Action of general and α-smooth muscle-specific actin antibody microinjection on stress fibers of cultured smooth muscle cells


Arterial smooth muscle cells express α- and γ-smooth muscle, as well as β- and γ-cytoplasmic actins. Two actin antibodies, one recognizing smooth muscle and cytoplasmic actin isoforms, the other recognizing specifically α-smooth muscle actin, were microinjected into cultured aortic smooth muscle cells. The effect of these antibodies on stress fiber organization was examined by staining with rhodamine-labeled phalloidin and by immunofluorescence with the same antibodies. Microinjection of the general actin antibody abolished most of the stress fiber staining with all reagents, but did not significantly affect the shape of the injected cells. This suggests that stress fiber integrity is not absolutely necessary for the maintenance of cell shape within the time of observation. Microinjection of the specific α-smooth muscle antibody abolished to various extents the staining of stress fibers with this antibody, but left practically intact their staining with rhodamine-labeled phalloidin and with the general actin antibody. This suggests that the incorporation of α-smooth muscle actin is not absolutely necessary for the maintenance of stress fiber integrity in cultured smooth muscle cells. © 1990.

Publication Title

Experimental Cell Research