Expression of platelet-derived growth factor (PDGF) in the epididymis and analysis of the epididymal development in PDGF-A, PDGF-B, and PDGF receptor beta deficient mice

Lymphatic muscle cells are the innate pacemaker cells regulating mouse lymphatic collecting vessel contractions

Collecting lymphatic vessels (cLVs) exhibit spontaneous contractions with a pressure-dependent frequency, but the identity of the lymphatic pacemaker cell is still debated. By analogy to pacemakers in the GI and lower urinary tracts, proposed cLV pacemaker cells include interstitial cells of Cajal like cells (ICLC), pericytes, as well as the lymphatic muscle (LMCs) cells themselves. Here we tested the extent to which these cell types are invested into the mouse cLV wall and if any cell type exhibited morphological and functional processes characteristic of pacemaker cells: a contiguous network; spontaneous Ca2+ transients; and depolarization-induced propagated contractions. We employed inducible Cre (iCre) mouse models routinely used to target these specific cell populations including: c-kitCreERT2 to target ICLC; PdgfrβCreERT2 to target pericytes; PdgfrαCreER™ to target CD34+ adventitial fibroblast-like cells or ICLC; and Myh11CreERT2 to target LMCs. These specific inducible Cre lines were crossed to the fluorescent reporter ROSA26mT/mG, the genetically encoded Ca2+ sensor GCaMP6f, and the light-activated cation channel rhodopsin2 (ChR2). c-KitCreERT2 labeled both a sparse population of LECs and round adventitial cells that responded to the mast cell activator compound 48-80. PdgfrβCreERT2 drove recombination in both adventitial cells and LMCs, limiting its power to discriminate a pericyte specific population. PdgfrαCreER™ labeled a large population of interconnected, oak leaf-shaped cells primarily along the adventitial surface of the vessel. Titrated induction of the smooth muscle-specific Myh11CreERT2 revealed a LMC population with heterogeneous morphology. Only LMCs consistently, but heterogeneously, displayed spontaneous Ca2+ events during the diastolic period of the contraction cycle, and whose frequency was modulated in a pressure-dependent manner. Optogenetic depolarization through the expression of ChR2 by Myh11CreERT2, but not PdgfrαCreER™ or c-KitCreERT2, resulted in a propagated contraction. These findings support the conclusion that LMCs, or a subset of LMCs, are responsible for mouse cLV pacemaking.

High-throughput proteomic characterization of seminal plasma from bulls with contrasting semen quality

Seminal plasma proteins are the major extrinsic factors that can modulate the sperm quality and functions. The present study was carried out to compare the proteomic profiles of seminal plasma from breeding bulls producing good and poor quality semen in an effort to understand the possible proteins associated with semen quality. A total of 910 and 715 proteins were detected in the seminal plasma of poor and good quality semen producing bulls, respectively. A total of 705 proteins were common to both the groups, in which 380 proteins were upregulated and 89 proteins were downregulated in the seminal plasma of poor quality semen, while 236 proteins were co-expressed. The proteins negatively influencing sperm functions such as CCL2, UQCRC2, and SAA1 were among the top ten upregulated proteins in the seminal plasma of poor quality semen. Proteins having a positive role in sperm functions (NGF, EEF1A2, COL1A2, IZUMO4, PRSS1, COL1A1, WFDC2) were among the top ten downregulated proteins in the seminal plasma of poor quality semen. The upregulation of oxidation-reduction process-related proteins, histone proteins (HIST3H2A, H2AFJ, H2AFZ, H2AFX, HIST2H2AB, H2AFV, HIST1H2AC, HIST2H2AC, LOC104975684, LOC524236, LOC614970, LOC529277), and ubiquinol-cytochrome-c reductase proteins (UQCRB, UQCRFS1, UQCRQ, UQCRC1, UQCRC2) indicate deranged oxidation-reduction equilibrium, chromatin condensation and spermatogenesis in poor quality semen producing bulls. The expression of proteins essential for motile cilium (CCDC114, CFAP206, TEKT4), chromatin integrity (PRM2), gamete fusion (IZUMO4, EQTN), hyperactivation, tyrosine phosphorylation, and capacitation [PI3K-Akt signalling pathway-related proteins (COL1A1, COL2A1, COL1A2, SPP1, PDGFA, NGF)] were down regulated in poor quality semen producing bulls.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03474-6.

