Notch途径与宫颈癌细胞系的增殖调控

近年来在许多肿瘤细胞系中发现Notch基因的表达失常,失控的Notch信号对维持肿瘤细胞表型性起着重要作用。在宫颈癌细胞中,异常上调的Notch信号通路由人乳头瘤病毒(HPV)相关蛋白“E6/7”介导,并能与之发生协同作用维持肿瘤的生长及异型性,另一方面,激活的Notch1又能通过抑制Fos蛋白家族进而抑制“E6/7”的表达,并能通过抑制E47蛋白引起细胞增殖抑制。结合对不同时期宫颈癌细胞的研究结果,目前认为低水平的Notch1表达对维持发生癌变的角质细胞的生存相当重要,过多或过少的Notch1信号都会对细胞增殖造成负面影响。     

Modulation of Ca2+ signals by phosphatidylinositol-linked novel D1 dopamine receptor in hippocampal neurons

Recent evidence indicates the existence of a putative novel phosphatidylinositol-linked D1 dopamine receptor in brain that mediates phosphatidylinositol hydrolysis via activation of phospholipase Cbeta. The present work was designed to characterize the Ca(2+) signals regulated by this phosphatidylinositol-linked D(1) dopamine receptor in primary cultures of hippocampal neurons. The results indicated that stimulation of phosphatidylinositol-linked D1 dopamine receptor by its newly identified selective agonist SKF83959 induced a long-lasting increase in basal [Ca(2+)](i) in a time- and dose-dependent manner. Stimulation was observable at 0.1 microm and reached the maximal effect at 30 microm. The [Ca(2+)](i) increase induced by 1 microm SKF83959 reached a plateau in 5 +/- 2.13 min, an average 96 +/- 5.6% increase over control. The sustained elevation of [Ca(2+)](i) was due to both intracellular calcium release and calcium influx. The initial component of Ca(2+) increase through release from intracellular stores was necessary for triggering the late component of Ca(2+) rise through influx. We further demonstrated that activation of phospholipase Cbeta/inositol triphosphate was responsible for SKF83959-induced Ca(2+) release from intracellular stores. Moreover, inhibition of voltage-operated calcium channel or NMDA receptor-gated calcium channel strongly attenuated SKF83959-induced Ca(2+) influx, indicating that both voltage-operated calcium channel and NMDA receptor contribute to phosphatidylinositol-linked D(1) receptor regulation of [Ca(2+)](i).     

Blocking of N-acetylglucosaminyltransferase V induces cellular endoplasmic reticulum stress in human hepatocarcinoma 7,721 cells

N-acetylglucosaminyltransferase V （GnT-V） is an important tumorigenesis and metastasis-associated enzyme. To study its biofunction, the GnT-V stably suppressed cell line （GnT-V-AS/7721） was constructed from 7721 hepatocarcinoma cells in previous study. In this study, cDNA array gene expression profiles were compared between GnT-V-AS/7721 and parental 7721 cells. The data indicated that GnT-V-AS/7721 showed a characteristic expression pattern consistent with the ER stress. The molecular mechanism of the ER stress was explored in GnT-V-AS/7721 by the analysis on key molecules in both two unfolded protein response （UPR） pathways. For ATF6 and Irel/XBP-1 pathway, it was evidenced by the up-regulation of BIP at mRNA and protein level, and the appearance of the spliced form ofXBP-1. As for PERK/eIF2α pathway, the activation of ER eIF2α kinase PERK was observed. To confirm the results from GriT-V-AS/7721 cells, the key molecules in the UPR were examined again in 7721 cells interfered with the GnT-V by the specific RNAi treatment. The results were similar with those from GnT-V-AS/7721, indicating that blocking of GnT-V can specifically activate ER stress in 7721 cells. Rate of 3H-Man incorporation corrected with rate of 3H-Leu incorporation in GnT-V-AS/7721 was down-regulated greatly compared with the control, which demonstrated the deficient function of the enzyme synthesizing N-glycans after GnT-V blocking. Moreover, the faster migrating form of chaperone GRP94 associated with the underglycosylation, and the extensively changed N-glycans structures of intracellular glycoproteins were also detected in GnT-V-AS/7721. These results supported the mechanism that blocking of GnT-V expression impaired functions of chaperones and N-glycan-synthesizing enzymes, which caused UPR in vivo.     

新疆分离细菌的提取物对λ噬菌体紫外诱导的抑制作用

本研究从我国夏季高温、强辐射的新疆塔里木地区采集样品,进行了细菌的分离、纯化及分类鉴定。用丙酮萃取法抽提39个分离菌株的培养产物,通过高效液相色谱和紫外-可见吸收光谱分析其主要组分;利用λ噬菌体紫外诱导系统研究抽提物清除自由基的能力。高效液相色谱和紫外-可见吸收光谱分析的结果表明:多数分离菌株丙酮提取物的主要组分为类胡萝卜素物质。λ噬菌体紫外诱导系统抑制实验结果表明:29个菌株的丙酮提取物对λ噬菌体的紫外诱导具有不同程度的抑制作用,抑制率最高达81%。不同菌株之间的比较试验显示不同属细菌的丙酮提取物对λ噬菌体紫外诱导系统的抑制效果存在很大差异,其中以Methylobacterium的抑制作用最强;不同颜色菌株提取物的抑制效果也出现较大差异;Koanria中不同颜色菌株的抑制效果也有类似结果。本文为类胡萝卜素可能是该类细菌具有抗辐射能力的内因之一提供了直接证据。同时,也证实了λ噬菌体紫外诱导系统是一种很好的探讨细菌抗辐射机理的研究模型。     

