1
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Wofford W, Kim J, Kim D, Janneh AH, Lee HG, Atilgan FC, Oleinik N, Kassir MF, Saatci O, Chakraborty P, Tokat UM, Gencer S, Howley B, Howe P, Mehrotra S, Sahin O, Ogretmen B. Alterations of ceramide synthesis induce PD-L1 internalization and signaling to regulate tumor metastasis and immunotherapy response. Cell Rep 2024; 43:114532. [PMID: 39046874 DOI: 10.1016/j.celrep.2024.114532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 05/17/2024] [Accepted: 07/09/2024] [Indexed: 07/27/2024] Open
Abstract
Programmed death ligand 1, PD-L1 (CD274), facilitates immune evasion and exerts pro-survival functions in cancer cells. Here, we report a mechanism whereby internalization of PD-L1 in response to alterations of bioactive lipid/ceramide metabolism by ceramide synthase 4 (CerS4) induces sonic hedgehog (Shh) and transforming growth factor β receptor signaling to enhance tumor metastasis in triple-negative breast cancers (TNBCs), exhibiting immunotherapy resistance. Mechanistically, data showed that internalized PD-L1 interacts with an RNA-binding protein, caprin-1, to stabilize Shh/TGFBR1/Wnt mRNAs to induce β-catenin signaling and TNBC growth/metastasis, consistent with increased infiltration of FoxP3+ regulatory T cells and resistance to immunotherapy. While mammary tumors developed in MMTV-PyMT/CerS4-/- were highly metastatic, targeting the Shh/PD-L1 axis using sonidegib and anti-PD-L1 antibody vastly decreased tumor growth and metastasis, consistent with the inhibition of PD-L1 internalization and Shh/Wnt signaling, restoring anti-tumor immune response. These data, validated in clinical samples and databases, provide a mechanism-based therapeutic strategy to improve immunotherapy responses in metastatic TNBCs.
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Affiliation(s)
- Wyatt Wofford
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Jisun Kim
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Dosung Kim
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Alhaji H Janneh
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Han Gyul Lee
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - F Cansu Atilgan
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Natalia Oleinik
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Mohamed Faisal Kassir
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Ozge Saatci
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Paramita Chakraborty
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Department of Surgery, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Unal Metin Tokat
- Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey
| | - Salih Gencer
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Istanbul Medipol University, Health Science and Technologies Research Institute (SABİTA), Cancer Research Center, Istanbul, Turkey
| | - Breege Howley
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Philip Howe
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Shikhar Mehrotra
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Department of Surgery, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Ozgur Sahin
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Besim Ogretmen
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA; Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA.
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2
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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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3
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Peris I, Romero-Murillo S, Vicente C, Narla G, Odero MD. Regulation and role of the PP2A-B56 holoenzyme family in cancer. Biochim Biophys Acta Rev Cancer 2023; 1878:188953. [PMID: 37437699 DOI: 10.1016/j.bbcan.2023.188953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/07/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer.
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Affiliation(s)
- Irene Peris
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.
| | - Silvia Romero-Murillo
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain
| | - Carmen Vicente
- Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, The University of Michigan Medical School, Ann Arbor, MI, USA
| | - Maria D Odero
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; CIBERONC, Instituto de Salud Carlos III, Madrid, Spain.
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4
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Zhou M, Han Y, Wang B, Cho YS, Jiang J. Dose-dependent phosphorylation and activation of Hh pathway transcription factors. Life Sci Alliance 2022; 5:5/11/e202201570. [PMID: 36271509 PMCID: PMC9445324 DOI: 10.26508/lsa.202201570] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/23/2022] [Accepted: 08/23/2022] [Indexed: 11/24/2022] Open
Abstract
Graded Hedgehog (Hh) signaling is mediated by graded Cubitus interruptus (Ci)/Gli transcriptional activity, but how the Hh gradient is converted into the Ci/Gli activity gradient remains poorly understood. Here, we show that graded Hh induces a progressive increase in Ci phosphorylation at multiple Fused (Fu)/CK1 sites including a cluster located in the C-terminal Sufu-binding domain. We demonstrated that Fu directly phosphorylated Ci on S1382, priming CK1 phosphorylation on adjacent sites, and that Fu/CK1-mediated phosphorylation of the C-terminal sites interfered with Sufu binding and facilitated Ci activation. Phosphorylation at the N-terminal, middle, and C-terminal Fu/CK1 sites occurred independently of one another and each increased progressively in response to increasing levels of Hh or increasing amounts of Hh exposure time. Increasing the number of phospho-mimetic mutations of Fu/CK1 sites resulted in progressively increased Ci activation by alleviating Sufu-mediated inhibition. We found that the C-terminal Fu/CK1 phosphorylation cluster is conserved in Gli2 and contributes to its dose-dependent activation. Our study suggests that the Hh signaling gradient is translated into a Ci/Gli phosphorylation gradient that activates Ci/Gli by gradually releasing Sufu-mediated inhibition.
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Affiliation(s)
- Mengmeng Zhou
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yuhong Han
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bing Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yong Suk Cho
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jin Jiang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA .,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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5
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Altunoglu U, Börklü E, Shukla A, Escande-Beillard N, Ledig S, Azaklı H, Nayak SS, Eraslan S, Girisha KM, Kennerknecht I, Kayserili H. Expanding the spectrum of syndromic PPP2R3C-related XY gonadal dysgenesis to XX gonadal dysgenesis. Clin Genet 2021; 101:221-232. [PMID: 34750818 DOI: 10.1111/cge.14086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/20/2021] [Accepted: 11/04/2021] [Indexed: 01/09/2023]
Abstract
Homozygous variants in PPP2R3C have been reported to cause a syndromic 46,XY complete gonadal dysgenesis phenotype with extragonadal manifestations (GDRM, MIM# 618419) in patients from four unrelated families, whereas heterozygous variants have been linked to reduced fertility with teratozoospermia (SPGF36, MIM# 618420) in male carriers. We present eight patients from four unrelated families of Turkish and Indian descent with three different germline homozygous PPP2R3C variants including a novel in-frame duplication (c.639_647dupTTTCTACTC, p.Ser216_Tyr218dup). All patients exhibit recognizable facial dysmorphisms allowing gestalt diagnosis. In two 46,XX patients with hypergonadotropic hypogonadism and nonvisualized gonads, primary amenorrhea along with absence of secondary sexual characteristics and/or unique facial gestalt led to the diagnosis. 46,XY affected individuals displayed a spectrum of external genital phenotypes from ambiguous genitalia to complete female. We expand the spectrum of syndromic PPP2R3C-related XY gonadal dysgenesis to both XY and XX gonadal dysgenesis. Our findings supported neither ocular nor muscular involvement as major criteria of the syndrome. We also did not encounter infertility problems in the carriers. Since both XX and XY individuals were affected, we hypothesize that PPP2R3C is essential in the early signaling cascades controlling sex determination in humans.
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Affiliation(s)
- Umut Altunoglu
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Medical Genetics Department, Istanbul University Istanbul Medical School, Istanbul, Turkey
| | - Esra Börklü
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Nathalie Escande-Beillard
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Institute of Medical Biology, A*STAR, Singapore, Singapore
| | - Susanne Ledig
- Institut für Humangenetik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany
| | - Hülya Azaklı
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Shalini S Nayak
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Serpil Eraslan
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Katta Mohan Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Ingo Kennerknecht
- Institut für Humangenetik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany
| | - Hülya Kayserili
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Medical Genetics Department, Istanbul University Istanbul Medical School, Istanbul, Turkey
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6
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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: 0.7] [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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7
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Salem Wehbe L, Barakat D, Acker A, El Khoury R, Reichhart JM, Matt N, El Chamy L. Protein Phosphatase 4 Negatively Regulates the Immune Deficiency-NF-κB Pathway during the Drosophila Immune Response. THE JOURNAL OF IMMUNOLOGY 2021; 207:1616-1626. [PMID: 34452932 DOI: 10.4049/jimmunol.1901497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 07/07/2021] [Indexed: 12/31/2022]
Abstract
The evolutionarily conserved immune deficiency (IMD) signaling pathway shields Drosophila against bacterial infections. It regulates the expression of antimicrobial peptides encoding genes through the activation of the NF-κB transcription factor Relish. Tight regulation of the signaling cascade ensures a balanced immune response, which is otherwise highly harmful. Several phosphorylation events mediate intracellular progression of the IMD pathway. However, signal termination by dephosphorylation remains largely elusive. Here, we identify the highly conserved protein phosphatase 4 (PP4) complex as a bona fide negative regulator of the IMD pathway. RNA interference-mediated gene silencing of PP4-19c, PP4R2, and Falafel, which encode the catalytic and regulatory subunits of the phosphatase complex, respectively, caused a marked upregulation of bacterial-induced antimicrobial peptide gene expression in both Drosophila melanogaster S2 cells and adult flies. Deregulated IMD signaling is associated with reduced lifespan of PP4-deficient flies in the absence of any infection. In contrast, flies overexpressing this phosphatase are highly sensitive to bacterial infections. Altogether, our results highlight an evolutionarily conserved function of PP4c in the regulation of NF-κB signaling from Drosophila to mammals.