B16 melanomas evade antitumor immunity by the loss of epitope presentation and the acquisition of tumor resistance to granzyme B

Melanomas exhibit the highest rate of heterogeneity among cancer cell types. In this study, we tested the two types of B16 melanoma cells (B16-S0-1 and B16-S1-1) showing resistance to antitumor immunity. These cells expressed Trp2 protein. Contrary to B16 and B16-S0-1 cells, B16-S1-1 cells failed to stimulate IFN-γ responses in Trp2-specific CD8+ T cells, suggesting that B16-S1-1 cells may have lost the ability to present antigen to Ag-specific CTLs in the context of MHC class I molecules. However, B16-S0-1 cells exhibited active Stat3 and decreased Bcl-2 expression, which were found to be not associated with immune escape. B16-S0-1 cells were more resistant to granzyme B-mediated caspase activation and apoptosis than B16 cells. Thus, these data show that B16 cells escape antitumor immune responses through the loss of epitope presentation to CTLs and the acquisition of tumor cell resistance to granzyme B-mediated caspase activation.

The effect of imatinib administered in the prenatal period on testis development in rats

BACKGROUND

The purpose of this study was to examine the effects of exposure to imatinib in the prenatal period on testis development in rats.

METHODS

Although all the study groups received intraperitoneal imatinib on prenatal days 1-8, no pregnancy occurred in the Imatinib-80 group. Immunohistochemical analysis, TUNEL, c-kit and PDGF staining revealed no difference between the groups in terms of positivity scoring.

RESULTS

A significant decrease was detected in total sperm counts in the Imatinib-20 group compared to the control group, but the sperm count was higher in the Imatinib-60 group than in the Imatinib-20 group. At biochemical measurements, the drug increased oxidative stress in the testis and serum in the Imatinib-20 group, but caused a decrease in tissue in the Imatinib-60 group. Thiol measurements revealed a decrease in the testis and serum in the Imatinib-60 group, while an increase in serum measurements was observed in the Imatinib-40 group. Analysis revealed no difference between the groups in terms of protamine and histone gene expression levels in testis tissue exposed to imatinib.

CONCLUSION

Our findings show that prenatal exposure to imatinib can lead to histopathological and biochemical changes in testis tissue, but that no adverse effect occurs in nuclear maturation of germ cells during spermiogenesis.

Hepatocyte-specific expression of constitutively active Alk5 exacerbates thioacetamide-induced liver injury in mice

While Transforming growth factor-βs (Tgf-βs) have been known to play an important role in liver fibrosis through an activation of Hepatic Stellate Cells (HSC), their fibrotic role on hepatocytes in liver damage has not been addressed thoroughly. To shed more light on the hepatocyte-specific role of Tgf-β signaling during liver fibrosis, we generated transgenic mice expressing constitutively active Tgf-β type I receptor Alk5 under the control of albumin promoter. Uninjured mice with increased Tgf-β/Alk5 signaling in hepatocytes (caAlk5/Alb-Cre mice) did not show characteristics related to hepatocyte death, fibrosis and inflammation. When subjected to thioacetamide (TAA) treatment, caAlk5/Alb-Cre mice exhibited more severe liver injury, when compared to control littermates. After TAA administration for 12 weeks, an increase in pathological changes was evident in caAlk5/Alb-Cre livers, with higher number of infiltrating cells in the portal and periportal area. Immunohistochemistry for F4/80, myeloperoxidase and CD3 showed that there was an increased accumulation of macrophages, neutrophils and T-lymphocytes, respectively, in caAlk5/Alb-Cre livers. Coincidently, we observed an exacerbated liver damage as seen by increases in serum aminotransferase level and number of apoptotic hepatocytes in caAlk5/Alb-Cre mice. Sirius staining of collagen demonstrated that the fibrotic response was worsened in caAlk5/Alb-Cre mice. The enhanced fibrosis in mutant livers was associated with marked production of α-SMA-positive myofibroblast. Hepatic expression of genes indicative of HSC activation was greater in caAlk5/Alb-Cre mice. In conclusion, our data indicated that elevation of Tgf-β signaling via Alk5 in hepatocytes is not sufficient to induce liver pathology but plays an important role in amplifying TAA-induced liver damage.

