Abnormal Expression of COX5B Gene and Disorder of Mitochondrial Function in Cryptorchid Rats

Cryptorchidism is one of the most common congenital malformations in the paediatric genitourinary tract. Data analysis of cryptorchidism-related datasets in the GEO database and gene sequencing results from our institution, along with bioinformatic analysis of the merged mitochondrial gene datasets, revealed that COX5B is differentially expressed in the testes of children with cryptorchidism. Its encoded protein has attracted our attention as a key component of the mitochondrial respiratory chain complex IV. This study aims to explore the COX5B gene expression changes and related mitochondrial issues in cryptorchid rats. For this purpose, we established a cryptorchid rat model by surgery and used molecular biology and biochemistry techniques to detect and analyse the expression level of the COX5B gene and mitochondrial function indexes. The results indicated a significant decrease in COX5B gene expression in the affected testis of cryptorchid rats. The knockdown of COX5B expression in TM3 cells could be observed as the aggravation of cellular senescence, which led to the reduction of proliferation, as well as accompanied by the obvious disorders of mitochondrial function, including the increase of ROS and the decrease of ATP, in which MMP was significantly reduced. This suggests that the COX5B gene may play an important role in cryptorchid testis-induced reproductive system damage and may be a new target for small molecule-targeted therapy.