1
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Lu C, Xu Y, Chen S, Guo L, Li P, Wei X, Rong X. Mendelian randomization analysis to identify potential drug targets for osteoarthritis. PLoS One 2025; 20:e0316824. [PMID: 39932908 PMCID: PMC11813149 DOI: 10.1371/journal.pone.0316824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2024] [Accepted: 12/16/2024] [Indexed: 02/13/2025] Open
Abstract
BACKGROUND Osteoarthritis (OA) is a prevalent chronic joint disease for which there is a lack of effective treatments. In this study, we used Mendelian randomization analysis to identify circulating proteins that are causally associated with OA-related traits, providing important insights into potential drug targets for OA. METHOD Causal associations between 1553 circulating proteins and five OA-related traits were assessed in large-scale two-sample MR analyses using Wald ratio or inverse variance weighting, and the results were corrected for Bonferroni. In addition, sensitivity analyses were performed to validate the reliability of the MR results, including reverse MR analysis and Steiger filtering to ensure the causal direction between circulating proteins and OA; Bayesian co-localization and phenotypic scanning were used to eliminate confounding effects and horizontal pleiotropy. External validation was performed to exclude incidental findings using novel plasma protein quantitative trait loci. Finally, the online analysis tool Enrichr was utilized to screen drugs and molecular docking was performed to predict binding modes and energies between proteins and drugs to identify the most stable and likely binding modes and drugs. RESULT Four proteins were ultimately found to be reliably and causally associated with three OA-related features: DNAJB12 and USP8 were associated with knee OA, IL12B with spinal OA, and RGMB with thumb OA. The ORs for the above proteins were 1.51 (95% CI, 1.26-1.81), 1.72 (95% CI, 1.42-2.08), 0.87 (95% CI, 0.81-0.92), and 0.59 (95% CI, 0.47-0.75), respectively. Drug-predicting small molecules (doxazosin, XEN 103, and montelukast) that simultaneously target three proteins, DNAJB12, USP8, and IL12B, docked well. CONCLUSION Based on our comprehensive analysis, we can draw the conclusion that there is a causal relationship between the genetic levels of DNAJB12, USP8, IL12B, and RGMB and the risk of respective OA.They may be potential options for OA screening and prevention in clinical practice. They can also serve as candidate molecules for future mechanism exploration and drug target selection.
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Affiliation(s)
- Chengyang Lu
- Department of Orthopedics, Shanxi Key Laboratory of Bone and Soft Tissue Injury Repair, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Yanan Xu
- Department of Laboratory, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Shuai Chen
- Department of Orthopedics, Shanxi Key Laboratory of Bone and Soft Tissue Injury Repair, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Li Guo
- Department of Orthopedics, Shanxi Key Laboratory of Bone and Soft Tissue Injury Repair, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Pengcui Li
- Department of Orthopedics, Shanxi Key Laboratory of Bone and Soft Tissue Injury Repair, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xiaochun Wei
- Department of Orthopedics, Shanxi Key Laboratory of Bone and Soft Tissue Injury Repair, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xueqin Rong
- Department of Pain Medicine Center, The Central Hospital of Sanya, Sanya City, Hainan Province, China
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Cai J, Huang K, Li W, Wang T, Yue S, Chen Z, Xing G, Wei Q, Yao J, Cao X. Implication of GPRASP2 in the Proliferation and Hair Cell-Forming of Cochlear Supporting Cells. Cell Prolif 2024:e13792. [PMID: 39675768 DOI: 10.1111/cpr.13792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2024] [Revised: 11/24/2024] [Accepted: 11/28/2024] [Indexed: 12/17/2024] Open
Abstract
G protein-coupled receptor-associated sorting protein 2 (GPRASP2) has been identified as the causative gene for X-linked recessive syndromic hearing loss (SHL) in our previous study. However, the role of GPRASP2 in auditory function remains unclear. The present study demonstrated that Gprasp2 overexpression in mouse organoids promoted the proliferation of supporting cells (SCs), which was mainly mediated by the Hedgehog signalling pathway. Meanwhile, GPRASP2 promoted hair cell (HC) formation from SCs via β-catenin signalling. In addition, GPRASP2 deficiency resulted in increased lysosomal degradation of SMO protein, leading to decreased expression of β-catenin and the Hedgehog pathway transcription factor GLI1. In neomycin-treated mouse cochlear explant, the smoothened agonist (SAG) recured the HC loss and further facilitated AAV-ie-Gprasp2 to promote the proliferation of SCs and formation of HCs. Our results suggested that GPRASP2 could be a potential candidate for gene therapy in the regeneration of HCs.
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Affiliation(s)
- Jing Cai
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Kun Huang
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Wenrui Li
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Tianming Wang
- Central Laboratory, Translational Medicine Research Center, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, China
| | - Shen Yue
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Zhibin Chen
- Department of Otolaryngology, The First Affiliated Hospital With Nanjing Medical University, Nanjing, China
| | - Guangqian Xing
- Department of Otolaryngology, The First Affiliated Hospital With Nanjing Medical University, Nanjing, China
| | - Qinjun Wei
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China
| | - Jun Yao
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China
| | - Xin Cao
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China
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3
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Latham AP, Tempkin JOB, Otsuka S, Zhang W, Ellenberg J, Sali A. Integrative spatiotemporal modeling of biomolecular processes: application to the assembly of the Nuclear Pore Complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.06.606842. [PMID: 39149317 PMCID: PMC11326192 DOI: 10.1101/2024.08.06.606842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Dynamic processes involving biomolecules are essential for the function of the cell. Here, we introduce an integrative method for computing models of these processes based on multiple heterogeneous sources of information, including time-resolved experimental data and physical models of dynamic processes. We first compute integrative structure models at fixed time points and then optimally select and connect these snapshots into a series of trajectories that optimize the likelihood of both the snapshots and transitions between them. The method is demonstrated by application to the assembly process of the human Nuclear Pore Complex in the context of the reforming nuclear envelope during mitotic cell division, based on live-cell correlated electron tomography, bulk fluorescence correlation spectroscopy-calibrated quantitative live imaging, and a structural model of the fully-assembled Nuclear Pore Complex. Modeling of the assembly process improves the model precision over static integrative structure modeling alone. The method is applicable to a wide range of time-dependent systems in cell biology, and is available to the broader scientific community through an implementation in the open source Integrative Modeling Platform software.
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Affiliation(s)
- Andrew P Latham
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Jeremy O B Tempkin
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Shotaro Otsuka
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Wanlu Zhang
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jan Ellenberg
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94143, USA
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4
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Falsztyn IB, Taylor SM, Baugh LR. Developmental and conditional regulation of DAF-2/INSR ubiquitination in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.24.595723. [PMID: 38854056 PMCID: PMC11160630 DOI: 10.1101/2024.05.24.595723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Insulin/IGF signaling (IIS) regulates developmental and metabolic plasticity. Conditional regulation of insulin-like peptide expression and secretion promotes different phenotypes in different environments. However, IIS can also be regulated by other, less-understood mechanisms. For example, stability of the only known insulin/IGF receptor in C. elegans, DAF-2/INSR, is regulated by CHIP-dependent ubiquitination. Disruption of chn-1/CHIP reduces longevity in C. elegans by increasing DAF-2/INSR abundance and IIS activity in adults. Likewise, mutation of a ubiquitination site causes daf-2(gk390525) to display gain-of-function phenotypes in adults. However, we show that this allele displays loss-of-function phenotypes in larvae, and that its effect on IIS activity transitions from negative to positive during development. In contrast, the allele acts like a gain-of-function in larvae cultured at high temperature, inhibiting temperature-dependent dauer formation. Disruption of chn-1/CHIP causes an increase in IIS activity in starved L1 larvae, unlike daf-2(gk390525). CHN-1/CHIP ubiquitinates DAF-2/INSR at multiple sites. These results suggest that the sites that are functionally relevant to negative regulation of IIS vary in larvae and adults, at different temperatures, and in nutrient-dependent fashion, revealing additional layers of IIS regulation.
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Affiliation(s)
| | - Seth M. Taylor
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - L. Ryan Baugh
- Department of Biology, Duke University, Durham, NC 27708, USA
- Center for Genomic and Computational Biology, Duke University, Durham, NC 27708, USA
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5
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Zhang J, Liu Y, Wang C, Vander Kooi CW, Jia J. Phosphatidic acid binding to Patched contributes to the inhibition of Smoothened and Hedgehog signaling in Drosophila wing development. Sci Signal 2023; 16:eadd6834. [PMID: 37847757 PMCID: PMC10661859 DOI: 10.1126/scisignal.add6834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/25/2023] [Indexed: 10/19/2023]
Abstract
Hedgehog (Hh) signaling controls growth and patterning during embryonic development and homeostasis in adult tissues. Hh binding to the receptor Patched (Ptc) elicits intracellular signaling by relieving Ptc-mediated inhibition of the transmembrane protein Smoothened (Smo). We uncovered a role for the lipid phosphatidic acid (PA) in the regulation of the Hh pathway in Drosophila melanogaster. Deleting the Ptc C-terminal tail or mutating the predicted PA-binding sites within it prevented Ptc from inhibiting Smo in wing discs and in cultured cells. The C-terminal tail of Ptc directly interacted with PA in vitro, an association that was reduced by Hh, and increased the amount of PA at the plasma membrane in cultured cells. Smo also interacted with PA in vitro through a binding pocket located in the transmembrane region, and mutating residues in this pocket reduced Smo activity in vivo and in cells. By genetically manipulating PA amounts in vivo or treating cultured cells with PA, we demonstrated that PA promoted Smo activation. Our findings suggest that Ptc may sequester PA in the absence of Hh and release it in the presence of Hh, thereby increasing the amount of PA that is locally available to promote Smo activation.