Open chromatin mapping identifies transcriptional networks regulating human epididymis epithelial function

The epithelium lining the epididymis in the male reproductive tract maintains a luminal environment that promotes sperm cell maturation. This process is dependent on the coordinated expression of many genes that encode proteins with a role in epithelial transport. We previously generated genome-wide maps of open chromatin in primary human epididymis epithelial (HEE) cells to identify potential regulatory elements controlling coordinated gene expression in the epididymis epithelium. Subsequent in silico analysis identified transcription factor-binding sites (TFBS) that were over-represented in the HEE open chromatin, including the motif for paired box 2 (PAX2). PAX2 is a critical transcriptional regulator of urogenital tract development, which has been well studied in the kidney but is unexplored in the epididymis. Due to the limited lifespan of primary HEE cells in culture, we investigated the role of PAX2 in an immortalized HEE cell line (REP). First, REP cells were evaluated by DNase I digestion followed by high-throughput sequencing and the PAX2-binding motif was again identified as an over-represented TFBS within intergenic open chromatin, though on fewer chromosomes than in the primary HEE cells. To identify PAX2-target genes in REP cells, RNA-seq analysis was performed after siRNA-mediated depletion of PAX2 and compared with that with a non-targeting siRNA. In response to PAX2-repression, 3135 transcripts were differentially expressed (1333 up-regulated and 1802 down-regulated). Novel PAX2 targets included multiple genes encoding proteins with predicted functions in the epididymis epithelium.

Cooperative effects of 17β-estradiol and oocyte-derived paracrine factors on the transcriptome of mouse cumulus cells

Oocyte-derived paracrine factors (ODPFs) and estrogens are both essential for the development and function of ovarian follicles in mammals. Cooperation of these two factors was assessed in vitro using intact cumulus-oocyte complexes, cumulus cells cultured after the removal of oocytes [oocytectomized (OOX) cumulus cells], and OOX cumulus cells cocultured with denuded oocytes, all in the presence or absence of 17β-estradiol (E2). Effects on the cumulus cell transcriptome were assessed by microarray analysis. There was no significant difference between the cumulus cell transcriptomes of either OOX cumulus cells cocultured with oocytes or intact cumulus-oocyte complexes. Therefore, oocyte-mediated regulation of the cumulus cell transcriptome is mediated primarily by ODPFs and not by gap junctional communication between oocytes and cumulus cells. Gene ontology analysis revealed that both ODPFs and E2 strongly affected the biological processes associated with cell proliferation in cumulus cells. E2 had limited effects on ODPF-regulated biological processes. However, in sharp contrast, ODPFs significantly affected biological processes regulated by E2 in cumulus cells. For example, only in the presence of ODPFs did E2 significantly promote the biological processes related to phosphorylation-mediated signal transduction in cumulus cells, such as the signaling pathways of epidermal growth factor, vascular endothelial growth factor, and platelet-derived growth factor. Therefore, ODPFs and E2 cooperate to regulate the cumulus cell transcriptome and, in general, oocytes modulate the effects of estrogens on cumulus cell function.

Implication of PDGF signaling in cigarette smoke-induced pulmonary arterial hypertension in rat

Pulmonary artery hypertension (PAH) is a severe disease characterized with progressive increase of pulmonary vascular resistance that finally causes right ventricular failure and premature death. Cigarette smoke (CS) is a major factor of Chronic Obstructive Pulmonary Disease (COPD) that can lead to PAH. However, the mechanism of CS-induced PAH is poorly understood. Mounting evidence supports that pulmonary vascular remodeling play an important role in the development of PAH. PDGF signaling has been demonstrated to be a major mediator of vascular remodeling implicated in PAH. However, the association of PDGF signaling with CS-induced PAH has not been documented. In this study, we investigated CS-induced PAH in rats and the expression of platelet derived growth factor (PDGF) and PDGF receptor (PDGFR) in pulmonary artery. Forty male rats were randomly divided into control group and three experimental groups that were exposed to CS for 1, 2, and 3 months, respectively. CS significantly increased right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI). Histology staining demonstrated that CS significantly increased the thickness of pulmonary artery wall and collagen deposition. The expression of PDGF isoform B (PDGF-B) and PDGF receptor beta (PDGFRβ) were significantly increased at both protein and mRNA levels in pulmonary artery of rats with CS exposure. Furthermore, Cigarette smoke extract (CSE) significantly increased rat pulmonary artery smooth muscle cell (PASMC) proliferation, which was inhibited by PDGFR inhibitor Imatinib. Thus, our data suggest PDGF signaling is implicated in CS-induced PAH.

