Biochemical and Biophysical Research Communications
Inhibition of Hepatitis B virus replication by SAMHD1
Introduction
Hosts have evolved diverse mechanisms to defend themselves against viral infection. Intrinsic immunity mediated by constitutively expressed restriction factors is the recently recognized way to block viral replication, which is somewhat different from the conventional innate immunity [1]. In 2011, Sterile alpha motif and HD-domain containing protein 1 (SAMHD1) was identified as a novel intracellular antiviral factor in intrinsic immunity [2], [3], [4]. By depleting the deoxynucleoside triphosphates (dNTPs) pool of host cells to a low level that cannot support the efficient synthesis of viral cDNA, SAMHD1 restricts replication of Human immunodeficiency virus type 1 (HIV-1) [5], [6], [7]. Besides HIV-1, SAMHD1 has been found to inhibit replication of other retroviruses [8], [9], [10]. Recent studies further demonstrated SAMHD1 restricted DNA viruses in non-dividing myeloid cells by limiting DNA replication [11], [12].
Hepatitis B virus is a DNA virus whose infection accounts for approximately 1 million deaths per year from cirrhosis, liver failure and hepatocellular carcinoma (HCC) [13]. As a nonretroviral virus, HBV experiences a process of reverse transcription in its life cycle akin to that of lentiviruses [14]. SAMHD1 was found to be expressed in human liver [15]. However, whether HBV replication can be inhibited by human SAMHD1 in hepatocytes is unknown.
In the present study, we examined the role of SAMHD1 in HBV replication in liver cells. We found IFN-α-inducible SAMHD1 could inhibit HBV replication in liver cells without depleting intracellular dNTPs.
Section snippets
Plasmids
pHBVwt, which contained HBV1.3L (replication-competent overlength 1.3-fold HBV), and its mutant pHBV ΔX (HBx defective) were generous gifts from Dr. James Ou (University of Southern California), and had been described previously [16]. pcDNA3.1-HA-SAMHD1wt (pSAMHD1wt) and pcDNA3.1-HA-SAMHD1 HD/AA (pSAMHD1 HD/AA) were kind gifts from Dr. Klaus Strebel (National Institutes of Health). pRL-TK (Promega) was used to correct for transfection efficiency and luciferase activities were measured using
SAMHD1 expression is detectable in four liver cell lines
To investigate whether SAMHD1 restricted HBV replication in liver cells, we firstly detected endogenous expression of SAMHD1 in four liver cell lines: HepG2, LO2, BEL-7402, SMMC-7721. BEL-7402 cells transiently expressing exogenous SAMHD1 was regarded as a positive control for SAMHD1 expression. As showed in Fig. 1A, SAMHD1 expression was detectable in all four liver cell lines using Western blot whilst it was over-expressed in transfected BEL-7402 cells. These results were further confirmed by
Discussion
It has been well known that SAMHD1 restricts replication of retroviruses [8], [9], [10]. Recent studies showed SAMHD1 also blocked replication of two double stranded DNA viruses, vaccinia virus and herpes simplex virus 1, by depleting dNTPs in non-dividing myeloid cells [11], [12]. Here we provided evidence that SAMHD1 inhibited replication of HBV, another DNA virus, in liver cells. Remarkably, the catalytically inactive mutant, SAMHD1 HD/AA also hampered HBV replication, suggesting SAMHD1 had
Acknowledgments
We would like to thank Dr. James Ou (University of Southern California) and Dr. Klaus Strebel (National Institutes of Health) who kindly provided reagents used in this study. We also thank Dake Huang and Cuiping Ren (Anhui Medical University) for their technical help. This work was supported by grants from National Undergraduate Training Programs for Innovation and Entrepreneurship-China (No. 201310366009 to Zhangming Chen), National Natural Science Foundation of China (Nos. 81173074 and
References (27)
- et al.
Aicardi–Goutieres syndrome gene and HIV-1 restriction factor SAMHD1 is a dGTP-regulated deoxynucleotide triphosphohydrolase
J. Biol. Chem.
(2011) - et al.
Contribution of SAM and HD domains to retroviral restriction mediated by human SAMHD1
Virology
(2013) - et al.
Host restriction factor SAMHD1 limits human T Cell leukemia virus type 1 infection of monocytes via STING-mediated apoptosis
Cell Host Microbe
(2013) - et al.
Identification of human homologue of mouse IFN-γ induced protein from human dendritic cells
Immunol. Lett.
(2000) - et al.
Modulation of LINE-1 and Alu/SVA retrotransposition by Aicardi–Goutières syndrome-related SAMHD1
Cell Rep.
(2013) - et al.
Hepatitis B virus regulatory HBx protein binding to DDB1 is required but is not sufficient for maximal HBV replication
Virology
(2012) - et al.
Intrinsic antiviral immunity
Nat. Immunol.
(2012) - et al.
SAMHD1: a novel antiviral factor in intrinsic immunity
Future Microbiol.
(2012) - et al.
SAMHD1 is the dendritic- and myeloid-cell-specific HIV-1 restriction factor counteracted by Vpx
Nature
(2011) - et al.
Vpx relieves inhibition of HIV-1 infection of macrophages mediated by the SAMHD1 protein
Nature
(2011)
HIV-1 restriction factor SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase
Nature
SAMHD1 restricts the replication of human immunodeficiency virus type 1 by depleting the intracellular pool of deoxynucleoside triphosphates
Nat. Immunol.
Restriction of diverse retroviruses by SAMHD1
Retrovirology
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2020, Journal of Biological ChemistryCitation Excerpt :SAMHD1 can also block infections of other retroviruses, such as feline immunodeficiency virus, murine leukemia virus, equine infectious anemia virus, and human T cell leukemia virus type 1 (12, 13). Furthermore, SAMHD1 can block the infections of several DNA viruses, including hepatitis B virus, vaccinia virus, and herpes simplex virus type I in noncycling myeloid cells (14–17). Interestingly, viral proteins are able to counteract SAMHD1-mediated restriction of viral infections.
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These authors contributed equally to this work.