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Jaye S, Sandau US, McFarland TJ, Woltjer RL, Saugstad JA. A clathrin mediated endocytosis scaffolding protein, Intersectin 1, changes in an isoform, brain region, and sex specific manner in Alzheimer's disease. Front Neurosci 2024; 18:1426180. [PMID: 38915309 PMCID: PMC11195150 DOI: 10.3389/fnins.2024.1426180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 05/28/2024] [Indexed: 06/26/2024] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia and is characterized by the accumulation of amyloid-beta (Aβ) plaques and neurofibrillary Tau tangles in the brain. We previously identified a set of candidate AD microRNAs (miRNAs) in human cerebrospinal fluid (CSF) and used a target prediction pipeline to identify mRNAs and pathways that could potentially be regulated by the miRNAs. Of these pathways, clathrin mediated endocytosis (CME) was selected for further investigation. CME is altered in multiple brain cell types in AD and is implicated in early cellular phenotypes such as enlarged early endosomes and pathogenic processing of Aβ. However, a comprehensive evaluation of major CME hub proteins in humans with AD across multiple brain regions is lacking. Thus, we used immunoblots to evaluate human post-mortem AD and control (CTL) frontal cortex (FC; AD n = 22, CTL n = 23) and hippocampus (HP; AD n = 34, CTL n = 22) for changes in Intersectin 1 (ITSN1), Phosphatidylinositol Binding Clathrin Assembly Protein gene (PICALM), Clathrin Light Chain (CLT), FCH and Mu Domain Containing Endocytic Adaptor 1 (FCHO1), Adaptor Related Protein Complex 2 (AP2) Subunit Alpha 1 (AP2A1), and Dynamin 2 (DNM2). Of these, we found that in AD, ITSN1-long (ITSN1-L) was decreased in the FC of males and HP of females, while ITSN1-short was increased in the HP of both males and females. We further evaluated ITSN1-L levels in cortex (CTX) and HP of the 5xFAD mouse model of Aβ pathology at different timepoints during aging and disease progression by immunoblot (n = 5-8 per group). At 3 months, female 5xFAD exhibited an increase of ITSN1-L in CTX but a decrease at 6 and 9 months. Additionally, immunofluorescent staining of 5xFAD primary HP neurons showed an increase of ITSN1-L in matured 5xFAD neurons at 21 and 28 days in vitro. Together, our studies show that in AD, isoforms of ITSN1 change in a brain region-and sex-dependent manner. Further, changes in ITSN1-L are transient with levels increasing during early Aβ accumulation and decreasing during later progression. These findings suggest that ITSN1 expression, and consequently CME activity, may change depending on the stage of disease progression.
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Affiliation(s)
- Sierra Jaye
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Ursula S. Sandau
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Trevor J. McFarland
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Randy L. Woltjer
- Division of Neuropathology, Department of Pathology, Oregon Health and Science University, Portland, OR, United States
| | - Julie A. Saugstad
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, United States
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Qin S, Predescu DN, Patel M, Drazkowski P, Ganesh B, Predescu SA. Sex differences in the proliferation of pulmonary artery endothelial cells: implications for plexiform arteriopathy. J Cell Sci 2020; 133:133/9/jcs237776. [PMID: 32409569 DOI: 10.1242/jcs.237776] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 03/13/2020] [Indexed: 12/14/2022] Open
Abstract
The sex-biased disease pulmonary arterial hypertension (PAH) is characterized by the proliferation and overgrowth of dysfunctional pulmonary artery endothelial cells (PAECs). During inflammation associated with PAH, granzyme B cleaves intersectin-1 to produce N-terminal (EHITSN) and C-terminal (SH3A-EITSN) protein fragments. In a murine model of PAH, EHITSN triggers plexiform arteriopathy via p38-ELK1-c-Fos signaling. The SH3A-EITSN fragment also influences signaling, having dominant-negative effects on ERK1 and ERK2 (also known as MAPK3 and MAPK1, respectively). Using PAECs engineered to express tagged versions of EHITSN and SH3A-EITSN, we demonstrate that the two ITSN fragments increase both p38-ELK1 activation and the ratio of p38 to ERK1 and ERK2 activity, leading to PAEC proliferation, with female cells being more responsive than male cells. Furthermore, expression of EHITSN substantially upregulates the expression and activity of the long non-coding RNA Xist in female PAECs, which in turn upregulates the X-linked gene ELK1 and represses expression of krüppel-like factor 2 (KLF2). These events are recapitulated by the PAECs of female idiopathic PAH patients, and may account for their proliferative phenotype. Thus, upregulation of Xist could be an important factor in explaining sexual dimorphism in the proliferative response of PAECs and the imbalanced sex ratio of PAH.
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Affiliation(s)
- Shanshan Qin
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Dan N Predescu
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Monal Patel
- Division of Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Patrick Drazkowski
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Balaji Ganesh
- Division of Bioanalytics, Biophysics and Cytomics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Sanda A Predescu
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Rush University Medical Center, Chicago, IL 60612, USA
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Dergai O, Dergai M, Rynditch A. Ubiquitin-ligase AIP4 controls differential ubiquitination and stability of isoforms of the scaffold protein ITSN1. FEBS Lett 2018; 592:2259-2267. [PMID: 29851086 DOI: 10.1002/1873-3468.13118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/12/2018] [Accepted: 05/17/2018] [Indexed: 11/07/2022]
Abstract
At present, the role of ubiquitination of cargoes internalized from the plasma membrane is better understood than the consequences of ubiquitination of proteins comprising the endocytic machinery. Here, we show that the E3 ubiquitin ligase AIP4/ITCH contributes to the differential ubiquitination of isoforms of the endocytic scaffold protein intersectin1 (ITSN1). The major isoform ITSN1-s is monoubiquitinated, whereas the minor one, ITSN1-22a undergoes a combination of mono- and oligoubiquitination. The monoubiquitination is required for ITSN1-s stability, whereas the oligoubiquitination of ITSN1-22a causes its proteasomal degradation. This explains the observed low abundance of the minor isoform in cells. Thus, different modes of ubiquitination regulated by AIP4 have opposite effects on ITSN1 isoform stability.
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Affiliation(s)
- Oleksandr Dergai
- Institute of Molecular Biology and Genetics, The National Academy of Science of Ukraine, Kyiv, Ukraine
| | - Mykola Dergai
- Institute of Molecular Biology and Genetics, The National Academy of Science of Ukraine, Kyiv, Ukraine
| | - Alla Rynditch
- Institute of Molecular Biology and Genetics, The National Academy of Science of Ukraine, Kyiv, Ukraine
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Ioannou MS, Kulasekaran G, Fotouhi M, Morein JJ, Han C, Tse S, Nossova N, Han T, Mannard E, McPherson PS. Intersectin-s interaction with DENND2B facilitates recycling of epidermal growth factor receptor. EMBO Rep 2017; 18:2119-2130. [PMID: 29030480 DOI: 10.15252/embr.201744034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 11/09/2022] Open
Abstract
Epidermal growth factor (EGF) activates the EGF receptor (EGFR) and stimulates its internalization and trafficking to lysosomes for degradation. However, a percentage of EGFR undergoes ligand-independent endocytosis and is rapidly recycled back to the plasma membrane. Importantly, alterations in EGFR recycling are a common hallmark of cancer, and yet, our understanding of the machineries controlling the fate of endocytosed EGFR is incomplete. Intersectin-s is a multi-domain adaptor protein that is required for internalization of EGFR Here, we discover that intersectin-s binds DENND2B, a guanine nucleotide exchange factor for the exocytic GTPase Rab13, and this interaction promotes recycling of ligand-free EGFR to the cell surface. Intriguingly, upon EGF treatment, DENND2B is phosphorylated by protein kinase D and dissociates from intersectin-s, allowing for receptor targeting to degradation. Our study thus reveals a novel mechanism controlling the fate of internalized EGFR with important implications for cancer.
