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Gonias SL. Plasminogen activator receptor assemblies in cell signaling, innate immunity, and inflammation. Am J Physiol Cell Physiol 2021; 321:C721-C734. [PMID: 34406905 DOI: 10.1152/ajpcell.00269.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) are serine proteases and major activators of fibrinolysis in mammalian systems. Because fibrinolysis is an essential component of the response to tissue injury, diverse cells, including cells that participate in the response to injury, have evolved receptor systems to detect tPA and uPA and initiate appropriate cell-signaling responses. Formation of functional receptor systems for the plasminogen activators requires assembly of diverse plasma membrane proteins, including but not limited to: the urokinase receptor (uPAR); integrins; N-formyl peptide receptor-2 (FPR2), receptor tyrosine kinases (RTKs), the N-methyl-d-aspartate receptor (NMDA-R), and low-density lipoprotein receptor-related protein-1 (LRP1). The cell-signaling responses elicited by tPA and uPA impact diverse aspects of cell physiology. This review describes rapidly evolving knowledge regarding the structure and function of plasminogen activator receptor assemblies. How these receptor assemblies regulate innate immunity and inflammation is then considered.
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Affiliation(s)
- Steven L Gonias
- Department of Pathology, University of California, San Diego, California
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2
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Príncipe C, Dionísio de Sousa IJ, Prazeres H, Soares P, Lima RT. LRP1B: A Giant Lost in Cancer Translation. Pharmaceuticals (Basel) 2021; 14:836. [PMID: 34577535 PMCID: PMC8469001 DOI: 10.3390/ph14090836] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 08/14/2021] [Accepted: 08/16/2021] [Indexed: 12/23/2022] Open
Abstract
Low-density lipoprotein receptor-related protein 1B (LRP1B) is a giant member of the LDLR protein family, which includes several structurally homologous cell surface receptors with a wide range of biological functions from cargo transport to cell signaling. LRP1B is among the most altered genes in human cancer overall. Found frequently inactivated by several genetic and epigenetic mechanisms, it has mostly been regarded as a putative tumor suppressor. Still, limitations in LRP1B studies exist, in particular associated with its huge size. Therefore, LRP1B expression and function in cancer remains to be fully unveiled. This review addresses the current understanding of LRP1B and the studies that shed a light on the LRP1B structure and ligands. It goes further in presenting increasing knowledge brought by technical and methodological advances that allow to better manipulate LRP1B expression in cells and to more thoroughly explore its expression and mutation status. New evidence is pushing towards the increased relevance of LRP1B in cancer as a potential target or translational prognosis and response to therapy biomarker.
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Affiliation(s)
- Catarina Príncipe
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (C.P.); (H.P.); (P.S.)
- Cancer Signalling and Metabolism Group, IPATIMUP—Institute of Molecular Pathology and Immunology, University of Porto, 4200-135 Porto, Portugal
| | - Isabel J. Dionísio de Sousa
- Department of Oncology, Centro Hospitalar Universitário de São João, 4200-450 Porto, Portugal;
- Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - Hugo Prazeres
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (C.P.); (H.P.); (P.S.)
- IPO-Coimbra, Portuguese Oncology Institute of Coimbra, 3000-075 Coimbra, Portugal
| | - Paula Soares
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (C.P.); (H.P.); (P.S.)
- Cancer Signalling and Metabolism Group, IPATIMUP—Institute of Molecular Pathology and Immunology, University of Porto, 4200-135 Porto, Portugal
- Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
- Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - Raquel T. Lima
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (C.P.); (H.P.); (P.S.)
- Cancer Signalling and Metabolism Group, IPATIMUP—Institute of Molecular Pathology and Immunology, University of Porto, 4200-135 Porto, Portugal
- Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
- Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
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3
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Black AR, Black JD. The complexities of PKCα signaling in cancer. Adv Biol Regul 2021; 80:100769. [PMID: 33307285 PMCID: PMC8141086 DOI: 10.1016/j.jbior.2020.100769] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 11/15/2020] [Indexed: 01/06/2023]
Abstract
Protein kinase C α (PKCα) is a ubiquitously expressed member of the PKC family of serine/threonine kinases with diverse functions in normal and neoplastic cells. Early studies identified anti-proliferative and differentiation-inducing functions for PKCα in some normal tissues (e.g., regenerating epithelia) and pro-proliferative effects in others (e.g., cells of the hematopoietic system, smooth muscle cells). Additional well documented roles of PKCα signaling in normal cells include regulation of the cytoskeleton, cell adhesion, and cell migration, and PKCα can function as a survival factor in many contexts. While a majority of tumors lose expression of PKCα, others display aberrant overexpression of the enzyme. Cancer-related mutations in PKCα are uncommon, but rare examples of driver mutations have been detected in certain cancer types (e. g., choroid gliomas). Here we review the role of PKCα in various cancers, describe mechanisms by which PKCα affects cancer-related cell functions, and discuss how the diverse functions of PKCα contribute to tumor suppressive and tumor promoting activities of the enzyme. We end the discussion by addressing mutations and expression of PKCα in tumors and the clinical relevance of these findings.
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Affiliation(s)
- Adrian R Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Jennifer D Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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4
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From the low-density lipoprotein receptor-related protein 1 to neuropathic pain: a potentially novel target. Pain Rep 2021; 6:e898. [PMID: 33981930 PMCID: PMC8108589 DOI: 10.1097/pr9.0000000000000898] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/21/2020] [Accepted: 12/25/2020] [Indexed: 12/12/2022] Open
Abstract
The low-density lipoprotein receptor–related protein 1 plays a major role in the regulation of neuroinflammation, neurodegeneration, neuroregeneration, neuropathic pain, and deficient cognitive functions. This review describes the roles of the low-density lipoprotein receptor–related protein 1 (LRP-1) in inflammatory pathways, nerve nerve degeneration and -regeneration and in neuropathic pain. Induction of LRP-1 is able to reduce the activation of the proinflammatory NFκB-mediated pathway and the mitogen-activated protein kinase (MAPK) c-Jun N-terminal kinase and p38 signaling pathways, in turn decreasing the production of inflammatory mediators. Low-density lipoprotein receptor-related protein 1 activation also decreases reactive astrogliosis and polarizes microglial cells and macrophages from a proinflammatory phenotype (M1) to an anti-inflammatory phenotype (M2), attenuating the neuroinflammatory environment. Low-density lipoprotein receptor-related protein 1 can also modulate the permeability of the blood–brain barrier and the blood–nerve barrier, thus regulating the infiltration of systemic insults and cells into the central and the peripheral nervous system, respectively. Furthermore, LRP-1 is involved in the maturation of oligodendrocytes and in the activation, migration, and repair phenotype of Schwann cells, therefore suggesting a major role in restoring the myelin sheaths upon injury. Low-density lipoprotein receptor-related protein 1 activation can indirectly decrease neurodegeneration and neuropathic pain by attenuation of the inflammatory environment. Moreover, LRP-1 agonists can directly promote neural cell survival and neurite sprouting, decrease cell death, and attenuate pain and neurological disorders by the inhibition of MAPK c-Jun N-terminal kinase and p38-pathway and activation of MAPK extracellular signal–regulated kinase pathway. In addition, activation of LRP-1 resulted in better outcomes for neuropathies such as Alzheimer disease, nerve injury, or diabetic peripheral neuropathy, attenuating neuropathic pain and improving cognitive functions. To summarize, LRP-1 plays an important role in the development of different experimental diseases of the nervous system, and it is emerging as a very interesting therapeutic target.
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Dyakin VV, Wisniewski TM, Lajtha A. Racemization in Post-Translational Modifications Relevance to Protein Aging, Aggregation and Neurodegeneration: Tip of the Iceberg. Symmetry (Basel) 2021; 13:455. [PMID: 34350031 PMCID: PMC8330555 DOI: 10.3390/sym13030455] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Homochirality of DNA and prevalent chirality of free and protein-bound amino acids in a living organism represents the challenge for modern biochemistry and neuroscience. The idea of an association between age-related disease, neurodegeneration, and racemization originated from the studies of fossils and cataract disease. Under the pressure of new results, this concept has a broader significance linking protein folding, aggregation, and disfunction to an organism's cognitive and behavioral functions. The integrity of cognitive function is provided by a delicate balance between the evolutionarily imposed molecular homo-chirality and the epigenetic/developmental impact of spontaneous and enzymatic racemization. The chirality of amino acids is the crucial player in the modulation the structure and function of proteins, lipids, and DNA. The collapse of homochirality by racemization is the result of the conformational phase transition. The racemization of protein-bound amino acids (spontaneous and enzymatic) occurs through thermal activation over the energy barrier or by the tunnel transfer effect under the energy barrier. The phase transition is achieved through the intermediate state, where the chirality of alpha carbon vanished. From a thermodynamic consideration, the system in the homo-chiral (single enantiomeric) state is characterized by a decreased level of entropy. The oscillating protein chirality is suggesting its distinct significance in the neurotransmission and flow of perceptual information, adaptive associative learning, and cognitive laterality. The common pathological hallmarks of neurodegenerative disorders include protein misfolding, aging, and the deposition of protease-resistant protein aggregates. Each of the landmarks is influenced by racemization. The brain region, cell type, and age-dependent racemization critically influence the functions of many intracellular, membrane-bound, and extracellular proteins including amyloid precursor protein (APP), TAU, PrP, Huntingtin, α-synuclein, myelin basic protein (MBP), and collagen. The amyloid cascade hypothesis in Alzheimer's disease (AD) coexists with the failure of amyloid beta (Aβ) targeting drug therapy. According to our view, racemization should be considered as a critical factor of protein conformation with the potential for inducing order, disorder, misfolding, aggregation, toxicity, and malfunctions.
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Affiliation(s)
- Victor V. Dyakin
- Virtual Reality Perception Lab (VRPL), The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USA
| | - Thomas M. Wisniewski
- Departments of Neurology, Pathology and Psychiatry, Center for Cognitive Neurology, New York University School of Medicine, New York, NY 10016, USA
| | - Abel Lajtha
- Center for Neurochemistry, The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USA
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6
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Liu JJ, Chiu YT, Chen C, Huang P, Mann M, Liu-Chen LY. Pharmacological and phosphoproteomic approaches to roles of protein kinase C in kappa opioid receptor-mediated effects in mice. Neuropharmacology 2020; 181:108324. [PMID: 32976891 DOI: 10.1016/j.neuropharm.2020.108324] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/10/2020] [Accepted: 09/15/2020] [Indexed: 12/17/2022]
Abstract
Kappa opioid receptor (KOR) agonists possess adverse dysphoric and psychotomimetic effects, thus limiting their applications as non-addictive anti-pruritic and analgesic agents. Here, we showed that protein kinase C (PKC) inhibition preserved the beneficial antinociceptive and antipruritic effects of KOR agonists, but attenuated the adverse condition placed aversion (CPA), sedation, and motor incoordination in mice. Using a large-scale mass spectrometry-based phosphoproteomics of KOR-mediated signaling in the mouse brain, we observed PKC-dependent modulation of G protein-coupled receptor kinases and Wnt pathways at 5 min; stress signaling, cytoskeleton, mTOR signaling and receptor phosphorylation, including cannabinoid receptor CB1 at 30 min. We further demonstrated that inhibition of CB1 attenuated KOR-mediated CPA. Our results demonstrated the feasibility of in vivo biochemical dissection of signaling pathways that lead to side effects.
