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Black JA, Klinger CM, Lemgruber L, Dacks JB, Mottram JC, McCulloch R. AAK1-like: A putative pseudokinase with potential roles in cargo uptake in bloodstream form Trypanosoma brucei parasites. J Eukaryot Microbiol 2023; 70:e12994. [PMID: 37548427 PMCID: PMC10952953 DOI: 10.1111/jeu.12994] [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: 01/30/2023] [Revised: 07/21/2023] [Accepted: 07/21/2023] [Indexed: 08/08/2023]
Abstract
Selection and internalization of cargo via clathrin-mediated endocytosis requires adaptor protein complexes. One complex, AP-2, acts during cargo selection at the plasma membrane. African trypanosomes lack all components of the AP-2 complex, except for a recently identified orthologue of the AP-2-associated protein kinase 1, AAK1. In characterized eukaryotes, AAK1 phosphorylates the μ2 subunit of the AP-2 complex to enhance cargo recognition and uptake into clathrin-coated vesicles. Here, we show that kinetoplastids encode not one, but two AAK1 orthologues: one (AAK1L2) is absent from salivarian trypanosomes, while the other (AAK1L1) lacks important kinase-specific residues in a range of trypanosomes. These AAK1L1 and AAK1L2 novelties reinforce suggestions of functional divergence in endocytic uptake within salivarian trypanosomes. Despite this, we show that AAK1L1 null mutant Trypanosoma brucei, while viable, display slowed proliferation, morphological abnormalities including swelling of the flagellar pocket, and altered cargo uptake. In summary, our data suggest an unconventional role for a putative pseudokinase during endocytosis and/or vesicular trafficking in T. brucei, independent of AP-2.
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Affiliation(s)
- Jennifer A. Black
- The Wellcome Centre for Integrative Parasitology, School of Infection & ImmunityUniversity of GlasgowGlasgowUK
- Department of Cell and Molecular Biology, Ribeirão Preto Medical SchoolUniversity of São PauloSão PauloBrazil
| | - Christen M. Klinger
- The Wellcome Centre for Integrative Parasitology, School of Infection & ImmunityUniversity of GlasgowGlasgowUK
- Division of Infectious Diseases, Department of Medicine, Li Ka Shing Centre for Health, Research InnovationUniversity of AlbertaEdmontonAlbertaCanada
| | - Leandro Lemgruber
- The Wellcome Centre for Integrative Parasitology, School of Infection & ImmunityUniversity of GlasgowGlasgowUK
- Glasgow Imaging Facility, School of Infection & ImmunityUniversity of GlasgowGlasgowUK
| | - Joel B. Dacks
- Department of Cell and Molecular Biology, Ribeirão Preto Medical SchoolUniversity of São PauloSão PauloBrazil
- Institute of Parasitology, Biology CentreCzech Academy of SciencesCeske Budejovice (Budweis)Czech Republic
| | - Jeremy C. Mottram
- York Biomedical Research Institute and Department of BiologyUniversity of YorkYorkUK
| | - Richard McCulloch
- The Wellcome Centre for Integrative Parasitology, School of Infection & ImmunityUniversity of GlasgowGlasgowUK
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2
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van der Velden LM, Maas P, van Amersfoort M, Timmermans-Sprang EPM, Mensinga A, van der Vaart E, Malergue F, Viëtor H, Derksen PWB, Klumperman J, van Agthoven A, Egan DA, Mol JA, Strous GJ. Small molecules to regulate the GH/IGF1 axis by inhibiting the growth hormone receptor synthesis. Front Endocrinol (Lausanne) 2022; 13:926210. [PMID: 35966052 PMCID: PMC9365994 DOI: 10.3389/fendo.2022.926210] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Growth hormone (GH) and insulin-like growth factor-1 (IGF1) play an important role in mammalian development, cell proliferation and lifespan. Especially in cases of tumor growth there is an urgent need to control the GH/IGF1 axis. In this study we screened a 38,480-compound library, and in two consecutive rounds of analogues selection, we identified active lead compounds based on the following criteria: inhibition the GH receptor (GHR) activity and its downstream effectors Jak2 and STAT5, and inhibition of growth of breast and colon cancer cells. The most active small molecule (BM001) inhibited both the GH/IGF1 axis and cell proliferation with an IC50 of 10-30 nM of human cancer cells. BM001 depleted GHR in human lymphoblasts. In preclinical xenografted experiments, BM001 showed a strong decrease in tumor volume in mice transplanted with MDA-MB-231 breast cancer cells. Mechanistically, the drug acts on the synthesis of the GHR. Our findings open the possibility to inhibit the GH/IGF1 axis with a small molecule.
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Affiliation(s)
- Lieke M. van der Velden
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Peter Maas
- Specs Compound Handling, Zoetermeer, Netherlands
- *Correspondence: Ger J. Strous, ; Jan A. Mol, ; Peter Maas,
| | | | | | - Anneloes Mensinga
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Elisabeth van der Vaart
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Fabrice Malergue
- Department of Research and Development, Beckman Coulter Life Science, Immunotech Marseille, Marseille, France
| | - Henk Viëtor
- Drug Discovery Factory (DDF) Ventures, Breukelen, Netherlands
| | - Patrick W B. Derksen
- Department of Pathology, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Judith Klumperman
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Andreas van Agthoven
- Department of Research and Development, Beckman Coulter Life Science, Immunotech Marseille, Marseille, France
| | - David A. Egan
- Cell Screening Core, Department of Cell Biology, Center for Molecular Medicine, University Medical Center, Utrecht, Netherlands
| | - Jan A. Mol
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
- *Correspondence: Ger J. Strous, ; Jan A. Mol, ; Peter Maas,
| | - Ger J. Strous
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
- *Correspondence: Ger J. Strous, ; Jan A. Mol, ; Peter Maas,
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Chhabra Y, Lee CMM, Müller AF, Brooks AJ. GHR signalling: Receptor activation and degradation mechanisms. Mol Cell Endocrinol 2021; 520:111075. [PMID: 33181235 DOI: 10.1016/j.mce.2020.111075] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/01/2020] [Accepted: 11/03/2020] [Indexed: 12/21/2022]
Abstract
Growth hormone (GH) actions via initiating cell signalling through the GH receptor (GHR) are important for many physiological processes, in addition to its well-known role in regulating growth. The activation of JAK-STAT signalling by GH is well characterized, however knowledge on GH activation of SRC family kinases (SFKs) is still limited. In this review we summarise the collective knowledge on the activation, regulation, and downstream signalling of GHR. We highlight studies on GH activation of SFKs and the important outcome of this signalling pathway with a focus on the different degradation mechanisms that can regulate GHR availability since this is an area that warrants further study considering its role in tumour progression.
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Affiliation(s)
- Yash Chhabra
- The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, QLD, 4102, Australia; Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21231, USA
| | - Christine M M Lee
- The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, QLD, 4102, Australia
| | - Alexandra Franziska Müller
- The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, QLD, 4102, Australia
| | - Andrew J Brooks
- The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, QLD, 4102, Australia.
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Strous GJ, Almeida ADS, Putters J, Schantl J, Sedek M, Slotman JA, Nespital T, Hassink GC, Mol JA. Growth Hormone Receptor Regulation in Cancer and Chronic Diseases. Front Endocrinol (Lausanne) 2020; 11:597573. [PMID: 33312162 PMCID: PMC7708378 DOI: 10.3389/fendo.2020.597573] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/14/2020] [Indexed: 12/14/2022] Open
Abstract
The GHR signaling pathway plays important roles in growth, metabolism, cell cycle control, immunity, homeostatic processes, and chemoresistance via both the JAK/STAT and the SRC pathways. Dysregulation of GHR signaling is associated with various diseases and chronic conditions such as acromegaly, cancer, aging, metabolic disease, fibroses, inflammation and autoimmunity. Numerous studies entailing the GHR signaling pathway have been conducted for various cancers. Diverse factors mediate the up- or down-regulation of GHR signaling through post-translational modifications. Of the numerous modifications, ubiquitination and deubiquitination are prominent events. Ubiquitination by E3 ligase attaches ubiquitins to target proteins and induces proteasomal degradation or starts the sequence of events that leads to endocytosis and lysosomal degradation. In this review, we discuss the role of first line effectors that act directly on the GHR at the cell surface including ADAM17, JAK2, SRC family member Lyn, Ubc13/CHIP, proteasome, βTrCP, CK2, STAT5b, and SOCS2. Activity of all, except JAK2, Lyn and STAT5b, counteract GHR signaling. Loss of their function increases the GH-induced signaling in favor of aging and certain chronic diseases, exemplified by increased lung cancer risk in case of a mutation in the SOCS2-GHR interaction site. Insight in their roles in GHR signaling can be applied for cancer and other therapeutic strategies.
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Affiliation(s)
- Ger J. Strous
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
- BIMINI Biotech B.V., Leiden, Netherlands
| | - Ana Da Silva Almeida
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Joyce Putters
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Julia Schantl
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Magdalena Sedek
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Johan A. Slotman
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Tobias Nespital
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Gerco C. Hassink
- Department of Cell Biology, Centre for Molecular Medicine, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Jan A. Mol
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
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5
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Ruxolitinib sensitizes ovarian cancer to reduced dose Taxol, limits tumor growth and improves survival in immune competent mice. Oncotarget 2017; 8:94040-94053. [PMID: 29212208 PMCID: PMC5706854 DOI: 10.18632/oncotarget.21541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/02/2017] [Indexed: 12/15/2022] Open
Abstract
Background Chemotherapy initially reduces the tumor burden in patients with ovarian cancer. However, tumors recur in over 70% of patients, creating the need for novel therapeutic approaches. Methods We evaluated Ruxolitinib, an FDA-approved JAK 1/2 kinase inhibitor, as a potential adjunctive therapy for use with low-dose Taxol (Paclitaxel) by assessing the impact on in vitro proliferation and colony formation of ID8 cells or human TOV-112D ovarian cancer cells, as well as flow cytometric measurement of surface markers associated with cellular stress and stemness by ID8 cells. The syngeneic ID8 murine model of ovarian cancer was used to assess the impact of Ruxolitinib and Taxol, individually and in combination, on tumor initiation and growth, as well as capacity to extend survival. Results Ruxolitinib (≤10 μM) sensitized both ID8 and TOV-112D cells to low concentrations of Taxol (≤5 nM), limiting cell proliferation and colony formation in vitro. Mechanistically, we demonstrated that Taxol induced expression of stress and stemness markers including GRP78 and CD133 was significantly reduced by addition of Ruxolitinib. Finally, we demonstrated that a single administration of a low-dose of Taxol (10 mg/Kg) together with daily Ruxolitinib (30 mg/Kg; which is equivalent to plasma concentrations of ∼ 0.01 μM steady-state) limited ID8 tumor growth in vivo and significantly extended median survival up to 53.5% (median 70 v 107.5 days) as compared to control mice. Conclusion Together, these data support the use of Ruxolitinib in combination with low-dose Taxol as a therapeutic approach with the potential for improved efficacy and reduced side effects for patients with recurrent ovarian cancer.
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Chen PH, Yao H, Huang LJS. Cytokine Receptor Endocytosis: New Kinase Activity-Dependent and -Independent Roles of PI3K. Front Endocrinol (Lausanne) 2017; 8:78. [PMID: 28507533 PMCID: PMC5410625 DOI: 10.3389/fendo.2017.00078] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/30/2017] [Indexed: 12/14/2022] Open
Abstract
Type I and II cytokine receptors are cell surface sensors that bind cytokines in the extracellular environment and initiate intracellular signaling to control processes such as hematopoiesis, immune function, and cellular growth and development. One key mechanism that regulates signaling from cytokine receptors is through receptor endocytosis. In this mini-review, we describe recent advances in endocytic regulations of cytokine receptors, focusing on new paradigms by which PI3K controls receptor endocytosis through both kinase activity-dependent and -independent mechanisms. These advances underscore the notion that the p85 regulatory subunit of PI3K has functions beyond regulating PI3K kinase activity, and that PI3K plays both positive and negative roles in receptor signaling. On the one hand, the PI3K/Akt pathway controls various aspects downstream of cytokine receptors. On the other hand, it stimulates receptor endocytosis and downregulation, thus contributing to signaling attenuation.
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Affiliation(s)
- Ping-hung Chen
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Huiyu Yao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Lily Jun-shen Huang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- *Correspondence: Lily Jun-shen Huang,
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7
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Nespital T, van der Velden LM, Mensinga A, van der Vaart ED, Strous GJ. Fos-Zippered GH Receptor Cytosolic Tails Act as Jak2 Substrates and Signal Transducers. Mol Endocrinol 2016; 30:290-301. [PMID: 26859362 DOI: 10.1210/me.2015-1315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Members of the Janus kinase (Jak) family initiate the majority of downstream signaling events of the cytokine receptor family. The prevailing principle is that the receptors act in dimers: 2 Jak2 molecules bind to the cytosolic tails of a cytokine receptor family member and initiate Jak-signal transducer and activator of transcription signaling upon a conformational change in the receptor complex, induced by the cognate cytokine. Due to the complexity of signaling complexes, there is a strong need for in vitro model systems. To investigate the molecular details of the Jak2 interaction with the GH receptor (GHR), we used cytosolic tails provided with leucine zippers derived from c-Fos to mimic the dimerized state of GHR. Expressed together with Jak2, fos-zippered tails, but not unzippered tails, were stabilized. In addition, the Jak-signal transducer and activator of transcription signaling pathway was activated by the fos-zippered tails. The stabilization depended also on α-helix rotation of the zippers. Fos-zippered GHR tails and Jak2, both purified from baculovirus-infected insect cells, interacted via box1 with a binding affinity of approximately 40nM. As expected, the Jak kinase inhibitor Ruxolitinib inhibited the stabilization but did not affect the c-Fos-zippered GHR tail-Jak2 interaction. Analysis by blue-native gel electrophoresis revealed high molecular-weight complexes containing both Jak2 and nonphosphorylated GHR tails, whereas Jak2-dissociated tails were highly phosphorylated and monomeric, implying that Jak2 detaches from its substrate upon phosphorylation.