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Affiliation(s)
- Maria S Ioannou
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Gopinath Kulasekaran
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Maryam Fotouhi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Justin J Morein
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Chanshuai Han
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Sarah Tse
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Nadya Nossova
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Tony Han
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Erin Mannard
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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Jeganathan N, Predescu D, Predescu S. Intersectin-1s deficiency in pulmonary pathogenesis. Respir Res 2017; 18:168. [PMID: 28874189 PMCID: PMC5585975 DOI: 10.1186/s12931-017-0652-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 08/28/2017] [Indexed: 02/07/2023] Open
Abstract
Intersectin-1s (ITSN-1s), a multidomain adaptor protein, plays a vital role in endocytosis, cytoskeleton rearrangement and cell signaling. Recent studies have demonstrated that deficiency of ITSN-1s is a crucial early event in pulmonary pathogenesis. In lung cancer, ITSN-1s deficiency impairs Eps8 ubiquitination and favors Eps8-mSos1 interaction which activates Rac1 leading to enhanced lung cancer cell proliferation, migration and metastasis. Restoring ITSN-1s deficiency in lung cancer cells facilitates cytoskeleton changes favoring mesenchymal to epithelial transformation and impairs lung cancer progression. ITSN-1s deficiency in acute lung injury leads to impaired endocytosis which leads to ubiquitination and degradation of growth factor receptors such as Alk5. This deficiency is counterbalanced by microparticles which, via paracrine effects, transfer Alk5/TGFβRII complex to non-apoptotic cells. In the presence of ITSN-1s deficiency, Alk5-restored cells signal via Erk1/2 MAPK pathway leading to restoration and repair of lung architecture. In inflammatory conditions such as pulmonary artery hypertension, ITSN-1s full length protein is cleaved by granzyme B into EHITSN and SH3A-EITSN fragments. The EHITSN fragment leads to pulmonary cell proliferation via activation of p38 MAPK and Elk-1/c-Fos signaling. In vivo, ITSN-1s deficient mice transduced with EHITSN plasmid develop pulmonary vascular obliteration and plexiform lesions consistent with pathological findings seen in severe pulmonary arterial hypertension. These novel findings have significantly contributed to understanding the mechanisms and pathogenesis involved in pulmonary pathology. As demonstrated in these studies, genetically modified ITSN-1s expression mouse models will be a valuable tool to further advance our understanding of pulmonary pathology and lead to novel targets for treating these conditions.
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Affiliation(s)
| | - Dan Predescu
- Department of Pharmacology and Division of Pulmonary and Critical Care Medicine, Rush University, 1750 W. Harrison Street, 1415 Jelke, Chicago, IL, 60612, USA
| | - Sanda Predescu
- Department of Pharmacology and Division of Pulmonary and Critical Care Medicine, Rush University Medical Center and Rush Medical College, 1750 W. Harrison Street, 1535 Jelke, Chicago, IL, 60612, USA
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Intersectin 1 is a component of the Reelin pathway to regulate neuronal migration and synaptic plasticity in the hippocampus. Proc Natl Acad Sci U S A 2017; 114:5533-5538. [PMID: 28484035 DOI: 10.1073/pnas.1704447114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Brain development and function depend on the directed and coordinated migration of neurons from proliferative zones to their final position. The secreted glycoprotein Reelin is an important factor directing neuronal migration. Loss of Reelin function results in the severe developmental disorder lissencephaly and is associated with neurological diseases in humans. Reelin signals via the lipoprotein receptors very low density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2), but the exact mechanism by which these receptors control cellular function is poorly understood. We report that loss of the signaling scaffold intersectin 1 (ITSN1) in mice leads to defective neuronal migration and ablates Reelin stimulation of hippocampal long-term potentiation (LTP). Knockout (KO) mice lacking ITSN1 suffer from dispersion of pyramidal neurons and malformation of the radial glial scaffold, akin to the hippocampal lamination defects observed in VLDLR or ApoER2 mutants. ITSN1 genetically interacts with Reelin receptors, as evidenced by the prominent neuronal migration and radial glial defects in hippocampus and cortex seen in double-KO mice lacking ITSN1 and ApoER2. These defects were similar to, albeit less severe than, those observed in Reelin-deficient or VLDLR/ ApoER2 double-KO mice. Molecularly, ITSN1 associates with the VLDLR and its downstream signaling adaptor Dab1 to facilitate Reelin signaling. Collectively, these data identify ITSN1 as a component of Reelin signaling that acts predominantly by facilitating the VLDLR-Dab1 axis to direct neuronal migration in the cortex and hippocampus and to augment synaptic plasticity.
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Patel M, Predescu D, Bardita C, Chen J, Jeganathan N, Pritchard M, DiBartolo S, Machado R, Predescu S. Modulation of Intersectin-1s Lung Expression Induces Obliterative Remodeling and Severe Plexiform Arteriopathy in the Murine Pulmonary Vascular Bed. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:528-542. [PMID: 28068512 DOI: 10.1016/j.ajpath.2016.11.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 10/31/2016] [Accepted: 11/22/2016] [Indexed: 12/11/2022]
Abstract
Murine models of pulmonary arterial hypertension (PAH) that recapitulate the plexiform and obliterative arteriopathy seen in PAH patients and help in defining the molecular mechanisms involved are missing. Herein, we investigated whether intersectin-1s (ITSN) deficiency and prolonged lung expression of an ITSN fragment with endothelial cell (EC) proliferative potential (EHITSN), present in the lungs of PAH animal models and human patients, induce formation of plexiform/obliterative lesions and defined the molecular mechanisms involved. ITSN-deficient mice (knockout/heterozygous and knockdown) were subjected to targeted lung delivery of EHITSN via liposomes for 20 days. Immunohistochemistry and histological and morphometric analyses revealed a twofold increase in proliferative ECs and a 1.35-fold increase in proliferative α-smooth muscle actin-positive cells in the lungs of ITSN-deficient mice, transduced with the EHITSN relative to wild-type littermates. Treated mice developed severe medial wall hypertrophy, intima proliferation, and various forms of obliterative and plexiform-like lesions in pulmonary arteries, similar to PAH patients. Hemodynamic measurements indicated modest increases in the right ventricular systolic pressure and right ventricle hypertrophy. Transcriptional and protein assays of lung tissue indicated p38MAPK-dependent activation of Elk-1 transcription factor and increased expression of c-Fos gene. This unique murine model of PAH-like plexiform/obliterative arteriopathy induced via a two-hit pathophysiological mechanism without hypoxia provides novel druggable targets to ameliorate and, perhaps, reverse the EC plexiform phenotype in severe human PAH.
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Affiliation(s)
- Monal Patel
- Department of Pharmacology & Internal Medicine, Division of Pulmonary and Critical Care, Rush University Medical Center, Chicago, Illinois; Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Dan Predescu
- Department of Pharmacology & Internal Medicine, Division of Pulmonary and Critical Care, Rush University Medical Center, Chicago, Illinois; Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Cristina Bardita
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Jiwang Chen
- Division of Pulmonary, Critical Care, Sleep and Allergy, University of Illinois at Chicago, Chicago, Illinois
| | - Niranjan Jeganathan
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Melanie Pritchard
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia
| | - Salvatore DiBartolo
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Roberto Machado
- Division of Pulmonary, Critical Care, Sleep and Allergy, University of Illinois at Chicago, Chicago, Illinois
| | - Sanda Predescu
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois.
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Herrero-Garcia E, O'Bryan JP. Intersectin scaffold proteins and their role in cell signaling and endocytosis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:23-30. [PMID: 27746143 DOI: 10.1016/j.bbamcr.2016.10.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 10/08/2016] [Indexed: 11/29/2022]
Abstract
Intersectins (ITSNs) are a family of multi-domain proteins involved in regulation of diverse cellular pathways. These scaffold proteins are well known for regulating endocytosis but also play important roles in cell signaling pathways including kinase regulation and Ras activation. ITSNs participate in several human cancers, such as neuroblastomas and glioblastomas, while their downregulation is associated with lung injury. Alterations in ITSN expression have been found in neurodegenerative diseases such as Down Syndrome and Alzheimer's disease. Binding proteins for ITSNs include endocytic regulatory factors, cytoskeleton related proteins (i.e. actin or dynamin), signaling proteins as well as herpes virus proteins. This review will summarize recent studies on ITSNs, highlighting the importance of these scaffold proteins in the aforementioned processes.
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Affiliation(s)
- Erika Herrero-Garcia
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL 60612, USA; Jesse Brown VA Medical Center, Chicago, IL 60612, USA
| | - John P O'Bryan
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL 60612, USA; Jesse Brown VA Medical Center, Chicago, IL 60612, USA.