Why are epididymal tumours so rare?

Epididymal tumour incidence is at most 0.03% of all male cancers. It is an enigma why the human epididymis does not often succumb to cancer, when it expresses markers of stem and cancer cells, and constitutively expresses oncogenes, pro-proliferative and pro-angiogenic factors that allow tumour cells to escape immunosurveillance in cancer-prone tissues. The privileged position of the human epididymis in evading tumourigenicity is reflected in transgenic mouse models in which induction of tumours in other organs is not accompanied by epididymal neoplasia. The epididymis appears to: (i) prevent tumour initiation (it probably lacks stem cells and has strong anti-oxidative mechanisms, active tumour suppressors and inactive oncogene products); (ii) foster tumour monitoring and destruction (by strong immuno-surveillance and -eradication, and cellular senescence); (iii) avert proliferation and angiogenesis (with persistent tight junctions, the presence of anti-angiogenic factors and misplaced pro-angiogenic factors), which together (iv) promote dormancy and restrict dividing cells to hyperplasia. Epididymal cells may be rendered non-responsive to oncogenic stimuli by the constitutive expression of factors generally inducible in tumours, and resistant to the normal epididymal environment, which mimics that of a tumour niche promoting tumour growth. The threshold for tumour initiation may thus be higher in the epididymis than in other organs. Several anti-tumour mechanisms are those that maintain spermatozoa quiescent and immunologically silent, so the low incidence of cancer in the epididymis may be a consequence of its role in sperm maturation and storage. Understanding these mechanisms may throw light on cancer prevention and therapy in general.

Seasonal changes in morphology and immunoreactivity of PDGF-A and its receptor PDGFR-α in the epididymis of wild ground squirrels (Citellus dauricus Brandt)

The platelet-derived growth factor (PDGF) system is expressed and can exert its biological role in the male reproductive system including the maintenance of morphological structure and function of the epididymis. The aim of this study was to clarify the relationship between the PDGF system and seasonal changes in morphology of the wild ground squirrel epididymis during the breeding and nonbreeding seasons. Hematoxylin-eosin (HE) staining was used to observe the epididymal morphology and histology. Immunohistochemistry and Western blotting were performed to detect the immunoreactivities of PDGF-A and B and PDGFR-α. Significant seasonal changes in epididymal morphology were observed in the breeding and nonbreeding seasons. The proportions of the three compartments (interstitial tissue, epithelium and lumen of the duct) revealed distinct variances. Strong immunostaining of PDGF-A was present in the myoid cell and on the sperm in the breeding season, whereas there was a faint signal in the myoid cell in the nonbreeding season. PDGFR-α was expressed in all cell types of the epithelium throughout the whole seasonal cycle, and immunostaining of PDGFR-α in the breeding season was significantly stronger compared with that of the nonbreeding season. PDGF-B was not detected in the epididymis of wild ground squirrels. These results suggested that seasonal morphological changes in epididymis were correlated with immunoreactivities of PDGF-A and its receptor PDGFR-α and that PDGF-A and PDGFR-α might function as paracrine, autocrine or apocrine factors in wild ground squirrels.

Platelet-derived growth factor receptor beta-subtype regulates proliferation and migration of gonocytes

Proliferation and migration of gonocytes, the precursors of spermatogonial stem cells, to the germline niche in the basal membrane of the seminiferous tubules, are two crucial events that take place between postnatal d 0.5 (P0.5) and P5.0 in the mouse and involve a selection of the cells that are committed to the germline stem cells lineage. Here we show that from embryonic d 18.0 (E18) and up to P5, the gonocytes express platelet-derived growth factor (PDGF) receptor beta-subtype (PDGFR-beta) and that during the same time period, the Sertoli cells express PDGF-B and PDGF-D, both ligands for PDGFR-beta. Inhibition of the PDGFR-beta tyrosine kinase activity during the first five postnatal days provokes a profound reduction of gonocyte number through inhibition of their proliferation and induction of apoptosis. Moreover, we found that PDGFR-beta ligands are chemotactic for gonocytes. These data suggest that PDGFR-beta activation has the remarkable capability to drive the selection, survival, and migration of the gonocytes from the center of the seminiferous tubules to the testicular germline niche on the basal membrane.

