title: Effect of cell density and growth factors on matrix GLA protein expression by normal rat kidney cells.
abstract: The present studies demonstrate that the expression of the vitamin K-dependent matrix Gla protein (MGP) is critically dependent on cell density in culture. Subculture of confluent NRK cells to 1/30 of the confluent cell density causes a 50- to 100-fold decline in MGP expression per cell within two days. MGP expression subsequently increases with increasing cell density and eventually attains a level of expression per cell at five days post-confluence that is over 2,000-fold greater than was seen in the cells two days after the 1 to 30 subculture. These reversible, density-dependent changes in MGP expression are far larger than have been previously reported for other secreted proteins and suggest that the as yet unknown function of MGP requires its expression at high cell density but not at low. We have also observed that human epidermal growth factor (EGF) causes a 20-fold reduction in MGP expression in post-confluent, non-dividing cultures and suggest that the suppression of MGP function at high density may be a prelude to cell migration or division in response to appropriate signals.
authors.affiliation: Department of Biology, University of California at San Diego, La Jolla 92093-0322, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Cancela
authors.forename: B
authors.initials: B
authors.lastname: Hu
authors.forename: P A
authors.initials: PA
authors.lastname: Price
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002450:Cell Communication / Q000502:physiology; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000494:pharmacology; D016326:Extracellular Matrix Proteins; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007668:Kidney / Q000166:cytology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014812:Vitamin K / Q000235:genetics*; D000097568:Matrix Gla Protein
chemical_list: D002135:Calcium-Binding Proteins; D004815:Epidermal Growth Factor; D016326:Extracellular Matrix Proteins; D016222:Fibroblast Growth Factor 2; D006133:Growth Substances; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D014812:Vitamin K; D000097568:Matrix Gla Protein