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Jeganathan N, Predescu D, Zhang J, Sha F, Bardita C, Patel M, Wood S, Borgia JA, Balk RA, Predescu S. Rac1-mediated cytoskeleton rearrangements induced by intersectin-1s deficiency promotes lung cancer cell proliferation, migration and metastasis. Mol Cancer 2016; 15:59. [PMID: 27629044 PMCID: PMC5024437 DOI: 10.1186/s12943-016-0543-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 09/06/2016] [Indexed: 12/21/2022] Open
Abstract
Background The mechanisms involved in lung cancer (LC) progression are poorly understood making discovery of successful therapies difficult. Adaptor proteins play a crucial role in cancer as they link cell surface receptors to specific intracellular pathways. Intersectin-1s (ITSN-1s) is an important multidomain adaptor protein implicated in the pathophysiology of numerous pulmonary diseases. To date, the role of ITSN-1s in LC has not been studied. Methods Human LC cells, human LC tissue and A549 LC cells stable transfected with myc-ITSN-1s construct (A549 + ITSN-1s) were used in correlation with biochemical, molecular biology and morphological studies. In addition scratch assay with time lapse microscopy and in vivo xenograft tumor and mouse metastasis assays were performed. Results ITSN-1s, a prevalent protein of lung tissue, is significantly downregulated in human LC cells and LC tissue. Restoring ITSN-1s protein level decreases LC cell proliferation and clonogenic potential. In vivo studies indicate that immunodeficient mice injected with A549 + ITSN-1s cells develop less and smaller metastatic tumors compared to mice injected with A549 cells. Our studies also show that restoring ITSN-1s protein level increases the interaction between Cbl E3 ubiquitin ligase and Eps8 resulting in enhanced ubiquitination of the Eps8 oncoprotein. Subsequently, downstream unproductive assembly of the Eps8-mSos1 complex leads to impaired activation of the small GTPase Rac1. Impaired Rac1 activation mediated by ITSN-1s reorganizes the cytoskeleton (increased thick actin bundles and focal adhesion (FA) complexes as well as collapse of the vimentin filament network) in favor of decreased LC cell migration and metastasis. Conclusion ITSN-1s induced Eps8 ubiquitination and impaired Eps8-mSos1 complex formation, leading to impaired activation of Rac1, is a novel signaling mechanism crucial for abolishing the progression and metastatic potential of LC cells. Electronic supplementary material The online version of this article (doi:10.1186/s12943-016-0543-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Niranjan Jeganathan
- Division of Pulmonary and Critical Care Medicine, Rush University Medical Center and Rush Medical College, 1750 W. Harrison Street, 299 Jelke South Center, Chicago, IL, 60612, USA.
| | - Dan Predescu
- Department of Pharmacology and Division of Pulmonary and Critical Care Medicine, Rush University, 1750 W. Harrison Street, 1415 Jelke, Chicago, IL, 60612, USA
| | - Jin Zhang
- Department of Pharmacology, Rush University, 1750 W. Harrison Street, 1533 Jelke, Chicago, IL, 60612, USA
| | - Fei Sha
- Department of Pharmacology, Rush University, 1750 W. Harrison Street, 1533 Jelke, Chicago, IL, 60612, USA
| | - Cristina Bardita
- Department of Pharmacology, Rush University, 1750 W. Harrison Street, 1537 Jelke, Chicago, IL, 60612, USA
| | - Monal Patel
- Department of Pharmacology, Rush University, 1750 W. Harrison Street, 1533 Jelke, Chicago, IL, 60612, USA
| | - Stephen Wood
- Department of Immunology, Rush University, 1735 W. Harrison Street, 663 Cohn, Chicago, IL, 60612, USA
| | - Jeffrey A Borgia
- Department of Biochemistry, Rush University, 1750 W. Harrison Street, 1415 Jelke, Chicago, IL, 60612, USA
| | - Robert A Balk
- Division of Pulmonary and Critical Care Medicine, Rush University Medical Center and Rush Medical College, 1750 W. Harrison Street, 293 Jelke, Chicago, IL, 60612, USA
| | - Sanda Predescu
- Department of Pharmacology and Division of Pulmonary and Critical Care Medicine, Rush University Medical Center and Rush Medical College, 1750 W. Harrison Street, 1535 Jelke, Chicago, IL, 60612, USA
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Yang X, Yan F, He Z, Liu S, Cheng Y, Wei K, Gan S, Yuan J, Wang S, Xiao Y, Ren K, Liu N, Hu X, Ding X, Hu X, Xiang S. ITSN2L Interacts with and Negatively Regulates RABEP1. Int J Mol Sci 2015; 16:28242-54. [PMID: 26633357 PMCID: PMC4691038 DOI: 10.3390/ijms161226091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Revised: 10/28/2015] [Accepted: 11/02/2015] [Indexed: 01/26/2023] Open
Abstract
Intersectin-2Long (ITSN2L) is a multi-domain protein participating in endocytosis and exocytosis. In this study, RABEP1 was identified as a novel ITSN2L interacting protein using a yeast two-hybrid screen from a human brain cDNA library and this interaction, specifically involving the ITSN2L CC domain and RABEP1 CC3 regions, was further confirmed by in vitro GST (glutathione-S-transferase) pull-down and in vivo co-immunoprecipitation assays. Corroboratively, we observed that these two proteins co-localize in the cytoplasm of mammalian cells. Furthermore, over-expression of ITSN2L promotes RABEP1 degradation and represses RABEP1-enhanced endosome aggregation, indicating that ITSN2L acts as a negative regulator of RABEP1. Finally, we showed that ITSN2L and RABEP1 play opposite roles in regulating endocytosis. Taken together, our results indicate that ITSN2L interacts with RABEP1 and stimulates its degradation in regulation of endocytosis.
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Affiliation(s)
- Xiaoxu Yang
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Feng Yan
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Zhicheng He
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Shan Liu
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Yeqing Cheng
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Ke Wei
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Shiquan Gan
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Jing Yuan
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Shang Wang
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Ye Xiao
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Kaiqun Ren
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Ning Liu
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Xiang Hu
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Xiaofeng Ding
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Xingwang Hu
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha 410081, China.
| | - Shuanglin Xiang
- Key Laboratory of Protein Chemistry and Developmental Biology of State Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
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Shi H, Wu W, Luo J. Investigation of the effect of nocodazole on the PI3K/Akt signaling pathway in COS7 cells. Mol Med Rep 2014; 10:3233-40. [PMID: 25323455 DOI: 10.3892/mmr.2014.2632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Accepted: 09/09/2014] [Indexed: 11/06/2022] Open
Abstract
A number of studies have demonstrated that nocodazole suppresses Akt phosphorylation; however, the underlying molecular mechanism remains unclear. In the current study, the mechanism of nocodazole‑induced suppression of Akt phosphorylation was investigated. The cell cycle was analyzed using flow cytometry and EGF receptor dimerization was evaluated through a cross-linking assay. Immunoprecipitation experiments were performed to investigate the interaction between P85 and EGFR and cell migration was evaluated through a wound healing assay. COS7 cells were observed to be rounded following a 24‑h treatment with nocodazole, and the results revealed that ~45% of COS7 cells were arrested at the G2/M phase and that the cyclin B1 expression level was greatly increased. EGF‑mediated Akt phosphorylation was markedly inhibited in nocodazole‑treated cells. In addition, the levels of internalized EGF‑EGFR complexes in nocodazole‑treated cells were reduced, and EGF‑EGFR dimerization was found to be affected by nocodazole. Akt phosphorylation in COS7 cells was demonstrated to be overridden by AG1478 and wortmannin. The results also showed that p85 did not bind to activated EGFR in nocodazole‑treated cells, and that nocodazole and protein inhibitors reduced cell migration. In summary, these results indicate that nocodazole inhibits the PI3K/Akt pathway by interfering with the binding of p85 binding to activated EGFR and further affects the growth of cells.
