Saint Francis University

About: Saint Francis University is a education organization based out in Loretto, Pennsylvania, United States. It is known for research contribution in the topics: Population & Osteoblast. The organization has 1694 authors who have published 2038 publications receiving 87149 citations.

Basic fibroblast growth factor destabilizes osteonectin mRNA in osteoblasts

Abstract: Osteonectin (secreted protein acidic and rich in cysteine, 40-kDa basement membrane) is a glycoprotein abundantly expressed in bone and in other tissues undergoing active remodeling. Fibroblast growth factors (FGFs) are important in skeletal development and fracture repair, events associated with extracellular matrix remodeling. We used the murine osteoblastic cell line MC3T3 to determine whether basic FGF (bFGF) regulates osteonectin expression in bone. Northern blot analysis showed that bFGF decreased osteonectin transcripts in a dose- and time-dependent manner. This regulation was independent of the mitogenic effect of bFGF but was dependent on new protein synthesis. Immunoprecipitation of [35S]methionine-cysteine osteoblast-conditioned medium and cell layer proteins showed that bFGF decreased osteonectin synthesis. Nuclear runoff assays failed to reveal regulation of osteonectin gene transcription by bFGF. However, bFGF dramatically decreased the stability of osteonectin mRNA in transcriptionally arrested osteoblasts. This destabilization of osteonectin mRNA may be one means by which bFGF regulates extracellular matrix remodeling.

Regulation of insulin-like growth factor I transcription by prostaglandin E2 in osteoblast cells

Abstract: Insulin-like growth factor I (IGF-I) is a widely expressed abundant autocrine and paracrine factor that regulates the proliferation and differentiation of a variety of cell types. Prostaglandin E2 (PGE2) is a potent stimulator of IGF-I synthesis in bone. We examined the regulation of IGF-I synthesis by PGE2 in osteoblast-enriched (Ob) cells from fetal rat calvaria. PGE2 treatment of Ob cells at 1 microM for 2 h resulted in a 5-fold increase in heterogeneous nuclear RNA levels, as measured by a reverse transcriptase-polymerase chain reaction assay, suggesting an increase in IGF-I gene transcription. RNase protection analysis was used to map the transcriptional start sites in the IGF-I gene that are used in Ob cells. Consistent with other extrahepatic tissues, initiation of transcription occurs primarily at three sites within the 5'-regions of exon 1 of the IGF-I gene. PGE2 treatment did not alter start site usage. The regions upstream of these transcriptional start sites were analyzed by transiently transf...