A Proteomics Study Of Human Epidermal Photoaging

Objective:The mechanism of epidermal photoaging process is not clear.This study is to analyze the differential proteins expressed in the normal elderly exposed epidermis and the non-exposed epidermis,exploring the role and molecular mechanism of keratinocytes in the skin photoaging process,which may reveal the nature of photoaging and lay a foundation for skin care.Methods: We collected the normal skin from the elderly exposed and non-exposed parts,and the specimens were stored in liquid nitrogen.After quickly rewarming in saline of 37℃,the epidermis was separated with dispase II from the dermis.Then the epidermal total proteins were extracted and were submitted to two-dimensional gel electrophoresis. Subsequently,their electrophoretic patterns were analyzed by the PDQUEST software.After intensity correction,background reduction, point detection, matching and ID correction,the selected proteins were analyzed by MALDT-TOF and then were inquired in database.At last, Western-blotting was used to detect the expression of different proteins.Results: The two-dimensional electrophoresis technique of human epidermis were established and optimized,and obtained high reproducibility electrophoresis patterns.The PDQUEST analysis showed that the exposed group spots were 536±17and the non-exposed group spots were 528±15. By comparison the two groups, 31 differential protein spots were determined,among which,15 protein spots were high expressed and 5 protein spots were only expressed in exposed group,8 protein spots were high expressed and 3 protein spots were only expressed in non-exposed group.We select 10 conspicuously distinct protein spots to analyse and 5 differential expressed proteins were successfully identified by mass spectrography and database querying.3 proteins , HSPB1,ANXA2,MK03, were identified to be high expressed in the exposed group,and K2C80 was only expressed in the exposed group, and GSTA2 was high expressed in the non-exposed group.The expression of HSPB1 and GSTA2 was testified different by Western-blotting.All of which showed the intimate correlation betwween the 5 proteins and skin photoaging.Conclusion: Differential expressed proteins were found in the normal elderly exposed epidermis and the non-exposed epidermis.The changes in expression of 5 identified proteins may have a close relationship with photoaging by maintaining the normal function of cells and suppressing inlammatory reaction and cell apoptosis, which may play an important role to reveal the molecular mechanism of epidermal cells in photoaging.