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Affiliation(s)
- Tobias Nespital
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Lieke M van der Velden
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Anneloes Mensinga
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Elisabeth D van der Vaart
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Ger J Strous
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
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8
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Tagirov M, Golovan S. Sexual dimorphism in the early embryogenesis of the chicken (Gallus Gallus domesticus). Mol Reprod Dev 2015; 82:332-43. [DOI: 10.1002/mrd.22476] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 02/22/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Makhsud Tagirov
- Poultry Research Institute; Ukrainian Academy of Agrarian Sciences; Borky; Zmiiv District Kharkiv Region Ukraine
| | - Serguei Golovan
- Department of Animal and Food Science; University of Delaware; Newark Delaware
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9
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Tagirov M, Rutkowska J. Sexual Dimorphism in the Early Embryogenesis in Zebra Finches. PLoS One 2014; 9:e114625. [PMID: 25493645 PMCID: PMC4262425 DOI: 10.1371/journal.pone.0114625] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 11/12/2014] [Indexed: 01/06/2023] Open
Abstract
Sex-specific gene expression before the onset of gonadogensis has been documented in embryos of mammals and chickens. In several mammalian species, differences in gene expression are accompanied by faster growth of pre-implantation male embryos. Here we asked whether avian embryos before gonadal differentiation are also sex-dimorphic in size and what genes regulate their growth. We used captive zebra finches (Taeniopygia guttata) whose freshly laid eggs were artificially incubated for 36–40 hours. Analyses controlling for the exact time of incubation of 81 embryos revealed that males were larger than females in terms of Hamburger and Hamilton stage and number of somites. Expression of 15 genes involved in cell cycle regulation, growth, metabolic activity, steroidogenic pathway and stress modulation were measured using RT-PCR in 5 male and 5 female embryos incubated for exactly 36 h. We found that in the presence of equal levels of the growth hormone itself, the faster growth of male embryos is most likely achieved by the overexpression of the growth hormone receptor gene and three other genes responsible for cell cycle regulation and metabolism, all of them located on the Z chromosome. Autosomal genes did not show sex-specific expression, except for the steroidogenic factor 1 which was expressed only in female embryos. To our knowledge this is the first report of sexual size dimorphism before gonadogenesis in birds. The finding suggests that faster growth of early male embryos is conserved through the mammalian and bird phyla, irrespective of their differential sex chromosome systems.
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Affiliation(s)
- Makhsud Tagirov
- Poultry Research Institute, Ukrainian Academy of Agrarian Sciences, Borky, Ukraine
| | - Joanna Rutkowska
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
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10
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Malergue F, van Agthoven A, Scifo C, Egan D, Strous GJ. Automation of a Phospho-STAT5 Staining Procedure for Flow Cytometry for Application in Drug Discovery. ACTA ACUST UNITED AC 2014; 20:416-21. [DOI: 10.1177/1087057114555477] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Drug discovery often requires the screening of compound libraries on tissue cultured cells. Some major targets in drug discovery belong to signal transduction pathways, and PerFix EXPOSE* allows easy flow cytometry phospho assays. We thus investigated the possibility to further simplify and automate this assay, to allow the direct screening of drugs targeting signaling pathways. We show here the sensitivity of this fully automated assay on human growth hormone (hGH)-driven JAK/STAT5-activated IM-9 cells, and we discuss the throughput of this system, which is compatible with medium-throughput drug screening. Because the kit works directly on whole blood samples, ex-vivo assays are also possible with this approach, which could allow for the screening of drugs under more physiological conditions.