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Affiliation(s)
- Jeffrey J Liu
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Yi-Ting Chiu
- Center for Substance Abuse Research & Department of Pharmacology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Chongguang Chen
- Center for Substance Abuse Research & Department of Pharmacology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Peng Huang
- Center for Substance Abuse Research & Department of Pharmacology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research & Department of Pharmacology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA.
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7
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Laberge A, Ayoub A, Arif S, Larochelle S, Garnier A, Moulin VJ. α‐2‐Macroglobulin induces the shedding of microvesicles from cutaneous wound myofibroblasts. J Cell Physiol 2018; 234:11369-11379. [DOI: 10.1002/jcp.27794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 10/31/2018] [Indexed: 01/21/2023]
Affiliation(s)
- Alexandra Laberge
- Centre de Recherche en Organogenèse Expérimentale de l'Université Laval (LOEX) Quebec QC Canada
- Centre de Recherche du CHU de Quebec‐Université Laval Quebec QC Canada
| | - Akram Ayoub
- Centre de Recherche en Organogenèse Expérimentale de l'Université Laval (LOEX) Quebec QC Canada
- Centre de Recherche du CHU de Quebec‐Université Laval Quebec QC Canada
| | - Syrine Arif
- Centre de Recherche en Organogenèse Expérimentale de l'Université Laval (LOEX) Quebec QC Canada
- Centre de Recherche du CHU de Quebec‐Université Laval Quebec QC Canada
| | - Sébastien Larochelle
- Centre de Recherche en Organogenèse Expérimentale de l'Université Laval (LOEX) Quebec QC Canada
- Centre de Recherche du CHU de Quebec‐Université Laval Quebec QC Canada
| | - Alain Garnier
- Department of Chemical Engineering Faculty of Sciences and Engineering, Université Laval Quebec QC Canada
| | - Véronique J. Moulin
- Centre de Recherche en Organogenèse Expérimentale de l'Université Laval (LOEX) Quebec QC Canada
- Centre de Recherche du CHU de Quebec‐Université Laval Quebec QC Canada
- Department of Surgery Faculty of Medicine, Université Laval Quebec QC Canada
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8
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Wujak L, Böttcher RT, Pak O, Frey H, El Agha E, Chen Y, Schmitt S, Bellusci S, Schaefer L, Weissmann N, Fässler R, Wygrecka M. Low density lipoprotein receptor-related protein 1 couples β1 integrin activation to degradation. Cell Mol Life Sci 2018; 75:1671-1685. [PMID: 29116364 PMCID: PMC11105666 DOI: 10.1007/s00018-017-2707-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/19/2017] [Accepted: 11/01/2017] [Indexed: 01/09/2023]
Abstract
Low density lipoprotein receptor-related protein (LRP) 1 modulates cell adhesion and motility under normal and pathological conditions. Previous studies documented that LRP1 binds several integrin receptors and mediates their trafficking to the cell surface and endocytosis. However, the mechanism by which LRP1 may regulate integrin activation remains unknown. Here we report that LRP1 promotes the activation and subsequent degradation of β1 integrin and thus supports cell adhesion, spreading, migration and integrin signaling on fibronectin. LRP1 interacts with surface β1 integrin, binds the integrin activator kindlin2 and stimulates β1 integrin-kindlin2 complex formation. Specifically, serine 76 in the LRP1 cytoplasmic tail is crucial for the interaction with kindlin2, β1 integrin activation and cell adhesion. Interestingly, a loss of LRP1 induces the accumulation of several integrin receptors on the cell surface. Following internalization, intracellular trafficking of integrins is driven by LRP1 in a protein kinase C- and class II myosin-dependent manner. Ultimately, LRP1 dictates the fate of endocytosed β1 integrin by directing it down the pathway of lysosomal and proteasomal degradation. We propose that LRP1 mediates cell adhesion by orchestrating a multi-protein pathway to activate, traffic and degrade integrins. Thus, LRP1 may serve as a focal point in the integrin quality control system to ensure a firm connection to the extracellular matrix.
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Affiliation(s)
- Lukasz Wujak
- Department of Biochemistry, Justus Liebig University, 35392, Giessen, Germany
| | - Ralph T Böttcher
- Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
| | - Oleg Pak
- Excellence Cluster Cardio-Pulmonary System, Justus Liebig University, 35392, Giessen, Germany
| | - Helena Frey
- Institute of Pharmacology and Toxicology, Goethe University School of Medicine, University Hospital, 60590, Frankfurt am Main, Germany
| | - Elie El Agha
- Excellence Cluster Cardio-Pulmonary System, Justus Liebig University, 35392, Giessen, Germany
| | - Ying Chen
- Department of Biochemistry, Justus Liebig University, 35392, Giessen, Germany
| | - Sigrid Schmitt
- Department of Biochemistry, Justus Liebig University, 35392, Giessen, Germany
| | - Saverio Bellusci
- Excellence Cluster Cardio-Pulmonary System, Justus Liebig University, 35392, Giessen, Germany
| | - Liliana Schaefer
- Institute of Pharmacology and Toxicology, Goethe University School of Medicine, University Hospital, 60590, Frankfurt am Main, Germany
| | - Norbert Weissmann
- Excellence Cluster Cardio-Pulmonary System, Justus Liebig University, 35392, Giessen, Germany
| | - Reinhard Fässler
- Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Malgorzata Wygrecka
- Department of Biochemistry, Justus Liebig University, 35392, Giessen, Germany.
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Intrinsic dynamics study identifies two amino acids of TIMP-1 critical for its LRP-1-mediated endocytosis in neurons. Sci Rep 2017; 7:5375. [PMID: 28710453 PMCID: PMC5511134 DOI: 10.1038/s41598-017-05039-z] [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: 10/04/2016] [Accepted: 05/24/2017] [Indexed: 01/28/2023] Open
Abstract
The tissue inhibitor of metalloproteinases-1 (TIMP-1) exerts inhibitory activity against matrix metalloproteinases and cytokine-like effects. We previously showed that TIMP-1 reduces neurite outgrowth in mouse cortical neurons and that this cytokine-like effect depends on TIMP-1 endocytosis mediated by the low-density lipoprotein receptor-related protein-1 (LRP-1). To gain insight into the interaction between TIMP-1 and LRP-1, we considered conformational changes that occur when a ligand binds to its receptor. TIMP-1 conformational changes have been studied using biomolecular simulations, and our results provide evidence for a hinge region that is critical for the protein movement between the N- and C-terminal TIMP-1 domains. In silico mutants have been proposed on residues F12 and K47, which are located in the hinge region. Biological analyses of these mutants show that F12A or K47A mutation does not alter MMP inhibitory activity but impairs the effect of TIMP-1 on neurite outgrowth. Interestingly, these mutants bind to LRP-1 but are not endocytosed. We conclude that the intrinsic dynamics of TIMP-1 are not involved in its binding to LRP-1 but rather in the initiation of endocytosis and associated biological effects.
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Au DT, Strickland DK, Muratoglu SC. The LDL Receptor-Related Protein 1: At the Crossroads of Lipoprotein Metabolism and Insulin Signaling. J Diabetes Res 2017; 2017:8356537. [PMID: 28584820 PMCID: PMC5444004 DOI: 10.1155/2017/8356537] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 04/11/2017] [Indexed: 12/30/2022] Open
Abstract
The metabolic syndrome is an escalating worldwide public health concern. Defined by a combination of physiological, metabolic, and biochemical factors, the metabolic syndrome is used as a clinical guideline to identify individuals with a higher risk for type 2 diabetes and cardiovascular disease. Although risk factors for type 2 diabetes and cardiovascular disease have been known for decades, the molecular mechanisms involved in the pathophysiology of these diseases and their interrelationship remain unclear. The LDL receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that is widely expressed in several tissues. As a member of the LDL receptor family, LRP1 is involved in the clearance of chylomicron remnants from the circulation and has been demonstrated to be atheroprotective. Recently, studies have shown that LRP1 is involved in insulin receptor trafficking and regulation and glucose metabolism. This review summarizes the role of tissue-specific LRP1 in insulin signaling and its potential role as a link between lipoprotein and glucose metabolism in diabetes.
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Affiliation(s)
- Dianaly T. Au
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Dudley K. Strickland
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Selen C. Muratoglu
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- *Selen C. Muratoglu:
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11
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Noyes NC, Hampton B, Migliorini M, Strickland DK. Regulation of Itch and Nedd4 E3 Ligase Activity and Degradation by LRAD3. Biochemistry 2016; 55:1204-13. [DOI: 10.1021/acs.biochem.5b01218] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Nathaniel C. Noyes
- Center for Vascular and Inflammatory Diseases and the ‡Departments
of Surgery and §Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Brian Hampton
- Center for Vascular and Inflammatory Diseases and the ‡Departments
of Surgery and §Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Mary Migliorini
- Center for Vascular and Inflammatory Diseases and the ‡Departments
of Surgery and §Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Dudley K. Strickland
- Center for Vascular and Inflammatory Diseases and the ‡Departments
of Surgery and §Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
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12
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Ramanathan A, Nelson AR, Sagare AP, Zlokovic BV. Impaired vascular-mediated clearance of brain amyloid beta in Alzheimer's disease: the role, regulation and restoration of LRP1. Front Aging Neurosci 2015; 7:136. [PMID: 26236233 PMCID: PMC4502358 DOI: 10.3389/fnagi.2015.00136] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/02/2015] [Indexed: 12/12/2022] Open
Abstract
Amyloid beta (Aβ) homeostasis in the brain is governed by its production and clearance mechanisms. An imbalance in this homeostasis results in pathological accumulations of cerebral Aβ, a characteristic of Alzheimer’s disease (AD). While Aβ may be cleared by several physiological mechanisms, a major route of Aβ clearance is the vascular-mediated removal of Aβ from the brain across the blood-brain barrier (BBB). Here, we discuss the role of the predominant Aβ clearance protein—low-density lipoprotein receptor-related protein 1 (LRP1)—in the efflux of Aβ from the brain. We also outline the multiple factors that influence the function of LRP1-mediated Aβ clearance, such as its expression, shedding, structural modification and transcriptional regulation by other genes. Finally, we summarize approaches aimed at restoring LRP1-mediated Aβ clearance from the brain.
