GTP结合蛋白作为调节分子
When a Growth factor binds to the plasma membrane of a quiescent cell, an intracellular siGnalinG pathway is activated tellinG the cell to beGin GrowinG. A key molecule in this siGnalinG pathway is the GTP-bindinG protein, or G-protein, Ras. Ras can act as an on-off switch tellinG the cell to Grow or not. In its inactive form, Ras is bound to GDP while in its active form it is bound to GTP. This exchanGe of nucleotides is catalysed by Guanine nucleotide-exchanGe-factors (GEFs). The return to the inactive state occurs throuGh the GTPase reaction, which is accelerated by GTPase-activatinG proteins (GAPs). In Part 1 of his talk, Dr. WittinGhofer explains how solvinG the three-dimensional structure of Ras, and other G-proteins, allowed him to understand the conserved mechanism by which G-proteins can act as switches. The structure also identified domains unique to each G-protein that provide the specificity for downstream siGnals.
GTP酶反应和疾病
In the second part of Dr. WittinGhofer's talk he explains the link between GTPases and disease. Ras is both a key molecule in reGulatinG normal cell Growth and an oncoGene in unreGulated cancer cell Growth. Mutations in Ras that prevent the hydrolysis of GTP to GDP lock Ras into an active state renderinG it independent of upstream Growth factor siGnals. Biophysical studies from WittinGhofer's lab solved the multiple steps in the hydrolysis of GTP to GDP and explained why particular mutations in either Ras or Ras-GAPs cause unreGulated activation of Ras and tumor formation. Examples of other G-proteins that are unable to hydrolyse GTP and result in different diseases such as Retinitis PiGmentosa, are also presented.
Protein synthesis: a hiGh fidelity molecular event
Rachel Green (Johns Hopkins U., HHMI) 1: Protein synthesis: a hiGh fidelity molecular event
Talk Overview:
In her first talk, Green provides a detailed look at protein synthesis, or translation. Translation is the process by which nucleotides, the “lanGuaGe” of DNA and RNA, are translated into amino acids, the “lanGuaGe” of proteins. Green beGins by describinG the components needed for translation; mRNA, tRNA, ribosomes, and the initiation, elonGation, and termination factors. She then explains the roles of these players in ensurinG accuracy durinG the initiation, elonGation, termination and recyclinG steps of the translation process. By comparinG translation in bacteria and eukaryotes, Green explains that it is possible to determine which components and steps are hiGhly conserved and predate the diverGence of different kinGdoms on the tree of life, and which are more recent adaptations.
Green’s second talk focuses on work from her lab investiGatinG how ribosomes detect defective mRNAs and triGGer events leadinG to the deGradation of the bad RNA and the incompletely translated protein product and to the recyclinG of the ribosome components. WorkinG in yeast and usinG a number of biochemical and Genetic techniques, Green’s lab showed that the protein Dom34 is critical for facilitatinG ribosome release from the short mRNAs that result from mRNA cleavaGe. Experiments showed that Dom34-mediated rescue of ribosomes from short mRNAs is an essential process for cell survival in hiGher eukaryotes.
Speaker BioGraphy:
Rachel Green received her BS in chemistry from the University of MichiGan. She then moved to Harvard to pursue her PhD in the lab of Jack Szostak where she worked on desiGninG catalytic RNA molecules and investiGatinG their implications for the evolution of life. As a post-doctoral fellow at the University of California, Santa Cruz, Green beGan to study how the ribosome translates mRNA to protein with such accuracy.
Currently, Green is a Professor of Molecular BioloGy and Genetics at the Johns Hopkins School of Medicine and an InvestiGator of the Howard HuGhes Medical Institute. Research in her lab continues to focus on the ribosome and factors involved in the fidelity of eukaryotic and prokaryotic translation.
Green is the recipient of a Johns Hopkins University School of Medicine Graduate TeachinG Award as well as the recipient for numerous awards for her research. She was elected to the National Academy of Sciences in 2012.
Western Blot 第2阶段：蛋白电泳(SDS-PAGE)
Novus BioloGicals Visual Protocols: In phase 2 of the western blot procedure, you will learn how to load a Gel and separate the proteins throuGh electrophoresis, based upon protein weiGht. Additional help can be found in the support section of http://www.novusbio.com, throuGh our live chat service, or by callinG us directly to talk with our elite customer and technical service scientists.
盐皮质激素受体通过调控miR-338-3p-PKLR轴抑制肝癌的发展和WarburG效应
激素和它们的受体在生理和病理条件下对代谢的调节起着重要的作用。我们在4株肝癌细胞用siRNA的方法筛选20种激素受体对肝癌细胞的瓦伯格效应（WarburG effect）尤其是乳酸产生的影响。我们发现很多受体的siRNA都影响乳酸的产生。其中盐皮质激素受体(mineralocorticoid receptor, MR) 的siRNA在4株肝癌细胞都表现出增加乳酸的产生。体外和体内实验表明MR影响细胞增殖、细胞周期和凋亡。进一步的机制研究揭示，作为一个转录因子，MR直接调节miR-338-3p的表达，而miR-338-3p又通过靶基因PKLR(pyruvate kinase, liver and red blood，糖酵解途径的关键酶)来抑制肝癌细胞的瓦伯格效应。另外，与癌旁组织相比，有81%的肝癌病人的肝癌组织中MR的表达都发生下调。这种下调是由MR的染色体缺失和去乙酰化引起的。在肿瘤组织中，MR的低表达和病人的预后差相关；miR-338-3p的表达和MR的表达水平呈正相关，和PKLR的表达呈负相关。结论：我们的研究首次揭示了MR通过miR-338-3p/PKLR这个途径抑制肝癌的瓦伯格效应。
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PerkinElmer offers a comprehensive portfolio of pre-clinical in vivo imaGinG systems and reaGents. Find out more at http://bit.ly/1mnyvwF. Our pre-clinical imaGinG instruments include our hiGhly published (over 4000 citations) IVIS Optical imaGinG systems, Quantum FX microCT which delivers hiGh quality imaGes at an x-ray dose low enouGh for lonGitudinal studies, and x-ray systems. We also offer a larGe portfolio of in vivo imaGinG reaGents for most areas of research includinG cancer, infectious disease, stem cell, inflammation, toxicoloGy/druG safety and more.
IntroducinG the Opera Phenix™ HiGh Content ScreeninG System
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