Muscle-Invasive Bladder Cancer With Hydronephrosis Exhibits a High Frequency of Mutations in Fibroblast Growth Factor Receptor 3 Gene.

BACKGROUND/AIM: Recent studies have reported conflicting findings regarding the significance of hydronephrosis (HN) in muscle-invasive bladder cancer (MIBC). The molecular characteristics of MIBC with HN are unclear, therefore, we aimed to address the gaps in previous research and elucidate HN's molecular significance in patients with MIBC. MATERIALS AND METHODS: Clinical, genetic, and imaging information on bladder cancer patients enrolled in The Cancer Genome Atlas were obtained from public databases to analyze the association between the presence of hydronephrosis and genetic alterations and molecular subtyping. A total of 108 patients who underwent total cystectomy for MIBC at the Hiroshima University Hospital were enrolled in the study to verify the association between HN and renal function with patient prognosis. RESULTS: We observed a statistically significant difference in the distribution of molecular subtypes (p=0.0146). The proportion of patients with the luminal papillary subtype was approximately twice as high in patients with HN (48.8%) than in those without HN (25.0%). The mutation frequency of fibroblast growth factor receptor (FGFR) 3 was approximately three-fold higher in patients with HN (20.9%) than in those without HN (7.1%). Multivariate analysis, which considered HN and estimated glomerular filtration rate as confounding factors in our MIBC cohort, revealed that reduced renal function, but not HN, was an independent predictor for overall survival. CONCLUSION: MIBC presenting HN exhibits a high frequency of mutations in the FGFR3 gene. In addition, not HN itself, but reduced renal function due to HN may worsen the prognosis for MIBC.

Prenatal Detection of a FOXF1 Deletion in a Fetus with ACDMPV and Hydronephrosis.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal lung developmental disorder caused by the arrest of fetal lung formation, resulting in neonatal death due to acute respiratory failure and pulmonary arterial hypertension. Heterozygous single-nucleotide variants or copy-number variant (CNV) deletions involving the FOXF1 gene and/or its lung-specific enhancer are found in the vast majority of ACDMPV patients. ACDMPV is often accompanied by extrapulmonary malformations, including the gastrointestinal, cardiac, or genitourinary systems. Thus far, most of the described ACDMPV patients have been diagnosed post mortem, based on histologic evaluation of the lung tissue and/or genetic testing. Here, we report a case of a prenatally detected de novo CNV deletion (~0.74 Mb) involving the FOXF1 gene in a fetus with ACDMPV and hydronephrosis. Since ACDMPV is challenging to detect by ultrasound examination, the more widespread implementation of prenatal genetic testing can facilitate early diagnosis, improve appropriate genetic counselling, and further management.

Comparative transcriptome analysis of miRNA in hydronephrosis male children caused by ureteropelvic junction obstruction with or without renal functional injury.

MicroRNAs (miRNAs or miRs) are non-coding RNAs that contribute to pathological processes of various kidney diseases. Renal function injury represents a final common outcome of congenital obstructive nephropathy and has attracted a great deal of attention. However the molecular mechanisms are still not fully established. In this study, we compared transcriptome sequencing data of miRNAs of renal tissues from congenital hydronephrosis children with or without renal functional injury, in order to better understand whether microRNAs could play important roles in renal functional injury after ureteropelvic junction obstruction. A total of 22 microRNAs with significant changes in their expression were identified. Five microRNAs were up-regulated and 17 microRNAs were down-regulated in the renal tissues of the hydronephrosis patients with renal function injury compared with those without renal function injury. MicroRNA target genes were predicted by three major online miRNA target prediction algorithms, and all these mRNAs were used to perform the gene ontology analysis and Kyoto Encyclopedia of Gene and Genomes pathway analysis. Then, twelve candidate human and rat homologous miRNAs were selected for validation using RT-qPCR in vitro and in vivo; only miR-187-3p had a trend identical to that detected by the sequencing results among the human tissues, in vivo and in vitro experimental models. In addition, we found that the change of miR-187-3p in vivo was consistent with results in vitro models and showed a decrease trend in time dependence. These results provided a detailed catalog of candidate miRNAs to investigate their regulatory role in renal injury of congenital hydronephrosis, indicating that they may serve as candidate biomarkers or therapeutic targets in the future.

