Cryptorchidism in the orl rat is associated with muscle patterning defects in the fetal gubernaculum and altered hormonal signaling

Association of PFKM gene polymorphisms and susceptibility to cryptorchidism in a Chinese Han population

BACKGROUND

Cryptorchidism is one of the most common congenital anomalies in newborn boys. There are various risk factors that have been verified to have relationship with cryptorchidism, including exogenous and genetic, but the pathogenesis of cryptorchidism remains unclear. PFKM gene is a critical gene encodes for a regulatory enzyme, which limits the rate in the pathway of glycolysis. We assumed that cryptorchidism risk may associated with PFKM gene single-nucleotide polymorphisms (SNPs). Thus we selected three tag SNPs in the PFKM gene and aimed to investigate the possible association between PFKM gene polymorphisms and cryptorchidism risk.

METHODS

The SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. 140 cases and 227 controls were enrolled in this study, including 105 unilateral cryptorchidism and 35 bilateral cases. The testis position was decided by the higher one in bilateral cases.

RESULTS

The frequency of allele G of SNP rs2228500 is increased in cryptorchidism patients compared to that in controls (p < 0.05). Genotypic frequencies of rs2228500 are associated with the susceptibility of cryptorchidism in the codominant model (p < 0.05). And compared with G/G genotype in the dominant model, notable decreased frequencies of A carriers (A/G-A/A genotypes) were observed in cryptorchidism patients (p = 0.0069, OR = 1.80, 95% CI  1.17-2.75).

CONCLUSIONS

This research first revealed that PFKM gene polymorphisms were associated with cryptorchidism in a Chinese Han population. We have offered primary evidence that the G allele and the G/G genotype of rs2228500 SNP in the PFKM gene are more frequent in patients with cryptorchidism than healthy controls.

The G-Protein-Coupled Membrane Estrogen Receptor Is Present in Horse Cryptorchid Testes and Mediates Downstream Pathways

Cryptorchidism in horses is a commonly occurring malformation. The molecular basis of this pathology is not fully known. In addition, the origins of high intratesticular estrogen levels in horses remain obscure. In order to investigate the role of the G-protein-coupled membrane estrogen receptor (GPER) and establish histological and biochemical cryptorchid testis status, healthy and cryptorchid horse testes were subjected to scanning electron microscopy analysis, histochemical staining for total protein (with naphthol blue black; NBB), acid content (with toluidine blue O; TBO), and polysaccharide content (with periodic acid-Schiff; PAS). The expression of GPER was analyzed by immunohistochemistry and Western blot. GPER-mediated intracellular cAMP and calcium (Ca2+) signaling were measured immunoenzymatically or colorimetrically. Our data revealed changes in the distribution of polysaccharide content but not the protein and acid content in the cryptorchid testis. Polysaccharides seemed to be partially translocated from the interstitial compartment to the seminiferous tubule compartment. Moreover, the markedly decreased expression of GPER and GPER downstream molecules, cAMP and Ca2+, suggests their potential role in testis pathology. Increased estrogen levels in cryptorchid conditions may be linked to disturbed GPER signaling. We postulate that GPER is a prominent key player in testis development and function and may be used as a new biomarker of horse testis in health and disease.

Maternal smoking during pregnancy and risk of cryptorchidism: a systematic review and meta-analysis

The risk factors for undescended testes in male infants and the underlying pathogenesis still remain unclear. The aim of this study is to identify the relationship between maternal smoking during pregnancy and risk of cryptorchidism. A systematic review was conducted using appropriate search terms to identify articles pertaining to maternal smoking during pregnancy and risk of cryptorchidism. Entries up to December 23, 2017 were taken into consideration, without any language or regional restriction. The crude ORs and their 95% CIs were computed by using the fixed-effect model. Twenty studies involving 111,712 infants were included in our meta-analysis. The risk of having a male infant with cryptorchidism was significantly different between mothers who smoked during pregnancy and those who did not (pooled crude OR 1.18, 95% confidence interval [CI] 1.12-1.24, p < 0.00001).Conclusion: Our findings suggest that smoking during pregnancy increased the risk of cryptorchidism by 1.18 times. Further investigations that are well-designed, multicentric studies measuring variables, such as the number of cigarettes smoked in a day and the stage of pregnancy during which the mothers smoked, are necessary to precisely determine the relationship between maternal smoking and risk of cryptorchidism. What is Known: • Preterm and low birth weight have been definitively shown to be risk factors for cryptorchidism. • The relationship between with maternal smoking during pregnancy and risk of cryptorchidism remains controversial all the time. What is New: • Mothers who smoked during pregnancy had a 1.18 times higher risk of having a child with cryptorchidism as compared to those who did not smoke. • Evidence has been found that maternal smoking during pregnancy is a definitive risk factor for cryptorchidism.

