Formation of Hirano bodies in Dictyostelium and mammalian cells induced by expression of a modified form of an actin-crosslinking protein.
We report the serendipitous development of the first cultured cell models of Hirano bodies. Myc-epitope-tagged forms of the 34 kDa actin bundling protein (amino acids 1-295) and the CT fragment (amino acids 124-295) of the 34 kDa protein that exhibits activated actin binding and calcium-insensitive actin filament crosslinking activity were expressed in Dictyostelium and mammalian cells to assess the behavior of these modified forms in vivo. Dictyostelium cells expressing the CT-myc fragment: (1) form ellipsoidal regions that contain ordered assemblies of F-actin, CT-myc, myosin II, cofilin and alpha-actinin; (2) grow and develop more slowly than wildtype, but produce normal morphogenetic structures; (3) perform pinocytosis and phagocytosis normally; and (4) produce a level of total actin equivalent to wildtype, but a higher level of F-actin. The paracrystalline inclusions bear a striking resemblance to Hirano bodies, which are associated with a number of pathological conditions. Furthermore, expression of the CT fragment in murine L cells results in F-actin rearrangements characterized by loss of stress fibers, accumulation of numerous punctate foci, and large perinuclear aggregates, the Hirano bodies. Thus, failure to regulate the activity and/or affinity of an actin crosslinking protein can provide a signal for formation of Hirano bodies. More generally, formation of Hirano bodies is a cellular response to or a consequence of aberrant function of the actin cytoskeleton. The results reveal that formation of Hirano bodies is not necessarily related to cell death. These cultured cell models should facilitate studies of the biochemistry, genetics and physiological effects of Hirano bodies.
Maselli
Andrew G
AG
Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
Davis
Richard
R
Furukawa
Ruth
R
Fechheimer
Marcus
M
D000199:Actins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002478:Cells, Cultured; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D004195:Disease Models, Animal; D004705:Endocytosis / Q000235:genetics; D000939:Epitopes / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors / Q000235:genetics; D002479:Inclusion Bodies / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008970:Molecular Weight; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D000199:Actins; D000939:Epitopes; D008840:Microfilament Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins