Project description:Introduction and objectives: Proper In utero Wolffian duct (WD) development requires androgens and is essential to epididymis formation and male fertility. However, non-hormonal factors that control WD homeostasis and development remain largely unknown. In this study, we investigated the contribution of Hedgehog signaling pathway to Wolffian duct development by combining pharmacological approaches on organotypic cultures of WD with microarray profiling. Methods: WD were collected from embryos isolated from 16.5 days post-coitum pregnant mice and cultured in air-liquid condition at 37oC during 72 hours in the presence of either: 1) Cyclopamine (25 µM): Hh inhibitor; 2) Smoothened agonist (0.5 µM ; SAG): Hh activator; 3) Culture media (control). WD pictures were taken and analyzed on ImageJ. At the end of the culture, WD were snap-frozen to perform transcriptomic microarray analyses. Three to four biological replicates per condition, i.e. control (n=3), SAG (n=4) and cyclopamine (n=3), were used for microarray analyses. The quality of the RNA was determined using an Agilent BioAnalyzer (Agilent Technologies, Santa Clara, CA, USA) and displayed a RIN ranging from 9.10 to 9.60 out of 10 for the different samples. Microarray analyses were carried out on Affymetrix Mouse Clariom S arrays (Thermofisher) according to the Affymetrix standard protocol. In brief, 100 ng total RNA samples were labeled using the GeneChip® WT Plus Reagent Kit protocol and hybridized to the arrays as described by the manufacturer (Affymetrix, Thermofisher). The cRNA hybridization cocktail was incubated overnight at 45°C while rotating in a hybridization oven. After a 16-h hybridization period, the cocktail was removed and the arrays were washed and stained in an Affymetrix GeneChip fluidics station 450, according to the Affymetrix-recommended protocol. The arrays were scanned using the Affymetrix GCS 3000 7G and Gene-Chip Command Console Software (AGCC) (Affymetrix, Thermofisher) to produce the probe cell intensity data (CEL). The imaged data were then analyzed using the Affymetrix Expression Console Software to perform the quality control, background subtraction and normalization of probe set intensities using Robust Multiarray Analysis (RMA). Microarray processing was performed by the Gene Expression Core facility of the Genomic platform of the Centre Hospitalier Universitaire de Quebec Research Center. The microarray CEL files were imported and analyzed with Transcriptome Analysis Console (TAC) Software 4.0.2 (Applied Biosystems), and submitted to RMA normalization. Samples were included within three different treatment groups (control, SAG and cyclopamine) and compared by Analysis of Variance. Principal Component Analysis and heat maps were performed with Partek Pathway (Partek Incorporated). Biological pathways analyses were performed by using 5 distinct algorithms (i.e. DAVID, STRING, GOrilla, Metascape, GSEA and BLAST2GO). Conclusion: The data made available on GEO repository provide new insights regarding the mechanisms that control epididymis morphogenesis and male fertility. Financially supported by a CIHR grant to CB.
Project description:The Wolffian or mesonephric duct is the embryonic primordium that gives rise to the epididymis, vas deferens and seminal vesicle. The androgen action in the Wolffian duct mesenchyme during fetal development is the predominant driver for Wolffian duct maintenance which is critical for male fertility. However, the androgen’s capability of promoting Wolffian duct maintenance was completely lost in the absence of Wnt9b in mice. In this study, we followed up with this interesting phenomenon and elucidated cellular and molecular mechanisms whereby Wnt9b facilitates Wolffian duct maintenance in male embryos. Wnt9b belongs to the WNT family of secreted proteins and is expressed in the Wolffian duct epithelium. We found that the Wolffian duct degeneration in Wnt9b-/- male embryos was accompanied with decreased cell proliferation in the epithelium but not in the mesenchyme during sexual differentiation. Wnt9b deletion did not impair testicular androgen synthesis but altered expression pattern of mesenchymal androgen receptor. The percentage of androgen receptor positive cells in the mesenchyme was significantly reduced, which can be the cause of decreased epithelial proliferation. Wnt9b actions can be transduced by both β-catenin-dependent and β-catenin-independent pathways in the context of target cells. Transcriptomic analysis of E12.5 Wnt9b+/+ and Wnt9b-/- mesonephroi revealed that expression of multiple WNT/β-catenin-target genes was reduced in the absence of Wnt9b. Deletion of mesenchymal β-catenin led to caudal Wolffian duct degeneration and cystic formation in the cranial region. Taken together, our study uncovers the important WNT9B-AR signaling axis mediating the epithelial-mesenchymal interaction in Wolffian duct development.