Subphenotype meta-analysis of testicular cancer genome-wide association study data suggests a role for RBFOX family genes in cryptorchidism susceptibility

STUDY QUESTION

Can subphenotype analysis of genome-wide association study (GWAS) data from subjects with testicular germ cell tumor (TGCT) provide insight into cryptorchidism (undescended testis, UDT) susceptibility?

SUMMARY ANSWER

Suggestive intragenic GWAS signals common to UDT, TGCT case-case and TGCT case-control analyses occur in genes encoding RBFOX RNA-binding proteins (RBPs) and their neurodevelopmental targets.

WHAT IS KNOWN ALREADY

UDT is a strong risk factor for TGCT, but while genetic risk factors for TGCT are well-known, genetic susceptibility to UDT is poorly understood and appears to be more complex.

STUDY DESIGN, SIZE, DURATION

We performed a secondary subphenotype analysis of existing GWAS data from the Testicular Cancer Consortium (TECAC) and compared these results with our previously published UDT GWAS data, and with data previously acquired from studies of the fetal rat gubernaculum.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Studies from the National Cancer Institute (NCI), United Kingdom (UK) and University of Pennsylvania (Penn) that enrolled white subjects were the source of the TGCT GWAS data. We completed UDT subphenotype case-case (TGCT/UDT vs TGCT/non-UDT) and case-control (TGCT/UDT vs control), collectively referred to as 'TECAC' analyses, followed by a meta-analysis comprising 129 TGCT/UDT cases, 1771 TGCT/non-UDT cases, and 3967 unaffected controls. We reanalyzed our UDT GWAS results comprising 844 cases and 2718 controls by mapping suggestive UDT and TECAC signals (defined as P < 0.001) to genes using Ingenuity Pathway Analysis (IPA®). We compared associated pathways and enriched gene categories common to all analyses after Benjamini-Hochberg multiple testing correction, and analyzed transcript levels and protein expression using qRT-PCR and rat fetal gubernaculum confocal imaging, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

We found suggestive signals within 19 genes common to all three analyses, including RBFOX1 and RBFOX3, neurodevelopmental paralogs that encode RBPs targeting (U)GCATG-containing transcripts. Ten of the 19 genes participate in neurodevelopment and/or contribute to risk of neurodevelopmental disorders. Experimentally predicted RBFOX gene targets were strongly overrepresented among suggestive intragenic signals for the UDT (117 of 628 (19%), P = 3.5 × 10-24), TECAC case-case (129 of 711 (18%), P = 2.5 × 10-27) and TECAC case-control (117 of 679 (17%), P = 2 × 10-21) analyses, and a majority of the genes common to all three analyses (12 of 19 (63%), P = 3 × 10-9) are predicted RBFOX targets. Rbfox1, Rbfox2 and their encoded proteins are expressed in the rat fetal gubernaculum. Predicted RBFOX targets are also enriched among transcripts differentially regulated in the fetal gubernaculum during normal development (P = 3 × 10-31), in response to in vitro hormonal stimulation (P = 5 × 10-45) and in the cryptorchid LE/orl rat (P = 2 × 10-42).

LARGE SCALE DATA

GWAS data included in this study are available in the database of Genotypes and Phenotypes (dbGaP accession numbers phs000986.v1.p1 and phs001349.v1p1).

LIMITATIONS, REASONS FOR CAUTION

These GWAS data did not reach genome-wide significance for any individual analysis. UDT appears to have a complex etiology that also includes environmental factors, and such complexity may require much larger sample sizes than are currently available. The current methodology may also introduce bias that favors false discovery of larger genes.

WIDER IMPLICATIONS OF THE FINDINGS

Common suggestive intragenic GWAS signals suggest that RBFOX paralogs and other neurodevelopmental genes are potential UDT risk candidates, and potential TGCT susceptibility modifiers. Enrichment of predicted RBFOX targets among differentially expressed transcripts in the fetal gubernaculum additionally suggests a role for this RBP family in regulation of testicular descent. As RBFOX proteins regulate alternative splicing of Calca to generate calcitonin gene-related peptide, a protein linked to development and function of the gubernaculum, additional studies that address the role of these proteins in UDT are warranted.

