hnRNP L controls HPV16 RNA polyadenylation and splicing in an Akt kinase-dependent manner

Area of Science:

• Molecular Biology
• Virology
• Gene Regulation

Background:

• Human Papillomavirus type 16 (HPV16) is a key factor in cervical cancer development.
• Regulation of HPV16 late gene expression is crucial for viral replication and pathogenesis.
• The role of cellular kinases, like Akt, in controlling viral gene expression is not fully understood.

Purpose of the Study:

• To investigate the mechanism by which Akt kinase influences HPV16 late gene expression.
• To identify the specific RNA processing events regulated by Akt kinase.
• To elucidate the role of RNA-binding proteins in Akt-mediated regulation of HPV16.

Main Methods:

• Utilized HPV16 immortalized keratinocytes and subgenomic expression plasmids.
• Employed siRNA for gene knockdown of Akt and hnRNP L.
• Performed RNA binding protein assays, Western blotting, and RT-qPCR to analyze gene expression and protein interactions.

Main Results:

• Akt kinase inhibition reduced HPV16 early polyadenylation and enhanced HPV16 late L1 mRNA splicing.
• hnRNP L was identified as a key RNA-binding protein associated with HPV16 splice sites and polyadenylation signals.
• Akt inhibition led to hnRNP L dephosphorylation, decreased hnRNP L binding to HPV16 mRNAs, and increased binding of U2AF65 and Sam68.

Conclusions:

• Akt kinase inhibits HPV16 late gene expression via regulation of RNA processing, specifically controlling the RNA-binding protein hnRNP L.
• Akt kinase activity maintains an intracellular environment favoring early HPV16 gene expression while suppressing late gene expression.
• Targeting the Akt/hnRNP L pathway represents a potential strategy for controlling HPV16 gene expression.