Epidermal growth factor (EGF) affects sulphydryl and disulphide levels in cultured mouse skin: possible relationship between effects of EGF and of the tabby gene on thiols.

Studies from our laboratory have previously shown that the syndrome produced in the mouse by the X-linked gene tabby (Ta) has many features in common with human X-linked hypohidrotic ectodermal dysplasia. We have also demonstrated that tabby has abnormally elevated epidermal sulphydryl (SH): disulphide (SS) ratios, in common with an autosomal form of ectodermal dysplasia. The organs and tissues affected in many of the traits of these syndromes are targets of epidermal growth factor (EGF) and we have shown that the EGF-producing cells are deficient in tabby. In the present study we examined whether EGF affects SH and SS levels in normal mouse skin in tissue culture, and we report here that it does. EGF at a concentration of 25 ng/mL tissue culture medium lowers SH levels as compared with controls (0 ng/mL) in the epidermal layers examined (stratum malpighii of the tail and stratum malpighii and stratum corneum of flank skin). In general, other concentrations of EGF increase epidermal SH levels, although very high doses also reduce them. EGF at 25 ng/mL also lowers total SH + SS concentrations in the epidermal layers. Fetuses hemizygous for the Ta gene appear to have higher total SH + SS epidermal concentrations than their wild-type control littermates. These data, taken together with some of our previous findings, suggest the possibility that a relationship may exist between Ta, EGF, and thiol concentrations. Further study is required to elucidate this relationship.