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Affiliation(s)
- Huaiping Shi
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, P.R. China
| | - Wujun Wu
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an City, Shaanxi 710068, P.R. China
| | - Jun Luo
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, P.R. China
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12
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Bardita C, Predescu D, Justice MJ, Petrache I, Predescu S. In vivo knockdown of intersectin-1s alters endothelial cell phenotype and causes microvascular remodeling in the mouse lungs. Apoptosis 2013; 18:57-76. [PMID: 23054079 PMCID: PMC3543613 DOI: 10.1007/s10495-012-0762-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Intersectin-1s (ITSN-1s) is a general endocytic protein involved in regulating lung vascular permeability and endothelial cells (ECs) survival, via MEK/Erk1/2MAPK signaling. To investigate the in vivo effects of ITSN-1s deficiency and the resulting ECs apoptosis on pulmonary vasculature and lung homeostasis, we used an ITSN-1s knocked-down (KDITSN) mouse generated by repeated delivery of a specific siRNA targeting ITSN-1 gene (siRNAITSN). Biochemical and histological analyses as well as electron microscopy (EM) revealed that acute KDITSN [3-days (3d) post-siRNAITSN treatment] inhibited Erk1/2MAPK pro-survival signaling, causing significant ECs apoptosis and lung injury; at 10d of KDITSN, caspase-3 activation was at peak, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive ECs showed 3.4-fold increase, the mean linear intercept (MLI) showed 48 % augment and pulmonary microvessel density as revealed by aquaporin-1 staining (AQP-1) decreased by 30 %, all compared to controls; pulmonary function was altered. Concomitantly, expression of several growth factors known to activate Erk1/2MAPK and suppress Bad pro-apoptotic activity increased. KDITSN altered Smads activity, downstream of the transforming growth factor beta-receptor-1 (TβR1), as shown by subcellular fractionation and immunoblot analyses. Moreover, 24d post-siRNAITSN, surviving ECs became hyper-proliferative and apoptotic-resistant against ITSN-1s deficiency, as demonstrated by EM imaging, 5-bromo-deoxyuridine (BrdU) incorporation and Bad-Ser112/155 phosphorylation, respectively, leading to increased microvessel density and repair of the injured lungs, as well as matrix deposition. In sum, ECs endocytic dysfunction and apoptotic death caused by KDITSN contribute to the initial lung injury and microvascular loss, followed by endothelial phenotypic changes and microvascular remodeling in the remaining murine pulmonary microvascular bed.
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Affiliation(s)
- Cristina Bardita
- Department of Pharmacology, Rush University, 1735 W. Harrison St., Chicago, IL 60612, USA
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13
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Predescu DN, Bardita C, Tandon R, Predescu SA. Intersectin-1s: an important regulator of cellular and molecular pathways in lung injury. Pulm Circ 2013; 3:478-98. [PMID: 24618535 PMCID: PMC4070809 DOI: 10.1086/674439] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Abstract Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe syndromes resulting from the diffuse damage of the pulmonary parenchyma. ALI and ARDS are induced by a plethora of local or systemic insults, leading to the activation of multiple pathways responsible for injury, resolution, and repair or scarring of the lungs. Despite the large efforts aimed at exploring the roles of different pathways in humans and animal models and the great strides made in understanding the pathogenesis of ALI/ARDS, the only viable treatment options are still dependent on ventilator and cardiovascular support. Investigation of the pathophysiological mechanisms responsible for initiation and resolution or advancement toward lung scarring in ALI/ARDS animal models led to a better understanding of the disease's complexity and helped in elucidating the links between ALI and systemic multiorgan failure. Although animal models of ALI/ARDS have pointed out a variety of new ideas for study, there are still limited data regarding the initiating factors, the critical steps in the progression of the disease, and the central mechanisms dictating its resolution or progression to lung scarring. Recent studies link deficiency of intersectin-1s (ITSN-1s), a prosurvival protein of lung endothelial cells, to endothelial barrier dysfunction and pulmonary edema as well as to the repair/recovery from ALI. This review discusses the effects of ITSN-1s deficiency on pulmonary endothelium and its significance in the pathology of ALI/ARDS.
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Affiliation(s)
- Dan N Predescu
- 1 Department of Pharmacology, Rush University, Chicago, Illinois, USA
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14
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Patel M, Predescu D, Tandon R, Bardita C, Pogoriler J, Bhorade S, Wang M, Comhair S, Ryan-Hemnes A, Chen J, Machado R, Husain A, Erzurum S, Predescu S. A novel p38 mitogen-activated protein kinase/Elk-1 transcription factor-dependent molecular mechanism underlying abnormal endothelial cell proliferation in plexogenic pulmonary arterial hypertension. J Biol Chem 2013; 288:25701-25716. [PMID: 23893408 DOI: 10.1074/jbc.m113.502674] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plexiform lesions (PLs), the hallmark of plexogenic pulmonary arterial hypertension (PAH), contain phenotypically altered, proliferative endothelial cells (ECs). The molecular mechanism that contributes to EC proliferation and formation of PLs is poorly understood. We now show that a decrease in intersectin-1s (ITSN-1s) expression due to granzyme B (GrB) cleavage during inflammation associated with PAH and the high p38/Erk1/2(MAPK) activity ratio caused by the GrB/ITSN cleavage products lead to EC proliferation and selection of a proliferative/plexiform EC phenotype. We used human pulmonary artery ECs of PAH subjects (EC(PAH)), paraffin-embedded and frozen human lung tissue, and animal models of PAH in conjunction with microscopy imaging, biochemical, and molecular biology approaches to demonstrate that GrB cleaves ITSN-1s, a prosurvival protein of lung ECs, and generates two biologically active fragments, an N-terminal fragment (GrB-EH(ITSN)) with EC proliferative potential and a C-terminal product with dominant negative effects on Ras/Erk1/2. The proliferative potential of GrB-EH(ITSN) is mediated via sustained phosphorylation of p38(MAPK) and Elk-1 transcription factor and abolished by chemical inhibition of p38(MAPK). Moreover, lung tissue of PAH animal models and human specimens and EC(PAH) express lower levels of ITSN-1s compared with controls and the GrB-EH(ITSN) cleavage product. Moreover, GrB immunoreactivity is associated with PLs in PAH lungs. The concurrent expression of the two cleavage products results in a high p38/Erk1/2(MAPK) activity ratio, which is critical for EC proliferation. Our findings identify a novel GrB-EH(ITSN)-dependent pathogenic p38(MAPK)/Elk-1 signaling pathway involved in the poorly understood process of PL formation in severe PAH.
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Affiliation(s)
- Monal Patel
- From the Departments of Pharmacology and Medicine, Vascular Biology, and Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago, Illinois 60612
| | - Dan Predescu
- From the Departments of Pharmacology and Medicine, Vascular Biology, and Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago, Illinois 60612
| | - Rajive Tandon
- From the Departments of Pharmacology and Medicine, Vascular Biology, and Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago, Illinois 60612
| | - Cristina Bardita
- From the Departments of Pharmacology and Medicine, Vascular Biology, and Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago, Illinois 60612
| | | | - Sangeeta Bhorade
- Center for Lung Transplant, University of Chicago, Chicago, Illinois 60637
| | - Minhua Wang
- From the Departments of Pharmacology and Medicine, Vascular Biology, and Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago, Illinois 60612
| | - Suzy Comhair
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Anna Ryan-Hemnes
- Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University, Nashville, Tennessee 37240, and
| | - Jiwang Chen
- Section of Pulmonary, Critical Care Medicine, Sleep and Allergy, University of Illinois, Chicago, Illinois 60612
| | - Roberto Machado
- Section of Pulmonary, Critical Care Medicine, Sleep and Allergy, University of Illinois, Chicago, Illinois 60612
| | | | - Serpil Erzurum
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Sanda Predescu
- From the Departments of Pharmacology and Medicine, Vascular Biology, and Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago, Illinois 60612,.
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15
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Emerging roles for intersectin (ITSN) in regulating signaling and disease pathways. Int J Mol Sci 2013; 14:7829-52. [PMID: 23574942 PMCID: PMC3645719 DOI: 10.3390/ijms14047829] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 01/10/2023] Open
Abstract
Intersectins (ITSNs) represent a family of multi-domain adaptor proteins that regulate endocytosis and cell signaling. ITSN genes are highly conserved and present in all metazoan genomes examined thus far. Lower eukaryotes have only one ITSN gene, whereas higher eukaryotes have two ITSN genes. ITSN was first identified as an endocytic scaffold protein, and numerous studies reveal a conserved role for ITSN in endocytosis. Subsequently, ITSNs were found to regulate multiple signaling pathways including receptor tyrosine kinases (RTKs), GTPases, and phosphatidylinositol 3-kinase Class 2beta (PI3KC2β). ITSN has also been implicated in diseases such as Down Syndrome (DS), Alzheimer Disease (AD), and other neurodegenerative disorders. This review summarizes the evolutionary conservation of ITSN, the latest research on the role of ITSN in endocytosis, the emerging roles of ITSN in regulating cell signaling pathways, and the involvement of ITSN in human diseases such as DS, AD, and cancer.
