结果提示,HCV NS5A蛋白可通过抑制AMPK磷酸化激活,上调SREBP-2而促进胆固醇合成的限速酶HMGCR的表达,从而促进小鼠肝细胞胆固醇合成。上述结果还提示,NS5A domainⅡ可能是全长NS5A蛋白调节HMGCR基因表达的有效片段。总之,本研究证明,HCV NS5A可引起胆固醇代谢紊乱,这可能是慢性HCV感染引起肝脂肪变性的机制之一。很遗憾,在本研究中,尚未测定SREBP-1的靶基因乙酰CoA羧化酶(脂肪酸合成的限速酶)的表达,相关实验正在进行中。

Effects of Mg2+ on the binding of the CREB/CRE complex:Full-atom molecular dynamics simulations

Metal ions play critical roles in the interaction between deoxyribonucleic acid(DNA) and protein.The experimental research has demonstrated that the Mg^2+ ion can affect the binding between transcription factor and DNA.In our work,by full-atom molecular dynamic simulation, the effects of the Mg^2+ ion on the cyclic adenosine monophosphate(cAMP)response element binding protein(CREB)/cAMP response elements(CRE) complex are investigated.It is illustrated that the number of hydrogen bonds formed at the interface between protein and DNA is significantly increased when the Mg^2+ ion is added.Hence, an obvious change in the structure of the DNA is observed.Then the DNA base groove and base pair parameters are analyzed.We find that, due to the introduction of the Mg2+ ion, the DNA base major groove becomes narrower.A potential mechanism for this observation is proposed.It is confirmed that the Mg^2+ ion can enhance the stability of the DNA–protein complex.

Effect of ChREBP on carbohydrate feeding regulation in mandarin fish Siniperca chuatsi

Carnivorous fish have poor tolerance to carbohydrate in feed and low utilization rate of carbohydrate.Therefore,the balance of carbohydrate and lipids in the nutrient metabolism of carnivorous fish,the ef fective conversion and utilization of carbohydrate and lipids,and the feedback regulation of feeding are the key links for the e fficient utilization of carnivorous fish feed.Carbohydrate response element binding protein(ChREBP)is a new transcription factor found in recent years in the glucose signaling pathway,and can also participate in feeding regulation.We performed in-vivo and in-vitro experiments to reveal the role of ChREBP in the glucose metabolism and feeding in mandarin fish.The mRNA expression of ChREBP and appetite regulatory factors were measured after intraperitoneal injection of glucose in mandarin fish Siniperca chuatsi and cotransfection with glucose and glucose+siRNA in the hypothalamic cells in mandarin fish.The results reveal that at hour 2 and 4 post intraperitoneal injection with 1 mg/g BW glucose,the blood glucose level of the mandarin fish increased significantly,but food intake decreased significantly,and it also displayed a significantly increased ChREBP mRNA expression levels in liver.At hour 4 post injection,hypothalamic ChREBP mRNA level was significantly increased,whereas the mRNA expression levels of appetite genes neuropeptide Y(npy)and agouti-related peptide(AgRP)were decreased significantly.When the glucose concentration was 40 mmol/L,the expression level of ChREBP mRNA in mandarin fish hypothalamic cells was significantly up-regulated,but the expression level of appetite gene npy mRNA was down-regulated.When siRNA and glucose were co-transfected into mandarin fish brain cells,the expression level of chrebp mRNA was significantly decreased,and the appetite gene npy mRNA was significantly increased.The results indicated that glucose regulated food intake through the modulation of appetite gene npy by ChREBP.