Project description:Wolffian/epididymal duct morphogenesis highly coordinates with its specialized function of providing microenvironment for sperm maturation. Without normal development of Wolffian duct, male infertility will result. Therefore, it is important to understand the cellular and molecular mechanisms that regulated Wolffian duct morphogenesis. Our previous study showed that mediolateral intercalation of epithelial cells was a major driver of ductal elongation. In addition, radial intercalation of mesenchymal cells surrounding the duct also played roles in Wolffian duct morphogenesis, and all of these cell re-arrangements were regulated by protein tyrosine kinase 7 (PTK7), a member of the planar cell polarity (PCP) non-canonical Wnt pathway. In this study, we showed that PTK7 regulated assemblies of extracellular matrix (ECM) at the basement membrane and throughout the mesenchyme. Abnormal assembly of laminin, collagen IV, and nephronectin at the basement membrane and fibrosis-like deposition of fibrilla collagen in the interstitium were observed in Ptk7 knockout Wolffian ducts. Meanwhile, PTK7 regulated activity levels of small GTPase RAC1 and myosin II in the mesenchyme of the Wolffian duct. Activity levels of RAC1 and myosin II decreased in the Ptk7 knockout mesenchyme compared to controls. When in-vitro-cultured Wolffian ducts were treated with collagenase IV, cross-link of fibrilla collagen was reduced, Wolffian duct elongation and coiling was reduced significantly, and cyst-like bulge was developed in the epithelial duct. When Wolffian ducts were treated with RAC1 inhibitor NSC23766, fibrilla collagen in the mesenchyme was disassembled, and Wolffian duct elongation was suppressed significantly. Our finding suggested that PTK7 regulated ECM assembly in the mesenchyme likely through regulating RAC1 and myosin II activities. Dynamic assembly and remodeling of ECM were important to Wolffian duct morphogenesis.
Project description:Precursors for the male and female reproductive tracts (also known as the Wolffian duct and the Müllerian duct) co-exist in a mammalian embryo before sexual differentiation. The Wolffian duct and Müllerian duct are surrounded by their own mesenchymes in the mesonephros, which can be distinguished by their specific expression of Gli1 and Amhr2, respectively. In the XX embryo, during sexual differentiation, the Wolffian duct degenerates. In this study, by tracking the fate of the Gli1+ Wolffian duct mesenchyme in the tamoxifen inducible genetic lineage tracing model Gli1-CreER; Rosa-Tomato, we demonstrate that the Wolffian duct mesenchyme does not regress along with the Wolffian duct epithelium in the XX embryo. Instead, the Wolffian duct mesenchyme is repurposed and becomes a unique mesenchymal population in the female reproductive tract. Profiling the transcriptomes and chromatin accessibilities of the Gli1+ Wolffian duct mesenchyme in XX and XY during sexual differentiation (E14.5 and E16.5) shows signaling pathways and transcriptional factors that potentially involves the female and male fate differentiation of the Gli1+ Wolffian duct mesenchyme. Comparing the transcriptomes between the Gli1+ Wolffian duct mesenchyme and the Amhr2+ Müllerian duct mesenchyme from the neonatal uterus reveals similarities and differences between the two mesenchymal populations in the female reproductive tract. Ex vivo ablation of the Wolffian duct mesenchyme stunted the growth of the fetal female reproductive tract. In summary, our discovery of the contribution of the Wolffian duct mesenchyme to the female reproductive tract provides new insights into our understanding of sexual differentiation of reproductive tracts.
Project description:The bladder’s remarkable regenerative capacity in response to injury had been thought to reside exclusively in its basal and intermediate cells. While examining consequences of DNA methyltransferase 1 (Dnmt1) inactivation in mouse embryonic bladder epithelium, we made the surprising discovery that Wolffian duct epithelial cells also support bladder regeneration. Conditional inactivation of Dnmt1 in mouse urethral and bladder epithelium triggered widespread apoptosis, depleted basal and intermediate bladder cells and disrupted Uroplakin protein expression. These events coincided with recruitment of Wolffian duct epithelial cells into Dnmt1 mutant urethra and bladder where they were reprogrammed to express bladder markers including FOXA1, Keratin 5, P63 and Uroplakin. This is the first evidence that Wolffian duct epithelial cells can be summoned in vivo to replace damaged bladder epithelium and function as a cell reservoir for bladder regeneration.
