Unbalanced RNA accumulation in regenerating mouse epidermis following abrasion

Following removal of the epidermis from the backs of CD-1 female mice, the epidermis is regenerated from the underlying resting hair follicles. The epidermis, which is normally 2 cell layers in thickness, reaches 7 cell layers by 5 days after abrasion and maintains this thickness throughout the rest of the 7-day experimental period. DNA and protein accumulate coordinately with the increase in epidermal wet weight as the regenerating epidermis thickens, reaching 3 to 4X normal levels by day 5. In contrast, RNA accumulates disproportionately, reaching levels over 12X that of normal by day 5. The unbalanced accumulation of RNA is also seen per cell since there is a 3- to 4-fold increase in the RNA/DNA ratio as well as approximately comparable increase in RNA/protein. Protein/DNA does not increase markedly during regeneration, although at days 6 and 7 it does increase slightly.