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Affiliation(s)
- Anita Ramanathan
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
| | - Amy R Nelson
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
| | - Abhay P Sagare
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
| | - Berislav V Zlokovic
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
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13
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Wei J, Fu ZY, Li PS, Miao HH, Li BL, Ma YT, Song BL. The clathrin adaptor proteins ARH, Dab2, and numb play distinct roles in Niemann-Pick C1-Like 1 versus low density lipoprotein receptor-mediated cholesterol uptake. J Biol Chem 2014; 289:33689-700. [PMID: 25331956 PMCID: PMC4246119 DOI: 10.1074/jbc.m114.593764] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 10/08/2014] [Indexed: 12/21/2022] Open
Abstract
The uptake of circulating low density lipoproteins (LDL) is mediated by LDL receptor (LDLR) through clathrin-dependent endocytosis. At the early stage of this process, adaptor proteins ARH and Dab2 specifically bind the endocytic signal motif in LDLR and recruit clathrin/AP2 to initiate internalization. On the other hand, intestinal cholesterol is absorbed by Niemann-Pick C1-Like 1 (NPC1L1) through clathrin-dependent endocytosis. Another adaptor protein, Numb recognizes the endocytic motif in NPC1L1 C terminus and couples NPC1L1 to endocytic machinery. The ARH, Dab2, and Numb proteins contain a homogeneous phosphotyrosine binding (PTB) domain that directly binds endocytic motifs. Because ARH, Dab2, and Numb are all PTB domain family members, the emerging mystery is whether these adaptors act complementally in LDLR and NPC1L1 endocytosis. Here, we found that ARH and Dab2 did not bind NPC1L1 and were not required for NPC1L1 internalization. Similarly, Numb lacked the ability to interact with the LDLR C terminus and was dispensable for LDL uptake. Only the Numb isoforms with shorter PTB domain could facilitate NPC1L1 endocytosis. Besides the reported function in intestinal cholesterol absorption, Numb also mediated cholesterol reabsorption from bile in liver. We further identified a Numb variant with G595D substitution in humans of low blood LDL-cholesterol. The G595D substitution impaired NPC1L1 internalization and cholesterol reabsorption, due to attenuating affinity of Numb to clathrin/AP2. These results demonstrate that Numb specifically regulates NPC1L1-mediated cholesterol absorption both in human intestine and liver, distinct from ARH and Dab2, which selectively participate in LDLR-mediated LDL uptake.
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Affiliation(s)
- Jian Wei
- From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031
| | - Zhen-Yan Fu
- the Department of Cardiovascular Medicine, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, and
| | - Pei-Shan Li
- From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031
| | - Hong-Hua Miao
- From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031
| | - Bo-Liang Li
- From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031
| | - Yi-Tong Ma
- the Department of Cardiovascular Medicine, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, and
| | - Bao-Liang Song
- From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, the College of Life Sciences, Wuhan University, Wuhan 430072, China
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Emonard H, Théret L, Bennasroune AH, Dedieu S. Regulation of LRP-1 expression: make the point. ACTA ACUST UNITED AC 2014; 62:84-90. [PMID: 24661974 DOI: 10.1016/j.patbio.2014.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 02/14/2014] [Indexed: 12/14/2022]
Abstract
The low-density lipoprotein receptor-related protein-1 (LRP-1) is a membrane receptor displaying both scavenging and signaling functions. The wide variety of extracellular ligands and of cytoplasmic scaffolding and signaling proteins interacting with LRP-1 gives it a major role not only in physiological processes, such as embryogenesis and development, but also in critical pathological situations, including cancer and neurological disorders. In this review, we describe the molecular mechanisms involved at distinct levels in the regulation of LRP-1, from its expression to the proper location and stability at the cell surface.
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Affiliation(s)
- H Emonard
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France
| | - L Théret
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France
| | - A H Bennasroune
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France
| | - S Dedieu
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France.
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15
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Craig J, Mikhailenko I, Noyes N, Migliorini M, Strickland DK. The LDL receptor-related protein 1 (LRP1) regulates the PDGF signaling pathway by binding the protein phosphatase SHP-2 and modulating SHP-2- mediated PDGF signaling events. PLoS One 2013; 8:e70432. [PMID: 23922991 PMCID: PMC3724782 DOI: 10.1371/journal.pone.0070432] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 06/18/2013] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The PDGF signaling pathway plays a major role in several biological systems, including vascular remodeling that occurs following percutaneous transluminal coronary angioplasty. Recent studies have shown that the LDL receptor-related protein 1 (LRP1) is a physiological regulator of the PDGF signaling pathway. The underlying mechanistic details of how this regulation occurs have yet to be resolved. Activation of the PDGF receptor β (PDGFRβ) leads to tyrosine phosphorylation of the LRP1 cytoplasmic domain within endosomes and generates an LRP1 molecule with increased affinity for adaptor proteins such as SHP-2 that are involved in signaling pathways. SHP-2 is a protein tyrosine phosphatase that positively regulates the PDGFRβ pathway, and is required for PDGF-mediated chemotaxis. We investigated the possibility that LRP1 may regulate the PDGFRβ signaling pathway by binding SHP-2 and competing with the PDGFRβ for this molecule. METHODOLOGY/PRINCIPAL FINDINGS To quantify the interaction between SHP-2 and phosphorylated forms of the LRP1 intracellular domain, we utilized an ELISA with purified recombinant proteins. These studies revealed high affinity binding of SHP-2 to phosphorylated forms of both LRP1 intracellular domain and the PDGFRβ kinase domain. By employing the well characterized dynamin inhibitor, dynasore, we established that PDGF-induced SHP-2 phosphorylation primarily occurs within endosomal compartments, the same compartments in which LRP1 is tyrosine phosphorylated by activated PDGFRβ. Immunofluorescence studies revealed colocalization of LRP1 and phospho-SHP-2 following PDGF stimulation of fibroblasts. To define the contribution of LRP1 to SHP-2-mediated PDGF chemotaxis, we employed fibroblasts expressing LRP1 and deficient in LRP1 and a specific SHP-2 inhibitor, NSC-87877. Our results reveal that LRP1 modulates SHP-2-mediated PDGF-mediated chemotaxis. CONCLUSIONS/SIGNIFICANCE Our data demonstrate that phosphorylated forms of LRP1 and PDGFRβ compete for SHP-2 binding, and that expression of LRP1 attenuates SHP-2-mediated PDGF signaling events.
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Affiliation(s)
- Julie Craig
- Center for Vascular and Inflammatory Diseases and
| | - Irina Mikhailenko
- Center for Vascular and Inflammatory Diseases and
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | | | - Mary Migliorini
- Center for Vascular and Inflammatory Diseases and
- Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Dudley K. Strickland
- Center for Vascular and Inflammatory Diseases and
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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16
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Barcelona PF, Jaldín-Fincati JR, Sánchez MC, Chiabrando GA. Activated α2-macroglobulin induces Müller glial cell migration by regulating MT1-MMP activity through LRP1. FASEB J 2013; 27:3181-97. [PMID: 23640058 DOI: 10.1096/fj.12-221598] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In retinal proliferative diseases, Müller glial cells (MGCs) acquire migratory abilities. However, the mechanisms that regulate this migration remain poorly understood. In addition, proliferative disorders associated with enhanced activities of matrix metalloprotease 2 (MMP-2) and MMP-9 also present increased levels of the protease inhibitor α2-macroglobulin (α2M) and its receptor, the low-density lipoprotein receptor-related protein 1 (LRP1). In the present work, we investigated whether the protease activated form of α2M, α2M*, and LRP1 are involved with the MGC migratory process. By performing wound-scratch migration and zymography assays, we demonstrated that α2M* induced cell migration and proMMP-2 activation in the human Müller glial cell line, MIO-M1. This induction was blocked when LRP1 and MT1-MMP were knocked down with siRNA techniques. Using fluorescence microscopy and biochemical procedures, we found that α2M* induced an increase in LRP1 and MT1-MMP accumulation in early endosomes, followed by endocytic recycling and intracellular distribution of MT1-MMP toward cellular protrusions. Moreover, Rab11-dominant negative mutant abrogated MT1-MMP recycling pathway, cell migration, and proMMP-2 activation induced by α2M*. In conclusion, α2M*, through its receptor LRP1, induces cellular migration of Müller glial cells by a mechanism that involves MT1-MMP intracellular traffic to the plasma membrane by a Rab11-dependent recycling pathway.
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Affiliation(s)
- Pablo F Barcelona
- Centro de Investigaciones en Bioquímica Clínica e Inmunología-Consejo Nacional de Investigaciones Cientificas y Tecnicas (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, (5000) Córdoba, Argentina
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17
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Sagare AP, Deane R, Zlokovic BV. Low-density lipoprotein receptor-related protein 1: a physiological Aβ homeostatic mechanism with multiple therapeutic opportunities. Pharmacol Ther 2012; 136:94-105. [PMID: 22820095 PMCID: PMC3432694 DOI: 10.1016/j.pharmthera.2012.07.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 07/03/2012] [Indexed: 11/29/2022]
Abstract
Low-density lipoprotein receptor-related protein-1 (LRP1) is the main cell surface receptor involved in brain and systemic clearance of the Alzheimer's disease (AD) toxin amyloid-beta (Aβ). In plasma, a soluble form of LRP1 (sLRP1) is the major transport protein for peripheral Aβ. LRP1 in brain endothelium and mural cells mediates Aβ efflux from brain by providing a transport mechanism for Aβ across the blood-brain barrier (BBB). sLRP1 maintains a plasma 'sink' activity for Aβ through binding of peripheral Aβ which in turn inhibits re-entry of free plasma Aβ into the brain. LRP1 in the liver mediates systemic clearance of Aβ. In AD, LRP1 expression at the BBB is reduced and Aβ binding to circulating sLRP1 is compromised by oxidation. Cell surface LRP1 and circulating sLRP1 represent druggable targets which can be therapeutically modified to restore the physiological mechanisms of brain Aβ homeostasis. In this review, we discuss how increasing LRP1 expression at the BBB and liver with lifestyle changes, statins, plant-based active principles and/or gene therapy on one hand, and how replacing dysfunctional plasma sLRP1 on the other regulate Aβ clearance from brain ultimately controlling the onset and/or progression of AD.
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Affiliation(s)
- Abhay P. Sagare
- Department of Physiology and Biophysics, and Center for Neurodegeneration and Regeneration at the Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, 1501 San Pablo Street, Los Angeles, CA 90089, United States
| | - Rashid Deane
- Department of Neurosurgery, Arthur Kornberg Medical Research Building, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Berislav V. Zlokovic
- Department of Physiology and Biophysics, and Center for Neurodegeneration and Regeneration at the Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, 1501 San Pablo Street, Los Angeles, CA 90089, United States
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18
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Proulx DP, Rouleau P, Paré I, Vallières-Noël MM, Bazin R. Interaction between intravenous immunoglobulin (IVIg) and the low-density lipoprotein receptor-related protein 1: a role for transcytosis across the blood brain barrier? J Neuroimmunol 2012; 251:39-44. [PMID: 22796178 DOI: 10.1016/j.jneuroim.2012.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 06/19/2012] [Accepted: 06/25/2012] [Indexed: 01/28/2023]
Abstract
Intravenous immunoglobulin (IVIg) is a therapeutic preparation of plasma-derived human IgG and is increasingly used for the treatment of several neurological inflammatory disorders. However, it is not clear whether the IgG molecules contained in IVIg can actually cross the BBB in treated patients. We recently showed that LRP1, an endocytic receptor involved in transcytosis of several proteins across the BBB was able to interact with IVIg. In the present study, we show that LRP1 is involved in IVIg internalization inside living cells. Our data also suggest that following internalization, IVIg is recycled to the cell surface, raising the possibility that LRP1 can mediate IVIg transcytosis across the BBB. Finally, we show that IVIg-LRP1 interaction leads to LRP1 tyrosine phosphorylation.
