Regulation of vascular smooth muscle: calponin 3 contributes to phorbol ester-induced cell contraction and is critical for cell proliferation and migration
Embargo Date
2027-05-16
OA Version
Citation
Abstract
Under physiological conditions, vascular smooth muscle cells (VSMCs) exhibit a contractile phenotype, which maintains vascular tone through contraction. In response to vascular injury, VSMCs switch to a synthetic phenotype, contributing to tissue repair through proliferation and migration. While the Ca2+-calmodulin-myosin light chain kinase pathway is the best-studied mechanism regulating vascular smooth muscle (VSM) contraction, the regulation of actin filaments (F-actin) in this process is not fully understood. Apart from cross-bridge cycling, cytoskeletal actin remodeling is also essential for VSM contraction, yet the underlying mechanisms remain unclear. Calponin 3 (CNN3), an actin-binding protein, is expressed in both non-muscle and smooth muscle tissues, whereas its function has been minimally investigated in smooth muscle. The known functions of CNN3 in other cell types are closely associated with its regulation of F-actin. This study elucidates the roles of CNN3 in regulating VSMC contraction, proliferation, and migration, processes that are contingent upon F-actin.
This study reveals that CNN3, though containing binding sites for ERK and PKC, does not interact with either protein in contractile VSMCs and has no significant effect on ERK phosphorylation, suggesting it does not function as an adaptor protein in phospho-ERK-mediated VSM contraction. During DPBA-induced VSM contraction, the binding of CNN3 to F-actin increases after 5 minutes but subsequently decreases after 10 minutes, suggesting its biphasic role in regulating the availability of F-actin. The interactions of CNN3 with three actin isoforms—alpha-smooth muscle actin (α-SMA), beta-cytoplasmic actin (β-actin), and gamma-cytoplasmic actin (γ-actin)—are characterized here. In resting VSM, CNN3 binds to all three actin isoforms. Following DPBA-induced VSM contraction, the interactions of CNN3 with all three actin isoforms undergo significant changes, with isoform-specific changes observed across different cell compartments. These findings suggest that CNN3 acts as a stabilizer of contractile actin filaments and as a regulator of cytoskeletal actin, facilitating actin cytoskeleton remodeling during VSM contraction. Furthermore, this study shows that CNN3 knockdown disrupts VSMC proliferation and migration, highlighting its role in vascular injury repair.
Characterizing CNN3’s biological functions in contractile and synthetic VSMCs broadens our knowledge of its functions in these cells and provides insights into the mechanisms underlying VSMC contraction, proliferation, and migration, thereby advancing therapeutic strategies by identifying potential targets for vascular diseases associated with impaired or abnormal VSMC functions.
Description
2025