Wong S L Alan, Chen Yiwei, Chan Chak Ming, Chan C S Michael, Chan Paul K S, Chui Y L, Fung Kwok Pui, Waye Mary M Y, Tsui Stephen K W, Chan H Y Edwin
Laboratory of Drosophila Research, The Chinese University of Hong Kong, Shatin, NT, China.
Biochem Biophys Res Commun. 2005 Nov 18;337(2):720-9. doi: 10.1016/j.bbrc.2005.09.098. Epub 2005 Sep 26.
The Severe Acute Respiratory Syndrome-Coronavirus (SARS-CoV) 3a locus encodes a 274 a.a. novel protein, and its expression has been confirmed in SARS patients. To study functional roles of 3a, we established a transgenic fly model for the SARS-CoV 3a gene. Misexpression of 3a in Drosophila caused a dominant rough eye phenotype. Using a specific monoclonal antibody, we demonstrated that the 3a protein displayed a punctate cytoplasmic localization in Drosophila as in SARS-CoV-infected cells. We provide genetic evidence to support that 3a is functionally related to clathrin-mediated endocytosis. We further found that 3a misexpression induces apoptosis, which could be modulated by cellular cytochrome c levels and caspase activity. From a forward genetic screen, 78 dominant 3a modifying loci were recovered and the identity of these modifiers revealed that the severity of the 3a-induced rough eye phenotype depends on multiple cellular processes including gene transcriptional regulation.
严重急性呼吸综合征冠状病毒（SARS-CoV）的3a基因座编码一种含274个氨基酸的新型蛋白质，其表达已在SARS患者中得到证实。为了研究3a的功能作用，我们建立了一个针对SARS-CoV 3a基因的转基因果蝇模型。3a在果蝇中的错误表达导致显性粗糙眼表型。使用特异性单克隆抗体，我们证明3a蛋白在果蝇中呈现点状细胞质定位，如同在感染SARS-CoV的细胞中一样。我们提供了遗传学证据来支持3a在功能上与网格蛋白介导的内吞作用相关。我们进一步发现3a的错误表达诱导细胞凋亡，这可由细胞细胞色素c水平和半胱天冬酶活性调节。通过正向遗传学筛选，鉴定出78个显性3a修饰基因座，这些修饰因子的特性表明3a诱导的粗糙眼表型的严重程度取决于包括基因转录调控在内的多个细胞过程。
