To elucidate the molecular pathways that modulate renal cyst growth in ADPKD, we performed global gene profiling on cysts of different size (<1 ml, n = 5; 10-20 ml, n = 5; >50 ml, n = 3) and minimally cystic tissue (MCT, n = 5) from five PKD1 human polycystic kidneys using Affymetrix HG-U133 Plus 2.0 arrays. We used gene set enrichment analysis to identify overrepresented signaling pathways and key transcription factors (TFs) between cysts and MCT. We found down-regulation of kidney epithelial restricted genes (e.g. nephron segment-specific markers and cilia-associated cystic genes such as HNF1B, PKHD1, IFT88 and CYS1) in the renal cysts. On the other hand, PKD1 cysts displayed a rich profile of gene sets associated with renal development, mitogen-mediated proliferation, cell cycle progression, epithelial-mesenchymal transition, hypoxia, aging and immune/inflammatory responses. Notably, our data suggest that up-regulation of Wnt/beta-catenin, pleiotropic growth factor/receptor tyrosine kinase (e.g. IGF/IGF1R, FGF/FGFR, EGF/EGFR, VEGF/VEGFR), G-protein-coupled receptor (e.g. PTGER2) signaling was associated with renal cystic growth. By integrating these pathways with a number of dysregulated networks of TFs (e.g. SRF, MYC, E2F1, CREB1, LEF1, TCF7, HNF1B/ HNF1A and HNF4A), our data suggest that epithelial dedifferentiation accompanied by aberrant activation and cross-talk of specific signaling pathways may be required for PKD1 cyst growth and disease progression. Pharmacological modulation of some of these signaling pathways may provide a potential therapeutic strategy for ADPKD.

Glypicans are a family of heparan sulfate proteoglycans that are linked to the cell surface through a glycosyl–phosphatidylinositol anchor. One member of this family, glypican-3 (Gpc3), is mutated in patients with the Simpson-Golabi-Behmel syndrome (SGBS). These patients display pre- and postnatal overgrowth, and a varying range of dysmorphisms. The clinical features of SGBS are very similar to the more extensively studied Beckwith-Wiedemann syndrome (BWS). Since BWS has been associated with biallelic expression of insulin-like growth factor II (IGF-II), it has been proposed that GPC3 is a negative regulator of IGF-II. However, there is still no biochemical evidence indicating that GPC3 plays such a role.Here, we report that GPC3-deficient mice exhibit several of the clinical features observed in SGBS patients, including developmental overgrowth, perinatal death, cystic and dyplastic kidneys, and abnormal lung development. A proportion of the mutant mice also display mandibular hypoplasia and an imperforate vagina. In the particular case of the kidney, we demonstrate that there is an early and persistent developmental abnormality of the ureteric bud/collecting system due to increased proliferation of cells in this tissue element.The degree of developmental overgrowth of the GPC3-deficient mice is similar to that of mice deficient in IGF receptor type 2 (IGF2R), a well characterized negative regulator of IGF-II. Unlike the IGF2R-deficient mice, however, the levels of IGF-II in GPC3 knockouts are similar to those of the normal littermates.

Polycystin-1 (PC1), the product of the PKD1 gene mutated in the majority of autosomal dominant polycystic kidney disease (ADPKD) cases, undergoes a cleavage resulting in the intracellular release of its C-terminal tail (CTT). Here, we demonstrate that the PC1 CTT co-localizes with and binds to beta-catenin in the nucleus. This interaction requires a nuclear localization motif present in the PC1 CTT as well as the N-terminal portion of beta-catenin. The PC1 CTT inhibits the ability of both beta-catenin and Wnt ligands to activate T-cell factor (TCF)-dependent gene transcription, a major effector of the canonical Wnt signaling pathway. The PC1 CTT may produce this effect by reducing the apparent affinity of the interaction between beta-catenin and the TCF protein. DNA microarray analysis reveals that the canonical Wnt signaling pathway is activated in ADPKD patient cysts. Our results suggest a novel mechanism through which PC1 cleavage may impact upon Wnt-dependent signaling and thereby modulate both developmental processes and cystogenesis.

These findings indicate that psychological distress and high stress responses to cancer are prevalent among women with ovarian cancer, suggesting they should be carefully evaluated to determine whether treatment for these symptoms is warranted.

WNT/beta-catenin signaling has an established role in nephron formation during kidney development. Yet, the role of beta-catenin during ureteric morphogenesis in vivo is undefined. We generated a murine genetic model of beta-catenin deficiency targeted to the ureteric bud cell lineage. Newborn mutant mice demonstrated bilateral renal aplasia or renal dysplasia. Analysis of the embryologic events leading to this phenotype revealed that abnormal ureteric branching at E12.5 precedes histologic abnormalities at E13.5. Microarray analysis of E12.5 kidney tissue identified decreased Emx2 and Lim1 expression among a small subset of renal patterning genes disrupted at the stage of abnormal branching. These alterations are followed by decreased expression of genes downstream of Emx2, including Lim1, Pax2, and the ureteric tip markers, c-ret and Wnt 11. Together, these data demonstrate that beta-catenin performs essential functions during renal branching morphogenesis via control of a hierarchy of genes that control ureteric branching.

