Interleukin-1 regulates FGF-2 mRNA and localization of FGF-2 protein in human osteoblasts

Interleukin-1 (IL-1) and basic fibroblast growth factor (FGF-2) are potent stimulators of osteoclast formation. However, the role of FGF-2 in the resp onses to IL-1 in bone has not been reported. We examined the effect of IL-1 on FGF-2 mRNA and protein expression in human osteosarcoma MG-63 osteoblas ts, normal human osteoblasts (NHOB), and osteoblasts from osteoarthritic pa tients (F2 and F13). IL-1 increased FGF-2 mRNA expression in osteoblasts wi thin 1.5 to 3 h. Multiple FGF-2 protein isoforms were expressed in human os teoblasts. Twenty-four hours of treatment of MG-63 and NHOB cells with IL-1 increased the high-molecular-weight (HMW, 22/24 kDa) and low-molecular-wei ght (LMW, IS kDa) FGF-2 proteins intracellularly. In contrast, IL-1 prefere ntially increased the LMW protein signal intracellularly as well as on the cell surface of F2 and F13 osteoblasts. We conclude that IL-1 is a major st imulator of FGF-2 expression in human osteoblasts. Furthermore, selective i ncreases in the exportable LMW protein in osteoblasts from osteoarthritic p atients may be of clinical relevance. (C) 2001 Academic Press.