Transcriptional and translational regulation of angiotensin II type 2 receptor by angiotensin II and growth factors.

The regulatory effects of angiotensin-II (AngII) and several growth factors, including insulin-like growth factor 1 (IGF-1), basic fibroblast growth factor (bFGF), and transforming growth factor beta1 (TGFbeta1) on the AngII subtype 2 (AT2) receptor were studied using R3T3 cells, a mouse fibroblast cell line that expresses only AT2 receptors. AngII increased (in a time- and dose-dependent manner) AT2 binding sites but had no effects on AT2 messenger RNA (mRNA) levels. At maximal concentration (10(-7) M) AngII caused a 4-fold increase of AT2 receptor number.

Food-dependent Cushing's syndrome: characterization and functional role of gastric inhibitory polypeptide receptor in the adrenals of three patients.

In the present work, the presence of gastric inhibitory polypeptide (GIP) receptors and their functional role in the adrenal cells of three patients with food-dependent Cushing's syndrome were studied. RT-PCR and in situ hybridization studies demonstrated the presence of GIP receptor in the adrenals of the three patients. The presence of this receptor was also demonstrated in two human fetal adrenals, but not in two normal adult human adrenals or in the adrenals of one patient with nonfood-dependent Cushing's syndrome.

Localization and quantitative expression of mRNAs encoding the testis-specific histone TH2B, the phosphoprotein p19, the transition proteins 1 and 2 during pubertal development and throughout the spermatogenic cycle of the rat.

Expression of the testis-specific histone TH2B, the phosphoprotein p19, and the transition proteins TP1 and TP2, was localized in the rat testis and quantified, using in situ hybridization of their mRNAs with radiolabeled probes and image analysis. In a first study, expression was assessed during testicular development between day 2 and day 65 postpartum. TH2B mRNAs appeared first in preleptotene spermatocytes (PL) on day 12 and in pachytene spermatocytes (PS) on day 18; p19 mRNAs were present in PS from day 18 onward, and TP1 and TP2 mRNAs were detected in round spermatids (RS) from day 32 onward.

Effects of growth factors on cell proliferation and angiotensin II type 2 receptor number and mRNA in PC12W and R3T3 cells.

Previous studies have suggested that the expression of angiotensin type 2 receptor was inversely related to cell proliferation. We examined the effects of insulin-like growth factor (IGF-1), basic fibroblast growth factor (bFGF), transforming growth factor beta1 (TGFbeta1) and fetal calf serum (FCS) on cell proliferation and AT2 binding sites and mRNA level in PC12W (rat pheochromocytoma cell line) and R3T3 (mouse fibroblast cell line) which express abundant AT2 receptors. In both cell lines, serum deprivation markedly increased both AT2 receptor number and mRNA.

Sertoli cell-germ cell interactions and TGF beta 1 expression and secretion in vitro.

Transforming growth factor beta 1 (TGF beta 1) has been reported to be secreted and to act within the somatic cells of the testis. We examined whether the TGF beta 1 expression is present at mRNA and protein levels in purified rat Sertoli cells (SC), purified pachytene spermatocytes (SPC), and early spermatids (SPT) cultured alone or together. SC expressed a single TGF beta 1 transcript of 2.

Pre- and postmeiotic expression of male germ cell-specific genes throughout 2-week cocultures of rat germinal and Sertoli cells.

The present study was aimed at examining, by reverse transcription polymerase chain reaction, the expression of germ cell-specific genes in cocultures of Sertoli cells with either pachytene spermatocytes (PS) or round spermatids (RS). In situ hybridization studies showed that the mRNAs encoding phosphoprotein p19 and the testis-specific histone TH2B were specifically expressed in PS whereas those encoding the transition proteins TP1 and TP2 were specific to RS. This resulted in p19:TP1 and TH2B:TP2 ratios that were much higher in PS fractions than in RS fractions prepared by elutriation.

Transcriptional regulation of the lutropin/human choriogonadotropin receptor and three enzymes of steroidogenesis by growth factors in cultured pig Leydig cells.

Recent data have shown that Leydig-cell-specific functions, and therefore steroidogenic capacity, can be regulated by lutropin/human choriogonadotropin collectively termed gonadotropin and by several growth factors that are produced by and act within the testis. However, the molecular mechanisms by which these factors regulate Leydig cells are not understood. In the present study, we have investigated the effects of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), insulin-like growth factor I (IGF-I) and transforming growth factor beta (TGF-beta) on mRNA for the gonadotropin receptor and three steroidogenic enzymes: cytochrome P-450scc, cytochrome P-450 17 alpha-hydroxylase/C17-20 lyase (17 alpha-hydroxylase), and 3 beta-hydroxysteroid dehydrogenase.

[Paracrine regulation of Leydig cells].

In addition to the endocrine control of Leydig cell functions by LH, paracrine control of Leydig cell functions has been suspected from the indirect stimulatory effect of FSH on Leydig cells. Coculture experiments of Leydig and Sertoli cells and the effect of Sertoli cell conditioned media on Leydig cells confirmed the production by Sertoli cells of acute steroideogenic factor(s) and factors involved in the positive or negative control of Leydig cell differenciated functions. Characterization and purification of these paracrine factors has been until recently unsuccessful.

Production of tgf-Beta and hgf receptor by a differentiated papillary thyroid-carcinoma cell-line (B-cpap) - implication in malignancy.

The B-CPAP cell line was obtained from a human differentiated papillary thyroid carcinoma. Previous studies showed that the cells present thyroid characteristics such as thyroglobulin production, phenotypic alterations such as synthesis of human chorionic gonadotropin hormone (HCG), expression of neuron specific enolase (NSE) and protein S100, and also somatic mutations of p53 and K-rns oncogenes. The present data further characterize this cell line and show an overexpression of transforming growth factor (TGF beta 1) and c-met gene product i.

