ZAP isoforms regulate unfolded protein response and epithelial- mesenchymal transition

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Human Zinc-finger Antiviral Protein (ZAP) inhibits viruses like HIV by targeting viral RNAs.
• The roles of ZAP isoforms (ZAPL and ZAPS) in regulating host mRNAs and cellular functions remain largely uncharacterized.
• Understanding ZAP isoform regulation is crucial for their antiviral functions and potential therapeutic applications.

Purpose of the Study:

• To investigate the regulatory mechanisms controlling ZAP isoform production.
• To identify host mRNA targets regulated by ZAP isoforms.
• To elucidate the cellular functions influenced by ZAP isoforms, including the unfolded protein response (UPR) and epithelial-mesenchymal transition (EMT).

Main Methods:

• Investigated ZAPS production inhibition by splicing factors hnRNPA1/A2, PTBP1/2, and U1-snRNP.
• Utilized splice-switching antisense oligonucleotides to modulate ZAPL/S balance in human cells.
• Performed transcriptomic analysis on ZAP-isoform-specific knockout cells.
• Determined subcellular localization of ZAP isoforms using endogenous tagging.
• Assessed ZAP isoform effects on UPR, ER stress, and EMT-related cell migration.

Main Results:

• Splicing factors hnRNPA1/A2, PTBP1/2, and U1-snRNP inhibit ZAPS production.
• Modulation of ZAPL/S balance is feasible using antisense oligonucleotides.
• ZAPL and ZAPS target distinct sets of host mRNAs involved in UPR, EMT, and innate immunity.
• ZAPL and ZAPS exhibit differential localization (membrane and cytosol, respectively), correlating with target specificity.
• ZAP isoforms differentially regulate UPR branches, cell viability during ER stress, and EMT-related cell migration in a cell-type-dependent manner.

Conclusions:

• The balance between ZAP splicing and other RNA processing pathways is a target for modulating ZAP isoform activity.
• This study identifies novel host transcripts and cellular processes regulated by ZAP isoforms.
• Findings provide insights into ZAP's multifaceted roles beyond direct antiviral activity, impacting fundamental cellular functions.