PI分解酶

札幌酿酒有限公司和名古屋大学药学系池泽教授共同研制出世界上第一种磷脂酶C商品制剂。此酶可分解细胞膜的主要成分磷脂酰肌醇(PI)或甘油酸磷脂。这一新产品将用作研究活体膜的试剂。公司已通过日本主要的生化试剂研制企业,Funakoshi制药公司向国内外     

PI (α1) polymorphism in the Japanese: Confirmation of PI*M4 and description of new PI variants

PI phenotyping by separator isoelectric focusing (SIEF) was performed on a total of 1000 unrelated Japanese individuals from two different areas of Western Japan. The PI M1M4 subtype was observed together with the six common PI M subtypes. PI*M4 was confirmed to be present but rare in the Japanese. Several new PI variants were identified by comparison runs of each variant with previously reported genetic variants. The significance of treatment of serum with dithiothreitol (DTT) followed by iodacetic acid (IAC) in determination of PI variants is also described.     

Discovery of thiazolobenzoxepin PI3-kinase inhibitors that spare the PI3-kinase β isoform

A series of suitable five-membered heterocyclic alternatives to thiophenes within a thienobenzoxepin class of PI3-kinase (PI3K) inhibitors was discovered. Specific thiazolobenzoxepin 8-substitution was identified that increased selectivity over PI3Kβ. PI3Kβ-sparing compound 27 (PI3Kβ K_i,app/PI3Kα K_i,app = 57) demonstrated dose-dependent knockdown of pAKT, pPRAS40 and pS6RP in vivo as well as differential effects in an in vitro proliferation cell line screen compared to pan PI3K inhibitor GDC-0941. A new structure-based hypothesis for reducing inhibition of the PI3K β isoform while maintaining activity against α, δ and γ isoforms is presented.     

Insulin-Driven PI3K-AKT Signaling in the Hepatocyte Is Mediated by Redundant PI3Kα and PI3Kβ Activities and Is Promoted by RAS

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PI3K 抑制剂抗肿瘤临床研究进展

磷脂酰肌醇-3-激酶 (PI3K) 是一种胞内磷脂酰肌醇激酶,在介导细胞生长、发育、分裂、分化和凋亡等过程中发挥重要作用,因此 PI3K 抑制剂的开发已成为当前抗癌新药研究的热点之一。目前已有多个 PI3K 抑制剂进入临床研究阶段或已上市,其单用或与其他药物联 用的疗效和安全性有待进一步临床验证。综述 PI3K 抑制剂作为抗肿瘤药物的临床研究进展,为其进一步研究与应用提供参考。     

CoA Synthase is in complex with p85αPI3K and affects PI3K signaling pathway

The complex interplay between cellular signaling and metabolism in eukaryotic cells just start to emerge. Coenzyme A (CoA) and its derivatives play a key role in cell metabolism and also participate in regulatory processes. CoA Synthase (CoASy) is a mitochondria-associated enzyme which mediates two final stages of de novo CoA biosynthesis. Here, we report that CoASy is involved in signaling events in the cell and forms a functional complex with p85αPI3K in vivo. Importantly, observed interaction of endogenous CoASy and p85αPI3K is regulated in a growth factor dependent manner. Surprisingly, both catalytic p110α and regulatory p85α subunits of PI3K were detected in mitochondrial fraction where mitochondria-localized p85αPI3K was found in complex with CoASy. Unexpectedly, significant changes of PI3K signaling pathway activity were observed in experiments with siRNA-mediated CoASy knockdown pointing on the role of CoA biosynthetic pathway in signal transduction.     

PI法和Annexin V／PI法检测蓝舌病毒HbC3诱导人肝癌细胞的凋亡

利用流式细胞仪比较PI法和AnnexinV/PI法检测不同时间人肝癌细胞感染蓝舌病毒HbC3的凋亡率分析。结果:PI法在24h、36h、48h的凋亡率分别为10.8±3.05、21.7±6.28、28.3±10.6;AnnexinV/PI法的凋亡率分别为20.42±3.70、49.3±8.11、79.6±11.5。二种方法及不同时间感染病毒细胞的凋亡率之间有显著差异(P<0.01)。证明了AnnexinV/PI法能特异地、准确地检出早期凋亡的细胞、继发性坏死的细胞,BTV-HbC3诱导Hep-3B细胞凋亡是致肿瘤细胞病变、死亡的重要表现形式之一。     

