Chao Kinlin L, Kulakova Liudmila, Herzberg Osnat
Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850.
Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850;
Proc Natl Acad Sci U S A. 2017 Feb 14;114(7):E1128-E1137. doi: 10.1073/pnas.1616783114. Epub 2017 Feb 1.
The exact function of human gasdermin-B (GSDMB), which regulates differentiation and growth of epithelial cells, is yet to be elucidated. In human epidermal growth factor receptor 2 (HER2)-positive breast cancer, gene amplification and protein overexpression indicate a poor response to HER2-targeted therapy. Genome-wide association studies revealed a correlation between SNPs and an increased susceptibility to Crohn's disease, ulcerative colitis, and asthma. The N- and C-terminal domains of all gasdermins possess lipid-binding and regulatory activities, respectively. Inflammatory caspases cleave gasdermin-D in the interdomain linker but not GSDMB. The cleaved N-terminal domain binds phosphoinositides and cardiolipin, forms membrane-disrupting pores, and executes pyroptosis. We show that both full-length GSDMB and the N-terminal domain bind to nitrocellulose membranes immobilized with phosphoinositides or sulfatide, but not with cardiolipin. In addition, the GSDMB N-terminal domain binds liposomes containing sulfatide. The crystal structure of the GSDMB C-terminal domain reveals the structural impact of the amino acids encoded by SNPs that are linked to asthma and inflammatory bowel disease (IBD). A loop that carries the polymorphism amino acids corresponding to healthy individuals (Gly299:Pro306) exhibits high conformational flexibility, whereas the loop carrying amino acids found in individuals with increased disease risk (Arg299:Ser306) exhibits a well-defined conformation and higher positive surface charge. Apoptotic executioner caspase-3, -6, and -7, but not the inflammatory caspases, cleave GSDMB at DNVD within the N-terminal domain. Selective sulfatide binding may indicate possible function for GSDMB in the cellular sulfatide transport.
人类gasdermin-B（GSDMB）可调节上皮细胞的分化和生长，其确切功能尚待阐明。在人表皮生长因子受体2（HER2）阳性乳腺癌中，基因扩增和蛋白过表达表明对HER2靶向治疗反应不佳。全基因组关联研究揭示了单核苷酸多态性（SNP）与克罗恩病、溃疡性结肠炎和哮喘易感性增加之间的相关性。所有gasdermin的N端和C端结构域分别具有脂质结合和调节活性。炎性半胱天冬酶在结构域间连接区切割gasdermin-D，但不切割GSDMB。切割后的N端结构域结合磷酸肌醇和心磷脂，形成破坏膜的孔，并引发细胞焦亡。我们发现全长GSDMB和N端结构域均能结合固定有磷酸肌醇或硫脂的硝酸纤维素膜，但不能结合心磷脂。此外，GSDMB N端结构域能结合含有硫脂的脂质体。GSDMB C端结构域的晶体结构揭示了与哮喘和炎症性肠病（IBD）相关的SNP所编码氨基酸的结构影响。携带对应健康个体的多态性氨基酸（Gly299:Pro306）的环表现出高构象灵活性，而携带疾病风险增加个体中发现的氨基酸的环表现出明确的构象和更高的正表面电荷。凋亡执行半胱天冬酶-3、-6和-7而非炎性半胱天冬酶在N端结构域的DNVD处切割GSDMB。选择性硫脂结合可能表明GSDMB在细胞硫脂转运中具有潜在功能。
