Sonic Hedgehog Activates Phospholipase A2 to Enhance Smoothened Ciliary Translocation

Arensdorf, Angela M.; Dillard, Miriam E.; Menke, Jacob M.; Frank, Matthew W.; Rock, Charles O.; Ogden, Stacey K.

doi:10.1016/j.celrep.2017.05.033

Cited by 27 publications

(47 citation statements)

References 55 publications

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“…Cell viability was then measured with the CCK8 assay. The in vitro experiments were conducted using the following four groups: (a) NC group, LX2 cells without any treatment; (b‐d) L, M and H groups, respectively, LX2 cells were treated with 60, 80 and 100 μM PB2, respectively; (e) cyclopamine group, LX2 cells were treated with 10 μM cyclopamine; and (f) PB2 (M) + SAG group, LX2 cells were treated with 100 nM SAG . All of the experiments were performed in triplicate.…”

Section: Methodsmentioning

confidence: 99%

Procyanidin B2 inhibits the activation of hepatic stellate cells and angiogenesis via the Hedgehog pathway during liver fibrosis

Jiao

Wang

Liu

et al. 2019

J Cellular Molecular Medi

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Background Liver fibrosis is a wound‐healing process of liver featured by the over‐deposition of extracellular matrix (ECM) and angiogenesis. However, the effective treatment is lacking. Procyanidin B2 (PB2) is a flavonoid extract abundant in grape seeds with anti‐oxidant, anti‐inflammatory and anti‐cancer properties. The present study aimed to determine effects of PB2 on liver fibrosis. Method The CCl4‐induced mouse liver fibrosis model and a human hepatic stellate cell (HSC) line (LX2 cells) were used to study the activation, ECM production and angiogenesis of HSCs through Western blotting analysis, immunohistochemistry, immunofluorescence staining, flow cytometry and tubulogenesis assay. A Hedgehog (Hh) pathway inhibitor (cyclopamine) and Smoothened agonist (SAG) were used to investigate the role of PB2 on Hh pathway. Results The results showed that PB2 could inhibit the proliferation and induce apoptosis of HSCs. PB2 could also down‐regulate the expressions of VEGF‐A, HIF‐1α, α‐SMA, Col‐1 and TGF‐β1 of HSCs in vivo and in vitro. The application of SAG and cyclopamine proved that PB2 targets on Hh pathway. Conclusions PB2 inhibited the Hh pathway to suppress the activation, ECM production and angiogenesis of HSCs, therefore reverses the progression of liver fibrosis in vivo and in vitro.

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Section: Methodsmentioning

confidence: 99%

Procyanidin B2 inhibits the activation of hepatic stellate cells and angiogenesis via the Hedgehog pathway during liver fibrosis

Jiao

Wang

Liu

et al. 2019

J Cellular Molecular Medi

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“…Gαi involvement is further supported by the observation that metabolism of arachidonic acid through the 5-lipoxygenase pathway contributes to fibroblast chemotaxis [ 44 ]. We recently demonstrated that Smo signaling through Gαiβγ activates the lipid remodeling enzyme cPLA2α to produce arachidonic acid [ 18 ], providing a mechanism by which the free fatty acid would be made available for lipoxygenase activity.…”

Section: Cytoskeletal Dynamics Cellular Migration and Axon Guidamentioning

confidence: 99%

“…However, increasing cAMP levels in pre-adipocytes in vitro can rescue adipocyte differentiation in the presence of excessive Shh signaling [ 70 , 72 ], raising the possibility that a Smo-Gαi-cAMP signal axis may be capable of influencing adipocyte differentiation in coordination with canonical Smo signaling activity. The ability of the noncanonical arm to influence the canonical arm through Gαi activation is feasible; we recently reported that arachidonic acid produced in response to Smo signaling through Gαiβγ directly associates with Smo to promote its ciliary entry and enhance signaling to Gli [ 18 ]. As such, activation of the noncanonical arm may function to amplify canonical signaling in select cell types during cell fate specification and tissue morphogenesis.…”

Section: Metabolismmentioning

confidence: 99%

“…Sterols bind through a ligand binding pocket in the extracellular amino-terminal cysteine-rich domain (CRD) of Smo [ 10 , 11 , 12 , 13 ]. A second ligand binding pocket is present in the seven-transmembrane core of Smo, and has been demonstrated to bind natural and synthetic small molecules, endocannabinoids, and the free fatty acid arachidonic acid [ 14 , 15 , 16 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Contributions of Noncanonical Smoothened Signaling During Embryonic Development

