Related Experiment Videos
TGF-beta isoforms differentially attenuate EGF mitogenicity and receptor activity in fetal lung mesenchymal cells
1Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, USA.
Abstract:
To evaluate signaling interactions, combinations of epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) isoforms were applied to primary fetal mouse lung mesenchymal cells isolated at 16 days of gestation. The three isoforms of TGF-beta had similar mitogenic potentials, as assessed by thymidine incorporation (half-maximal effective concentration approximately 2 ng/ml). However, combined exposure to EGF and TGF-beta yielded an isoform-dependent attenuation of EGF-induced mitogenesis. Combinations of 20 ng/ml EGF and 2 ng TGF-beta 1, TGF-beta 2, or TGF-beta 3 resulted in thymidine incorporation values 0.76, 0.74, and 0.86 times that of EGF alone, respectively; attenuation of EGF mitogenicity, interactions between EGF and TGF-beta isoforms, and differences between isoforms were all statistically significant by analysis of variance. Treatment with TGF-beta isoforms significantly reduced EGF-induced receptor angiotensin II substrate phosphorylation. TGF-beta isoform-specific signaling also significantly attenuated EGF-induced phosphorylation of the mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase 2. These results suggest that isoform-specific TGF-beta signaling modulates the EGF signal transduction pathway upstream of MAP kinase.
Insights
Transforming growth factor-beta (TGF-beta) isoforms can reduce epidermal growth factor (EGF)-induced cell growth. This study shows TGF-beta isoform-specific signaling modulates EGF pathways upstream of mitogen-activated protein kinase.
Area of Science:
- Cell signaling
- Molecular biology
- Developmental biology
Background:
- Epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) are key regulators of cell growth and differentiation.
- TGF-beta exists in three isoforms (TGF-beta 1, TGF-beta 2, TGF-beta 3) with potentially distinct biological functions.
- Understanding the interplay between EGF and TGF-beta signaling is crucial for comprehending lung development and tissue repair.
Purpose of the Study:
- To investigate the signaling interactions between EGF and different TGF-beta isoforms.
- To determine how combined EGF and TGF-beta stimulation affects cell proliferation (mitogenesis).
- To elucidate the molecular mechanisms underlying these interactions, focusing on signal transduction pathways.
Main Methods:
- Primary fetal mouse lung mesenchymal cells (gestation day 16) were treated with EGF and TGF-beta isoforms.
- Cell proliferation was assessed by measuring thymidine incorporation.
- Protein phosphorylation, including receptor and mitogen-activated protein (MAP) kinase (extracellular signal-regulated kinase 2) phosphorylation, was analyzed.
Main Results:
- All three TGF-beta isoforms exhibited similar mitogenic potentials.
- Combined EGF and TGF-beta treatment resulted in an isoform-dependent attenuation of EGF-induced mitogenesis.
- TGF-beta isoforms significantly reduced EGF-induced phosphorylation of the EGF receptor and extracellular signal-regulated kinase 2.
Conclusions:
- Isoform-specific TGF-beta signaling significantly modulates EGF-induced mitogenesis.
- TGF-beta acts upstream of MAP kinase, interfering with EGF signal transduction.
- These findings highlight the complexity of growth factor interactions in regulating cellular responses.