title: The lytic activation of KSHV during keratinocyte differentiation is dependent upon a suprabasal position, the loss of integrin engagement, and calcium, but not the interaction of cadherins.
abstract: We previously found that KSHV (HHV-8) lytic activation occurs during differentiation of oral keratinocytes in organotypic raft cultures. To further investigate the spatial and temporal aspects of KSHV lytic activation and the roles of integrins, cadherins, and calcium, we used rKSHV.219-infected primary oral keratinocytes in submerged, suspension, and direct suprabasal plating, models of differentiation. We found that early keratinocyte differentiation did not activate lytic KSHV in cells attached to a substratum, with activation only occurring in suprabasal cells. Temporally, KSHV lytic expression occurred between the expression of early and late differentiation markers. Keratinocytes differentiated in suspension culture, which mimics substratum loss that occurs with stratification, activated lytic KSHV. This lytic activation was inhibited by integrin engagement, showing that integrins are a control point for KSHV reactivation. A role for cadherins was not found. Elevated extracellular calcium was necessary, but not sufficient, for lytic activation.
authors.affiliation: Department of Oral Biology, School of Dentistry, University of Washington, Seattle, WA 98109-8070, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Seifi
authors.forename: Edward M
authors.initials: EM
authors.lastname: Weaver
authors.forename: Mark E
authors.initials: ME
authors.lastname: Whipple
authors.forename: Minako
authors.initials: M
authors.lastname: Ikoma
authors.forename: James
authors.initials: J
authors.lastname: Farrenberg
authors.forename: Meei-Li
authors.initials: ML
authors.lastname: Huang
authors.forename: Jeffery
authors.initials: J
authors.lastname: Vieira
mesh_terms: D015820:Cadherins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D015967:Gene Expression Regulation, Viral; D019288:Herpesvirus 8, Human / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology* / Q000821:virology*; D009061:Mouth Mucosa / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: D015820:Cadherins; D017874:Immediate-Early Proteins; D016023:Integrins; D012333:RNA, Messenger; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D002118:Calcium