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Affiliation(s)
- Layale Salem Wehbe
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and.,Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
| | - Dana Barakat
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and.,Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
| | - Adrian Acker
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
| | - Rita El Khoury
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and.,Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
| | | | - Nicolas Matt
- Université de Strasbourg, CNRS, M3I UPR 9022, Strasbourg, France; and
| | - Laure El Chamy
- Unité de Recherche Environnement, Génomique et Protéomique, Faculté des Sciences, Université Saint-Joseph de Beyrouth-Liban, Mar Roukos, Mkalles, Beirut, Lebanon
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8
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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: 11] [Impact Index Per Article: 3.7] [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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9
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Serifi I, Besta S, Karetsou Z, Giardoglou P, Beis D, Niewiadomski P, Papamarcaki T. Targeting of SET/I2PP2A oncoprotein inhibits Gli1 transcription revealing a new modulator of Hedgehog signaling. Sci Rep 2021; 11:13940. [PMID: 34230583 PMCID: PMC8260731 DOI: 10.1038/s41598-021-93440-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 06/18/2021] [Indexed: 01/17/2023] Open
Abstract
The Hedgehog (Hh)/Gli signaling pathway controls cell proliferation and differentiation, is critical for the development of nearly every tissue and organ in vertebrates and is also involved in tumorigenesis. In this study, we characterize the oncoprotein SET/I2PP2A as a novel regulator of Hh signaling. Our previous work has shown that the zebrafish homologs of SET are expressed during early development and localized in the ciliated organs. In the present work, we show that CRISPR/Cas9-mediated knockdown of setb gene in zebrafish embryos resulted in cyclopia, a characteristic patterning defect previously reported in Hh mutants. Consistent with these findings, targeting setb gene using CRISPR/Cas9 or a setb morpholino, reduced Gli1-dependent mCherry expression in the Hedgehog reporter zebrafish line Tg(12xGliBS:mCherry-NLS). Likewise, SET loss of function by means of pharmacological inhibition and gene knockdown prevented the increase of Gli1 expression in mammalian cells in vitro. Conversely, overexpression of SET resulted in an increase of the expression of a Gli-dependent luciferase reporter, an effect likely attributable to the relief of the Sufu-mediated inhibition of Gli1. Collectively, our data support the involvement of SET in Gli1-mediated transcription and suggest the oncoprotein SET/I2PP2A as a new modulator of Hedgehog signaling.
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Affiliation(s)
- Iliana Serifi
- Laboratory of Biological Chemistry, Medical Department, School of Health Sciences, University of Ioannina, 451 10, Ioannina, Greece.,Department of Biomedical Research, Foundation for Research and Technology-Hellas, Institute of Molecular Biology and Biotechnology, 451 10, Ioannina, Greece
| | - Simoni Besta
- Laboratory of Biological Chemistry, Medical Department, School of Health Sciences, University of Ioannina, 451 10, Ioannina, Greece
| | - Zoe Karetsou
- Laboratory of Biological Chemistry, Medical Department, School of Health Sciences, University of Ioannina, 451 10, Ioannina, Greece
| | - Panagiota Giardoglou
- Developmental Biology, Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation Academy of Athens, 115 27, Athens, Greece
| | - Dimitris Beis
- Developmental Biology, Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation Academy of Athens, 115 27, Athens, Greece
| | | | - Thomais Papamarcaki
- Laboratory of Biological Chemistry, Medical Department, School of Health Sciences, University of Ioannina, 451 10, Ioannina, Greece. .,Department of Biomedical Research, Foundation for Research and Technology-Hellas, Institute of Molecular Biology and Biotechnology, 451 10, Ioannina, Greece.
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10
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Merk DJ, Zhou P, Cohen SM, Pazyra-Murphy MF, Hwang GH, Rehm KJ, Alfaro J, Reid CM, Zhao X, Park E, Xu PX, Chan JA, Eck MJ, Nazemi KJ, Harwell CC, Segal RA. The Eya1 Phosphatase Mediates Shh-Driven Symmetric Cell Division of Cerebellar Granule Cell Precursors. Dev Neurosci 2021; 42:170-186. [PMID: 33472197 DOI: 10.1159/000512976] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/10/2020] [Indexed: 12/14/2022] Open
Abstract
During neural development, stem and precursor cells can divide either symmetrically or asymmetrically. The transition between symmetric and asymmetric cell divisions is a major determinant of precursor cell expansion and neural differentiation, but the underlying mechanisms that regulate this transition are not well understood. Here, we identify the Sonic hedgehog (Shh) pathway as a critical determinant regulating the mode of division of cerebellar granule cell precursors (GCPs). Using partial gain and loss of function mutations within the Shh pathway, we show that pathway activation determines spindle orientation of GCPs, and that mitotic spindle orientation correlates with the mode of division. Mechanistically, we show that the phosphatase Eya1 is essential for implementing Shh-dependent GCP spindle orientation. We identify atypical protein kinase C (aPKC) as a direct target of Eya1 activity and show that Eya1 dephosphorylates a critical threonine (T410) in the activation loop. Thus, Eya1 inactivates aPKC, resulting in reduced phosphorylation of Numb and other components that regulate the mode of division. This Eya1-dependent cascade is critical in linking spindle orientation, cell cycle exit and terminal differentiation. Together these findings demonstrate that a Shh-Eya1 regulatory axis selectively promotes symmetric cell divisions during cerebellar development by coordinating spindle orientation and cell fate determinants.
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Affiliation(s)
- Daniel J Merk
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Pengcheng Zhou
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Samuel M Cohen
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Maria F Pazyra-Murphy
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Grace H Hwang
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Kristina J Rehm
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jose Alfaro
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Christopher M Reid
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Xuesong Zhao
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Eunyoung Park
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Pin-Xian Xu
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, USA
| | - Jennifer A Chan
- Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Michael J Eck
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Kellie J Nazemi
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, USA
| | - Corey C Harwell
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA,
| | - Rosalind A Segal
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
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11
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Park J, Lee DH. Functional roles of protein phosphatase 4 in multiple aspects of cellular physiology: a friend and a foe. BMB Rep 2021. [PMID: 32192570 PMCID: PMC7196183 DOI: 10.5483/bmbrep.2020.53.4.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein phosphatase 4 (PP4), one of serine/threonine phosphatases, is involved in many critical cellular pathways, including DNA damage response (DNA repair, cell cycle regulation, and apoptosis), tumorigenesis, cell migration, immune response, stem cell development, glucose metabolism, and diabetes. PP4 has been steadily studied over the past decade about wide spectrum of physiological activities in cells. Given the many vital functions in cells, PP4 has great potential to develop into the finding of key working mechanisms and effective treatments for related diseases such as cancer and diabetes. In this review, we provide an overview of the cellular and molecular mechanisms by which PP4 impacts and also discuss the functional significance of it in cell health.
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Affiliation(s)
- Jaehong Park
- School of Biological Sciences and Biotechnology Graduate School, Chonnam National University, Gwangju 61186, Korea
| | - Dong-Hyun Lee
- Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju 61186; Research Center of Ecomimetics, Chonnam National University, Gwangju 61186, Korea
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12
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Gu S, Yan M, Wang C, Meng X, Xiang Z, Qiu Y, Han X. Microcystin-leucine-arginine induces liver fibrosis by activating the Hedgehog pathway in hepatic stellate cells. Biochem Biophys Res Commun 2020; 533:770-778. [PMID: 32988585 DOI: 10.1016/j.bbrc.2020.09.075] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 09/20/2020] [Indexed: 12/14/2022]
Abstract
Microcystin-leucine-arginine (MC-LR), produced by cyanobacteria, accumulates in the liver through blood circulation. We investigated the impact of MC-LR on liver fibrosis. Mice received a daily injection of MC-LR at various concentrations for 14 consecutive days aa and then mouse liver was obtained for histopathological and immunoblot analysis. Next, a human hepatic stellate cell line (LX-2) was treated with MC-LR at various concentrations followed by measurement of cell viability, cell cycle and relevant protein expression levels. Our data confirmed the induction of mouse liver fibrosis after exposure to MC-LR at 15 μg/kg and 30 μg/kg. Furthermore, we demonstrated that LX-2 cells could uptake MC-LR, resulting in cell proliferation and differentiation through impacting the Hedgehog signaling after the treatment of MC-LR at 50 nM. Our data supported that MC-LR could induce liver fibrosis by modulating the expression of the transcription factor Gli2 in the Hedgehog signaling in hepatic stellate cells.
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Affiliation(s)
- Shen Gu
- Department of Hepatopancreatobiliary Surgery, Drum Tower Hospital, Medical School of Nanjing University, Zhongshan Road 321, Nanjing, 210008, Jiangsu Province, China; Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu, 210093, China.
| | - Minghao Yan
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu, 210093, China.
| | - Cong Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, China.
| | - Xiannan Meng
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu, 210093, China.
| | - Zou Xiang
- Department of Microbiology and Immunology, Mucosal Immunobiology and Vaccine Research Center, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
| | - Yudong Qiu
- Department of Hepatopancreatobiliary Surgery, Drum Tower Hospital, Medical School of Nanjing University, Zhongshan Road 321, Nanjing, 210008, Jiangsu Province, China.
| | - Xiaodong Han
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu, 210093, China.
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13
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Protein phosphatase 4 promotes Hedgehog signaling through dephosphorylation of Suppressor of fused. Cell Death Dis 2020; 11:686. [PMID: 32826873 PMCID: PMC7442787 DOI: 10.1038/s41419-020-02843-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 01/04/2023]
Abstract
Reversible phosphorylation of Suppressor of fused (Sufu) is essential for Sonic Hedgehog (Shh) signal transduction. Sufu is stabilized under dual phosphorylation of protein kinase A (PKA) and glycogen synthase kinase 3β (GSK3β). Its phosphorylation is reduced with the activation of Shh signaling. However, the phosphatase in this reversible phosphorylation has not been found. Taking advantage of a proteomic approach, we identified Protein phosphatase 4 regulatory subunit 2 (Ppp4r2), an interacting protein of Sufu. Shh signaling promotes the interaction of these two proteins in the nucleus, and Ppp4 also promotes dephosphorylation of Sufu, leading to its degradation and enhancing the Gli1 transcriptional activity. Finally, Ppp4-mediated dephosphorylation of Sufu promotes proliferation of medulloblastoma tumor cells, and expression of Ppp4 is positively correlated with up-regulation of Shh pathway target genes in the Shh-subtype medulloblastoma, underscoring the important role of this regulation in Shh signaling.