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Abstract
The low-density lipoprotein receptor-related protein 1 (LRP-1) is a large endocytic receptor mediating the clearance of various molecules from the extracellular matrix. In the field of cancer, LRP-1-mediated endocytosis was first associated with antitumor properties. However, recent results suggested that LRP-1 may coordinate the adhesion-deadhesion balance in malignant cells to support tumor progression. Here, we observed that LRP-1 silencing or RAP (receptor-associated protein) treatment led to accumulation of CD44 at the tumor cell surface. Moreover, we evidenced a tight interaction between CD44 and LRP-1, not exclusively localized in lipid rafts. Overexpression of LRP-1-derived minireceptors indicated that the fourth ligand-binding cluster of LRP-1 is required to bind CD44. Labeling of CD44 with EEA1 and LAMP-1 showed that internalized CD44 is routed through early endosomes toward lysosomes in a LRP-1-dependent pathway. LRP-1-mediated internalization of CD44 was highly reduced under hyperosmotic conditions but poorly affected by membrane cholesterol depletion, revealing that it proceeds mostly via clathrin-coated pits. Finally, we demonstrated that CD44 silencing abolishes RAP-induced tumor cell attachment, revealing that cell surface accumulation of CD44 under LRP-1 blockade is mainly responsible for the stimulation of tumor cell adhesion. Altogether, our data shed light on the LRP-1-mediated internalization of CD44 that appeared critical to define the adhesive properties of tumor cells.
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20
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Beyer AS, von Einem B, Schwanzar D, Keller IE, Hellrung A, Thal DR, Ingelsson M, Makarova A, Deng M, Chhabra ES, Pröpper C, Böckers TM, Hyman BT, von Arnim CA. Engulfment adapter PTB domain containing 1 interacts with and affects processing of the amyloid-β precursor protein. Neurobiol Aging 2012; 33:732-43. [DOI: 10.1016/j.neurobiolaging.2010.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 06/08/2010] [Accepted: 06/09/2010] [Indexed: 01/22/2023]
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LRAD3, a novel low-density lipoprotein receptor family member that modulates amyloid precursor protein trafficking. J Neurosci 2011; 31:10836-46. [PMID: 21795536 DOI: 10.1523/jneurosci.5065-10.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We have identified a novel low-density lipoprotein (LDL) receptor family member, termed LDL receptor class A domain containing 3 (LRAD3), which is expressed in neurons. The LRAD3 gene encodes an ∼50 kDa type I transmembrane receptor with an ectodomain containing three LDLa repeats, a transmembrane domain, and a cytoplasmic domain containing a conserved dileucine internalization motif and two polyproline motifs with potential to interact with WW-domain-containing proteins. Immunohistochemical analysis of mouse brain reveals LRAD3 expression in the cortex and hippocampus. In the mouse hippocampal-derived cell line HT22, LRAD3 partially colocalizes with amyloid precursor protein (APP) and interacts with APP as revealed by coimmunoprecipitation experiments. To identify the portion of APP that interacts with LRAD3, we used solid-phase binding assays that demonstrated that LRAD3 failed to bind to a soluble APP fragment (sAPPα) released after α-secretase cleavage. In contrast, C99, the β-secretase product that remains cell associated, coprecipitated with LRAD3, confirming that regions within this portion of APP are important for associating with LRAD3. The association of LRAD3 with APP increases the amyloidogenic pathway of APP processing, resulting in a decrease in sAPPα production and increased Aβ peptide production. Pulse-chase experiments confirm that LRAD3 expression significantly decreases the cellular half-life of mature APP. These results reveal that LRAD3 influences APP processing and raises the possibility that LRAD3 alters APP function in neurons, including its downstream signaling.
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22
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Ranganathan S, Cao C, Catania J, Migliorini M, Zhang L, Strickland DK. Molecular basis for the interaction of low density lipoprotein receptor-related protein 1 (LRP1) with integrin alphaMbeta2: identification of binding sites within alphaMbeta2 for LRP1. J Biol Chem 2011; 286:30535-30541. [PMID: 21676865 DOI: 10.1074/jbc.m111.265413] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The LDL receptor-related protein 1 (LRP1) is a large endocytic receptor that controls macrophage migration in part by interacting with β(2) integrin receptors. However, the molecular mechanism underlying LRP1 integrin recognition is poorly understood. Here, we report that LRP1 specifically recognizes α(M)β(2) but not its homologous receptor α(L)β(2). The interaction between these two cellular receptors in macrophages is significantly enhanced upon α(M)β(2) activation by LPS and is mediated by multiple regions in both LRP1 and α(M)β(2). Specifically, we find that both the heavy and light chains of LRP1 are involved in α(M)β(2) binding. Within the heavy chain, the binding is mediated primarily via the second and fourth ligand binding repeats. For α(M)β(2), we find that the α(M)-I domain represents a major LRP1 recognition site. Indeed, substitution of the I domain of the α(L)β(2) receptor with that of α(M) confers the α(L)β(2) receptor with the ability to interact with LRP1. Furthermore, we show that residues (160)EQLKKSKTL(170) within the α(M)-I domain represent a major LRP1 recognition site. Given that perturbation of this specific sequence leads to altered adhesive activity of α(M)β(2), our finding suggests that binding of LRP1 to α(M)β(2) could alter integrin function. Indeed, we further demonstrate that the soluble form of LRP1 (sLRP1) inhibits α(M)β(2)-mediated adhesion of cells to fibrinogen. These studies suggest that sLRP1 may attenuate inflammation by modulating integrin function.
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Affiliation(s)
- Sripriya Ranganathan
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201; Surgery, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Chunzhang Cao
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201; the Departments of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Jason Catania
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Molly Migliorini
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Li Zhang
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201; the Departments of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201.
| | - Dudley K Strickland
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201; Surgery, University of Maryland School of Medicine, Baltimore, Maryland 21201; the Departments of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201.
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Cáceres LC, Bonacci GR, Sánchez MC, Chiabrando GA. Activated α(2) macroglobulin induces matrix metalloproteinase 9 expression by low-density lipoprotein receptor-related protein 1 through MAPK-ERK1/2 and NF-κB activation in macrophage-derived cell lines. J Cell Biochem 2011; 111:607-17. [PMID: 20568116 DOI: 10.1002/jcb.22737] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Macrophages under certain stimuli induce matrix metalloproteinase 9 (MMP-9) expression and protein secretion through the activation of MAPK-ERK and NF-κB signaling pathways. Previously, we demonstrated that activated α(2)-macroglulin (α(2)M*) through the interaction with its receptor low-density lipoprotein receptor-related protein 1 (LRP1) induces macrophage proliferation mediated by the activation of MAPK-ERK1/2. In the present work, we examined whether α(2)M*/LRP1interaction could induce the MMP-9 production in J774 and Raw264.7 macrophage-derived cell lines. It was shown that α(2)M* promoted MMP-9 expression and protein secretion by LRP1 in both macrophage-derived cell lines, which was mediated by the activation of MAPK-ERK1/2 and NF-κB. Both intracellular signaling pathways activated by α(2)M* were effectively blocked by calphostin-C, suggesting involvement of PKC. In addition, we demonstrate that α(2)M* produced extracellular calcium influx via LRP1. However, when the intracellular calcium mobilization was inhibited by BAPTA-AM, the α(2)M*-induced MAPK-ER1/2 activation was fully blocked in both macrophage cell lines. Finally, using specific pharmacological inhibitors for PKC, Mek1, and NF-κB, it was shown that the α(2)M*-induced MMP-9 protein secretion was inhibited, indicating that the MMP production promoted by the α(2)M*/LRP1 interaction required the activation of both signaling pathways. These findings may prove useful in the understanding of the macrophage LRP1 role in the vascular wall during atherogenic plaque progression.
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Affiliation(s)
- Leandro C Cáceres
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Centro de Investigaciones en Bioquímica Clínica e Inmunología, Ciudad Universitaria 5000, Córdoba, Argentina
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24
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Langlois B, Perrot G, Schneider C, Henriet P, Emonard H, Martiny L, Dedieu S. LRP-1 promotes cancer cell invasion by supporting ERK and inhibiting JNK signaling pathways. PLoS One 2010; 5:e11584. [PMID: 20644732 PMCID: PMC2904376 DOI: 10.1371/journal.pone.0011584] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 06/20/2010] [Indexed: 01/16/2023] Open
Abstract
Background The low-density lipoprotein receptor-related protein-1 (LRP-1) is an endocytic receptor mediating the clearance of various extracellular molecules involved in the dissemination of cancer cells. LRP-1 thus appeared as an attractive receptor for targeting the invasive behavior of malignant cells. However, recent results suggest that LRP-1 may facilitate the development and growth of cancer metastases in vivo, but the precise contribution of the receptor during cancer progression remains to be elucidated. The lack of mechanistic insights into the intracellular signaling networks downstream of LRP-1 has prevented the understanding of its contribution towards cancer. Methodology/Principal Findings Through a short-hairpin RNA-mediated silencing approach, we identified LRP-1 as a main regulator of ERK and JNK signaling in a tumor cell context. Co-immunoprecipitation experiments revealed that LRP-1 constitutes an intracellular docking site for MAPK containing complexes. By using pharmacological agents, constitutively active and dominant-negative kinases, we demonstrated that LRP-1 maintains malignant cells in an adhesive state that is favorable for invasion by activating ERK and inhibiting JNK. We further demonstrated that the LRP-1-dependent regulation of MAPK signaling organizes the cytoskeletal architecture and mediates adhesive complex turnover in cancer cells. Moreover, we found that LRP-1 is tethered to the actin network and to focal adhesion sites and controls ERK and JNK targeting to talin-rich structures. Conclusions We identified ERK and JNK as the main molecular relays by which LRP-1 regulates focal adhesion disassembly of malignant cells to support invasion.
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Affiliation(s)
- Benoit Langlois
- Université de Reims Champagne-Ardenne, CNRS UMR 6237 MEDyC, Laboratoire SiRMa, Campus Moulin de la Housse, Reims, France
| | - Gwenn Perrot
- Université de Reims Champagne-Ardenne, CNRS UMR 6237 MEDyC, Laboratoire SiRMa, Campus Moulin de la Housse, Reims, France
| | - Christophe Schneider
- Université de Reims Champagne-Ardenne, CNRS UMR 6237 MEDyC, Laboratoire SiRMa, Campus Moulin de la Housse, Reims, France
| | - Patrick Henriet
- Cell Biology Unit, de Duve Institute and Université Catholique de Louvain, Brussels, Belgium
| | - Hervé Emonard
- Université de Reims Champagne-Ardenne, CNRS UMR 6237 MEDyC, Laboratoire SiRMa, Campus Moulin de la Housse, Reims, France
| | - Laurent Martiny
- Université de Reims Champagne-Ardenne, CNRS UMR 6237 MEDyC, Laboratoire SiRMa, Campus Moulin de la Housse, Reims, France
| | - Stéphane Dedieu
- Université de Reims Champagne-Ardenne, CNRS UMR 6237 MEDyC, Laboratoire SiRMa, Campus Moulin de la Housse, Reims, France
- * E-mail:
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25
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Meng H, Zhang X, Lee SJ, Strickland DK, Lawrence DA, Wang MM. Low density lipoprotein receptor-related protein-1 (LRP1) regulates thrombospondin-2 (TSP2) enhancement of Notch3 signaling. J Biol Chem 2010; 285:23047-55. [PMID: 20472562 DOI: 10.1074/jbc.m110.144634] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Intracellular trafficking of Notch and Notch ligands modulates signaling, suggesting that choreography of ligand and receptor translocation is essential for optimal Notch activity. Indeed, a major model for Notch signaling posits that Notch trans-endocytosis into the ligand-expressing (signal sending) cell is a key driving force for Notch signal transduction. The extracellular protein thrombospondin-2 (TSP2) enhances Notch signaling and binds to both Jagged1 and Notch3 ectodomains, potentially bridging two essential extracellular components of Notch signaling. We investigated the role of low density lipoprotein receptor-related protein-1 (LRP1), a TSP2 receptor, in the regulation of Notch3 signaling. TSP2 potentiation of Notch is blocked by the receptor-associated protein (an inhibitor of low density lipoprotein receptor-related protein function) and requires LRP1 expression in the signal-sending cell. TSP2 stimulates Notch3 endocytosis into wild type fibroblasts but not LRP1-deficient fibroblasts. Finally, recombinant Notch3 and Jagged1 interact with the LRP1 85-kDa B-chain, a subunit that lacks known ligand binding function. Our data suggest that LRP1 and TSP2 stimulate Notch activity by driving trans-endocytosis of the Notch ectodomain into the signal-sending cell and demonstrate a novel, non-cell autonomous function of LRP1 in cell-cell signaling.
