KAWAHARA Akira Hiroshima Univ., Fac.of Integr.Arts Sci., Assoc.Prof., 総合科学部, 助教授 (50112157)
AMANO Minoru Hiroshima Institute of Technology, Fac.of Environmental Sci., Prof., 環境学部, 教授 (00076986)
|Budget Amount *help
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1993: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1992: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1991: ¥1,500,000 (Direct Cost: ¥1,500,000)
In the chick embryo, there is a population of chondrogenic fibroblasts known as scleral fibroblasts. Scleral fibroblasts in primary culture secrete multiple autocrine growth-promoting factors, scleral autocrine factors (SAFs), into protein-free medium. One such factor, SAF-IIa, which is heat-labile and binds to heparin, shows strong DNA synthesis-promoting activity on the mouse fibroblast cell line, BALB/c 3T3 A31 cells and has a molecular weight of ca. 16kDa by gel filtration. These data suggest that SAF-IIa is related to growth factors of the FGF family. However, the effects of heparin augumentation on the growth-promoting activity suggest that SAF-IIa is not identical to aFGF or bFGF, when assayd on scleral fibroblasts and also on BALB/c 3T3 A31 cells. The other heat-labile autocrine growth-promoting factor, SAF-IIb, shows weak binding to heparin and no growth-promoting activity for BALB/c 3T3 A31 cells. The heatresistant growth factor, SAF-I, is effective in enhancing the proliferation of BALB/c 3T3 cells and its activity is increased by heat treatment. Whole-embryo fibroblasts, which show low autocrine growth in protein-free medium, produce mainly SAF-IIa-like growth-promoting activity and do not produce SAF-I.This indicates that the strong proliferative activity of scleral fibroblasts in vitro can be attributed to the production of a strong and stable autocrine factor, SAF-I, in the growing phase and is a specialized property of the chondrogenic cells of the sclera.