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Affiliation(s)
- Jie Zhang
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Yajuan Liu
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Chi Wang
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Craig W. Vander Kooi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jianhang Jia
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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6
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Prakash SJ, Van Auken KM, Hill DP, Sternberg PW. Semantic Representation of Neural Circuit Knowledge in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538760. [PMID: 37162850 PMCID: PMC10168330 DOI: 10.1101/2023.04.28.538760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In modern biology, new knowledge is generated quickly, making it challenging for researchers to efficiently acquire and synthesise new information from the large volume of primary publications. To address this problem, computational approaches that generate machine-readable representations of scientific findings in the form of knowledge graphs have been developed. These representations can integrate different types of experimental data from multiple papers and biological knowledge bases in a unifying data model, providing a complementary method to manual review for interacting with published knowledge. The Gene Ontology Consortium (GOC) has created a semantic modelling framework that extends individual functional gene annotations to structured descriptions of causal networks representing biological processes (Gene Ontology Causal Activity Modelling, or GO-CAM). In this study, we explored whether the GO-CAM framework could represent knowledge of the causal relationships between environmental inputs, neural circuits and behavior in the model nematode C. elegans (C. elegans Neural Circuit Causal Activity Modelling (CeN-CAM)). We found that, given extensions to several relevant ontologies, a wide variety of author statements from the literature about the neural circuit basis of egg-laying and carbon dioxide (CO2) avoidance behaviors could be faithfully represented with CeN-CAM. Through this process, we were able to generate generic data models for several categories of experimental results. We also discuss how semantic modelling may be used to functionally annotate the C. elegans connectome. Thus, Gene Ontology-based semantic modelling has the potential to support various machine-readable representations of neurobiological knowledge.
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Affiliation(s)
- Sharan J Prakash
- 1. Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kimberly M Van Auken
- 1. Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - David P Hill
- 2. The Jackson Laboratory, Bar Harbor, ME, 04609 USA
| | - Paul W Sternberg
- 1. Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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7
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Qiu Z, Lin Z, Hu A, Liu Y, Zeng W, Zhao X, Shi X, Luo J, Song B. GRAMD1/ASTER-mediated cholesterol transport promotes Smoothened cholesterylation at the endoplasmic reticulum. EMBO J 2023; 42:e111513. [PMID: 36524353 PMCID: PMC9890235 DOI: 10.15252/embj.2022111513] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 11/28/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Hedgehog (Hh) signaling pathway plays a pivotal role in embryonic development. Hh binding to Patched1 (PTCH1) derepresses Smoothened (SMO), thereby activating the downstream signal transduction. Covalent SMO modification by cholesterol in its cysteine-rich domain (CRD) is essential for SMO function. SMO cholesterylation is a calcium-accelerated autoprocessing reaction, and STIM1-ORAI1-mediated store-operated calcium entry promotes cholesterylation and activation of endosome-localized SMO. However, it is unknown whether the Hh-PTCH1 interplay regulates the activity of the endoplasmic reticulum (ER)-localized SMO. Here, we found that PTCH1 inhibited the COPII-dependent export of SMO from the ER, whereas Hh promoted this process. The RRxWxR amino acid motif in the cytosolic tail of SMO was essential for COPII recognition, ciliary localization, and signal transduction activity. Hh and PTCH1 regulated cholesterol modification of the ER-localized SMO, and SMO cholesterylation accelerated its exit from ER. The GRAMD1/ASTER sterol transport proteins facilitated cholesterol transfer to ER from PM, resulting in increased SMO cholesterylation and enhanced Hh signaling. Collectively, we reveal a regulatory role of GRAMD-mediated cholesterol transport in ER-resident SMO maturation and Hh signaling.
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Affiliation(s)
- Zhi‐Ping Qiu
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Zi‐Cun Lin
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Ao Hu
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Yuan‐Bin Liu
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Wan‐Er Zeng
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Xiaolu Zhao
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Xiong‐Jie Shi
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Jie Luo
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
| | - Bao‐Liang Song
- College of Life Sciences, Taikang Center for Life and Medical Sciences, Taikang Medical School, Hubei Key Laboratory of Cell HomeostasisWuhan UniversityWuhanChina
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8
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Fan J, Tong G, Chen X, Li S, Yu Y, Zhu S, Zhu K, Hu Z, Dong Y, Chen R, Zhu J, Gong W, Hu Z, Zhou B, Chen Y, Jin L, Cong W. CK2 blockade alleviates liver fibrosis by suppressing activation of hepatic stellate cells via the Hedgehog pathway. Br J Pharmacol 2023; 180:44-61. [PMID: 36070072 DOI: 10.1111/bph.15945] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 08/29/2022] [Accepted: 09/02/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Liver fibrosis is a serious cause of morbidity and mortality worldwide characterized by accumulation of extracellular matrix produced by hepatic stellate cells (HSCs). The protein kinase CK2 is a pro-survival kinase overexpressed in human tumours. However, the biological role of CK2 in liver fibrosis is largely unknown. We aimed to investigate the mechanism by which CK2 promotes liver fibrosis. EXPERIMENTAL APPROACH In vitro, LX-2 cells were stimulated with transforming growth factor-β (TGF-β). HSCs were also isolated for research. In vivo, the adeno-associated virus AAV-sh-csnk2a1 was used to knockdown CK2α specifically in HSCs, and CX-4945 was used to pharmacologically inhibit the enzymatic activity of CK2 in murine models of fibrosis induced by carbon tetrachloride (CCl4 ) and a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet. Histological and biochemical analyses were performed to study the involvement of CK2 in regulation of fibrogenic and fibrolytic factors as well as activation properties of HSCs. KEY RESULTS HSC-specific genetic invalidation of CK2α or pharmacological inhibition of CK2 protected mice treated with CCl4 or fed a DDC diet against liver fibrosis and HSC accumulation. Mechanistically, CK2α, which bound to Smoothened (SMO), was a positive regulator of the Hedgehog signal transduction pathway. CK2 prevented ubiquitination and proteasomal degradation of SMO, which was abolished by knockdown of CK2α or pharmacological inhibition of CK2. CONCLUSIONS AND IMPLICATIONS CK2 activation is critical to sustain the activated and fibrogenic phenotype of HSCs via SMO stabilization. Therefore, inactivation of CK2 by CX-4945 may be of therapeutic interest for liver fibrotic diseases.
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Affiliation(s)
- Junfu Fan
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Gaozan Tong
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xixi Chen
- Department of Pharmacy, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, Zhejiang, China
| | - Santie Li
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ying Yu
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Shunan Zhu
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Kunxuan Zhu
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zijing Hu
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yonggan Dong
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Rui Chen
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Junjie Zhu
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Wenjie Gong
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zhicheng Hu
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Bin Zhou
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yiming Chen
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Litai Jin
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Weitao Cong
- School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
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Jiang J. Hedgehog signaling mechanism and role in cancer. Semin Cancer Biol 2022; 85:107-122. [PMID: 33836254 PMCID: PMC8492792 DOI: 10.1016/j.semcancer.2021.04.003] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/25/2021] [Accepted: 04/02/2021] [Indexed: 12/12/2022]
Abstract
Cell-cell communication through evolutionarily conserved signaling pathways governs embryonic development and adult tissue homeostasis. Deregulation of these signaling pathways has been implicated in a wide range of human diseases including cancer. One such pathway is the Hedgehog (Hh) pathway, which was originally discovered in Drosophila and later found to play a fundamental role in human development and diseases. Abnormal Hh pathway activation is a major driver of basal cell carcinomas (BCC) and medulloblastoma. Hh exerts it biological influence through a largely conserved signal transduction pathway from the activation of the GPCR family transmembrane protein Smoothened (Smo) to the conversion of latent Zn-finger transcription factors Gli/Ci proteins from their repressor (GliR/CiR) to activator (GliA/CiA) forms. Studies from model organisms and human patients have provided deep insight into the Hh signal transduction mechanisms, revealed roles of Hh signaling in a wide range of human cancers, and suggested multiple strategies for targeting this pathway in cancer treatment.
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Affiliation(s)
- Jin Jiang
- Department of Molecular Biology and Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390, USA.
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10
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Jia J, Jiang J. Regulation of Smoothened Trafficking and Abundance in Hedgehog Signaling. Front Cell Dev Biol 2022; 10:847844. [PMID: 35321245 PMCID: PMC8936432 DOI: 10.3389/fcell.2022.847844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 02/23/2022] [Indexed: 12/02/2022] Open
Abstract
The GPCR-family protein Smoothened (Smo) is essential for Hedgehog (Hh) signal transduction in both insects and vertebrates. The regulation of subcellular localization and abundance of Smo is a critical step in Hh signaling. Recent studies have demonstrated that Smo is subjected to ubiquitination mediated by multiple E3 ubiquitin ligases, leading to Smo endocytosis and subsequent degradation through the proteasome- and lysosome-mediated pathways in Drosophila. Ubiquitination of Smo also promotes its ciliary exit in mammalian cells. Hh inhibits Smo ubiquitination by blocking E3 ligase recruitment and promoting Smo deubiquitination through the ubiquitin-specific protease 8 (USP8) in Drosophila. Inhibition of Smo ubiquitination by Hh promotes Smo cell surface accumulation in Drosophila and ciliary accumulation in mammalian cells. Interestingly, Hh also induces sumoylation of Smo in both Drosophila and mammalian cells, which promotes Smo cell surface/ciliary accumulation. This review focuses on how ubiquitination and sumoylation regulate Smo intracellular trafficking and abundance and how these processes are regulated by Hh.
