Constitutive expression of human coagulating factor IX in HeLa cells by homologous recombination of the promoter

Constitutive expression of hFIX protein in nonhepatocytes was studied. The gene targeting vector was constructed and transferred into HeLa cells. With the detection system of PCR, we demonstrated that the endogenous hFIX prom oter was replaced with an hCMV promoter when targeted insertion of the cons tructor was directed by the sequence homology. The expression of hFIX in th e modified HeLa cells, 11.2 ng/10(6) cell/24 h, strongly suggested that hFI X gene could be activated by a powerful promoter in nonhepatocytes. The res ults would make it possible to examine the feasibility of re-regulate gene expression by promoter replacement.