Novel ALG12 variants and hydronephrosis in siblings with impaired N-glycosylation.

BACKGROUND: ALG12-CDG is a rare autosomal recessive type I congenital disorder of glycosylation (CDG) due to pathogenic variants in ALG12 which encodes the dolichyl-P-mannose:Man-7-GlcNAc-2-PP-dolichyl-alpha-6-mannosyltransferase. Thirteen patients from unrelated 11 families have been reported, most of them result in broad multisystem manifestations with clinical variability. It is important to validate abnormal glycosylation to establish causal relationship. CASE REPORT: Here, we report two siblings with novel compound heterozygous variants in ALG12: c.443T>C, p.(Leu148Pro) and c.412_413insCGT, p.(Gln137_Phe138insSer). Both patients showed global developmental delay, microcephaly, hypotonia, failure to thrive, facial dysmorphism, skeletal malformations and coagulation abnormalities, which are common in ALG12-CDG. In addition, one of our patients showed left hydronephrosis, which is a novel clinical feature in ALG12-CDG. Brain MRI showed hypoplasia of cerebrum, brain stem and cerebellar vermis in both patients. N-glycosylation defects of trypsin digested transferrin peptides were revealed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and electrospray ionization MS verified the lack of N-glycans in transferrin. CONCLUSIONS: The present study can add hydronephrosis to phenotypic spectrum of ALG12-CDG. Since the symptoms of ALG12-CDG are quite diverse, the combination of whole-exome sequencing and transferrin glycopeptide analysis with MS, can help diagnosis of ALG12-CDG.

The genotype and phenotype of chromosome 18p deletion syndrome: Case series.

RATIONALE: The chromosome 18p deletion syndrome is a syndrome with a deletion of all or a portion of the short arm of the chromosome 18. The phenotypes of the chromosome 18p deletion syndrome vary widely among individuals due to differences in size and breakpoints and the involved genes on the deletions. Given the varied and untypical clinical presentation of this syndrome, the prenatal diagnosis of the syndrome still presents as a challenge. PATIENT CONCERNS: We described 4 China cases with different chromosomal breakpoints. In case 1, a woman who with mild phenotypes gave birth to a severely deformed fetus. Three other cases were for prenatal diagnosis. Their phenotypes are the increased nuchal translucency (INT) and the noninvasive prenatal testing (NIPT) indicated deletions on the chromosome 18p and severe hydronephrosis respectively. DIAGNOSIS: The 4 cases were diagnosed with chromosome 18p deletion syndrome through karyotype analysis and array-based comparative genomic hybridization (array-CGH). INTERVENTIONS: Karyotype analysis and array-based comparative genomic hybridization were used to analyze the abnormal chromosome. OUTCOMES: Case 1 and case 2 revealed 11.51 and 12.39 Mb deletions in 18p11.32p11.21. Case 3 revealed 7.1 Mb deletions in 18p11.3218p11.23. Case 4 revealed 9.9 Mb deletions in 18p11.3218p11.22. LESSONS: In our report, we are the first to report that mother and progeny who have the same chromosomal breakpoint have different phenotypes, significantly. In addition, we found a new phenotype of chromosome 18p deletion syndrome in fetus, which can enrich the phenotypes of this syndrome in the prenatal diagnosis. Finally, we demonstrate that the individuals with different chromosomal breakpoints of 18p deletion syndrome have different phenotypes. On the other hand, the individuals with the same chromosomal breakpoints of 18p deletion syndrome may also have remarkably different phenotypes.

Mid-trimester absent nasal bone and transient unilateral hydronephrosis associated with 16p13.3 microduplication.

