INITIAL FUNCTIONAL STUDY OF THE PRAME GENE FAMILY DURING SPERMATOGENESIS
Open Access
- Author:
- Lu, Chen
- Graduate Program:
- Animal Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- August 02, 2017
- Committee Members:
- Wansheng Liuf, Thesis Advisor/Co-Advisor
Francisco Javier Diaz, Committee Member
Troy Ott, Committee Member - Keywords:
- PRAME/PRAMEL1
immunoelectron microscopy
conditional knockout mice model
spermatogenesis - Abstract:
- Preferentially expressed antigen in melanoma (PRAME) is a cancer/testis (CT) antigen that is predominantly expressed in normal gametogenic tissues and a variety of tumors. Members of PRAME gene family encode leucine-rich repeat (LRR) proteins that provide a versatile structural framework for the formation of protein-protein interactions. The function of PRAME during testicular development and spermatogenesis remains unknown, although PRAME has been extensively studied in cancer biology and is believed to play a regulatory role in cancer cells. To explore the function of the PRAME gene in spermatogenesis, the subcellular localization of the PRAME and PRAMEL1 protein in mouse spermatogenic cells was characterized by immunoelectron microscopy. The results revealed that both PRAME and PRAMEL1 localized in various organelles in spermatogenic cells during spermatogenesis, including the nucleus, flagellum, intermitochondrial cement (IMC), and chromatoid body (CB). Apart from that, the PRAME protein was also detected in mitochondria while PRAMEL1 was observed in manchette. To further explore the function of the PRAME gene during spermatogenesis, we applied a conditional knockout (cKO) mouse model with PRAME gene mutated 3 days after birth. Compared with control mice, the cKO mice have smaller testes and less epididymis sperm at 4-month old (4M). When examining the first wave of spermatogenesis, a degradation of seminiferous tubules (with a dramatically reduce of germ cells) was detected in the testes of cKO mice at postnatal day (P) 21 and P35, although degradation of seminiferous tubules was hardly detected in P14 and P7 testes. Apoptosis was also increased in cKO mice at P7, P14 and P21. Ultrastructure analysis detected heterogeneous chromatin condensing with small and large vacuoles in the elongated spermatids of cKO mice, which was not observed in the control mice. Despite the observed disruptions in seminiferous tubules and spermatogenic cells, the cKO mice exhibited normal fertility as indicated by the pregnancy rate and litter size in mating tests. The results indicate that PRAME is involved in spermatogenesis, and the knockout of PRAME gene 3 days after birth in the mouse could lead to certain testis abnormality without a significant impact on male fertility.