Involvement of platelet-derived growth factor receptor-beta in maintenance of mesenchyme and sensory epithelium of the neonatal mouse inner ear

Platelet-derived growth factor receptor (PDGFR) signaling has been demonstrated to play a pivotal role in early embryonic development. Although the expression of PDGF in the inner ear has been studied by RT-PCR, how PDGFR is involved there remains largely unclear. In the current study, we used the antagonistic anti-PDGFR-beta antibody, APB5, to investigate the role of PDGFR-beta in the neonatal mouse inner ear. PDGFR-beta was detected immunohistochemically in the mesenchymal tissue adjacent to the sensory epithelium of the inner ear, and a ligand for PDGFR-beta was detected around the sensory epithelium. To determine whether this expression plays a functional role, we injected APB5 into neonates to block the function of PDGFR-beta. Mesenchymal tissue defects and abnormal capillaries with irregular shapes, especially in the cochlear lateral wall, were detected in APB5-treated mice. The results of a TUNEL assay revealed that not only the adjacent mesenchymal cells but also the sensory epithelial cells underwent cell death. These results indicate that PDGFR-beta signals are required for the survival of the capillary and mesenchymal cells in the neonatal mouse inner ear and also indirectly implicate these signals in the survival of the sensory epithelium.

Ghrelin inhibits contraction and proliferation of human aortic smooth muscle cells by cAMP/PKA pathway activation

Ghrelin (Ghr), the natural ligand of growth hormone secretagogue receptor, is principally produced by the stomach. An interesting aspect in Ghr cardiovascular effects was elicited by the identification of ghrelin and GHS (growth hormone secretagogue) receptor mRNA expression in several cardiovascular tissues and cell types. In man, Ghr administration induced lowering of blood pressure, and decreased plasma levels were reported in several pathological conditions. The present investigation was performed to elucidate ghrelin effect on contraction and proliferation of human aortic smooth muscle cells (HASMC). Ghrelin receptor expression in HASMC was evaluated by RT-PCR, and binding studies were performed to elucidate the receptor kinetics. Ghr effect on angiotensin II-induced HASMC contraction and proliferation was evaluated in vitro. In addition, involvement of cAMP, ERK, and Akt pathways was investigated. PCR documented GHS-R1a expression. Binding of [(125)I-His(9)]-Ghrelin to HASMC was saturable in a dose-dependent manner. Scatchard analysis showed a single class of binding sites (Kd 1.58+/-0.23nM, B(max) 5848+/-291fmol/10(5) cells). In competition binding, (d-Lys(3))-GHRP-6 showed a capacity to compete with [(125)I-His(9)]-Ghrelin with Ki of 4.25nM. Ghrelin was able to inhibit angiotensin II-induced proliferation and contraction in a dose-response fashion via the cAMP/PKA pathway. Our data document that Ghr affects several HASMC functions, opening the way to consider ghrelin as a possible therapeutic target in many pathological conditions associated with vascular damage and remodelling.

Establishment of novel human dedifferentiated chondrosarcoma cell line with osteoblastic differentiation

Dedifferentiated chondrosarcoma is a rare, highly malignant variant of chondrosarcoma in which a high-grade sarcoma coexists with a low-grade chondroid tumor. We herein review a case of dedifferentiated chondrosarcoma with an osteosarcoma omit component that occurred in the distal femur of a 38-year-old man. We established the cell line (NDCS-1) from a pleural effusion of the metastatic lung tumor. The cell line was characterized by a the G-banded karyotype, polymerase chain reaction (PCR) single-strand conformation polymorphism analysis, spectral karyotyping, and reverse transcriptase PCR (RT-PCR). The tumor exhibited complex karyotypes and a high frequency of chromosomal amplication with p53 mutation. This tumor revealed an osteoblastic and chondroblastic character in vitro and in severe combined immunodeficiency mice. The expression and phosphorylation of platelet-derived growth factor receptor-beta, which seemed to play a major role in the malignant phenotype of chondrosarcoma, was confirmed by RT-PCR and Western blotting. To our knowledge, this is the first report of the establishment of a human dedifferentiated chondrosarcoma.