Characteristic phenotypic features of 16p13.3 microduplication include impaired mental development, arthrogryposis-like musculoskeletal anomalies (club-feet, congenital hip dislocation, and camptodactyly of fingers and toes), facial dysmorphology, and at times congenital cardiac disease. Most of the described affected individuals have microduplications involving the CREBBP gene. Findings indicate this gene to be dosage-sensitive and likely involved in the phenotypes of 16p13.3 microduplication syndrome. We describe the incidental finding of 16p13.3 microduplication in a fetus with mid-trimester sonographic examination showing absent nasal bone and transient unilateral hydronephrosis.

Consistent alteration of chain length-specific ceramides in human and mouse fibrotic kidneys.

BACKGROUND: Several studies revealed alterations of single sphingolipid species, such as chain length-specific ceramides, in plasma and serum of patients with kidney diseases. Here, we investigated whether such alterations occur in kidney tissue from patients and mice suffering from renal fibrosis, the common endpoint of chronic kidney diseases. METHODS: Human fibrotic kidney samples were collected from nephrectomy specimens with hydronephrosis and/or pyelonephritis. Healthy parts from tumor nephrectomies served as nonfibrotic controls. Mouse fibrotic kidney samples were collected from male C57BL/6J mice treated with an adenine-rich diet for 14 days or were subjected to 7 days of unilateral ureteral obstruction (UUO). Kidneys of untreated mice and contralateral kidneys (UUO) served as respective controls. Sphingolipid levels were detected by LC-MS/MS. Fibrotic markers were analyzed by TaqMan® analysis and immunohistology. RESULTS: Very long-chain ceramides Cer d18:1/24:0 and Cer d18:1/24:1 were significantly downregulated in both fibrotic human kidney cortex and fibrotic murine kidney compared to respective control samples. These effects correlate with upregulation of COL1α1, COL3α1 and αSMA expression in fibrotic human kidney cortex and fibrotic mouse kidney. CONCLUSION: We have shown that very long-chain ceramides Cer d18:1/24:0 and Cer d18:1/24:1 are consistently downregulated in fibrotic kidney samples from human and mouse. Our findings support the use of in vivo murine models as appropriate translational means to understand the involvement of ceramides in human kidney diseases. In addition, our study raises interesting questions about the possible manipulation of ceramide metabolism to prevent progression of fibrosis and the use of ceramides as potential biomarkers of chronic kidney disease.

Prenatal diagnosis and management of monozygotic twins discordant for severe fetal abnormalities.

OBJECTIVE: We present prenatal diagnosis and management of monozygotic (MZ) twins discordant for severe fetal abnormalities. CASE REPORT: A 36-year-old woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age, and hydrops fetalis, a giant cystic hygroma of 5 × 3.5 cm and left hydronephrosis in a co-twin. The other co-twin was structurally normal. Amniocentesis revealed a karyotype of 46,XY in both co-twins. Simultaneous polymorphic DNA marker analysis using the DNAs extracted from maternal blood and uncultured amniocytes confirmed MZ twinning. The woman underwent a successful selective fetal reduction by radiofrequency ablation at 22 weeks of gestation. At 28 weeks of gestation, premature rupture of membranes occurred, and a 1280-g normal male baby and a 275-g dead malformed co-twin were delivered. The normal co-twin was phenotypically normal and was doing well at age seven weeks. CONCLUSIONS: Prenatal diagnosis of MZ twins discordant for structural abnormalities should include a differential diagnosis of MZ twinning, and a zygosity test is necessary under such a circumstance.

A long-term study of the effects of SLC12A1 homozygous mutation (g.62382825G>A, p.Pro372Leu) in Japanese Black cattle.

