在caspase-9和Smac/DIABLO中保存的XIAP相互作用动机调节了caspase活动和亡
S M Srinivasula1, R Hegde, A Saleh
1Center for Apoptosis Research and the Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Nature
|March 10, 2001
概括
与X相关的亡抑制蛋白 (XIAP) 与caspase-9结合,从而抑制了亡. 结合XIAP的smac蛋白破坏了这种相互作用,通过释放caspase-9活性来促进细胞灭绝. 这揭示了编程细胞死亡中的关键调节机制.
科学领域:
- 细胞生物学 细胞生物学
- 分子生物学分子生物学
- 生物化学 生物化学
背景情况:
- 与X相关的亡抑制蛋白 (XIAP) 是亡的关键调节者,抑制了亡酶的活性.
- 斯马克 (DIABLO) 对抗XIAP,通过缓解卡斯巴酶抑制来促进亡.
研究的目的:
- 阐明XIAP与caspase-9.9相互作用并抑制的分子机制.
- 调查Smac与XIAP结合如何影响caspase-9活性和亡.
主要方法:
- 在Asp315.15进行位点定向的突变发生,以废止procaspase-9处理.
- 卡斯巴-9链接的删除突变发生.
- 对XIAP-caspase-9复合体形成和抑制试验的分析.
主要成果:
- XIAP与活跃的caspase-9-Apaf-1复合体内的caspase-9链接的加工氨基末端结合.
- 阻止链接器处理或删除链接器的突变取消了XIAP结合和抑制.
- -9链接和Smac与XIAP的BIR3域结合是相互排斥的,Smac破坏了XIAP-链接器相互作用.
结论:
- 通过直接与其加工的链接结合,XIAP抑制了酶-9的活性.
- 通过从XIAP的BIR3域中竞争性地取代caspase-9链接器,Smac增强了caspase-9活性和细胞亡.
- 这确定了一种涉及与XIAP对抗相互作用的保存机制,该机制调节了亡.
相关概念视频
Apoptosis
Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
Caspases
Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
The Extrinsic Apoptotic Pathway
The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
The Intrinsic Apoptotic Pathway
Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
Phagocytosis of Apoptotic Cells
Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or immature dendritic cells. Non-professional phagocytes such as epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
The JAK-STAT Signaling Pathway
Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as SH2...