Growth Factor-Stimulated Mitogen-Activated Kinase (MAPK) Phosphorylation in the Rat Epididymis Is Limited by Segmental Boundaries1

Previous evidence has shown that sperm maturation is the result of successive events that influence sperm cells as they move through different microenvironments from the caput to the cauda epididymis. The physiological basis for the creation and maintenance of specific microenvironments along the epididymis are poorly understood. Anatomically, the epididymis consists of segments or lobules of epididymal tubule separated by connective tissue septa (CTS). The fact that CTS restrict the diffusion of tracer substances between segments and that certain gene expression patterns are segment-specific suggest that segments may represent functional epididymal units. In this report, we have further investigated epididymal segmentation by focusing on the ability of CTS to limit the effect of biologically relevant molecules, in particular epidermal growth factor (EGF), basic fibroblast growth factor (FGF2), and vascular endothelial growth factor A (VEGFA), in Segments 1 and 2 of the rat epididymis. We have demonstrated that these growth factors activate mitogen-activated kinase (MAPK) in both segments studied and that growth factors injected into the interstitial space of these segments in vivo exhibited a stimulatory effect only in the segment into which they were injected, i.e., MAPK activation was not observed in the adjacent segment. This restricting influence of CTS was abrogated by treatment with collagenase. In addition, we demonstrate the expression of selected forms of these growth factors and their receptors in Segments 1 and 2, and identify potential downstream targets. These results suggest that CTS regulate the trophic influences of growth factors and potentially other paracrine molecules, thus creating functionally separate units within the epididymis.

Expression and cellular localization of follicle-stimulating hormone receptor in normal human prostate, benign prostatic hyperplasia and prostate cancer

PURPOSE

FSH, identified as an endogenous product of the prostate, is a glycoprotein with proliferative activity. Increasing evidence of autocrine/paracrine activities of gonadotropins at extragonadal sites led us to investigate the gene expression and cellular localization of FSH-R in normal and diseased human prostates.

MATERIALS AND METHODS

Prostate specimens, including normal gland, BPH, PCa and human androgen refractory (PC3) and androgen dependent (LNCaP) prostate cancer cell lines (European Collection of Cell Cultures, Salisbury, United Kingdom), were analyzed for FSH-R expression by semiquantitative and real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry. We also evaluated cyclic adenosine monophosphate production by cultured PC3 and LNCaP stimulated with human FSH.

RESULTS

Little FSH-R expression was seen in 9 of 13 normal and 8 of 15 BPH specimens. Of 30 PCa samples 21 were FSH-R positive with generally higher expression compared to normal prostate and BPH samples. Real-time reverse transcriptase-polymerase chain reaction of matched normal/tumor pairs confirmed higher FSH-R mRNA expression in PCa. PC3 cells expressed FSH-R, while LNCaP cells were FSH-R negative. FSH-R protein was mainly localized in the glandular epithelium and in some stromal cells in normal prostate, BPH and PCa specimens. PC3 cells expressed FSH-R protein and their treatment with FSH induced a significant increase in cyclic adenosine monophosphate production.

CONCLUSIONS

These results indicate that a subset of PCa expresses FSH-R mRNA and protein at levels higher than those of normal and hyperplastic tissues that express FSH-R. This suggests that FSH might contribute to some cases of PCa via a receptor mediated mechanism.

The makings of maleness: towards an integrated view of male sexual development

As the mammalian embryo develops, it must engage one of the two distinct programmes of gene activity, morphogenesis and organogenesis that characterize males and females. In males, sexual development hinges on testis determination and differentiation, but also involves many coordinated transcriptional, signalling and endocrine networks that underpin the masculinization of other organs and tissues, including the brain. Here we bring together current knowledge about these networks, identify gaps in the overall picture, and highlight the known defects that lead to disorders of male sexual development.

