Differential effects of transforming growth factors beta 1, beta 2, beta 3 and beta 5 on chondrogenesis in mouse limb bud mesenchymal cells.
The present study was performed to determine whether mammalian TGF-beta isoforms and Xenopus TGF-beta 5 elicit a differential chondrogenic response on mesenchymal cells during mouse limb development. Results showed that TGF-beta isoforms produced a distinct chondrogenic pattern depending on embryonic stage. When they were applied to 5 day micromass cultures of limb mesenchymal cells from embryonic stages 19, 20 and 21, a differential response to all four TGF-beta isoforms assayed was observed. By stage 19 the cells formed a uniform sheet of cartilage cells; by stage 20, mesenchymal cells were more responsive to TGF-beta 1 and TGF-beta 5 than at stages 19 and 21, showing an entire cell layer of chondrogenic cells with higher accumulation of extracellular matrix. The diminished effect of TGF-beta 2 and TGF-beta 3 at stages 20 and 21 was accompanied by a nodular pattern of chondrogenic cells rather than by a uniform sheet, as seen at stage 19. At stage 20 TGF-beta 1 and TGF-beta 5 enhanced the expression of sulfated proteoglycans, type II collagen, cartilage link protein and alkaline phosphatase activity. In contrast, TGF-beta 2 and TGF-beta 3 caused less expression in the same parameters. Only a transient exposure to TGF-beta isoforms at days 1 and 2 of culture stimulate chondrogenesis, indicating that TGF-beta isoforms could regulate chondrogenesis at early stages of chondrocyte differentiation. However, when TGF-beta isoforms were applied to low density cultures of mesenchymal cells, chondrogenesis was enhanced only by 25%, suggesting that TGF-beta isoforms enhanced cartilage differentiation to higher levels in micromass cultures than in situations in which little or no chondrogenic differentiation normally occurs.
Chimal-Monroy
J
J
Department of Cell Biology, UNAM, Mexico D.F., Mexico.
Díaz de León
L
L
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002356:Cartilage / Q000196:embryology*; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins; D005121:Extremities / Q000196:embryology*; D005260:Female; D005865:Gestational Age; D008297:Male; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D011506:Proteins / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000502:physiology*; D014982:Xenopus laevis; D000099249:Proteoglycan Link Protein
D000469:Alkaline Phosphatase; D003094:Collagen; D016326:Extracellular Matrix Proteins; D011506:Proteins; D011509:Proteoglycans; D013431:Sulfates; D016212:Transforming Growth Factor beta; D000099249:Proteoglycan Link Protein