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Affiliation(s)
- He Meng
- Department of Neurology, University of Michigan, Ann Arbor, Michigan 48109-5622, USA
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26
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Tossidou I, Teng B, Menne J, Shushakova N, Park JK, Becker JU, Modde F, Leitges M, Haller H, Schiffer M. Podocytic PKC-alpha is regulated in murine and human diabetes and mediates nephrin endocytosis. PLoS One 2010; 5:e10185. [PMID: 20419132 PMCID: PMC2855708 DOI: 10.1371/journal.pone.0010185] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Accepted: 03/23/2010] [Indexed: 11/28/2022] Open
Abstract
Background Microalbuminuria is an early lesion during the development of diabetic nephropathy. The loss of high molecular weight proteins in the urine is usually associated with decreased expression of slit diaphragm proteins. Nephrin, is the major component of the glomerular slit diaphragm and loss of nephrin has been well described in rodent models of experimental diabetes as well as in human diabetic nephropathy. Methodology/Principal Findings In this manuscript we analyzed the role of PKC-alpha (PKCα) on endocytosis of nephrin in podocytes. We found that treatment of diabetic mice with a PKCα-inhibitor (GÖ6976) leads to preserved nephrin expression and reduced proteinuria. In vitro, we found that high glucose stimulation would induce PKCα protein expression in murine and human podocytes. We can demonstrate that PKCα mediates nephrin endocytosis in podocytes and that overexpression of PKCα leads to an augmented endocytosis response. After PKC-activation, we demonstrate an inducible association of PKCα, PICK1 and nephrin in podocytes. Moreover, we can demonstrate a strong induction of PKCα in podocytes of patients with diabetic nephropathy. Conclusions/Significance We therefore conclude that activation of PKCα is a pathomechanistic key event during the development of diabetic nephropathy. PKCα is involved in reduction of nephrin surface expression and therefore PKCα inhibition might be a novel target molecule for anti-proteinuric therapy.
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Affiliation(s)
- Irini Tossidou
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Beina Teng
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Jan Menne
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Nelli Shushakova
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Joon-Keun Park
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Jan U. Becker
- Department of Pathology, Hannover Medical School, Hannover, Germany
| | - Friedrich Modde
- Department of Pathology, Hannover Medical School, Hannover, Germany
| | - Michael Leitges
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
- The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway
| | - Hermann Haller
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Mario Schiffer
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
- * E-mail:
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Reekmans SM, Pflanzner T, Gordts PLSM, Isbert S, Zimmermann P, Annaert W, Weggen S, Roebroek AJM, Pietrzik CU. Inactivation of the proximal NPXY motif impairs early steps in LRP1 biosynthesis. Cell Mol Life Sci 2010; 67:135-45. [PMID: 19856143 PMCID: PMC11115674 DOI: 10.1007/s00018-009-0171-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 09/24/2009] [Accepted: 10/05/2009] [Indexed: 11/25/2022]
Abstract
The proximal NPXY and distal NPXYXXL motifs in the intracellular domain of LRP1 play an important role in regulation of the function of the receptor. The impact of single and double inactivating knock-in mutations of these motifs on receptor maturation, cell surface expression, and ligand internalization was analyzed in mutant and control wild-type mice and MEFs. Single inactivation of the proximal NPXY or in combination with inactivation of the distal NPXYXXL motif are both shown to be associated with an impaired maturation and premature proteasomal degradation of full-length LRP1. Therefore, only a small mature LRP1 pool is able to reach the cell surface resulting indirectly in severe impairment of ligand internalization. Single inactivation of the NPXYXXL motif revealed normal maturation, but direct impairment of ligand internalization. In conclusion, the proximal NPXY motif proves to be essential for early steps in the LRP1 biosynthesis, whereas NPXYXXL appears rather relevant for internalization.
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Affiliation(s)
- Sara M. Reekmans
- Laboratory for Experimental Mouse Genetics, Center for Human Genetics, KU Leuven, Herestraat 49, bus 602, 3000 Leuven, Belgium
- Laboratory for Experimental Mouse Genetics, Department of Molecular and Developmental Genetics, VIB, Leuven, Belgium
| | - Thorsten Pflanzner
- Molecular Neurodegeneration, Department of Physiological Chemistry and Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Duesbergweg 6, 55099 Mainz, Germany
| | - Philip L. S. M. Gordts
- Laboratory for Experimental Mouse Genetics, Center for Human Genetics, KU Leuven, Herestraat 49, bus 602, 3000 Leuven, Belgium
- Laboratory for Experimental Mouse Genetics, Department of Molecular and Developmental Genetics, VIB, Leuven, Belgium
| | - Simone Isbert
- Molecular Neurodegeneration, Department of Physiological Chemistry and Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Duesbergweg 6, 55099 Mainz, Germany
| | - Pascale Zimmermann
- Laboratory for Signal Integration in Cell Fate Decision, Center for Human Genetics, KU Leuven, Leuven, Belgium
| | - Wim Annaert
- Laboratory of Membrane Trafficking, Center for Human Genetics, KU Leuven, Leuven, Belgium
- Laboratory of Membrane Trafficking, Department of Molecular and Developmental Genetics, VIB, Leuven, Belgium
| | - Sascha Weggen
- Department of Neuropathology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Anton J. M. Roebroek
- Laboratory for Experimental Mouse Genetics, Center for Human Genetics, KU Leuven, Herestraat 49, bus 602, 3000 Leuven, Belgium
- Laboratory for Experimental Mouse Genetics, Department of Molecular and Developmental Genetics, VIB, Leuven, Belgium
| | - Claus U. Pietrzik
- Molecular Neurodegeneration, Department of Physiological Chemistry and Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Duesbergweg 6, 55099 Mainz, Germany
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28
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Fang L, Garuti R, Kim BY, Wade JB, Welling PA. The ARH adaptor protein regulates endocytosis of the ROMK potassium secretory channel in mouse kidney. J Clin Invest 2009; 119:3278-89. [PMID: 19841541 DOI: 10.1172/jci37950] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 08/26/2009] [Indexed: 11/17/2022] Open
Abstract
Renal outer medullary potassium (ROMK) channels are exquisitely regulated to adjust renal potassium excretion and maintain potassium balance. Clathrin-dependent endocytosis plays a critical role, limiting urinary potassium loss in potassium deficiency. In renal disease, aberrant ROMK endocytosis may contribute to potassium retention and hyperkalemia. Previous work has indicated that ROMK endocytosis is stimulated by with-no-lysine (WNK) kinases, but the endocytotic signal and the internalization machinery have not been defined. Here, we found that ROMK bound directly to the clathrin adaptor molecule autosomal recessive hypercholesterolemia (ARH), and this interaction was mediated by what we believe to be a novel variant of the canonical "NPXY" endocytotic signal, YxNPxFV. ARH recruits ROMK to clathrin-coated pits for constitutive and WNK1-stimuated endocytosis, and ARH knockdown decreased basal rates of ROMK endocytosis, in a heterologous expression system, COS-7 cells. We found that ARH was predominantly expressed in the distal nephron where it coimmunoprecipitated and colocalized with ROMK. In mice, the abundance of kidney ARH protein was modulated by dietary potassium and inversely correlated with changes in ROMK. Furthermore, ARH-knockout mice exhibited an altered ROMK response to potassium intake. These data suggest that ARH marks ROMK for clathrin-dependent endocytosis, in concert with the demands of potassium homeostasis.
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Affiliation(s)
- Liang Fang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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29
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Shiroshima T, Oka C, Kawaichi M. Identification of LRP1B-interacting proteins and inhibition of protein kinase Calpha-phosphorylation of LRP1B by association with PICK1. FEBS Lett 2008; 583:43-8. [PMID: 19071120 DOI: 10.1016/j.febslet.2008.11.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 11/09/2008] [Accepted: 11/18/2008] [Indexed: 11/30/2022]
Abstract
Recent studies show LDL receptor-related protein 1B, LRP1B as a transducer of extracellular signals. Here, we identify six interacting partners of the LRP1B cytoplasmic region by yeast two-hybrid screen and confirmed their in vivo binding by immunoprecipitation. One of the partners, PICK1 recognizes the C-terminus of LRP1B and LRP1. The cytoplasmic domains of LRP1B are phosphorylated by PKCalpha about 100 times more efficiently than LRP1. Binding of PICK1 inhibits phosphorylation of LRP1B, but does not affect LRP1 phosphorylation. This study presents the possibility that LRP1B participates in signal transduction which PICK1 may regulate by inhibiting PKCalpha phosphorylation of LRP1B.
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Affiliation(s)
- Tomoko Shiroshima
- Division of Gene Function in Animals, Nara Institute of Science and Technology, Takayama, Ikoma, Nara, Japan
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30
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Insulin stimulates hepatic low density lipoprotein receptor-related protein 1 (LRP1) to increase postprandial lipoprotein clearance. Atherosclerosis 2008; 204:105-11. [PMID: 18834984 DOI: 10.1016/j.atherosclerosis.2008.07.046] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 07/28/2008] [Accepted: 07/30/2008] [Indexed: 01/09/2023]
Abstract
BACKGROUND While the role of insulin in glucose uptake and its aberration in diabetes are well established, the effect of insulin on lipoprotein clearance in the postprandial phase is not yet fully understood. The dietary lipids are carried in chylomicron remnants (CR) which are taken up into the liver mainly via LDLR-related protein 1 (LRP1). In this study, the effect of insulin on LRP1-mediated hepatic CR uptake was investigated. METHODS The study was based on determining the subcellular localisation of LRP1 by subcellular fractionation and immunofluorescence microscopy and correlating those findings with the hepatic uptake of fluorescently or radioactively labelled LRP1-specific ligands and CR in hepatoma cells, primary hepatocytes and mouse models. RESULTS AND CONCLUSION In vitro and in vivo, insulin stimulated the translocation of hepatic LRP1 from intracellular vesicles to the plasma membrane, which correlates with an increased uptake of LRP1-specific ligands. In wild-type mice, a glucose-induced insulin response increased the hepatic uptake of LRP1 ligands while in leptin-deficient obese mice (ob/ob), which are characterised by hepatic insulin resistance, insulin-inducible LRP1 ligand uptake was abolished. Finally, upon hepatic LRP1 knockdown, insulin no longer significantly enhanced CR uptake into the liver. The insulin-induced LRP1-mediated CR uptake, as demonstrated here, suggests that impaired hepatic LRP1 translocation can contribute to the postprandial lipaemia in insulin resistance.
