Shiohara Masaaki, Taniguchi Shun'ichiro, Masumoto Junya, Yasui Kozo, Koike Kenichi, Komiyama Atsushi, Sagara Junji
Department of Pediatrics, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan.
Biochem Biophys Res Commun. 2002 May 24;293(5):1314-8. doi: 10.1016/S0006-291X(02)00384-4.
ASC is an adaptor protein that is composed of two protein-protein interaction domains, a PYRIN domain (PYD), and a caspase-recruitment domain (CARD). Recently, ASC was identified as a binding partner of pyrin, which is the product of MEFV, a gene causing familial Mediterranean fever (FMF). Mutations in MEFV result in defects in control of neutrophil-mediated inflammation. Thus we focused on the expression of ASC in neutrophils. Immunohistochemical study showed that ASC is increased in neutrophils in severe inflammatory sites of gangrenous appendicitis. We, then, tested whether proinflammatory mediators induce ASC using peripheral blood neutrophils in vitro. ASC expression was transiently up-regulated by IL-1alpha, IL-1beta, IFN-alpha, IFN-gamma, TNFalpha, and LPS. ASC was also increased by incubation with either anti-Fas antibody or recombinant soluble Fas ligand. The Fas-mediated induction of ASC was inhibited by a general caspase inhibitor, z-VAD-fmk, and an immunocytochemical study showed that ASC was increased in neutrophils exhibiting characteristic phenotypes for apoptosis. These findings suggest that up-regulation of ASC is closely associated with inflammation and apoptosis in neutrophils.
ASC是一种衔接蛋白，由两个蛋白质-蛋白质相互作用结构域组成，即一个吡啉结构域（PYD）和一个半胱天冬酶募集结构域（CARD）。最近，ASC被鉴定为吡啉的结合伴侣，吡啉是MEFV基因的产物，MEFV基因可导致家族性地中海热（FMF）。MEFV基因突变导致中性粒细胞介导的炎症控制缺陷。因此，我们重点研究了ASC在中性粒细胞中的表达。免疫组织化学研究表明，在坏疽性阑尾炎严重炎症部位的中性粒细胞中ASC增加。然后，我们在体外使用外周血中性粒细胞测试促炎介质是否诱导ASC。IL-1α、IL-1β、IFN-α、IFN-γ、TNFα和LPS可使ASC表达瞬时上调。用抗Fas抗体或重组可溶性Fas配体孵育也可使ASC增加。Fas介导的ASC诱导被通用半胱天冬酶抑制剂z-VAD-fmk抑制，免疫细胞化学研究表明，在表现出凋亡特征性表型的中性粒细胞中ASC增加。这些发现表明，ASC的上调与中性粒细胞中的炎症和凋亡密切相关。
