A study of p53-binding protein 1 in sperm function

Abstract

Spermatozoa experience a series of physiological alternation upon traveling from the testis to the epididymis in order to acquire motility and capacity necessary to recognize and to fuse with an oocyte. Further maturation and modification of the spermatozoa occur along the journey in the female reproductive tract in a process known as capacitation. p53 protein is a well-known transcription factor involved in guarding of genome integrity by triggering cell cycle arrest and cell death upon DNA damage. p53-binding protein 1 (53BP-1) binds to p53 and enhances p53-mediated transcriptional activity. It has been reported that human spermatozoa produce 53BP-1 for DNA repair in response to oxidative stress. 53BP-1 is expressed in pre-implantation embryos. The current study aimed to identify the expression and subcellular location of 53BP-1 proteins in mouse spermatozoa by immunofluorescence staining. Increased expression of 53BP-1 proteins was found in the swim-up and capacitated mouse spermatozoa. The immunoreactivity was localized to the sperm head and midpiece, suggesting possible roles of 53BP-1 in sperm function. It was also found that mouse oocytes and 1-cell embryo also expressed 53BP-1. The potential function of 53BP-1 in early embryo development was also investigated using 53BP-1 antibody neutralized sperm in in-vitro fertilization. There was no significant difference between the development rate of embryos fertilized with spermatozoa transduced with anti-53BP-1 antibody and those that transduced with the control goat IgG. Further studies are needed to investigate the role of sperm 53BP-1 at later stage of embryo development and implantation.