Characterization of eight novel proteins with male germ cell-specific expression in mouse.
BACKGROUND
Spermatogenesis and fertilization are highly unique processes. Discovery and characterization of germ cell-specific genes are important for the understanding of these reproductive processes. We investigated eight proteins encoded by novel spermatogenic cell-specific genes previously identified from the mouse round spermatid UniGene library.


METHODS
Polyclonal antibodies were generated against the novel proteins and western blot analysis was performed with various protein samples. Germ cell specificity was investigated using testes from germ cell-less mutant mice. Developmental expression pattern was examined in testicular germ cells, testicular sperm and mature sperm. Subcellular localization was assessed by cell surface biotin labeling and trypsinization. Protein localization and properties in sperm were investigated by separation of head and tail fractions, and extractabilities by a non-ionic detergent and urea.


RESULTS
The authenticity of the eight novel proteins and their specificity to spermatogenic cells were confirmed. In examining the developmental expression patterns, we found the presence of four proteins only in testicular germ cells, a single protein in testicular germ cells and testicular sperm, and three proteins in the testicular stages and mature sperm from the epididymis. Further analysis of the three proteins present in sperm disclosed that one is located at the surface of the acrosomal region and the other two are associated with cytoskeletal structures in the sperm flagellum. We name the genes for these sperm proteins Shsp1 (Sperm head surface protein 1), Sfap1 (Sperm flagellum associated protein 1) and Sfap2 (Sperm flagellum associated protein 2).


CONCLUSIONS
We analyzed eight novel germ cell-specific proteins, providing new and inclusive information about their developmental and cellular characteristics. Our findings will facilitate future investigation into the biological roles of these novel proteins in spermatogenesis and sperm functions.
Baek
Namhoe
N
Department of Life Science and Research Center for Biomolecular Nanotechnology, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea. NamHo.Baek@celltrion.com
Woo
Jong-Min
JM
Han
Cecil
C
Choi
Eunyoung
E
Park
Inju
I
Kim
Do Han
DH
Eddy
Edward M
EM
Cho
Chunghee
C
D000177:Acrosome / Q000502:physiology; D000818:Animals; D000906:Antibodies; D000918:Antibody Specificity; D015153:Blotting, Western; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015723:Gene Library; D008297:Male; D008540:Meiosis / Q000235:genetics; D051379:Mice; D008938:Mitosis / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D013082:Sperm Tail / Q000502:physiology; D013087:Spermatids / Q000166:cytology / Q000502:physiology*; D013090:Spermatocytes / Q000166:cytology / Q000502:physiology*; D013091:Spermatogenesis / Q000235:genetics*
D000906:Antibodies; D011506:Proteins