Genomic instability in the type II TGF-beta1 receptor gene in atherosclerotic and restenotic vascular cells

Area of Science:

• Molecular Biology
• Genetics
• Cardiovascular Research

Background:

• Cells in human atherosclerotic lesions resist TGF-beta1's antiproliferative effects.
• TGF-beta1 is crucial for wound repair and normally inhibits cell proliferation.

Purpose of the Study:

• To investigate if microsatellite instability causes loss of the TGF-beta1 Type II receptor (TbetaR-II).
• To determine if TbetaR-II loss leads to acquired resistance to TGF-beta1 in vascular lesions.

Main Methods:

• Analysis of DNA from human atherosclerotic and restenotic lesions.
• High fidelity PCR and restriction analysis to detect deletions in the TbetaR-II A10 microsatellite.
• Sequencing to confirm mutation types and locations.

Main Results:

• Acquired 1 and 2 bp deletions were found in the TbetaR-II microsatellite within lesion DNA.
• These deletions occurred in replication error-prone regions of TbetaR-II, causing frameshift mutations.
• Microsatellites in hMSH3, hMSH6, and p53 remained unaffected, indicating specificity.
• Mutations were localized to specific lesion areas, distinct from wild-type surrounding tissue.

Conclusions:

• Microsatellite instability in TbetaR-II leads to functional loss of the receptor.
• This loss confers resistance to TGF-beta1's antiproliferative and apoptotic signals.
• Disruption of TGF-beta1 signaling via TbetaR-II instability may promote the selection of disease-prone cells in vascular lesions.