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16
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Zhang W, Shen Y, Xiong G, Guo Y, Deng L, Li B, Yang J, Qi C. Crystal structure of human Intersectin-2L C2 domain. Biochem Biophys Res Commun 2012; 431:76-80. [PMID: 23274495 DOI: 10.1016/j.bbrc.2012.12.087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 12/19/2012] [Indexed: 01/17/2023]
Abstract
Intersectin-2L (ITSN-2L) is a long isoform of ITSN family, which is a multimodule scaffolding protein functioning in membrane-associated molecular trafficking and signal transduction pathways. ITSN-2L possesses a carboxy-terminal extension encoding a Dbl homology domain (DH), a pleckstrin homology domain (PH) and a C2 domain, suggesting that it could act as a guanine nucleotide exchange factor for Rho-like GTPases. But the role of C2 domain is obscure in this process. Here we report the crystal structure of human ITSN-2L C2 domain at 1.56Å resolution. The sequence and structural alignment of ITSN-2L C2 domain with other members of C2 domain protein family indicate its vital cellular roles in membrane trafficking, the generation of lipid-second messengers and activation of GTPases. Moreover, our data show the possible roles of ITSN-2L C2 domain in regulating the activity of Cdc42.
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Affiliation(s)
- Wei Zhang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079, PR China
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17
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Wong KA, Wilson J, Russo A, Wang L, Okur MN, Wang X, Martin NP, Scappini E, Carnegie GK, O'Bryan JP. Intersectin (ITSN) family of scaffolds function as molecular hubs in protein interaction networks. PLoS One 2012; 7:e36023. [PMID: 22558309 PMCID: PMC3338775 DOI: 10.1371/journal.pone.0036023] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 03/28/2012] [Indexed: 11/29/2022] Open
Abstract
Members of the intersectin (ITSN) family of scaffold proteins consist of multiple modular domains, each with distinct ligand preferences. Although ITSNs were initially implicated in the regulation of endocytosis, subsequent studies have revealed a more complex role for these scaffold proteins in regulation of additional biochemical pathways. In this study, we performed a high throughput yeast two-hybrid screen to identify additional pathways regulated by these scaffolds. Although several known ITSN binding partners were identified, we isolated more than 100 new targets for the two mammalian ITSN proteins, ITSN1 and ITSN2. We present the characterization of several of these new targets which implicate ITSNs in the regulation of the Rab and Arf GTPase pathways as well as regulation of the disrupted in schizophrenia 1 (DISC1) interactome. In addition, we demonstrate that ITSN proteins form homomeric and heteromeric complexes with each other revealing an added level of complexity in the function of these evolutionarily conserved scaffolds.
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Affiliation(s)
- Katy A. Wong
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Center for Cardiovascular Research, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- UIC Cancer Center, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Jessica Wilson
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Center for Cardiovascular Research, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- UIC Cancer Center, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Angela Russo
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Center for Cardiovascular Research, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- UIC Cancer Center, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Li Wang
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Mustafa Nazir Okur
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Center for Cardiovascular Research, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- UIC Cancer Center, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Department of Biochemistry and Molecular Genetics, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Xuerong Wang
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Center for Cardiovascular Research, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- UIC Cancer Center, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Negin P. Martin
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, United States of America
| | - Erica Scappini
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, United States of America
| | - Graeme K. Carnegie
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - John P. O'Bryan
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- Center for Cardiovascular Research, University of Illinois College of Medicine, Chicago, Illinois, United States of America
- UIC Cancer Center, University of Illinois College of Medicine, Chicago, Illinois, United States of America
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18
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Impaired caveolae function and upregulation of alternative endocytic pathways induced by experimental modulation of intersectin-1s expression in mouse lung endothelium. Biochem Res Int 2012; 2012:672705. [PMID: 22506115 PMCID: PMC3299393 DOI: 10.1155/2012/672705] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 11/16/2011] [Indexed: 11/17/2022] Open
Abstract
Intersectin-1s (ITSN-1s), a protein containing five SH3 (A-E) domains, regulates via the SH3A the function of dynamin-2 (dyn2) at the endocytic site. ITSN-1s expression was modulated in mouse lung endothelium by liposome delivery of either a plasmid cDNA encoding myc-SH3A or a specific siRNA targeting ITSN-1 gene. The lung vasculature of SH3A-transduced and ITSN-1s- deficient mice was perfused with gold albumin (Au-BSA) to analyze by electron microscopy the morphological intermediates and pathways involved in transendothelial transport or with dinitrophenylated (DNP)-BSA to quantify by ELISA its transport. Acute modulation of ITSN-1s expression decreased the number of caveolae, impaired their transport, and opened the interendothelial junctions, while upregulating compensatory nonconventional endocytic/transcytotic structures. Chronic inhibition of ITSN-1s further increased the occurrence of nonconventional intermediates and partially restored the junctional integrity. These findings indicate that ITSN-1s expression is required for caveolae function and efficient transendothelial transport. Moreover, our results demonstrate that ECs are highly adapted to perform their transport function while maintaining lung homeostasis.
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19
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Intersectin 1 enhances Cbl ubiquitylation of epidermal growth factor receptor through regulation of Sprouty2-Cbl interaction. Mol Cell Biol 2011; 32:817-25. [PMID: 22158968 DOI: 10.1128/mcb.05647-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ubiquitylation of receptor tyrosine kinases plays a critical role in regulating the trafficking and lysosomal degradation of these important signaling molecules. We identified the multidomain scaffolding protein intersectin 1 (ITSN1) as an important regulator of this process (N. P. Martin et al., Mol. Pharmacol. 70:1463-1653, 2006) ITSN1 stimulates ubiquitylation of the epidermal growth factor receptor (EGFR) through enhancing the activity of the Cbl E3 ubiquitin ligase. However, the precise mechanism through which ITSN1 enhances Cbl activity was unclear. In this study, we found that ITSN1 enhances Cbl activity through disrupting the interaction of Cbl with the Sprouty2 (Spry2) inhibitory protein. We demonstrate that ITSN1 binds Pro-rich regions in both Cbl and Spry2 and that interaction of ITSN1 with Spry2 disrupts Spry2-Cbl interaction, resulting in enhanced ubiquitylation of the EGFR. Disruption of ITSN1 binding to Spry2 through point mutation of the Pro-rich ITSN1 binding site in Spry2 results in enhanced Cbl-Spry2 interaction and inhibition of receptor ubiquitylation. This study demonstrates that ITSN1 enhances Cbl activity by modulating the interaction of Cbl with Spry2. In addition, our results reveal a new level of complexity in the regulation of Cbl through the interaction with ITSN1 and Spry2.
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20
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Abstract
Defining the subcellular distribution of signaling complexes is imperative to understanding the output from that complex. Conventional methods such as immunoprecipitation do not provide information on the spatial localization of complexes. In contrast, BiFC monitors the interaction and subcellular compartmentalization of protein complexes. In this method, a fluororescent protein is split into amino- and carboxy-terminal non-fluorescent fragments which are then fused to two proteins of interest. Interaction of the proteins results in reconstitution of the fluorophore (Figure 1). A limitation of BiFC is that once the fragmented fluorophore is reconstituted the complex is irreversible. This limitation is advantageous in detecting transient or weak interactions, but precludes a kinetic analysis of complex dynamics. An additional caveat is that the reconstituted flourophore requires 30min to mature and fluoresce, again precluding the observation of real time interactions. BiFC is a specific example of the protein fragment complementation assay (PCA) which employs reporter proteins such as green fluorescent protein variants (BiFC), dihydrofolate reductase, b-lactamase, and luciferase to measure protein:protein interactions. Alternative methods to study protein:protein interactions in cells include fluorescence co-localization and Förster resonance energy transfer (FRET). For co-localization, two proteins are individually tagged either directly with a fluorophore or by indirect immunofluorescence. However, this approach leads to high background of non-interacting proteins making it difficult to interpret co-localization data. In addition, due to the limits of resolution of confocal microscopy, two proteins may appear co-localized without necessarily interacting. With BiFC, fluorescence is only observed when the two proteins of interest interact. FRET is another excellent method for studying protein:protein interactions, but can be technically challenging. FRET experiments require the donor and acceptor to be of similar brightness and stoichiometry in the cell. In addition, one must account for bleed through of the donor into the acceptor channel and vice versa. Unlike FRET, BiFC has little background fluorescence, little post processing of image data, does not require high overexpression, and can detect weak or transient interactions. Bioluminescence resonance energy transfer (BRET) is a method similar to FRET except the donor is an enzyme (e.g. luciferase) that catalyzes a substrate to become bioluminescent thereby exciting an acceptor. BRET lacks the technical problems of bleed through and high background fluorescence but lacks the ability to provide spatial information due to the lack of substrate localization to specific compartments. Overall, BiFC is an excellent method for visualizing subcellular localization of protein complexes to gain insight into compartmentalized signaling.
