Donahue Daniel A, Amraoui Sonia, di Nunzio Francesca, Kieffer Camille, Porrot Françoise, Opp Silvana, Diaz-Griffero Felipe, Casartelli Nicoletta, Schwartz Olivier
Institut Pasteur, Department of Virology, Virus & Immunity Unit, Paris, France
CNRS URA 3015, Paris, France.
J Virol. 2016 Mar 28;90(8):4199-4214. doi: 10.1128/JVI.03202-15. Print 2016 Apr.
In a previous screen of putative interferon-stimulated genes, SUN2 was shown to inhibit HIV-1 infection in an uncharacterized manner. SUN2 is an inner nuclear membrane protein belonging to the linker of nucleoskeleton and cytoskeleton complex. We have analyzed here the role of SUN2 in HIV infection. We report that in contrast to what was initially thought, SUN2 is not induced by type I interferon, and that SUN2 silencing does not modulate HIV infection. However, SUN2 overexpression in cell lines and in primary monocyte-derived dendritic cells inhibits the replication of HIV but not murine leukemia virus or chikungunya virus. We identified HIV-1 and HIV-2 strains that are unaffected by SUN2, suggesting that the effect is specific to particular viral components or cofactors. Intriguingly, SUN2 overexpression induces a multilobular flower-like nuclear shape that does not impact cell viability and is similar to that of cells isolated from patients with HTLV-I-associated adult T-cell leukemia or with progeria. Nuclear shape changes and HIV inhibition both mapped to the nucleoplasmic domain of SUN2 that interacts with the nuclear lamina. This block to HIV replication occurs between reverse transcription and nuclear entry, and passaging experiments selected for a single-amino-acid change in capsid (CA) that leads to resistance to overexpressed SUN2. Furthermore, using chemical inhibition or silencing of cyclophilin A (CypA), as well as CA mutant viruses, we implicated CypA in the SUN2-imposed block to HIV infection. Our results demonstrate that SUN2 overexpression perturbs both nuclear shape and early events of HIV infection.
Cells encode proteins that interfere with viral replication, a number of which have been identified in overexpression screens. SUN2 is a nuclear membrane protein that was shown to inhibit HIV infection in such a screen, but how it blocked HIV infection was not known. We show that SUN2 overexpression blocks the infection of certain strains of HIV before nuclear entry. Mutation of the viral capsid protein yielded SUN2-resistant HIV. Additionally, the inhibition of HIV infection by SUN2 involves cyclophilin A, a protein that binds the HIV capsid and directs subsequent steps of infection. We also found that SUN2 overexpression substantially changes the shape of the cell's nucleus, resulting in many flower-like nuclei. Both HIV inhibition and deformation of nuclear shape required the domain of SUN2 that interacts with the nuclear lamina. Our results demonstrate that SUN2 interferes with HIV infection and highlight novel links between nuclear shape and viral infection.
在先前对假定的干扰素刺激基因的筛选中，SUN2被证明以一种未明确的方式抑制HIV-1感染。SUN2是一种属于核骨架与细胞骨架连接复合体的内核膜蛋白。我们在此分析了SUN2在HIV感染中的作用。我们报告称，与最初的想法相反，SUN2不是由I型干扰素诱导的，并且SUN2沉默不会调节HIV感染。然而，在细胞系和原代单核细胞衍生的树突状细胞中过表达SUN2会抑制HIV的复制，但不会抑制鼠白血病病毒或基孔肯雅病毒。我们鉴定出不受SUN2影响的HIV-1和HIV-2毒株，这表明这种效应特定于特定的病毒成分或辅助因子。有趣的是，SUN2过表达会诱导多叶花状的核形态，这不会影响细胞活力，并且与从HTLV-I相关成人T细胞白血病患者或早衰患者分离的细胞相似。核形态变化和HIV抑制都定位于SUN2与核纤层相互作用的核质结构域。这种对HIV复制的阻断发生在逆转录和核进入之间，传代实验筛选出衣壳（CA）中的一个单氨基酸变化，该变化导致对过表达的SUN2产生抗性。此外，使用亲环素A（CypA）的化学抑制或沉默以及CA突变病毒，我们发现CypA参与了SUN2对HIV感染的阻断。我们的结果表明，SUN2过表达会扰乱核形态和HIV感染的早期事件。
细胞编码干扰病毒复制的蛋白质，其中许多已在过表达筛选中被鉴定出来。SUN2是一种核膜蛋白，在这样的筛选中被证明能抑制HIV感染，但它如何阻断HIV感染尚不清楚。我们表明，SUN2过表达在核进入之前阻断某些HIV毒株的感染。病毒衣壳蛋白的突变产生了对SUN2耐药的HIV。此外，SUN2对HIV感染的抑制涉及亲环素A，一种与HIV衣壳结合并指导后续感染步骤的蛋白质。我们还发现，SUN2过表达会显著改变细胞核的形状，导致许多花状核。HIV抑制和核形态变形都需要SUN2与核纤层相互作用的结构域。我们的结果表明，SUN2干扰HIV感染，并突出了核形态与病毒感染之间的新联系。