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31
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Lillis AP, Van Duyn LB, Murphy-Ullrich JE, Strickland DK. LDL receptor-related protein 1: unique tissue-specific functions revealed by selective gene knockout studies. Physiol Rev 2008; 88:887-918. [PMID: 18626063 DOI: 10.1152/physrev.00033.2007] [Citation(s) in RCA: 520] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The LDL receptor-related protein (originally called LRP, but now referred to as LRP1) is a large endocytic receptor that is widely expressed in several tissues. LRP1 is a member of the LDL receptor family that plays diverse roles in various biological processes including lipoprotein metabolism, degradation of proteases, activation of lysosomal enzymes, and cellular entry of bacterial toxins and viruses. Deletion of the LRP1 gene leads to lethality in mice, revealing a critical, but as of yet, undefined role in development. Tissue-specific gene deletion studies reveal an important contribution of LRP1 in the vasculature, central nervous system, macrophages, and adipocytes. Three important properties of LRP1 dictate its diverse role in physiology: 1) its ability to recognize more than 30 distinct ligands, 2) its ability to bind a large number of cytoplasmic adaptor proteins via determinants located on its cytoplasmic domain in a phosphorylation-specific manner, and 3) its ability to associate with and modulate the activity of other transmembrane receptors such as integrins and receptor tyrosine kinases.
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Affiliation(s)
- Anna P Lillis
- Center for Vascular and Inflammatory Diseases and Department of Surgery and Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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32
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Lillis AP, Greenlee MC, Mikhailenko I, Pizzo SV, Tenner AJ, Strickland DK, Bohlson SS. Murine low-density lipoprotein receptor-related protein 1 (LRP) is required for phagocytosis of targets bearing LRP ligands but is not required for C1q-triggered enhancement of phagocytosis. THE JOURNAL OF IMMUNOLOGY 2008; 181:364-73. [PMID: 18566402 DOI: 10.4049/jimmunol.181.1.364] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
C1q and members of the defense collagen family are pattern recognition molecules that bind to pathogens and apoptotic cells and trigger a rapid enhancement of phagocytic activity. Candidate phagocytic cell receptors responsible for the enhancement of phagocytosis by defense collagens have been proposed but not yet discerned. Engagement of phagocyte surface-associated calreticulin in complex with the large endocytic receptor, low-density lipoprotein receptor-related protein 1 (LRP/CD91), by defense collagens has been suggested as one mechanism governing enhanced ingestion of C1q-coated apoptotic cells. To investigate this possibility, macrophages were derived from transgenic mice genetically deficient in LRP resulting from tissue-specific loxP/Cre recombination. LRP-deficient macrophages were impaired in their ability to ingest beads coated with an LRP ligand when compared with LRP-expressing macrophages, confirming for the first time that LRP participates in phagocytosis. When LRP-deficient and -expressing macrophages were plated on C1q-coated slides, they demonstrated equivalently enhanced phagocytosis of sheep RBC suboptimally opsonized with IgG or complement, compared with cells plated on control protein. In addition, LRP-deficient and -expressing macrophages ingested equivalent numbers of apoptotic Jurkat cells in the presence and absence of serum. Both LRP-deficient and -expressing macrophages ingested fewer apoptotic cells when incubated in the presence of C1q-deficient serum compared with normal mouse serum, and the addition of purified C1q reconstituted uptake to control serum levels. These studies demonstrate a direct contribution of LRP to phagocytosis and indicate that LRP is not required for the C1q-triggered enhancement of phagocytosis, suggesting that other, still undefined, receptor(s) exist to mediate this important innate immune function.
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Affiliation(s)
- Anna P Lillis
- Center for Vascular and Inflammatory Diseases and Department of Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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33
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Gaultier A, Arandjelovic S, Li X, Janes J, Dragojlovic N, Zhou GP, Dolkas J, Myers RR, Gonias SL, Campana WM. A shed form of LDL receptor-related protein-1 regulates peripheral nerve injury and neuropathic pain in rodents. J Clin Invest 2008; 118:161-72. [PMID: 18060043 DOI: 10.1172/jci32371] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 10/03/2007] [Indexed: 12/11/2022] Open
Abstract
Injury to the peripheral nervous system (PNS) initiates a response controlled by multiple extracellular mediators, many of which contribute to the development of neuropathic pain. Schwann cells in an injured nerve demonstrate increased expression of LDL receptor-related protein-1 (LRP1), an endocytic receptor for diverse ligands and a cell survival factor. Here we report that a fragment of LRP1, in which a soluble or shed form of LRP1 with an intact alpha-chain (sLRP-alpha), was shed by Schwann cells in vitro and in the PNS after injury. Injection of purified sLRP-alpha into mouse sciatic nerves prior to chronic constriction injury (CCI) inhibited p38 MAPK activation (P-p38) and decreased expression of TNF-alpha and IL-1beta locally. sLRP-alpha also inhibited CCI-induced spontaneous neuropathic pain and decreased inflammatory cytokine expression in the spinal dorsal horn, where neuropathic pain processing occurs. In cultures of Schwann cells, astrocytes, and microglia, sLRP-alpha inhibited TNF-alpha-induced activation of p38 MAPK and ERK/MAPK. The activity of sLRP-alpha did not involve TNF-alpha binding, but rather glial cell preconditioning, so that the subsequent response to TNF-alpha was inhibited. Our results show that sLRP-alpha is biologically active and may attenuate neuropathic pain. In the PNS, the function of LRP1 may reflect the integrated activities of the membrane-anchored and shed forms of LRP1.
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Affiliation(s)
- Alban Gaultier
- Department of Pathology, UCSD School of Medicine, La Jolla, California 92093-0629, USA
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Lakshmana MK, Chen E, Yoon IS, Kang DE. C-terminal 37 residues of LRP promote the amyloidogenic processing of APP independent of FE65. J Cell Mol Med 2008; 12:2665-74. [PMID: 18373737 PMCID: PMC2864086 DOI: 10.1111/j.1582-4934.2008.00320.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The major defining pathological hallmark of Alzheimer's disease (AD) is the accumulation of amyloid beta protein (Abeta), a small peptide derived from beta- and gamma-secretase cleavages of the amyloid precursor protein (APP). Recent studies have shown that the Low-density lipoprotein receptor-related protein (LRP) plays a pivotal role in the trafficking of APP and generation of Abeta. In particular, we recently showed that the soluble cytoplasmic tail of LRP (LRP-ST) without a membrane tether was sufficient to promote Abeta generation. In this study, we demonstrate that the last 37 residues of LRP cytoplasmic tail (LRP-C37) lacking the NPxY motifs and FE65 binding mediate the core pro-amyloidogenic activity of LRP-ST. Moreover, we show that the conserved dileucine motif within the LRP-C37 region is a key determinant of its Abeta promoting activity. Finally, results from a yeast two-hybrid screen using LRP-C37 region as bait reveal four new LRP-binding proteins implicated in intracellular signalling and membrane protein trafficking. Our findings indicate that the LRP-C37 sequence represents a new protein-binding domain that may be useful as a therapeutic target and tool to lower Abeta generation in AD.
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Affiliation(s)
- Madepalli K Lakshmana
- Department of Neurosciences, University of California, San Diego, Gilman Drive, La Jolla, CA 92093, USA
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35
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Ahmad I, Hoessli DC, Walker-Nasir E, Choudhary MI, Rafik SM, Shakoori AR. Phosphorylation and glycosylation interplay: protein modifications at hydroxy amino acids and prediction of signaling functions of the human beta3 integrin family. J Cell Biochem 2007; 99:706-18. [PMID: 16676352 DOI: 10.1002/jcb.20814] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Protein functions are determined by their three-dimensional structures and the folded 3-D structure is in turn governed by the primary structure and post-translational modifications the protein undergoes during synthesis and transport. Defining protein functions in vivo in the cellular and extracellular environments is made very difficult in the presence of other molecules. However, the modifications taking place during and after protein folding are determined by the modification potential of amino acids and not by the primary structure or sequence. These post-translational modifications, like phosphorylation and O-linked N-acetylglucosamine (O-GlcNAc) modifications, are dynamic and result in temporary conformational changes that regulate many functions of the protein. Computer-assisted studies can help determining protein functions by assessing the modification potentials of a given protein. Integrins are important membrane receptors involved in bi-directional (outside-in and inside-out) signaling events. The beta3 integrin family, including, alpha(IIb)beta3 and alpha(v)beta3, has been studied for its role in platelet aggregation during clot formation and clot retraction based on hydroxyl group modification by phosphate and GlcNAc on Ser, Thr, or Tyr and their interplay on Ser and Thr in the cytoplasmic domain of the beta3 subunit. An antagonistic role of phosphate and GlcNAc interplay at Thr758 for controlling both inside-out and outside-in signaling events is proposed. Additionally, interplay of GlcNAc and phosphate at Ser752 has been proposed to control activation and inactivation of integrin-associated Src kinases. This study describes the multifunctional behavior of integrins based on their modification potential at hydroxyl groups of amino acids as a source of interplay.
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Affiliation(s)
- Ishtiaq Ahmad
- Institute of Molecular Sciences and Bioinformatics, Lahore, Pakistan
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36
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Yuseff MI, Farfan P, Bu G, Marzolo MP. A cytoplasmic PPPSP motif determines megalin's phosphorylation and regulates receptor's recycling and surface expression. Traffic 2007; 8:1215-30. [PMID: 17555532 DOI: 10.1111/j.1600-0854.2007.00601.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Megalin is a large endocytic receptor expressed at the apical surface of several absorptive epithelia. It binds multiple ligands including apolipoproteins, vitamin and hormone carrier proteins and signaling molecules such as parathyroid hormone and the morphogen sonic hedgehog. An important characteristic of megalin is its high endocytic activity, which is mediated by tyrosine-based endocytic motifs within the receptor's cytoplasmic tail. This domain also harbors several putative consensus phosphorylation motifs for protein kinase (PK) C and casein kinase-II and one consensus motif for PKA and glycogen synthase kinase-3 (GSK3). Here we report that the cytoplasmic domain of megalin is constitutively phosphorylated depending on the integrity of a PPPSP motif, a putative GSK3 site, with a minor participation of the other phosphorylation motifs. Mutation of the serine residue within the PPPSP motif as well as blocking GSK3 activity, with two different inhibitors, significantly decreased the phosphorylation levels of the receptor. Both the megalin PPPAP mutant and the underphosphorylated wild-type receptor, by inhibition of GSK3 activity, were more expressed at the cell surface and more efficiently recycled, but they were not inhibited in their initial endocytosis rates. Altogether, these results show that the PPPSP motif and the GSK3 activity are critical to allow megalin phosphorylation and also negatively regulate the receptor's recycling.