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Affiliation(s)
- Jianhang Jia
- Department of Molecular and Cellular Biochemistry, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jin Jiang
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX, United States
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11
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Cholesterylation of Smoothened is a calcium-accelerated autoreaction involving an intramolecular ester intermediate. Cell Res 2022; 32:288-301. [PMID: 35121857 PMCID: PMC8888579 DOI: 10.1038/s41422-022-00622-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/10/2022] [Indexed: 12/16/2022] Open
Abstract
Hedgehog (Hh) is a morphogen that binds to its receptor Patched 1 and activates Smoothened (SMO), thereby governing embryonic development and postnatal tissue homeostasis. Cholesterol can bind and covalently conjugate to the luminal cysteine-rich domain (CRD) of human SMO at the D95 residue (D99 in mouse). The reaction mechanism and biological function of SMO cholesterylation have not been elucidated. Here, we show that the SMO-CRD undergoes auto-cholesterylation which is boosted by calcium and involves an intramolecular ester intermediate. In cells, Hh stimulation elevates local calcium concentration in the SMO-localized endosomes through store-operated calcium entry. In addition, we identify the signaling-incompetent SMO D95E mutation, and the D95E mutant SMO can bind cholesterol but cannot be modified or activated by cholesterol. The homozygous SmoD99E/D99E knockin mice are embryonic lethal with severe developmental delay, demonstrating that cholesterylation of CRD is required for full-length SMO activation. Our work reveals the unique autocatalytic mechanism of SMO cholesterylation and an unprecedented role of calcium in Hh signaling.
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12
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Abstract
The Hedgehog (Hh) family of secreted proteins governs embryonic development and adult tissue homeostasis by regulating the abundance, localization, and activity of the GPCR family protein Smoothened (Smo). Smo trafficking and subcellular accumulation are controlled by multiple posttranslational modifications (PTMs) including phosphorylation, ubiquitination, and sumoylation, which appears to be conserved from Drosophila to mammals. Smo ubiquitination is dynamically regulated by E3 ubiquitin ligases and deubiquitinases (dubs) and is opposed by Hh signaling. By contrast, Smo sumoylation is stimulated by Hh, which counteracts Smo ubiquitination by recruiting the dub USP8. We describe cell-base assays for Smo ubiquitination and its regulation by Hh and the E3 ligases in Drosophila. We also describe assays for Smo sumoylation in both Drosophila and mammalian cultured cells.
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Affiliation(s)
- Yuhong Han
- Department of Molecular Biology, UT Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Jin Jiang
- Department of Molecular Biology, UT Southwestern Medical Center at Dallas, Dallas, TX, USA.
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13
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Zhang Q, Jiang J. Regulation of Hedgehog Signal Transduction by Ubiquitination and Deubiquitination. Int J Mol Sci 2021; 22:ijms222413338. [PMID: 34948134 PMCID: PMC8703657 DOI: 10.3390/ijms222413338] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 12/23/2022] Open
Abstract
The Hedgehog (Hh) family of secreted proteins governs embryonic development and adult tissue homeostasis in species ranging from insects to mammals. Deregulation of Hh pathway activity has been implicated in a wide range of human disorders, including congenital diseases and cancer. Hh exerts its biological influence through a conserved signaling pathway. Binding of Hh to its receptor Patched (Ptc), a twelve-span transmembrane protein, leads to activation of an atypical GPCR family protein and Hh signal transducer Smoothened (Smo), which then signals downstream to activate the latent Cubitus interruptus (Ci)/Gli family of transcription factors. Hh signal transduction is regulated by ubiquitination and deubiquitination at multiple steps along the pathway including regulation of Ptc, Smo and Ci/Gli proteins. Here we review the effect of ubiquitination and deubiquitination on the function of individual Hh pathway components, the E3 ubiquitin ligases and deubiquitinases involved, how ubiquitination and deubiquitination are regulated, and whether the underlying mechanisms are conserved from Drosophila to mammals.
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Affiliation(s)
- Qing Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing 210061, China
- MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, School of Medicine, Nanjing University, Nanjing 210061, China
- Correspondence: (Q.Z.); (J.J.)
| | - Jin Jiang
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence: (Q.Z.); (J.J.)
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14
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Molecular basis of ubiquitin-specific protease 8 autoinhibition by the WW-like domain. Commun Biol 2021; 4:1272. [PMID: 34750505 PMCID: PMC8576004 DOI: 10.1038/s42003-021-02802-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/22/2021] [Indexed: 12/26/2022] Open
Abstract
Ubiquitin-specific protease 8 (USP8) is a deubiquitinating enzyme involved in multiple membrane trafficking pathways. The enzyme activity is inhibited by binding to 14-3-3 proteins. Mutations in the 14-3-3-binding motif in USP8 are related to Cushing’s disease. However, the molecular basis of USP8 activity regulation remains unclear. This study identified amino acids 645–684 of USP8 as an autoinhibitory region, which might interact with the catalytic USP domain, as per the results of pull-down and single-molecule FRET assays performed in this study. In silico modelling indicated that the region forms a WW-like domain structure, plugs the catalytic cleft, and narrows the entrance to the ubiquitin-binding pocket. Furthermore, 14-3-3 inhibited USP8 activity partly by enhancing the interaction between the WW-like and USP domains. These findings provide the molecular basis of USP8 autoinhibition via the WW-like domain. Moreover, they suggest that the release of autoinhibition may underlie Cushing’s disease due to USP8 mutations. In order to advance our understanding of the regulation of Ubiquitin-specific protease 8 (USP8), which is known to play a role in Cushing’s Disease, Kakihara et al identify and characterise amino acids 645–684 of USP8, which serve as an autoinhibitory region. Their pull-down and single-molecule FRET analysis, as well as in silico modelling, suggest that the release of USP8 autoinhibition may underlie Cushing’s disease.
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15
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Liu M, Su Y, Peng J, Zhu AJ. Protein modifications in Hedgehog signaling: Cross talk and feedback regulation confer divergent Hedgehog signaling activity. Bioessays 2021; 43:e2100153. [PMID: 34738654 DOI: 10.1002/bies.202100153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/06/2021] [Accepted: 10/12/2021] [Indexed: 12/12/2022]
Abstract
The complexity of the Hedgehog (Hh) signaling cascade has increased over the course of evolution; however, it does not suffice to accommodate the dynamic yet robust requirements of differential Hh signaling activity needed for embryonic development and adult homeostatic maintenance. One solution to solve this dilemma is to apply multiple forms of post-translational modifications (PTMs) to the core Hh signaling components, modulating their abundance, localization, and signaling activity. This review summarizes various forms of protein modifications utilized to regulate Hh signaling, with a special emphasis on crosstalk between different forms of PTMs and their feedback regulation by Hh signaling.
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Affiliation(s)
- Min Liu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Ying Su
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Jingyu Peng
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Alan Jian Zhu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
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16
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Qiu ZP, Hu A, Song BL. The 3-beta-hydroxysteroid-Delta(8), Delta(7)-isomerase EBP inhibits cholesterylation of Smoothened. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:159041. [PMID: 34450268 DOI: 10.1016/j.bbalip.2021.159041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/14/2021] [Accepted: 08/19/2021] [Indexed: 12/21/2022]
Abstract
Hedgehog (Hh) pathway plays a central role in vertebrate embryonic development and carcinogenesis. The G-protein coupled receptor-like protein Smoothened (SMO) is one of the major members in Hh pathway. Covalent modification of cholesterol on the 95th asparagine (D95) of human SMO, which is regulated by Hh and PTCH1, is critical for SMO activation. However, it is not known whether SMO cholesterylation is regulated by other proteins. In this study, we identified Emopamil binding protein (EBP, also known as 3-beta-hydroxysteroid-Delta(8),Delta(7)-isomerase) as a SMO-interacting protein. Overexpression of EBP suppressed SMO cholesterylation and Hh pathway activity, whereas genetic disruption of EBP enhanced SMO cholesterylation and the downstream signaling. EBP-mediated inhibition of SMO cholesterylation was independent of its isomerase activity, but dependent on the C-terminus of EBP that was required for SMO binding. The X-linked dominant chondrodysplasia punctate 2 (CDPX2)-associated EBP mutants inhibited SMO cholesterylation too. Together, this study shows that EBP modulates SMO cholesterylation through direct binding and suggests a possible mechanism of CDPX2 pathogenesis.
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Affiliation(s)
- Zhi-Ping Qiu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Ao Hu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Bao-Liang Song
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.
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17
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Mechanisms of Smoothened Regulation in Hedgehog Signaling. Cells 2021; 10:cells10082138. [PMID: 34440907 PMCID: PMC8391454 DOI: 10.3390/cells10082138] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/05/2021] [Accepted: 08/16/2021] [Indexed: 12/21/2022] Open
Abstract
The seven-transmembrane protein, Smoothened (SMO), has shown to be critical for the hedgehog (HH) signal transduction on the cell membrane (and the cilium in vertebrates). SMO is subjected to multiple types of post-translational regulations, including phosphorylation, ubiquitination, and sumoylation, which alter SMO intracellular trafficking and cell surface accumulation. Recently, SMO is also shown to be regulated by small molecules, such as oxysterol, cholesterol, and phospholipid. The activity of SMO must be very well balanced by these different mechanisms in vivo because the malfunction of SMO will not only cause developmental defects in early stages, but also induce cancers in late stages. Here, we discuss the activation and inactivation of SMO by different mechanisms to better understand how SMO is regulated by the graded HH signaling activity that eventually governs distinct development outcomes.
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18
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Lv B, Stuck MW, Desai PB, Cabrera OA, Pazour GJ. E3 ubiquitin ligase Wwp1 regulates ciliary dynamics of the Hedgehog receptor Smoothened. J Cell Biol 2021; 220:212435. [PMID: 34161574 PMCID: PMC8236919 DOI: 10.1083/jcb.202010177] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 05/01/2021] [Accepted: 06/01/2021] [Indexed: 12/26/2022] Open
Abstract
The Hedgehog pathway, critical to vertebrate development, is organized in primary cilia. Activation of signaling causes the Hedgehog receptor Ptch1 to exit cilia, allowing a second receptor, Smo, to accumulate in cilia and activate the downstream steps of the pathway. Mechanisms regulating the dynamics of these receptors are unknown, but the ubiquitination of Smo regulates its interaction with the intraflagellar transport system to control ciliary levels. A focused screen of ubiquitin-related genes identified nine required for maintaining low ciliary Smo at the basal state. These included cytoplasmic E3s (Arih2, Mgrn1, and Maea), a ciliary localized E3 (Wwp1), a ciliary localized E2 (Ube2l3), a deubiquitinase (Bap1), and three adaptors (Kctd5, Skp1a, and Skp2). The ciliary E3, Wwp1, binds Ptch1 and localizes to cilia at the basal state. Activation of signaling removes both Ptch1 and Wwp1 from cilia, thus providing an elegant mechanism for Ptch1 to regulate ciliary Smo levels.