STUDY FUNDING/COMPETING INTEREST(S)

The Eunice Kennedy Shriver National Institute for Child Health and Human Development (R01HD060769); National Center for Research Resources (P20RR20173), National Institute of General Medical Sciences (P20GM103464), Nemours Biomedical Research, the Testicular Cancer Consortium (U01CA164947), the Intramural Research Program of the NCI, a support services contract HHSN26120130003C with IMS, Inc., the Abramson Cancer Center at Penn, National Cancer Institute (CA114478), the Institute of Cancer Research, UK and the Wellcome Trust Case-Control Consortium (WTCCC) 2. None of the authors reports a conflict of interest.

Insulin-Like Peptide 3 (INSL3) Serum Concentration During Human Male Fetal Life

Context: Insulin-like peptide 3 (INSL3), a protein hormone produced by Leydig cells, may play a crucial role in testicular descent as male INSL3 knockout mice have bilateral cryptorchidism. Previous studies have measured human fetal INSL3 levels in amniotic fluid only. Objective: To measure INSL3 serum levels and mRNA in fetal umbilical cord blood and fetal testes, respectively. Design: INSL3 concentrations were assayed on 50 μl of serum from male human fetal umbilical cord blood by a non-commercial highly sensitive and specific radioimmunoassay. For secondary confirmation, quantitative real-time PCR was used to measure INSL3 relative mRNA expression in 7 age-matched human fetal testes. Setting: UT Southwestern Medical Center, Dallas, TX and Medical University of South Carolina, Charleston, SC. Patients or other Participants: Twelve human male umbilical cord blood samples and 7 human male testes were obtained from fetuses 14-21 weeks gestation. Male sex was verified by leukocyte genomic DNA SRY PCR. Interventions: None. Main Outcome Measures: Human male fetal INSL3 cord blood serum concentrations and testicular relative mRNA expression. Results: INSL3 serum concentrations during human male gestational weeks 15-20 were 2-4 times higher than published prepubertal male levels and were 5-100 times higher than previous reports of INSL3 concentrations obtained from amniotic fluid. Testicular fetal INSL3 mRNA relative expression was low from weeks 14-16, rose significantly weeks 17 and 18, and returned to low levels at week 21. Conclusions: These findings further support the role of INSL3 in human testicular descent and could prove relevant in uncovering the pathophysiology of cryptorchidism.

Postnatal Changes in Testicular Position Are Associated With IGF-I and Function of Sertoli and Leydig Cells

CONTEXT

Despite clinical guidelines calling for repetitive examination of testicular position during childhood, little is known of normal changes in testicular position during childhood, let alone factors that control it.

OBJECTIVE

To assess changes in and factors associated with testicular position during childhood.

DESIGN

Testicular position (the distance from the pubic bone to the upper pole of the testes) at birth, 3 months, 18 months, 36 months, and 7 years and reproductive hormones at 3 months were measured.

SETTING

Prenatally recruited, prospective longitudinal birth cohort.

PARTICIPANTS

A total of 2545 boys were recruited prenatally in a Danish-Finnish birth cohort and had a testicular position examination available. A subset of 680 Danish and 362 Finnish boys had serum reproductive hormone concentrations and insulin-like growth factor I (IGF-I) determined at 3 months.

MAIN OUTCOME MEASURES

Testicular distance to pubic bone (TDP), serum reproductive hormone, and IGF-I concentrations.

RESULTS

TDP increased from birth to 3 months and decreased thereafter. Length, gestational age, weight for gestational age, and penile length were positively associated with larger TDP and thus lower testicular position in a linear mixed-effect model. Furthermore, IGF-I concentration, inhibin B/follicle-stimulating hormone ratio, and testosterone/luteinizing hormone ratio were all independently and positively associated with longer TDP.

CONCLUSIONS

We provide longitudinal data on postnatal changes in TDP. TDP is dynamic and associated with Leydig and Sertoli cell function as well as with IGF-I levels during the first months of life at mini-puberty of infancy. TDP may thus be a useful biomarker of postnatal testicular function.

