EXPRESSION OF CLASS-I HOMEOBOX GENES IN FETAL AND ADULT MURINE SKIN

We examined the expression patterns of several class I homeobox genes in mouse fetal and adult skin. All the genes of the Hox-B locus, excep t Hoxb-1, are expressed in skin from murine fetuses of 17 and 18 d ges tation, at which time the epidermis is undergoing stratification and d ifferentiation. The amount of individual Hox gene message varies consi derably, but expression of all genes is detectable by RNase protection except Hoxb-1, which could not be detected even by the reverse transc ription-polymerase chain reaction (RT-PCR) assay. Homeobox gene expres sion in skin is not confined to the Hox-B locus; the paralogous genes Hoxa-4, -b-4, -c-4, and -d-4 are all expressed. The amount of Hoxb-4, -b-2, and -c-4 message in skin is relatively constant from the earlies t gestational day examined (day 16) through birth at day 19. Expressio n of several homeobox genes is also seen in adult skin.