Miranda L, Wolf J, Pichuantes S, Duke R, Franzusoff A
Department of Cellular and Structural Biology, Molecular Biology Program, University of Colorado Cancer Center, Denver 80262, USA.
Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):7695-700. doi: 10.1073/pnas.93.15.7695.
Production of infectious HIV-1 virions is dependent on the processing of envelope glycoprotein gp160 by a host cell protease. The protease in human CD4+ T lymphocytes has not been unequivocally identified, yet members of the family of mammalian subtilisin-like protein convertases (SPCs), which are soluble or membrane-bound proteases of the secretory pathway, best fulfill the criteria. These proteases are required for proprotein maturation and cleave at paired basic amino acid motifs in numerous cellular and viral glycoprotein precursors, both in vivo and in vitro. To identify the gp160 processing protease, we have used reverse transcription-PCR and Northern blot analyses to ascertain the spectrum of SPC proteases in human CD4+ T cells. We have cloned novel members of the SPC family, known as the human PC6 genes. Two isoforms of the hPC6 protease are expressed in human T cells, hPC6A and the larger hPC6B. The patterns of SPC gene expression in human T cells has been compared with the furin-defective LoVo cell line, both of which are competent in the production of infectious HIV virions. This comparison led to the conclusion that the hPC6 gene products are the most likely candidates for the host cell protease responsible for HIV-1 gp160 processing in human CD4+ T cells.
传染性HIV-1病毒粒子的产生依赖于宿主细胞蛋白酶对包膜糖蛋白gp160的加工处理。人类CD4+ T淋巴细胞中的蛋白酶尚未得到明确鉴定，但哺乳动物枯草杆菌蛋白酶样蛋白转化酶（SPC）家族的成员最符合条件，它们是分泌途径中的可溶性或膜结合蛋白酶。这些蛋白酶是前体蛋白成熟所必需的，并且在体内和体外都能切割许多细胞和病毒糖蛋白前体中的成对碱性氨基酸基序。为了鉴定gp160加工蛋白酶，我们使用逆转录PCR和Northern印迹分析来确定人类CD4+ T细胞中SPC蛋白酶的谱。我们克隆了SPC家族的新成员，即人类PC6基因。hPC6蛋白酶的两种同工型在人类T细胞中表达，即hPC6A和更大的hPC6B。已将人类T细胞中SPC基因的表达模式与弗林蛋白酶缺陷型LoVo细胞系进行了比较，这两种细胞系都有能力产生传染性HIV病毒粒子。这种比较得出的结论是，hPC6基因产物最有可能是负责人类CD4+ T细胞中HIV-1 gp160加工的宿主细胞蛋白酶的候选者。