Regional Variation in Androgen Receptor Expression and Biomechanical Properties May Contribute to Cryptorchidism Susceptibility in the LE/orl Rat

Background: The process of testicular descent requires androgen and insulin-like 3, hormones secreted by fetal Leydig cells. Knowledge concerning distinct and common functions of these hormones in regulating development of the fetal gubernaculum remains limited and/or conflicting. The current studies were designed to better define characteristics of androgen receptor (AR) expression, function and regulation, as well as the biomechanical properties of normal and cryptorchid gubernaculum during fetal development. Methods: We studied fetal gubernacula from Long Evans outbred (LE/wt) rats and an inbred (LE/orl) strain with an inherited form of cryptorchidism associated with an AR signaling defect. Gubernacular cells or whole organs obtained from LE/wt and LE/orl fetal gubernacula underwent AR immunostaining and quantitative image analysis. The effects of dihydrotestosterone (DHT) on AR expression, muscle fiber morphology, hyaluronan (HA) levels and glycosaminoglycan (GAG) content were measured in LE/wt gubernacula. Finally, the spatial mechanics of freshly harvested LE/wt and LE/orl fetal gubernacula were compared using micropipette aspiration. Results: AR is expressed in the nucleus of mesenchymal core, tip and cord cells of the embryonic (E) day 17 and 21 fetal gubernaculum, and is enhanced by DHT in primary cultures of gubernacular mesenchymal cells. Enhanced AR expression at the tip was observed in LE/wt but not LE/orl gubernacula. In in vitro studies of whole mount fetal gubernaculum, DHT did not alter muscle fiber morphology, HA content or GAG production. Progressive swelling with reduced cellular density of the LE/wt gubernaculum at E19-21 was associated with increased central stiffness in LE/wt but not in LE/orl fetuses. Conclusions: These data confirm nuclear AR expression in gubernacular mesenchyme with distal enhancement at the tip/cord region in LE/wt but not LE/orl rat fetuses. DHT enhanced cellular AR expression but had no major effects on muscle morphology or matrix composition in the rat fetal gubernaculum in vitro. Regional increased stiffness and decreased cell density between E19 and E21 were observed in LE/wt but not LE/orl fetal gubernacula. Developmental differences in cell-specific AR expression in LE/orl fetal gubernacula may contribute to the dysmorphism and aberrant function that underlies cryptorchidism susceptibility in this strain.

Diethylstilbestrol regulates mouse gubernaculum testis cell proliferation via PLC-Ca2+ -CREB pathway

Recent evidence suggested a positive correlation between environmental estrogens (EEs) and high incidence of abnormalities in male urogenital system, but the mechanism remains unclear. Diethylstilbestrol (DES) is a nonsteroidal synthetic estrogen that disrupts the morphology and proliferation of gubernaculum testis cells, but the underlying mechanism is unclear. In this study, mouse gubernaculum testis cells were pretreated with phospholipase C (PLC) inhibitor U-73122 and then treated with DES. The results demonstrated that U-73122 impaired DES-evoked intracellular Ca2+ mobilization in gubernaculum testis cells and inhibited DES-induced proliferation of gubernaculum testis cells. Mechanistically, we found that U-73122 inhibited DES-induced activation of cAMP-response element binding protein (CREB) in gubernaculum testis cells. In conclusion, these data suggest that the effects of DES on mouse gubernaculum testis cells are mediated by PLC-Ca²⁺ -CREB pathway.

SIGNIFICANCE OF THE STUDY

Environmental estrogens remain a serious threat to male reproductive health, and it is important to understand the mechanism by which EEs affect the male productive system. Here we explore potential mechanisms how the proliferation and contractility of gubernaculum testis cells are regulated by diethylstilbestrol. Our findings provide the first evidence that PLC-Ca²⁺ -CREB signalling pathway mediates the nongenomic effects of diethylstilbestrol on gubernaculum testis cells. These findings provide new insight into the role of diethylstilbestrol in the aetiology of male reproductive dysfunction and will help develop better approaches for the prevention and therapy of male reproductive malformation.

Perspective: A Neuro-Hormonal Systems Approach to Understanding the Complexity of Cryptorchidism Susceptibility

