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

Naoko Kajitani, Jacob Glahder, Chengjun Wu, Haoran Yu, Kersti Nilsson, Stefan Schwartz

Research output: Contribution to journalArticlepeer-review


Inhibition of the Akt kinase activates HPV16 late gene expression by reducing HPV16 early polyadenylation and by activating HPV16 late L1 mRNA splicing. We identified 'hot spots' for RNA binding proteins at the early polyA signal and at splice sites on HPV16 late mRNAs. We observed that hnRNP L was associated with sequences at all HPV16 late splice sites and at the early polyA signal. Akt kinase inhibition resulted in hnRNP L dephosphorylation and reduced association of hnRNP L with HPV16 mRNAs. This was accompanied by an increased binding of U2AF65 and Sam68 to HPV16 mRNAs. Furthermore, siRNA knock-down of hnRNP L or Akt induced HPV16 gene expression. Treatment of HPV16 immortalized keratinocytes with Akt kinase inhibitor reduced hnRNP L binding to HPV16 mRNAs and induced HPV16 L1 mRNA production. Finally, deletion of the hnRNP L binding sites in HPV16 subgenomic expression plasmids resulted in activation of HPV16 late gene expression. In conclusion, the Akt kinase inhibits HPV16 late gene expression at the level of RNA processing by controlling the RNA-binding protein hnRNP L. We speculate that Akt kinase activity upholds an intracellular milieu that favours HPV16 early gene expression and suppresses HPV16 late gene expression.

Original languageEnglish
Pages (from-to)9654-9678
Number of pages25
JournalNucleic Acids Research
Issue number16
Publication statusPublished - 2017 Sept 19

Subject classification (UKÄ)

  • Microbiology in the medical area


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