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Affiliation(s)
- Fabrice Malergue
- Beckman Coulter Life Science, Inc., Global Assay and Applications Development, Marseille, France
| | - Andreas van Agthoven
- Beckman Coulter Life Science, Inc., Global Assay and Applications Development, Marseille, France
| | - Caroline Scifo
- Beckman Coulter Life Science, Inc., Global Assay and Applications Development, Marseille, France
| | - Dave Egan
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ger J. Strous
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
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11
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Carbone CJ, Fuchs SY. Eliminative signaling by Janus kinases: role in the downregulation of associated receptors. J Cell Biochem 2014; 115:8-16. [PMID: 23959845 DOI: 10.1002/jcb.24647] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 07/31/2013] [Indexed: 12/11/2022]
Abstract
Activation of cytokine receptor-associated Janus kinases (JAKs) mediates most, if not all, of the cellular responses to peptide hormones and cytokines. Consequently, JAKs play a paramount role in homeostasis and immunity. Members of this family of tyrosine kinases control the cytokine/hormone-induced alterations in cell gene expression program. This function is largely mediated through an ability to signal toward activation of the signal transducer and activator of transcription proteins (STAT), as well as toward some other pathways. Importantly, JAKs are also instrumental in tightly controlling the expression of associated cytokine and hormone receptors, and, accordingly, in regulating the cell sensitivity to these cytokines and hormones. This review highlights the enzymatic and non-enzymatic mechanisms of this regulation and discusses the importance of the ambidextrous nature of JAK as a key signaling node that integrates the combining functions of forward signaling and eliminative signaling. Attention to the latter aspect of JAK function may contribute to emancipating our approaches to the pharmacological modulation of JAKs.
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Affiliation(s)
- Christopher J Carbone
- Department of Animal Biology and Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104
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12
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Sedek M, van der Velden LM, Strous GJ. Multimeric growth hormone receptor complexes serve as signaling platforms. J Biol Chem 2013; 289:65-73. [PMID: 24280222 DOI: 10.1074/jbc.m113.523373] [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: 11/06/2022] Open
Abstract
Growth hormone (GH) signaling is required for promoting longitudinal body growth, stem cell activation, differentiation, and survival and for regulation of metabolism. Failure to adequately regulate GH signaling leads to disease: excessive GH signaling has been connected to cancer, and GH insensitivity has been reported in cachexia patients. Since its discovery in 1989, the receptor has served a pivotal role as the prototype cytokine receptor both structurally and functionally. Phosphorylation and ubiquitylation regulate the GH receptor (GHR) at the cell surface: two ubiquitin ligases (SCF(βTrCP2) and CHIP) determine the GH responsiveness of cells by controlling its endocytosis, whereas JAK2 initiates the JAK/STAT pathway. We used blue native electrophoresis to identify phosphorylated and ubiquitylated receptor intermediates. We show that GHRs occur as ∼500-kDa complexes that dimerize into active ∼900-kDa complexes upon GH binding. The dimerized complexes act as platforms for transient interaction with JAK2 and ubiquitin ligases. If GH and receptors are made in the same cell (autocrine mode), only limited numbers of ∼900-kDa complexes are formed. The experiments reveal the dynamic changes in post-translational modifications during GH-induced signaling events and show that relatively simple cytokine receptors like GHRs are able to form higher order protein complexes. Insight in the complex formation of cytokine receptors is crucially important for engineering cytokines that control ligand-induced cell responses and for generating a new class of therapeutic agents for a wide range of diseases.
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Affiliation(s)
- Magdalena Sedek
- From the Department of Cell Biology and Institute of Biomembranes, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
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13
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βTrCP interacts with the ubiquitin-dependent endocytosis motif of the GH receptor in an unconventional manner. Biochem J 2013; 453:291-301. [PMID: 23607312 DOI: 10.1042/bj20121843] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
GH (growth hormone) binding to the GHR (GH receptor) triggers essential signalling pathways that promote growth and metabolic regulation. The sensitivity of the cells to GH is mainly controlled by the endocytosis of the receptor via βTrCP (β-transducin repeat-containing protein). In the present study, we show that βTrCP interacts directly via its WD40 domain with the UbE (ubiquitin-dependent endocytosis) motif in GHR, promoting GHR ubiquitination in vitro. NMR experiments demonstrated that the UbE motif is essentially unstructured, and, together with functional mapping of the UbE and βTrCP WD40 residues necessary for binding, led to a unique interaction model of βTrCP with GHR-UbE. This interaction is different from the conventional βTrCP-substrate interactions described to date. This interaction therefore represents a promising specific target to develop drugs that inhibit GHR endocytosis and increase GH sensitivity in cachexia patients.