Nonsyndromic cryptorchidism is a common multifactorial, condition with long-term risks of subfertility and testicular cancer. Revealing the causes of cryptorchidism will likely improve prediction and prevention of adverse outcomes. Herein we provide our current perspective of cryptorchidism complexity in a synthesis of cumulative clinical and translational data generated by ourselves and others. From our recent comparison of genome-wide association study (GWAS) data of cryptorchidism with or without testicular germ cell tumor, we identified RBFOX family genes as candidate susceptibility loci. Notably, RBFOX proteins regulate production of calcitonin gene-related peptide (CGRP), a sensory neuropeptide linked to testicular descent in animal models. We also re-analyzed existing fetal testis transcriptome data from a rat model of inherited cryptorchidism (the LE/orl strain) for enrichment of Leydig cell progenitor genes. The majority are coordinately downregulated, consistent with known reduced testicular testosterone levels in the LE/orl fetus, and similarly suppressed in the gubernaculum. Using qRT-PCR, we found dysregulation of dorsal root ganglia (DRG) sensory transcripts ipsilateral to undescended testes. These data suggest that LE/orl cryptorchidism is associated with altered signaling in possibly related cell types in the testis and gubernaculum as well as DRG. Complementary rat and human studies thus lead us to propose a multi-level, integrated neuro-hormonal model of testicular descent. Variants in genes encoding RBFOX family proteins and/or their transcriptional targets combined with environmental exposures may disrupt this complex pathway to enhance cryptorchidism susceptibility. We believe that a systems approach is necessary to provide further insight into the causes and consequences of cryptorchidism.

Identification of Differentially Expressed Genes in Pelvic Organ Prolapse by RNA-Seq

Background

Pelvic organ prolapse (POP) brings major health issues for women, affecting 40% of postmenopausal women, and directly affects bladder and bowel function, as well as quality of life. In light of the projected growth in demand for care for pelvic floor disorders, determining the etiology and progression of POP has important public health implications.

Material/Methods

Uterosacral ligaments (USLs) samples of POP patients and normal controls were enrolled for RNA-Seq, and functional annotation analysis and Protein-Protein interaction (PPI) networks construction were performed for differentially expressed genes (DEGs).

Results

A total of 81 DEGs were identified between POP and normal control, and distinctly classify all samples into normal and POP group by hierarchical clustering. Sixty-six DEGs demonstrated the same expression pattern among the POP samples with different stages. For those DEGs, canonical Wnt receptor signaling pathway was the most significantly enriched GO term (P value=3.33E-07), and neuroactive ligand-receptor interaction was the most significantly enriched pathway (P value=1.24E-03). In The PPI networks of 81 dysregulated genes, significant hub proteins contained TOP2A (Degree=54), KCNA5 (Degree=22) and PLA2G2A (Degree=19), suggesting their important role in the development of POP.

Conclusions

This RNA-seq analysis identified a POP signature of 81 genes, and some ECM-related genes, including COMP, NDP, and SNAI2 might participate in the pathology of POP and be applied as potential therapeutic targets.

The Male Fetal Biomarker INSL3 Reveals Substantial Hormone Exchange between Fetuses in Early Pig Gestation

The peptide hormone INSL3 is uniquely produced by the fetal testis to promote the transabdominal phase of testicular descent. Because it is fetal sex specific, and is present in only very low amounts in the maternal circulation, INSL3 acts as an ideal biomarker with which to monitor the movement of fetal hormones within the pregnant uterus of a polytocous species, the pig. INSL3 production by the fetal testis begins at around GD30. At GD45 of the ca. 114 day gestation, a time at which testicular descent is promoted, INSL3 evidently moves from male to female allantoic compartments, presumably impacting also on the female fetal circulation. At later time-points (GD63, GD92) there is less inter-fetal transfer, although there still appears to be significant INSL3, presumably of male origin, in the plasma of female fetuses. This study thus provides evidence for substantial transfer of a peptide hormone between fetuses, and probably also across the placenta, emphasizing the vulnerability of the fetus to extrinsic hormonal influences within the uterus.

Polygenic inheritance of cryptorchidism susceptibility in the LE/orl rat

STUDY HYPOTHESIS

Susceptibility to inherited cryptorchidism in the LE/orl rat may be associated with genetic loci that influence developmental patterning of the gubernaculum by the fetal testis.

STUDY FINDING

Cryptorchidism in the LE/orl rat is associated with a unique combination of homozygous minor alleles at multiple loci, and the encoded proteins are co-localized with androgen receptor (AR) and Leydig cells in fetal gubernaculum and testis, respectively.

