Zika virus induces neural progenitor cell mitotic catastrophe by depleting nuclear PNKP while activating cytoplasmic CDK1 despite the DNA damage

Abstract

The 2015-2017 Zika virus (ZIKV) outbreak in Brazil and subsequent international epidemic revealed the strong association between ZIKV infection and congenital malformations. Vertical transmission leads with high frequency to congenital ZIKV syndrome (CZS). CZS is defined by neurodevelopmental and neurodegenerative defects, of which microcephaly is of the greatest concern. The scale and global expansion of the epidemic, the new ZIKV outbreaks (Kerala state, India, 2021), and the potential burden of future ones pose a serious ongoing risk. However, the mechanisms of congenital neurodevelopmental pathologies, including direct cytotoxicity to neural progenitor cells (NPC), placental insufficiency, and immune responses, remain incompletely understood. At the cellular level, microcephaly typically results from death or insufficient proliferation of NPC and cortical neurons. The rapid proliferation of NPC requires efficient DNA damage responses to ensure the genome stability during neurodevelopment. Like congenital ZIKV infection, mutations in the polynucleotide 5’-kinase 3’-phosphatase (PNKP) gene, which encodes a critical DNA damage repair enzyme, produce recessive syndromes often characterized by congenital microcephaly with seizures (MCSZ). We thus tested whether there are any links between ZIKV and PNKP.

Here we show that the PNKP phosphatase inhibitor A12B4C3 inhibited ZIKV replication in NPC and non-neural cells. PNKP relocalized from the nucleus to the cytoplasm in infected cells, co-localizing with the marker of ZIKV replication factories (RF) NS1, resulting in functional nuclear PNKP depletion. Consequently, infected NPC accumulated DNA damage. However, they failed to activate the DNA damage checkpoint kinases Chk1 and Chk2. ZIKV infection induced accumulation and activation of cytoplasmic CycA/CDK1 complexes, which trigger unscheduled mitotic entry. Inhibition of CDK1 activity inhibited ZIKV replication and the formation of RF, suggesting a role of cytoplasmic CycA/CDK1 in RF morphogenesis. The unscheduled mitotic entry in the presence of DNA damage results in mitotic catastrophe (MC). In brief, ZIKV infection induces mitotic catastrophe resulting from unscheduled mitotic entry in the presence of DNA damage. PNKP and CycA/CDK1 are thus host factors playing critical roles in ZIKV replication.