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Differential effects of transforming growth factors beta 1, beta 2, beta 3 and beta 5 on chondrogenesis in mouse limb
J Chimal-Monroy1, L Díaz de León
1Department of Cell Biology, UNAM, Mexico D.F., Mexico.
Abstract:
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.
Insights
Transforming growth factor-beta (TGF-β) isoforms differentially regulate chondrogenesis in mouse limb development. TGF-β1 and TGF-β5 show enhanced cartilage formation, particularly at embryonic stage 20.
Area of Science:
- Developmental Biology
- Cell Biology
- Biochemistry
Background:
- Mesenchymal stem cells (MSCs) differentiate into chondrocytes during limb development.
- Transforming growth factor-beta (TGF-β) signaling pathways are crucial for chondrogenesis.
- Different TGF-β isoforms may play distinct roles in regulating chondrogenic differentiation.
Purpose of the Study:
- To investigate the differential chondrogenic responses of mouse limb mesenchymal cells to mammalian TGF-β isoforms and Xenopus TGF-β5.
- To determine the influence of embryonic developmental stage on TGF-β-mediated chondrogenesis.
- To compare the effects of TGF-β isoforms in micromass versus low-density cell cultures.
Main Methods:
- Micromass cultures of mouse limb mesenchymal cells from embryonic stages 19, 20, and 21 were treated with TGF-β isoforms.
- Low-density cultures were also used to assess TGF-β effects.
- Chondrogenic markers including sulfated proteoglycans, type II collagen, cartilage link protein, and alkaline phosphatase activity were analyzed.
Main Results:
- TGF-β isoforms elicited stage-dependent chondrogenic patterns.
- TGF-β1 and TGF-β5 significantly enhanced chondrogenesis and extracellular matrix accumulation at stage 20.
- TGF-β2 and TGF-β3 showed diminished effects and induced nodular patterns at later stages.
- Transient exposure to TGF-β isoforms at early culture days stimulated chondrogenesis.
- Micromass cultures showed higher TGF-β-induced chondrogenesis compared to low-density cultures.
Conclusions:
- Mammalian TGF-β isoforms and Xenopus TGF-β5 exhibit distinct chondrogenic activities during mouse limb development.
- TGF-β isoforms regulate chondrogenesis primarily during early stages of chondrocyte differentiation.
- The cellular microenvironment, such as in micromass cultures, potentiates TGF-β-mediated cartilage differentiation.