h3/Acidic calponin: an actin-binding protein that controls extracellular signal-regulated kinase 1/2 activity in nonmuscle cells.
Migration of fibroblasts is important in wound healing. Here, we demonstrate a role and a mechanism for h3/acidic calponin (aCaP, CNN3) in REF52.2 cell motility, a fibroblast line rich in actin filaments. We show that the actin-binding protein h3/acidic calponin associates with stress fibers in the absence of stimulation but ... is targeted to the cell cortex and podosome-like structures after stimulation with a phorbol ester, phorbol-12,13-dibutyrate (PDBu). By coimmunoprecipitation and colocalization, we show that extracellular signal-regulated kinase (ERK)1/2 and protein kinase C (PKC)alpha constitutively associate with h3/acidic calponin and are cotargeted with h3/acidic calponin in the presence of PDBu. This targeting can be blocked by a PKC inhibitor but does not require phosphorylation of h3/acidic calponin at the PKC sites S175 or T184. Knockdown of h3/acidic calponin results in a loss of PDBu-mediated ERK1/2 targeting, whereas PKCalpha targeting is unaffected. Caldesmon is an actin-binding protein that regulates actomyosin interactions and is a known substrate of ERK1/2. Both ERK1/2 activity and nonmuscle l-caldesmon phosphorylation are blocked by h3/acidic calponin knockdown. Furthermore, h3/acidic calponin knockdown inhibits REF52.2 migration in an in vitro wound healing assay. Our findings are consistent with a model whereby h3/acidic calponin controls fibroblast migration by regulation of ERK1/2-mediated l-caldesmon phosphorylation.
Mesh Terms:
Actins, Animals, Calcium-Binding Proteins, Down-Regulation, Fibroblasts, Gene Knockdown Techniques, Intracellular Space, Mice, Microfilament Proteins, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Muscles, NIH 3T3 Cells, Phorbol 12,13-Dibutyrate, Phosphorylation, Phosphoserine, Phosphothreonine, Protein Binding, Protein Kinase C-alpha, Protein Kinase Inhibitors, Protein Transport, Rats, Wound Healing
Actins, Animals, Calcium-Binding Proteins, Down-Regulation, Fibroblasts, Gene Knockdown Techniques, Intracellular Space, Mice, Microfilament Proteins, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Muscles, NIH 3T3 Cells, Phorbol 12,13-Dibutyrate, Phosphorylation, Phosphoserine, Phosphothreonine, Protein Binding, Protein Kinase C-alpha, Protein Kinase Inhibitors, Protein Transport, Rats, Wound Healing
Mol. Biol. Cell
Date: Apr. 15, 2010
PubMed ID: 20181831
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