Browse
Submit Data
Databases
API
Help

Dataset Information

24 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A Smoothened-Evc2 complex transduces the Hedgehog signal at primary cilia.

ABSTRACT: Vertebrate Hedgehog (Hh) signaling is initiated at primary cilia by the ligand-triggered accumulation of Smoothened (Smo) in the ciliary membrane. The underlying biochemical mechanisms remain unknown. We find that Hh agonists promote the association between Smo and Evc2, a ciliary protein that is defective in two human ciliopathies. The formation of the Smo-Evc2 complex is under strict spatial control, being restricted to a distinct ciliary compartment, the EvC zone. Mutant Evc2 proteins that localize in cilia but are displaced from the EvC zone are dominant inhibitors of Hh signaling. Disabling Evc2 function blocks Hh signaling at a specific step between Smo and the downstream regulators protein kinase A and Suppressor of Fused, preventing activation of the Gli transcription factors. Our data suggest that the Smo-Evc2 signaling complex at the EvC zone is required for Hh signal transmission and elucidate the molecular basis of two human ciliopathies.

SUBMITTER: Dorn KV

PROVIDER: S-EPMC3586260 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

A Smoothened-Evc2 complex transduces the Hedgehog signal at primary cilia.

Dorn Karolin V KV Hughes Casey E CE Rohatgi Rajat R

Developmental cell 20120913 4

Vertebrate Hedgehog (Hh) signaling is initiated at primary cilia by the ligand-triggered accumulation of Smoothened (Smo) in the ciliary membrane. The underlying biochemical mechanisms remain unknown. We find that Hh agonists promote the association between Smo and Evc2, a ciliary protein that is defective in two human ciliopathies. The formation of the Smo-Evc2 complex is under strict spatial control, being restricted to a distinct ciliary compartment, the EvC zone. Mutant Evc2 proteins that lo ...[more]

PMID: 22981989

Similar Datasets

Smoothened transduces Hedgehog signal by forming a complex with Evc/Evc2.

Project description:Hedgehog (Hh) signaling plays pivotal roles in embryonic development and adult tissue homeostasis in species ranging from Drosophila to mammals. The Hh signal is transduced by Smoothened (Smo), a seven-transmembrane protein related to G protein coupled receptors. Despite a conserved mechanism by which Hh activates Smo in Drosophila and mammals, how mammalian Hh signal is transduced from Smo to the Gli transcription factors is poorly understood. Here, we provide evidence that two ciliary proteins, Evc and Evc2, the products of human disease genes responsible for the Ellis-van Creveld syndrome, act downstream of Smo to transduce the Hh signal. We found that loss of Evc/Evc2 does not affect Sonic Hedgehog-induced Smo phosphorylation and ciliary localization but impedes Hh pathway activation mediated by constitutively active forms of Smo. Evc/Evc2 are dispensable for the constitutive Gli activity in Sufu(-/-) cells, suggesting that Evc/Evc2 act upstream of Sufu to promote Gli activation. Furthermore, we demonstrated that Hh stimulates binding of Evc/Evc2 to Smo depending on phosphorylation of the Smo C-terminal intracellular tail and that the binding is abolished in Kif3a(-/-) cilium-deficient cells. We propose that Hh activates Smo by inducing its phosphorylation, which recruits Evc/Evc2 to activate Gli proteins by antagonizing Sufu in the primary cilia.

| S-EPMC3494391 | biostudies-literature

Sequential phosphorylation of smoothened transduces graded hedgehog signaling.

Project description:The correct interpretation of a gradient of the morphogen Hedgehog (Hh) during development requires phosphorylation of the Hh signaling activator Smoothened (Smo); however, the molecular mechanism by which Smo transduces graded Hh signaling is not well understood. We show that regulation of the phosphorylation status of Smo by distinct phosphatases at specific phosphorylated residues creates differential thresholds of Hh signaling. Phosphorylation of Smo was initiated by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (PKA) and further enhanced by casein kinase I (CKI). We found that protein phosphatase 1 (PP1) directly dephosphorylated PKA-phosphorylated Smo to reduce signaling mediated by intermediate concentrations of Hh, whereas PP2A specifically dephosphorylated PKA-primed, CKI-phosphorylated Smo to restrict signaling by high concentrations of Hh. We also established a functional link between sequentially phosphorylated Smo species and graded Hh activity. Thus, we propose a sequential phosphorylation model in which precise interpretation of morphogen concentration can be achieved upon versatile phosphatase-mediated regulation of the phosphorylation status of an essential activator in developmental signaling.

| S-EPMC3526344 | biostudies-literature

EFCAB7 and IQCE regulate hedgehog signaling by tethering the EVC-EVC2 complex to the base of primary cilia.