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14
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Scheidt T, Alka O, Gonczarowska-Jorge H, Gruber W, Rathje F, Dell’Aica M, Rurik M, Kohlbacher O, Zahedi RP, Aberger F, Huber CG. Phosphoproteomics of short-term hedgehog signaling in human medulloblastoma cells. Cell Commun Signal 2020; 18:99. [PMID: 32576205 PMCID: PMC7310537 DOI: 10.1186/s12964-020-00591-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 05/05/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Aberrant hedgehog (HH) signaling is implicated in the development of various cancer entities such as medulloblastoma. Activation of GLI transcription factors was revealed as the driving force upon pathway activation. Increased phosphorylation of essential effectors such as Smoothened (SMO) and GLI proteins by kinases including Protein Kinase A, Casein Kinase 1, and Glycogen Synthase Kinase 3 β controls effector activity, stability and processing. However, a deeper and more comprehensive understanding of phosphorylation in the signal transduction remains unclear, particularly during early response processes involved in SMO activation and preceding GLI target gene regulation. METHODS We applied temporal quantitative phosphoproteomics to reveal phosphorylation dynamics underlying the short-term chemical activation and inhibition of early hedgehog signaling in HH responsive human medulloblastoma cells. Medulloblastoma cells were treated for 5.0 and 15 min with Smoothened Agonist (SAG) to induce and with vismodegib to inhibit the HH pathway. RESULTS Our phosphoproteomic profiling resulted in the quantification of 7700 and 10,000 phosphosites after 5.0 and 15 min treatment, respectively. The data suggest a central role of phosphorylation in the regulation of ciliary assembly, trafficking, and signal transduction already after 5.0 min treatment. ERK/MAPK signaling, besides Protein Kinase A signaling and mTOR signaling, were differentially regulated after short-term treatment. Activation of Polo-like Kinase 1 and inhibition of Casein Kinase 2A1 were characteristic for vismodegib treatment, while SAG treatment induced Aurora Kinase A activity. Distinctive phosphorylation of central players of HH signaling such as SMO, SUFU, GLI2 and GLI3 was observed only after 15 min treatment. CONCLUSIONS This study provides evidence that phosphorylation triggered in response to SMO modulation dictates the localization of hedgehog pathway components within the primary cilium and affects the regulation of the SMO-SUFU-GLI axis. The data are relevant for the development of targeted therapies of HH-associated cancers including sonic HH-type medulloblastoma. A deeper understanding of the mechanisms of action of SMO inhibitors such as vismodegib may lead to the development of compounds causing fewer adverse effects and lower frequencies of drug resistance. Video Abstract.
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Affiliation(s)
- Tamara Scheidt
- Department of Biosciences, Bioanalytical Research Laboratories and Molecular Cancer Research and Tumor Immunology, Cancer Cluster Salzburg, University of Salzburg, Hellbrunner Straße 34, 5020 Salzburg, Austria
| | - Oliver Alka
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Sand 14, 72076 Tübingen, Germany
| | - Humberto Gonczarowska-Jorge
- Leibniz-Institute of Analytical Sciences- ISAS - e.V, Dortmund, Germany
- Present address: CAPES Foundation, Ministry of Education of Brazil, Brasília, DF 70040-020 Brazil
| | - Wolfgang Gruber
- Department of Biosciences, Bioanalytical Research Laboratories and Molecular Cancer Research and Tumor Immunology, Cancer Cluster Salzburg, University of Salzburg, Hellbrunner Straße 34, 5020 Salzburg, Austria
- Present address: EVER Valinject GmbH, 4866 Unterach am Attersee, Austria
| | - Florian Rathje
- Department of Biosciences, Bioanalytical Research Laboratories and Molecular Cancer Research and Tumor Immunology, Cancer Cluster Salzburg, University of Salzburg, Hellbrunner Straße 34, 5020 Salzburg, Austria
| | | | - Marc Rurik
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Sand 14, 72076 Tübingen, Germany
| | - Oliver Kohlbacher
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Sand 14, 72076 Tübingen, Germany
- Biomolecular Interactions, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
- Institute for Translational Bioinformatics, University Hospital Tübingen, Hoppe-Seyler-Str. 9, 72076 Tübingen, Germany
- Applied Bioinformatics, Center for Bioinformatics, University of Tübingen, Sand 14, 72076 Tübingen, Germany
| | - René P. Zahedi
- Leibniz-Institute of Analytical Sciences- ISAS - e.V, Dortmund, Germany
- Gerald Bronfman Department of Oncology, Jewish General Hospital, McGill University, Montreal, Canada
- Segal Cancer Proteomics Centre, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Canada
| | - Fritz Aberger
- Department of Biosciences, Bioanalytical Research Laboratories and Molecular Cancer Research and Tumor Immunology, Cancer Cluster Salzburg, University of Salzburg, Hellbrunner Straße 34, 5020 Salzburg, Austria
| | - Christian G. Huber
- Department of Biosciences, Bioanalytical Research Laboratories and Molecular Cancer Research and Tumor Immunology, Cancer Cluster Salzburg, University of Salzburg, Hellbrunner Straße 34, 5020 Salzburg, Austria
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15
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Han Y, Wang B, Cho YS, Zhu J, Wu J, Chen Y, Jiang J. Phosphorylation of Ci/Gli by Fused Family Kinases Promotes Hedgehog Signaling. Dev Cell 2019; 50:610-626.e4. [PMID: 31279575 DOI: 10.1016/j.devcel.2019.06.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 04/12/2019] [Accepted: 06/05/2019] [Indexed: 12/13/2022]
Abstract
Hedgehog (Hh) signaling culminates in the conversion of the latent transcription factor Cubitus interruptus (Ci)/Gli into its activator form (CiA/GliA), but the underlying mechanism remains poorly understood. Here, we demonstrate that Hh stimulates the phosphorylation of Ci by the Ser/Thr kinase Fused (Fu) and that Fu-mediated phosphorylation of Ci promotes its activation. We find that Fu directly phosphorylates Ci on Ser218 and Ser1230, which primes its further phosphorylation by CK1 on adjacent sties. These phosphorylation events alter Ci binding to the pathway inhibitor Suppressor of fused (Sufu) and facilitate the recruitment of Transportion and the transcriptional coactivator CBP. Furthermore, we provide evidence that Sonic hedgehog (Shh) activates Gli2 by stimulating its phosphorylation on conserved sites through the Fu-family kinases ULK3 and mFu/STK36 in a manner depending on Gli2 ciliary localization. Hence, Fu-family kinase-mediated phosphorylation of Ci/Gli serves as a conserved mechanism that activates the Hh pathway transcription factor.
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Affiliation(s)
- Yuhong Han
- 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
| | - Yong Suk Cho
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Jian Zhu
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA; Laboratory of Molecular Oncology, School of Laboratory Medicine, Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Henan Province, Xinxiang 453003, China
| | - Jiang Wu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Yongbin Chen
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Yunnan, Kunming 650223, China
| | - 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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16
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Abstract
The term blood-bile barrier (BBlB) refers to the physical structure within a hepatic lobule that compartmentalizes and hence segregates sinusoidal blood from canalicular bile. Thus, this barrier provides physiological protection in the liver, shielding the hepatocytes from bile toxicity and restricting the mixing of blood and bile. BBlB is primarily composed of tight junctions; however, adherens junction, desmosomes, gap junctions, and hepatocyte bile transporters also contribute to the barrier function of the BBlB. Recent findings also suggest that disruption of BBlB is associated with major hepatic diseases characterized by cholestasis and aberrations in BBlB thus may be a hallmark of many chronic liver diseases. Several molecular signaling pathways have now been shown to play a role in regulating the structure and function and eventually contribute to regulation of the BBlB function within the liver. In this review, we will discuss the structure and function of the BBlB, summarize the methods to assess the integrity and function of BBlB, discuss the role of BBlB in liver pathophysiology, and finally, discuss the mechanisms of BBlB regulation. Collectively, this review will demonstrate the significance of the BBlB in both liver homeostasis and hepatic dysfunction.
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Affiliation(s)
- Tirthadipa Pradhan-Sundd
- *Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- †Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Satdarshan Pal Monga
- *Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- †Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- ‡Pittsburgh Liver Research Center, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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17
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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: 22] [Impact Index Per Article: 3.7] [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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18
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A genetic mosaic screen identifies genes modulating Notch signaling in Drosophila. PLoS One 2018; 13:e0203781. [PMID: 30235233 PMCID: PMC6147428 DOI: 10.1371/journal.pone.0203781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 08/27/2018] [Indexed: 01/08/2023] Open
Abstract
Notch signaling is conserved in most multicellular organisms and plays critical roles during animal development. The core components and major signal transduction mechanism of Notch signaling have been extensively studied. However, our understanding of how Notch signaling activity is regulated in diverse developmental processes still remains incomplete. Here, we report a genetic mosaic screen in Drosophila melanogaster that leads to identification of Notch signali ng modulators during wing development. We discovered a group of genes required for the formation of the fly wing margin, a developmental process that is strictly dependent on the balanced Notch signaling activity. These genes encode transcription factors, protein phosphatases, vacuolar ATPases and factors required for RNA transport, stability, and translation. Our data support the view that Notch signaling is controlled through a wide range of molecular processes. These results also provide foundations for further study by showing that Me31B and Wdr62 function as two novel modulators of Notch signaling activity.
