Beta and gamma-cytoplasmic actins display distinct distribution and functional diversity.
Using newly generated monoclonal antibodies, we have compared the distribution of beta- and gamma-cytoplasmic actin in fibroblastic and epithelial cells, in which they play crucial roles during various key cellular processes. Whereas beta-actin is preferentially localized in stress fibers, circular bundles and at cell-cell contacts, suggesting a role in cell attachment and contraction, gamma-actin displays a more versatile organization, according to cell activities. In moving cells, gamma-actin is mainly organized as a meshwork in cortical and lamellipodial structures, suggesting a role in cell motility; in stationary cells, gamma-actin is also recruited into stress fibers. beta-actin-depleted cells become highly spread, display broad protrusions and reduce their stress-fiber content; by contrast, gamma-actin-depleted cells acquire a contractile phenotype with thick actin bundles and shrinked lamellar and lamellipodial structures. Moreover, beta- and gamma-actin depleted fibroblasts exhibit distinct changes in motility compared with their controls, suggesting a specific role for each isoform in cell locomotion. Our results reveal new aspects of beta- and gamma-actin organization that support their functional diversity.
Dugina
Vera
V
Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.
Zwaenepoel
Ingrid
I
Gabbiani
Giulio
G
Clément
Sophie
S
Chaponnier
Christine
C
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D002451:Cell Compartmentation; D002465:Cell Movement; D048430:Cell Shape; D003593:Cytoplasm / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D008938:Mitosis; D008954:Models, Biological; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000037:antagonists & inhibitors; D021381:Protein Transport; D011554:Pseudopodia / Q000378:metabolism; D051381:Rats; D013347:Subcellular Fractions / Q000378:metabolism; D034421:Sus scrofa
D000199:Actins; D000911:Antibodies, Monoclonal; D000205:Actomyosin; D020559:Monomeric GTP-Binding Proteins