Transcription and post-transcriptional regulation of luteotropin/chorionic gonadotropin receptor by the agonist in Leydig cells.

Porcine Leydig, cultured in a chemically defined medium, express luteotropin/human chorionic gonadotropin (LH/hCG) receptor and mRNA transcripts of several sizes (7.6, 6.7, 5.

[Functional interactions between somatic cells in the male gonad].

The existence of multiple interactions between somatic cells in the testis, has been suspected in vivo, and demonstrated in vitro by cocultures and cultures in the presence of conditioned media. Long term Sertoli-Leydig cell interactions results in a local regulation of the specific differentiated functions of these cells, and more precisely in a control of their responsiveness to their respective gonadotropin. Among the paracrine and/or autocrine factors, growth factors are involved in the control of differentiated functions.

Expression and regulation of transforming growth factor-beta 1 messenger ribonucleic acid and protein in cultured porcine Leydig and Sertoli cells.

In the present work, the expression and secretion of transforming growth factor-beta 1 (TGF beta 1) by immature pig Leydig and Sertoli cells were investigated. Both cell types express two TGF beta 1 mRNA transcripts of 2.5 and 3.

Immunohistochemical localization of transforming growth factor-beta 1 in the fetal and neonatal rat testis.

The localization of transforming growth factor-beta 1 in the fetal and neonatal rat testis (from day 13.5 of fetal life to postnatal day 20) was investigated by an immunohistochemical staining method employing a polyclonal anti-TGF-beta 1 antibody that does not cross react with either TGF-beta 2 or TGF-beta 3. In testis and mesonephros tissue, immunostaining for TGF-beta 1 was undetectable on fetal day 13.

Enhancement of testosterone secretion by normal adult human Leydig cells by co-culture with enriched preparations of normal adult human Sertoli cells.

An in-vitro method was developed to study Sertoli-Leydig cell interactions in man, using testes removed at the time kidneys were removed for transplantation from 6 young adult men (aged 17-45 years) after cerebral death. After collagenase digestion of testicular tissue, Leydig cells were purified on discontinuous Percoll gradients. Two fractions of Leydig cells, 'L2' and 'L3' which differed in their buoyant density (1.

Opposite vectorial secretion of insulin-like growth factor I and its binding proteins by pig Sertoli cells cultured in the bicameral chamber system.

A two-chamber system has been employed to investigate the vectorial secretion of insulin-like growth factor I (IGF-I) and its binding proteins (IGF-BPs) by pig Sertoli cells. The kinetics of transport of [3H]insulin as well as the transepithelial electrical resistance of filters coated with reconstituted basement membrane, in the absence of presence of Sertoli cells, indicated the formation of a functional barrier by Sertoli cells. The rates of diffusion of [125I]IGF-I or [125I]human CG were slower from the apical (AC) to the basal (BC) compartment than in the opposite direction.

Possible involvement of transforming growth factor-beta in the inhibition of rat pituitary tumor growth by estradiol.

We have shown that growth of F4Z2 cells and F4Z2 tumors was stimulated by estradiol, that of MtTF4 and F4P tumors was inhibited and that of F4P cells remained insensitive. In the present work we explore the possible role of transforming growth factor-beta (TGF-beta) as a mediator of estradiol action in these pituitary tumors and cell lines. In vivo, estradiol treatment increased the concentration of TGF-beta 1 mRNAs in tumors whose growth was inhibited by estradiol (MtTF4 and F4P) but not in tumors whose growth was stimulated (F4Z2).

Regulation of c-fos, c-jun, jun-B, and c-myc messenger ribonucleic acids by gonadotropin and growth factors in cultured pig Leydig cell.

The nuclear protooncogenes have been implicated in the coordinate regulation of gene expression during cell proliferation and differentiation. Previous work has shown that LH and human h CG as well as several growth factors including epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), transforming growth factor-beta, and insulin-like growth factor-I play a role in Leydig cell differentiated functions. To evaluate the possibility that protooncogenes mediate long term effects of these factors, their action on the levels of c-fos, c-jun, jun-B, and c-myc messenger (m) RNAs was studied.

Regulation by growth factors of Leydig cell differentiated functions.

In this paper the effects of growth factors on the differentiated function of pig Leydig cells and other steroidogenic cells are reviewed. Two types of action have been observed, i.e.

Cell-cell communication in the testis.

In addition to the well-established endocrine regulation of testicular functions by gonadotropins, many data accumulated in the last few years indicate that a local control is required for a normal production of androgens and spermatogenesis. In the present paper we review the cell-cell interactions between somatic and germ cells in the testis and their role on the function of each cell type. Also, we will present evidences indicating that some of these interactions are mediated by several growth factors produced and acting within the testis.

Control of production of insulin-like growth factor I by pig Leydig and Sertoli cells cultured alone or together. Cell-cell interactions.

The production of insulin-like growth factor I (IGF-I) by pig Leydig cells and pig Sertoli cells cultured alone or together was investigated. Human chorionic gonadotropin (hCG) and basic fibroblast growth factor (FGF) stimulate in a dose-dependent manner IGF-I production by Leydig cells. At maximal concentrations the effects of both factors were almost additive.

Regulation of pig Leydig cell aromatase activity by gonadotropins and Sertoli cells.

The present work was done to investigate the cell localization of testicular aromatase activity and its regulation in immature pig testis using an in vitro model. Leydig cells and Sertoli cells were isolated from immature pig testes and cultured alone or together in the absence or presence of human chorionic gonadotropin (hCG) or porcine follicle-stimulating hormone (pFSH) for 2 days. At the end of incubation, the amounts of testosterone (T), estrone sulfate (E1S) and estradiol (E2) were measured.