葡萄糖感应器及其AMPK活性和细胞代谢状态的调控机理

葡萄糖是细胞的主要能量来源,它通过糖酵解和/或氧化代谢产生ATP。葡萄糖水平下降将激活AMP活化蛋白激酶(AMP-activated protein kinase-AMPK),数十年来,人们一直认为这是由于AMP或ADP的上升,或者说能量水平的下降引起的。厦门大学生命科学学院林圣彩研究团队与英国Dundee大学D.Grahame Hardie团队合作报道了一种通过感知胞内葡萄糖代谢中间物果糖-1,6-二磷酸(FBP)的下降来触发AMPK活化的机制:FBP水平下降,便不再占据其催化酶——醛缩酶(aldolase)上的催化位点,后者直接改变了溶酶体膜上的质子泵v-ATPase和与其相结合的\"Ragulator\"的构象,进而让携带有能磷酸化并激活AMPK的上游激酶LKB1的AXIN蛋白质转移到溶酶体膜表面,在此形成了能激活AMPK的复合体(该复合体也是由林圣彩实验室发现并鉴定-Cell Metabolism,2013,2014),从而激活AMPK,同时抑制了促进细胞进行生物合成和生长的激酶-mTORC1。重要的是,他们从中也颠覆性地发现细胞能量水平在葡萄糖水平急速下降期间仍保持不变,且AMPK上的AMP结合位点对于此时AMPK的活化不是必需的。该研究不仅发现了醛缩酶这一糖酵解酶的新功能:调控AMPK的葡萄糖感受器,还深刻地揭示了葡萄糖的本质:既是能量和物质来源,也是直接调控细胞生物合成和生长状态的信号,对多种代谢型疾病的发生、癌症与代谢关系的认知与治疗、卡路里限制与健康长寿等的认知具有重大意义。相关研究论文在2017年8月3日发表于《自然》[NATURE,548(7665):112-116,August 2017]

RXRα acts as a carrier for TR3 nuclear export in a 9-cis retinoic acid-dependent manner in gastric cancer cells

Retinoid X receptor (RXR) plays a crucial role in the cross talk between retinoid receptors and other hormone receptors including the orphan receptor TR3, forming different heterodimers that transduce diverse steroid/thyroid hormone signaling. Here we show that RXRalpha exhibits nucleocytoplasmic shuttling in MGC80-3 gastric cancer cells and that RXRalpha, shuttling is energy-dependent through a nuclear pore complex (NPC)mediated pathway for its import and an intact DNA binding domain-mediated pathway for its export. In the presence of its ligand 9-cis retinoic acid, RXRalpha was almost exclusively located in the cytoplasm. More importantly, we also show that RXRalpha. acts as a carrier to assist translocation of TR3, which plays an important role in apoptosis. Both RXRalpha and TR3 colocalized in the nucleus; however, upon stimulation by 9-cis retinoic acid they cotranslocated to the cytoplasm and then localized in the mitochondria. TR3 export depends on RXRalpha as in living cells GFP-TR3 alone did not result in export from the nucleus even in the presence of 9-cis retinoic acid, whereas GFP-TR3 cotransfected with RXRalpha was exported out of the nucleus in response to 9-cis retinoic acid. Moreover, specific reduction of RXRalpha levels caused by anti-sense RXRalpha abolished TR3 nuclear export. In contrast, specific knockdown of TR3 by antisense-TR3 or TR3-siRNA did not affect RXRalpha shuttling. These results indicate that RXRalpha is responsible for TR3 nucleocytoplasmic translocation, which is facilitated by the RXRalpha ligand 9-cis retinoic acid. In addition, mitochondrial TR3, but not RXRalpha was critical for apoptosis, as TR3 mutants that were distributed in the mitochondria induced apoptosis in the presence or absence of 9-cis retinoic acid. These data reveal a novel aspect of RXRalpha function, in which it acts as a carrier for nucleocytoplasmic translocation of orphan receptors

Revealing a steroid receptor ligand as a unique PPARγ agonist

过氧化物酶体增殖体激活受体γ（PPARγ）是核受体家族成员之一，它能够调节机体新陈代谢平衡，是国际上研发治疗糖尿病等代谢类疾病及抗癌药物的热门药物分子靶标。然而，许多副作用局限了这些配体药物的临床使用，如噻唑烷类（TZDs）PPARγ配体药物会导致体重增加、水肿、心力衰竭与肝中毒等。本课题通过研究前期筛选到的化合物米非司酮（RU-486），发现该化合物是一种新型PPARγ特异性类固醇激动剂。通过对PPARγ/RU-486复合体进行结晶、X射线衍射、对收集的衍射数据进行解析，我们从分子水平上揭示了这一独特的RU-486在PPARγ配体结合域内的特殊结合模型，从原子水平上解释了RU-486如何通过...Peroxisome proliferator activated receptor gamma (PPARγ) is a member of nuclear receptor family, which regulates metabolic homeostasis and is a hot molecular target for anti-diabetic and anti-cancer drugs research of the world. We report here the identification of a steroid receptor ligand, RU-486, as an unexpected PPARγ agonist by High through put drug screening. We constructed the crystal of PPA...学位：理学硕士院系专业：生命科学学院生物医学科学系_生物化学与分子生物学学号：2172008115264