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Affiliation(s)
- Katy A Wong
- Department of Pharmacology, University of Illinois at Chicago, USA
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21
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Intersectin multidomain adaptor proteins: Regulation of functional diversity. Gene 2011; 473:67-75. [DOI: 10.1016/j.gene.2010.11.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 11/30/2010] [Accepted: 11/30/2010] [Indexed: 12/17/2022]
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22
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Primeau M, Ouadda ABD, Lamarche-Vane N. Cdc42 GTPase-activating protein (CdGAP) interacts with the SH3D domain of Intersectin through a novel basic-rich motif. FEBS Lett 2011; 585:847-53. [DOI: 10.1016/j.febslet.2011.02.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 01/24/2011] [Accepted: 02/10/2011] [Indexed: 12/26/2022]
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23
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Oeste CL, Díez-Dacal B, Bray F, García de Lacoba M, de la Torre BG, Andreu D, Ruiz-Sánchez AJ, Pérez-Inestrosa E, García-Domínguez CA, Rojas JM, Pérez-Sala D. The C-terminus of H-Ras as a target for the covalent binding of reactive compounds modulating Ras-dependent pathways. PLoS One 2011; 6:e15866. [PMID: 21253588 PMCID: PMC3017061 DOI: 10.1371/journal.pone.0015866] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 11/25/2010] [Indexed: 12/30/2022] Open
Abstract
Ras proteins are crucial players in differentiation and oncogenesis and constitute important drug targets. The localization and activity of Ras proteins are highly dependent on posttranslational modifications at their C-termini. In addition to an isoprenylated cysteine, H-Ras, but not other Ras proteins, possesses two cysteine residues (C181 and C184) in the C-terminal hypervariable domain that act as palmitoylation sites in cells. Cyclopentenone prostaglandins (cyPG) are reactive lipidic mediators that covalently bind to H-Ras and activate H-Ras dependent pathways. Dienone cyPG, such as 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) and Δ12-PGJ2 selectively bind to the H-Ras hypervariable domain. Here we show that these cyPG bind simultaneously C181 and C184 of H-Ras, thus potentially altering the conformational tendencies of the hypervariable domain. Based on these results, we have explored the capacity of several bifunctional cysteine reactive small molecules to bind to the hypervariable domain of H-Ras proteins. Interestingly, phenylarsine oxide (PAO), a widely used tyrosine phosphatase inhibitor, and dibromobimane, a cross-linking agent used for cysteine mapping, effectively bind H-Ras hypervariable domain. The interaction of PAO with H-Ras takes place in vitro and in cells and blocks modification of H-Ras by 15d-PGJ2. Moreover, PAO treatment selectively alters H-Ras membrane partition and the pattern of H-Ras activation in cells, from the plasma membrane to endomembranes. These results identify H-Ras as a novel target for PAO. More importantly, these observations reveal that small molecules or reactive intermediates interacting with spatially vicinal cysteines induce intramolecular cross-linking of H-Ras C-terminus potentially contributing to the modulation of Ras-dependent pathways.
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Affiliation(s)
- Clara L. Oeste
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Beatriz Díez-Dacal
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Francesca Bray
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Mario García de Lacoba
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Beatriz G. de la Torre
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - David Andreu
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | | | | | - Carlota A. García-Domínguez
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
| | - José M. Rojas
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
| | - Dolores Pérez-Sala
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- * E-mail:
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24
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Abstract
The endocytic pathway is involved in activation and inhibition of cellular signaling. Thus, defining the regulatory mechanisms that link endocytosis and cellular signaling is of interest. An emerging link between these processes is a family of proteins called intersectins (ITSNs). These multidomain proteins serve as scaffolds in the assembly of endocytic vesicles and also regulate components of various signaling pathways, including kinases, guanosine triphosphatases, and ubiquitin ligases. This review summarizes research on the role of ITSNs in regulating both endocytic and signal transduction pathways, discusses the link between ITSNs and human disease, and highlights future directions in the study of ITSNs.
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Affiliation(s)
- John P O'Bryan
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL 60612, USA.
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25
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Dergai M, Tsyba L, Dergai O, Zlatskii I, Skrypkina I, Kovalenko V, Rynditch A. Microexon-based regulation of ITSN1 and Src SH3 domains specificity relies on introduction of charged amino acids into the interaction interface. Biochem Biophys Res Commun 2010; 399:307-12. [PMID: 20659428 DOI: 10.1016/j.bbrc.2010.07.080] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 07/22/2010] [Indexed: 11/25/2022]
Abstract
SH3 domains function as protein-protein interaction modules in assembly of signalling and endocytic protein complexes. Here we report investigations of the mechanism of regulation of the binding properties of the SH3 domains of intersectin (ITSN1) and Src kinase by alternative splicing. Comparative sequence analysis of ITSN1 and Src genes revealed the conservation of alternatively spliced microexons affecting the structure of the SH3 domains in vertebrates. We show that neuron-specific ITSN1 transcripts containing the microexon 20 that encodes five amino acid residues within the SH3A domain are expressed in zebrafish from the earliest stages of the development of the nervous system. Models of alternative isoforms of the ITSN1 SH3A domain revealed that the insertion encoded by the microexon is located at the beginning of the n-Src loop of this domain causing a shift of negatively charged amino acids towards the interaction interface. Mutational analysis confirmed the importance of translocation of these negatively charged amino acids for interaction with dynamin 1. We also identified a residue within the microexon-encoded insert in the SH3 domain of brain-specific variant of Src that abolishes interaction of the domain with dynamin 1. Thus microexons provide a mechanism for the control of tissue-specific interactions of ITSN1 and Src with their partners.
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Affiliation(s)
- Mykola Dergai
- Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03680, Ukraine.
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Pyrzynska B, Pilecka I, Miaczynska M. Endocytic proteins in the regulation of nuclear signaling, transcription and tumorigenesis. Mol Oncol 2009; 3:321-38. [PMID: 19577966 DOI: 10.1016/j.molonc.2009.06.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 06/01/2009] [Accepted: 06/02/2009] [Indexed: 01/14/2023] Open
Abstract
Accumulating evidence argues that many proteins governing membrane sorting during endocytosis participate also in nuclear signaling and transcriptional regulation, mostly by modulating the activity of various nuclear factors. Some adaptors and accessory proteins acting in clathrin-mediated internalization, as well as endosomal sorting proteins can undergo nuclear translocation and affect gene expression directly, while for others the effects may be more indirect. Although it is often unclear to what extent the endocytic and nuclear functions are interrelated, several of such proteins are implicated in the regulation of cell proliferation and tumorigenesis, arguing that their dual-function nature may be of physiological importance.
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Affiliation(s)
- Beata Pyrzynska
- International Institute of Molecular and Cell Biology, Laboratory of Cell Biology, 02-109 Warsaw, Poland
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Abstract
In the past 20 years, the discovery and characterization of the molecular machinery that controls cellular polarization have enabled us to achieve a better understanding of many biological processes. Spatial asymmetry or establishment of cell polarity during embryogenesis, epithelial morphogenesis, neuronal differentiation, and migration of fibroblasts and T cells are thought to rely on a small number of evolutionarily conserved proteins and pathways. Correct polarization is crucial for normal cell physiology and tissue homeostasis, and is lost in cancer. Thus, cell polarity signaling is likely to have an important function in tumor progression. Recent findings have identified a regulator of cell polarity, the Par complex, as an important signaling node in tumorigenesis. In normal cell types, the Par complex is part of the molecular machinery that regulates cell polarity and maintains normal cell homeostasis. As such, the polarity regulators are proposed to have a tumor suppressor function, consistent with the loss of polarity genes associated with hyperproliferation in Drosophila melanogaster. However, recent studies showing that some members of this complex also display pro-oncogenic activities suggest a more complex regulation of the polarity machinery during cellular transformation. Here, we examine the existing data about the different functions of the Par complex. We discuss how spatial restriction, binding partners and substrate specificity determine the signaling properties of Par complex proteins. A better understanding of these processes will very likely shed some light on how the Par complex can switch from a normal polarity regulation function to promotion of transformation downstream of oncogenes.