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19
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Zhao S, Guan G, Liu J, Liu A, Li Y, Yin H, Luo J. Screening and identification of host proteins interacting with Theileria annulata cysteine proteinase (TaCP) by yeast-two-hybrid system. Parasit Vectors 2017; 10:536. [PMID: 29084576 PMCID: PMC5661931 DOI: 10.1186/s13071-017-2421-0] [Citation(s) in RCA: 21] [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: 05/16/2017] [Accepted: 10/03/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Theileria annulata can infect monocytes/macrophages and B lymphocytes and causes severe lymphoproliferative disease in ruminants. Meanwhile, infection by T. annulata leads to the permanent proliferation of cell population through regulating signaling pathways of host cells. Cysteine proteinases (CPs) are one kind of protein hydrolase and usually play critical roles in parasite virulence, host invasion, nutrition and host immune response. However, the biological function of T. annulata CP (TaCP) is still unclear. In this study, a yeast-two-hybrid assay was performed to screen host proteins interacting with TaCP, to provide information to help our understanding of the molecular mechanisms between T. annulata and host cells. METHODS The cDNA from purified bovine B cells was inserted into pGADT7-SfiI vector (pGADT7-SfiI-BcDNA, Prey plasmid) for constructing the yeast two-hybrid cDNA library. TaCP was cloned into the pGBKT7 vector (pGBKT7-TaCP) and was considered as bait plasmid after evaluating the expression, auto-activation and toxicity tests in the yeast strain Y2HGold. The yeast two-hybrid screening was carried out via co-transforming bait and prey plasmids into yeast strain Y2HGold. Sequences of positive preys were analyzed using BLAST, Gene Ontology, UniProt and STRING. RESULTS Two host proteins, CRBN (Bos taurus cereblon transcript variant X2) and Ppp4C (Bos indicus protein phosphatase 4 catalytic subunit) were identified to interact with TaCP. The results of functional analysis showed that the two proteins were involved in many cellular processes, such as ubiquitylation regulation, microtubule organization, DNA repair, cell apoptosis and maturation of spliceosomal snRNPs. CONCLUSIONS This study is the first to screen the host proteins of bovine B cells interacting with TaCP, and 2 proteins, CRBN and Ppp4C, were identified using yeast two-hybrid technique. The results of functional analysis suggest that the two proteins are involved in many cellular processes, such as ubiquitylation regulating, microtubule organization, DNA repair, cell apoptosis and maturation of spliceosomal snRNPs. The interaction with CRBN and Ppp4C indicate that TaCP possibly is involved in regulating signaling pathways and cell proliferation, which is helpful for understanding the interaction between T. annulata and host cells.
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Affiliation(s)
- Shuaiyang Zhao
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
| | - Guiquan Guan
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
| | - Junlong Liu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
| | - Aihong Liu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
| | - Youquan Li
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
| | - Hong Yin
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009 People’s Republic of China
| | - Jianxun Luo
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu 730046 People’s Republic of China
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20
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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: 0.9] [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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21
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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: 2.0] [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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22
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Hall ET, Pradhan-Sundd T, Samnani F, Verheyen EM. The protein phosphatase 4 complex promotes the Notch pathway and wingless transcription. Biol Open 2017; 6:1165-1173. [PMID: 28652317 PMCID: PMC5576076 DOI: 10.1242/bio.025221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Wnt/Wingless (Wg) pathway controls cell fate specification, tissue differentiation and organ development across organisms. Using an in vivo RNAi screen to identify novel kinase and phosphatase regulators of the Wg pathway, we identified subunits of the serine threonine phosphatase Protein Phosphatase 4 (PP4). Knockdown of the catalytic and regulatory subunits of PP4 cause reductions in the Wg pathway targets Senseless and Distal-less. We find that PP4 regulates the Wg pathway by controlling Notch-driven wg transcription. Genetic interaction experiments identified that PP4 likely promotes Notch signaling within the nucleus of the Notch-receiving cell. Although the PP4 complex is implicated in various cellular processes, its role in the regulation of Wg and Notch pathways was previously uncharacterized. Our study identifies a novel role of PP4 in regulating Notch pathway, resulting in aberrations in Notch-mediated transcriptional regulation of the Wingless ligand. Furthermore, we show that PP4 regulates proliferation independent of its interaction with Notch. Summary: The protein phosphatase 4 complex promotes Notch signaling and target gene expression during Drosophila wing development.
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Affiliation(s)
- Eric T Hall
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Tirthadipa Pradhan-Sundd
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Faaria Samnani
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Esther M Verheyen
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
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23
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SUMO regulates the activity of Smoothened and Costal-2 in Drosophila Hedgehog signaling. Sci Rep 2017; 7:42749. [PMID: 28195188 PMCID: PMC5307382 DOI: 10.1038/srep42749] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/17/2017] [Indexed: 12/21/2022] Open
Abstract
In Hedgehog (Hh) signaling, the GPCR-family protein Smoothened (Smo) acts as a signal transducer that is regulated by phosphorylation and ubiquitination, which ultimately change the cell surface accumulation of Smo. However, it is not clear whether Smo is regulated by other post-translational modifications, such as sumoylation. Here, we demonstrate that knockdown of the small ubiquitin-related modifier (SUMO) pathway components Ubc9 (a SUMO-conjugating enzyme E2), PIAS (a SUMO-protein ligase E3), and Smt3 (the SUMO isoform in Drosophila) by RNAi prevents Smo accumulation and alters Smo activity in the wing. We further show that Hh-induced-sumoylation stabilizes Smo, whereas desumoylation by Ulp1 destabilizes Smo in a phosphorylation independent manner. Mechanistically, we discover that excessive Krz, the Drosophila β-arrestin 2, inhibits Smo sumoylation and prevents Smo accumulation through Krz regulatory domain. Krz likely facilitates the interaction between Smo and Ulp1 because knockdown of Krz by RNAi attenuates Smo-Ulp1 interaction. Finally, we provide evidence that Cos2 is also sumoylated, which counteracts its inhibitory role on Smo accumulation in the wing. Taken together, we have uncovered a novel mechanism for Smo activation by sumoylation that is regulated by Hh and Smo interacting proteins.
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24
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Bandyopadhyay M, Arbet S, Bishop CP, Bidwai AP. Drosophila Protein Kinase CK2: Genetics, Regulatory Complexity and Emerging Roles during Development. Pharmaceuticals (Basel) 2016; 10:E4. [PMID: 28036067 PMCID: PMC5374408 DOI: 10.3390/ph10010004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/12/2016] [Accepted: 12/19/2016] [Indexed: 01/06/2023] Open
Abstract
CK2 is a Ser/Thr protein kinase that is highly conserved amongst all eukaryotes. It is a well-known oncogenic kinase that regulates vital cell autonomous functions and animal development. Genetic studies in the fruit fly Drosophila are providing unique insights into the roles of CK2 in cell signaling, embryogenesis, organogenesis, neurogenesis, and the circadian clock, and are revealing hitherto unknown complexities in CK2 functions and regulation. Here, we review Drosophila CK2 with respect to its structure, subunit diversity, potential mechanisms of regulation, developmental abnormalities linked to mutations in the gene encoding CK2 subunits, and emerging roles in multiple aspects of eye development. We examine the Drosophila CK2 "interaction map" and the eye-specific "transcriptome" databases, which raise the prospect that this protein kinase has many additional targets in the developing eye. We discuss the possibility that CK2 functions during early retinal neurogenesis in Drosophila and mammals bear greater similarity than has been recognized, and that this conservation may extend to other developmental programs. Together, these studies underscore the immense power of the Drosophila model organism to provide new insights and avenues to further investigate developmentally relevant targets of this protein kinase.
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Affiliation(s)
| | - Scott Arbet
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA.
| | - Clifton P Bishop
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA.
| | - Ashok P Bidwai
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA.
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25
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Regulation of Smoothened Trafficking and Hedgehog Signaling by the SUMO Pathway. Dev Cell 2016; 39:438-451. [PMID: 27746045 DOI: 10.1016/j.devcel.2016.09.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 06/14/2016] [Accepted: 09/13/2016] [Indexed: 12/21/2022]
Abstract
Hedgehog (Hh) signaling plays a central role in development and diseases. Hh activates its signal transducer and GPCR-family protein Smoothened (Smo) by inducing Smo phosphorylation, but whether Smo is activated through other post-translational modifications remains unexplored. Here we show that sumoylation acts in parallel with phosphorylation to promote Smo cell-surface expression and Hh signaling. We find that Hh stimulates Smo sumoylation by dissociating it from a desumoylation enzyme Ulp1. Sumoylation of Smo in turn recruits a deubiquitinase UBPY/USP8 to antagonize Smo ubiquitination and degradation, leading to its cell-surface accumulation and elevated Hh pathway activity. We also provide evidence that Shh stimulates sumoylation of mammalian Smo (mSmo) and that sumoylation promotes ciliary localization of mSmo and Shh pathway activity. Our findings reveal a conserved mechanism whereby the SUMO pathway promotes Hh signaling by regulating Smo subcellular localization and shed light on how sumoylation regulates membrane protein trafficking.
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26
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Li J, Song J, Zaytseva YY, Liu Y, Rychahou P, Jiang K, Starr ME, Kim JT, Harris JW, Yiannikouris FB, Katz WS, Nilsson PM, Orho-Melander M, Chen J, Zhu H, Fahrenholz T, Higashi RM, Gao T, Morris AJ, Cassis LA, Fan TWM, Weiss HL, Dobner PR, Melander O, Jia J, Evers BM. An obligatory role for neurotensin in high-fat-diet-induced obesity. Nature 2016; 533:411-5. [PMID: 27193687 PMCID: PMC5484414 DOI: 10.1038/nature17662] [Citation(s) in RCA: 182] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/10/2016] [Indexed: 12/15/2022]
Abstract
Obesity and its associated comorbidities (for example, diabetes mellitus and hepatic steatosis) contribute to approximately 2.5 million deaths annually and are among the most prevalent and challenging conditions confronting the medical profession. Neurotensin (NT; also known as NTS), a 13-amino-acid peptide predominantly localized in specialized enteroendocrine cells of the small intestine and released by fat ingestion, facilitates fatty acid translocation in rat intestine, and stimulates the growth of various cancers. The effects of NT are mediated through three known NT receptors (NTR1, 2 and 3; also known as NTSR1, 2, and NTSR3, respectively). Increased fasting plasma levels of pro-NT (a stable NT precursor fragment produced in equimolar amounts relative to NT) are associated with increased risk of diabetes, cardiovascular disease and mortality; however, a role for NT as a causative factor in these diseases is unknown. Here we show that NT-deficient mice demonstrate significantly reduced intestinal fat absorption and are protected from obesity, hepatic steatosis and insulin resistance associated with high fat consumption. We further demonstrate that NT attenuates the activation of AMP-activated protein kinase (AMPK) and stimulates fatty acid absorption in mice and in cultured intestinal cells, and that this occurs through a mechanism involving NTR1 and NTR3 (also known as sortilin). Consistent with the findings in mice, expression of NT in Drosophila midgut enteroendocrine cells results in increased lipid accumulation in the midgut, fat body, and oenocytes (specialized hepatocyte-like cells) and decreased AMPK activation. Remarkably, in humans, we show that both obese and insulin-resistant subjects have elevated plasma concentrations of pro-NT, and in longitudinal studies among non-obese subjects, high levels of pro-NT denote a doubling of the risk of developing obesity later in life. Our findings directly link NT with increased fat absorption and obesity and suggest that NT may provide a prognostic marker of future obesity and a potential target for prevention and treatment.