Project description:The Hedgehog (Hh) pathway depends on primary cilia in vertebrates, but the signaling machinery within cilia remains incompletely defined. We report the identification of a complex between two ciliary proteins, EFCAB7 and IQCE, which positively regulates the Hh pathway. The EFCAB7-IQCE module anchors the EVC-EVC2 complex in a signaling microdomain at the base of cilia. EVC and EVC2 genes are mutated in Ellis van Creveld and Weyers syndromes, characterized by impaired Hh signaling in skeletal, cardiac, and orofacial tissues. EFCAB7 binds to a C-terminal disordered region in EVC2 that is deleted in Weyers patients. EFCAB7 depletion mimics the Weyers cellular phenotype-the mislocalization of EVC-EVC2 within cilia and impaired activation of the transcription factor GLI2. Evolutionary analysis suggests that emergence of these complexes might have been important for adaptation of an ancient organelle, the cilium, for an animal-specific signaling network.

| S-EPMC4027042 | biostudies-literature

Interaction of smoothened with integrin-linked kinase in primary cilia mediates Hedgehog signalling.

Project description:Here we report that ILK localizes in the mouse primary cilium, a sensory organelle required for signalling by the Hedgehog (Hh) pathway. Genetic or pharmacological inhibition of ILK blocks ciliary accumulation of the Hh pathway effector smoothened (Smo) and suppresses the induction of Gli transcription factor mRNAs by SHh. Conditional deletion of ILK or Smo also inhibits SHh-driven activation of Gli2 in the embryonic mouse cerebellum. ILK regulation of Hh signalling probably requires the physical interaction of ILK and Smo in the cilium, and we also show selective cilia-associated interaction of ILK with ?-arrestin, a known mediator of Smo-dependent signalling.

| S-EPMC3790053 | biostudies-literature

Smoothened Transduces Hedgehog Signals via Activity-Dependent Sequestration of PKA Subunits

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

Single-molecule imaging of Hedgehog pathway protein Smoothened in primary cilia reveals binding events regulated by Patched1.

Project description:Accumulation of the signaling protein Smoothened (Smo) in the membrane of primary cilia is an essential step in Hedgehog (Hh) signal transduction, yet the molecular mechanisms of Smo movement and localization are poorly understood. Using ultrasensitive single-molecule tracking with high spatial/temporal precision (30 nm/10 ms), we discovered that binding events disrupt the primarily diffusive movement of Smo in cilia at an array of sites near the base. The affinity of Smo for these binding sites was modulated by the Hh pathway activation state. Activation, by either a ligand or genetic loss of the negatively acting Hh receptor Patched-1 (Ptch), reduced the affinity and frequency of Smo binding at the base. Our findings quantify activation-dependent changes in Smo dynamics in cilia and highlight a previously unknown step in Hh pathway activation.

| S-EPMC4500289 | biostudies-literature

A PKA inhibitor motif within SMOOTHENED controls Hedgehog signal transduction.

Project description:The Hedgehog (Hh) cascade is central to development, tissue homeostasis and cancer. A pivotal step in Hh signal transduction is the activation of glioma-associated (GLI) transcription factors by the atypical G protein-coupled receptor (GPCR) SMOOTHENED (SMO). How SMO activates GLI remains unclear. Here we show that SMO uses a decoy substrate sequence to physically block the active site of the cAMP-dependent protein kinase (PKA) catalytic subunit (PKA-C) and extinguish its enzymatic activity. As a result, GLI is released from phosphorylation-induced inhibition. Using a combination of in vitro, cellular and organismal models, we demonstrate that interfering with SMO-PKA pseudosubstrate interactions prevents Hh signal transduction. The mechanism uncovered echoes one used by the Wnt cascade, revealing an unexpected similarity in how these two essential developmental and cancer pathways signal intracellularly. More broadly, our findings define a mode of GPCR-PKA communication that may be harnessed by a range of membrane receptors and kinases.

| S-EPMC9696579 | biostudies-literature

Multiple ligand binding sites regulate the Hedgehog signal transducer Smoothened in vertebrates.

