The aged testis. A good model to find proteins involved in age-related changes of testis by proteomic analysis.

To explore associated proteins involved in age-related changes of the testis and better understand the roles of these proteins in the human testis. We used two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spec trometry analysis to identify differentially expressed proteins between the aged and the normal control groups. The L-lactate dehydrogenase C chain (LDHC) protein, a previous testis-specific protein, was found to be downregulated in the aged testis and was further tested with western blot and immunohistochemical analysis to verify the result of the LDHC protein in 2-DE. Twelve differentially expressed proteins were identified. Among those proteins, 3 were upregulated and 9 were downregulated in the aged group. The results of western blot and immunohistochemical analysis confirmed the expression of LDHC downregulation in the aged testis. Some proteins identified had little well-known function in the human testis, as follows: AKR7A3, FDXR, PGAM1, SEPT2 and HMGCS2. Our results imply that the aged testis can be a good model to find associated proteins involved in age-related changes of the testis. It can be useful to understand the roles of those proteins in the testis.