肾上腺髓质素在正常大鼠脑中的分布一免疫组化及原位杂交分析

目的验证大鼠脑内是否存在ADM及其mRNA。方法取10只健康雄性SD大鼠,体重200-250g,应用免疫组织化学法和原位杂交组织化学法检测正常大鼠脑内ADM及其mRNA的表达情况。结果在大鼠脑内ADM及其mRNA阳性细胞主要表达在大脑皮质、海马结构、齿状回、丘脑、室旁组织、脉络丛、室管膜细胞、基底节、血管内皮细胞,其中脉络丛、室旁组织、丘脑为高表达区,其次为大脑皮质、海马。在大鼠大脑内ADMmRNA的表达与ADM阳性细胞的表达相一致。结论ADM及其mRNA在大脑内广泛表达,提示ADM在中枢神经系统内具有重要的作用。     

荒漠生态系统对大气CO2浓度升高响应的干湿年差异

利用一个基于详细生理学过程的生态系统模型PALS-FT,通过模拟实验分析了美国亚利桑那州(Arizona)首府凤凰城(Phoenix)市西郊的Larreatridentata荒漠生态系统在干湿年份(1988-2002年)对大气CO2浓度升高响应的差别。结果表明,生态系统地上净初级生产力(ANPP)和土壤有机质年累积速率(SOM)均随大气CO2浓度升高而呈非线性(湿年)或线性(正常年和干年)增加;所有年份的土壤N含量(Nsoil)则呈非线性显著下降。ANPP与SOM的绝对变化量总是湿年大于正常年和干年,相对变化量则与所分析的CO2处理水平有关;Nsoil的绝对变化量和相对变化量均为湿年大于正常年和干年。不同功能型的植物ANPP对大气CO2浓度升高的绝对变化量均为湿年大于正常年和干年;相对变化量则因具体植物功能型而异,灌木和亚灌木为干年大于正常年和湿年,一年生C3和C4草本均为湿年大于正常年和干年。因此,无论是生态系统水平还是植物功能型(或物种)水平,荒漠生态系统对未来大气CO2浓度升高的响应都将受降水格局的显著影响。     

FMRFamide-Like Peptides (FLPs) Enhance Voltage-Gated Calcium Currents to Elicit Muscle Contraction in the Human Parasite Schistosoma mansoni

Schistosomes are amongst the most important and neglected pathogens in the world, and schistosomiasis control relies almost exclusively on a single drug. The neuromuscular system of schistosomes is fertile ground for therapeutic intervention, yet the details of physiological events involved in neuromuscular function remain largely unknown. Short amidated neuropeptides, FMRFamide-like peptides (FLPs), are distributed abundantly throughout the nervous system of every flatworm examined and they produce potent myoexcitation. Our goal here was to determine the mechanism by which FLPs elicit contractions of schistosome muscle fibers. Contraction studies showed that the FLP Tyr-Ile-Arg-Phe-amide (YIRFamide) contracts the muscle fibers through a mechanism that requires Ca²⁺ influx through sarcolemmal voltage operated Ca²⁺ channels (VOCCs), as the contractions are inhibited by classical VOCC blockers nicardipine, verapamil and methoxyverapamil. Whole-cell patch-clamp experiments revealed that inward currents through VOCCs are significantly and reversibly enhanced by the application of 1 µM YIRFamide; the sustained inward currents were increased to 190% of controls and the peak currents were increased to 180%. In order to examine the biochemical link between the FLP receptor and the VOCCs, PKC inhibitors calphostin C, RO 31–8220 and chelerythrine were tested and all produced concentration dependent block of the contractions elicited by 1 µM YIRFamide. Taken together, the data show that FLPs elicit contractions by enhancing Ca²⁺ influx through VOCC currents using a PKC-dependent pathway.     

Association of the MC4R V103I Polymorphism With Obesity: A Chinese Case–control Study and Meta‐analysis in 55,195 Individuals

Recently, large‐scaled studies suggested a negative association of the infrequent allele of the melanocortin‐4 receptor (MC4R) V103I polymorphism with obesity. We conducted a Chinese case–control study, meta‐analysis in East Asians and in all populations, in order to further assess the association between the V103I polymorphism and reduced body weight and to explore whether the association varies among different ethnic groups. We conducted a case–control study to analyze this polymorphism in 2,012 children of two independent study groups from Beijing, China, no association was found between the V103I polymorphism and obesity or obesity‐related phenotypes (P > 0.10). In the meta‐analysis of 3,526 individuals from six East Asian studies, I103 carriers had a 31% lower risk for obesity (odds ratio (OR) = 0.69, 95% confidence interval (CI): 0.50–0.94, P = 0.02). Subsequently, we performed a large meta‐analysis of the six East Asian studies and 31 studies of other ethnic groups, involving 55,195 individuals with 19,822 obese cases and 35,373 nonobese controls. In total, the individuals with I103 allele had a 21% lower risk for obesity (OR = 0.79, 95% CI: 0.71–0.88, P < 0.0001). In conclusion, this study confirmed and extended the previous findings, suggesting the MC4R V103I polymorphism is negatively associated with human obesity. It provides significant evidence for the association in East Asian populations. Further large‐scaled studies in East Asian populations are needed to validate the association.