Gremlin promotes vascular smooth muscle cell proliferation and migration

Area of Science:

• Vascular Biology
• Cell Signaling
• Molecular Biology

Background:

• Bone morphogenetic proteins (BMPs) are increasingly recognized for their roles in vascular health.
• Gremlin, a BMP antagonist, has an uncharacterized function in vascular smooth muscle cells (VSMCs).

Purpose of the Study:

• To investigate the expression pattern and functional role of gremlin in VSMCs.
• To determine gremlin's impact on VSMC proliferation, migration, and cell cycle.
• To explore gremlin's regulation by vasoactive factors and in response to vascular injury.

Main Methods:

• Detection of gremlin mRNA in rat aortic and carotid VSMCs.
• In vitro studies using A7r5 cells with gremlin overexpression or gene silencing.
• Analysis of cell proliferation, DNA synthesis, cell cycle progression, and migration.
• In vivo assessment of gremlin expression in balloon-injured rat carotid arteries.

Main Results:

• Gremlin mRNA is constitutively expressed in VSMCs and regulated by angiotensin II, TGF-beta1, and PDGF.
• Gremlin overexpression inhibited BMP signaling, reduced BMP-induced suppression of DNA synthesis, and increased VSMC proliferation, cell cycle progression (via p27(kip1) downregulation), and migration.
• Gremlin gene silencing inhibited VSMC proliferation and migration.
• Gremlin protein expression was elevated in the neointima of injured carotid arteries.

Conclusions:

• Gremlin is constitutively expressed in the vasculature and promotes VSMC proliferation and migration.
• Gremlin expression is modulated by growth factors and vascular injury.
• Gremlin may contribute to pathological phenotypic changes in adult VSMCs.