Suppression of endo B cytokeratin by its antisense RNA inhibits the normal coexpression of endo A cytokeratin.

Antisense endo B cytokeratin RNA encoded by a retrovirus vector was expressed in a derivative of the F9 embryonal carcinoma cell line. Two G418-resistant clones were selected that expressed a colinear transcript containing both neomycin and antisense endo B cytokeratin sequences. Expression of a 5-fold excess of antisense endo B RNA over endogenous, retinoic acid-induced endo B RNA resulted in suppression of endo B cytokeratin protein expression. In addition, the normal induction of endo A protein, the type II cytokeratin that polymerizes with endo B, was suppressed at the RNA and protein levels. Revertant clones, which synthesize little if any neo or antisense endo B RNA, regain the ability to express the affected gene products in response to retinoic acid. These results indicate that the suppression of endo B cytokeratin protein synthesis influences the stable levels of endo A mRNA.