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Affiliation(s)
- María Isabel Yuseff
- FONDAP Center for Cell Regulation and Pathology (CRCP), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile and MIFAB, Santiago, Chile
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37
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Hayashi H, Campenot RB, Vance DE, Vance JE. Apolipoprotein E-containing lipoproteins protect neurons from apoptosis via a signaling pathway involving low-density lipoprotein receptor-related protein-1. J Neurosci 2007; 27:1933-41. [PMID: 17314289 PMCID: PMC6673537 DOI: 10.1523/jneurosci.5471-06.2007] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Apolipoprotein E (apoE)-containing lipoproteins (LPs) are secreted by glia and play important roles in lipid homeostasis in the CNS. Glia-derived LPs also promote synaptogenesis and stimulate axon growth of CNS neurons. Here, we provide evidence that glia-derived LPs protect CNS neurons from apoptosis by a receptor-mediated signaling pathway. The protective effect was greater for apolipoprotein E3 than for apolipoprotein E4, the expression of which is a risk factor for Alzheimer's disease. The anti-apoptotic effect of LPs required the association of apolipoprotein E with lipids but did not require cholesterol. Apoptosis was not prevented by lipids alone or by apoA1- or apoJ-containing lipoproteins. The prevention of neuronal apoptosis was initiated after the binding of LPs to the low-density lipoprotein receptor-related protein (LRP), a multifunctional receptor of the low-density lipoprotein receptor family. We showed that inhibition of LRP activation, by treatment of neurons with receptor-associated protein or anti-LRP antibodies, or by LRP gene-silencing experiments, reduced the protective effect of LPs. Furthermore, another LRP ligand, alpha2-macroglobulin, also protected the neurons from apoptosis. After binding to LRP, LPs initiate a signaling pathway that involves activation of protein kinase Cdelta and inactivation of glycogen synthase kinase-3beta. These findings indicate the potential for using glial lipoproteins or an activator of the LRP signaling pathway for treatment for neurodegenerative disorders such as Alzheimer's disease.
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Affiliation(s)
- Hideki Hayashi
- Group on Molecular and Cell Biology of Lipids and
- Departments of Medicine
| | | | - Dennis E. Vance
- Group on Molecular and Cell Biology of Lipids and
- Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
| | - Jean E. Vance
- Group on Molecular and Cell Biology of Lipids and
- Departments of Medicine
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38
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Caratù G, Allegra D, Bimonte M, Schiattarella GG, D'Ambrosio C, Scaloni A, Napolitano M, Russo T, Zambrano N. Identification of the Ligands of Protein Interaction Domains through a Functional Approach. Mol Cell Proteomics 2007; 6:333-45. [PMID: 17124247 DOI: 10.1074/mcp.m600289-mcp200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The identification of protein-protein interaction networks has often given important information about the functions of specific proteins and on the cross-talk among metabolic and regulatory pathways. The availability of entire genome sequences has rendered feasible the systematic screening of collections of proteins, often of unknown function, aimed to find the cognate ligands. Once identified by genetic and/or biochemical approaches, the interaction between two proteins should be validated in the physiologic environment. Herein we describe an experimental strategy to screen collections of protein-protein interaction domains to find and validate candidate interactors. The approach is based on the assumption that the overexpression in cultured cells of protein-protein interaction domains, isolated from the context of the whole protein, could titrate the endogenous ligand and, in turn, exert a dominant negative effect. The identification of the ligand could provide us with a tool to check the relevance of the interaction because the contemporary overexpression of the isolated domain and of its ligand could rescue the dominant negative phenotype. We explored this approach by analyzing the possible dominant negative effects on the cell cycle progression of a collection of phosphotyrosine binding (PTB) domains of human proteins. Of 47 PTB domains, we found that the overexpression of 10 of them significantly interfered with the cell cycle progression of NIH3T3 cells. Four of them were used as baits to identify the cognate interactors. Among these proteins, CARM1, interacting with the PTB domain of RabGAP1, and EF1alpha, interacting with RGS12, were able to rescue the block of the cell cycle induced by the isolated PTB domain of the partner protein, thus confirming in vivo the relevance of the interaction. These results suggest that the described approach can be used for the systematic screening of the ligands of various protein-protein interaction domains also by using different biological assays.
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Affiliation(s)
- Ginevra Caratù
- CEINGE Biotecnologie Avanzate, Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, 80131 Napoli, Italy
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39
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Polavarapu R, Gongora MC, Yi H, Ranganthan S, Lawrence DA, Strickland D, Yepes M. Tissue-type plasminogen activator-mediated shedding of astrocytic low-density lipoprotein receptor-related protein increases the permeability of the neurovascular unit. Blood 2006; 109:3270-8. [PMID: 17170123 PMCID: PMC1852247 DOI: 10.1182/blood-2006-08-043125] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The low-density lipoprotein receptor-related protein (LRP) is a member of the LDL receptor gene family that binds several ligands, including tissue-type plasminogen activator (tPA). tPA is found in blood, where its primary function is as a thrombolytic enzyme, and in the central nervous system where it mediates events associated with cell death. Cerebral ischemia induces changes in the neurovascular unit (NVU) that result in brain edema. We investigated whether the interaction between tPA and LRP plays a role in the regulation of the permeability of the NVU during cerebral ischemia. We found that the ischemic insult induces shedding of LRP's ectodomain from perivascular astrocytes into the basement membrane. This event associates with the detachment of astrocytic end-feet processes and the formation of areas of perivascular edema. The shedding of LRP's ectodomain is significantly decreased in tPA deficient (tPA(-/-)) mice, is increased by incubation with tPA, and is inhibited by the receptor-associated protein (RAP). Furthermore, treatment with either RAP or anti-LRP IgG results in a faster recovery of motor activity and protection of the integrity of the NVU following middle cerebral artery occlusion (MCAO). Together, these results implicate tPA/LRP interactions as key regulators of the integrity of the NVU.
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Affiliation(s)
- Rohini Polavarapu
- Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
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40
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Rege TA, Pallero MA, Gomez C, Grenett HE, Murphy-Ullrich JE, Hagood JS. Thy-1, via its GPI anchor, modulates Src family kinase and focal adhesion kinase phosphorylation and subcellular localization, and fibroblast migration, in response to thrombospondin-1/hep I. Exp Cell Res 2006; 312:3752-67. [PMID: 17027000 DOI: 10.1016/j.yexcr.2006.07.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 07/07/2006] [Accepted: 07/11/2006] [Indexed: 11/27/2022]
Abstract
Normal fibroblast subpopulations have differential surface expression of the GPI-linked raft protein Thy-1, which correlates with differences in cellular adhesion and migration in vitro. Thrombospondin-1 (TSP-1) induces an intermediate state of adhesion in fibroblasts and other cells which facilitates migration. TSP-1 and the hep I peptide derived from the amino-terminal/heparin-binding domain of TSP-1 induce disassembly of cellular focal adhesions. Our lab previously reported that the induction of focal adhesion disassembly in fibroblasts by TSP-1 or by hep I requires surface expression of Thy-1, as well as lipid raft integrity and Src family kinase (SFK) signaling. We now report that TSP-1/hep I-induced fibroblast migration requires Thy-1 expression and FAK phosphorylation, and that following TSP-1/hep I stimulation, Thy-1 associates with FAK and SFK in a lipid raft-dependent manner. Furthermore, the GPI anchor of Thy-1, which localizes the protein to specific lipid raft microdomains, is necessary for hep I-induced FAK and SFK phosphorylation, focal adhesion disassembly, and migration. This is the first report of an association between Thy-1 and FAK. Thy-1 modulates SFK and FAK phosphorylation and subcellular localization, promoting focal adhesion disassembly and migration in fibroblasts, following exposure to TSP-1/hep I.
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Affiliation(s)
- Tanya A Rege
- Department of Cell Biology, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
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41
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Peltan ID, Thomas AV, Mikhailenko I, Strickland DK, Hyman BT, von Arnim CAF. Fluorescence lifetime imaging microscopy (FLIM) detects stimulus-dependent phosphorylation of the low density lipoprotein receptor-related protein (LRP) in primary neurons. Biochem Biophys Res Commun 2006; 349:24-30. [PMID: 16930548 DOI: 10.1016/j.bbrc.2006.07.212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Accepted: 07/19/2006] [Indexed: 10/24/2022]
Abstract
The low-density lipoprotein receptor-related protein (LRP) is a large, endocytic receptor involved in intracellular signalling. LRP acts as a co-receptor with the PDGF-receptor (PDGF-r) for platelet-derived growth factor (PDGF). PDGF-r and Src-kinases induce tyrosine-phosphorylation of LRP. We used fluorescence lifetime imaging microscopy (FLIM) to specifically detect LRP phosphorylation, measure its extent and localization in intact cells, and assess its effects upon LRP-APP interaction. Robust phosphorylation of LRP throughout the cell was observed after overexpression of Src-kinase. This depended on LRP's distal NPXY domain. By contrast, activation of the PDGF-r resulted in phosphorylation of the subpopulation of LRP at or near the cell surface. PDGF activation triggered phosphorylation of endogenous LRP in primary neurons. LRP is also a trafficking receptor for the Alzheimer-related molecule amyloid-precursor-protein (APP). PDGF stimulation did not affect LRP-APP interactions. This approach allows exquisite subcellular resolution of specific LRP post-translational changes and protein-protein interactions of endogenous proteins in intact cells.
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Affiliation(s)
- Ithan D Peltan
- Alzheimer's Disease Research Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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Kiss RS, Ma Z, Nakada-Tsukui K, Brugnera E, Vassiliou G, McBride HM, Ravichandran KS, Marcel YL. The lipoprotein receptor-related protein-1 (LRP) adapter protein GULP mediates trafficking of the LRP ligand prosaposin, leading to sphingolipid and free cholesterol accumulation in late endosomes and impaired efflux. J Biol Chem 2006; 281:12081-92. [PMID: 16497666 DOI: 10.1074/jbc.m600621200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
One of the conserved functional pathways linked to engulfment of apoptotic corpses involves two membrane proteins low density lipoprotein receptor-related protein-1 (LRP) and ABCA1 and the LRP adapter protein GULP. Because LRP and ABCA1 play roles in cellular lipid trafficking and efflux, here we addressed whether the third member, the LRP adapter protein GULP, also affects cellular lipid transport. Several lines of evidence show that overexpression of GULP causes glycosphingolipid and free cholesterol accumulation in the late endosome/lysosome compartment that is accompanied by down-regulation of ABCA1 and decreased efflux. Conversely, knockdown of endogenous GULP expression promoted cholesterol flux through the late endosomes and up-regulation of ABCA1, even in the context of a disease state such as Niemann-Pick Type C disease. Mechanistically, we were able to show that trafficking of the LRP ligands alpha2-macroglobulin and prosaposin, a protein cofactor necessary for glycosphingolipid degradation, are impaired in cells expressing full-length GULP protein, resulting in glycosphingolipid and free cholesterol accumulation in the late endosome/lysosome compartment. On the other hand, knockdown of endogenous GULP results in enhanced targeting of prosaposin and enhanced clearance of glycosphingolipids and cholesterol from the late endosomes. Taken together, these data reveal that GULP/LRP/ABCA1 represents a triad of molecules involved in engulfment and cellular lipid homeostasis.
