title: Rescue of the transcription factors Sp1 and NFI in human skin keratinocytes through a feeder-layer-dependent suppression of the proteasome activity.
abstract: Co-culturing human skin keratinocytes along with a feeder layer has proven to considerably improve their proliferative properties by delaying massive induction of terminal differentiation. Through a yet unclear mechanism, we recently reported that irradiated 3T3 (i3T3) fibroblasts used as a feeder layer increase the nuclear content of Sp1, a positive transcription factor (TF) that plays a critical role in many cellular functions including cell proliferation, into both adult skin keratinocytes and newborn skin keratinocytes. In this study, we examined the influence of i3T3 on the expression and DNA binding of NFI, another TF important for cell proliferation and cell cycle progression, and attempted to decipher the mechanism by which the feeder layer contributes at maintaining higher levels of these TFs in skin keratinocytes. Our results indicate that co-culturing both adult skin keratinocytes and newborn skin keratinocytes along with a feeder layer dramatically increases glycosylation of NFI and may prevent it from being degraded by the proteasome.
authors.affiliation: LOEX/CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHA, Québec, QC, Canada G1S4L8.
authors.forename: Céline
authors.initials: C
authors.lastname: Duval
authors.forename: Manon
authors.initials: M
authors.lastname: Gaudreault
authors.forename: François
authors.initials: F
authors.lastname: Vigneault
authors.forename: Lydia
authors.initials: L
authors.lastname: Touzel-Deschênes
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Rochette
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Masson-Gadais
authors.forename: Lucie
authors.initials: L
authors.lastname: Germain
authors.forename: Sylvain L
authors.initials: SL
authors.lastname: Guérin
mesh_terms: D016475:3T3 Cells; D000328:Adult; D000818:Animals; D061252:Feeder Cells; D006801:Humans; D007231:Infant, Newborn; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D025542:Neurofibromin 1 / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D025542:Neurofibromin 1; D016329:Sp1 Transcription Factor; D046988:Proteasome Endopeptidase Complex