scholarly journals Sonic hedgehog negatively regulates pre-TCR–induced differentiation by a Gli2-dependent mechanism

Blood ◽  
2009 ◽  
Vol 113 (21) ◽  
pp. 5144-5156 ◽  
Author(s):  
Nicola J. Rowbotham ◽  
Ariadne L. Hager-Theodorides ◽  
Anna L. Furmanski ◽  
Susan E. Ross ◽  
Susan V. Outram ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Sonic Hedgehog ◽  
Hedgehog Signaling ◽  
Negative Regulator ◽  
Double Positive ◽  
Induced Differentiation ◽  
Transgenic Expression ◽  
Tcr Signal Transduction ◽  
Hh Signaling ◽  
Dependent Mechanism

Abstract Hedgehog signaling regulates differentiation, survival, and proliferation of the earliest double-negative (DN) thymocytes, but its importance at later stages of T-cell development is controversial. Here we use loss- and gain-of-function mouse models to show that Shh, by signaling directly to the developing thymocyte, is a negative regulator of pre-TCR–induced differentiation from DN to double-positive (DP) cell. When hedgehog signaling was reduced, in the Shh−/− and Gli2−/− thymus, or by T lineage–specific transgenic expression of a transcriptional-repressor form of Gli2 (Gli2ΔC2), differentiation to DP cell after pre-TCR signal transduction was increased. In contrast, when Hh signaling was constitutively activated in thymocytes, by transgenic expression of a constitutive transcriptional-activator form of Gli2 (Gli2ΔN2), the production of DP cells was decreased. Gene expression profiling showed that physiologic Hh signaling in thymocytes maintains expression of the transcription factor FoxA2 on pre-TCR signal transduction.

scholarly journals CNPY4 inhibits the Hedgehog pathway by modulating membrane sterol lipids

2021 ◽  
Author(s):  
Megan Lo ◽  
Amnon Sharir ◽  
Michael D Paul ◽  
Hayarpi Torosyan ◽  
Christopher Agnew ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Primary Cilia ◽  
Molecular Mechanisms ◽  
Negative Regulator ◽  
Membrane Composition ◽  
Hh Signaling ◽  
Pathway Regulation ◽  
Patched 1 ◽  
Cancer Signal Transduction

The Hedgehog (HH) pathway is critical for development and adult tissue homeostasis. Aberrant HH signaling can cause congenital malformations, such as digit anomalies and holoprosencephaly, and other diseases, including cancer. Signal transduction is initiated by HH ligand binding to the Patched 1 (PTCH1) receptor on primary cilia, thereby releasing inhibition of Smoothened (SMO), a HH pathway activator. Although cholesterol and several oxysterol lipids, which are enriched in the ciliary membrane, play a crucial role in HH activation, the molecular mechanisms governing the regulation of these lipid molecules remain unresolved. Here, we identify Canopy 4 (CNPY4), a Saposin-like protein, as a regulator of the HH pathway that controls membrane sterol lipid levels. Cnpy4—/— embryos exhibit multiple defects consistent with HH signaling perturbations, most notably changes in digit number. Knockdown of Cnpy4 hyperactivates the HH pathway at the level of SMO in vitro, and elevates membrane levels of accessible sterol lipids such as cholesterol, an endogenous ligand involved in SMO activation. Thus, our data demonstrate that CNPY4 is a negative regulator that fine-tunes the initial steps of HH signal transduction, revealing a previously undescribed facet of HH pathway regulation that operates through control of membrane composition.

scholarly journals ARL13B regulates Sonic Hedgehog signaling from outside primary cilia

2019 ◽  
Author(s):  
Eduardo D. Gigante ◽  
Megan R. Taylor ◽  
Anna A. Ivanova ◽  
Richard A. Kahn ◽  
Tamara Caspary
Keyword(s):  
Signal Transduction ◽  
Sonic Hedgehog ◽  
Protein Trafficking ◽  
Hedgehog Signaling ◽  
Primary Cilia ◽  
Complete Loss ◽  
Wild Type ◽  
Sonic Hedgehog Signaling ◽  
Biochemical Function

