DIFFERENTIAL IN-VITRO RESPONSES OF ELASTIN EXPRESSION TO BASIC FIBROBLAST GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-BETA-1 IN UPPER, MIDDLE AND LOWER DERMAL FIBROBLASTS

Elastin mRNA levels were measured in cultured skin fibroblasts derived from upper, middle and lower dermal layers. The elastin mRNA levels w ere highest in the fibroblasts from the upper dermal layer and lowest in the lower dermal fibroblasts. Modulation of elastin expression by b asic fibroblast growth factor and transforming growth factor pi in the dermal fibroblasts was also studied. Basic fibroblasts growth factor downregulated elastin expression in the upper dermal fibroblasts but d id not significantly change elastin expression in the middle and lower dermal fibroblasts. Upregulation of elastin expression by transformin g growth factor pi was greater in the upper dermal fibroblasts than in the middle and lower dermal fibroblasts. Platelet-derived growth fact or induced no significant changes in the three types of dermal fibrobl asts. The results suggest that the differential responses of elastin e xpression to potent modulators may be at least partially responsible f or the abnormal elastin metabolism specifically observed in the upper dermal layer.