Recessive missense mutation in the solute carrier family 12, member 1 (SLC12A1) gene (g.62382825G>A) is associated with hydrallantois, which is the accumulation of fluid in the allantoic cavity of a pregnant animal, and usually causes fetal death in Japanese Black cattle. However, the symptoms of a homozygote with this mutation that do not result in fetal death have not previously been tracked and evaluated. In the present study, we observed a homozygote with the SLC12A1 risk allele over a long-term period. The calf did not show any obvious clinical symptoms, although it did exhibit a slight growth retardation that accompanied mild calciuria. At 28 months of age, the homozygote showed renal dysfunction, which in turn resulted in hydronephrosis. The time course of the symptoms was consistent with the phenotype of Bartter syndrome in humans. Additionally, the risk heterozygous genotype did not any effects on carcass traits, which indicates that eliminating the risk allele would not have any unfavorable effects. Therefore, we emphasize that both the fetal- and late-stage symptoms associated with the SLC12A1 risk allele compromise animal welfare, and consequently may result in severe economic losses for individual farmers if the SLC12A1 risk allele is not eliminated from the population.

Duplex kidney formation: developmental mechanisms and genetic predisposition.

Congenital abnormalities of the kidney and urinary tract (CAKUT) are a highly diverse group of diseases that together belong to the most common abnormalities detected in the new-born child. Consistent with this diversity, CAKUT are caused by mutations in a large number of genes and present a wide spectrum of phenotypes. In this review, we will focus on duplex kidneys, a relatively frequent form of CAKUT that is often asymptomatic but predisposes to vesicoureteral reflux and hydronephrosis. We will summarise the molecular programs responsible for ureter induction, review the genes that have been identified as risk factors in duplex kidney formation and discuss molecular and cellular mechanisms that may lead to this malformation.

Pathogenic copy number variants are detected in a subset of patients with gastrointestinal malformations.

BACKGROUND: Gastrointestinal atresias and urological defects are main causes of pediatric surgery in infants. As copy number variants (CNVs) have been shown to be involved in the development of congenital malformations, the aim of our study was to investigate the presence of CNVs in patients with gastrointestinal and urological malformations as well as the possibility of tissue-specific mosaicism for CNVs in the cohort. METHODS: We have collected tissue and/or blood samples from 25 patients with anorectal malformations, esophageal atresia, or hydronephrosis, and screened for pathogenic CNVs using array comparative genomic hybridization (array-CGH). RESULTS: We detected pathogenic aberrations in 2/25 patients (8%) and report a novel possible susceptibility region for esophageal atresia on 15q26.3. CNV analysis in different tissues from the same patients did not reveal evidence of tissue-specific mosaicism. CONCLUSION: Our study shows that it is important to perform clinical genetic investigations, including CNV analysis, in patients with congenital gastrointestinal malformations since this leads to improved information to families as well as an increased understanding of the pathogenesis.

Cathepsin S regulates renal fibrosis in mouse models of mild and severe hydronephrosis.

As a member of the cysteine protease family, cathepsin S (CTSS) serves an important role in diseases such as cancer, arthritis and atherosclerosis. Nevertheless, its role in renal fibrosis is unknown. In the present study, the effects of CTSS on renal fibrosis in mild (group M) and severe (group S) hydronephrosis were studied by reverse transcription­-quantitative PCR (RT­qPCR), western blot analysis (WB), Masson's trichrome staining and immunohistochemical staining in mouse models. The effects of CTSS on extracellular matrix (ECM) deposition and epithelial­mesenchymal transition (EMT) and the potential mechanisms were further studied by RT­qPCR and WB in transforming growth factor (TGF­ß1)­stimulated TCMK­1 cells. Compared with group N (no hydronephrosis), the expression levels of CTSS in the M and S groups were significantly higher, and a significant increase in ECM deposition was observed in the S group. In addition, compared with group N, the expression levels of TGF­ß1, α­smooth muscle actin (α­SMA), SMAD2, SMAD3, phosphorylated (p)SMAD2 and pSMAD3 in groups M and S were significantly higher, whereas the expression of E­cadherin was significantly lower. Inhibition of CTSS expression increased the expression levels of TGF­ß1, α­SMA, fibronectin, collagen­I, SMAD2, SMAD3, pSMAD2 and pSMAD3, whereas E­cadherin expression decreased. A significant increase in CTSS was observed in the TGF­ß1­stimulated TCMK­1 cell line. ECM deposition and EMT were also intensified. The opposite outcomes occurred after intervention with small interfering RNA targeting CTSS. In conclusion, CTSS affected EMT and the deposition of ECM. CTSS may mediate the regulation of fibrosis by the TGF­ß/SMAD signaling pathway. CTSS may serve an important role in the treatment of renal fibrosis.