AbstractARL13B is a regulatory GTPase highly enriched in cilia. Complete loss of Arl13b disrupts cilia architecture, protein trafficking and Sonic hedgehog signaling. To determine whether ARL13B is required within cilia, we knocked in a cilia-excluded variant of ARL13B (V358A) and showed it retains all known biochemical function. We found that ARL13BV358A protein was expressed but could not be detected in cilia, even when retrograde ciliary transport was blocked. We showed Arl13bV358A/V358A mice are viable and fertile with normal Shh signal transduction. However, in contrast to wild type cilia, Arl13bV358A/V358A cells displayed short cilia and lacked ciliary ARL3 and INPP5E. These data indicate that ARL13B’s role within cilia can be uncoupled from its function outside of cilia. Furthermore, these data imply that the cilia defects upon complete absence of ARL13B do not underlie the alterations in Shh transduction, which is unexpected given the requirement of cilia for Shh transduction.

scholarly journals ARL13B regulates Sonic hedgehog signaling from outside primary cilia

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Eduardo D Gigante ◽  
Megan R Taylor ◽  
Anna A Ivanova ◽  
Richard A Kahn ◽  
Tamara Caspary
Keyword(s):  
Signal Transduction ◽  
Sonic Hedgehog ◽  
Protein Trafficking ◽  
Hedgehog Signaling ◽  
Primary Cilia ◽  
Complete Loss ◽  
Wild Type ◽  
Sonic Hedgehog Signaling ◽  
Biochemical Function

ARL13B is a regulatory GTPase highly enriched in cilia. Complete loss of Arl13b disrupts cilia architecture, protein trafficking and Sonic hedgehog signaling. To determine whether ARL13B is required within cilia, we knocked in a cilia-excluded variant of ARL13B (V358A) and showed it retains all known biochemical function. We found that ARL13BV358A protein was expressed but could not be detected in cilia, even when retrograde ciliary transport was blocked. We showed Arl13bV358A/V358A mice are viable and fertile with normal Shh signal transduction. However, in contrast to wild type cilia, Arl13bV358A/V358A cells displayed short cilia and lacked ciliary ARL3 and INPP5E. These data indicate that ARL13B’s role within cilia can be uncoupled from its function outside of cilia. Furthermore, these data imply that the cilia defects upon complete absence of ARL13B do not underlie the alterations in Shh transduction, which is unexpected given the requirement of cilia for Shh transduction.

scholarly journals Xpo7 negatively regulates Hedgehog signaling by exporting Gli2 from the nucleus

2020 ◽  
Author(s):  
Łukasz Markiewicz ◽  
Tomasz Uśpieński ◽  
Sylwia M. Niedziółka ◽  
Paweł Niewiadomski
Keyword(s):  
Nuclear Export ◽  
Hedgehog Signaling ◽  
Negative Regulator ◽  
Nuclear Accumulation ◽  
Gli Proteins ◽  
Protein Activator ◽  
Bidirectional Transport ◽  
Hh Signaling ◽  
Nuclear Shuttling ◽  
Nuclear Export Receptor

AbstractDynamic bidirectional transport between the nucleus and the cytoplasm is critical for the regulation of many transcription factors, whose levels inside the nucleus must be tightly controlled. Efficient shuttling across the nuclear membrane is especially crucial with regard to the Hedgehog (Hh) pathway, where the transcriptional signal depends on the fine balance between the amounts of Gli protein activator and repressor forms in the nucleus. The nuclear export machinery prevents the unchecked nuclear accumulation of Gli proteins, but the mechanistic insight into this process is limited. We show that the atypical exportin Xpo7 functions as a major nuclear export receptor that actively excludes Gli2 from the nucleus and controls the outcome of Hh signaling. We show that Xpo7 interacts with several domains of Gli2 and that this interaction is dependent on SuFu, a key negative regulator of Hh signaling. Our data pave the way for a more complete understanding of the nuclear shuttling of Gli proteins and the regulation of their transcriptional activity.

scholarly journals Repurposing Niclosamide for Targeting Pancreatic Cancer by Inhibiting Hh/Gli Non-Canonical Axis of Gsk3β

