Tetraspanin family protein CD9 in the mouse sperm: unique localization, appearance, behavior and fate during fertilization

• Published in: Cell and tissue research Vol. 340; no. 3; pp. 583 - 594
• Main Authors: Ito, Chizuru, Yamatoya, Kenji, Yoshida, Keiichi, Maekawa, Mamiko, Miyado, Kenji, Toshimori, Kiyotaka
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01-06-2010; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Acrosome Reaction - physiology; Animals; Antigens, CD - genetics; Antigens, CD - metabolism; Antigens, CD - ultrastructure; Biomedical and Life Sciences; Biomedicine; C57BL/6; Cellular biology; Female; fertilization (reproduction); Fertilization - physiology; Gamete biology; Gene expression; Gene Expression Regulation; Human Genetics; Male; Males; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membrane Glycoproteins - ultrastructure; Mice; Mice, Inbred C57BL; Molecular Medicine; Molecular Weight; Mouse (ICR; Protein Transport; Proteins; Proteomics; Regular Article; Reproductive system; RNA; Rodents; Sperm Maturation - physiology; spermatogenesis; Spermatozoa; Spermatozoa - cytology; Spermatozoa - metabolism; Spermatozoa - ultrastructure; testes; Tetraspanin-29; Testis; Gamete biology; Mouse (ICR; C57BL/6); Fertilization; Sperm; Spermatogenesis
• ISSN: 0302-766X; 1432-0878
• DOI: 10.1007/s00441-010-0967-7

A tetraspanin family protein, CD9, has not previously been identified in sperm cells. Here, we characterize sperm CD9 in the mouse, including its unique localization in sperm, appearance during spermatogenesis, and behavior and fate during mouse fertilization. In sperm, CD9 is an inner acrosomal membrane-associated protein, not a plasma membrane-associated protein. Its molecular weight is approximately 24 kDa throughout its processing, from testicular germ cells to acrosome-reacted sperm. A temporal difference was found between mRNA and protein expression; CD9 mRNA was detected in the stages from spermatogonia through round spermatids showing the strongest levels in midpachytene spermatocytes. CD9 protein was detected in the cytoplasm throughout the stages from spermatogonia to spermatocytes. While CD9 was weakly expressed in the spermatids from step 1 through step 14, the signals became clearly positive at the marginal region of the anterior acrosome in elongated spermatids. After the acrosome reaction, the majority of sperm CD9 was retained in the inner acrosomal membrane, but some quantity of CD9 was found on the plasma membrane covering the equatorial segment as detected by immunogold electron microscopy using anti-CD9 antibody. CD9 was maintained on the sperm head after reaching the perivitelline space of CD9-deficient eggs that were recovered after natural mating with wild males. Thus, this study characterizes CD9 in sperm development and fertilization.