Hyperbaric oxygen therapy activates CREB/BDNF signaling pathway to reduce synaptic damage in hippocampal neurons of Alzheimer disease mice

AIM To investigate the effect of hyperbaric oxygen (HBO) on synaptic damage of hippocampal neurons in APP/PS1 transgenic (TG) mice and its possible mechanism. METHODS The 6-month-old male APP/PS1 TG mice were randomly divided into TG group, HBO group and cAMP response element binding protein (CREB) inhibitor H89 group, with 10 mice in each group. Ten male wild-type (WT) C57BL/6 mice of the same age were used as negative control group (WT group). The mice in HBO and H89 groups were treated with HBO for 6 cycles, while the mice in WT group and TG group were not treated. The learning and memory abilities were observed by Morris water maze. The nesting ability of the mice was detected by nesting test. The Nissl bodies in hippocampal neurons were observed by Nissl staining. The mRNA expression of CREB and brain-derived neurotrophic factor (BDNF) in hippocampus was detected by real-time PCR. The protein levels of synapsin (SYN), postsynaptic density protein 95 (PSD95), growth-associated protein 43 (GAP43), CREB, phosphorylated CREB (p-CREB) and BDNF in the hippocampus were determined by Western blot. RESULTS Compared with WT group, the learning and memory abilities of the mice in TG group were signilficantly reduced (P<0.05). In addition, the nesting score, the number of Nissl bodies in the hippocampal neurons, the mRNA expression of CREB and BDNF, and the protein levels of SYN, PSD95, GAP43, p-CREB and BDNF were also decreased significantly (P<0.05). Compared with TG group, the learning and memory abilities of the mice in HBO group were improved (P<0.05). Meanwhile, the nesting scores of the mice were significantly increased (P<0.05), the neurons in the hippocampus were arranged neatly, and the number of Nissl bodies, the relative mRNA expression of CREB and BDNF,and the protein levels of SYN, PSD95, GAP43, p-CREB and BDNF were also increased significantly (P<0.05). Compared with HBO group, the mice in H89 group had poor learning and memory abilities, lowered nesting scores and decreased number of Nissl bodies. Futhermore, the relative mRNA expression of CREB and BDNF, and the protein levels of SYN, PSD95, GAP43, p-CREB and BDNF were also decreased significantly (P<0.05). CONCLUSION HBO improves the learning and memory abilities of APP/PS1 TG mice, and its mechanism may be related to activating the CREB/BDNF signaling pathway to reduce synaptic damage of hippocampal neurons in mice.     

干扰CREB基因对奶山羊乳腺上皮细胞脂质合成相关基因表达及甘油三酯合成的影响

旨在筛选奶山羊cAMP应答元件结合蛋白CREB（cAMP response element binding protein）基因的siRNA,揭示干扰该基因后对乳腺上皮细胞中乳脂合成相关基因表达及甘油三酯合成的影响。本研究通过qRT-PCR方法从西农萨能奶山羊乳腺组织中扩增CREB基因完整的CDS区,进行序列分析和不同泌乳时期表达水平分析,合成靶向CREB基因的siRNA,利用荧光定量PCR筛选有效siRNA,并检测脂质合成相关基因的表达,采用试剂盒检测细胞内甘油三酯含量。结果表明：1）克隆得到全长为984 bp的奶山羊CREB基因的CDS区（GenBank登录号：MK158073）,并对其进行生物信息学分析。2）该基因在奶山羊泌乳盛期乳腺组织的表达量为干奶期的1.93倍（P<0.05）。3）成功筛选到靶向CREB基因的有效siRNA,干扰效率为72%（P<0.01）;并将其在奶山羊乳腺上皮细胞进行转染,通过qRT-PCR检测脂质合成相关基因的表达,与对照组相比,干扰CREB基因后显著抑制了FASN、ACACA、SCD1、FABP3、LPL、CPT1B、GPAM和DGAT2基因表达量（P<0.05）,并显著增加了HSL基因表达量（P<0.05）;且细胞内甘油三酯含量被显著下调（P<0.05）。综上所述,CREB基因在奶山羊原代乳腺上皮细胞中很可能通过调控脂质代谢相关基因的表达及甘油三酯含量对山羊的乳脂合成过程发挥重要作用。     

