Chronological gene expression of ADAMs during testicular development: Prespermatogonia (gonocytes) express fertilin β (ADAM2)

Abstract

Immediately after birth, primordial germinal cell-derived prespermatogonia (PSG), located in the center of the testicular cords, migrate between adjacent Sertoli cells to establish contact with the cord basal lamina. PSG migration suggests continued assembly and disassembly of cell-cell contacts by a molecular mechanism that may involve integrins and their ligands, the disintegrin domain of spermatogenic cell-specific plasma membrane proteins called ADAMs. We have analyzed the temporal gene expression of selected ADAMs in intact fetal, early postnatal, and pubertal rat testis and Sertoli-spermatogenic cell cocultures by reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunocytochemistry. We report that several ADAM transcripts are expressed in fetal, neonatal, and prepubertal testes. Cyritestin (ADAM3), ADAM5, ADAM6, and ADAM15 are expressed in day 17 fetal testes. In contrast, no expression of fertilin ␣ (ADAM1) and fertilin ␤ (ADAM 2) was detected in fetal testes. Fertilin ␤ gene expression starts after postnatal day 2, subsequent to the expression of fertilin ␣, which occurs on postnatal day 1. After postnatal day 2, all the indicated ADAMs, including the fertilin ␣ and fertilin ␤, continue to be expressed. Transcripts of spermatogenic cell-specific fertilin ␣, fertilin ␤, ADAM3, and ADAM5 were detected during the coculture of PSG with Sertoli cells for up to 72 hr after plating. The presence of fertilin ␤ mRNA and protein in cocultured PSG was visualized by in situ hybridization and immunocytochemistry, respectively. These observations indicate that PSG in coculture with Sertoli cells provide a suitable approach for analyzing cell-cell adhesive responses involving spermatogenic cell-specific ADAMs.

RFX2 is a candidate downstream amplifier of A-MYB regulation in mouse spermatogenesis

“…ADAM5 is part of a large family of transmembrane proteins that can serve as integrin ligands. While it is detected in the embryonic prospermatogonia [55], it is also expressed during spermatogenesis and appears on the mature sperm surface after undergoing proteolytic processing in the epididymis [56]. These three genes have X box motifs with strong binding affinities and each shows marked up-regulation in developing testes at a point coincident with early entry into pachytene [30].…”

Gonocytes, the forgotten cells of the germ cell lineage

“…ADAM 1 and ADAM 2 were originally found at the surface of sperm and believed to play a role in sperm‐egg interaction (Chen and Sampson,1999), although the generation of ADAM2 and β1 KO mice subsequently showed that these proteins were not required for gamete fusion (Cho et al,2000; He et al,2003). ADAM 1 and ADAM 2 are not expressed in PGCs and appear at dpp1 (ADAM1) and dpp2 (ADAM2) mouse gonocytes (Rosselot,2003). Integrins α3β1 and α6β1 bind laminin, a major component of the seminiferous tubule basement membrane, and they play a critical role in Sertoli‐germ cell interactions as well as germ cell survival (Siu and Cheng,2004a,b).…”

Genomic origin, processing and developmental expression of testicular outer dense fiber 2 (ODF2) transcripts and a novel nucleolar localization of ODF2 protein

“…Sections were stained for 5 min with 5% uranyl acetate in deionized water and examined using a JEM-100CX transmission electron microscope operated at an accelerating voltage of 60 kV. Sections (1 mm-thick) of Lowicryl-embedded tissue were immunoreacted with ODF2-specific antibody, bound antibody visualized with anti-rabbit IgG-fluorescein isothiocyanate (working dilution: 1:200), stained with propidium iodide using a reported protocol (Rosselot et al, 2003) and observed by episcopic fluorescence microscopy.…”