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Affiliation(s)
- Jing Li
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Jun Song
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Yekaterina Y Zaytseva
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Yajuan Liu
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Piotr Rychahou
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Kai Jiang
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Marlene E Starr
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Ji Tae Kim
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Jennifer W Harris
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Frederique B Yiannikouris
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Wendy S Katz
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Peter M Nilsson
- Department of Clinical Sciences, Lund University, Malmö, 221 00 Lund, Sweden
- Department of Internal Medicine, Skåne University Hospital, Malmö, 205 02 Malmö, Sweden
| | - Marju Orho-Melander
- Department of Clinical Sciences, Lund University, Malmö, 221 00 Lund, Sweden
| | - Jing Chen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
- Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
- Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Timothy Fahrenholz
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, Kentucky 40536, USA
- Center for Environmental and Systems Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Richard M Higashi
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, Kentucky 40536, USA
- Center for Environmental and Systems Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Tianyan Gao
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Andrew J Morris
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky and Lexington Veterans Affairs Medical Center, Lexington, Kentucky 40536, USA
| | - Lisa A Cassis
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Teresa W-M Fan
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, Kentucky 40536, USA
- Center for Environmental and Systems Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Heidi L Weiss
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Biostatistics, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Paul R Dobner
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Olle Melander
- Department of Clinical Sciences, Lund University, Malmö, 221 00 Lund, Sweden
- Department of Internal Medicine, Skåne University Hospital, Malmö, 205 02 Malmö, Sweden
| | - Jianhang Jia
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - B Mark Evers
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
- Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA
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27
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Jiang K, Liu Y, Fan J, Zhang J, Li XA, Evers BM, Zhu H, Jia J. PI(4)P Promotes Phosphorylation and Conformational Change of Smoothened through Interaction with Its C-terminal Tail. PLoS Biol 2016; 14:e1002375. [PMID: 26863604 PMCID: PMC4749301 DOI: 10.1371/journal.pbio.1002375] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/07/2016] [Indexed: 12/29/2022] Open
Abstract
In Hedgehog (Hh) signaling, binding of Hh to the Patched-Interference Hh (Ptc-Ihog) receptor complex relieves Ptc inhibition on Smoothened (Smo). A longstanding question is how Ptc inhibits Smo and how such inhibition is relieved by Hh stimulation. In this study, we found that Hh elevates production of phosphatidylinositol 4-phosphate (PI(4)P). Increased levels of PI(4)P promote, whereas decreased levels of PI(4)P inhibit, Hh signaling activity. We further found that PI(4)P directly binds Smo through an arginine motif, which then triggers Smo phosphorylation and activation. Moreover, we identified the pleckstrin homology (PH) domain of G protein-coupled receptor kinase 2 (Gprk2) as an essential component for enriching PI(4)P and facilitating Smo activation. PI(4)P also binds mouse Smo (mSmo) and promotes its phosphorylation and ciliary accumulation. Finally, Hh treatment increases the interaction between Smo and PI(4)P but decreases the interaction between Ptc and PI(4)P, indicating that, in addition to promoting PI(4)P production, Hh regulates the pool of PI(4)P associated with Ptc and Smo.
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Affiliation(s)
- Kai Jiang
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Yajuan Liu
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Junkai Fan
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Jie Zhang
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Xiang-An Li
- Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - B. Mark Evers
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- Department of Surgery, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Jianhang Jia
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- * E-mail:
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28
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Abstract
The Hedgehog (Hh) signaling pathway play critical roles in embryonic development and adult tissue homeostasis. A critical step in Hh signal transduction is how Hh receptor Patched (Ptc) inhibits the atypical G protein-coupled receptor Smoothened (Smo) in the absence of Hh and how this inhibition is release by Hh stimulation. It is unlikely that Ptc inhibits Smo by direct interaction. Here we discuss how Hh regulates the phosphorylation and ubiquitination of Smo, leading to cell surface and ciliary accumulation of Smo in Drosophila and vertebrate cells, respectively. In addition, we discuss how PI(4)P phospholipid acts in between Ptc and Smo to regulate Smo phosphorylation and activation in response to Hh stimulation.
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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
| | - 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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Deubiquitinase USP47/UBP64E Regulates β-Catenin Ubiquitination and Degradation and Plays a Positive Role in Wnt Signaling. Mol Cell Biol 2015; 35:3301-11. [PMID: 26169834 DOI: 10.1128/mcb.00373-15] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 07/09/2015] [Indexed: 12/15/2022] Open
Abstract
Wnt signaling plays important roles in development and tumorigenesis. A central question about the Wnt pathway is the regulation of β-catenin. Phosphorylation of β-catenin by CK1α and GSK3 promotes β-catenin binding to β-TrCP, leading to β-catenin degradation through the proteasome. The phosphorylation and ubiquitination of β-catenin have been well characterized; however, it is unknown whether and how a deubiquitinase is involved. In this study, by screening RNA interference (RNAi) libraries, we identified USP47 as a deubiquitinase that prevents β-catenin ubiquitination. Inactivation of USP47 by RNAi increased β-catenin ubiquitination, attenuated Wnt signaling, and repressed cancer cell growth. Furthermore, USP47 deubiquitinates itself, whereas β-TrCP promotes USP47 ubiquitination through interaction with an atypical motif in USP47. Finally, in vivo studies in the Drosophila wing suggest that UBP64E, the USP47 counterpart in Drosophila, is required for Armadillo stabilization and plays a positive role in regulating Wnt target gene expression.
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30
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Li X, Nan A, Xiao Y, Chen Y, Lai Y. PP2A-B56ϵ complex is involved in dephosphorylation of γ-H2AX in the repair process of CPT-induced DNA double-strand breaks. Toxicology 2015; 331:57-65. [PMID: 25772433 DOI: 10.1016/j.tox.2015.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 02/25/2015] [Accepted: 03/11/2015] [Indexed: 10/23/2022]
Abstract
Phosphorylation of histone H2AX (γ-H2AX) in response to DNA double-strand breaks (DSBs) should be eliminated from the sites of DNA damage to fulfill the DNA repair and release cells from the growth arrest. Previous study showed that protein phosphatase 2A (PP2A) interact with γ-H2AX that lead to the dephosphorylation of γ-H2AX. Here, we examined the effects of suppression of PP2A regulatory subunits on dephosphorylation of γ-H2AX in human embryonic kidney epithelial cells (HEK) treated by topoisomerase I inhibitor camptothecin (CPT). We found that cells with suppression of B55α or B56ϵ were more sensitive to DNA damage agents. Suppression of B56ϵ led to persistence of γ-H2AX, resulting in prolonged DSBs repair and increased chromatin instability measured by comet assay. In addition, the deficiency of B56ϵ impaired the cell cycle regulation and the DNA repair pathway of homologous recombination (HR). Notably, we detected that PP2A B56ϵ subunit was involved directly in dephosphorylation of γ-H2AX and translocated from cytoplasm to nucleus upon the treatment of CPT. Our findings demonstrate that PP2A holoenzyme containing B56ϵ is responsible for the dephosphorylation of γ-H2AX and regulation of DNA repair of DSBs induced by CPT.
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Affiliation(s)
- Xiuying Li
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Guangzhou 510182, China; College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Anuo Nan
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Guangzhou 510182, China
| | - Ying Xiao
- College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Yongzhong Chen
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Guangzhou 510182, China
| | - Yandong Lai
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Guangzhou 510182, China.
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31
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Cooperative integration between HEDGEHOG-GLI signalling and other oncogenic pathways: implications for cancer therapy. Expert Rev Mol Med 2015; 17:e5. [PMID: 25660620 PMCID: PMC4836208 DOI: 10.1017/erm.2015.3] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The HEDGEHOG-GLI (HH-GLI) signalling is a key pathway critical in embryonic development, stem cell biology and tissue homeostasis. In recent years, aberrant activation of HH-GLI signalling has been linked to several types of cancer, including those of the skin, brain, lungs, prostate, gastrointestinal tract and blood. HH-GLI signalling is initiated by binding of HH ligands to the transmembrane receptor PATCHED and is mediated by transcriptional effectors that belong to the GLI family, whose activity is finely tuned by a number of molecular interactions and post-translation modifications. Several reports suggest that the activity of the GLI proteins is regulated by several proliferative and oncogenic inputs, in addition or independent of upstream HH signalling. The identification of this complex crosstalk and the understanding of how the major oncogenic signalling pathways interact in cancer is a crucial step towards the establishment of efficient targeted combinatorial treatments. Here we review recent findings on the cooperative integration of HH-GLI signalling with the major oncogenic inputs and we discuss how these cues modulate the activity of the GLI proteins in cancer. We then summarise the latest advances on SMO and GLI inhibitors and alternative approaches to attenuate HH signalling through rational combinatorial therapies.
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32
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Jiang K, Jia J. Analysis of Smoothened Phosphorylation and Activation in Cultured Cells and Wing Discs of Drosophila. Methods Mol Biol 2015; 1322:45-60. [PMID: 26179038 DOI: 10.1007/978-1-4939-2772-2_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Smoothened (Smo) is essential for transduction of the Hedgehog (Hh) signal in both insects and vertebrates. Binding of Hh to Ptc-Ihog relieves the Patched (Ptc)-mediated inhibition of Smo, which allows Smo to activate the cubitus interruptus (Ci)/Gli family of zinc finger transcription factors and thereby induce the expression of Hh target genes, such as decapentaplegic (dpp), ptc, and engrailed (en). The activation of Smo appears to be one of the most important events in Hh signaling. Studies have shown that Hh induces cell surface/ciliary accumulation and phosphorylation of Smo by multiple kinases, including protein kinase A (PKA), casein kinase 1 (CK1), casein kinase 2 (CK2), G protein-coupled receptor kinase 2 (Gprk2), and atypical PKC (aPKC). Here, we describe the assays used to examine the activity of Smo in Hh signaling, including in vitro kinase, ptc-luciferase reporter assay, cell surface accumulation assay, fluorescence resonance energy transfer (FRET) assay, and wing disc immunostaining. These assays are powerful tools to study Smo phosphorylation and activation, which have provided mechanistic insight into a better understanding the mechanisms of Smo regulation.