Diminished expression of ACTH signaling proteins and steroidogenic limiting factors in adrenocortical cells isolated from halothane nn pigs

Previous studies demonstrated significantly lower plasma cortisol level in homozygous halothane-positive (Hal nn) pigs, as compared with homozygous halothane-negative (Hal NN) pigs. To determine whether such difference is attributed to the fundamental alterations in adrenocortical function, F1 offsprings from Pietrain (Hal nn)xErhualian (Hal NN) were intercrossed to produce F2 sibling pigs with segregated genotypes. Adrenocortical cells were isolated from the Hal nn and Hal NN F2 pigs, respectively, and cultured with or without ACTH challenge. Cortisol levels in culture medium, as well as the content of MC2R, cAMP, CREB, phosphorylated CREB (pCREB), StAR and P450scc in adrenocortical cell lysates, were determined. Cortisol, cAMP, StAR and P450scc levels were significantly lower in Hal nn adrenocortical cells under basal condition without ACTH challenge. ACTH significantly increased cortisol level in the medium and the protein content of MC2R, StAR, P450scc in adrenocortical cell lysates, regardless of genotypes. Total CREB protein content was not different between genotypes and treatments, whereas pCREB content exhibited significant effects of genotype and treatment, being higher in Hal NN than in Hal nn under basal condition and in response to ACTH challenge. These results indicate that the compromised cAMP/PKA/pCREB signaling pathway of ACTH and diminished expression of limiting factors in adrenocortical steroidogenesis (StAR and P450scc) may contribute to the significantly lower plasma cortisol levels in Hal nn pigs.     

CREB转录因子及其磷酸化信号通路的研究进展

cAMP反应元件结合蛋白（cAMP response element binding protein,CREB）是一种真核生物细胞核内调控因子,在神经元再生、突触形成及学习记忆等方面具有重要的调节作用。CREB的磷酸化是实现调节转录的重要途径,胞外信号途径影响CREB的磷酸化来激活多种靶基因转录,表现出多种生理功能。综述了CREB的结构、调控机制,特别是磷酸化的信号通路。     

牛MARK2、CREB5基因的克隆和生物信息学分析

试验旨在对牛MARK2、CREB5基因进行克隆和生物信息学分析.首先在GenBank数据库中利用人MARK2和CREB5基因序列比对获得牛的表达序列标签(ESTs)的序列,进行引物设计并利用RT-PCR方法从牛肩胛骨肌肉中克隆出MARK2和CREB5基因的cDNA序列,补足空缺部分,最终获得牛MARK2和CREB5基因.通过对牛MARK2和CREB5基因的生物学特性进行分析可知:牛MARK2基因的编码区长为2 076 bp,编码691个氨基酸,CREB5基因的编码区长1 527 bp,编码508个氨基酸;经蛋白质理化性质预测MARK2和CREB5蛋白均为亲水性蛋白;MARK2和CREB5蛋白的磷酸化位点均分布于苏氨酸(Thr)、丝氨酸(Ser)和酪氨酸(Tyr)残基上;MARK2蛋白与CREB5蛋白的二级结构预测以无规则卷曲为主;亚细胞定位预测MARK2蛋白主要分布在细胞质中,CREB5蛋白主要分布在细胞核中,两者均不属于分泌型蛋白;MARK2蛋白保守结构域预测含1个S_TKc和1个UBA功能结构域,CREB5蛋白保守结构域预测含有1个ZnF_C2H2、1个BRLZ功能结构域和5个低复杂度区域且二者均不具有跨膜结构.     