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Affiliation(s)
- Bo Lv
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Michael W Stuck
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Paurav B Desai
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Oscar A Cabrera
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
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19
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Emmons-Bell M, Hariharan IK. Membrane potential regulates Hedgehog signalling in the Drosophila wing imaginal disc. EMBO Rep 2021; 22:e51861. [PMID: 33629503 PMCID: PMC8024891 DOI: 10.15252/embr.202051861] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/29/2020] [Accepted: 01/15/2021] [Indexed: 01/02/2023] Open
Abstract
While the membrane potential of cells has been shown to be patterned in some tissues, specific roles for membrane potential in regulating signalling pathways that function during development are still being established. In the Drosophila wing imaginal disc, Hedgehog (Hh) from posterior cells activates a signalling pathway in anterior cells near the boundary which is necessary for boundary maintenance. Here, we show that membrane potential is patterned in the wing disc. Anterior cells near the boundary, where Hh signalling is most active, are more depolarized than posterior cells across the boundary. Elevated expression of the ENaC channel Ripped Pocket (Rpk), observed in these anterior cells, requires Hh. Antagonizing Rpk reduces depolarization and Hh signal transduction. Using genetic and optogenetic manipulations, in both the wing disc and the salivary gland, we show that membrane depolarization promotes membrane localization of Smoothened and augments Hh signalling, independently of Patched. Thus, membrane depolarization and Hh‐dependent signalling mutually reinforce each other in cells immediately anterior to the compartment boundary.
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Affiliation(s)
- Maya Emmons-Bell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Iswar K Hariharan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
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20
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Kitagawa T, Takiya S. Regulation of genes for ubiquitination and SUMO‐specific protease involved in larval development of the silkworm,
Bombyx mori. Dev Growth Differ 2020; 62:438-449. [DOI: 10.1111/dgd.12687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 05/26/2020] [Accepted: 05/30/2020] [Indexed: 11/30/2022]
Affiliation(s)
- Tsuyuki Kitagawa
- Graduate School of Life Science Hokkaido University Sapporo Japan
| | - Shigeharu Takiya
- Graduate School of Life Science Hokkaido University Sapporo Japan
- Division of Biological Sciences and Center for Genome Dynamics Faculty of Science Hokkaido University Sapporo Japan
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21
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Jiang W, Yao X, Shan Z, Li W, Gao Y, Zhang Q. E3 ligase Herc4 regulates Hedgehog signalling through promoting Smoothened degradation. J Mol Cell Biol 2020; 11:791-803. [PMID: 30925584 PMCID: PMC7261483 DOI: 10.1093/jmcb/mjz024] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/24/2018] [Accepted: 12/21/2018] [Indexed: 12/21/2022] Open
Abstract
Hedgehog (Hh) signalling plays conserved roles in controlling embryonic development; its dysregulation causes many diseases including cancers. The G protein-coupled receptor Smoothened (Smo) is the key signal transducer of the Hh pathway, whose posttranslational regulation has been shown to be critical for its accumulation and activation. Ubiquitination has been reported an essential posttranslational regulation of Smo. Here, we identify a novel E3 ligase of Smo, Herc4, which binds to Smo, and regulates Hh signalling by controlling Smo ubiquitination and degradation. Interestingly, our data suggest that Herc4-mediated Smo degradation is regulated by Hh in PKA-primed phosphorylation-dependent and independent manners.
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Affiliation(s)
- Weirong Jiang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China
| | - Xia Yao
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China
| | - Zhaoliang Shan
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China
| | - Wenting Li
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China
| | - Yuxue Gao
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China
| | - Qing Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China
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22
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DUBs Activating the Hedgehog Signaling Pathway: A Promising Therapeutic Target in Cancer. Cancers (Basel) 2020; 12:cancers12061518. [PMID: 32531973 PMCID: PMC7352588 DOI: 10.3390/cancers12061518] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/01/2020] [Accepted: 06/06/2020] [Indexed: 12/29/2022] Open
Abstract
The Hedgehog (HH) pathway governs cell proliferation and patterning during embryonic development and is involved in regeneration, homeostasis and stem cell maintenance in adult tissues. The activity of this signaling is finely modulated at multiple levels and its dysregulation contributes to the onset of several human cancers. Ubiquitylation is a coordinated post-translational modification that controls a wide range of cellular functions and signaling transduction pathways. It is mediated by a sequential enzymatic network, in which ubiquitin ligases (E3) and deubiquitylase (DUBs) proteins are the main actors. The dynamic balance of the activity of these enzymes dictates the abundance and the fate of cellular proteins, thus affecting both physiological and pathological processes. Several E3 ligases regulating the stability and activity of the key components of the HH pathway have been identified. Further, DUBs have emerged as novel players in HH signaling transduction, resulting as attractive and promising drug targets. Here, we review the HH-associated DUBs, discussing the consequences of deubiquitylation on the maintenance of the HH pathway activity and its implication in tumorigenesis. We also report the recent progress in the development of selective inhibitors for the DUBs here reviewed, with potential applications for the treatment of HH-related tumors.
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23
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Li Y, Sun X, Gao D, Ding Y, Liu J, Chen J, Luo J, Zhang J, Liu Q, Zhou Z. Dual functions of Rack1 in regulating Hedgehog pathway. Cell Death Differ 2020; 27:3082-3096. [PMID: 32467643 PMCID: PMC7560836 DOI: 10.1038/s41418-020-0563-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 01/20/2023] Open
Abstract
Hedgehog (Hh) pathway plays multiple roles in many physiological processes and its dysregulation leads to congenital disorders and cancers. Hh regulates the cellular localization of Smoothened (Smo) and the stability of Cubitus interruptus (Ci) to fine-tune the signal outputs. However, the underlying mechanisms are still unclear. Here, we show that the scaffold protein Rack1 plays dual roles in Hh signaling. In the absence of Hh, Rack1 promotes Ci and Cos2 to form a Ci–Rack1–Cos2 complex, culminating in Slimb-mediated Ci proteolysis. In the presence of Hh, Rack1 dissociates from Ci–Rack1–Cos2 complex and forms a trimeric complex with Smo and Usp8, leading to Smo deubiquitination and cell surface accumulation. Furthermore, we find the regulation of Rack1 on Hh pathway is conserved from Drosophila to mammalian cells. Our findings demonstrate that Rack1 plays dual roles during Hh signal transduction and provide Rack1 as a potential drug target for Hh-related diseases.
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Affiliation(s)
- Yan Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China
| | - Xiaohan Sun
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China
| | - Dongqing Gao
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China
| | - Yan Ding
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China
| | - Jinxiao Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China
| | - Jiong Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 210061, Nanjing, China
| | - Jun Luo
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 210061, Nanjing, China
| | - Junzheng Zhang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, 100094, Beijing, China
| | - Qingxin Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China.
| | - Zizhang Zhou
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Tai'an, China.
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24
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Qi X, Li X. Mechanistic Insights into the Generation and Transduction of Hedgehog Signaling. Trends Biochem Sci 2020; 45:397-410. [PMID: 32311334 PMCID: PMC7174405 DOI: 10.1016/j.tibs.2020.01.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/19/2020] [Accepted: 01/23/2020] [Indexed: 12/23/2022]
Abstract
Cell differentiation and proliferation require Hedgehog (HH) signaling and aberrant HH signaling causes birth defects or cancers. In this signaling pathway, the N-terminally palmitoylated and C-terminally cholesterylated HH ligand is secreted into the extracellular space with help of the Dispatched-1 (DISP1) and Scube2 proteins. The Patched-1 (PTCH1) protein releases its inhibition of the oncoprotein Smoothened (SMO) after binding the HH ligand, triggering downstream signaling events. In this review, we discuss the recent structural and biochemical studies on four major components of the HH pathway: the HH ligand, DISP1, PTCH1, and SMO. This research provides mechanistic insights into how HH signaling is generated and transduced from the cell surface into the intercellular space and will aid in facilitating the treatment of HH-related diseases.
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Affiliation(s)
- Xiaofeng Qi
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Xiaochun Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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25
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Ubiquitin-specific protease 8 (USP8/UBPy): a prototypic multidomain deubiquitinating enzyme with pleiotropic functions. Biochem Soc Trans 2020; 47:1867-1879. [PMID: 31845722 PMCID: PMC6925526 DOI: 10.1042/bst20190527] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/29/2019] [Accepted: 12/02/2019] [Indexed: 01/07/2023]
Abstract
Protein modification by ubiquitin is one of the most versatile posttranslational regulations and counteracted by almost 100 deubiquitinating enzymes (DUBs). USP8 was originally identified as a growth regulated ubiquitin-specific protease and is like many other DUBs characterized by its multidomain architecture. Besides the catalytic domain, specific protein-protein interaction modules were characterized which contribute to USP8 substrate recruitment, regulation and targeting to distinct protein complexes. Studies in mice and humans impressively showed the physiological relevance and non-redundant function of USP8 within the context of the whole organism. USP8 knockout (KO) mice exhibit early embryonic lethality while induced deletion in adult animals rapidly causes lethal liver failure. Furthermore, T-cell specific ablation disturbs T-cell development and function resulting in fatal autoimmune inflammatory bowel disease. In human patients, somatic mutations in USP8 were identified as the underlying cause of adrenocorticotropic hormone (ACTH) releasing pituitary adenomas causing Cushing's disease (CD). Here we provide an overview of the versatile molecular, cellular and pathology associated function and regulation of USP8 which appears to depend on specific protein binding partners, substrates and the cellular context.