Okamoto syndrome has features overlapping with Au-Kline syndrome and is caused by HNRNPK mutation.

Okamoto syndrome is characterized by severe intellectual disability, generalized hypotonia, stenosis of the ureteropelvic junction with hydronephrosis, cardiac anomalies, and characteristic facial gestalt. Several patients have been reported. The basic mechanism of Okamoto syndrome has not been clarified. Au-Kline syndrome is a new syndrome due to loss-of-function variants in the HNRNPK (heterogeneous nuclear ribonucleoprotein K) gene. A new patient with Okamoto syndrome visited our hospital. We noticed that the patient had features overlapping with Au-Kline syndrome. We studied the HNRNPK gene by Sanger sequencing, and identified a novel splicing variant. We suggest that Okamoto syndrome is identical to Au-Kline syndrome.

Significance of AHR nuclear translocation sequence in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cPLA2α activation and hydronephrosis.

The aryl hydrocarbon receptor (AHR) plays a major role in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity phenotypes. TCDD bound to AHR elicits both genomic action in which target genes are transcriptionally upregulated and nongenomic action in which cytosolic phospholipase A2α (cPLA2α) is rapidly activated. However, how either of these actions, separately or in combination, induces toxicity phenotypes is largely unknown. In this study, we used AHRnls/nls mice as a model in which AHR was mutated to lack nuclear translocation sequence (NLS), and AHRd/- mice as the corresponding control. Using this model, we studied TCDD-induced alterations in cPLA2α activation and related factors because of the pivotal roles of cPLA2α both in AHR's nongenomic action and in regulation of causative genes of TCDD-induced hydronephrosis. Dams were orally administered TCDD at a dose of 300 µg/kg body weight on postnatal day 1, and pups subsequently exposed to TCDD via milk were examined for gene expression on PND 7 and for histological changes on PND 14. The activation of the AHR genomic action and hydronephrosis onset were observed in the control group but not in the AHRnls/nls group. An ex vivo experiment using peritoneal macrophages exposed to 100 nM TCDD resulted in rapid activation of cPLA2α, an indicator of the nongenomic action, only in the control group but not in the AHRnls/nls group. These results indicated that an NLS is required for the AHR's genomic and nongenomic actions.

Changes in cell fate determine the regenerative and functional capacity of the developing kidney before and after release of obstruction.

Congenital obstructive nephropathy is a major cause of chronic kidney disease (CKD) in children. The contribution of changes in the identity of renal cells to the pathology of obstructive nephropathy is poorly understood. Using a partial unilateral ureteral obstruction (pUUO) model in genetically modified neonatal mice, we traced the fate of cells derived from the renal stroma, cap mesenchyme, ureteric bud (UB) epithelium, and podocytes using Foxd1Cre, Six2Cre, HoxB7Cre, and Podocyte.Cre mice respectively, crossed with double fluorescent reporter (membrane-targetted tandem dimer Tomato (mT)/membrane-targetted GFP (mG)) mice. Persistent obstruction leads to a significant loss of tubular epithelium, rarefaction of the renal vasculature, and decreased renal blood flow (RBF). In addition, Forkhead Box D1 (Foxd1)-derived pericytes significantly expanded in the interstitial space, acquiring a myofibroblast phenotype. Degeneration of Sine Oculis Homeobox Homolog 2 (Six2) and HoxB7-derived cells resulted in significant loss of glomeruli, nephron tubules, and collecting ducts. Surgical release of obstruction resulted in striking regeneration of tubules, arterioles, interstitium accompanied by an increase in blood flow to the level of sham animals. Contralateral kidneys with remarkable compensatory response to kidney injury showed an increase in density of arteriolar branches. Deciphering the mechanisms involved in kidney repair and regeneration post relief of obstruction has potential therapeutic implications for infants and children and the growing number of adults suffering from CKD.