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Affiliation(s)
- Kai Jiang
- Department of Molecular and Cellular Biochemistry, Markey Cancer Center, University of Kentucky, 741 S. Limestone, BBSRB 373, Lexington, KY, 40536-0509, USA
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33
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Hoffmeister M, Prelle C, Küchler P, Kovacevic I, Moser M, Müller-Esterl W, Oess S. The ubiquitin E3 ligase NOSIP modulates protein phosphatase 2A activity in craniofacial development. PLoS One 2014; 9:e116150. [PMID: 25546391 PMCID: PMC4278855 DOI: 10.1371/journal.pone.0116150] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 12/05/2014] [Indexed: 02/05/2023] Open
Abstract
Holoprosencephaly is a common developmental disorder in humans characterised by incomplete brain hemisphere separation and midface anomalies. The etiology of holoprosencephaly is heterogeneous with environmental and genetic causes, but for a majority of holoprosencephaly cases the genes associated with the pathogenesis could not be identified so far. Here we report the generation of knockout mice for the ubiquitin E3 ligase NOSIP. The loss of NOSIP in mice causes holoprosencephaly and facial anomalies including cleft lip/palate, cyclopia and facial midline clefting. By a mass spectrometry based protein interaction screen we identified NOSIP as a novel interaction partner of protein phosphatase PP2A. NOSIP mediates the monoubiquitination of the PP2A catalytic subunit and the loss of NOSIP results in an increase in PP2A activity in craniofacial tissue in NOSIP knockout mice. We conclude, that NOSIP is a critical modulator of brain and craniofacial development in mice and a candidate gene for holoprosencephaly in humans.
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Affiliation(s)
- Meike Hoffmeister
- Institute for Biochemistry II, Goethe University Frankfurt Medical School, Frankfurt/Main, Germany
| | - Carola Prelle
- Institute for Biochemistry II, Goethe University Frankfurt Medical School, Frankfurt/Main, Germany
| | - Philipp Küchler
- Institute for Biochemistry II, Goethe University Frankfurt Medical School, Frankfurt/Main, Germany
| | - Igor Kovacevic
- Institute for Biochemistry II, Goethe University Frankfurt Medical School, Frankfurt/Main, Germany
| | - Markus Moser
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Werner Müller-Esterl
- Institute for Biochemistry II, Goethe University Frankfurt Medical School, Frankfurt/Main, Germany
| | - Stefanie Oess
- Institute for Biochemistry II, Goethe University Frankfurt Medical School, Frankfurt/Main, Germany
- * E-mail:
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34
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Liu YC, Couzens AL, Deshwar AR, B McBroom-Cerajewski LD, Zhang X, Puviindran V, Scott IC, Gingras AC, Hui CC, Angers S. The PPFIA1-PP2A protein complex promotes trafficking of Kif7 to the ciliary tip and Hedgehog signaling. Sci Signal 2014; 7:ra117. [PMID: 25492966 DOI: 10.1126/scisignal.2005608] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The primary cilium is required for Hedgehog (Hh) signaling in vertebrates. Hh leads to ciliary accumulation and activation of the transmembrane protein Smoothened (Smo) and affects the localization of several pathway components, including the Gli family of transcriptional regulators, within different regions of primary cilia. Genetic analysis indicates that the kinesin protein Kif7 both promotes and inhibits mouse Hh signaling. Using mass spectrometry, we identified liprin-α1 (PPFIA1) and the protein phosphatase PP2A as Kif7-interacting proteins, and we showed that they were important for the trafficking of Kif7 and Gli proteins to the tips of cilia and for the transcriptional output of Hh signaling. Our results suggested that PPFIA1 functioned with PP2A to promote the dephosphorylation of Kif7, triggering Kif7 localization to the tips of primary cilia and promoting Gli transcriptional activity.
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Affiliation(s)
- Yulu C Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - Amber L Couzens
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Ashish R Deshwar
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | - Xiaoyun Zhang
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Vijitha Puviindran
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Ian C Scott
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada. Program in Developmental and Stem Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada. Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Chi-Chung Hui
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada. Program in Developmental and Stem Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Stephane Angers
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada. Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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Hedgehog-regulated atypical PKC promotes phosphorylation and activation of Smoothened and Cubitus interruptus in Drosophila. Proc Natl Acad Sci U S A 2014; 111:E4842-50. [PMID: 25349414 DOI: 10.1073/pnas.1417147111] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Smoothened (Smo) is essential for transduction of the Hedgehog (Hh) signal in both insects and vertebrates. Cell surface/cilium accumulation of Smo is thought to play an important role in Hh signaling, but how the localization of Smo is controlled remains poorly understood. In this study, we demonstrate that atypical PKC (aPKC) regulates Smo phosphorylation and basolateral accumulation in Drosophila wings. Inactivation of aPKC by either RNAi or a mutation inhibits Smo basolateral accumulation and attenuates Hh target gene expression. In contrast, expression of constitutively active aPKC elevates basolateral accumulation of Smo and promotes Hh signaling. The aPKC-mediated phosphorylation of Smo at Ser680 promotes Ser683 phosphorylation by casein kinase 1 (CK1), and these phosphorylation events elevate Smo activity in vivo. Moreover, aPKC has an additional positive role in Hh signaling by regulating the activity of Cubitus interruptus (Ci) through phosphorylation of the Zn finger DNA-binding domain. Finally, the expression of aPKC is up-regulated by Hh signaling in a Ci-dependent manner. Our findings indicate a direct involvement of aPKC in Hh signaling beyond its role in cell polarity.
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36
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Li S, Ma G, Wang B, Jiang J. Hedgehog induces formation of PKA-Smoothened complexes to promote Smoothened phosphorylation and pathway activation. Sci Signal 2014; 7:ra62. [PMID: 24985345 PMCID: PMC4621970 DOI: 10.1126/scisignal.2005414] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hedgehog (Hh) is a secreted glycoprotein that binds its receptor Patched to activate the G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor-like protein Smoothened (Smo). In Drosophila, protein kinase A (PKA) phosphorylates and activates Smo in cells stimulated with Hh. In unstimulated cells, PKA phosphorylates and inhibits the transcription factor Cubitus interruptus (Ci). We found that in cells exposed to Hh, the catalytic subunit of PKA (PKAc) bound to the juxtamembrane region of the carboxyl terminus of Smo. PKA-mediated phosphorylation of Smo further enhanced its association with PKAc to form stable kinase-substrate complexes that promoted the PKA-mediated transphosphorylation of Smo dimers. We identified multiple basic residues in the carboxyl terminus of Smo that were required for interaction with PKAc, Smo phosphorylation, and Hh pathway activation. Hh induced a switch from the association of PKAc with a cytosolic complex of Ci and the kinesin-like protein Costal2 (Cos2) to a membrane-bound Smo-Cos2 complex. Thus, our study uncovers a previously uncharacterized mechanism for regulation of PKA activity and demonstrates that the signal-regulated formation of kinase-substrate complexes plays a central role in Hh signal transduction.
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Affiliation(s)
- Shuang Li
- Department of Developmental Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Guoqiang Ma
- Department of Developmental Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Bing Wang
- Department of Developmental Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Jin Jiang
- Department of Developmental 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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37
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Cammarata M, Parisi MG, Benenati G, Vasta GR, Parrinello N. A rhamnose-binding lectin from sea bass (Dicentrarchus labrax) plasma agglutinates and opsonizes pathogenic bacteria. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 44:332-40. [PMID: 24486534 PMCID: PMC4607264 DOI: 10.1016/j.dci.2014.01.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/19/2014] [Accepted: 01/20/2014] [Indexed: 05/25/2023]
Abstract
The discovery of rhamnose-binding lectins (RBLs) in teleost fish eggs led to the identification of a novel lectin family characterized by a unique sequence motif and a structural fold, and initially proposed to modulate fertilization. Further studies of the RBL tissue localization and gene organization were also suggestive of role(s) in innate immunity. Here we describe the purification, and biochemical and functional characterization of a novel RBL (DlRBL) from sea bass (Dicentrarchus labrax) serum. The purified DlRBL had electrophoretic mobilities corresponding to 24 kDa and 100 kDa under reducing and non-reducing conditions, respectively, suggesting that in plasma the DlRBL is present as a physiological homotetramer. DlRBL subunit transcripts revealed an open reading frame encoding 212 amino acid residues that included two tandemly-arrayed carbohydrate-recognition domains, and an 18-residue signal sequence at the N-terminus. The deduced size of 24.1 kDa for the mature protein was in good agreement with the subunit size of the isolated lectin. Binding activity of DlRBL for rabbit erythrocytes could be inhibited in the presence of rhamnose or galactose, did not require calcium, and was optimal at around 20°C and within the pH 6.5-8.0 range. DlRBL agglutinated Gram positive and Gram negative bacteria, and exposure of formalin-killed Escherichia coli to DlRBL enhanced their phagocytosis by D. labrax peritoneal macrophages relative to the unexposed controls. Taken together, the results suggest that plasma DlRBL may play a role in immune recognition of microbial pathogens and facilitate their clearance by phagocytosis.