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3105
Author(s):  
Jyoti B. Kaushal ◽  
Rakesh Bhatia ◽  
Ranjana K. Kanchan ◽  
Pratima Raut ◽  
Surya Mallapragada ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cell Death ◽  
Therapeutic Efficacy ◽  
Hedgehog Signaling ◽  
Negative Regulator ◽  
Phase Cell ◽  
Cycle Arrest ◽  
Hh Signaling ◽  
And Migration

Niclosamide (Nic), an FDA-approved anthelmintic drug, is reported to have anti-cancer efficacy and is being assessed in clinical trials for various solid tumors. Based on its ability to target multiple signaling pathways, in the present study, we evaluated the therapeutic efficacy of Nic on pancreatic cancer (PC) in vitro. We observed an anti-cancerous effect of this drug as shown by the G0/G1 phase cell cycle arrest, inhibition of PC cell viability, colony formation, and migration. Our results revealed the involvement of mitochondrial stress and mTORC1-dependent autophagy as the predominant players of Nic-induced PC cell death. Significant reduction of Nic-induced reactive oxygen species (ROS) and cell death in the presence of a selective autophagy inhibitor spautin-1 demonstrated autophagy as a major contributor to Nic-mediated cell death. Mechanistically, Nic inhibited the interaction between BCL2 and Beclin-1 that supported the crosstalk of autophagy and apoptosis. Further, Nic treatment resulted in Gsk3β inactivation by phosphorylating its Ser-9 residue leading to upregulation of Sufu and Gli3, thereby negatively impacting hedgehog signaling and cell survival. Nic induced autophagic cell death, and p-Gsk3b mediated Sufu/Gli3 cascade was further confirmed by Gsk3β activator, LY-294002, by rescuing inactivation of Hh signaling upon Nic treatment. These results suggested the involvement of a non-canonical mechanism of Hh signaling, where p-Gsk3β acts as a negative regulator of Hh/Gli1 cascade and a positive regulator of autophagy-mediated cell death. Overall, this study established the therapeutic efficacy of Nic for PC by targeting p-Gsk3β mediated non-canonical Hh signaling and promoting mTORC1-dependent autophagy and cell death.

scholarly journals Native V. Californicum Alkaloid Combinations Induce Differential Inhibition of Sonic Hedgehog Signaling

2018 ◽  
Author(s):  
Matthew W. Turner ◽  
Roberto Cruz ◽  
Jordan Elwell ◽  
John French ◽  
Jared Mattos ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Sonic Hedgehog ◽  
Hedgehog Signaling ◽  
Plant Part ◽  
Differential Inhibition ◽  
Sonic Hedgehog Signaling ◽  
Alkaloid Composition ◽  
Hh Signaling ◽  
Inhibitory Potential ◽  
Pathway Inhibition

Veratrum californicum is a rich source of steroidal alkaloids such as cyclopamine, a known inhibitor of the Hedgehog (Hh) signaling pathway. Here we provide a detailed analysis of the alkaloid composition of V. californicum by plant part through quantitative analysis of cyclopamine, veratramine, muldamine and isorubijervine in the leaf, stem and root/rhizome of the plant. To determine if additional alkaloids in the extracts contribute to Hh signaling inhibition, we replicated the concentrations of these alkaloids observed in extracts using commercially available standards and compared the inhibitory potential of the extracts to alkaloid standard mixtures using Shh-Light II cells. Alkaloid combinations enhanced Hh signaling pathway antagonism compared to cyclopamine alone, and significant differences were observed in the Hh pathway inhibition between the stem and root/rhizome extracts and their corresponding alkaloid standard mixtures, indicating that additional alkaloids present in these extracts contribute to Hh signaling inhibition.

scholarly journals Mice Deficient in the Fused Homolog Do Not Exhibit Phenotypes Indicative of Perturbed Hedgehog Signaling during Embryonic Development

2005 ◽  
Vol 25 (16) ◽  
pp. 7042-7053 ◽  
Author(s):  
Miao-Hsueh Chen ◽  
Nan Gao ◽  
Takatoshi Kawakami ◽  
Pao-Tien Chuang
Keyword(s):  
Signal Transduction ◽  
Embryonic Development ◽  
Hedgehog Signaling ◽  
Gene Activation ◽  
Genetic Studies ◽  
Suppressor Of Fused ◽  
Gli Transcription Factors ◽  
Processing Activity ◽  
Hh Signaling ◽  
Deficient Mice