Fryl deficiency is associated with defective kidney development and function in mice.

FRY like transcription coactivator ( Fryl) gene located on chromosome 5 is a paralog of FRY microtubule binding protein ( Fry) in vertebrates. It encodes a protein with unknown functions. Fryl gene is conserved in various species ranging from eukaryotes to human. Although there are several reports on functions of Fry gene, functions of Fryl gene remain unclear. A mouse line containing null mutation in Fryl gene by gene trapping was produced in this study for the first time. The survival and growth of Fryl-/- mice were observed. Fryl gene expression levels in mouse tissues were determined and histopathologic analyses were conducted. Most Fryl-/- mice died soon after birth. Rare Fryl-/- survivors showed growth retardation with significantly lower body weight compared to their littermate controls. Although they could breed, more than half of Fryl-/- survivors died of hydronephrosis before age 1. No abnormal histopathologic lesion was apparent in full-term embryo or adult tissues except the kidney. Abnormal lining cell layer detachments from walls of collecting and convoluted tubules in kidneys were apparent in Fryl-/- neonates and full-term embryos. Fryl gene was expressed in renal tubular tissues including the glomeruli and convoluted and collecting tubules. This indicates that defects in tubular systems are associated with Fryl functions and death of Fryl-/- neonates. Fryl protein is required for normal development and functional maintenance of kidney in mice. This is the first report of in vivo Fryl gene functions. Impact statement FRY like transcription coactivator ( Fryl) gene is conserved in various species ranging from eukaryotes to human. It expresses a protein with unknown function. We generated a Fryl gene mutant mouse line and found that most homozygous mice died soon after their birth. Rare Fryl-/- survivors showed growth retardation with significantly lower body weight compared to their littermate controls. Although they could breed, more than half of Fryl-/- survivors died of hydronephrosis before age 1. Full-term mutant embryos showed abnormal collecting and convoluted tubules in kidneys where Fryl gene was expressed. Collectively, these results indicate that Fryl protein is required for normal development and functional maintenance of kidney in mice. To the best of our knowledge, this is the first report on in vivo Fryl gene functions.

Silencing of SOCS-1 and SOCS-3 suppresses renal interstitial fibrosis by alleviating renal tubular damage in a rat model of hydronephrosis.

Our study was performed to elucidate how SOCS-1/3 silencing suppresses renal interstitial fibrosis (RIF) by alleviating renal tubular damage in rat models affected by hydronephrosis. Male Wistar rats were randomly selected to establish hydronephrosis rat model, after which all rats were classified into normal, model, negative control (NC), siRNA-SOCS-1, siRNA-SOCS-3, and siRNA-SOCS-1 + siRNA-SOCS-3 groups. The levels of urine protein, serum creatinine (Scr), and blood urea nitrogen (BUN) were detected. ELISA was performed to determine levels of cystatin (CysC), ß2-microglobulin (ß2-MG), interleukin (IL)-6, and tumor necrosis factor (TNF)-α. RT-qPCR and Western blotting were used for mRNA and protein expressions of SOCS-1, SOCS-3, α-smooth muscle actin (α-SMA), and transforming Growth Factor (TGF)-ß1. Compared with the normal group, the levels of Scr, BUN, urine protein, NAG, CysC, ß2-MG, IL-6, and TNF-α were increased in other groups, as well as elevated mRNA and protein expressions of SOCS-1, SOCS-3, α-SMA, and TGF-ß1. The siRNA-SOCS-1, siRNA-SOCS-3, and siRNA-SOCS-1 + siRNA-SOCS-3 groups were found with decreased levels of Scr, BUN, urine protein, NAG, CysC, ß2-MG, IL-6, and TNF-α, as well as mRNA and protein expressions of SOCS-1, SOCS-3, α-SMA, and TGF-ß1, including positive rates of SOCS-1 and SOCS-3 proteins in comparison with the model and NC groups. In comparison with the siRNA-SOCS-1 and siRNA-SOCS-3 groups, the siRNA-SOCS-1 + siRNA-SOCS-3 group exhibited decreased levels of Scr, BUN, urine protein, NAG, CysC, ß2-MG, IL-6, and TNF-α. Our study demonstrated that silencing of SOCS-1/3 may suppress RIF by alleviating the renal tubular damage in rat models affected by hydronephrosis.

