Interferon-inducible expression of APOBEC3 editing enzymes in human hepatocytes and inhibition of hepatitis B virus replication
Interferon-inducible expression of APOBEC3 editing enzymes in human hepatocytes and inhibition of hepatitis B virus replication
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DOI：
10.1002/hep.21187
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发表时间：
2006-06-01
期刊：
影响因子：
13.5
通讯作者：
Greeve, Jobst
中科院分区：
文献类型：
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作者：
Bonvin, Marianne;Achermann, Francois;Greeve, Jobst
已在体外和体内检测到 APOBEC3 胞苷脱氨酶引起的乙型肝炎病毒 (HBV) DNA 超突变，并且 APOBEC3G (A3G) 和 A-POBEC3F (A3F) 已被证明可以在体外抑制 HBV 复制，但这些酶的肝脏表达可能较低甚至不存在，这引发了对其生理学的质疑。 对乙肝病毒复制的影响。我们发现正常人肝脏表达 APOBEC3B (A3B)、APOBEC3C (A3C)、A3F 和 A3G 的 mRNA。在原代人肝细胞中，干扰素 α (IFN-α) 刺激这些胞苷脱氨酶的表达高达 14 倍，相对于 GAPDH mRNA 丰度，A3G、A3F 和 A3B 的 mRNA 表达水平分别达到 10%、3% 和 3%。转染时，全长蛋白 A3B(L) 在体外与 A3G 或 A3F 一样有效地抑制 HBV 复制，而截短的剪接变体 A3B(S) 和 A3C 则没有效果。 A3B(L) 和 A3B(S) 主要在未感染细胞的细胞核中检测到；然而，在表达 HBV 的细胞中，这两种蛋白也在细胞质中被发现，并且与 HBV 病毒颗粒相关，类似于 A3G 和 A3F。此外，A3G、A3F 和 A3B(L)（而非 A3B(S））在复制的 HBV 基因组的一部分中诱导了广泛的 G 至 A 超突变。总之，编辑酶 A3B(L)、A3F 和最显着的 A3G 在肝脏中表达，并在肝细胞中被 IFN-α 上调，是促进 HBV 非溶细胞性清除的候选酶。
Hypermutations in hepatitis B virus (HBV) DNA by APOBEC3 cytidine deaminases have been detected in vitro and in vivo, and APOBEC3G (A3G) and A-POBEC3F (A3F) have been shown to inhibit the replication of HBV in vitro, but the presumably low or even absent hepatic expression of these enzymes has raised the question as to their physiological impact on HBV replication. We show that normal human liver expresses the mRNAs of APOBEC3B (A3B), APOBEC3C (A3C), A3F, and A3G. In primary human hepatocytes, interferon alpha (IFN-alpha) stimulated the expression of these cytidine deaminases up to 14-fold, and the mRNAs of A3G, A3F, and A3B reached expression levels of 10%, 3%, and 3%, respectively, relative to GAPDH mRNA abundance. On transfection, the full-length protein A3B(L) inhibited HBV replication in vitro as efficiently as A3G or A3F, whereas the truncated splice variant A3B(S) and A3C had no effect. A3B(L) and A3B(S) were detected predominantly in the nucleus of uninfected cells; however, in HBV-expressing cells both proteins were found also in the cytoplasm and were associated with HBV viral particles, similarly to A3G and A3F. Moreover, A3G, A3F, and A3B(L), but not A3B(S), induced extensive G-to-A hypermutations in a fraction of the replicated HBV genomes. In conclusion, the editing enzymes A3B(L), A3F, and most markedly A3G, which are expressed in liver and up-regulated by IFN-alpha in hepatocytes, are candidates to contribute to the noncytolytic clearance of HBV.