Project description:The Hedgehog (Hh) pathway plays a central role in the development of multicellular organisms, guiding cell differentiation, proliferation and survival. While many components of the vertebrate pathway were discovered two decades ago, the mechanism by which the Hh signal is transmitted across the plasma membrane remains mysterious. This fundamental task in signalling is carried out by Smoothened (SMO), a human oncoprotein and validated cancer drug target that is a member of the G-protein coupled receptor protein family. Recent structural and functional studies have advanced our mechanistic understanding of SMO activation, revealing its unique regulation by two separable but allosterically-linked ligand-binding sites. Unexpectedly, these studies have nominated cellular cholesterol as having an instructive role in SMO signalling.

| S-EPMC5949240 | biostudies-literature

Primary cilia attenuate hedgehog signalling in neoplastic chondrocytes.

Project description:Primary cilia can act as either a negative or positive regulator of the hedgehog (Hh) signaling pathway. Many cartilage tumors are characterized by abnormal activation of the Hh pathway. Here, we report that the presence of primary cilia occurs at a low frequency (12.4%) in neoplastic chondrocytes from malignant human chondrosarcomas, compared with chondrocytes from normal articular cartilage (67.7%). To determine the function of primary cilia in cartilaginous neoplasia, we studied benign cartilage tumors that are formed in mice by chondrocyte-specific overexpression of Gli2, a downstream transcriptional activator of the Hh pathway. Col2A1-Gli2 mice were crossed with Ift88+/- mice, which display a partial loss of ciliogenesis. Surprisingly, cartilage tumors developed in Ift88+/- mice that were phenotypically similar to those that arise in Col2A1-Gli2 mice. Further activation of the Hh pathway was observed in Col2A1-Gli2; Ift88+/- mice compared with either Col2A1-Gli2 or Ift88+/- mice, which was associated with an increased incidence of cartilage tumors. Chondrosarcomas were established in explant cultures, and treated with choral hydrate, which disrupts the functional primary cilia. Thus, treatment resulted in hyperactivity of the Hh signaling pathway, as well as cellular changes that could promote tumor growth. Primary cilia functions to inhibit Hh signaling in neoplastic chondrocytes. The activation of Hh signaling is sufficient to induce benign cartilage tumors without another oncogenic initiating event. Moreover, as primary cilia suppress Hh pathway activation in chondrosarcoma, cellular mechanisms inhibiting proper cilia function may be important in maintaining the neoplastic phenotype.

| S-EPMC3898120 | biostudies-literature

Primary cilia regulate Gli/Hedgehog activation in pancreas.

Project description:Previous studies have suggested that defects in pancreatic epithelium caused by activation of the Hedgehog (Hh) signaling pathway are secondary to changes in the differentiation state of the surrounding mesenchyme. However, recent results describe a role of the pathway in pancreatic epithelium, both during development and in adult tissue during neoplastic transformation. To determine the consequences of epithelial Hh activation during pancreas development, we employed a transgenic mouse model in which an activated version of GLI2, a transcriptional mediator of the pathway, is overexpressed specifically in the pancreatic epithelium. Surprisingly, efficient Hh activation was not observed in these transgenic mice, indicating the presence of physiological mechanisms within pancreas epithelium that prevent full Hh activation. Additional studies revealed that primary cilia regulate the level of Hh activation, and that ablation of these cellular organelles is sufficient to cause significant up-regulation of the Hh pathway in pancreata of mice overexpressing GLI2. As a consequence of overt Hh activation, we observe profound morphological changes in both the exocrine and endocrine pancreas. Increased Hh activity also induced the expansion of an undifferentiated cell population expressing progenitor markers. Thus, our findings suggest that Hh signaling plays a critical role in regulating pancreatic epithelial plasticity.

| S-EPMC2890485 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data