补阳还五汤对去势脑缺血雌性大鼠海马神经干细胞增殖及ERK/CREB信号通路的影响

目的 探讨补阳还五汤对去势脑缺血雌性大鼠海马神经干细胞（neural stem cells,NSCs）增殖及ERK/CREB信号通路的影响。方法 采用双侧卵巢切除术（OVX）结合大脑中动脉阻塞（MCAO）法复制去势雌性大鼠脑缺血复合模型,将造模后的36只大鼠随机分为双假手术组、复合模型组、雌激素组、雌激素+G15组、补阳还五汤组及补阳还五汤+G15组6组,每组6只,术后24 h给予相应药物灌胃连续干预14 d,同时每天腹腔注射BrdU、G15分别标记增殖细胞和阻断GPER-1。采用免疫荧光BrdU/Nestin双标法检测各组大鼠缺血侧海马齿状回NSCs增殖情况,免疫组化SP法检测ERK1/2、CREB1磷酸化蛋白表达水平。结果 补阳还五汤组和雌激素组缺血侧海马DG区BrdU/Nestin双标阳性细胞及pERK1/2、pCREB1阳性细胞表达均增加,与复合模型组比较有显著性差异（P<0.05）,但补阳还五汤组要多于雌激素组（P<0.05）。与补阳还五汤组比较,补阳还五汤+G15组缺血侧海马DG区BrdU/Nestin双标阳性细胞及及pERK1/2、pCREB1阳性细胞表达均减少（P<0.05）。结论 补阳还五汤可以促进去势脑缺血雌性大鼠缺血侧海马DG区神经干细胞增殖,激活ERK/CREB信号通路,可能是其发挥类雌激素作用、促进内源性神经再生作用机制之一。     

Neuroprotective Effect of the Marine-Derived Compound 11-Dehydrosinulariolide through DJ-1-Related Pathway in In Vitro and In Vivo Models of Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by tremor, rigidity, bradykinesia, and gait impairment. In a previous study, we found that the marine-derived compound 11-dehydrosinulariolide (11-de) upregulates the Akt/PI3K pathway to protect cells against 6-hydroxydopamine (6-OHDA)-mediated damage. In the present study, SH-SY5Y, zebrafish and rats were used to examine the therapeutic effect of 11-de. The results revealed the mechanism by which 11-de exerts its therapeutic effect: the compound increases cytosolic or mitochondrial DJ-1 expression, and then activates the downstream Akt/PI3K, p-CREB, and Nrf2/HO-1 pathways. Additionally, we found that 11-de could reverse the 6-OHDA-induced downregulation of total swimming distance in a zebrafish model of PD. Using a rat model of PD, we showed that a 6-OHDA-induced increase in the number of turns, and increased time spent by rats on the beam, could be reversed by 11-de treatment. Lastly, we showed that 6-OHDA-induced attenuation in tyrosine hydroxylase (TH), a dopaminergic neuronal marker, in zebrafish and rat models of PD could also be reversed by treatment with 11-de. Moreover, the patterns of DJ-1 expression observed in this study in the zebrafish and rat models of PD corroborated the trend noted in previous in vitro studies.     

Effect of CREB-shRNA on mitochondrial morphology and cell apoptosis in OGD/R-induced cortical neurons

AIM: To construct recombinant lentiviral vector with short hairpin RNA (shRNA) of CREB gene, and to investigate the effect of CREB gene silencing on mitochondrial morphology and cell apoptosis in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cortical neurons. METHODS: Three lentiviral vectors pLentiLox3.7 (PLL) inserted shRNA fragments targeting CREB gene were co-transfected with the packaging plasmids psPAX2 and pMD2.G to the 293T cells, and the virus particles, which was infected with the primary cortical neurons, was encapsulated. The protein expression of CREB was detected by Western blot. The mitochondrial morphology, cell apoptosis and the expression of Bcl-2 and Bax were evaluated by the methods of MitoTracker red, TUNEL and Western blot in OGD/R induced cortical neurons after CREB gene silencing. RESULTS: The pLL-CREB-shRNA1 was the most effective shRNA, which inhibited 80% CREB gene expression in the cortical neurons. The mitochondrial was appeared dot and fragment morphology in OGD/R induced cortical neurons with transfected pLL-CREB-shRNA1 plasmid. In addition, the expression of Bcl-2 was decreased, the expression of Bax, and the apoptosis of the neurons were increased by tranfected with pLL-CREB-shRNA1. CONCLUSION: CREB shRNA recombinant lentiviral vector specifically inhibits the expression of CREB gene. CREB gene silencing promotes the cell apoptosis and mitochondrial morphological changes in the cortical neurons induced by OGD/R.