Agopian Kristin, Wei Bangdong L, Garcia J Victor, Gabuzda Dana
Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
Virology. 2007 Feb 5;358(1):119-35. doi: 10.1016/j.virol.2006.07.053. Epub 2006 Sep 18.
HIV-1 compartmentalization in the CNS has been demonstrated for gag, pol, and env genes. However, little is known about tissue compartmentalization of nef genes and their functional characteristics in brain. We have cloned 97 nef genes and characterized 10 Nef proteins from autopsy brain and lymphoid tissues from 2 patients with AIDS and HIV-1-associated dementia. Distinct compartmentalization of brain versus lymphoid nef genes was demonstrated within each patient. CD4 and MHC-I downregulation were conserved in all tissue-derived Nefs. However, MHC-I downregulation by brain-derived Nefs was weaker than downregulation by lymphoid-derived Nefs. The motifs KEEE- or EKEE- at the PACS-1 binding site represented brain-specific signature patterns in these 2 patients and contributed to the reduced MHC-I downregulation activity of brain-derived Nefs from these patients. Pak2 association was highly variable in Nefs from both patients. Three of 10 tissue-derived Nefs coimmunoprecipitated activated Pak2, with strong association demonstrated for only 2 Nefs. The ability of Nef to associate with activated Pak2 did not correlate with brain or lymphoid tissue origin. Nef genes from viruses isolated from brain by coculture with PBMC were not closely related to sequences amplified directly from brain tissue, suggesting that viral selection or adaptation occurred during coculture. This study of tissue-derived HIV-1 Nefs demonstrates that CD4 and MHC-I downregulation are highly conserved Nef functions, while Pak2 association is variable in late stage AIDS patients.
已证实HIV-1在中枢神经系统中的gag、pol和env基因存在区室化现象。然而，对于nef基因在脑组织中的区室化及其功能特性却知之甚少。我们从2例艾滋病和HIV-1相关痴呆患者的尸检脑和淋巴组织中克隆了97个nef基因，并对10种Nef蛋白进行了表征。在每位患者体内均证实了脑源与淋巴源nef基因存在明显的区室化。所有组织来源的Nefs均能保守地下调CD4和MHC-I。然而，脑源Nefs对MHC-I的下调作用弱于淋巴源Nefs。在这2例患者中，PACS-1结合位点处的KEEE-或EKEE-基序代表了脑特异性特征模式，并导致这些患者脑源Nefs的MHC-I下调活性降低。在两位患者的Nefs中，Pak2的结合具有高度变异性。10种组织来源的Nefs中有3种通过共免疫沉淀激活了Pak2，仅2种Nefs表现出强结合。Nef与激活的Pak2结合的能力与脑或淋巴组织来源无关。通过与PBMC共培养从脑中分离出的病毒的Nef基因与直接从脑组织中扩增的序列没有密切关系，这表明在共培养过程中发生了病毒选择或适应。这项对组织来源的HIV-1 Nefs的研究表明，CD4和MHC-I下调是高度保守的Nef功能，而在晚期艾滋病患者中，Pak2结合具有变异性。