WHAT IS KNOWN ALREADY

Prior studies have shown aberrant perinatal gubernacular migration, muscle patterning defects and reduced fetal testicular testosterone in the LE/orl strain. In addition, altered expression of androgen-responsive, cytoskeletal and muscle-related transcripts in the LE/orl fetal gubernaculum suggest a role for defective AR signaling in cryptorchidism susceptibility.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

The long-term LE/orl colony and short-term colonies of outbred Crl:LE and Crl:SD, and inbred WKY/Ncrl rats were maintained for studies. Animals were intercrossed (LE/orl X WKY/Ncrl), and obligate heterozygotes were reciprocally backcrossed to LE/orl rats to generate 54 F2 males used for genotyping and/or linkage analysis. At least five fetuses per gestational time point from two or more litters were used for quantitative real-time RT-PCR (qRT-PCR) and freshly harvested embryonic (E) day 17 gubernaculum was used to generate conditionally immortalized cell lines. We completed genotyping and gene expression analyses using genome-wide microsatellite markers and single nucleotide polymorphism (SNP) arrays, PCR amplification, direct sequencing, restriction enzyme digest with fragment analysis, whole genome sequencing (WGS), and qRT-PCR. Linkage analysis was performed in Haploview with multiple testing correction, and qRT-PCR data were analyzed using ANOVA after log transformation. Imaging was performed using custom and commercial antibodies directed at candidate proteins in gubernaculum and testis tissues, and gubernaculum cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

LE/orl rats showed reduced fertility and fecundity, and higher risk of perinatal death as compared with Crl:LE rats, but there were no differences in breeding outcomes between normal and unilaterally cryptorchid males. Linkage analysis identified multiple peaks, and with selective breeding of outbred Crl:LE and Crl:SD strains for alleles within two of the most significant (P < 0.003) peaks on chromosomes 6 and 16, we were able to generate a non-LE/orl cryptorchid rat. Associated loci contain potentially functional minor alleles (0.25-0.36 in tested rat strains) including an exonic deletion in Syne2, a large intronic insertion in Ncoa4 (an AR coactivator) and potentially deleterious variants in Solh/Capn15, Ankrd28, and Hsd17b2. Existing WGS data indicate that homozygosity for these combined alleles does not occur in any other sequenced rat strain. We observed a modifying effect of the Syne2(del) allele on expression of other candidate genes, particularly Ncoa4, and for muscle and hormone-responsive transcripts. The selected candidate genes/proteins are highly expressed, androgen-responsive and/or co-localized with developing muscle and AR in fetal gubernaculum, and co-localized with Leydig cells in fetal testis.

LIMITATIONS, REASONS FOR CAUTION

The present study identified multiple cryptorchidism-associated linkage peaks in the LE/orl rat, containing potentially causal alleles. These are strong candidate susceptibility loci, but further studies are needed to demonstrate functional relevance to the phenotype.

WIDER IMPLICATIONS OF THE FINDINGS

Association data from both human and rat models of spontaneous, nonsyndromic cryptorchidism support a polygenic etiology of the disease. Both the present study and a human genome-wide association study suggest that common variants with weak effects contribute to susceptibility, and may exist in genes encoding proteins that participate in AR signaling in the developing gubernaculum. These findings have potential implications for the gene-environment interaction in the etiology of cryptorchidism.

LARGE SCALE DATA

Sequences were deposited in the Rat Genome Database (RGD, http://rgd.mcw.edu/).

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by: R01HD060769 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), 2P20GM103446 and P20GM103464 from the National Institute of General Medical Sciences (NIGMS), and Nemours Biomedical Research. The authors have no competing interests to declare.

Fetal Rat Gubernaculum Mesenchymal Cells Adopt Myogenic and Myofibroblast-Like Phenotypes

PURPOSE

Gubernaculum-cremaster complex development is hormonally regulated and abnormal in a cryptorchid rat model. Using cell tracking techniques and imaging we studied myogenic phenotypes and fates in the fetal rat gubernaculum-cremaster complex.

MATERIALS AND METHODS

Embryonic day 17 gubernaculum-cremaster complexes were labeled with CellTracker™ or the DNA synthesis marker EdU (5-ethynyl-2'-deoxyuridine), or immobilized in Matrigel® and grown in culture. Embryonic day 17 to 21 gubernaculum-cremaster complex sections and cells were imaged using wide field and deconvolution immunofluorescence microscopy, and muscle and/or myofibroblast specific antibodies. Deconvolved image stacks were used to create a 3-dimensional model of embryonic day 21 gubernaculum-cremaster complex muscle.

RESULTS

PAX7 (paired box 7) positive and myogenin positive muscle precursors were visible in a desmin-rich myogenic zone between muscle layers that elongated and became thicker during development. Gubernaculum-cremaster complex inner mesenchymal cells expressed desmin and αSMA (α smooth muscle actin) at lower levels than in the myogenic zone. After pulse labeling with CellTracker or EdU mesenchymal cells became incorporated into differentiated muscle. Conversely, mesenchymal cells migrated beyond Matrigel immobilized gubernaculum-cremaster complexes, expressed PAX7 and fused to form striated myotubes. Mesenchymal gubernaculum-cremaster complex cell lines proliferated more than 40 passages and showed contractile behavior but did not form striated muscle. Our 3-dimensional gubernaculum-cremaster complex model had 2 orthogonal ventral layers and an arcing inner layer of muscle.

