Repression of versican expression by microRNA-143

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Smooth muscle cells (SMCs) exhibit phenotypic plasticity, modulating smooth muscle marker expression and up-regulating extracellular matrix (ECM) components.
• Myocardin is a potent transcription factor for smooth muscle-specific genes, but its role in orchestrating ECM expression during differentiation is unclear.

Purpose of the Study:

• To investigate whether myocardin coordinates ECM expression with the smooth muscle differentiation program.
• To elucidate the role of microRNA-143 (miR-143) in myocardin-mediated regulation of ECM components, specifically versican.

Main Methods:

• Quantitative PCR to assess gene and microRNA expression.
• Luciferase reporter assays to validate microRNA targeting.
• Overexpression and depletion studies to determine the functional role of miR-143.
• Cell migration assays to assess functional consequences.

Main Results:

• Myocardin induces transcription of miR-143, which directly targets and represses versican mRNA.
• Overexpression of miR-143 significantly reduces versican expression, while its depletion increases versican levels.
• Myocardin-dependent repression of versican occurs via miR-143 induction.
• Regulation of versican by miR-143 is implicated in platelet-derived growth factor BB-induced SMC migration.

Conclusions:

• Myocardin coordinates smooth muscle differentiation by inducing miR-143, thereby attenuating ECM protein versican expression.
• This study reveals a novel mechanism by which myocardin regulates ECM production through microRNA induction during SMC differentiation.
• The miR-143-versican axis plays a role in SMC migration, highlighting its importance in vascular biology.