Activated Hedgehog-GLI Signaling Causes Congenital Ureteropelvic Junction Obstruction.

Intrinsic ureteropelvic junction obstruction is the most common cause of congenital hydronephrosis, yet the underlying pathogenesis is undefined. Hedgehog proteins control morphogenesis by promoting GLI-dependent transcriptional activation and inhibiting the formation of the GLI3 transcriptional repressor. Hedgehog regulates differentiation and proliferation of ureteric smooth muscle progenitor cells during murine kidney-ureter development. Histopathologic findings of smooth muscle cell hypertrophy and stroma-like cells, consistently observed in obstructing tissue at the time of surgical correction, suggest that Hedgehog signaling is abnormally regulated during the genesis of congenital intrinsic ureteropelvic junction obstruction. Here, we demonstrate that constitutively active Hedgehog signaling in murine intermediate mesoderm-derived renal progenitors results in hydronephrosis and failure to develop a patent pelvic-ureteric junction. Tissue obstructing the ureteropelvic junction was marked as early as E13.5 by an ectopic population of cells expressing Ptch2, a Hedgehog signaling target. Constitutive expression of GLI3 repressor in Ptch1-deficient mice rescued ectopic Ptch2 expression and obstructive hydronephrosis. Whole transcriptome analysis of isolated Ptch2+ cells revealed coexpression of genes characteristic of stromal progenitor cells. Genetic lineage tracing indicated that stromal cells blocking the ureteropelvic junction were derived from intermediate mesoderm-derived renal progenitors and were distinct from the smooth muscle or epithelial lineages. Analysis of obstructive ureteric tissue resected from children with congenital intrinsic ureteropelvic junction obstruction revealed a molecular signature similar to that observed in Ptch1-deficient mice. Together, these results demonstrate a Hedgehog-dependent mechanism underlying mammalian intrinsic ureteropelvic junction obstruction.

Urinary bladder hypertrophy characteristic of male ROMK Bartter's mice does not occur in female mice.

The renal outer medullary potassium channel (ROMK; Kir1.1) plays an important role in Na+ and K+ homeostasis. ROMK knockout (KO) mice show a similar phenotype to Bartter's syndrome of salt wasting and dehydration due to reduced Na-2Cl-K-cotransporter activity but not in ROMK1 KO mice. ROMK KO mice also show hydronephrosis; however, the mechanism of this phenotype has not been understood. We have previously demonstrated a gender-sex difference in hydronephrosis and PGE2 production in ROMK KO mice. In this study we compared the gender-sex difference in bladder hypertrophy and hydronephrosis in ROMK KO mice. The bladder weight, bladder capacity, and the thickness of urothelium in male ROMK KO showed average increased two to approximately fourfold greater than wild-type (WT) mice, but there was no difference in either female or ROMK1 KO mice. The thickness of the urothelium was 648.8 ± 33.2 µm vs. 302.7 ± 16.5 µm ( P < 0.001) and the detrusor muscle 1,940.7 ± 98.9 µm vs. 1,308.2 ± 102.1 µm ( P = 0.013), respectively, in 12-mo male ROMK KO mice compared with the same age WT mice. Western blotting detected ROMK expression at 45~48 kDa, and both ROMK1 and ROMK2 mRNA were detected by quantitative PCR in the bladder. Immunofluorescence staining showed ROMK stained in the bladder, ureter, and urethra in WT but not in KO. In addition, there was a correlation between the severity of hydronephrosis and the bladder weight in male but not in female ROMK KO mice. In conclusion, ROMK expressed in the urinary tract at both protein and mRNA levels; significant enlargement and hypertrophy of the bladder may contribute to hydronephrosis in male ROMK KO mice.