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14
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SUMOylation is a regulator of the translocation of Jak2 between nucleus and cytosol. Biochem J 2013; 453:231-9. [DOI: 10.1042/bj20121375] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Jak2 (Janus kinase 2) initiates the signal transduction of many cytokine receptors. We discovered that Jak2 is SUMOylated on multiple lysine residues by SUMO2/3 (small ubiquitin-related modifier 2/3) chains. Analysis of Jak2 mutants revealed that Jak2 SUMOylation depends on the presence of an active catalytic site. We used the GH (growth hormone) receptor to study the physiological relevance of Jak2 SUMOylation. Both GH stimulation and several other environmental stressors increased Jak2 SUMOylation. Cell fractionation showed that SUMOylated Jak2 is mainly present in the nucleus. The constitutively active V617F Jak2 mutant, implicated in myeloproliferative diseases, was highly SUMOylated in the absence of stimuli. These data provide evidence that Jak2 SUMOylation controls Jak2 shuttling between cytoplasm and nucleus.
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15
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The ING1a tumor suppressor regulates endocytosis to induce cellular senescence via the Rb-E2F pathway. PLoS Biol 2013; 11:e1001502. [PMID: 23472054 PMCID: PMC3589274 DOI: 10.1371/journal.pbio.1001502] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 01/24/2013] [Indexed: 02/07/2023] Open
Abstract
An age-associated isoform of ING1, ING1a, induces cell senescence by altering endocytosis, subsequently activating the retinoblastoma tumor suppressor. The INhibitor of Growth (ING) proteins act as type II tumor suppressors and epigenetic regulators, being stoichiometric members of histone acetyltransferase and histone deacetylase complexes. Expression of the alternatively spliced ING1a tumor suppressor increases >10-fold during replicative senescence. ING1a overexpression inhibits growth; induces a large flattened cell morphology and the expression of senescence-associated β-galactosidase; increases Rb, p16, and cyclin D1 levels; and results in the accumulation of senescence-associated heterochromatic foci. Here we identify ING1a-regulated genes and find that ING1a induces the expression of a disproportionate number of genes whose products encode proteins involved in endocytosis. Intersectin 2 (ITSN2) is most affected by ING1a, being rapidly induced >25-fold. Overexpression of ITSN2 independently induces expression of the p16 and p57KIP2 cyclin-dependent kinase inhibitors, which act to block Rb inactivation, acting as downstream effectors of ING1a. ITSN2 is also induced in normally senescing cells, consistent with elevated levels of ING1a inducing ITSN2 as part of a normal senescence program. Inhibition of endocytosis or altering the stoichiometry of endosome components such as Rab family members similarly induces senescence. Knockdown of ITSN2 also blocks the ability of ING1a to induce a senescent phenotype, confirming that ITSN2 is a major transducer of ING1a-induced senescence signaling. These data identify a pathway by which ING1a induces senescence and indicate that altered endocytosis activates the Rb pathway, subsequently effecting a senescent phenotype. Alternative splicing of several genes including the p16 and p53 tumor suppressors has been reported to increase during replicative senescence of normal diploid cells, but the biological functions of most alternative transcripts are unknown. We have found that a splicing product of the ING1 epigenetic regulator, ING1a, also increases during senescence; moreover, forced expression of ING1a at these levels in otherwise growth-competent cells can induce senescence. In this study we have determined that a major mechanism by which ING1a induces senescence is through inhibiting endocytosis; this subsequently activates the retinoblastoma (Rb) tumor suppressor pathway by increasing Rb levels and preventing its inactivation through multiple mechanisms. Our study also establishes a link between endocytosis and oxidative stress and suggests that multiple mechanisms that induce cellular senescence may do so by inhibiting normal endocytic processes, thereby affecting normal signal transduction pathways including those mitogenic pathways required for cell growth.
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Nespital T, Strous GJ. The Jak/STAT signaling pathway is downregulated at febrile temperatures. PLoS One 2012; 7:e49374. [PMID: 23166650 PMCID: PMC3498154 DOI: 10.1371/journal.pone.0049374] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 10/08/2012] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The Janus family of kinases (JAKs), Jak1, Jak2, Jak3, and Tyk2, constitute a subgroup of non-receptor protein tyrosine kinases. Upon cytokine binding, the receptor-associated kinases are activated and phosphorylate tyrosine residues in their cognate cytokine receptors. Their activities are controlled at several levels and include cellular concentration, auto-activation, and degradation. PRINCIPAL FINDINGS Our findings show that elevated temperatures in the fever range irreversibly aggregate Jak2 and considerably reduce functional Jak2 protein levels. Jak2 synthesis remains unaltered. We observed that also the protein level of the signal transducer and activator of transcription, STAT5b, is transiently decreased at temperatures above 37°C. Consequently, the signaling response, e.g. via the growth hormone receptor, is reduced. CONCLUSIONS/SIGNIFICANCE These findings predict that elevated body temperatures lower the responsiveness of cytokine receptors.
