The Expression and Cellular Localization of the Sperm Flagellar Protein MC31/CE9 in the Rat Testis. Possible Posttranscriptional Regulation during Rat Spermiogenesis.

Abstract

We isolated the MC31 cDNA clone coding the antigen specifically recognized by the monoclonal antibody mMC31, and found that MC31 was identical to rat CE9. Therefore, this molecule is called MC31/CE9. MC31/CE9, a member of the immunoglobulin superfamily molecules, was localized on the rat sperm flagellar plasma membrane. We analyzed the expression and cellular localization of MC31/CE9 mRNA and protein in the adult rat testis by use of Northern hybridization, in situ hybridization, and immunohistochemical analyses. In the course of spermatogenesis, MC31/CE9 mRNA first appeared in type B spermatogonia. The mRNA signal intensity increased progressively to pachytene spermatocytes and remained constantly at a considerable level throughout the subsequent phases of spermatocytes and round spermatids, and then decreased gradually from step-11 spermatids to disappear in step-15 spermatids. On the other hand, MC31/CE9 protein expression showed a bimodal pattern. Immunohistochemical analysis for the MC31/CE9 protein revealed its most intense immunoreactivity on the flagella of step-8 to step-19 elongated spermatids. The cytoplasmic immunoreactivity of the MC31/CE9 protein also appeared in preleptotene to early pachytene spermatocytes and elongated spermatids, with particularly intense immunoreactivity in the Golgi complexes of zygotene and early pachytene spermatocytes (stage XIII to III) as well as step-8 to step-13 spermatids. Between these two phases, the MC31/CE9 protein proved undetectable in the cytoplasm of any spermatogenic cells. Sertoli cells and Leydig cells were devoid of MC31/CE9 mRNA and its protein. Therefore, the production of MC31/CE9 is thought to be posttranscriptionally regulated during spermiogenesis.

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 3: Developmental changes in spermatid flagellum and cytoplasmic droplet and interaction of sperm with the zona pellucida and egg plasma membrane

“…At steps 11-13, it appears on the whole tail and then redistributes to the posterior tail between steps 13 and 14 and during spermiation. CE9 redistributes along the tail coincident with the caudal migration of the annulus late in spermiogenesis (Cesario et al, 1995;Toshimori et al, 2001;Wakayama et al, 2000).…”

Sperm Plasma Membrane Modifications Associated with Fertilization in Mammals

“…We recently found that MC31 is homologous to CE9, based on cDNA analysis [49]. However, the results are somewhat different from that of CE9, probably due to differences in the epitope or antibody raised.…”

“…An in situ hybridization study of the MC31/CE9 mRNA expression showed that the mRNA is first found in leptotene spermatocytes throughout their development to elongated spermatids [49]. The protein is initially expressed in leptotene spermatocytes to testicular sperm [33], which is basically the same as that of CE9 [54].…”

“…CE9 and MC31/CE9: Typical modification of flagellar plasma membrane proteins is found in CE9 [32,48] and MC31 [33,49]. We recently found that MC31 is homologous to CE9, based on cDNA analysis [49].…”

Biology of spermatozoa maturation: An overview with an introduction to this issue

“…These processes induce the reorganization of membrane proteins, with the relocation or reorganization within or across the domain(s), as evidenced by immunostaining pattern changes. Such cases are typically found in the ADAM or MDC protein (ADAM family, Primakoff and Myles, 2000;Blobel, 2000;MDC family, Frayne et al, 1998) and in some membrane proteins belonging to the immunoglobulin superfamily (CE9, Petruszak et al, 1991;Cesario and Bartles, 1994; MC31(CE9), Toshimori et al, 1992;Wakayama et al, 2000;basigin, Saxena et al, 2002).…”