CellsAug 26, 2026

FHL3 Controls Changes in Blood Vessel Muscle Cells Through the MRTFB-SRF Signaling Pathway

CRISPR Gene Editing Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Aug 29, 2026

Abstract

FHL3 is identified as the top repressor of the contractile state in vascular smooth muscle cells.

Colocalization analyses connect a coronary artery disease risk allele with reduced FHL3 expression in vascular tissues.
FHL3 co-localizes with the transcriptional co-activator MRTFB, suggesting a functional interaction.
Overexpression of FHL3 decreases the induction of contractile markers driven by MRTFB and serum response factor.
Knockdown of FHL3 or overexpression of MRTFB leads to reduced proliferation and migration of vascular smooth muscle cells.
FHL3's role in inhibiting the contractile phenotype may involve interference with MRTFB-SRF signaling.

Simplified

Genome-wide association studies have uncovered many coronary artery disease (CAD) loci, but mechanisms linking risk variants to vascular biology remain unclear. We screen candidate causal CAD genes for regulators of the vascular smooth muscle cell (VSMC) contractile phenotype using a pooled CRISPR-Cas9 knockout library in primary human VSMCs with MYH11 protein levels as the readout. FHL3 (four-and-a-half LIM domains protein 3) emerges as the top repressor of the contractile state. Colocalization analyses in a VSMC biobank and vascular tissues associate a CAD risk allele with reduced FHL3 expression. Biochemical and imaging studies show FHL3 is associated and co-localizes with the transcriptional co-activator MRTFB (myocardin-related transcription factor-B). Functionally, FHL3 overexpression attenuates MRTFB-serum response factor (SRF)-driven induction of contractile markers (MYH11, transgelin), whereas FHL3 knockdown increases their expression in an MRTFB-dependent manner. FHL3 knockdown or MRTFB overexpression reduces VSMC proliferation and migration, and FHL3 overexpression mitigates MRTFB-driven effects on these behaviors. These data identify FHL3 as a regulator of VSMC plasticity that inhibits the contractile phenotype by interfering with MRTFB-SRF signaling, link a CAD-associated genetic signal to the VSMC phenotype, and nominate the FHL3-MRTFB interaction as a potential therapeutic target.

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FHL3 Controls Changes in Blood Vessel Muscle Cells Through the MRTFB-SRF Signaling Pathway

Abstract

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