An essential role for the Gai2 protein in Smoothened-stimulated mammary epithelial cell proliferation
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ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Chad Shaw
PROVIDER: E-GEOD-70210 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Hedgehog (Hh) signaling is critical for organogenesis, tissue homeostasis, and stem cell maintenance. Smoothened (SMO), the primary effector of Hh signaling, is expressed ectopically in human breast cancer, as well as in other cancers. Constitutive activation of SMO in mouse mammary glands leads to paracrine stimulation of proliferation, as well as hyperplasia. In canonical signaling, SMO functions via GLI transcription factor activation. However, recent data from Drosophila and mammalian cell lines indicate that SMO can function non-canonically as a G-protein coupled receptor (GPCR) by coupling to heterotrimeric G proteins, particularly those in the pertussis toxin (PTX)-sensitive G-alpha-i (Gai) class. Whether SMO functions as a GPCR in mammalian tissues in vivo is not known. Using genetically modified mouse models, we demonstrate here that SMO-induced stimulation of proliferation is PTX sensitive, and requires Gai2, but not Gai1 or Gai3. Our findings provide evidence for a non-canonical GPCR function of activated SMO in vivo, a finding that may have clinical significance given that most SMO-targeted agents were selected based largely on their ability to block canonical GLI-mediated transcription.
2015-09-08 | GSE70210 | GEO
Project description:The Hedgehog (Hh) pathway is essential for tissue homeostasis, and misregulation of this cascade drives several cancers. To control expression of pathway target genes, the G protein-coupled receptor (GPCR) Smoothened (SMO) activates glioma-associated (GLI) transcription factors via an unknown mechanism. Here we show that, rather than conforming to traditional GPCR signaling paradigms, SMO activates GLI by binding and sequestering protein kinase A (PKA) catalytic subunits at the membrane. This sequestration, triggered by GPCR kinase 2 (GRK2)-mediated phosphorylation of SMO intracellular domains, prevents PKA from phosphorylating soluble substrates, releasing GLI from PKA-mediated inhibition. Our work provides a mechanism directly linking vertebrate Hh signal transduction at the membrane to transcription factor activation in the nucleus. In contrast to existing models, our work shows that this aspect of Hh signaling is fundamentally similar between species. The mechanism described here may apply broadly to other GPCR- and PKA-containing cascades.
2021-04-25 | PXD019346 | Pride
Project description:In order to gain a better understanding of Ihh action during embryo implantation, we constitutively activated Smo in the murine uterus using the PRcre mouse model (PRcre/+SmoM2+; SmoM2). Female SmoM2 mice were infertile. They exhibited normal serum progesterone levels and normal ovulation, but ova failed to be fertilized in vivo and the uterus failed to undergo the artificially induced decidual response. SmoM2 mice exhibited uterine hypertrophy. The endometrium had a reduced number of uterine glands and the endometrial stroma lost its normal morphologic characteristics. Microarray analysis of 3 month old SmoM2 uteri demonstrated a chondrocytic signature and confirmed that constitutive activation of SmoM2 increased extracellular matrix production. Thus, constitutive activation of Smo in the mouse uterus alters the extracellular matrix which interferes with early pregnancy. Keywords: two group comparison We constitutively activated Hh signaling in the uterus by the expression of a mutant SmoM2 allele. We crossed these mice to the PRcre mouse model to constitutively activate Smo in the murine uterus (PRcre/+SmoM2+; SmoM2). High density DNA microarray analysis was performed on 3 month old control and SmoM2 uteri.
2010-04-13 | E-GEOD-17263 | biostudies-arrayexpress
Project description:The Hedgehog (Hh) pathway is essential for organ development, homeostasis, and regeneration. Dysfunction of this cascade drives several cancers. To control expression of pathway target genes, the G protein-coupled receptor (GPCR) Smoothened (SMO) activates glioma-associated (GLI) transcription factors via an unknown mechanism. Here we show that, rather than conforming to traditional GPCR signaling paradigms, SMO activates GLI by binding and sequestering protein kinase A (PKA) catalytic subunits at the membrane. This sequestration, triggered by GPCR kinase (GRK)-mediated phosphorylation of SMO intracellular domains, prevents PKA from phosphorylating soluble substrates, releasing GLI from PKA-mediated inhibition. Our work provides a mechanism directly linking Hh signal transduction at the membrane to GLI transcription in the nucleus. This process is more fundamentally similar between species than prevailing hypotheses suggest. The mechanism described here may apply broadly to other GPCR- and PKA-containing cascades in diverse areas of biology.