Defective postnatal development of the male reproductive tract in LGR4 knockout mice

The final outcome of tube elongation and branching is to maximize the epithelial exchange surfaces in tubular organs. The molecular and cellular basis of these processes is actively studied in model organs such as mammary glands, liver and kidney, but they remain almost unexplored in the male reproductive tract. Here, we report that the orphan G protein-coupled receptor LGR4/GPR48 plays a role in the postnatal tissue remodeling needed for elongation and convolution of the efferent ducts and epididymis. In LGR4 knockout male mice, tube elongation fails, resulting in a hypoplastic and poorly convoluted tract. Cell proliferation is dramatically reduced in KO affected tissues, providing an explanation to the observed phenotype. Detailed analysis showed that LGR4 inactivation manifests differently in the affected organs. In efferent ducts, immune cells infiltrate the epithelium and reach the lumen, blocking the transit of sperm and testicular fluid. In addition, the hypoplasia and low convolution result in a reduction of the epithelial area involved in liquid reabsorption. Both phenomena contribute in tissue swelling upstream the blockade due to liquid and sperm accumulation, with secondary damaging effects on the germinal epithelium. In the epididymis, the thin and highly convoluted duct is replaced by a large cystic tube which is surrounded by a thick condensation of mesenchymal cells. The abnormal organization of the cellular compartments in and around the ducts suggests that LGR4 might play a role in epithelial-mesenchymal interactions. Altogether, our data identify LGR4 as an important signaling molecule implicated in the tube morphogenesis of the male reproductive tract.

Differential expression and distribution of alternatively spliced transcripts of PDGF-A and of PDGF receptor-alpha in mouse reproductive tissues

Platelet-derived growth factor-A (PDGF-A) affects cellular activities such as proliferation, differentiation, and development by way of paracrine or autocrine interaction with PDGF-A receptor alpha (PDGFR-alpha). Two forms of alternatively spliced PDGF-A mRNA, a long and a short isoform, have been found in several mammalian species. Expression of PDGF-A and its cognate receptor PDGFR-alpha has been well studied in various tissues. However, these investigations did not distinguish between the individual isoforms of PDGF-A. In the present investigation, we identified the differential cellular expression patterns of the two isoforms of PDGF-A and of PDGFR-alpha in mouse reproductive tissues by using laser capture microdissection coupled with reverse transcriptase polymerase chain reaction. The long PDGF-A mRNA isoform was primarily detected in the epithelium, while the short isoform was ubiquitously distributed in epithelium, stroma, and muscle cells, although it was still more prominent in epithelium. PDGFR-alpha was mainly detected in stromal and muscle cells. Also, it was found in the epididymal epithelium, mucosal folds of the seminal vesicle, and ovarian granulosa cells. Thus, the complete PDGF-A/PDGFR-alpha signaling system is present in murine reproductive tissues, but the distribution of the long and short isoforms of PDFG-A differs.

Imatinib Mesylate Inhibits Leydig Cell Tumor Growth: Evidence for In vitro and In vivo Activity

Leydig cell tumors are usually benign tumors of the male gonad. However, if the tumor is malignant, no effective treatments are currently available. Leydig cell tumors express platelet-derived growth factor (PDGF), kit ligand and their respective receptors, PDGFR and c-kit. We therefore evaluated the effects of imatinib mesylate (imatinib), a selective inhibitor of the c-kit and PDGFR tyrosine kinases, on the growth of rodent Leydig tumor cell lines in vivo and in vitro, and examined, in human Leydig cell tumor samples, the expression of activated PDGFR and c-kit and the mutations in exons of the c-kit gene commonly associated with solid tumors. Imatinib caused concentration-dependent decreases in the viability of Leydig tumor cell lines, which coincided with apoptosis and inhibition of proliferation and ligand-stimulated phosphorylation of c-kit and PDGFRs. Mice bearing s.c. allografts of a Leydig tumor cell line treated with imatinib p.o., had an almost complete inhibition of tumor growth, less tumor cell proliferation, increased apoptosis, and a lesser amount of tumor-associated mean vessel density compared with controls. No drug-resistant tumors appeared during imatinib treatment but tumors regrew after drug withdrawal. Human Leydig cell tumors showed an intense expression of the phosphorylated form of c-kit and a less intense expression of phosphorylated PDGFRs. No activating mutations in common regions of mutation of the c-kit gene were found. Our studies suggest that Leydig cell tumors might be a potential target for imatinib therapy.