Figure 4.

Ablation of miR-205 compromises the proliferation of interfollicular progenitors. (a) Ablation of miR-205 results in a marked decline in S-phase cells that incorporate BrdU in the basal epidermis. Values are mean ± s.d. from five independent experiments; ***, P < 0.001 by Student’s t-test. (b) The KO skin shows shortened distance between HFs, an indication of less proliferative epidermis. White arrows measure the distance between adjacent HFs. (c) miR-205 KO interfollicular progenitors prematurely exit the cell cycle, as indicated by significantly decreased Ki67+ cells in the basal epidermis. White dotted lines mark the epidermal/dermal boundary; arrowheads indicate K5+/Ki67− interfollicular progenitors. Data shown are mean ± s.d. from five independent experiments; ***, P < 0.001 by Student’s t-test. (d) In situ hybridization confirms the complete loss of miR-205 in the grafted KO skin. (e) Fifteen days after grafting onto nude mice, the miR-205 KO epidermis is much less proliferative as indicated by less Ki67+ interfollicular progenitors and thinner epidermis. Data shown are mean ± s.d. from five independent experiments; ***, P < 0.001 by Student’s t-test. (f) miR-205 KO primary epidermal keratinocytes show a significant reduction in the formation of large holoclones in vitro. Data shown are mean ± s.d. from five independent experiments. *, P < 0.05; **, P < 0.01 by Student’s t-test. Scale bar is 100 μm in b and 20 μm in c, d and e.