2021-04-25 | PXD023893 | panorama
Project description:Recent fate mapping studies concluded that EMT is not required for metastasis of carcinomas. Here we challenge this conclusion by showing that it failed to account for possible crosstalk between EMT and non-EMT cells that promotes dissemination of non-EMT cells. In breast cancer models, EMT cells induce increased metastasis of weakly metastatic, non-EMT tumor cells in a paracrine manner in part by non-cell autonomous activation of the GLI transcription factor. Treatment with GANT61, a GLI1/2 inhibitor, but not with IPI-926, a Smoothened inhibitor, blocks this effect, and inhibits growth in PDX models. In human breast tumors, the EMT-TFs strongly correlate with activated Hedgehog/GLI signaling, but not with the Hh ligands. Our findings indicate that EMT contributes to metastasis in part via non-cell autonomous effects that activate the Hh pathway. While all Hh inhibitors may act against tumors with canonical Hh/GLI signaling, only GLI inhibitors would act against EMT-induced GLI activation. In recent years, immunohistochemical analyses and multiplex high-throughput single cell sequencing of human tumor cells have shown that tumors are composed of diverse cell subpopulations containing different driver mutations, gene and protein expression profiles, growth rates, and responses to chemotherapeutics. Such heterogeneity is exacerbated by cellular plasticity, where some cells may undergo oncogenic epithelial-to-mesenchymal transition (EMT), resulting in loss of cell-cell adhesion and polarity, reduced epithelial and elevated mesenchymal protein expression, increased migration and invasion, and enhanced dissemination from the primary tumor. Because metastases in patients appear epithelial, the reverse process, mesenchymal-to-epithelial transition (MET), may occur to allow tumor cell colonization in secondary metastatic sites, establishing cellular plasticity as an important aspect of tumor progression. However, the role of EMT in carcinoma metastasis is controversial. Recent lineage tracing studies argue against the requirement of EMT for metastasis, as reporter-tagged cells that underwent a previous EMT were not found at the secondary site. However, these studies did not address the potential cooperation between EMT and non-EMT cells during the metastatic process, as EMT cancer cells may enable non-EMT cells to gain access to the secondary site, leading to macrometastatic growth. Thus, metastasis can be influenced by intratumoral heterogeneity: where a small proportion of primary tumor cells that have undergone an EMT may influence neighboring, non-EMT tumor cells. Twist1, Snail1, and Six1 are EMT-inducing transcription factors (EMT-TFs) that have all been associated with breast cancer metastasis. All three EMT-TFs regulate critical developmental processes such as cell survival, migration and invasion; in part by influencing EMT. In addition, they are downregulated post-embryogenesis, but re-expressed in various cancers where they cell autonomously induce EMT, resulting in increased percentages of tumor initiating cells (TICs) and enhanced metastasis. In carcinomas, Twist1 and Snail1 transcriptionally repress E-Cadherin (E- Cad) and upregulate mesenchymal genes. Similarly, Six1 overexpression induces EMT by regulating E-Cad localization and altering other EMT markers. During development and cancer, EMT-TFs act in concert with several signaling networks including TGFβ, Wnt, and Hedghog (Hh). The Hedgehog (Hh) signaling pathway is a prominent regulator of embryonic development, where Hh ligands function as morphogens to control numerous developmental processes. Interestingly, in Drosophila eye development, hh is a direct target of sine oculis (the homolog of Six1) and Six1 regulates Hh/GLI signaling during lung development and in fibroblasts. Additionally, Twist1 and Hh/GLI signaling are intimately linked during development, and recently Twist1 and Snail1 were associated with the Hh pathway in TICs. In mammals, canonical activation of Hh/GLI