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Ma N, Niu RF, Ma YJ. Intersectin 1: a molecular linker in the central nervous system. Neurosci Bull 2008; 24:401-5. [PMID: 19037327 DOI: 10.1007/s12264-008-0715-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Down syndrome (DS) is the most common cause of cognitive impairment associated with a congenital chromosomal abnormality, trisomy of chromosome 21. Mental retardation and congenital heart defects are key features of DS. All DS individuals develop early-onset Alzheimer's disease-like neuropathology. Intersectin 1 gene is localized on human chromosome 21, the critical region of DS, and it has higher expression in the brain of DS patients than in normal individuals. So fully understanding functions of intersectin 1 is critical for revealing the pathogenesis of DS. Intersectin 1 protein has two isoforms: intersectin 1-L and intersectin 1-S. This review will focus on the distribution, expression characters and functions of intersectin 1 in the central nervous system.
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Affiliation(s)
- Ning Ma
- Center Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital of Ministry of Education, Tianjin, China
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Xie J, Vandenbroere I, Pirson I. SHIP2 associates with intersectin and recruits it to the plasma membrane in response to EGF. FEBS Lett 2008; 582:3011-7. [DOI: 10.1016/j.febslet.2008.07.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 07/03/2008] [Accepted: 07/03/2008] [Indexed: 11/17/2022]
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30
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Yu Y, Chu PY, Bowser DN, Keating DJ, Dubach D, Harper I, Tkalcevic J, Finkelstein DI, Pritchard MA. Mice deficient for the chromosome 21 ortholog Itsn1 exhibit vesicle-trafficking abnormalities. Hum Mol Genet 2008; 17:3281-90. [PMID: 18676989 DOI: 10.1093/hmg/ddn224] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Enlarged early endosomes in the neurons of young Down syndrome (DS) and pre-Alzheimer's disease (AD) brains suggest that a disturbance in endocytosis is one of the earliest hallmarks of AD pathogenesis in both conditions. We identified a chromosome 21 gene, Intersectin-1 (ITSN1) that is up-regulated in DS brains and has a putative function in endocytosis and vesicle trafficking. To elucidate the function of ITSN1 and assess its contribution to endocytic defects associated with DS and AD, we generated Itsn1 null mice. In knockout mice we found alterations in a number of parameters associated with endocytic and vesicle trafficking events. We found a reduced number of exocytosis events in chromaffin cells and a slowing of endocytosis in neurons. Endosome size was increased in neurons and NGF levels were reduced in the septal region of the brain. Our data is the first indication that Itsn1 has a role in endocytosis in an in vivo mammalian model, and that a disruption in Itsn1 expression causes a disturbance in vesicle trafficking and endocytic function in the brain. These results imply a role for ITSN1 in the early endocytic anomalies reported in DS brains which may have ramifications for the onset of AD.
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Affiliation(s)
- Yong Yu
- Departments of Biochemistry and Molecular Biology and Anatomy and Developmental Biology, Monash University, Building 13C, Wellington Rd, Clayton 3168, Victoria, Australia
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Chabu C, Doe CQ. Dap160/intersectin binds and activates aPKC to regulate cell polarity and cell cycle progression. Development 2008; 135:2739-46. [PMID: 18614576 DOI: 10.1242/dev.024059] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The atypical protein kinase C (aPKC) is required for cell polarization of many cell types, and is upregulated in several human tumors. Despite its importance in cell polarity and growth control, relatively little is known about how aPKC activity is regulated. Here, we use a biochemical approach to identify Dynamin-associated protein 160 (Dap160; related to mammalian intersectin) as an aPKC-interacting protein in Drosophila. We show that Dap160 directly interacts with aPKC, stimulates aPKC activity in vitro and colocalizes with aPKC at the apical cortex of embryonic neuroblasts. In dap160 mutants, aPKC is delocalized from the neuroblast apical cortex and has reduced activity, based on its inability to displace known target proteins from the basal cortex. Both dap160 and aPKC mutants have fewer proliferating neuroblasts and a prolonged neuroblast cell cycle. We conclude that Dap160 positively regulates aPKC activity and localization to promote neuroblast cell polarity and cell cycle progression.
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Affiliation(s)
- Chiswili Chabu
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
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Won JS, Im YB, Khan M, Contreras M, Singh AK, Singh I. Lovastatin inhibits amyloid precursor protein (APP) beta-cleavage through reduction of APP distribution in Lubrol WX extractable low density lipid rafts. J Neurochem 2008; 105:1536-49. [PMID: 18266936 DOI: 10.1111/j.1471-4159.2008.05283.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previous studies have described that statins (inhibitors of cholesterol and isoprenoid biosynthesis) inhibit the output of amyloid-beta (Abeta) in the animal model and thus decrease risk of Alzheimer's disease. However, their action mechanism(s) in Abeta precursor protein (APP) processing and Abeta generation is not fully understood. In this study, we report that lovastatin treatment reduced Abeta output in cultured hippocampal neurons as a result of reduced APP levels and beta-secretase activities in low density Lubrol WX (non-ionic detergent) extractable lipid rafts (LDLR). Rather than altering cholesterol levels in lipid raft fractions and thus disrupting lipid raft structure, lovastatin decreased Abeta generation through down-regulating geranylgeranyl-pyrophosphate dependent endocytosis pathway. The inhibition of APP endocytosis by treatment with lovastatin and reduction of APP levels in LDLR fractions by treatment with phenylarsine oxide (a general endocytosis inhibitor) support the involvement of APP endocytosis in APP distribution in LDLR fractions and subsequent APP beta-cleavage. Moreover, lovastatin-mediated down-regulation of endocytosis regulators, such as early endosomal antigen 1, dynamin-1, and phosphatidylinositol 3-kinase activity, indicates that lovastatin modulates APP endocytosis possibly through its pleiotropic effects on endocytic regulators. Collectively, these data report that lovastatin mediates inhibition of LDLR distribution and beta-cleavage of APP in a geranylgeranyl-pyrophosphate and endocytosis-dependent manner.
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Affiliation(s)
- Je-Seong Won
- Department of Pathology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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IYER ANANDKRISHNANV, TRAN KIENT, GRIFFITH LINDA, WELLS ALAN. Cell surface restriction of EGFR by a tenascin cytotactin-encoded EGF-like repeat is preferential for motility-related signaling. J Cell Physiol 2007; 214:504-12. [PMID: 17708541 PMCID: PMC2963575 DOI: 10.1002/jcp.21232] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The 14th EGFL-repeat (Ten14) of human tenascin cytotactin activates the epidermal growth factor receptor (EGFR) with micromolar affinity; however, unlike EGF, Ten14-mediated activation of EGFR does not lead to receptor internalization. As the divergent signaling pathways downstream of EGFR have been shown to be triggered from plasma membrane and cytosolic locales, we investigated whether Ten14-mediated surface restriction of EGFR resulted in altered biochemical and cellular responses as compared to EGF. Molecules associated with migratory cascades were activated to a relatively greater extent in response to Ten14, with very weak activation of proliferation-associated cascades. Activation of phospholipase C gamma (PLCgamma) and m-calpain, associated with lamellipod protrusion and tail retraction, respectively, were noted at even at sub-saturating doses of Ten14. However, activation of ERK/MAPK, p90RSK, and Elk1, factors affecting proliferation, remained low even at high Ten14 concentrations. Similar activation profiles were observed for EGF-treated cells at 4 degrees C, a maneuver that limits receptor internalization. We demonstrate a concurrent effect of such altered signaling on biophysical responses-sustained migration was observed at levels of Ten14 that activated PLCgamma, but did not stimulate proliferation significantly. Here, we present a novel class of EGFR ligands that can potentially signal as a part of the extracellular matrix, triggering specific intracellular signaling cascades leading to a directed cellular response from an otherwise pleiotropic receptor. This work extends the signaling paradigm of EGFL repeat being presented in a restricted fashion as part of the extracellular matrix.