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26
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Secreted tyrosine kinase Vlk negatively regulates Hedgehog signaling by inducing lysosomal degradation of Smoothened. Biochem J 2020; 477:121-136. [PMID: 31845979 DOI: 10.1042/bcj20190784] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/05/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022]
Abstract
Vlk is a secreted tyrosine kinase that plays crucial roles during vertebrate embryonic development including skeletal formation. Genetic studies suggest that Vlk can modulate the Hedgehog signaling pathway during skeletal development. Despite its potential roles as an extracellular regulator of signaling pathways, little is known regarding the molecular functions of Vlk. Here we show that Vlk can negatively regulate the Hedgehog signaling pathway. We found that Vlk can induce lysosomal degradation of Smoothened, a crucial transmembrane signal transducer of the Hedgehog pathway, through the interaction with the extracellular domain of Smoothened (Smo-ECD). In addition, we observed that Vlk can attenuate Hedgehog signaling-induced ciliary localization of Smoothened. Furthermore, Vlk-mediated suppression of Hedgehog signaling can be diminished by tyrosine-to-phenylalanine substitutions in Smo-ECD. Taken together, these results suggest that Vlk may function as a signaling regulator in extracellular space to modulate the Hedgehog pathway.
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27
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PKAc-directed interaction and phosphorylation of Ptc is required for Hh signaling inhibition in Drosophila. Cell Discov 2019; 5:44. [PMID: 31636957 PMCID: PMC6796939 DOI: 10.1038/s41421-019-0112-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 07/04/2019] [Indexed: 01/20/2023] Open
Abstract
Ptc is a gatekeeper to avoid abnormal Hh signaling activation, but the key regulators involved in Ptc-mediated inhibition remain largely unknown. Here, we identify PKAc as a key regulator required for Ptc inhibitory function. In the absence of Hh, PKAc physically interacts with Ptc and phosphorylates Ptc at Ser-1150 and -1183 residues. The presence of Hh unleashes PKAc from Ptc and activates Hh signaling. By combining both in vitro and in vivo functional assays, we demonstrate that such Ptc–PKAc interaction and Ptc phosphorylation are both important for Ptc inhibitory function. Interestingly, we further demonstrate that PKAc is subjected to palmitoylation, contributing to its kinase activity on plasma membrane. Based on those novel findings, we establish a working model on Ptc inhibitory function: In the absence of Hh, PKAc interacts with and phosphorylates Ptc to ensure its inhibitory function; and Hh presence releases PKAc from Ptc, resulting in Hh signaling activation.
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28
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Zhang J, Liu Y, Jiang K, Jia J. Hedgehog signaling promotes lipolysis in adipose tissue through directly regulating Bmm/ATGL lipase. Dev Biol 2019; 457:128-139. [PMID: 31550483 DOI: 10.1016/j.ydbio.2019.09.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/21/2019] [Accepted: 09/20/2019] [Indexed: 01/20/2023]
Abstract
Hedgehog (Hh) signaling has been shown to regulate multiple developmental processes, however, it is unclear how it regulates lipid metabolism. Here, we demonstrate that Hh signaling exhibits potent activity in Drosophila fat body, which is induced by both locally expressed and midgut-derived Hh proteins. Inactivation of Hh signaling increases, whereas activation of Hh signaling decreases lipid accumulation. The major lipase Brummer (Bmm) acts downstream of Smoothened (Smo) in Hh signaling to promote lipolysis, therefore, the breakdown of triacylglycerol (TAG). We identify a critical Ci binding site in bmm promoter that is responsible to mediate Bmm expression induced by Hh signaling. Genomic mutation of the Ci binding site significantly reduces the expression of Bmm and dramatically decreases the responsiveness to Ci overexpression. Together, our findings provide a model for lipolysis to be regulated by Hh signaling, raising the possibility for Hh signaling to be involved in lipid metabolic and/or lipid storage diseases.
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Affiliation(s)
- Jie Zhang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Yajuan Liu
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Kai Jiang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
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29
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Zhou Z, Yao X, Pang S, Chen P, Jiang W, Shan Z, Zhang Q. The deubiquitinase UCHL5/UCH37 positively regulates Hedgehog signaling by deubiquitinating Smoothened. J Mol Cell Biol 2019; 10:243-257. [PMID: 28992318 DOI: 10.1093/jmcb/mjx036] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 08/21/2017] [Indexed: 01/20/2023] Open
Abstract
The Hedgehog (Hh) signaling pathway plays important roles in developmental processes including pattern formation and tissue homeostasis. The seven-pass transmembrane receptor Smoothened (Smo) is the pivotal transducer in the pathway; it, and thus the pathway overall, is regulated by ubiquitin-mediated degradation, which occurs in the absence of Hh. In the presence of Hh, the ubiquitination levels of Smo are decreased, but the molecular basis for this outcome is not well understood. Here, we identify the deubiquitinase UCHL5 as a positive regulator of the Hh pathway. We provide both genetic and biochemical evidence that UCHL5 interacts with and deubiquitinates Smo, increasing stability and promoting accumulation at the cell membrane. Strikingly, we find that Hh enhances the interaction between UCHL5 and Smo, thereby stabilizing Smo. We also find that proteasome subunit RPN13, an activator of UCHL5, could enhance the effect of UCHL5 on Smo protein level. More importantly, we find that the mammalian counterpart of UCHL5, UCH37, plays the same role in the regulation of Hh signaling by modulating hSmo ubiquitination and stability. Our findings thus identify UCHL5/UCH37 as a critical regulator of Hh signaling and potential therapeutic target for cancers.
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Affiliation(s)
- Zizhang Zhou
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
| | - Xia Yao
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
| | - Shu Pang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
| | - Ping Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
| | - Weirong Jiang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
| | - Zhaoliang Shan
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
| | - Qing Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, China.,Collaborative Innovation Center of Genetics and Development, Shanghai, China
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30
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Huang Y, Fang J, Lu W, Wang Z, Wang Q, Hou Y, Jiang X, Reizes O, Lathia J, Nussinov R, Eng C, Cheng F. A Systems Pharmacology Approach Uncovers Wogonoside as an Angiogenesis Inhibitor of Triple-Negative Breast Cancer by Targeting Hedgehog Signaling. Cell Chem Biol 2019; 26:1143-1158.e6. [PMID: 31178408 PMCID: PMC6697584 DOI: 10.1016/j.chembiol.2019.05.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 03/29/2019] [Accepted: 05/13/2019] [Indexed: 02/07/2023]
Abstract
Triple-negative breast cancer (TNBC) is an aggressive and heterogeneous disease that lacks clinically actionable genetic alterations that limit targeted therapies. Here we explore a systems pharmacology approach that integrates drug-target networks and large-scale genomic profiles of TNBC and identify wogonoside, one of the major active flavonoids, as a potent angiogenesis inhibitor. We validate that wogonoside attenuates cell migration, tube formation, and rat aorta microvessel outgrowth, and reduces formation of blood vessels in chicken chorioallantoic membrane and TNBC cell-induced Matrigel plugs. In addition, wogonoside inhibits growth and angiogenesis in TNBC cell xenograft models. This network-based approach predicts, and we empirically validate, wogonoside's antiangiogenic effects resulting from vascular endothelial growth factor secretion. Mechanistically, wogonoside inhibits Gli1 nuclear translocation and transcriptional activities associated with Hedgehog signaling, by promoting Smoothened degradation in a proteasome-dependent mechanism. This study offers a powerful, integrated, systems pharmacology-based strategy for oncological drug discovery and identifies wogonoside as a potential TNBC angiogenesis inhibitor.
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MESH Headings
- Angiogenesis Inhibitors/chemistry
- Angiogenesis Inhibitors/isolation & purification
- Angiogenesis Inhibitors/pharmacology
- Animals
- Antineoplastic Agents, Phytogenic/chemistry
- Antineoplastic Agents, Phytogenic/isolation & purification
- Antineoplastic Agents, Phytogenic/pharmacology
- Biological Products/chemistry
- Biological Products/isolation & purification
- Biological Products/pharmacology
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Drug Screening Assays, Antitumor
- Female
- Flavanones/chemistry
- Flavanones/isolation & purification
- Flavanones/pharmacology
- Glucosides/chemistry
- Glucosides/isolation & purification
- Glucosides/pharmacology
- Hedgehog Proteins/antagonists & inhibitors
- Hedgehog Proteins/metabolism
- Humans
- Mammary Neoplasms, Experimental/drug therapy
- Mammary Neoplasms, Experimental/metabolism
- Mammary Neoplasms, Experimental/pathology
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Scutellaria baicalensis/chemistry
- Signal Transduction/drug effects
- Triple Negative Breast Neoplasms/drug therapy
- Triple Negative Breast Neoplasms/metabolism
- Triple Negative Breast Neoplasms/pathology
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Affiliation(s)
- Yujie Huang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China
| | - Jiansong Fang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China; Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
| | - Weiqiang Lu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China.
| | - Zihao Wang
- Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Qi Wang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China
| | - Yuan Hou
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Xingwu Jiang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Ofer Reizes
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Justin Lathia
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Ruth Nussinov
- Computational Structural Biology Section, Basic Science Program, Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA; Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Charis Eng
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Feixiong Cheng
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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31
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Hu A, Song BL. The interplay of Patched, Smoothened and cholesterol in Hedgehog signaling. Curr Opin Cell Biol 2019; 61:31-38. [PMID: 31369952 DOI: 10.1016/j.ceb.2019.06.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/29/2019] [Accepted: 06/30/2019] [Indexed: 12/29/2022]
Abstract
The Hedgehog (HH) pathway plays a pivotal role in regulating a diverse array of events from embryonic tissue patterning to adult organ self-renewal. Aberrant activation of the pathway is linked to carcinogenesis. Key factors in the HH pathway include the signaling ligand HH, the receptor Patched (PTCH), and the G-protein-coupled receptor-like transducer Smoothened (SMO). A long-lasting question about this pathway is how PTCH prevents SMO from being activated. Recent high-resolution structural studies provide insight into the molecular basis of HH recognition by PTCH. Moreover, cholesterol stands out as the endogenous ligand of SMO and acts by binding and/or covalently linking to SMO. In this review, we discuss current advances in HH signaling, the interplay of PTCH, SMO and cholesterol, and propose putative models of SMO activation by cholesterol binding and/or modification.
