Gap-Junctional Protein Connexin 43 Is Expressed in Dermis and Epidermis of Human Skin: Differential Modulation by Retinoids

Connexins: a connection with the skin

“…These findings contrast the distinct expression pattern in mouse and rat epidermis, where Cx43 is restricted to basal cells and less differentiated lower spinous cell layers and Cx26 to terminally differentiating spinous and granular cell layers (61,70,80). However, a similar increase and co-expression of Cx26 and Cx43 has been observed when rodent or human epidermis was treated with all-trans retinoic acid or phorbol esters (64,78,81,82). Likewise, analysis of the effect of skin tumor promotors on Cx43, Cx26, and Cx31.1 in Sencar 83 mouse epidermis revealed an induction of Cx26 expression, transiently increased expression of Cx43, and significantly inhibited expression of Cx31.1 (83).…”

“…Cx37 is found throughout the epidermal layers, and Cx43 and Cx26 are co-expressed in the periderm. Rodent hair follicles and sebaceous glands express Cx43, Cx40, and Cx31, while Cx37, Cx40, and Cx43 predominate in the cutaneous microvascular and smooth muscle system, and Cx43 in dermal fibroblasts (62)(63)(64)(65)(66)(67). In addition to the Cxs mentioned above, Northern blot analyses suggest that Cx30, a close homologue of Cx26, and the recently cloned Cx57 are expressed in rodent skin, although their tissue distribution remains to be elucidated (47,68).…”

Long-term connexin-mediated bystander effect in highly tumorigenic human cells in vivo in herpes simplex virus thymidine kinase/ganciclovir gene therapy

“…It is probable that the bystander effect would have been stronger in immune-competent mice, since immune response has been proposed to be an important component of the bystander effect in vivo. 9 Enhancing the cell-cell communication capacity by treating tumors with agents such as cyclic AMP 28 or retinoids 29 might also increase the connexin-mediated bystander effect. Recently, enhancement of the bystander effect on killing of mouse mesothelioma cells by GCV in vivo by treating mice with retinoic acids was correlated with increased Cx43 expression and GJIC capacity in vitro.…”

In Vivo Modulation of Connexins 43 and 26 of Human Epidermis by Topical Retinoic Acid Treatment

“…Junctional communications could mediate the biological effects of this natural messenger, because previous studies on primary human keratinocytes and derived cell lines have documented that exposure to RA involves changes in cell-to-cell coupling (Rogers et al 1990;Salomon et al 1992), in the number and size of gap junctions (Prutkin 1975;Elias et al 1980), and in the expression of at least one of their constitutive connexin (Cx) proteins (Guo et al 1992).…”

“…Cx43 is abundantly expressed within the interfollicular epidermis (Guo et al 1992;Wingelbus et al 1992;Salomon et al 1994), whereas Cx43 and Cx26 have been shown to be variably distributed within skin adnexae (Salomon et al 1994). This distinct and partially overlapping distribution is believed to impart specific characteristics to the gap junctions of different skin regions, which presumably account for the differential patterns of communications that are observed between different subsets of human keratinocytes (Salomon et al 1988;Kam and Hodgins, 1992).…”