Identification of TRAPPC8 as a host factor required for human papillomavirus cell entry

• Published in: PloS one Vol. 8; no. 11; p. e80297
• Main Authors: Ishii, Yoshiyuki, Nakahara, Tomomi, Kataoka, Michiyo, Kusumoto-Matsuo, Rika, Mori, Seiichiro, Takeuchi, Takamasa, Kukimoto, Iwao
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14-11-2013; Public Library of Science (PLoS)
• Subjects: Autophagy; Blotting, Western; Cancer; Cell adhesion; Cell surface; Cellular proteins; Circular DNA; Deoxyribonucleic acid; Destabilization; Disease susceptibility; Dispersal; DNA; Endocytosis; Flow Cytometry; Gene expression; Genomes; Genomics; Golgi apparatus; Growth factors; Health aspects; HeLa Cells; Heparan sulfate; Human papillomavirus; Human papillomavirus 16 - genetics; Human papillomavirus 16 - pathogenicity; Human papillomavirus 16 - physiology; Humans; Immunofluorescence; Infections; Infectious diseases; Internalization; Intracellular; Kinases; Microscopy; Microscopy, Fluorescence; Nuclei; Papillomaviridae - genetics; Papillomaviridae - pathogenicity; Papillomaviridae - physiology; Papillomavirus; Papillomavirus infections; Pathogens; Phenotypes; Protein transport; Proteins; Reporter gene; trans-Golgi Network - metabolism; Vesicular Transport Proteins - metabolism; Viral proteins; Virions; Virology; Viruses; Yeast; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0080297

Human papillomavirus (HPV) is a non-enveloped virus composed of a circular DNA genome and two capsid proteins, L1 and L2. Multiple interactions between its capsid proteins and host cellular proteins are required for infectious HPV entry, including cell attachment and internalization, intracellular trafficking and viral genome transfer into the nucleus. Using two variants of HPV type 51, the Ma and Nu strains, we have previously reported that MaL2 is required for efficient pseudovirus (PsV) transduction. However, the cellular factors that confer this L2 dependency have not yet been identified. Here we report that the transport protein particle complex subunit 8 (TRAPPC8) specifically interacts with MaL2. TRAPPC8 knockdown in HeLa cells yielded reduced levels of reporter gene expression when inoculated with HPV51Ma, HPV16, and HPV31 PsVs. TRAPPC8 knockdown in HaCaT cells also showed reduced susceptibility to infection with authentic HPV31 virions, indicating that TRAPPC8 plays a crucial role in native HPV infection. Immunofluorescence microscopy revealed that the central region of TRAPPC8 was exposed on the cell surface and colocalized with inoculated PsVs. The entry of Ma, Nu, and L2-lacking PsVs into cells was equally impaired in TRAPPC8 knockdown HeLa cells, suggesting that TRAPPC8-dependent endocytosis plays an important role in HPV entry that is independent of L2 interaction. Finally, expression of GFP-fused L2 that can also interact with TRAPPC8 induced dispersal of the Golgi stack structure in HeLa cells, a phenotype also observed by TRAPPC8 knockdown. These results suggest that during viral intracellular trafficking, binding of L2 to TRAPPC8 inhibits its function resulting in Golgi destabilization, a process that may assist HPV genome escape from the trans-Golgi network.