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: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.
This model is hosted on BioModels Database and identified by: BIOMD0000000395.
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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.
Project description:Background. Primary cilia (PC) are solitary antennae present at the cell surface. These non-motile cilia play an important role in organ development and tissue homeostasis through the transduction of the Hedgehog (Hh) signaling pathway. We recently revealed the presence of PC in the epithelium of the developing epididymis, an organ of the male reproductive system whose dysfunction triggers male infertility. Acknowledging that systemic blockade of the Hh pathway trigger epididymal dysfunctions in vivo, our main goals were 1) to portray the epididymal Hh environment, 2) to determine the direct responsiveness of epididymal epithelial cells to Hh, and 3) to define the contribution of PC to the transduction of this pathway. Results. The Hh ligands Indian and Sonic hedgehog (Ihh and Shh) were respectively located in principal and clear cells of the mouse epididymis by immunofluorescent staining. The propensity of epididymal principal cells to respond to Hh signaling was assessed on immortalized epididymal DC2 cells by western-blot, confocal imaging and 3D-reconstruction. Our results indicate that epididymal principal cells secrete Ihh and expose PC that co-localize with the conventional acetylated tubulin/Arl13b ciliary markers, as well as with GLI3 Hh signaling factor. Gene expression microarray profiling indicated that the expression of 43 and 248 genes was respectively and significantly modified following pharmacological treatment of DC2 cells with the Hh agonist SAG (250 nM) or the Hh antagonist cyclopamine (20 µM) compared with the control. Among Hh target genes identified, 6.7 % presented perfect matches for GLI-transcription factor consensus sequences, and the majority belonged to interferon-dependent immune response and lipocalin 2 pathways. Finally, the contribution of epididymal PC to the transduction of canonical Hh pathway was validated by ciliobrevinD treatment, which induced a significant decrease of PC length and the expressional reduction of Hh signalling targets. Conclusions. All together our data indicate that PC from epithelial principal cells regulate gene expression profile through a possible autocrine Hh signaling. This provides new hypotheses regarding the potential contribution of PC and Hh signaling in intercellular cross-talk and immunological regulation of the epididymis.
Project description:This study aimed to perform transcriptome profiling of Nfic-/- and corresponding control tooth germ at root initiation stage to identify differentially expressed for key regulators of root development. Coordination between the Hertwig’s Epithelial Root Sheath (HERS) and apical papilla (AP) is crucial for proper root development process. The Hedgehog (Hh) signaling pathway and Nfic are both involved in tooth root development.