TGF-.BETA.1 System in Leydig Cells. Part I: Effect of hCG and Progesterone

Abstract

Abstract. Transforming growth factor beta 1 (TGF-β1) modulates male reproductive function. Genetically modified mice overexpressing α/β subunits of hCG (hCG+) show Leydig cell hyperplasia/hypertrophy at prepuberty that disappears as the mice approach adulthood. In this study we analyzed the gene expression of TGF-β1, its specific receptors, type II (TGF-βRII) and type I (activin receptor-like kinase 1 and 5: ALK1 and ALK5), and co-receptor endoglin (CD105) in purified Leydig cells from hCG+ and wild-type mice at 3 and 8 weeks of age and the occurrence of TGF-β1, ALK1 and ALK5 by immunohistochemistry. The expression of TGF-β1 was higher in hCG+ mice at both ages studied, and no changes were observed in TGF-βRII. ALK5 diminished with age in wild-type mice, whereas ALK1 decreased in hCG+ mice at 8 weeks of age. Endoglin expression showed a marked increase in 3-week-old hCG+ animals. In vitro incubation of Leydig cells from wild-type animals with hCG (10 IU/ml) increased TGF-β1 and ALK5 expression. Progesterone (10 -6 M) induced endoglin expression. These studies provide novel evidence for differential gene and protein expression of ALK1 and ALK5 at different ages and endoglin expression and hormonal, in purified Leydig cells. Key words: ALK, Endoglin (CD105), Leydig, Testis, TGF-beta 1 (J. Reprod. Dev. 56: [389][390][391][392][393][394][395] 2010) esticular function is under the control of a complex network of hormones, growth factors and cytokines [1], including the transforming growth factor β (TGF-β) family that involves three related peptides: TGF-β1, TGF-β2 and TGF-β3. They share homology with other members of the family, such as inhibins, activins, anti-Mullerian hormone (AMH) and bone morphogenetic proteins (BMPs) [2,3]. These molecules have a critical role in regulating cell cycle progression and differentiation in a broad range of tissues under normal and pathological conditions [2,4,5]. In the testis, TGF-β regulates a variety of cellular processes, comprising the secretory functions of Leydig and Sertoli cells, the organization of peritubular myoid cells, testis development and spermatogenesis [5][6][7].Several mechanisms are known to regulate the expression of TGF-β ligands and receptors [3], but their functions in the testis are not well established. Testosterone and FSH suppress the expression of TGF-β1 in cultured porcine Leydig and Sertoli cells, respectively [8], and hCG stimulates TGF-βRI and TGF-βRII expression in cultured porcine Leydig cells, whereas steroid hormones have no effect [9]. New genetically modified animal models have proven important in increasing our understanding of testicular pathologies associated with gonadotropin function.Transgenic male mice overexpressing α and β subunits of hCG (hCG+ mice) are infertile, and their reproductive organs show severe alterations, such as smaller testes, enlarged seminal vesicles and prostate and dilated vasa deferentia and urinary bladder [10].In addition, testicular steroidogenesis is enhanced despite a clear down-regulation of LH/hCG recep...

TGF-.BETA.1 System in Leydig Cells. Part II: TGF-.BETA.1 and Progesterone, Through Smad1/5, are Involved in the Hyperplasia/hypertrophy of Leydig Cells

“…Progesterone alone did not modify PCNA immunodetection; however, it has been observed that progesterone stimulates endoglin gene expression in mouse Leydig cells [17]. Moreover, incubation of Leydig cells with TGF-β1 and progesterone diminished the expression of Bax (pro-apoptotic gene) without any modification of Bcl-2 (anti apoptotic gene) expression, causing a lower Bax/Bcl-2 ratio compared with the control treatments.…”

Expression of the TGF-beta1 system in human testicular pathologies

“…Recently, we have described the hormonal regulation of TGF-β1 system in an experimental model [41] and that the in vitro effect of TGF-β1 on mouse Leydig cell induces Smad 1/5 phosphorylation and proliferation markers (Bax/Bcl-2 ratio, PCNA) [41]. …”

Functional role of progestin and the progesterone receptor in the suppression of spermatogenesis in rodents

“…Another study reported that PR was expressed in a few peritubular and interstitial cells, but not in germ cells of human and nonhuman primates (Luetjens et al, 2006). PR has been shown to be present in rodent Leydig cells (Pino & Valladares, 1988;El-Hefnawy et al, 2000;Gonzalez et al, 2010). In this study, we examined the PR localization in mouse testes by detecting PR promoter driven b-gal expression, and demonstrated that intratesticular hormonal deprivation resulted in PR promoter driven LacZ expression predominantly in Leydig cells.…”