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A dominant-negative receptor for type beta transforming growth factors created by deletion of the kinase domain
T Brand1, W R MacLellan, M D Schneider
1Department of Medicine, Baylor College of Medicine, Houston, Texas 77030.
Abstract:
To prove the postulated role of type beta transforming growth factors (TGF beta) in cardiac development and other events, specific inhibitors of TGF beta signal transduction are needed. We truncated the type II TGF beta receptor cDNA (delta kT beta RII), to delete the predicted serine/threonine kinase cytoplasmic domain. delta kT beta RII was co-transfected into neonatal cardiac myocytes, together with reporter constructs for two cardiac-restricted genes that are regulated antithetically by TGF beta. delta kT beta RII impaired activation of the skeletal alpha-actin promoter by TGF beta 1, -2, and -3 and, conversely, impaired TGF beta inhibition of alpha-myosin heavy chain transcription. Thus, a kinase-defective T beta RII blocks signaling by all three mammalian TGF beta isoforms, and can disrupt both positive and negative control of transcription by TGF beta.
Insights
Researchers developed a kinase-defective type II TGF beta receptor (delta kT beta RII) to inhibit TGF beta signaling. This inhibitor blocked both activation and repression of cardiac gene transcription by TGF beta isoforms.
Area of Science:
- Molecular Biology
- Cardiovascular Research
- Cell Signaling
Background:
- Transforming growth factors beta (TGF beta) are crucial for cardiac development.
- Specific inhibitors are needed to elucidate TGF beta's precise roles.
- Understanding TGF beta signaling is key to cardiac research.
Purpose of the Study:
- To create a functional inhibitor of TGF beta signal transduction.
- To investigate the role of TGF beta signaling in cardiac gene regulation.
Main Methods:
- Truncation of type II TGF beta receptor cDNA to yield a kinase-defective mutant (delta kT beta RII).
- Co-transfection of delta kT beta RII with reporter constructs into neonatal cardiac myocytes.
- Assessment of TGF beta's effect on skeletal alpha-actin and alpha-myosin heavy chain gene promoters.
Main Results:
- The kinase-defective delta kT beta RII impaired TGF beta 1, -2, and -3 activation of the skeletal alpha-actin promoter.
- delta kT beta RII also inhibited TGF beta's repression of alpha-myosin heavy chain transcription.
- These findings demonstrate delta kT beta RII's efficacy against all three mammalian TGF beta isoforms.
Conclusions:
- A kinase-defective type II TGF beta receptor effectively blocks TGF beta signaling.
- This inhibitor disrupts both positive and negative transcriptional control by TGF beta.
- This tool is valuable for studying TGF beta's functions in cardiac development and other processes.