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Affiliation(s)
| | - Ger J. Strous
- Department of Cell Biology and Institute of Biomembranes, University Medical Center Utrecht, Utrecht, The Netherlands
- * E-mail:
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Deng L, Jiang J, Frank SJ. Growth hormone-induced JAK2 signaling and GH receptor down-regulation: role of GH receptor intracellular domain tyrosine residues. Endocrinology 2012; 153:2311-22. [PMID: 22416081 PMCID: PMC3339656 DOI: 10.1210/en.2011-1452] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GH receptor (GHR) mediates important somatogenic and metabolic effects of GH. A thorough understanding of GH action requires intimate knowledge of GHR activation mechanisms, as well as determinants of GH-induced receptor down-regulation. We previously demonstrated that a GHR mutant in which all intracellular tyrosine residues were changed to phenylalanine was defective in its ability to activate signal transducer and activator of transcription (STAT)5 and deficient in GH-induced down-regulation, but able to allow GH-induced Janus family of tyrosine kinase 2 (JAK2) activation. We now further characterize the signaling and trafficking characteristics of this receptor mutant. We find that the mutant receptor's extracellular domain conformation and its interaction with GH are indistinguishable from the wild-type receptor. Yet the mutant differs greatly from the wild-type in that GH-induced JAK2 activation is augmented and far more persistent in cells bearing the mutant receptor. Notably, unlike STAT5 tyrosine phosphorylation, GH-induced STAT1 tyrosine phosphorylation is retained and augmented in mutant GHR-expressing cells. The defective receptor down-regulation and persistent JAK2 activation of the mutant receptor do not depend on the sustained presence of GH or on the cell's ability to carry out new protein synthesis. Mutant receptors that exhibit resistance to GH-induced down-regulation are enriched in the disulfide-linked form of the receptor, which reflects the receptor's activated conformation. Furthermore, acute GH-induced internalization, a proximal step in down-regulation, is markedly impaired in the mutant receptor compared to the wild-type receptor. These findings are discussed in the context of determinants and mechanisms of regulation of GHR down-regulation.
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Affiliation(s)
- Luqin Deng
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, 1530 3 Avenue South, Birmingham, Alabama 35294-0012, USA
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Li B, Zhang G, Li C, He D, Li X, Zhang C, Tang F, Deng X, Lu J, Tang Y, Li R, Chen Z, Duan C. Identification of JAK2 as a mediator of FIP1L1-PDGFRA-induced eosinophil growth and function in CEL. PLoS One 2012; 7:e34912. [PMID: 22523564 PMCID: PMC3327703 DOI: 10.1371/journal.pone.0034912] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 03/08/2012] [Indexed: 12/23/2022] Open
Abstract
The Fip1-like1 (FIP1L1)-platelet-derived growth factor receptor alpha fusion gene (F/P) arising in the pluripotent hematopoietic stem cell (HSC),causes 14% to 60% of patients with hypereosinophilia syndrome (HES). These patients, classified as having F/P (+) chronic eosinophilic leukemia (CEL), present with clonal eosinophilia and display a more aggressive disease phenotype than patients with F/P (–) HES patients. The mechanisms underlying predominant eosinophil lineage targeting and the cytotoxicity of eosinophils in this leukemia remain unclear. Given that the Janus tyrosine kinase (JAK)/signal transducers and activators of transcription (Stat) signaling pathway is key to cytokine receptor-mediated eosinophil development and activated Stat3 and Stat5 regulate the expression of genes involved in F/P malignant transformation, we investigated whether and how JAK proteins were involved in the pathogenesis of F/P-induced CEL. F/P activation of JAK2, Stat3 and Stat5, were confirmed in all the 11 F/P (+) CEL patients examined. In vitro inhibition of JAK2 in EOL-1, primary F/P(+) CEL cells (PC) and T674I F/P Imatinib resistant cells(IR) by either JAK2-specific short interfering RNA (siRNA) or the tryphostin derivative AG490(AG490), significantly reduced cellular proliferation and induced cellular apoptosis. The F/P can enhance the IL-5-induced JAK2 activation, and further results indicated that JAK2 inhibition blocked IL-5-induced cellular migration and activation of the EOL-1 and PC cells in vitro. F/P-stimulation of the JAK2 suppressed cells led to a significantly reduction in Stat3 activation, but relatively normal induction of Stat5 activation. Interestingly, JAK2 inhibition also reduced PI3K, Akt and NF-κB activity in a dose-dependent manner, and suppressed expression levels of c-Myc and Survivin. These results strongly suggest that JAK2 is activated by F/P and is required for F/P stimulation of cellular proliferation and infiltration, possibly through induction of c-Myc and Survivin expression via activation of multiple signaling pathways, including NF-κB, Stat3, and PI3K/Akt.
