GSE174317
Ecdysoneless protein regulates viral and cellular mRNA splicing to promote cervical oncogenesis
The high-risk subgroup of Human papilloma viruses (HPVs), exemplified by HPV16/18, are causally linked to human cancers of the anogenital tract, skin, and upper aerodigestive tract.  The high-risk HPV oncoproteins E6 and E7 are expressed from a polycistronic transcript that can potentially give rise to alternatively spliced E6 mRNAs, a process important for E6 and E7  expression and oncogenic transformation. Previously, we identified ECD, the human homologue of the Drosophila ecdysoneless gene, as a novel HPV16 E6-interacting protein using Yeast two-hybrid system. Here, we show that the C-terminal region of ECD selectively binds to high-risk but not to low-risk HPV E6 proteins. We demonstrate that ECD is overexpressed in HPV+ as well as HPV- cervical and head and neck patient tumor samples. Using the TCGA dataset, we show that ECD mRNA overexpression predicts shorter survival in these cancer patients.  Recent work from our laboratory showed that ECD associates with several components of RNA biogenesis/splicing machinery and are involved in mRNA export. Here, we show that ECD is an RNA binding protein and regulates mRNA splicing. RNAseq analyses of SiHa cells upon ECD knockdown (KD) revealed alterations of many cellular pathways with prominent downregulation of components of the mRNA splicing machinery. Further investigation revealed that ECD KD resulted in dysregulation of E6 RNA splicing, resulting in decreased E7 and increased RB protein. Furthermore, ECD KD dysregulated several cellular mRNAs known to be critical for HPV oncogenesis. Finally, we demonstrate that while ECD KD in cervical cancer cell lines led to a reduction in oncogenic traits, ECD overexpression together with E7 led to the immortalization of keratinocytes. Taken together, our results support a novel role of ECD in transcription and in viral and cellular mRNA splicing to support HPV-driven oncogenesis. Overall design: ECD role in viral and cellular splicing