PI法和Annexin V/PI法检测蓝舌病毒HbC3诱导人肝癌细胞的凋亡

利用流式细胞仪比较PI法和Annexin V/PI法检测不同时间人肝癌细胞感染蓝舌病毒HbC3的凋亡率分析.结果PI法在 24h、36h、48h的凋亡率分别为10.8 ±3.05、21.7±6.28、28.3±10.6;Annexin V/PI法的凋亡率分别为20.42±3.70、49.3±8.11、79.6±11.5.二种方法及不同时间感染病毒细胞的凋亡率之间有显著差异(P<0.01).证明了Annexin V/PI法能特异地、准确地检出早期凋亡的细胞、继发性坏死的细胞,BTV-HbC3诱导Hep-3B细胞凋亡是致肿瘤细胞病变、死亡的重要表现形式之一.     

DNA polymorphisms associated with a new α1-antitrypsin PI Q0 variant (PI Q0riedenburg)

Summary A new PI Q0 variant (PI Q0_riedenburg) is described; it is caused by a complete deletion of the ₁-antitrypsin (₁AT) gene. The deletion gives rise to four new restriction fragment length polymorphisms (RFLPs) detected with a genomic probe of the 5 region of the gene. Analysis of the RFLPs indicates that the deletion starts immediately upstream of exon Ic. The deletion extends into the 3 flanking region of the gene but does not include the ₁AT-related gene (the PIL gene), which is located 12 kb downstream of the ₁AT gene.     

Biophysical and Structural Characterization of Novel RAS-Binding Domains (RBDs) of PI3Kα and PI3Kγ

Phosphatidylinositol-3-kinases (PI3Ks) are lipid kinases that phosphorylate phosphatidylinositol 4,5-bisphosphate to generate a key lipid second messenger, phosphatidylinositol 3,4,5-bisphosphate. PI3Kα and PI3Kγ require activation by RAS proteins to stimulate signaling pathways that control cellular growth, differentiation, motility and survival. Intriguingly, RAS binding to PI3K isoforms likely differ, as RAS mutations have been identified that discriminate between PI3Kα and PI3Kγ, consistent with low sequence homology (23%) between their RAS binding domains (RBDs). As disruption of the RAS/PI3Kα interaction reduces tumor growth in mice with RAS- and epidermal growth factor receptor driven skin and lung cancers, compounds that interfere with this key interaction may prove useful as anti-cancer agents. However, a structure of PI3Kα bound to RAS is lacking, limiting drug discovery efforts. Expression of full-length PI3K isoforms in insect cells has resulted in low yield and variable activity, limiting biophysical and structural studies of RAS/PI3K interactions. This led us to generate the first RBDs from PI3Kα and PI3Kγ that can be expressed at high yield in bacteria and bind to RAS with similar affinity to full-length PI3K. We also solved a 2.31 Å X-ray crystal structure of the PI3Kα-RBD, which aligns well to full-length PI3Kα. Structural differences between the PI3Kα and PI3Kγ RBDs are consistent with differences in thermal stability and may underly differential RAS recognition and RAS-mediated PI3K activation. These high expression, functional PI3K RBDs will aid in interrogating RAS interactions and could aid in identifying inhibitors of this key interaction.     

GABARAP-mediated targeting of PI4K2A/PI4KIIα to autophagosomes regulates PtdIns4P-dependent autophagosome-lysosome fusion

For decades, phosphatidylinositol 4-phosphate (PtdIns4P) was considered primarily as a precursor in the synthesis of phosphatidylinositol(4,5)bisphosphate (PtdIns(4,5)P₂). More recently, specific functions for PtdIns4P itself have been identified, particularly in the regulation of intracellular membrane trafficking. PI4K2A/PI4KIIα (phosphatidylinositol 4-kinase type 2 α), one of the 4 enzymes that catalyze PtdIns4P production in mammalian cells, promotes vesicle formation from the trans-Golgi network (TGN) and endosomes. We recently identified a novel function for PI4K2A-derived PtdIns4P, as a facilitator of autophagosome-lysosome (A-L) fusion. We further showed that that this function requires the presence of the autophagic adaptor protein GABARAP (GABA[A] receptor-associated protein), which binds to PI4K2A and recruits it to autophagosomes. The mechanism whereby GABARAP-PI4K2A-PtdIns4P promotes A-L fusion remains to be defined. Based on other examples of phosphoinositide involvement in membrane trafficking, we speculate that it acts by recruiting elements of the membrane docking and fusion machinery.     

