Analyze The Expression And Significant Of Caspase-3、Bax、Bcl-2and Beclin-1in Epidermal Keratinocytes Of Chronic UV-damaged Mice

With the acute changes of environment,people is under threat from chronic UV-damage.The changes in skin appearance which caused by chronic UV-damage.Such as increased wrinkle formation,reduced recoil capacity,increased pidment.In recent years, more and more scholars research on chronic UV-damage.But the relationship with apoptosis and autophagy is not clear.Objective To establish and perfect the mouse model of chronic UV-damage. Observe the expression of Caspase-3、Beclin-1、Bax and Bcl-2, which were regulatory elements between apoptosis and autophagy, within keratinocytes of mice skin exposed chronic ultraviolet radiation.Method Establish the model of chronic UV-damaged mice by exposing mice under the UV light (UVA+UVB).The radiation began form the MED (UVB0.07J/cm2, UVA0.7J/cm2), and increased0.5MED per week. The protocol contained1radiation per day,5radiation per week, total9weeks. The total dose of UVB9.45J/cm2and UVA94.5J/cm2.The expression of Caspase-3、Bax、Bcl-2、and Beclin-1pre/post treatment was detected via immunohistochemistry in epidermal keratinocytes of chronic UV-damaged mice.Pair t test,Wilcoxon signed ranks text and Spearman rank correlation analysis were performed for statistics.Result The average values of Bax、Bcl-2、Caspase-3and Beclin-1were0.30(0-2),0.25(0-2),0.35(0-2) and0.25(0-1) respectively in chronic UV-damaged group before UV radiation. The average values of Bax,Bcl-2,Caspase-3and Beclin-1were2.70(2-6),3.30(2-9),3.35(2-6) and0.25(0-1) respectively after UV radiation. The expression of Bax and Caspase-3in chronic UV-damaged group was higher than the control group.The difference between groups had statistical meaning (P<0.05),and increase of the two indicators have correlation (r=0.487,P<0.05).Significant difference was detect of the expression of Bax,Caspase-3and Beclin-1(P＜0.05) between the two groups.But no Significant difference in expression of Bcl-2(P>0.05). The average values of Bax,Bcl-2,Caspase-3and Beclin-1were0.20(0-1),0.20(0-1),0.30(0-1) and0.20(0-1) respectively in control group pre-treatment, and the average values of Bax、Bcl-2,Caspase-3and Beclin-1were 0.30(0-1),0.20(0-1),0.30(0-1) and0.10(0-1) respectively at the end of study. There was no statistical difference in expression of Bax,Bcl-2,Caspase-3and Beclin-1(P>0.05).Conclusion Repeated UV radiation can up-regulated the expression of Caspase-3and increase the apoptotic activity of epidermal keratinocytes in mice. And the increase of apoptotic activity is related with the up-regulated expression of Bax.Chronic UV radiation can up-regulate the expression of Beclin-1and Bax which both are involved in cross-talk of apoptosis and autophagy. It might play an important role in cross-talk of apoptosis and autophagy in chronic skin photodamage.