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Affiliation(s)
- Matteo Cammarata
- Department of Biological, Chemical, Pharmaceutical Science and Technology, Marine Immunobiology Laboratory, University of Palermo, Via Archirafi 18, Palermo, Italy.
| | - Maria Giovanna Parisi
- Department of Biological, Chemical, Pharmaceutical Science and Technology, Marine Immunobiology Laboratory, University of Palermo, Via Archirafi 18, Palermo, Italy
| | - Gigliola Benenati
- Department of Biological, Chemical, Pharmaceutical Science and Technology, Marine Immunobiology Laboratory, University of Palermo, Via Archirafi 18, Palermo, Italy
| | - Gerardo R Vasta
- Department of Microbiology and Immunology, University of Maryland School of Medicine, UMB, IMET, Suite 236, Columbus Center, 701 East Pratt Street, Baltimore, MD 21202, USA
| | - Nicolò Parrinello
- Department of Biological, Chemical, Pharmaceutical Science and Technology, Marine Immunobiology Laboratory, University of Palermo, Via Archirafi 18, Palermo, Italy
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38
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Fan J, Jiang K, Liu Y, Jia J. Hrs promotes ubiquitination and mediates endosomal trafficking of smoothened in Drosophila hedgehog signaling. PLoS One 2013; 8:e79021. [PMID: 24244405 PMCID: PMC3823941 DOI: 10.1371/journal.pone.0079021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 09/25/2013] [Indexed: 12/21/2022] Open
Abstract
In Hedgehog (Hh) signaling, the seven-transmembrane protein Smoothened (Smo) acts as a signal transducer that is regulated by phosphorylation, ubiquitination, and cell surface accumulation. However, it is not clear how Smo cell surface accumulation and intracellular trafficking are regulated. Here, we demonstrate that inactivation of Hrs by deletion or RNAi accumulates Smo in the late endosome that is marked by late endosome markers. Inactivation of Hrs enhances the wing defects caused by dominant-negative Smo. We show that Hrs promotes Smo ubiquitination, deleting the ubiquitin-interacting-motif (UIM) in Hrs abolishes the ability of Hrs to regulate Smo ubiquitination. However, the UIM domain neither recognizes the ubiquitinated Smo nor directly interacts with Smo. Hrs lacking UIM domain still downregulates Smo activity even though to a less extent. We have characterized that the N-terminus of Hrs directly interacts with the PKA/CK1 phosphorylation clusters to prevent Smo phosphorylation and activation, indicating an ubiquitin-independent regulation of Smo by Hrs. Finally, we found that knockdown of Tsg101 accumulates Smo that is co-localized with Hrs and other late endosome markers. Taken together, our data indicate that Hrs mediates Smo trafficking in the late endosome by not only promoting Smo ubiquitination but also blocking Smo phosphorylation.
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Affiliation(s)
- Junkai Fan
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Kai Jiang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Yajuan Liu
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
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Schwend T, Jin Z, Jiang K, Mitchell BJ, Jia J, Yang J. Stabilization of speckle-type POZ protein (Spop) by Daz interacting protein 1 (Dzip1) is essential for Gli turnover and the proper output of Hedgehog signaling. J Biol Chem 2013; 288:32809-32820. [PMID: 24072710 DOI: 10.1074/jbc.m113.512962] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Hedgehog (Hh) pathway is essential for embryonic development and adult tissue homeostasis. The Gli/Cubitus interruptus (Ci) family of transcription factors acts at the downstream end of the pathway to mediate Hh signaling. Both Hh-dependent and -independent Gli regulatory mechanisms are important for the output of Hh signaling. Daz interacting protein 1 (Dzip1) has bipartite positive and negative functions in the Hh pathway. The positive Hh regulatory function appears to be attributed to a requirement for Dzip1 during ciliogenesis. The mechanism by which Dzip1 inhibits Hh signaling, however, remains largely unclear. We recently found that Dzip1 is required for Gli turnover, which may account for its inhibitory function in Hh signaling. Here, we report that Dzip1 regulates Gli/Ci turnover by preventing degradation of speckle-type POZ protein (Spop), a protein that promotes proteasome-dependent turnover of Gli proteins. We provide evidence that Dzip1 regulates the stability of Spop independent of its function in ciliogenesis. Partial knockdown of Dzip1 to levels insufficient for perturbing ciliogenesis, sensitized Xenopus embryos to Hh signaling, leading to phenotypes that resemble activation of Hh signaling. Importantly, overexpression of Spop was able to restore proper Gli protein turnover and rescue phenotypes in Dzip1-depleted embryos. Consistently, depletion of Dzip1 in Drosophila S2 cells destabilized Hh-induced BTB protein (HIB), the Drosophila homolog of Spop, and increased the level of Ci. Thus, Dzip1-dependent stabilization of Spop/HIB is evolutionarily conserved and essential for proper regulation of Gli/Ci proteins in the Hh pathway.
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Affiliation(s)
- Tyler Schwend
- From the Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802
| | - Zhigang Jin
- From the Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802
| | - Kai Jiang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536-0509
| | - Brian J Mitchell
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536-0509
| | - Jing Yang
- From the Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802,.
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40
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Briscoe J, Thérond PP. The mechanisms of Hedgehog signalling and its roles in development and disease. Nat Rev Mol Cell Biol 2013; 14:416-29. [DOI: 10.1038/nrm3598] [Citation(s) in RCA: 1212] [Impact Index Per Article: 110.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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41
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A targeted genetic modifier screen links the SWI2/SNF2 protein domino to growth and autophagy genes in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2013; 3:815-25. [PMID: 23550128 PMCID: PMC3656729 DOI: 10.1534/g3.112.005496] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Targeted genetic studies can facilitate phenotypic analyses and provide important insights into development and other complex processes. The SWI2/SNF2 DNA-dependent ATPase Domino (Dom) of Drosophila melanogaster, a component of the Tip60 acetyltransferase complex, has been associated with a wide spectrum of cellular processes at multiple developmental stages. These include hematopoiesis, cell proliferation, homeotic gene regulation, histone exchange during DNA repair, and Notch signaling. To explore the wider gene network associated with Dom action, we used RNAi directed against domino (dom) to mediate loss-of-function at the wing margin, a tissue that is readily scored for phenotypic changes. Dom RNAi driven through GAL4-UAS elicited dominant wing nicking that responded phenotypically to the dose of dom and other loci known to function with dom. We screened for phenotypic modifiers of this wing phenotype among 2500 transpositions of the EP P element and found both enhancers and suppressors. Several classes of modifier were obtained, including those encoding transcription factors, RNA regulatory proteins, and factors that regulate cell growth, proliferation and autophagy, a lysosomal degradation pathway that affects cell growth under conditions of starvation and stress. Our analysis is consistent with prior studies, suggesting that Dom acts pleiotropically as a positive effector of Notch signaling and a repressor of proliferation. This genetic system should facilitate screens for additional loci associated with Dom function, and complement biochemical approaches to their regulatory activity.
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42
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Gehret AU, Hinkle PM. siRNA screen identifies the phosphatase acting on the G protein-coupled thyrotropin-releasing hormone receptor. ACS Chem Biol 2013; 8:588-98. [PMID: 23215350 DOI: 10.1021/cb3004513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
G protein-coupled receptors (GPCRs) are an ubiquitously expressed class of transmembrane proteins involved in the signal transduction of neurotransmitters, hormones and various other ligands. Their signaling output is desensitized by mechanisms involving phosphorylation, internalization, and dissociation from G proteins and resensitized by mechanisms involving dephosphorylation, but details about the phosphatases responsible are generally lacking. We describe here the use of an siRNA-based library to knock down expression of specific phosphatase subunits to identify protein phosphatase 1-α (PP1α) as important for the thyrotropin-releasing hormone (TRH) receptor. Inhibition of PP1α synthesis and overexpression of dominant negative PP1α preserved receptor phosphorylation under conditions favoring dephosphorylation, whereas overexpression of PP1α accelerated dephosphorylation. Knockdown of all three PP1 catalytic subunits inhibited TRH receptor phosphorylation much more powerfully than knockdown of PP1α alone, suggesting that different PP1 isoforms function redundantly. Knockdown of a structural subunit of PP2A, a second potential hit in the library screen, was ineffective. Calyculin A, a potent inhibitor of PP1 family phosphatases, strongly inhibited dephosphorylation of transfected TRH receptors and endogenous receptors in pituitary cells, but fostriecin, which is selective for PP2A family phosphatases, did not. We conclude that the PP1 class of phosphatases is essential for TRH receptor dephosphorylation.
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Affiliation(s)
- Austin U. Gehret
- Department of Science and Mathematics,
National Technical Institute for the Deaf, Rochester Institute of Technology, Rochester, New York 14623,
United States
| | - Patricia M. Hinkle
- Department
of Pharmacology and
Physiology, University of Rochester Medical Center, Rochester, New York 14642, United States
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Hedgehog signaling acts with the temporal cascade to promote neuroblast cell cycle exit. PLoS Biol 2013; 11:e1001494. [PMID: 23468593 PMCID: PMC3582610 DOI: 10.1371/journal.pbio.1001494] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 01/14/2013] [Indexed: 11/19/2022] Open
Abstract
During the development of the Drosophila nervous system, the developmentally regulated Hedgehog pathway, together with a series of temporal transcription factors, schedules the end of neurogenesis. In Drosophila postembryonic neuroblasts, transition in gene expression programs of a cascade of transcription factors (also known as the temporal series) acts together with the asymmetric division machinery to generate diverse neurons with distinct identities and regulate the end of neuroblast proliferation. However, the underlying mechanism of how this “temporal series” acts during development remains unclear. Here, we show that Hh signaling in the postembryonic brain is temporally regulated; excess (earlier onset of) Hh signaling causes premature neuroblast cell cycle exit and under-proliferation, whereas loss of Hh signaling causes delayed cell cycle exit and excess proliferation. Moreover, the Hh pathway functions downstream of Castor but upstream of Grainyhead, two components of the temporal series, to schedule neuroblast cell cycle exit. Interestingly, hh is likely a target of Castor. Hence, Hh signaling provides a link between the temporal series and the asymmetric division machinery in scheduling the end of neurogenesis. In almost all metazoans, neurons are produced by a group of neural stem cells/progenitors in a precise temporal manner, which is important for generating a functional nervous system. In Drosophila, this “timing” mechanism is mainly governed by the sequential switching of transcription factors in neural stem cells called neuroblasts, such that neuronal fate is associated with its birth order. These temporal factors also coordinate the termination of neuroblast division towards the end of neurogenesis. In this study, we show that Hedgehog (Hh) signaling also regulates the division rate of neuroblasts during their proliferative phase at larval stage, as well as the cessation of proliferation at early pupal stage. Excessive Hh signaling causes premature neuroblast cell cycle exit and early termination of neurogenesis, while loss of Hh signaling results in prolonged proliferation of neuroblasts beyond its physiological window. We also find that Hh signaling acts in concert with the temporal transcription factors, and is itself regulated by these factors. We hypothesize that this mode of interaction (temporal transcription factors with developmentally regulated signals like Hh) during neurogenesis could be widely conserved in other organisms.
