Rat calvarial cell lines immortalized with sv-40 large t antigen: Constitutive and retinoic acid- inducible expression of osteoblastic features

Abstract

Two new bone cell lines were established by immortalizing cells derived from embryonic rat calvariae with a recombinant retrovirus containing the cDNA for SV-40 large T antigen and the neomycin resistance gene. One cell line, RCT- 1, isolated from early digest cells, a population which typically does not express osteoblastic features, displayed osteoblastic characteristics only after 3 days of treatment with 1 μM retinoic acid: Alkaline phosphatase activity increased from 0.003 to 0.25 μmol/min  mg protein, the steady state level of type I procollagen mRNA increased 4-fold, and the cells acquired a PTH-stimulatable adenylate cyclase (EC60,10 nM). mRNA for osteopontin, an abundant bone mat..