signaling involves binding of one the Hh ligands such as(either, Desert (DHH), Indian (IHH), or Sonic Hedgehog (SHH) to Patched-1 (PTCH1) or Patched-2 (PTCH2) receptors, relieving the inhibitory activity of PTCH on Smoothened (SMO). When inhibition is relieved, levels of the transcriptional activator forms of one or more GLI transcription factors (GLI1, 2, or 3) increase in the nucleus, resulting in activation of Hh target genes 12. Non-canonical activation of the GLI TFs can occur in a Hh- or SMO-independent manner via secreted factors like TGF-β19. Importantly, autocrine and paracrine Hh-mediated crosstalk between tumor cells and the tumor microenvironment 20 results in increased proliferation, stem cell self-renewal and metastasis in various cancers 21. In basal cell carcinoma (BCC) and medulloblastoma, activated Hh signaling is often due to mutations in pathway components such as PTCH and SMO, while in other tumor types including breast, mutations are not observed at high frequency. Instead there is evidence for Hh ligand-dependent pathway hyperactivity. Because numerous studies link Hh signaling to progression in multiple tumor types, derivatives of cyclopamine (e.g. GDC-0449 and IPI926), a naturally occurring plant-derived steroidal alkaloid which targets SMO, are in clinical trials for select patients with BCC and medulloblastoma with promising efficacy. However, these inhibitors have not shown promise in breast cancer despite evidence for activation of this pathway. Herein, we demonstrate that EMT-TFs Twist1, Snail1 and Six1 influence neighboring carcinoma cells in a non-cell autonomous manner, by increasing EMT features and aggressive properties of cells not expressing these TFs. Six1 is a key mediator of the non-cell autonomous effects downstream of Twist1 and Snail1, and can induce metastasis of non-Six1, non-EMT cells. All three EMT-TFs function non-cell autonomously by activation of GLI-mediated transcription in non-EMT cells, but employ different mechanisms of pathway activation, some of which are Hh ligand and SMO-independent. We find that pharmacological inhibition of GLI, but not SMO, in the non-EMT cells efficiently inhibits the non-cell autonomous phenotypes imparted by all three EMT-TFs. Importantly, we demonstrate that in selected patient derived breast cancer xenograft (PDX) models endogenously expressing high levels of these EMT-TFs (but not Hh ligands), GANT61 (a GLI1/2 inhibitor) inhibits tumor growth whereas IPI926 (a SMO inhibitor) did not. Our data suggest that upstream SMO inhibitors may not prove efficacious in tumors where a proportion of cells activate GLI-TF via EMT-TFs, and instead argue that inhibitors directly targeting GLI may be more effective.
2017-04-13 | GSE97726 | GEO
Project description:T-cell acute lymphoblastic leukemia (T-ALL) is a highly malignant pediatric leukemia, where few therapeutic options are available for patients which relapse. The evolutionarily conserved Hedgehog (Hh) pathway plays a crucial role in patterning and organogenesis during early development, in adult tissue maintenance and repairing functions. Once Hh ligands bind to PTCH1/2 on target cells, the inhibition of Patched proteins for Smo is relieved. Smo translocates to the primary cilium and leads to the breakdown of a protein complex formed by Suppressor of Fused (SUFU) and GLI proteins. GLI transcription factors (GLI1-3) are released and translocate to the nucleus, initiating transcription of Hh target genes. GLI2 and GLI3 have transcriptional activation and repression properties, while GLI1 is a strong positive regulator of Hh transcriptional targets. In T-ALL rare hedgehog pathway mutations have been observed and approximately 20% of T-ALL cases present with ectopic expression of Hh pathway ligands and GLI1. However, the function of Hh signaling and in particular GLI transcription factors in T-ALL initiation and/or tumor progression is not well-known. RNA sequencing was performed in the CUTLL1 T-ALL cell line after knocking out GLI1 gene using CRISPR/Cas9 system.