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Affiliation(s)
- Ao Hu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Bao-Liang Song
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.
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32
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Structure-function analysis of β-arrestin Kurtz reveals a critical role of receptor interactions in downregulation of GPCR signaling in vivo. Dev Biol 2019; 455:409-419. [PMID: 31325455 DOI: 10.1016/j.ydbio.2019.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/15/2019] [Accepted: 07/16/2019] [Indexed: 01/14/2023]
Abstract
Arrestins control signaling via the G protein coupled receptors (GPCRs), serving as both signal terminators and transducers. Previous studies identified several structural elements in arrestins that contribute to their functions as GPCR regulators. However, the importance of these elements in vivo is unclear, and the developmental roles of arrestins are not well understood. We carried out an in vivo structure-function analysis of Kurtz (Krz), the single ortholog of mammalian β-arrestins in the Drosophila genome. A combination of Krz mutations affecting the GPCR-phosphosensing and receptor core-binding ("finger loop") functions (Krz-KKVL/A) resulted in a complete loss of Krz activity during development. Endosome recruitment and bioluminescence resonance energy transfer (BRET) assays revealed that the KKVL/A mutations abolished the GPCR-binding ability of Krz. We found that the isolated "finger loop" mutation (Krz-VL/A), while having a negligible effect on GPCR internalization, severely affected Krz function, suggesting that tight receptor interactions are necessary for proper termination of signaling in vivo. Genetic analysis as well as live imaging demonstrated that mutations in Krz led to hyperactivity of the GPCR Mist (also known as Mthl1), which is activated by its ligand Folded gastrulation (Fog) and is responsible for cellular contractility and epithelial morphogenesis. Krz mutations affected two developmental events that are under the control of Fog-Mist signaling: gastrulation and morphogenesis of the wing. Overall, our data reveal the functional importance in vivo of direct β-arrestin/GPCR binding, which is mediated by the recognition of the phosphorylated receptor tail and receptor core interaction. These Krz-GPCR interactions are critical for setting the correct level of Fog-Mist signaling during epithelial morphogenesis.
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33
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Abstract
The hedgehog (Hh) pathway plays an important role in cancer development and maintenance, as ~25% of all cancers have aberrant Hh pathway activation. Targeted therapy for inhibition of the Hh pathway was thought to be promising for achieving clinical response in the Hh-dependent cancers. However, the results of new clinical trials with smoothened (SMO) antagonists do not show much success in cancers other than basal cell carcinoma. The studies suggest that the Hh pathway involves multiple mechanisms of activation or inhibition in primary cilia and interactions between several related pathways in different types of cells, which makes this pathway extremely complex. The SMO-specific antagonists may not stop all relevant pathways that may lead to escape or development of resistance. Therefore, in the Hh-dependent cancers, the inhibition of two or more oncogenic pathways (including the Hh pathway) with use of a single agent of a suitable multitarget profile or a combination of drugs seems promising for achieving clinical response in patients and decrease in resistance development with prolonged use of the specific SMO antagonists. Furthermore, for studying the effect of new treatments, the inclusion criteria should be more specific for selection of patients with aberrant Hh pathway activity confirmed by tests. These considerations will be very helpful for choosing the right patients and the right drugs for the best therapeutic outcome.
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34
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Sun X, Sun B, Cui M, Zhou Z. HERC4 exerts an anti-tumor role through destabilizing the oncoprotein Smo. Biochem Biophys Res Commun 2019; 513:1013-1018. [PMID: 31010679 DOI: 10.1016/j.bbrc.2019.04.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 04/15/2019] [Indexed: 12/26/2022]
Abstract
The GPCR-like transmembrane protein Smoothened (Smo) is an indispensable transducer in Hedgehog (Hh) pathway, its hyperactivation leads to several human cancers, including non-small cell lung cancer (NSCLC). The mechanism governing Smo stability still remains elusive. Here, we perform a modifier screening in Drosophila, and find that the E3 ligase dHerc4 degrades dSmo. Depletion of dherc4 increases dSmo protein and activates Hh pathway. In addition, we reveal that HERC4 is downregulated in NSCLC samples, negative correlating with Smo. HERC4 interacts with Smo reciprocally in NSCLC cells. Finally, we show that knockdown of herc4 activates Hh pathway and promotes NSCLC cell proliferation. Taken together, our studies have demonstrated that HERC4 acts as a tumor suppressor via destabilizing the oncoprotein Smo, and provided HERC4 as a promising therapeutic target for NSCLC treatment.
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Affiliation(s)
- Xiaohan Sun
- College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - Bing Sun
- Department of Anorectum, Qianfo Mount Hospital Affiliated to Shandong University, Ji'nan, Shandong, China
| | - Meng Cui
- Department of Anorectum, Qianfo Mount Hospital Affiliated to Shandong University, Ji'nan, Shandong, China.
| | - Zizhang Zhou
- College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China.
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35
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Giordano C, Ruel L, Poux C, Therond P. Protein association changes in the Hedgehog signaling complex mediate differential signaling strength. Development 2018; 145:145/24/dev166850. [PMID: 30541874 DOI: 10.1242/dev.166850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 11/07/2018] [Indexed: 01/20/2023]
Abstract
Hedgehog (Hh) is a conserved morphogen that controls cell differentiation and tissue patterning in metazoans. In Drosophila, the Hh signal is transduced from the G protein-coupled receptor Smoothened (Smo) to the cytoplasmic Hh signaling complex (HSC). How activated Smo is translated into a graded activation of the downstream pathway is still not well understood. In this study, we show that the last amino acids of the cytoplasmic tail of Smo, in combination with G protein-coupled receptor kinase 2 (Gprk2), bind to the regulatory domain of Fused (Fu) and highly activate its kinase activity. We further show that this binding induces changes in the association of Fu protein with the HSC and increases the proximity of the Fu catalytic domain to its substrate, the Costal2 kinesin. We propose a new model in which, depending on the magnitude of Hh signaling, Smo and Gprk2 modulate protein association and conformational changes in the HSC, which are responsible for the differential activation of the pathway.
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Affiliation(s)
- Cecile Giordano
- Université Côte d'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Laurent Ruel
- Université Côte d'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Candice Poux
- Stockholms Universitet, Wenner-Grens Institut, SE-106 91 Stockholm, Sweden
| | - Pascal Therond
- Université Côte d'Azur, CNRS, Inserm, iBV, 06108 Nice, France
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36
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Liu A. Proteostasis in the Hedgehog signaling pathway. Semin Cell Dev Biol 2018; 93:153-163. [PMID: 31429406 DOI: 10.1016/j.semcdb.2018.10.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/11/2018] [Accepted: 10/22/2018] [Indexed: 12/29/2022]
Abstract
The Hedgehog (Hh) signaling pathway is crucial for the development of vertebrate and invertebrate animals alike. Hh ligand binds its receptor Patched (Ptc), allowing the activation of the obligate signal transducer Smoothened (Smo). The levels and localizations of both Ptc and Smo are regulated by ubiquitination, and Smo is under additional regulation by phosphorylation and SUMOylation. Downstream of Smo, the Ci/Gli family of transcription factors regulates the transcriptional responses to Hh. Phosphorylation, ubiquitination and SUMOylation are important for the stability and localization of Ci/Gli proteins and Hh signaling output. Finally, Suppressor of Fused directly regulates Ci/Gli proteins and itself is under proteolytic regulation that is critical for normal Hh signaling.
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Affiliation(s)
- Aimin Liu
- Department of Biology, Eberly College of Science, Huck Institute of Life Sciences, The Pennsylvania State University, University Park, PA, 16802, United States.
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37
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Li S, Cho YS, Wang B, Li S, Jiang J. Regulation of Smoothened ubiquitylation and cell surface expression through a Cul4-DDB1-Gβ E3 ubiquitin ligase complex. J Cell Sci 2018; 131:jcs.218016. [PMID: 29930086 DOI: 10.1242/jcs.218016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/15/2018] [Indexed: 12/21/2022] Open
Abstract
Hedgehog (Hh) transduces signals by promoting cell surface accumulation and activation of the G-protein-coupled receptor (GPCR)-family protein Smoothened (Smo) in Drosophila, but the molecular mechanism underlying the regulation of Smo trafficking remains poorly understood. Here, we identified the Cul4-DDB1 E3 ubiquitin ligase complex as being essential for Smo ubiquitylation and cell surface clearance. We found that the C-terminal intracellular domain of Smo recruits Cul4-DDB1 through the β subunit of trimeric G protein (Gβ), and that Cul4-DDB1-Gβ promotes the ubiquitylation of both Smo and its binding partner G-protein-coupled-receptor kinase 2 (Gprk2) and induces the internalization and degradation of Smo. Hh dissociates Cul4-DDB1 from Smo by recruiting the catalytic subunit of protein kinase A (PKA) to phosphorylate DDB1, which disrupts its interaction with Gβ. Inactivation of the Cul4-DDB1 complex resulted in elevated Smo cell surface expression, whereas an excessive amount of Cul4-DDB1 blocked Smo accumulation and attenuated Hh pathway activation. Taken together, our study identifies an E3 ubiquitin ligase complex targeting Smo for ubiquitylation and provides new insight into how Hh signaling regulates Smo trafficking and cell surface expression.