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Affiliation(s)
- Robert S Kiss
- Lipoprotein and Atherosclerosis Research Group, Department of Pathology and Laboratory Medicine, University of Ottawa Heart Institute, Ottawa K1Y 4W7, Canada
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43
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Roebroek AJM, Reekmans S, Lauwers A, Feyaerts N, Smeijers L, Hartmann D. Mutant Lrp1 knock-in mice generated by recombinase-mediated cassette exchange reveal differential importance of the NPXY motifs in the intracellular domain of LRP1 for normal fetal development. Mol Cell Biol 2006; 26:605-16. [PMID: 16382151 PMCID: PMC1346909 DOI: 10.1128/mcb.26.2.605-616.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lrp1 knock-in mice carrying either a wild-type allele or three different mutated alleles encoding the multifunctional endocytic receptor LRP1 were generated by recombinase-mediated cassette exchange (RMCE). Reinsertion by RMCE of a wild-type allele led to a normal pattern and level of gene expression and a completely normal phenotype, indicating that the RMCE procedure itself is neutral with respect to the function of the gene locus. In contrast, reinsertion of mutated LRP1 alleles carrying either inactivating mutations in the proximal NPXY motif (NPTY-->AATA) of the cytoplasmic domain or in the furin cleavage site (RHRR-->AHAA) caused distinctive liver phenotypes: respectively, either a late fetal destruction of the organ causing perinatal death or a selective enlargement of von-Kupffer cell lysosomes reminiscent of a mild lysosomal storage without an apparent negative effect on animal survival. Notably, mutation of the distal NPXY motif overlapping with an YXXL motif (NPVYATL-->AAVAATL) did not cause any obvious pathological effect. The mutations showed no effect on the LRP1 expression level; however, as expected, the proteolytic maturation of LRP1 into its two subunits was significantly impaired, although not completely abolished, in the furin cleavage mutant. These data demonstrate that RMCE is a reliable and efficient approach to generate multiple mutant knock-in alleles for in vivo functional analysis of individual domains or motifs of large multidomain proteins. Its application in Lrp1 reveals dramatically variant phenotypes, of which further characterization will definitively contribute to our understanding of the biology of this multifunctional receptor.
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Affiliation(s)
- Anton J M Roebroek
- Experimental Mouse Genetics, Center for Human Genetics, KU Leuven and Flanders Interuniversity Institute for Biotechnology, Herestraat 49, bus 602, B-3000 Leuven, Belgium.
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44
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Gaultier A, Salicioni AM, Arandjelovic S, Gonias SL. Regulation of the composition of the extracellular matrix by low density lipoprotein receptor-related protein-1: activities based on regulation of mRNA expression. J Biol Chem 2006; 281:7332-40. [PMID: 16407289 DOI: 10.1074/jbc.m511857200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Low density lipoprotein receptor-related protein-1 (LRP-1) is a catabolic receptor for extracellular matrix (ECM) structural proteins and for proteins that bind to ECM. LRP-1 also is implicated in integrin maturation. In this study, we applied a proteomics strategy to identify novel proteins involved in ECM modeling that are regulated by LRP-1. We show that LRP-1 deficiency in murine embryonic fibroblasts (MEFs) is associated with increased levels of type III collagen and pigment epithelium-derived factor, which accumulate in the substratum surrounding cells. The collagen receptor, uPAR-AP/Endo-180, is also increased in LRP-1-deficient MEFs. Human LRP-1 reversed the changes in protein expression associated with LRP-1 deficiency; however, the endocytic activity of LRP-1 was not involved. Instead, regulation occurred at the mRNA level. Inhibition of c-Jun amino-terminal kinase (JNK) blocked type III collagen expression in LRP-1-deficient MEFs, suggesting regulation of JNK activity as a mechanism by which LRP-1 controls mRNA expression. The ability of LRP-1 to regulate expression of the factors identified here suggests a role for LRP-1 in determining blood vessel structure and in angiogenesis.
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MESH Headings
- Animals
- Biotin/chemistry
- Cell Line
- Cell Membrane/metabolism
- Cloning, Molecular
- Collagen/chemistry
- Culture Media, Conditioned/metabolism
- Culture Media, Conditioned/pharmacology
- Electrophoresis, Gel, Two-Dimensional
- Electrophoresis, Polyacrylamide Gel
- Endocytosis
- Extracellular Matrix/metabolism
- Fibrinogen/chemistry
- Gene Expression Regulation
- Humans
- LDL-Receptor Related Proteins/metabolism
- Low Density Lipoprotein Receptor-Related Protein-1/metabolism
- Low Density Lipoprotein Receptor-Related Protein-1/physiology
- Mass Spectrometry
- Mice
- Microscopy, Fluorescence
- Neovascularization, Pathologic
- Phosphorylation
- Proteomics
- RNA, Messenger/metabolism
- Receptors, LDL/metabolism
- Receptors, LDL/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Surface Properties
- Tumor Suppressor Proteins/metabolism
- Tumor Suppressor Proteins/physiology
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Affiliation(s)
- Alban Gaultier
- Department of Pathology, School of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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Li X, Herz J, Monard D. Activation of ERK signaling upon alternative protease nexin-1 internalization mediated by syndecan-1. J Cell Biochem 2006; 99:936-51. [PMID: 16741952 DOI: 10.1002/jcb.20881] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Protease nexin-1 (PN-1), an inhibitor of serine proteases, contributes to tissue homeostasis and influences the behavior of some tumor cells. The internalization of PN-1 protease complexes is considered to be mediated by the low-density lipoprotein receptor related protein 1 (LRP1). In this study, both wild-type and LRP1-/- mouse embryonic fibroblasts (MEF) were shown to internalize PN-1. Receptor associated protein (RAP) interfered with PN-1 uptake only in wild-type MEF cells, indicating that another receptor mediates PN-1 uptake in the absence of LRP1. In LRP1-/- MEF cells, inhibitor sensitivity and kinetic values (t(1/2) at 45 min) of PN-1 uptake showed a similarity to syndecan-1-mediated endocytosis. In these cells, PN-1 uptake was increased by overexpression of full-length syndecan-1 and decreased by RNA interference targeting this proteoglycan. Most important, in contrast to PKA activation known to be triggered by LRP1-mediated internalization, our study shows that syndecan-1-mediated internalization of PN-1 stimulated the Ras-ERK signaling pathway.
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Affiliation(s)
- Xiaobiao Li
- Friedrich Miescher Institute for Biomedical Research, CH-4058, Basel, Switzerland
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Heeren J, Beisiegel U, Grewal T. Apolipoprotein E recycling: implications for dyslipidemia and atherosclerosis. Arterioscler Thromb Vasc Biol 2005; 26:442-8. [PMID: 16373604 DOI: 10.1161/01.atv.0000201282.64751.47] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
After receptor-mediated endocytosis, the intracellular fate of triglyceride-rich lipoproteins (TRLs) is far more complex than the classical degradation pathway of low-density lipoproteins. Once internalized, TRLs disintegrate in peripheral endosomes, followed by a differential sorting of TRL components. Although core lipids and apolipoprotein B are targeted to lysosomes, the majority of TRL-derived apolipoprotein E (apoE) remains in peripheral recycling endosomes. This pool of TRL-derived apoE is then mobilized by high-density lipoproteins (HDLs) or HDL-derived apoA-I to be recycled back to the plasma membrane, followed by apoE resecretion and the subsequent formation of apoE-containing HDL. The HDL-induced recycling of apoE is accompanied by cholesterol efflux and involves the internalization and targeting of HDL-derived apoA-I to endosomes containing both apoE and cholesterol. These findings point to a yet unknown intracellular link between TRL-derived apoE, cellular cholesterol transport, and HDL metabolism. Recent studies provide first evidence that impaired recycling of TRL-derived apoE4, but not apoE3, is associated with intracellular cholesterol accumulation, which might explain some well-documented effects of apoE4 on HDL metabolism. This review summarizes the current understanding of apoE recycling and its potential role in the regulation of plasma apoE levels in the postprandial state.
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Affiliation(s)
- Joerg Heeren
- Institute for Biochemistry and Molecular Biology II, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Lillis AP, Mikhailenko I, Strickland DK. Beyond endocytosis: LRP function in cell migration, proliferation and vascular permeability. J Thromb Haemost 2005; 3:1884-93. [PMID: 16102056 DOI: 10.1111/j.1538-7836.2005.01371.x] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The low-density lipoprotein (LDL) receptor related protein (LRP1 or LRP) is a large endocytic receptor widely expressed in several tissues and known to play roles in areas as diverse as lipoprotein metabolism, degradation of proteases, activation of lysosomal enzymes and cellular entry of bacterial toxins and viruses. This member of the LDL receptor superfamily is constitutively endocytosed from the membrane and recycled back to the cell surface. Its many functions were long thought to involve its ability to bind over 30 different ligands and deliver them to lysosomes for degradation. However, LRP has since been shown to interact with scaffolding and signaling proteins via its intracellular domain in a phosphorylation-dependent manner and to function as a co-receptor partnering with other cell surface or integral membrane proteins. This multi-talented receptor has been implicated in regulation of platelet derived growth factor receptor activity, integrin maturation and recycling, and focal adhesion disassembly. These functions may account for recent studies identifying LRP's role in protection of the vasculature, regulation of cell migration, and modulation of the integrity of the blood-brain barrier.
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Affiliation(s)
- A P Lillis
- Department of Surgery, University of Maryland School of Medicine, Rockville, MD 20855, USA
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Newton CS, Loukinova E, Mikhailenko I, Ranganathan S, Gao Y, Haudenschild C, Strickland DK. Platelet-derived growth factor receptor-beta (PDGFR-beta) activation promotes its association with the low density lipoprotein receptor-related protein (LRP). Evidence for co-receptor function. J Biol Chem 2005; 280:27872-8. [PMID: 15944146 DOI: 10.1074/jbc.m505410200] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the platelet-derived growth factor receptor-beta (PDGFR-beta) leads to tyrosine phosphorylation of the cytoplasmic domain of LRP and alters its association with adaptor and signaling proteins, such as Shc. The mechanism of the PDGF-induced LRP tyrosine phosphorylation is not well understood, especially since PDGF not only activates PDGF receptor but also binds directly to LRP. To gain insight into this mechanism, we used a chimeric receptor in which the ligand binding domain of the PDGFR-beta was replaced with that from the macrophage colony-stimulating factor (M-CSF) receptor, a highly related receptor tyrosine kinase of the same subfamily, but with different ligand specificity. Activation of the chimeric receptor upon the addition of M-CSF readily mediated the tyrosine phosphorylation of LRP. Since M-CSF is not recognized by LRP, these results indicated that growth factor binding to LRP is not necessary for this phosphorylation event. Using a panel of cytoplasmic domain mutants of the chimeric M-CSF/PDGFR-beta, we confirmed that the kinase domain of PDGFR-beta is absolutely required for LRP tyrosine phosphorylation but that PDGFR-beta-mediated activation of phosphatidylinositol 3-kinase, RasGAP, SHP-2, phospholipase C-gamma, and Src are not necessary for LRP tyrosine phosphorylation. To identify the cellular compartment where LRP and the PDGFR-beta may interact, we employed immunofluorescence and immunogold electron microscopy. In WI-38 fibroblasts, these two receptors co-localized in coated pits and endosomal compartments following PDGF stimulation. Further, phosphorylated forms of the PDGFR-beta co-immunoprecipitated with LRP following PDGF treatment. Together, these studies revealed close association between activated PDGFR-beta and LRP, suggesting that LRP functions as a co-receptor capable of modulating the signal transduction pathways initiated by the PDGF receptor from endosomes.
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Affiliation(s)
- Christopher S Newton
- Department of Surgery and Physiology, University of Maryland School of Medicine, 15601 Crabbs Branch Way, Rockville, Maryland 20855, USA
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