The expression of human alpha -like globin genes in transgenic mice mediated by bacterial artificial chromosome.

After screening a bacterial artificial chromosome of human genomic DNA library with human HS-40, zeta-, alpha-, and theta-globin probes, a 110-kb clone bearing the whole human alpha-globin gene cluster was obtained and rare restriction endonuclease mapping was performed. The bacterial artificial chromosome DNA was isolated, and transgenic mice were generated. Three founders were detected from 35 newborn mice. The copy numbers were 1, 2, and 2, and the expression of human alpha-globin genes in various tissues at different developmental stages in the transgenic mice was assayed. The human alpha-globin mRNA can be detected in bone marrow, kidney, liver, brain, but not in muscle, testis, or thymus. The human zeta-globin genes were switched off, and the alpha-globin genes were switched at day 11.5 in mouse embryo, indicating that developmental stage-specific expression of the alpha-like globin genes was properly regulated. The human alpha-globin mRNA ranged between 17-68% of the endogenous mouse alpha-globin, suggesting that the expression of human alpha-globin genes is integration site-dependent in transgenic mice. The ratio of human alpha(2)- and alpha(1)-globin gene expression in adult transgenic mouse is about 2.5:1 similar to the expression in human.