CONCLUSIONS

Our data suggest that mesenchymal cells in the peripheral myogenic zone of the fetal gubernaculum-cremaster complex contribute to formation of a distinctively patterned cremaster muscle. Nonmyogenic, desmin and αSMA positive gubernaculum-cremaster complex mesenchymal cells proliferate and have a myofibroblast-like phenotype in culture. Intrinsic mechanical properties of these divergent cell types may facilitate perinatal inversion of the gubernaculum-cremaster complex.

Pathway analysis supports association of nonsyndromic cryptorchidism with genetic loci linked to cytoskeleton-dependent functions

STUDY QUESTION

What are the genetic loci that increase susceptibility to nonsyndromic cryptorchidism, or undescended testis?

SUMMARY ANSWER

A genome-wide association study (GWAS) suggests that susceptibility to cryptorchidism is heterogeneous, with a subset of suggestive signals linked to cytoskeleton-dependent functions and syndromic forms of the disease.

WHAT IS KNOWN ALREADY

Population studies suggest moderate genetic risk of cryptorchidism and possible maternal and environmental contributions to risk. Previous candidate gene analyses have failed to identify a major associated locus, although variants in insulin-like 3 (INSL3), relaxin/insulin-like family peptide receptor 2 (RXFP2) and other hormonal pathway genes may increase risk in a small percentage of patients.

STUDY DESIGN, SIZE, DURATION

This is a case-control GWAS of 844 boys with nonsyndromic cryptorchidism and 2718 control subjects without syndromes or genital anomalies, all of European ancestry.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All boys with cryptorchidism were diagnosed and treated by a pediatric specialist. In the discovery phase, DNA was extracted from tissue or blood samples and genotyping performed using the Illumina HumanHap550 and Human610-Quad (Group 1) or OmniExpress (Group 2) platform. We imputed genotypes genome-wide, and combined single marker association results in meta-analyses for all cases and for secondary subphenotype analyses based on testis position, laterality and age, and defined genome-wide significance as P = 7 × 10(-9) to correct for multiple testing. Selected markers were genotyped in an independent replication group of European cases (n = 298) and controls (n = 324). We used several bioinformatics tools to analyze top (P < 10(-5)) and suggestive (P < 10(-3)) signals for significant enrichment of signaling pathways, cellular functions and custom gene lists after multiple testing correction.

MAIN RESULTS AND THE ROLE OF CHANCE

In the full analysis, we identified 20 top loci, none reaching genome-wide significance, but one passing this threshold in a subphenotype analysis of proximal testis position (rs55867206, near SH3PXD2B, odds ratio = 2.2 (95% confidence interval 1.7, 2.9), P = 2 × 10(-9)). An additional 127 top loci emerged in at least one secondary analysis, particularly of more severe phenotypes. Cytoskeleton-dependent molecular and cellular functions were prevalent in pathway analysis of suggestive signals, and may implicate loci encoding cytoskeletal proteins that participate in androgen receptor signaling. Genes linked to human syndromic cryptorchidism, including hypogonadotropic hypogonadism, and to hormone-responsive and/or differentially expressed genes in normal and cryptorchid rat gubernaculum, were also significantly overrepresented. No tested marker showed significant replication in an independent population. The results suggest heterogeneous, multilocus and potentially multifactorial susceptibility to nonsyndromic cryptorchidism.

LIMITATIONS, REASONS FOR CAUTION

The present study failed to identify genome-wide significant markers associated with cryptorchidism that could be replicated in an independent population, so further studies are required to define true positive signals among suggestive loci.

WIDER IMPLICATIONS OF THE FINDINGS

As the only GWAS to date of nonsyndromic cryptorchidism, these data will provide a basis for future efforts to understand genetic susceptibility to this common reproductive anomaly and the potential for additive risk from environmental exposures.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by R01HD060769 (the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD)), P20RR20173 (the National Center for Research Resources (NCRR), currently P20GM103464 from the National Institute of General Medical Sciences (NIGMS)), an Institute Development Fund to the Center for Applied Genomics at The Children's Hospital of Philadelphia, and Nemours Biomedical Research. The authors have no competing interests to declare.