2020-07-03 | GSE153718 | GEO
Project description:In the bone marrow B cell development occurs in initimate and essential association with stromal cells. Known effects of stromal cells on B cell development have been shown to be mediated through direct contact and by soluble factors produced by stromal cells. Our findings suggest that cell-nonautonomous Hh signaling may play an important role in B cell lymphopoiesis. We therefore interrogated OP9 stromal cells for Hh-dependent transcripts that may confer B lymphopoietic identity. We generated OP9 stromal cells deficient in Hh signaling through targeting the non-redundant, pathway-obligate GPCR Smoothened. OP9 cells were transduced with RNAi pLKO.1-Puro lentiviral particles expressing a scrambled control shRNA (NT) or shRNA targeting Smoothened (Smo-kd). RNA from stable NT and Smo-kd OP9 cells were isolated in triplicate and global changes in transcripts were analyzed using the Affymetrix Mouse Exon 1.0 ST gene chip.
2012-07-11 | E-GEOD-34421 | biostudies-arrayexpress
Project description:Sonic hedgehog (Shh) signals via Gli transcription factors to direct digit number and identity in the vertebrate limb. We have characterized the Gli-dependent cis-regulatory network through a combination of whole genome ChIP-on-chip and transcriptional profiling of the developing mouse limb. In this dataset, we include the expression data obtained from dissected mouse forelimbs using a variety of gain- and loss-of-function hedgehog pathway mutants, as well as limbs dissected into responsive (posterior 2/3ds) and non-responsive (anterior 1/3d) Hh tissues. These data are used to obtain 753 genes that are differentially expressed in response to Shh signaling. Keywords: Comparison of genetic samples 28 Total samples were analyzed. We generated the following pairwise comparisons using PowerExpress: Shh<WT; SmoM2>WT; Gli3<WT; Gli3>WT; Ant<Post; Ant>Post. Genes with an FDRM-bM-^IM-$10% and a fold-change M-bM-^IM-%2 were selected. We did not generate pairwise comparisons for a certain combinations with SmoGli3 and Gli3 mutants because data from these arrays contained significant variability. To identify additional genes that were Shh-responsive, we performed the following multiple sample comparisons using an FDRM-bM-^IM-$10% and a posterior probability cutoff of M-bM-^IM-$25%: 1.) Ant<Post and Shh<WT<SmoM2, 2.) Ant<Post and Shh<WT<SmoM2 and Gli3>SmoGli3, 3.) Ant<Post and Shh<WT<SmoM2 and WT>SmoGli3
2008-09-14 | E-GEOD-11063 | biostudies-arrayexpress
Project description:Excessive Hedgehog (Hh) signaling activity contributes to fibrosis in multiple organs, however, its role in pancreatic stellate cell (PSC) activation and fibrosis development during chronic pancreatitis (CP) remains unclear. We demonstrate that GLI2 is upregulated in activated PSCs from CP patients and animal models. Specific deletion of Gli2, but not Smo, significantly alleviated fibrosis in CP models, indicating that CP is driven by non-canonical Hh signaling. Experiments on culture-activated primary PSCs reveal early nuclear translocation and increased GLI2 expression promptly after in vitro culture, with GLI2 being essential for PSC activation. SMO inhibition only reduces GLI2 activation in the short term, while activation of GLI2 by TGF-β/SMAD3 signaling explains the SMO-independent mechanisms leading to Hh activation in PSCs. Altogether, our data demonstrate the activation of the non-canonical Hh pathway in PSCs and indicate that GLI2 represents a promising therapeutic target for CP.
2024-11-13 | GSE281427 | GEO
Project description:We disrupted the spatial Hh activation gradient in murine lung by inducing the constitutively active form of the Hh effector, Smo (SmoM2), throughout the entire GLI2+ stroma and performed RNA-seq on the bulk GLI2+ population. Whole adult murine lung tissue was dissociated to single cells and subjected to fluorescence activated cell sorting (FACS) to select all live GLi2+ cells. The bulk RNA-sequencing library was then subsequently generated. Cells were sequenced at a depth of average of 45 million reads/sample. The results reveal that expansion of Hh activation in the GLI2+ domain in the murine lung resulted in upregulation of genes that are expressed in the proximal stroma fibroblasts. Conversely, Hh activation downregulated genes enriched in the distal stroma as well as mesothelial cells.
2018-08-08 | GSE102589 | GEO