The kidney of the Gpc3-/ mouse, a novel model of human renal dysplasia, is characterized by selective degeneration of medullary collecting ducts preceded by enhanced cell proliferation and overgrowth during branching morphogenesis. Here, we identify cellular and molecular mechanisms underlying this renal dysplasia. Glypican-3 (GPC3) deficiency was associated with abnormal and contrasting rates of proliferation and apoptosis in cortical (CCD) and medullary collecting duct (MCD) cells. In CCD, cell proliferation was increased threefold. In MCD, apoptosis was increased 16-fold. Expression of Gpc3 mRNA in ureteric bud and collecting duct cells suggested that GPC3 can exert direct effects in these cells. Indeed, GPC3 deficiency abrogated the inhibitory activity of BMP2 on branch formation in embryonic kidney explants, converted BMP7-dependent inhibition to stimulation, and enhanced the stimulatory effects of KGF. Similar comparative differences were found in collecting duct cell lines derived from GPC3-deficient and wild type mice and induced to form tubular progenitors in vitro, suggesting that GPC3 directly controls collecting duct cell responses. We propose that GPC3 modulates the actions of stimulatory and inhibitory growth factors during branching morphogenesis.

*Truncating mutations in Gli3, an intracellular effector in the SHH-SMO-GLI signaling pathway, cause renal aplasia/dysplasia in humans and mice. Yet, the pathogenic mechanisms are undefined. Here, we report the effect of decreased SHH-SMO signaling on renal morphogenesis, the expression of SHH target genes and GLI binding to Shh target genes. Shh deficiency or cyclopaminemediated SMO inhibition disrupted renal organogenesis, decreased expression of GLI1 and GLI2 proteins, but increased expression of GLI3 repressor relative to GLI3 activator. Shh deficiency decreased expression of kidney patterning genes (Pax2 and Sall1) and cell cycle regulators (cyclin D1 and MYCN). Elimination of Gli3 in Shh -/-mice rescued kidney malformation and restored expression of Pax2, Sall1, cyclin D1, MYCN, Gli1 and Gli2. To define mechanisms by which SHH-SMO signaling controls gene expression, we determined the binding of GLI proteins to 5Ј flanking regions containing GLI consensus binding sequences in Shh target genes using chromatin immunoprecipitation. In normal embryonic kidney tissue, GLI1 and/or GLI2 were bound to each target gene. By contrast, treatment of embryonic kidney explants with cyclopamine decreased GLI1 and/or GLI2 binding, and induced binding of GLI3. However, cyclopamine failed to decrease Gli1 and Gli2 expression and branching morphogenesis in Gli3-deficient embryonic kidney tissue. Together, these results demonstrate that SHH-SMO signaling controls renal morphogenesis via transcriptional control of Gli, renal patterning and cell cycle regulator genes in a manner that is opposed by GLI3.

Idiopathic antenatal hydronephrosis (IAHN), defined as antenatal hydronephrosis not associated with other morphologic renal tract abnormalities, is the most common abnormality detected by antenatal ultrasound. We performed a systematic review and meta-analysis to determine the outcome of IAHN. We screened three databases and bibliographies to identify English-language original peer-reviewed papers that reported serial postnatal renal ultrasonography in children with IAHN. Patients who stabilized and/or improved were extracted and pooled according to the individual grading systems used by each study. A systematic analysis of data extracted from 25 articles revealed overall resolution of pelviectasis in milder cases of IAHN (Society of Fetal Urology [SFU] grade 1-2; anterior posterior pelvic diameter [APPD]<12 mm). In contrast, IAHN of higher severity (grades 3-4; APPD>12 mm) resolved with a lower frequency. Meta-analysis of data extracted from seven papers showed stabilization of pelviectasis in 98% of patients with grades 1-2 (95% confidence interval [CI] 0.93-1.0; p =0.0008) and in 51% of patients with grades 3-4 (95% CI 0.34-0.68; p <0.00001). Grades 1-2 pelviectasis was five times more likely to stabilize than grades 3-4 pelviectasis (odds ratio [OR] 4.69; 95% CI 1.73-12.76; p =0.002). We conclude that in patients with IAHN and lesser degrees of pelvic dilatation, pelvic diameter decreases to the normal range or does not worsen with the vast majority of patients. Further studies are needed to define outcomes, particularly in more severe forms of IAHN.