Figure 8 : Nuclear localization of p21 and p27 is coincident with a lack of cell cycle progression in M. musculus.

From: Comparative analysis of ear-hole closure identifies epimorphic regeneration as a discrete trait in mammals

Figure 8

(ad) Per cent positive cells (of total counted) for cell cycle markers (a) Ki67—cell cycle re-entry, (b) pRb—G1/S transition, (c) EdU—active DNA synthesis and (d) pHH3—mitotic cells (blue and red arrows). (a) Per cent Ki67+ mesenchymal cells are not different between M. musculus and A. cahirinus at D10, D15 and D20 (n=5 biological replicates for all time points except D10 and D15, A. cahirinus n=4). (b) Per cent pRb+ mesenchymal cells are greater in A. cahirinus at all time points (n=3 biological replicates for both species at each time point). (c) Active DNA synthesis is maintained during regeneration in A. cahirinus, whereas the number of EdU+ cells in M. musculus continually declines to <1% at D20 (D10, n=5 both species; D15, A. cahrinus n=5, M. musculus n=2; D20, A. cahirinus n=3, M. musculus n=3). (d) Per cent pHH3+ cells increase in A. cahirinus during regeneration, while pHH3+ cells decline in M. musculus with few detected at D20 (n=3 for all time points except D20, M. musculus n=2). Data represented as mean and s.e.m., NS (not significant) and # denote P>0.05 or P<0.05, respectively, for one-way ANOVA for species effect; P>0.05 for all comparisons for effect of day (ad). (e,f) Nuclear localization of p21 is coincident with lack of cell cycle progression. (e) Cytoplasmic p21 localization corresponds to highly proliferative epidermal cells in M. musculus, whereas nuclear staining is observed in mesenchymal cells at D15 (f). The reverse is true in A. cahirinus. Nuclear localization is evident in epidermal cells of the non-proliferative wound epidermis, while mesenchymal cells do not exhibit nuclear staining. (g) Per cent total p21 positive nuclei in the mesenchyme of M. musculus and A. cahirinus (n=3 for all time points). (h) Immunostaining for p27 shows positive nuclear staining in M. musculus mesenchymal cells (i). Cells in the blastemal region of A. cahirinus are negative for nuclear p27. (j) Quantification of per cent total p27 nuclear staining in the mesenchyme of A. cahirinus and M. musculus (n=3 biological replicates for all time points). See Supplementary Fig. 9 for positive controls (f,i).