Project description:Sivakumar2011 - Hedgehog Signaling Pathway
This is the current model for the Hedgehog signaling pathway. The best data for mechanism of signaling has been worked out in Drosophila, so this model is based largely on Drosophila data. Hedgehog target genes vary from tissue to tissue, so the identities of individual target genes have not been listed. The main difference between the Drosophila and mammalian Hedgehog signaling pathways is the fact that there are three mammalian homologs of Cubitus interruptus, Gli1 Gli2 and Gli3. Some or all of the mammalian homologs may be proteolytically processed, but the data are controversial. There are two mammalian Ptc genes and three mammalian Hedgehog genes as well. The pathway for Sonic Hedgehog appears to be most similar to the Drosophila hedgehog pathway.
References:
Hedgehog signaling in animal development: paradigms and principles.
Sonic hedgehog in the nervous system: functions, modifications and mechanisms.
Hedgehog signal transduction: recent findings.
Hedgehog signaling: Costal-2 bridges the transduction gap.
This model is described in the article:
A systems biology approach to model neural stem cell regulation by notch, shh, wnt, and EGF signaling pathways.
Sivakumar KC, Dhanesh SB, Shobana S, James J, Mundayoor S.
Omics: a Journal of Integrative Biology. 2011; 15(10):729-737
Abstract:
The Notch, Sonic Hedgehog (Shh), Wnt, and EGF pathways have long been known to influence cell fate specification in the developing nervous system. Here we attempted to evaluate the contemporary knowledge about neural stem cell differentiation promoted by various drug-based regulations through a systems biology approach. Our model showed the phenomenon of DAPT-mediated antagonism of Enhancer of split [E(spl)] genes and enhancement of Shh target genes by a SAG agonist that were effectively demonstrated computationally and were consistent with experimental studies. However, in the case of model simulation of Wnt and EGF pathways, the model network did not supply any concurrent results with experimental data despite the fact that drugs were added at the appropriate positions. This paves insight into the potential of crosstalks between pathways considered in our study. Therefore, we manually developed a map of signaling crosstalk, which included the species connected by representatives from Notch, Shh, Wnt, and EGF pathways and highlighted the regulation of a single target gene, Hes-1, based on drug-induced simulations. These simulations provided results that matched with experimental studies. Therefore, these signaling crosstalk models complement as a tool toward the discovery of novel regulatory processes involved in neural stem cell maintenance, proliferation, and differentiation during mammalian central nervous system development. To our knowledge, this is the first report of a simple crosstalk map that highlights the differential regulation of neural stem cell differentiation and underscores the flow of positive and negative regulatory signals modulated by drugs.
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Project description:The overall goal of this project is to characterize the repertoire of miRNAs in E10.5 Tbx18-expressing peri-wolffian duct stroma cells during development. To achieve this, E10.5 peri-wolffian ducts were dissected from timed-mated Tbx18-Cre;CAG-tdTomato embryos, followed by FACS sorting based on RFP expression to enrich for Tbx18-expressing cells.
Project description:The morphogen Indian Hedgehog plays a very important role during intestinal embryogenesis, but also maintains homeostasis in the adult gut. Intestinal Hedgehog is expressed by the intestinal epithelium and signals in paracrine manner to fibroblasts in the stromal compartment. We studied the colonic changes upon activation of the Hedgehog pathway by deleting the Hedgehog receptor Patched1 in order to alleviate its repressive function.
Project description:Colorectal cancer is one of the most common cancers worldwide with increasing incidence, the presence of metastasis is one of the major causes for poor outcome. BEX2 has been reported to be involved in tumor development in several types of cancer, but is poorly understood in metastatic colorectal cancer. Here we demonstrated that knockout of BEX2 resulted in the enhancement of the migratory and metastatic potential of colorectal cancer cells in vivo and in vitro, re-expression of BEX2 in knockout cells could reverse the migratory enhancement. Expression profile chip indicated that hedgehog signaling pathway was activated after knockout of BEX2, and hedgehog Signaling inhibitor GANT61 and GDC-0449 could somehow reverse the migratory enhancement of BEX2-/- colorectal cancer cells. We also demonstrated that it is the nucleus translocation of Zic2 after BEX2 silenced, that activated hedgehog signaling pathway, while knockdown Zic2 could also abrogated migratory enhancement of BEX2-/- cells. In summary, our findings suggest that BEX2 is a negative modulator of hedgehog signaling pathway by retaining Zic2 in the cytoplasm of colorectal cancer cells, thus to inhibit colorectal cancer cell migration and metastasis.