Characterization of epidermal growth factor in mouse testis.

Abstract

Considerable evidence exists to suggest that epidermal growth factor (EGF) influences spermatogenesis directly. The tissue source of this EGF, however, is not yet clear. In this study we examine whether the testis itself can serve as a source of EGF. Gel filtration fractions of acid extracted testes exhibited the ability to displace 125I-EGF from testis membranes. The testicular fractions containing the 125I-EGF displacement activity coeluted within the same range as those of submandibular gland (SG) fractions containing mature EGF and prepared in an identical fashion. Next, we employed specific antisera probes to investigate first, whether the testis synthesizes this EGF displacement activity and second, to determine the cell distribution of the testicular EGF. Two types of antisera probes were employed: 1) commercially available antisera to mature EGF (EGFm), i.e. the 6,000 M(r) peptide, and 2) polypeptide specific antisera to the C-terminus of the EGF precursor (EGFp), i.e. the 140,000 M(r) integral membrane molecule which exhibits seven EGF-like repeats in addition to the EGFm. Metabolic labeling of testis with 35S-methionine was performed, followed by immunoprecipitation with the anti-EGFm antisera. Parallel studies using kidney and SG were used as positive controls. Fluorograms exhibited a prominent band at M(r) 140,000 for testis and kidney, corresponding to the EGFp. There was, in addition, a M(r) 50,000 band present for the testis. In SG, a band at M(r) 6,000, corresponding to EGFm, in addition to bands at M(r) 21,000 and 46,000 were observed also. Immunoblotting of testis, kidney, and SG membrane preparations with the specific antisera to either the EGFm or EGFp also resulted in identifying the EGFp at M(r) 140,000, as well as other lower mol wt bands. Preadsorption of anti-EGFm antisera with excess EGFm eliminated all of the specific bands that were immunoblotted. Peroxidase immunocytochemistry of testis, kidney, and SG was also performed using the specific antisera to either EGFm or EGFp. EGFp and EGFm staining in SG and kidney was identical to previously published results in which the distribution of EGFm in these tissues was established. In testis, EGFm immunostaining showed positive results in Sertoli cells, pachytene spermatocytes and round spermatids. In contrast, EGFp immunostaining was limited to pachytene spermatocytes and round spermatids. These results suggest that the testis must now be included in the list of tissues capable of synthesizing EGFp. Specifically, EGFp synthesis appears limited to the post meiotic germ cells.

Identification of Early Response Genes and Pathway Activated by Androgens in the Initial Segment and Caput Regions of the Regressed Rat Epididymis

“…EGF precursor is also known to be produced in the testis (84). Testosterone interacts with EGF to influence the Wolffian duct formation during development (85). Androgen increases the Egf binding sites and modulates the cellular proliferation in the rat prostate (86).…”

Epidermal Growth Factor Regulates Glucose Metabolism Through Lactate Dehydrogenase A Messenger Ribonucleic Acid Expression in Cultured Porcine Sertoli Cells1

“…By using an immunohistochemistry approach, we have previously localized EGF and TGF␣ predominantly in the porcine testicular somatic cells, while EGF receptor (EGFR) was present in somatic and germ cells during postnatal development [18]. In the rat testis, immunoreactive EGF precursor (M r 140 000) and EGF (M r 6000) have been identified in germ cells, and in Sertoli cells and germ cells, respectively [19]. EGF has been reported to influence Sertoli cells, Leydig cells, and peritubular myoid cells by affecting several specific parameters (reviewed in [20,21]).…”

Correlation of appearance of metastasis-associated protein1 (Mta1) with spermatogenesis in developing mouse testis

“…Abnormalities in the expression, structure, or activity of EGF and its receptors contribute to 50% spermatogenesis disturbance (Wahab-Wahlgren et al 2003;Huleihel and Lunenfeld 2004). Furthermore, the testis itself can serve as a source of EGF, and EGFR is present exclusively in Sertoli cells (Radhakrishnan et al 1992). The mouse gene for histone deacetylase 1 has also been identified as being growthfactor-inducible (Bartl et al 1997).…”