Cofilin is a Component of Intranuclear and Cytoplasmic Actin Rods Induced in Cultured Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 84; no. 15; pp. 5262 - 5266
• Main Authors: Nishida, Eisuke, Iida, Kazuko, Yonezawa, Naoto, Koyasu, Shigeo, Yahara, Ichiro, Sakai, Hikoichi
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.08.1987; National Acad Sciences
• Subjects: Actin Depolymerizing Factors; Actins; Actins - analysis; Actins - metabolism; Analytical, structural and metabolic biochemistry; Animals; Antibodies; Binding and carrier proteins; Binding, Competitive; Biological and medical sciences; Carrier Proteins - analysis; Cells; Cells, Cultured; Cultured cells; Cytoplasm - ultrastructure; Dimethyl Sulfoxide - pharmacology; Fibroblasts - ultrastructure; Fluorescent antibody techniques; Fundamental and applied biological sciences. Psychology; Gels; Gelsolin; Hot Temperature; Mice; Microfilament Proteins; Molecular Weight; Molecules; Nerve Tissue Proteins - analysis; Nerve Tissue Proteins - metabolism; Phalloidine - metabolism; Proteins; Stress fibers; Cell culture; Binding protein; Vertebrata; Mammalia; Mouse; Animal; Cell nucleus; Rodentia; Actins; Fibroblast; Cytoplasm; Stress
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.84.15.5262

Incubation of cultured cells under specific conditions induces a dramatic change in the actin organization: induction of intranuclear and/or cytoplasmic actin rods (actin paracrystal-like intracellular structures). We have found that cofilin, a 21-kDa actin-binding protein, is a component of these rods. Antibodies directed against cofilin labeled intranuclear actin rods induced in cells treated with dimethyl sulfoxide or exposed to heat shock and also labeled cytoplasmic actin rods induced in cells incubated in specific salt buffers. Moreover, we found that these actin rods are not stained with fluorescent phalloidin derivatives at all and appear to be right-handed helices, different from straight bundles of F-actin such as stress fibers. In vitro experiments revealed that cofilin and phalloidin compete with each other for binding to F-actin. Since cofilin and phalloidin have the ability to stoichiometrically bind actin molecule in the filament in vitro, the above results seem to suggest that cofilin directly binds to actin molecule in nearly an equimolar ratio in these rods. We call these rods ``actin/cofilin rods.''