Ghone Dhaval, Evans Edward L, Bandini Madison, Stephenson Kaelyn G, Sherer Nathan M, Suzuki Aussie
McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Biophysics Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin, USA.
bioRxiv. 2024 Nov 25:2024.07.30.605839. doi: 10.1101/2024.07.30.605839.
Virion Infectivity Factor (Vif) of the Human Immunodeficiency Virus type 1 (HIV-1) targets and degrades cellular APOBEC3 proteins, key regulators of intrinsic and innate antiretroviral immune responses, thereby facilitating HIV-1 infection. While Vif's role in degrading APOBEC3G is well-studied, Vif is also known to cause cell cycle arrest, but the detailed nature of Vif's effects on the cell cycle has yet to be delineated. In this study, we employed high-temporal single-cell live imaging and super-resolution microscopy to monitor individual cells during Vif-induced cell cycle arrest. Our findings reveal that Vif does not affect the G2/M boundary as previously thought. Instead, Vif triggers a unique and robust pseudo-metaphase arrest, distinct from the mild prometaphase arrest induced by Vpr. During this arrest, chromosomes align properly and form the metaphase plate, but later lose alignment, resulting in polar chromosomes. Notably, Vif, unlike Vpr, significantly reduces the levels of both Protein Phosphatase 1 (PP1) and 2A (PP2A) at kinetochores, which regulate chromosome-microtubule interactions. These results unveil a novel role for Vif in kinetochore regulation that governs the spatial organization of chromosomes during mitosis.
1型人类免疫缺陷病毒（HIV-1）的病毒体感染性因子（Vif）靶向并降解细胞中的载脂蛋白B mRNA编辑酶催化多肽样3（APOBEC3）蛋白，这些蛋白是固有和先天性抗逆转录病毒免疫反应的关键调节因子，从而促进HIV-1感染。虽然Vif在降解APOBEC3G方面的作用已得到充分研究，但Vif也已知会导致细胞周期停滞，但其对细胞周期影响的详细性质尚未明确。在本研究中，我们采用高时间分辨率的单细胞实时成像和超分辨率显微镜技术，来监测Vif诱导细胞周期停滞过程中的单个细胞。我们的研究结果表明，Vif并不像之前认为的那样影响G2/M边界。相反，Vif会引发一种独特且强烈的假中期停滞，这与Vpr诱导的轻度前中期停滞不同。在这种停滞期间，染色体正确排列并形成中期板，但随后失去排列，导致染色体两极化。值得注意的是，与Vpr不同，Vif会显著降低动粒处的蛋白磷酸酶1（PP1）和2A（PP2A）的水平，而这两种酶调节染色体与微管的相互作用。这些结果揭示了Vif在动粒调节中的新作用，该作用在有丝分裂过程中控制染色体的空间组织。