AMPK:不仅能感应细胞的能量状态还能感应葡萄糖

文章简介腺嘌呤核苷酸水平的改变,即AMP/ATP和ADP/ATP比值的上升是细胞能量状态下降的信号。众所周知,哺乳动物的AMPK会随细胞能量水平的下降而激活。这篇综述回顾了近来关于细胞的低能量状态如何激活AMPK的研究成果,同时还探讨了最近关于国家重点研发计划;;\n国家自然科学基金委项目的支

Frequency and distribution of AP-1 sites in the human genome

The AP-1-binding sequences are promoter/enhancer elements that play an essential role in the induction of many genes in mammalian cells; however, the number of genes containing AP-1 sites remains unknown. In order to better address the overall effect of AP-1 on expression of genes encoded by the entire genome, a genome-wide analysis of the frequency and distribution of AP-1 sites would be useful; yet to date, no such analysis of AP-1 sites or any other promoter/enhancer elements has been performed. We present here our study of the consensus AP-1 site and two single-bp variants showing that the frequency of AP-1 sites in promoter regions is significantly lower than their average rate of occurrence in the whole genomic sequence, as well as the frequency of a random heptanucleotide suggesting that nature has selected for a decrease in the frequency of AP-1 sites in the regulatory regions of genes. In addition, genes containing multiple AP-1 sites are more prevalent than those containing only one copy of an AP-1 site, which again may have evolved to allow for greater signal amplification or integration in the regulation of AP-1 target genes. However, the number of AP-1-regulated genes identified in various studies is far smaller than the number of genes containing potential AP-1 sites, indicating that not all AP-1 sites are activated in a given cell under a given condition, and is consistent with the prediction by others that cellular context determines which AP-1 sites are targeted by AP-1

p38MAPK induces apoptosis of glioma cell

目的　研究 p38MAPK基因转染大鼠胶质瘤细胞系C6后对其生物学特性的影响 .方法　利用脂质体介导法将p38MAPK基因导入大鼠胶质瘤细胞系 C6中 ,用免疫细胞化学染色检测其在细胞转染前后的表达情况 ,用 HE染色、流式细胞仪等方法研究其对细胞形态、粘着状况和生长周期的影响 .结果　转染 p CMV5 - p38MAPK质粒组 p38MAPK蛋白表达阳性 ,细胞形态发生变化 ,贴壁性降低 ,出现大量凋亡细胞 .结论　转染 p38MAPK基因可诱导胶质瘤细胞凋亡 【英文摘要】 AIM To study the effect of p38MAPK transfection on the biological characteristics of glioma cell C6. METHODS p38MAPK was transfected into glioma cell C6 by lipofectin. Expression of p38MAPK was detected by immunocytochemistry. HE staining and flow cytometry were adopted to measure the cell morphology, adhesion and cell cycle. RESULTS p38MAPK was expressed in transfected glioma cells, with cell biological characteristics changing and apoptotic cells emerging. CONCLUSION Apoptosis of glioma cell could be ...高等学校骨干教师计划资

Determinants that control the specific interactions between TAB1 and p38α

Previous studies have revealed that transforming growth factor-beta-activated protein kinase 1 (TAB1) interacts with p38 alpha and induces p38 alpha autophosphorylation. Here, we examine the sequence requirements in TAB1 and p38 alpha that drive their interaction. Deletion and point mutations in TAB1 reveal that a proline residue in the C terminus of TAB1 (Pro412) is necessary for its interaction with p38 alpha. Furthermore, a cryptic D-domain-like docking site was identified adjacent to the N terminus of Pro412, putting Pro412 in the (phi(B)+3 position of the docking site. Through mutational analysis, we found that the previously identified hydrophobic docking groove in p38 alpha is involved in this interaction, whereas the CD domain and ED domain are not. Furthermore, chimeric analysis with p38 beta (which does not bind to TAB1) revealed a previously unidentified locus of p38 alpha comprising Thr218 and Ile275 that is essential for specific binding of p38 alpha to TAB1. Converting either of these residues to the corresponding amino acid of p380 abolishes p38 alpha interaction with TAB1. These p38a mutants still can be fully activated by p38 alpha upstream activating kinase mitogen-activated protein kinase kinase 6, but their basal activity and activation in response to some extracellular stimuli are reduced. Adjacent to Thr218 and Ile275 is a site where large conformational changes occur in the presence of docking-site peptides derived from p38 alpha substrates and activators. This suggests that TAB1-induced autophosphorylation of p38 alpha results from conformational changes that are similar but unique to those seen in p38 alpha interactions with its substrates and activating kinases