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Affiliation(s)
- Bin Li
- Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, People's Republic of China
- Division of Hematology, Institute of Molecular Hematology, the Second Xiang Ya Hospital, Central South University, Changsha City, Hunan, People's Republic of China
- Division of Oncology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Guangsen Zhang
- Division of Hematology, Institute of Molecular Hematology, the Second Xiang Ya Hospital, Central South University, Changsha City, Hunan, People's Republic of China
| | - Cui Li
- Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Dan He
- Medical Research Center, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Xinying Li
- Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Chunfang Zhang
- Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Faqing Tang
- Clinical Laboratory, Zhuhai Hospital, Jinan University, Zhuhai, People's Republic of China
| | - Xiyun Deng
- Department of Surgery, the University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Jingchen Lu
- Division of Oncology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Youhong Tang
- Division of Oncology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Ruijuan Li
- Division of Hematology, Institute of Molecular Hematology, the Second Xiang Ya Hospital, Central South University, Changsha City, Hunan, People's Republic of China
| | - Zhuchu Chen
- Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Chaojun Duan
- Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, People's Republic of China
- Medical Research Center, Xiangya Hospital, Central South University, Changsha, People's Republic of China
- * E-mail:
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Slotman JA, da Silva Almeida AC, Hassink GC, van de Ven RHA, van Kerkhof P, Kuiken HJ, Strous GJ. Ubc13 and COOH terminus of Hsp70-interacting protein (CHIP) are required for growth hormone receptor endocytosis. J Biol Chem 2012; 287:15533-43. [PMID: 22433856 DOI: 10.1074/jbc.m111.302521] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Growth hormone receptor (GHR) endocytosis is a highly regulated process that depends on the binding and activity of the multimeric ubiquitin ligase, SCF(βTrCP) (Skp Cullin F-box). Despite a specific interaction between β-transducin repeat-containing protein (βTrCP) and the GHR, and a strict requirement for ubiquitination activity, the receptor is not an obligatory target for SCF(βTrCP)-directed Lys(48) polyubiquitination. We now show that also Lys(63)-linked ubiquitin chain formation is required for GHR endocytosis. We identified both the ubiquitin-conjugating enzyme Ubc13 and the ubiquitin ligase COOH terminus of Hsp70 interacting protein (CHIP) as being connected to this process. Ubc13 activity and its interaction with CHIP precede endocytosis of GHR. In addition to βTrCP, CHIP interacts specifically with the cytosolic tails of the dimeric GHR, identifying both Ubc13 and CHIP as novel factors in the regulation of cell surface availability of GHR.
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Affiliation(s)
- Johan A Slotman
- Department of Cell Biology, University Medical Center Utrecht and Institute of Biomembranes, 3584 CX Utrecht, The Netherlands
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da Silva Almeida AC, Strous GJ, van Rossum AGSH. βTrCP controls GH receptor degradation via two different motifs. Mol Endocrinol 2011; 26:165-77. [PMID: 22034227 DOI: 10.1210/me.2011-1211] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The physiological roles of GH are broad and include metabolism regulation and promotion of somatic growth. Therefore, the responsiveness of cells to GH must be tightly regulated. This is mainly achieved by a complex and well-controlled mechanism of GH receptor (GHR) endocytosis. GHR endocytosis occurs independently of GH and requires the ubiquitin ligase, SCF (βTrCP) that is recruited to the ubiquitin-dependent endocytosis (UbE) motif in the cytoplasmic tail of the GHR. In this study we report that, in addition to the UbE motif, a downstream degron, DSGRTS, binds to βTrCP. The WD40 residues on βTrCP involved in the interaction with this sequence are identical to the ones necessary for binding the classical motif, DSGxxS, in inhibitor of NFκB signalling, and β-catenin. Previously, we showed that this motif is not involved in GH-induced endocytosis. We show here that the DSGRTS sequence significantly contributes to GHR endocytosis/degradation in basal conditions, whereas the UbE motif is involved both in basal and GH-induced conditions. These findings explain the high rate of GHR degradation under basal conditions, which is important for regulating the responsiveness of cells to GH.
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Affiliation(s)
- Ana C da Silva Almeida
- Department of Cell Biology and Institute of Biomembranes, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
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