Pandit

Ogden

2017

JDB

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The Sonic Hedgehog (Shh) signaling pathway is active during embryonic development in metazoans, and provides instructional cues necessary for proper tissue patterning. The pathway signal transducing component, Smoothened (Smo), is a G protein-coupled receptor (GPCR) that has been demonstrated to signal through at least two effector routes. The first is a G protein–independent canonical route that signals to Gli transcriptional effectors to establish transcriptional programs specifying cell fate during early embryonic development. The second, commonly referred to as the noncanonical Smo signal, induces rapid, transcription-independent responses that are essential for establishing and maintaining distinct cell behaviors during development. Herein, we discuss contributions of this noncanonical route during embryonic development. We also highlight important open questions regarding noncanonical Smo signal route selection during development, and consider implications of noncanonical signal corruption in disease.

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“…Das et al 2013;Touster et al 1970;Colbeau, Nachbaur, and Vignais 1971) : how can such an abundant lipid be kept away from SMO to prevent inappropriate pathway activation? Indeed, other less abundant lipids can bind and regulate SMO activity, including oxysterols, phosphoinositides, endocannabinoids and arachidonic acid derivatives (Nachtergaele et al 2012;Khaliullina et al 2015;Arensdorf et al 2017;Jiang et al 2016) . Side-chain oxysterols, synthesized through the enzymatic or non-enzymatic oxidation of cholesterol, are appealing alternatives to cholesterol because of their lower abundance, higher hydrophilicity and structural similarity to cholesterol (Corcoran and Scott 2006;Dwyer et al 2007) .…”

Section: Introductionmentioning

confidence: 99%

Sphingomyelin suppresses Hedgehog signaling by restricting cholesterol accessibility at the ciliary membrane

Kinnebrew

Iverson

Patel

et al. 2019

Preprint

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Transmission of the Hedgehog signal across the plasma membrane by Smoothened is proposed to be triggered by its direct interaction with cholesterol. But how is cholesterol, an abundant lipid, regulated tightly enough to control a signaling system that can cause birth defects and cancer? Using toxin-based sensors that distinguish between distinct pools of cholesterol, we find here that Smoothened activation and Hedgehog signaling are driven by a biochemically defined fraction of membrane cholesterol, termed accessible cholesterol. Increasing accessible cholesterol levels by depletion of sphingomyelin, which sequesters cholesterol in complexes, potentiates Hedgehog signaling. By inactivating the transporter-like protein Patched 1, Hedgehog ligands trigger an increase in cholesterol accessibility in the ciliary membrane, the subcellular location for Smoothened signaling. Thus, compartmentalization of Hedgehog signaling in the primary cilium may allow cholesterol accessibility to be used as a second messenger to mediate the communication between Patched 1 and Smoothened, without causing collateral effects on other cellular processes. We thank Kyle Travaglini and Onn Brandman for help with the MATLAB code for automated quantitation of probe fluorescence at primary cilia, Xiaohui Zha and Kevin Courtney for helpful discussions and protocols for sphingomyelin assays, and Suzanne Pfeffer for comments on the manuscript. Author contributionsRR and AR designed the project. BP analyzed the screen data, with the exception of the KEGG analysis which was performed by MK. BP and GP designed and cloned the CRISPR library focused on lipid-related genes. BP, GP and JK generated the mutant cell library and performed the HiSHH-Bottom10% screen. MK performed the LoSHH-Top5% screen. MK performed the experiments related to cholesterol genes and MK and EJI performed experiments related to sphingomyelin genes. MK, GL and KAJ performed the lipid probe staining experiments. MK and BP designed the computational pipeline for probe quantitation at primary cilia. CS and DFC contributed key conceptual and structural insights and experimental suggestions. RR and MK wrote the paper, with input from all authors.

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Sonic Hedgehog Activates Phospholipase A2 to Enhance Smoothened Ciliary Translocation

Cited by 27 publications

References 55 publications

Procyanidin B2 inhibits the activation of hepatic stellate cells and angiogenesis via the Hedgehog pathway during liver fibrosis

Procyanidin B2 inhibits the activation of hepatic stellate cells and angiogenesis via the Hedgehog pathway during liver fibrosis

Contributions of Noncanonical Smoothened Signaling During Embryonic Development

Sphingomyelin suppresses Hedgehog signaling by restricting cholesterol accessibility at the ciliary membrane

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