Periostin/Filamin-A: A Candidate Central Regulatory Axis for Valve Fibrogenesis and Matrix Compaction

Area of Science:

• Cardiovascular Biology
• Molecular Cell Biology
• Developmental Biology

Background:

• Heart valve development, aging, and disease involve signaling molecules modulating tissue organization.
• Periostin and filamin A (FLNA) are key proteins in developing heart valves.
• Periostin and FLNA interactions are implicated in proper valve remodeling and maturation.

Purpose of the Study:

• To investigate the cross-talk between filamin A (FLNA) and periostin signaling in postnatal heart valve remodeling.
• To elucidate the molecular mechanisms by which FLNA and periostin influence valve interstitial cell (VIC) differentiation.

Main Methods:

• Stimulation of VICs with periostin and analysis of protein interactions (Pak1, FLNA).
• Assessment of FLNA phosphorylation and Pak1 kinase activity.
• Genetic screening of patients with mitral valve prolapse for FLNA mutations and functional validation of mutants.

Main Results:

• Periostin stimulation enhances the interaction between Pak1 and FLNA in VICs.
• Pak1 phosphorylates FLNA at S2152, increasing Pak1 kinase activity and promoting VIC differentiation.
• FLNA mutations found in patients with mitral valve prolapse impair periostin-induced signaling, Pak1 activity, and VIC differentiation.

Conclusions:

• Bidirectional interaction between FLNA and Pak1, stimulated by periostin, is essential for cytoskeletal reorganization and VIC differentiation into mature valve leaflets.
• FLNA mutations disrupt this signaling pathway, contributing to abnormal heart valve development and disease.