ABSTRACT Hedgehog (Hh) signaling plays a major role in multiple aspects of embryonic development. To understand how a single Hh signal is capable of generating distinct readouts in Hh-responsive cells requires elucidation of the signal transduction cascade at the molecular level. Key components that mediate Hh signal transduction downstream of the receptor include Fused (Fu), Suppressor of fused (Sufu), and Costal-2 (Cos2) or the vertebrate homologs Kif27/Kif7. Studies with both invertebrates and vertebrates have led to a model in which a protein complex composed of Fu, Sufu, and Cos2 controls the processing, activity, and subcellular distribution of the Ci/Gli transcription factors responsible for Hh target gene activation. These converging results obtained with different species reaffirm the prevailing view of pathway conservation during evolution. Genetic studies of Fu, Sufu, and Kif27/Kif7 in mice are required to provide further verification of Hh pathway conservation. To this end, we generated a gene-targeted allele of Fu in mice. Surprisingly, our analysis indicates that Fu-deficient mice do not exhibit any embryonic phenotypes indicative of perturbed Hh signaling. This could be due to either functional redundancy or Hh pathway divergence and clearly indicates greater complexity of Hh signaling in vertebrates.

scholarly journals Heterotrimeric Gi Proteins Link Hedgehog Signaling to Activation of Rho Small GTPases to Promote Fibroblast Migration

2011 ◽  
Vol 286 (22) ◽  
pp. 19589-19596 ◽  
Author(s):  
Ariel H. Polizio ◽  
Pilar Chinchilla ◽  
Xiaole Chen ◽  
Sangbumn Kim ◽  
David R. Manning ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Rho Gtpases ◽  
Hedgehog Signaling ◽  
Mechanistic Model ◽  
Small Gtpases ◽  
Fibroblast Migration ◽  
Absolute Requirement ◽  
Small Rho Gtpases ◽  
Dependent Mechanism

Evidence supporting the functionality of Smoothened (SMO), an essential transducer in most pathways engaged by Hedgehog (Hh), as a Gi-coupled receptor contrasts with the lack of an apparently consistent requirement for Gi in Hh signal transduction. In the present study, we sought to evaluate the role of SMO-Gi coupling in fibroblast migration induced by Sonic Hedgehog (Shh). Our results demonstrate an absolute requirement for Gi in Shh-induced fibroblast migration. We found that Shh acutely stimulates the small Rho GTPases Rac1 and RhoA via SMO through a Gi protein- and PI3K-dependent mechanism, and that these are required for cell migration. These responses were independent of transcription by Gli and of the C-terminal domain of SMO, as we show using a combination of molecular and genetic tools. Our findings provide a mechanistic model for fibroblast migration in response to Shh and underscore the role of SMO-Gi coupling in non-canonical Hh signaling.

Hedgehog signaling and the axial patterning of Drosophila wings

2000 ◽  
Vol 78 (5) ◽  
pp. 585-591 ◽  
Author(s):  
William J Brook
Keyword(s):  
Signal Transduction ◽  
Cell Fate ◽  
Limb Development ◽  
Hedgehog Signaling ◽  
Post Translational Modification ◽  
Cubitus Interruptus ◽  
Axial Patterning ◽  
Correct Location ◽  
Hh Signaling ◽  
Anterior Posterior

Growth and cell fate in the anterior-posterior (A/P) axis of the developing wing of Drosophila melanogaster are controlled by a stripe of cells bisecting the axis called the A/P organizer. Hedgehog (Hh) signaling from posterior to anterior cells induces the organizer. Several Hh-responsive genes expressed by cells of the organizer mediate its patterning activity. The Hh-signaling pathway controls the post-translational modification of the transcription factor Cubitus-interruptus (Ci) and the resulting local activation of Ci is required for the correct location of the A/P organizer.Key words: Hedgehog, morphogen, Drosophila, limb development, signal transduction.

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