The stress affects the proliferation and apoptosis in keratinocytes of Balb/c mice

The skin is frequently affected by physical and chemical factors, in consequence is of clinical interest address the effect of different stressors on adaptation, proliferation and cell death of epidermal cells. Material and Methods: Skin biopsies of newborn Balb/c mice were cultured in DMEM and were UV irradiated; heated at 41°C or pulsed with 5μM HgCl 2 , 0.2% H 2 O 2 , 10% ethanol, 20μM cycloheximide or 20μM camptothecin. After that, the expression of FasR, FasL, Caspase 3, Caspase 8, DFF40, Hsp70, Ki67 and PCNA was detected in cell extracts and tissues by Western blotting, immunohistochemistry and RT‐PCR. Apoptosis was studied by TUNEL. Results: The skin of newborn Balb/c mice exhibited a high rate of cell proliferation; interestingly under stress the PCNA protein decreased and became associated with the cytoskeleton. The expression of HSP proteins was overdriven by stress, being the most important Hsp70.3.‐The FasR was homogeneously expressed in normal and stressed cells, however it was oligomerized by stress; the behavior of FasL was similar to its own receptor. The proenzymes Caspase 3, Caspase 8 and DDF40 were detected in all cell extracts, nevertheless the active forms were detected exclusively in stressed cells. The apoptotic rate was significantly increased in stressed cells. Conclusions: The stress overdrives the HSP production and the activation of proapoptotic proteins of the Fas pathway; this is concurrent with a decrease of keratinocyte proliferation.