Human papillomavirus type 16 E6 and NFX1-123 mislocalize immune signaling proteins and downregulate immune gene expression in keratinocytes

• Published in: PloS one Vol. 12; no. 11; p. e0187514
• Main Authors: Levan, Justine, Vliet-Gregg, Portia A, Robinson, Kristin L, Katzenellenbogen, Rachel A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08.11.2017; Public Library of Science (PLoS)
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Antigen presentation; Biology and Life Sciences; Cancer; Cervical cancer; Cytokines; Derepression; DNA binding proteins; DNA microarrays; DNA-Binding Proteins - metabolism; Down-Regulation - immunology; Fluorescence; Foreskin - cytology; Gene expression; Gene Knockdown Techniques; Genes; Genetic aspects; Genomes; Health risks; Human papillomavirus; Humans; Immortalization; Immune response; Immune system; Immunity, Innate - genetics; Immunoregulation; Infections; Infectious diseases; Inflammation; Interdisciplinary aspects; Interferon; Keratinocytes; Keratinocytes - immunology; Localization; Male; Medicine and Health Sciences; Methods; Microscopy; Models, Biological; Morbidity; Oligonucleotide Array Sequence Analysis; Oncogene Proteins, Viral - metabolism; Papillomavirus; Physiological aspects; Plasmids; Proteins; Repressor Proteins - metabolism; Research and Analysis Methods; Risk factors; Sexually transmitted diseases; Signal Transduction - genetics; Signal Transduction - immunology; Signaling; STD; Subcellular Fractions - metabolism; Telomerase; TNF Receptor-Associated Factor 6 - metabolism; Up-Regulation - genetics; Virology; United States; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0187514

Human papillomavirus (HPV) is the most prevalent sexually transmitted infection, affecting an estimated 11% of the world's population. The high-risk HPV types (HR HPV) account for approximately 5% of the global burden of cancer and thus cause high morbidity and mortality. Although it is known that persistent infection with HR HPV is the greatest risk factor for developing HPV-associated cancer, and that the HPV early proteins E6 and E7 dysregulate immune detection by its host cells, the mechanisms of immune evasion by HR HPV are not well understood. Previous work in the laboratory identified the endogenous cytoplasmic host protein NFX1-123 as a binding partner of the HR HPV type 16 oncoprotein E6 (16E6). Together NFX1-123 and 16E6 affect cellular growth, differentiation, and immortalization genes and pathways. In a whole genome microarray, human foreskin keratinocytes (HFKs) stably expressing 16E6 and overexpressing NFX1-123 showed a diverse set of innate immune genes downregulated two-fold or more when compared to 16E6 cells with endogenous NFX1-123. We demonstrated that 16E6 and NFX1-123 decreased expression of pro-inflammatory cytokines and interferon-stimulated genes (ISGs) in 16E6 HFKs at the mRNA and protein level. Knock down of NFX1-123 in 16E6 HFKs resulted in a derepression of innate immune genes, pointing to the requirement of NFX1-123 for immune regulation in the context of 16E6. Studies using immunofluorescent microscopy revealed that 16E6 and NFX1-123 disturbed the normal localization of signaling proteins involved in initiating the immune response. This study identifies NFX1-123 as a critical host protein partner through which 16E6 is able to subvert the immune response and in turn permit a long-lived HR HPV infection.