PI3K delta and PI3K gamma: partners in crime in inflammation in rheumatoid arthritis and beyond?

Dysregulated signal transduction in innate and adaptive immune cells is known to be associated with the development of various autoimmune and inflammatory diseases. Consequently, targeting intracellular signalling of the pro-inflammatory cytokine network heralds hope for the next generation of anti-inflammatory drugs. Phosphoinositide 3-kinases (PI3Ks) generate lipid-based second messengers that control an array of intracellular signalling pathways that are known to have important roles in leukocytes. In light of the recent progress in the development of selective PI3K inhibitors, and the beneficial effects of these inhibitors in models of acute and chronic inflammatory disorders, we discuss the therapeutic potential of blocking PI3K isoforms for the treatment of rheumatoid arthritis and other immune-mediated diseases.     

Molecular dynamics insights for PI3K-δ inhibition & structure guided identification of novel PI3K-δ inhibitors

Conjugated structure based and ligand based drug design techinques have been used previously to unearth putative binding ligands for kinase inhibition. PI3K-δ is a lipid kinase and it has been found abberant in diseases such as cancer,inflammation etc. Preliminarily, protein crystal structure analysis suggest avaibility of two crystal structures with varying degree of root mean square de throughtion in protein back bone and root mean square fluctuation in side chain geometry. Therefore, PI3K-δ crystal structure was selected based on charactristic reciever operating characterstic curve and % enrichment of actives analysis. Active site analysis through molecular dynamics simulations provided insights about four residues Ile910, Asp911, Met752, Lys755, which act as flap. These residues fecilitate ligand binding in a unique manner.Thereafter, a validated designed protocol has been used to screen asinex ligand database using molecular docking and binding energy calculations. Based on binding affinity & energy scores and interaction pattern analysis total top 50 ligands were selected for PI3K-δ inhibition studies. Moreover, two molecules ethyl 2-(2-((4-chloro-1-methyl-1H-pyrazole-3-carbonyl) oxy)acetamido) benzo[1]thiazole-6-carboxylate and 1,6,7-trimethyl-8-((tetrahydrofuran-2-yl) methyl)-1H-imidazo [1',2':1,5] pyrrolo[3,2-d]pyrimidine-2,4(3H,8H)-dione have been identified, which could be potential hits for PI3K-δ using insights provided by molecular modelling studies. The identified compunds were subjected to pan assay interference compound filter and were found to be compliant. Quantum mechanical calculations were perfromed for identified hits. The above strategy could be implemented as a strategy for rational drug design.

Communicated by Ramaswamy H. Sarma     

PI3K调控水稻种子萌发的机理研究

PI3K在植物的正常生长和胁迫应答过程中发挥着很重要的功能.在本文中,我们证实了在种子萌发过程中,PI3K促进了种子的萌发.通过RT-PCR的分析,我们发现,PI3K在整个过程中,伴随着吸胀时间的延长,表达量逐渐上升.而PI3K抑制剂的处理,证实了萌发过程中,PI3K促萌发的效应.DCF检测ROS的产生发现,在萌发的过程中,PBK促进了ROS的生成.PI3K产物PI3P亚细胞定位的分析发现,PI3P主要定位于膜结构区域.总之,本文借助于光学分子成像技术发现PI3K在种子萌发过程中的重要作用,提出PI3K通过调控ROS生成促进种子萌发的重要机理.     

第一届全国斑马鱼PI大会在武汉召开

第一届全国斑马鱼PI大会于2012年10月10-12日在中国科学院水生生物研究所召开。     

PI3K/Akt信号通路与肺纤维化

肺纤维化(pulmonary fibrosis)是进行性、致命性的疾病。其致病机制不明,治疗效果差。PI3K/Akt信号通路主要与细胞的生长、增殖、分化、凋亡及血管形成等有关。近年来,随着对PI3K/Akt信号通路的深入研究,发现其活化后可激活下游中的一些因子参与肺纤维化,且与其他通路协同作用促进肺纤维化的形成。因此该通路有可能成为治疗肺纤维化的新靶点。将PI3K/Akt信号通路参与肺纤维化形成的研究进展作一综述。