α-Actinin-4 Is Essential for Maintaining the Spreading, Motility and Contractility of Fibroblasts
Open Access
- 11 November 2010
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 5 (11), e13921
- https://doi.org/10.1371/journal.pone.0013921
Abstract
α-Actinins cross-link actin filaments, with this cross-linking activity regulating the formation of focal adhesions, intracellular tension, and cell migration. Most non-muscle cells such as fibroblasts express two isoforms, α-actinin-1 (ACTN1) and α-actinin-4 (ACTN4). The high homology between these two isoforms would suggest redundancy of their function, but recent studies have suggested different regulatory roles. Interestingly, ACTN4 is phosphorylated upon growth factor stimulation, and this loosens its interaction with actin. Using molecular, biochemical and cellular techniques, we probed the cellular functions of ACTN4 in fibroblasts. Knockdown of ACTN4 expression in murine lung fibroblasts significantly impaired cell migration, spreading, adhesion, and proliferation. Surprisingly, knockdown of ACTN4 enhanced cellular compaction and contraction force, and increased cellular and nuclear cross-sectional area. These results, except the increased contractility, are consistent with a putative role of ACTN4 in cytokinesis. For the transcellular tension, knockdown of ACTN4 significantly increased the expression of myosin light chain 2, a element of the contractility machinery. Re-expression of wild type human ACTN4 in ACTN4 knockdown murine lung fibroblasts reverted cell spreading, cellular and nuclear cross-sectional area, and contractility back towards baseline, demonstrating that the defect was due to absence of ACTN4. These results suggest that ACTN4 is essential for maintaining normal spreading, motility, cellular and nuclear cross-sectional area, and contractility of murine lung fibroblasts by maintaining the balance between transcellular contractility and cell-substratum adhesion.Keywords
This publication has 27 references indexed in Scilit:
- Domain analysis of α-actinin reveals new aspects of its association with F-actin during cytokinesisExperimental Cell Research, 2010
- α-Actinin 1 and α-actinin 4: Contrasting roles in the survival, motility, and RhoA signaling of astrocytoma cellsExperimental Cell Research, 2010
- Phosphorylation of α-Actinin 4 upon Epidermal Growth Factor Exposure Regulates Its Interaction with ActinJournal of Biological Chemistry, 2010
- Isoform-Specific Contributions of α-Actinin to Glioma Cell MechanobiologyPLOS ONE, 2009
- Actinin-4 gene amplification in ovarian cancer: a candidate oncogene associated with poor patient prognosis and tumor chemoresistanceLaboratory Investigation, 2009
- A novel functional assessment of the differentiation of micropatterned muscle cellsJournal of Biomechanics, 2008
- Expression and Gene Amplification of Actinin-4 in Invasive Ductal Carcinoma of the PancreasClinical Cancer Research, 2008
- Actin and α-actinin orchestrate the assembly and maturation of nascent adhesions in a myosin II motor-independent mannerNature, 2008
- Growth control by intracellular tension and extracellular stiffnessTrends in Cell Biology, 2008
- α-Actinin Is Required for Tightly Regulated Remodeling of the Actin Cortical Network during CytokinesisDevelopmental Cell, 2007