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Affiliation(s)
- Shuang Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Yong Suk Cho
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Bing Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Shuangxi Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Jin Jiang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA .,Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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38
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Praktiknjo SD, Saad F, Maier D, Ip P, Hipfner DR. Activation of Smoothened in the Hedgehog pathway unexpectedly increases Gα s-dependent cAMP levels in Drosophila. J Biol Chem 2018; 293:13496-13508. [PMID: 30018136 DOI: 10.1074/jbc.ra118.001953] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 07/13/2018] [Indexed: 12/28/2022] Open
Abstract
Hedgehog (Hh) signaling plays a key role in the development and maintenance of animal tissues. This signaling is mediated by the atypical G protein-coupled receptor (GPCR) Smoothened (Smo). Smo activation leads to signaling through several well-characterized effectors to activate Hh target gene expression. Recent studies have implicated activation of the heterotrimeric G protein subunit Gαi and the subsequent decrease in cellular cAMP levels in promoting the Hh response in flies and mammals. Although Hh stimulation decreases cAMP levels in some insect cell lines, here using a bioluminescence resonance energy transfer (BRET)-based assay we found that this stimulation had no detectable effect in Drosophila S2-R+ cells. However, we observed an unexpected and significant Gαs-dependent increase in cAMP levels in response to strong Smo activation in Smo-transfected cells. This effect was mediated by Smo's broadly conserved core, and was specifically activated in response to phosphorylation of the Smo C-terminus by GPCR kinase 2 (Gprk2). Genetic analysis of heterotrimeric G protein function in the developing Drosophila wing revealed a positive role for cAMP in the endogenous Hh response. Specifically, we found that mutation or depletion of Gαs diminished low-threshold Hh responses in Drosophila, whereas depletion of Gαi potentiated them (in contrast to previous findings). Our analysis suggested that regulated cAMP production is important for controlling the sensitivity of cellular responses to Hh in Drosophila.
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Affiliation(s)
- Samantha D Praktiknjo
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,the Departments of Anatomy and Cell Biology and
| | - Farah Saad
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,Biology, McGill University, Montreal, Quebec H3A 0C7, and
| | - Dominic Maier
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,the Departments of Anatomy and Cell Biology and
| | - Pamela Ip
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,the Departments of Anatomy and Cell Biology and
| | - David R Hipfner
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7, .,the Departments of Anatomy and Cell Biology and.,Biology, McGill University, Montreal, Quebec H3A 0C7, and.,the Département de médecine, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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39
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From intra- to extracellular vesicles: extracellular vesicles in developmental signalling. Essays Biochem 2018; 62:215-223. [DOI: 10.1042/ebc20180001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 03/02/2018] [Accepted: 03/06/2018] [Indexed: 12/12/2022]
Abstract
Signalling from cell-to-cell is fundamental for determining differentiation and patterning. This communication can occur between adjacent and distant cells. Extracellular vesicles (EVs) are membrane-based structures thought to facilitate the long-distance movement of signalling molecules. EVs have recently been found to allow the transport of two major developmental signalling pathways: Hedgehog and Wnt. These signalling molecules undergo crucial post-translational lipid modifications, which anchor them to membranes and impede their free release into the extracellular space. Preparation of these ligands in EVs involves intracellular vesicle sorting in an endocytosis-dependent recycling process before secretion. In the present review, we discuss the most recent advances with regard to EV involvement in developmental signalling at a distance. We focus on the role of the protein complexes involved in EV genesis, and provide a comprehensive perspective of the contribution of these complexes to intracellular vesicle sorting of developmental signals for their extracellular secretion, reception and transduction.
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40
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Sun J, Hu Q, Peng H, Peng C, Zhou L, Lu J, Huang C. The ubiquitin-specific protease USP8 deubiquitinates and stabilizes Cx43. J Biol Chem 2018; 293:8275-8284. [PMID: 29626091 DOI: 10.1074/jbc.ra117.001315] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/26/2018] [Indexed: 11/06/2022] Open
Abstract
Connexin-43 (Cx43, also known as GJA1) is the most ubiquitously expressed connexin isoform in mammalian tissues. It forms intercellular gap junction (GJ) channels, enabling adjacent cells to communicate both electrically and metabolically. Cx43 is a short-lived protein which can be quickly degraded by the ubiquitin-dependent proteasomal, endolysosomal, and autophagosomal pathways. Here, we report that the ubiquitin-specific peptidase 8 (USP8) interacts with and deubiquitinates Cx43. USP8 reduces both multiple monoubiquitination and polyubiquitination of Cx43 to prevent autophagy-mediated degradation. Consistently, knockdown of USP8 results in decreased Cx43 protein levels in cultured cells and suppresses intercellular communication, revealed by the dye transfer assay. In human breast cancer specimens, the expression levels of USP8 and Cx43 proteins are positively correlated. Taken together, these results identified USP8 as a crucial and bona fide deubiquitinating enzyme involved in autophagy-mediated degradation of Cx43.
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Affiliation(s)
- Jian Sun
- Department of Breast Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025
| | - Qianwen Hu
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hong Peng
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Cheng Peng
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Liheng Zhou
- Department of Breast Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025
| | - Jinsong Lu
- Department of Breast Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025.
| | - Chuanxin Huang
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
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41
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Li S, Li S, Wang B, Jiang J. Hedgehog reciprocally controls trafficking of Smo and Ptc through the Smurf family of E3 ubiquitin ligases. Sci Signal 2018; 11:11/516/eaan8660. [PMID: 29438012 DOI: 10.1126/scisignal.aan8660] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hedgehog (Hh) induces signaling by promoting the reciprocal trafficking of its receptor Patched (Ptc) and the signal transducer Smoothened (Smo), which is inhibited by Ptc, at the cell surface. We identified Smurf family E3 ubiquitin ligases as essential for Smo ubiquitylation and cell surface clearance and demonstrated that Smurf family members mediate the reciprocal trafficking of Ptc and Smo in Drosophila melanogaster G protein-coupled receptor kinase 2 (Gprk2)-mediated phosphorylation of Smurf promoted Smo ubiquitylation by increasing the recruitment of Smurf to Smo, whereas protein kinase A (PKA)-mediated phosphorylation of Smo caused Smurf to dissociate from Smo, thereby inhibiting Smo ubiquitylation. Smo and Ptc competed for the same pool of Smurf family E3 ubiquitin ligases, and Hh promoted Ptc ubiquitylation and degradation by disrupting the association of Smurf family E3 ubiquitin ligases with Smo and stimulating their binding to Ptc. Our study identifies the E3 ubiquitin ligases that target Smo and provides insight into how Hh regulates the reciprocal trafficking of its receptor and signal transducer.
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Affiliation(s)
- Shuang Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Shuangxi Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Bing Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Jin Jiang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA. .,Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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Jiang K, Liu Y, Zhang J, Jia J. An intracellular activation of Smoothened that is independent of Hedgehog stimulation in Drosophila. J Cell Sci 2018; 131:jcs211367. [PMID: 29142103 PMCID: PMC5818065 DOI: 10.1242/jcs.211367] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/13/2017] [Indexed: 01/09/2023] Open
Abstract
Smoothened (Smo), a GPCR family protein, plays a critical role in the reception and transduction of Hedgehog (Hh) signal. Smo is phosphorylated and activated on the cell surface; however, it is unknown whether Smo can be intracellularly activated. Here, we demonstrate that inactivation of the ESCRT-III causes dramatic accumulation of Smo in the ESCRT-III/MVB compartment, and subsequent activation of Hh signaling. In contrast, inactivation of ESCRTs 0-II induces mild Smo accumulation in the ESCRT-III/MVB compartment. We provide evidence that Kurtz (Krz), the Drosophila β-arrestin2, acts in parallel with the ESCRTs 0-II pathway to sort Smo to the multivesicular bodies and lysosome-mediated degradation. Additionally, upon inactivation of ESCRT-III, all active and inactive forms of Smo are accumulated. Endogenous Smo accumulated upon ESCRT-III inactivation is highly activated, which is induced by phosphorylation but not sumoylation. Taken together, our findings demonstrate a model for intracellular activation of Smo, raising the possibility for tissue overgrowth caused by an excessive amount, rather than mutation of Smo.
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Affiliation(s)
- Kai Jiang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Yajuan Liu
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jie Zhang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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A cell based, high throughput assay for quantitative analysis of Hedgehog pathway activation using a Smoothened activation sensor. Sci Rep 2017; 7:14341. [PMID: 29085027 PMCID: PMC5662767 DOI: 10.1038/s41598-017-14767-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 06/13/2017] [Indexed: 02/06/2023] Open
Abstract
The Hedgehog (Hh) signalling cascade plays an important role in development and disease. In the absence of Hh ligand, activity of the key signal transducer Smoothened (Smo) is downregulated by the Hh receptor Patched (Ptc). However, the mechanisms underlying this inhibition, and especially its release upon ligand stimulation, are still poorly understood, in part because tools for following Smo activation at the subcellular level were long lacking. To address this deficit we have developed a high throughput cell culture assay based on a fluorescent sensor for Drosophila Smo activation. We have screened a small molecule inhibitor library, and observed increased Smo sensor fluorescence with compounds aimed at two major target groups, the MAPK signalling cascade and polo and aurora kinases. Biochemical validation for selected inhibitors (dobrafenib, tak-733, volasertib) confirmed the screen results and revealed differences in the mode of Smo activation. Furthermore, monitoring Smo activation at the single cell level indicated that individual cells exhibit different threshold responses to Hh stimulation, which may be mechanistically relevant for the formation of graded Hh responses. Together, these results thus provide proof of principle that our assay may become a valuable tool for dissecting the cell biological basis of Hh pathway activation.
