The Caenorhabditis elegans unc-78 Gene Encodes a Homologue of Actin-Interacting Protein 1 Required for Organized Assembly of Muscle Actin Filaments

• Type of Material: Article
• Authors: Shoichiro Ono, Emory University
• Language: English
• Date: 2001-03-19
• Publisher: Rockefeller University Press
• Publication Version: Final Published Version
• Copyright Statement: © 2001 The Rockefeller University Press
• License: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International
• Final Published Version (URL): http://jcb.rupress.org/content/152/6/1313.full
• Title of Journal or Parent Work: Journal of Cell Biology
• ISSN: 0021-9525
• Volume: 152
• Issue: 6
• Start Page: 1313
• End Page: 1320
• Grant/Funding Information: This work was supported by grants from the American Heart Association to S. Ono.
• Keywords: AIP1; ADF/cofilin; myofibrils; WD repeats; actin filament dynamics
• Research Categories: Health Sciences, Pathology

Abstract

Assembly and maintenance of myofibrils require dynamic regulation of the actin cytoskeleton. In Caenorhabditis elegans, UNC-60B, a muscle-specific actin depolymerizing factor (ADF)/cofilin isoform, is required for proper actin filament assembly in body wall muscle (Ono, S., D.L. Baillie, and G.M. Benian. 1999. J. Cell Biol. 145:491–502). Here, I show that UNC-78 is a homologue of actin-interacting protein 1 (AIP1) and functions as a novel regulator of actin organization in myofibrils. In unc-78 mutants, the striated organization of actin filaments is disrupted, and large actin aggregates are formed in the body wall muscle cells, resulting in defects in their motility. Point mutations in unc-78 alleles change conserved residues within different WD repeats of the UNC-78 protein and cause less severe phenotypes than a deletion allele, suggesting that these mutations partially impair the function of UNC-78. UNC-60B is normally localized in the diffuse cytoplasm and to the myofibrils in wild type but mislocalized to the actin aggregates in unc-78 mutants. Similar Unc-78 phenotypes are observed in both embryonic and adult muscles. Thus, AIP1 is an important regulator of actin filament organization and localization of ADF/cofilin during development of myofibrils.