Zika virus infection induces endoplasmic reticulum stress and apoptosis in placental trophoblasts

Authors

Philma Glora Muthuraj, University of Nebraska - LincolnFollow
Prakash K. Sahoo, University of Nebraska - LincolnFollow
Madison Kraus, University of Nebraska - Lincoln
Taylor Bruett, University of Nebraska - LincolnFollow
Arun S. Annamalai, University of Nebraska - LincolnFollow
Aryamav Pattnaik, University of Nebraska - LincolnFollow
Siddappa N. Byrareddy, University of Nebraska - Lincoln
Sathish Kumar Natarajan, University of Nebraska - LincolnFollow

ORCID IDs

Siddappa N. Byrareddy

Sathish Kumar Natarajan

Date of this Version

1-26-2021

Citation

Muthuraj et al. Cell Death Discovery (2021) 7:24 https://doi.org/10.1038/s41420-020-00379-8

Comments

CC-BY

Abstract

Zika virus (ZIKV) infection to a pregnant woman can be vertically transmitted to the fetus via the placenta leading to Congenital Zika syndrome. This is characterized by microcephaly, retinal defects, and intrauterine growth retardation. ZIKV induces placental trophoblast apoptosis leading to severe abnormalities in the growth and development of the fetus. However, the molecular mechanism behind ZIKV-induced apoptosis in placental trophoblasts remains unclear. We hypothesize that ZIKV infection induces endoplasmic reticulum (ER) stress in the trophoblasts, and sustained ER stress results in apoptosis. HTR-8 (HTR-8/SVneo), a human normal immortalized trophoblast cell and human choriocarcinoma-derived cell lines (JEG-3 and JAR) were infected with ZIKV. Biochemical and structural markers of apoptosis like caspase 3/7 activity and percent apoptotic nuclear morphological changes, respectively were assessed. ZIKV infection in placental trophoblasts showed an increase in the levels of CHOP mRNA and protein expression, which is an inducer of apoptosis. Next, we also observed increased levels of ER stress markers such as phosphorylated forms of inositol-requiring transmembrane kinase/endoribonuclease 1α (P-IRE1α), and its downstream target, the spliced form of XBP1 mRNA, phosphorylated eukaryotic initiation factor 2α (P-eIF2α), and activation of cJun N-terminal Kinase (JNK) and p³⁸ mitogen activated protein kinase (MAPK) after 16–24 h of ZIKV infection in trophoblasts. Inhibition of JNK or pan-caspases using small molecule inhibitors significantly prevented ZIKV-induced apoptosis in trophoblasts. Further, JNK inhibition also reduced XBP1 mRNA splicing and viral E protein staining in ZIKV infected cells. In conclusion, the mechanism of ZIKV-induced placental trophoblast apoptosis involves the activation of ER stress and JNK activation, and the inhibition of JNK dramatically prevents ZIKV-induced trophoblast apoptosis.