SMOOTH-MUSCLE ALPHA-ACTIN DOWN-REGULATION IN CULTURED CHICK AORTIC SMOOTH-MUSCLE AND NEURAL CREST CELLS IS ASSOCIATED WITH ALTERED CELL-SHAPE

A modified CXL retrovirus was used to clone an antisense smooth muscle alpha-actin ribozyme sequence adjacent to the reporter lacZ sequence. The virus was applied to downregulate alpha-actin expression in cultu red smooth muscle cells obtained from chicken aortic arch and cultured neural crest cells. After infection with the ribozyme-containing CXL retrovirus both the smooth muscle and neural crest cells showed beta-g alactosidase activity accompanied by a reduction of smooth muscle alph a-actin-positive fibers. Double staining of beta-galactosidase and smo oth muscle alpha-actin using immunohistochemistry revealed that single cells infected with the CXL/ribozyme showed little to no smooth muscl e alpha-actin protein. The absence of smooth muscle alpha-actin was as sociated with a distinct change in cellular morphology of the cultured cells, suggesting that expression of smooth muscle alpha-actin in cul tured neural crest cells may be associated with cytoskeletal elements rather than vascular smooth muscle phenotype. (C) 1996 Academic Press, Inc.