Suppression of HPV-16 late L1 5'-splice site SD3632 by binding of hnRNP D proteins and hnRNP A2/B1 to upstream AUAGUA RNA motifs

Nucleic Acids Res. 2013 Dec;41(22):10488-508. doi: 10.1093/nar/gkt803. Epub 2013 Sep 5.

Abstract

Human papillomavirus type 16 (HPV-16) 5'-splice site SD3632 is used exclusively to produce late L1 mRNAs. We identified a 34-nt splicing inhibitory element located immediately upstream of HPV-16 late 5'-splice site SD3632. Two AUAGUA motifs located in these 34 nt inhibited SD3632. Two nucleotide substitutions in each of the HPV-16 specific AUAGUA motifs alleviated splicing inhibition and induced late L1 mRNA production from episomal forms of the HPV-16 genome in primary human keratinocytes. The AUAGUA motifs bind specifically not only to the heterogeneous nuclear RNP (hnRNP) D family of RNA-binding proteins including hnRNP D/AUF, hnRNP DL and hnRNP AB but also to hnRNP A2/B1. Knock-down of these proteins induced HPV-16 late L1 mRNA expression, and overexpression of hnRNP A2/B1, hnRNP AB, hnRNP DL and the two hnRNP D isoforms hnRNP D37 and hnRNP D40 further suppressed L1 mRNA expression. This inhibition may allow HPV-16 to hide from the immune system and establish long-term persistent infections with enhanced risk at progressing to cancer. There is an inverse correlation between expression of hnRNP D proteins and hnRNP A2/B1 and HPV-16 L1 production in the cervical epithelium, as well as in cervical cancer, supporting the conclusion that hnRNP D proteins and A2/B1 inhibit HPV-16 L1 mRNA production.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Capsid Proteins / biosynthesis
  • Capsid Proteins / genetics*
  • Cell Line
  • Gene Expression Regulation, Viral*
  • HeLa Cells
  • Heterogeneous-Nuclear Ribonucleoprotein D / metabolism*
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / metabolism*
  • Human papillomavirus 16 / genetics*
  • Humans
  • Keratinocytes / virology
  • Nucleotide Motifs
  • Oncogene Proteins, Viral / biosynthesis
  • Oncogene Proteins, Viral / genetics*
  • RNA Splice Sites*
  • RNA Splicing
  • RNA, Messenger / biosynthesis
  • RNA, Viral / chemistry*
  • Regulatory Sequences, Ribonucleic Acid
  • Sequence Deletion

Substances

  • Capsid Proteins
  • Heterogeneous-Nuclear Ribonucleoprotein D
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B
  • Oncogene Proteins, Viral
  • RNA Splice Sites
  • RNA, Messenger
  • RNA, Viral
  • Regulatory Sequences, Ribonucleic Acid
  • L1 protein, Human papillomavirus type 16