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Abstract
Signaling pathways direct organogenesis, often through concentration-dependent effects on cells. The hedgehog pathway enables cells to sense and respond to hedgehog ligands, of which the best studied is sonic hedgehog. Hedgehog signaling is essential for development, proliferation, and stem cell maintenance, and it is a driver of certain cancers. Lipid metabolism has a profound influence on both hedgehog signal transduction and the properties of the ligands themselves, leading to changes in the strength of hedgehog signaling and cellular functions. Here we review the evolving understanding of the relationship between lipids and hedgehog signaling.
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Affiliation(s)
- Robert Blassberg
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - John Jacob
- Nuffield Department of Clinical Neurosciences (NDCN), Level 6, West Wing, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. .,Department of Neurology, West Wing, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. .,Milton Keynes University Hospital, Standing Way, Eaglestone, Milton Keynes, MK6 5LD, UK.
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Zhao L, Wang L, Chi C, Lan W, Su Y. The emerging roles of phosphatases in Hedgehog pathway. Cell Commun Signal 2017; 15:35. [PMID: 28931407 PMCID: PMC5607574 DOI: 10.1186/s12964-017-0191-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/14/2017] [Indexed: 01/12/2023] Open
Abstract
Hedgehog signaling is evolutionarily conserved and plays a pivotal role in cell fate determination, embryonic development, and tissue renewal. As aberrant Hedgehog signaling is tightly associated with a broad range of human diseases, its activities must be precisely controlled. It has been known that several core components of Hedgehog pathway undergo reversible phosphorylations mediated by protein kinases and phosphatases, which acts as an effective regulatory mechanism to modulate Hedgehog signal activities. In contrast to kinases that have been extensively studied in these phosphorylation events, phosphatases were thought to function in an unspecific manner, thus obtained much less emphasis in the past. However, in recent years, increasing evidence has implicated that phosphatases play crucial and specific roles in the context of developmental signaling, including Hedgehog signaling. In this review, we present a summary of current progress on phosphatase studies in Hedgehog pathway, emphasizing the multiple employments of protein serine/threonine phosphatases during the transduction of morphogenic Hedgehog signal in both Drosophila and vertebrate systems, all of which provide insights into the importance of phosphatases in the specific regulation of Hedgehog signaling.
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Affiliation(s)
- Long Zhao
- Cardiovascular Research Center, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129, USA
| | - Liguo Wang
- Institute of Evolution & Marine Biodiversity, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Chunli Chi
- Institute of Evolution & Marine Biodiversity, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Wenwen Lan
- Institute of Evolution & Marine Biodiversity, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Ying Su
- Institute of Evolution & Marine Biodiversity, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
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Spatial Activation of TORC1 Is Regulated by Hedgehog and E2F1 Signaling in the Drosophila Eye. Dev Cell 2017; 42:363-375.e4. [PMID: 28829944 DOI: 10.1016/j.devcel.2017.07.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 06/17/2017] [Accepted: 07/23/2017] [Indexed: 01/20/2023]
Abstract
Target of rapamycin complex 1 (TORC1) regulates cell growth in response to nutrients and growth factors. Although TORC1 signaling has been thoroughly studied at the cellular level, the regulation of TORC1 in multicellular tissues and organs has remained elusive. Here we found that TORC1 is selectively activated in the second mitotic wave (SMW), the terminal synchronous cell division, of the developing Drosophila eye. We demonstrated that Hedgehog (Hh) signaling regulates TORC1 through E2F1 and the cyclin D/Cdk4 complex in the SMW, and this regulation is independent from insulin and amino acid signaling pathways. TORC1 is necessary for the proper G1/S transition of the cells, and the activation of TORC1 rescues the cell-cycle defect of Hh signaling-deficient cells in the SMW. Based on this evolutionarily conserved regulation of TORC1 by Hh signaling, we propose that Hh-dependent developmental signaling pathways spatially regulate TORC1 activity in multicellular organisms.
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Shao J, Xu L, Chen L, Lu Q, Xie X, Shi W, Xiong H, Shi C, Huang X, Mei J, Rao H, Lu H, Lu N, Luo S. Arl13b Promotes Gastric Tumorigenesis by Regulating Smo Trafficking and Activation of the Hedgehog Signaling Pathway. Cancer Res 2017; 77:4000-4013. [PMID: 28611043 PMCID: PMC5540784 DOI: 10.1158/0008-5472.can-16-2461] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 03/21/2017] [Accepted: 06/05/2017] [Indexed: 12/23/2022]
Abstract
Inhibitors of the Hedgehog (Hh) pathway transducer Smoothened (Smo) have been approved for cancer treatment, but Smo mutations often lead to tumor resistance and it remains unclear how Smo is regulated. In this study, we identified the small GTPase Arl13b as a novel partner and regulator of Smo. Arl13b regulated Smo stability, trafficking, and localization, which are each crucial for Hh signaling. In gastric cancer cells, Arl13b stimulated proliferation, migration, and invasion in vitro and in vivo In clinical specimens of gastric cancer, Arl13b expression correlated strongly with tumor size and depth of invasion; patients with high levels of Arl13b had a poor prognosis. Our results show how Arl13b participates in Hh pathway activation in gastric cancer. Cancer Res; 77(15); 4000-13. ©2017 AACR.
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Affiliation(s)
- Jia Shao
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Linlin Xu
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Limin Chen
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Quqin Lu
- Department of Epidemiology & Biostatistics, School of Public Health, Nanchang University, Nanchang, Jiangxi, China
| | - Xinsheng Xie
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Wei Shi
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Huanting Xiong
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Chao Shi
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Xuan Huang
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Jinhong Mei
- Department of Pathology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Hai Rao
- Department of Molecular Medicine, University of Texas Health, San Antonio, Texas
| | - Hua Lu
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Nonghua Lu
- Institute of Digestive Disease, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Shiwen Luo
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China.
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48
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Deubiquitylating enzymes in receptor endocytosis and trafficking. Biochem J 2017; 473:4507-4525. [PMID: 27941029 DOI: 10.1042/bcj20160826] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/15/2016] [Accepted: 09/16/2016] [Indexed: 12/25/2022]
Abstract
In recent times, our knowledge of the roles ubiquitin plays in multiple cellular processes has expanded exponentially, with one example being the role of ubiquitin in receptor endocytosis and trafficking. This has prompted a multitude of studies examining how the different machinery involved in the addition and removal of ubiquitin can influence this process. Multiple deubiquitylating enzymes (DUBs) have been implicated either in facilitating receptor endocytosis and lysosomal degradation or in rescuing receptor levels by preventing endocytosis and/or promoting recycling to the plasma membrane. In this review, we will discuss in detail what is currently known about the role of DUBs in regulating the endocytosis of various transmembrane receptors and ion channels. We will also expand upon the role DUBs play in receptor sorting at the multivesicular body to determine whether a receptor is recycled or trafficked to the lysosome for degradation. Finally, we will briefly discuss how the DUBs implicated in these processes may contribute to the pathogenesis of a range of diseases, and thus the potential these have as therapeutic targets.
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Sanial M, Bécam I, Hofmann L, Behague J, Argüelles C, Gourhand V, Bruzzone L, Holmgren RA, Plessis A. Dose-dependent transduction of Hedgehog relies on phosphorylation-based feedback between the G-protein-coupled receptor Smoothened and the kinase Fused. Development 2017; 144:1841-1850. [PMID: 28360132 DOI: 10.1242/dev.144782] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/20/2017] [Indexed: 12/28/2022]
Abstract
Smoothened (SMO) is a G-protein-coupled receptor-related protein required for the transduction of Hedgehog (HH). The HH gradient leads to graded phosphorylation of SMO, mainly by the PKA and CKI kinases. How thresholds in HH morphogen regulate SMO to promote switch-like transcriptional responses is a central unsolved issue. Using the wing imaginal disc model in Drosophila, we identified new SMO phosphosites that enhance the effects of the PKA/CKI kinases on SMO accumulation, its localization at the plasma membrane and its activity. Surprisingly, phosphorylation at these sites is induced by the kinase Fused (FU), a known downstream effector of SMO. In turn, activation of SMO induces FU to act on its downstream targets. Overall, our data provide evidence for a SMO/FU positive regulatory loop nested within a multikinase phosphorylation cascade. We propose that this complex interplay amplifies signaling above a threshold that allows high HH signaling.
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Affiliation(s)
- Matthieu Sanial
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Isabelle Bécam
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Line Hofmann
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Julien Behague
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Camilla Argüelles
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Vanessa Gourhand
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Lucia Bruzzone
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Robert A Holmgren
- Department of Molecular Bioscience, Northwestern University, Evanston, IL 60208-3500, USA
| | - Anne Plessis
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
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Abstract
Newly synthesized transmembrane proteins undergo a series of steps to ensure that only the required amount of correctly folded protein is localized to the membrane. The regulation of protein quality and its abundance at the membrane are often controlled by ubiquitination, a multistep enzymatic process that results in the attachment of ubiquitin, or chains of ubiquitin to the target protein. Protein ubiquitination acts as a signal for sorting, trafficking, and the removal of membrane proteins via endocytosis, a process through which multiple ubiquitin ligases are known to specifically regulate the functions of a number of ion channels, transporters, and signaling receptors. Endocytic removal of these proteins through ubiquitin-dependent endocytosis provides a way to rapidly downregulate the physiological outcomes, and defects in such controls are directly linked to human pathologies. Recent evidence suggests that ubiquitination is also involved in the shedding of membranes and associated proteins as extracellular vesicles, thereby not only controlling the cell surface levels of some membrane proteins, but also their potential transport to neighboring cells. In this review, we summarize the mechanisms and functions of ubiquitination of membrane proteins and provide specific examples of ubiquitin-dependent regulation of membrane proteins.
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Affiliation(s)
- Natalie Foot
- Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Tanya Henshall
- Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia, Adelaide, Australia
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