Evaluation and management of the infant with cryptorchidism

PURPOSE OF REVIEW

Normal testicular descent is now recognized to occur in two steps with the first, transabdominal stage controlled by insulin-like hormone 3. The second, inguinoscrotal stage is controlled by androgens, mostly indirectly via the genitofemoral nerve, which appears to direct the migration of the gubernaculum to the scrotum. Undescended testis (UDT) is multifactorial, with only some of the genes identified. This review highlights recent developments that are leading to changes in practice.

RECENT FINDINGS

There is an emerging consensus among pediatric surgeons and urologists about the management of UDT with recommendations that the diagnosis of congenital UDT should be confirmed at 3-6 months of age and orchidopexy done at 6-12 months of age. With the recommendations for early surgery, recent studies focus on the complications of orchidopexy, to determine whether this is higher in infants than older children. In addition, there is general acceptance of the existence of 'acquired' UDT, which develops after about 2 years of age, but treatment for this group remains controversial.

SUMMARY

Evaluation of children with UDT now needs to be separated into the assessment of possible congenital UDT in infants at 0-6 months, for orchidopexy before 12 months, and preschool boys, who may be developing acquired UDT.

Diethylstilbestrol affects the expression of GPER in the gubernaculum testis

Recent evidence suggested a positive correlation between environmental estrogens (EEs) and high incidence of abnormalities in male urogenital system. EEs are known to cause the abnormalities of testes development and testicular descent. Diethylstilbestrol (DES) is a nonsteroidal synthetic estrogen that disrupts the morphology and proliferation of gubernacular cells, and its nongenomic effects on gubernaculum testis cells may be mediated by G protein-coupled estrogen receptor (GPER). In this study, we detected the expression of GPER in mouse gubernacular testis and investigated the effects of DES on the expression of GPER in gubernaculum testis cells. RT-PCR analysis revealed that GPER mRNA was expressed in the gubernaculum. GPER protein was detected in the parenchymal cells of the gubernaculum early in development. Furthermore, we demonstrate that GPER inhibitor G15 relieved DES-induced inhibition of GPER expression in gubernaculum testis cell, but ER inhibitor ICI 182780 had the converse effects on DES-induced inhibition of GPER expression in these cells. These data suggest that the effects of DES on mouse gubernaculum testis cells are mediated at least partially by the regulation of GPER expression.

Phenotype specific association of the TGFBR3 locus with nonsyndromic cryptorchidism

PURPOSE

Based on a genome-wide association study of testicular dysgenesis syndrome showing a possible association with TGFBR3, we analyzed data from a larger, phenotypically restricted cryptorchidism population for potential replication of this signal.

MATERIALS AND METHODS

We excluded samples based on strict quality control criteria, leaving 844 cases and 2,718 controls of European ancestry that were analyzed in 2 separate groups based on genotyping platform (ie Illumina® HumanHap550, version 1 or 3, or Human610-Quad, version 1 BeadChip in group 1 and Human OmniExpress 12, version 1 BeadChip platform in group 2). Analyses included genotype imputation at the TGFBR3 locus, association analysis of imputed data with correction for population substructure, subsequent meta-analysis of data for groups 1 and 2, and selective genotyping of independent cases (330) and controls (324) for replication. We also measured Tgfbr3 mRNA levels and performed TGFBR3/betaglycan immunostaining in rat fetal gubernaculum.

RESULTS

We identified suggestive (p ≤ 1× 10(-4)) association of markers in/near TGFBR3, including rs9661103 (OR 1.40; 95% CI 1.20, 1.64; p = 2.71 × 10(-5)) and rs10782968 (OR 1.58; 95% CI 1.26, 1.98; p = 9.36 × 10(-5)) in groups 1 and 2, respectively. In subgroup analyses we observed strongest association of rs17576372 (OR 1.42; 95% CI 1.24, 1.60; p = 1.67 × 10(-4)) with proximal and rs11165059 (OR 1.32; 95% CI 1.15, 1.38; p = 9.42 × 10(-4)) with distal testis position, signals in strong linkage disequilibrium with rs9661103 and rs10782968, respectively. Association of the prior genome-wide association study signal (rs12082710) was marginal (OR 1.13; 95% CI 0.99, 1.28; p = 0.09 for group 1), and we were unable to replicate signals in our independent cohort. Tgfbr3/betaglycan was differentially expressed in wild-type and cryptorchid rat fetal gubernaculum.

CONCLUSIONS

These data suggest complex or phenotype specific association of cryptorchidism with TGFBR3 and the gubernaculum as a potential target of TGFβ signaling.