title: Up-regulated expression of Sp1 protein coincident with a viral protein in human and mouse differentiating keratinocytes may act as a cell differentiation marker.
abstract: Sp1 is a transcription factor that regulates expression of mammalian and viral genes and is involved in different facets of cellular functions in eukaryotic cells. Here, we investigated Sp1 expression in primary mouse and human keratinocyte (KC) culture using quantitative reverse transcriptase polymerase chain reaction, Western blot, and immunofluorescence microscopy. Expression of Sp1 was post-transcriptionally up-regulated with increasing time in primary KC cultures. Sp1 expression, coincident with expression of human papillomavirus L1 capsid protein and involucrin, was associated with cell differentiation in vitro and in vivo in human and mouse skins. Immunoprecipitation experiments showed that Sp1 and L1 could be bound in a complex. Calcium (Ca(2+)) and all-trans retinoic acid are the positive modulators of KC differentiation, which positively and negatively regulated Sp1 and L1 expression. The data suggest that coincident expression of Sp1 with L1 proteins in differentiating KCs is mediated by a calcium-dependent signaling pathway.
authors.affiliation: Diamantina Institute for Cancer Immunology and Metabolic Medicine, The University of Queensland, Research Extension, Princess Alexandra Hospital, Woolloongabba, Queensland 4102, Australia.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Zhou
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Saunders
authors.forename: Ian H
authors.initials: IH
authors.lastname: Frazer
authors.forename: Kong-Nan
authors.initials: KN
authors.lastname: Zhao
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D036022:Capsid Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism / Q000821:virology; D051379:Mice; D009856:Oncogene Proteins, Viral / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000032:analysis / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism; D015854:Up-Regulation; D014764:Viral Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D036022:Capsid Proteins; C114580:HPV L1 protein, Human papillomavirus; D009856:Oncogene Proteins, Viral; D011498:Protein Precursors; D016329:Sp1 Transcription Factor; D014764:Viral Proteins; D014212:Tretinoin; C032253:involucrin; D002118:Calcium