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44
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Abstract
Hedgehog (Hh) signaling plays pivotal roles in embryonic development and adult tissue homeostasis, and its deregulation leads to numerous human disorders including cancer. Binding of Hh to Patched (Ptc), a twelve-transmembrane protein, alleviates its inhibition of Smoothened (Smo), a seven-transmembrane protein related to G-protein-coupled receptors (GPCRs), leading to Smo phosphorylation and activation. Smo acts through intracellular signaling complexes to convert the latent transcription factor Cubitus interruptus (Ci)/Gli from a truncated repressor to a full-length activator, leading to derepression/activation of Hh target genes. Increasing evidence suggests that phosphorylation participates in almost every step in the signal relay from Smo to Ci/Gli, and that differential phosphorylation of several key pathway components may be crucial for translating the Hh morphogen gradient into graded pathway activities. In this review, we focus on the multifaceted roles that phosphorylation plays in Hh signal transduction, and discuss the conservation and difference between Drosophila and mammalian Hh signaling mechanisms.
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45
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Kupinski AP, Raabe I, Michel M, Ail D, Brusch L, Weidemann T, Bökel C. Phosphorylation of the Smo tail is controlled by membrane localization and is dispensable for clustering. J Cell Sci 2013; 126:4684-97. [DOI: 10.1242/jcs.128926] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Hedgehog (Hh) signalling cascade is highly conserved and involved in development and disease throughout evolution. Nevertheless, in comparison with other pathways our mechanistic understanding of Hh signal transduction is remarkably incomplete. In the absence of ligand, the Hh receptor Patched (Ptc) represses the key signal transducer Smoothened (Smo) through an unknown mechanism. Hh binding to Ptc alleviates this repression, causing Smo redistribution to the plasma membrane, phosphorylation and opening of the Smo cytoplasmic tail, and Smo oligomerization. However, the order and interdependence of these events is as yet poorly understood. We have mathematically modelled and simulated Smo activation for two alternative modes of pathway activation, with Ptc primarily affecting either Smo localization or phosphorylation. Visualizing Smo activation through a novel, fluorescence based reporter allowed us to test these competing models. Here we show that Smo localization to the plasma membrane is sufficient for phosphorylation of the cytoplasmic tail in the presence of Ptc. Using fluorescence cross-correlation spectroscopy (FCCS) we furthermore demonstrate that inactivation of Ptc by Hh induces Smo clustering irrespective of Smo phosphorylation. Our observations therefore support a model of Hh signal transduction whereby Smo subcellular localization and not phosphorylation is the primary target of Ptc function.
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46
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WIP1 phosphatase modulates the Hedgehog signaling by enhancing GLI1 function. Oncogene 2012; 32:4737-47. [PMID: 23146903 DOI: 10.1038/onc.2012.502] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 09/10/2012] [Accepted: 09/18/2012] [Indexed: 02/06/2023]
Abstract
The Hedgehog-GLI (HH-GLI) signaling plays a critical role in controlling growth and tissue patterning during embryogenesis and is implicated in a variety of human malignancies, including those of the skin. Phosphorylation events have been shown to regulate the activity of the GLI transcription factors, the final effectors of the HH-GLI signaling pathway. Here, we show that WIP1 (or PPM1D), an oncogenic phosphatase amplified/overexpressed in several types of human cancer, is a positive modulator of the HH signaling. Mechanistically, WIP1 enhances the function of GLI1 by increasing its transcriptional activity, nuclear localization and protein stability, but not of GLI2 nor GLI3. We also find that WIP1 and GLI1 are in a complex. Modulation of the transcriptional activity of GLI1 by WIP1 depends on the latter's phosphatase activity and, remarkably, does not require p53, a known WIP1 target. Functionally, we find that WIP1 is required for melanoma and breast cancer cell proliferation and self-renewal in vitro and melanoma xenograft growth induced by activation of the HH signaling. Pharmacological blockade of the HH pathway with the SMOOTHENED antagonist cyclopamine acts synergistically with inhibition of WIP1 in reducing growth of melanoma and breast cancer cells in vitro. Overall, our data uncover a role for WIP1 in modulating the activity of GLI1 and in sustaining cancer cell growth and cancer stem cell self-renewal induced by activation of the HH pathway. These findings open a novel therapeutic approach for human melanomas and, possibly, other cancer types expressing WIP1 and with activated HH pathway.
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47
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Abstract
Hedgehog (Hh) proteins regulate the development of a wide range of metazoan embryonic and adult structures, and disruption of Hh signaling pathways results in various human diseases. Here, we provide a comprehensive review of the signaling pathways regulated by Hh, consolidating data from a diverse array of organisms in a variety of scientific disciplines. Similar to the elucidation of many other signaling pathways, our knowledge of Hh signaling developed in a sequential manner centered on its earliest discoveries. Thus, our knowledge of Hh signaling has for the most part focused on elucidating the mechanism by which Hh regulates the Gli family of transcription factors, the so-called "canonical" Hh signaling pathway. However, in the past few years, numerous studies have shown that Hh proteins can also signal through Gli-independent mechanisms collectively referred to as "noncanonical" signaling pathways. Noncanonical Hh signaling is itself subdivided into two distinct signaling modules: (i) those not requiring Smoothened (Smo) and (ii) those downstream of Smo that do not require Gli transcription factors. Thus, Hh signaling is now proposed to occur through a variety of distinct context-dependent signaling modules that have the ability to crosstalk with one another to form an interacting, dynamic Hh signaling network.
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Affiliation(s)
- David J Robbins
- Molecular Oncology Program, Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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48
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Wang N, Leung HT, Mazalouskas MD, Watkins GR, Gomez RJ, Wadzinski BE. Essential roles of the Tap42-regulated protein phosphatase 2A (PP2A) family in wing imaginal disc development of Drosophila melanogaster. PLoS One 2012; 7:e38569. [PMID: 22701670 PMCID: PMC3368869 DOI: 10.1371/journal.pone.0038569] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 05/07/2012] [Indexed: 11/18/2022] Open
Abstract
Protein ser/thr phosphatase 2A family members (PP2A, PP4, and PP6) are implicated in the control of numerous biological processes, but our understanding of the in vivo function and regulation of these enzymes is limited. In this study, we investigated the role of Tap42, a common regulatory subunit for all three PP2A family members, in the development of Drosophila melanogaster wing imaginal discs. RNAi-mediated silencing of Tap42 using the binary Gal4/UAS system and two disc drivers, pnr- and ap-Gal4, not only decreased survival rates but also hampered the development of wing discs, resulting in a remarkable thorax cleft and defective wings in adults. Silencing of Tap42 also altered multiple signaling pathways (HH, JNK and DPP) and triggered apoptosis in wing imaginal discs. The Tap42RNAi-induced defects were the direct result of loss of regulation of Drosophila PP2A family members (MTS, PP4, and PPV), as enforced expression of wild type Tap42, but not a phosphatase binding defective Tap42 mutant, rescued fly survivorship and defects. The experimental platform described herein identifies crucial roles for Tap42•phosphatase complexes in governing imaginal disc and fly development.
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Affiliation(s)
- Ning Wang
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Hung-Tat Leung
- Department of Biological Sciences, Grambling State University, Grambling, Louisiana, United States of America
| | - Matthew D. Mazalouskas
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Guy R. Watkins
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Rey J. Gomez
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Brian E. Wadzinski
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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49
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Protein Phosphatase 4 Cooperates with Smads to Promote BMP Signaling in Dorsoventral Patterning of Zebrafish Embryos. Dev Cell 2012; 22:1065-78. [DOI: 10.1016/j.devcel.2012.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 12/29/2011] [Accepted: 03/03/2012] [Indexed: 11/21/2022]
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50
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Hh-induced Smoothened conformational switch is mediated by differential phosphorylation at its C-terminal tail in a dose- and position-dependent manner. Dev Biol 2012; 366:172-84. [PMID: 22537496 DOI: 10.1016/j.ydbio.2012.04.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 04/02/2012] [Accepted: 04/07/2012] [Indexed: 12/26/2022]
Abstract
The activation of Smoothened (Smo) requires phosphorylation at three clusters of Serine residues in Drosophila Hedgehog (Hh) signaling. However, the mechanism by which phosphorylation promotes Smo conformational change and subsequently activates Smo in response to Hh gradient remains unclear. Here, we show that the conformational states of Smo are determined by not only the amount but also the position of the negative charges provided by phosphorylation. By using a Smo phospho-specific antibody, we demonstrate that Smo is differentially phosphorylated at three clusters of serine residues in response to levels of Hh activity. Mutating the first cluster, compared to mutating the other clusters, impairs Smo activity more severely, whereas mutating the last cluster prohibits C-terminus dimerization. In addition, phosphorylation of the membrane proximal cluster promotes phosphorylation of the distal cluster. We propose a zipper-lock model in which the gradual phosphorylation at these clusters induces a gradual conformational change in the Smo cytoplasmic tail, which promotes the interaction between Smo and Costal2 (Cos2). Moreover, we show that Hh regulates both PKA and CK1 phosphorylation of Smo. Thus, the differential phosphorylation of Smo mediates the thresholds of Hh activity.
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