Hypermutation of ApoB mRNA by Rat APOBEC-1 Overexpression Mimics APOBEC-3 Hypermutation

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• 作者：Zhigang Chen¹ ; Thomas L. Eggerman¹ ; ² ; Alexander V. Bocharov¹ ; Irina N. Baranova¹ ; Tatyana G. Vishnyakova¹ ; Roger J. Kurlander¹ ; Gyorgy Csako¹ ; Amy P. Patterson¹ ; ³ ; ^{pattersa@od.nih.gov}
• 关键词：apoB ; apolipoprotein B ; A3G ; APOBEC-3G ; HIV-1 ; human immunodeficiency virus type 1 ; RT ; reverse transcription ; MLV ; murine leukemia virus ; HTLV-1 ; human T-cell leukemia virus type 1 ; HBV ; hepatitis B virus ; 3D-PCR ; differential DNA denaturation PCR ; A3C
• 刊名：Journal of Molecular Biology
• 出版年：2012
• 期刊代码：102_00222836
• 类别：imm
• 出版时间：20 April, 2012
• 卷：418
• 期：1-2
• 页码：65-81
• 文件大小：1431 K

摘要

APOBEC-3 proteins induce C-to-U hypermutations in the viral genome of various viruses and have broad antiviral activity. Generally, only a small proportion of viral genomes ( <  10^鈭?#xA0;2) are hypermutated by APOBEC-3s, but often many cytidines (up to 40%) are converted into uridine. The mechanism of this unique selective hypermutation remains unknown. We found that rat APOBEC-1 overexpression had a hypermutation pattern similar to that of APOBEC-3s on its substrate apolipoprotein B (apoB) mRNA. Transient plasmid transfection of rat APOBEC-1 resulted in 0.4%and 1.8%hypermutations with apoB mRNA in HepG2 and McA7777 cells, respectively. The low frequency of hypermutated apoB mRNA targets was enriched by differential DNA denaturation PCR at 72-76聽掳C, with hypermutation levels increasing up to 67%. Up to 69.6%of cytidines in HepG2 and up to 75.5%of cytidines in McA7777 cells were converted into uridines in the hypermutated apoB mRNA. When rat APOBEC-1 was overexpressed by adenovirus, the hypermutation frequency of apoB mRNA increased from 0.4%to 鈭?#xA0;20%and was readily detected by regular PCR. However, this higher expression efficiency only increased the frequency of hypermutation, not the number of affected cytidines in hypermutated targets. Rat APOBEC-1 hypermutation was modulated by cofactors and eliminated by an E181Q mutation, indicating the role of cofactors in hypermutation. The finding of an APOBEC-3 hypermutation pattern with rat APOBEC-1 suggests that cofactors could also be involved in APOBEC-3 hypermutation. Using hepatitis B virus hypermutation, we found that KSRP increased APOBEC-3C and APOBEC-3B hypermutation. These data show that, like rat APOBEC-1 hypermutation, cellular factors may play a regulatory role in APOBEC-3 hypermutation.