Changing patterns of gap junctional intercellular communication and connexin distribution in mouse epidermis and hair follicles during embryonic development

Connexins: a connection with the skin

“…These findings are consistent with an earlier report that the epidermis might be divided in many small communication compart-ments (44). Besides, several dye transfer studies in rodent and human skin established that there is no coupling between epidermal or follicular epithelium and the underlying mesenchyme, possibly due to restricted Cx expression and selective compatibility patterns, which indicates that GJIC does not participate in epidermal-dermal interactions (43,72).…”

“…Thus, the identity in the E2 domain confers the pattern of compatibility for a connexon, which in turn is the basis for a selective communication. In many tissues communication occurs within but not between physically adjacent groups of cells, which reflects the development of different communication compartments in the absence of anatomical boundaries (43)(44)(45)(46). An example for this mechanism was recently discovered in the gastrulating mouse embryo, where the endoderm-derived embryonic tissue expresses Cx43, whereas the extraembryonic trophoectoderm expresses Cx31.…”

“…GJIC in rodent skin is mediated by at least 9 different Cx species that are expressed in developmentally and differentially regulated pattern (Tables 2, 3) (58-61). Immunohistochemical studies of skin samples from rat and mouse embryos established that the onset of stratification and differentiation of the epidermis is accompanied by a switch in Cx expression (43,61). In fetal rodent skin, basal cells express mainly Cx43 and Cx45.…”

Defective Epidermal Barrier in Neonatal Mice Lacking the C-Terminal Region of Connexin43

“…How can the mutant Cx43 protein lead to the observed phenotype? During embryogenesis, the epidermal expression pattern of connexins changes (Choudhry et al, 1997), whereas Cx43 and Cx26 are coexpressed in the suprabasal and basal layers between embryonic day 12 and 15, Cx26 becomes restricted to s. granulosum, whereas Cx43 is only found in the basal and suprabasal layers from day 17 of embryogenesis onwards. This is the time when the epidermal permeability barrier begins to cover the body surface.…”

Connexin 26 regulates epidermal barrier and wound remodeling and promotes psoriasiform response

“…Unpaired connexons or hemichannels allow the cell to release second messengers (16). Normally, Cx26 is expressed in proliferative epidermis during early embryonic development and wound reepithelization but downregulated to almost undetectable levels as terminal differentiation proceeds and Klf4 is expressed (10,(17)(18)(19)(20). CX26 is one of the most highly upregulated genes in psoriatic plaques (13,14).…”