Distinctive Effects of Cytochalasin B in Chick Primary Myoblasts and Fibroblasts.
Actin-based structures play fundamental roles in cellular functions. However it remains controversial how cells cope with the absence of F-actin structures. This report focuses on short- and long-term effects of cytochalasin B (CB) on actin-complexes in fibroblasts and myoblasts. Thirty min of CB treatment dispersed subplasma actin cortices, lamellipodia, ruffled membranes, stress fibers and adhesion plaques into actin patches in fibroblasts and muscle cells. In contrast, 72 hrs CB treatment showed distinct morphological effects. Fibroblasts became giant multinucleated-finger shaped with 5 to 10 protrusions, 3-8 μm in width, and >200 μm in length. They lacked cortical actin, stress fibers, adhesion plaques and ruffled membranes but contained immense lamelliopodia with abnormal adhesion plaque protein complexes. Muscle cells transformed into multinucleated globular-shaped but contained normal I-Z-I and A-bands, indicating that CB did not interfere with the assembly of myofibrils. Within 30 min after CB removal, finger-shaped fibroblasts returned to their original shape and actin-containing structures rapidly reappeared, whereas muscle cells respond slowly to form elongated myotubes following CB washout. The capacity to grow, complete several nuclear cycles, assemble intermediate filaments and microtubules without a morphologically recognizable actin cytoskeleton raises interesting issues related to the role of the actin compartments in eukaryotic cells.
Animal Products Research Division, NARO Institute of Livestock and Grassland Science, Tsukuba, Ibaraki, 305-0901, Japan.
Koichi
K
Ojima
Department of Cell Biology, Beijing Institute for Cancer Research, Beijing Medical University, Beijing, 100083, China.
Zhong-Xiang
ZX
Lin
Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brasil.
Ivone Rosa de
IR
Andrade
Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brasil.
Manoel Luis
ML
Costa
Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brasil.
Claudia
C
Mermelstein
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D003571:Cytochalasin B / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D009210:Myofibrils / Q000378:metabolism / Q000648:ultrastructure
D000199:Actins; D003571:Cytochalasin B