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Affiliation(s)
| | - KIEN T. TRAN
- Department of Pathology, University of Pittsburgh, Pittsburgh, Penssylvania
| | - LINDA GRIFFITH
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - ALAN WELLS
- Department of Pathology, University of Pittsburgh, Pittsburgh, Penssylvania
- Pittsburgh VA Medical Center, Pittsburgh, Penssylvania
- Correspondence to: Alan Wells, Department of Pathology, School of Medicine, University of Pittsburgh, 3550 Terrace St., Scaife Hall, S-713, Pittsburgh, PA 15261.
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Das M, Scappini E, Martin NP, Wong KA, Dunn S, Chen YJ, Miller SLH, Domin J, O'Bryan JP. Regulation of neuron survival through an intersectin-phosphoinositide 3'-kinase C2beta-AKT pathway. Mol Cell Biol 2007; 27:7906-17. [PMID: 17875942 PMCID: PMC2169155 DOI: 10.1128/mcb.01369-07] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
While endocytosis attenuates signals from plasma membrane receptors, recent studies suggest that endocytosis also serves as a platform for the compartmentalized activation of cellular signaling pathways. Intersectin (ITSN) is a multidomain scaffolding protein that regulates endocytosis and has the potential to regulate various biochemical pathways through its multiple, modular domains. To address the biological importance of ITSN in regulating cellular signaling pathways versus in endocytosis, we have stably silenced ITSN expression in neuronal cells by using short hairpin RNAs. Decreasing ITSN expression dramatically increased apoptosis in both neuroblastoma cells and primary cortical neurons. Surprisingly, the loss of ITSN did not lead to major defects in the endocytic pathway. Yeast two-hybrid analysis identified class II phosphoinositide 3'-kinase C2beta (PI3K-C2beta) as an ITSN binding protein, suggesting that ITSN may regulate a PI3K-C2beta-AKT survival pathway. ITSN associated with PI3K-C2beta on a subset of endomembrane vesicles and enhanced both basal and growth factor-stimulated PI3K-C2beta activity, resulting in AKT activation. The use of pharmacological inhibitors, dominant negatives, and rescue experiments revealed that PI3K-C2beta and AKT were epistatic to ITSN. This study represents the first demonstration that ITSN, independent of its role in endocytosis, regulates a critical cellular signaling pathway necessary for cell survival.
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Affiliation(s)
- Margaret Das
- Laboratory of Signal Transduction, Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709, USA
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Scappini E, Koh TW, Martin NP, O'Bryan JP. Intersectin enhances huntingtin aggregation and neurodegeneration through activation of c-Jun-NH2-terminal kinase. Hum Mol Genet 2007; 16:1862-71. [PMID: 17550941 DOI: 10.1093/hmg/ddm134] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Huntingon's disease is a progressive neurodegenerative disease arising from expansion of a polyglutamine (polyQ) tract in the protein huntingtin (Htt) resulting in aggregation of mutant Htt into nuclear and/or cytosolic inclusions in neurons. Mutant Htt affects multiple processes including protein degradation, transcription, signal transduction, fast axonal transport and endocytosis [reviewed in Ross, C.A. and Poirier, M.A. (2005) Opinion: what is the role of protein aggregation in neurodegeneration? Nat. Rev. Mol. Cell. Biol., 6, 891-898]. Here, we report that the endocytic and signal transduction scaffold intersectin (ITSN) increased aggregate formation by mutant Htt through activation of the c-Jun-NH(2)-terminal kinase (JNK)-MAPK pathway. Conversely, silencing ITSN or inhibiting JNK attenuated aggregate formation. Using a Drosophila model for polyQ repeat disease, we observed that ITSN enhanced polyQ-mediated neurotoxicity. A reciprocal relationship was observed between ITSN and Htt. While ITSN enhanced Htt aggregation and toxicity, Htt, in turn, inhibited the cooperativity between ITSN and the epidermal growth factor receptor signal transduction pathway. Finally, we observed that ITSN overexpression enhanced aggregation of polyQ-expanded androgen receptor (AR) as well as wild-type versions of both Htt and AR suggesting a broader involvement of ITSN in neurodegenerative diseases through destabilization of polyQ-containing proteins.
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Affiliation(s)
- Erica Scappini
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
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Predescu SA, Predescu DN, Knezevic I, Klein IK, Malik AB. Intersectin-1s regulates the mitochondrial apoptotic pathway in endothelial cells. J Biol Chem 2007; 282:17166-78. [PMID: 17405881 DOI: 10.1074/jbc.m608996200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Intersectins (ITSNs) are multidomain adaptor proteins implicated in endocytosis, regulation of actin polymerization, and Ras/MAPK signaling. We have previously shown that ITSN-1s is required for caveolae fission and internalization in endothelial cells (ECs). In the present study, using small interfering RNA to knock down ITSN-1s protein expression, we demonstrate a novel role of ITSN-1s as a key antiapoptotic protein. Knockdown of ITSN-1s in ECs activated the mitochondrial pathway of apoptosis as determined by genomic DNA fragmentation, extensive mitochondrial fission, activation of the proapoptotic proteins BAK and BAX, and cytochrome c efflux from mitochondria. ITSN-1 knockdown acts as a proapoptotic signal that causes mitochondrial outer membrane permeabilization, dissipation of the mitochondrial membrane potential, and generation of reactive oxygen species. These effects were secondary to decreased activation of Erk1/2 and its direct activator MEK. Bcl-X(L) overexpression prevented BAX activation and the apoptotic ECs death induced by suppression of ITSN-1s. Our findings demonstrate a novel role of ITSN-1s as a negative regulator of the mitochondrial pathway-dependent apoptosis secondary to activation of the Erk1/2 survival signaling pathway.
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Affiliation(s)
- Sanda A Predescu
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.
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Evergren E, Gad H, Walther K, Sundborger A, Tomilin N, Shupliakov O. Intersectin is a negative regulator of dynamin recruitment to the synaptic endocytic zone in the central synapse. J Neurosci 2007; 27:379-90. [PMID: 17215399 PMCID: PMC6672076 DOI: 10.1523/jneurosci.4683-06.2007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 11/27/2006] [Accepted: 11/27/2006] [Indexed: 11/21/2022] Open
Abstract
Intersectin is a multidomain dynamin-binding protein implicated in numerous functions in the nervous system, including synapse formation and endocytosis. Here, we demonstrate that during neurotransmitter release in the central synapse, intersectin, like its binding partner dynamin, is redistributed from the synaptic vesicle pool to the periactive zone. Acute perturbation of the intersectin-dynamin interaction by microinjection of either intersectin antibodies or Src homology 3 (SH3) domains inhibited endocytosis at the fission step. Although the morphological effects induced by the different reagents were similar, antibody injections resulted in a dramatic increase in dynamin immunoreactivity around coated pits and at constricted necks, whereas synapses microinjected with the GST (glutathione S-transferase)-SH3C domain displayed reduced amounts of dynamin in the neck region. Our data suggest that intersectin controls the amount of dynamin released from the synaptic vesicle cluster to the periactive zone and that it may regulate fission of clathrin-coated intermediates.
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Affiliation(s)
- Emma Evergren
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Helge Gad
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Kristin Walther
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Anna Sundborger
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Nikolay Tomilin
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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Zielak AE, Forde N, Park SDE, Doohan F, Coussens PM, Smith GW, Ireland JJ, Lonergan P, Evans ACO. Identification of novel genes associated with dominant follicle development in cattle. Reprod Fertil Dev 2007; 19:967-75. [DOI: 10.1071/rd07102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2007] [Accepted: 09/16/2007] [Indexed: 11/23/2022] Open
Abstract
Follicle development is regulated by the interaction of endocrine and intrafollicular factors, as well as by numerous intracellular pathways, which involves the transcription of new genes, although not all are known. The aim of the present study was to determine the expression of a set of unknown genes identified by bovine cDNA microarray analysis in theca and granulosa cells of dominant and subordinate follicles, collected at a single stage of the first follicular wave using quantitative real-time polymerase chain reaction. Differences were further examined at three stages of the follicular wave (emergence, selection and dominance) and bioinformatics tools were used to identify these originally unknown sequences. The suggested name function and proposed role for the novel genes identified are as follows: MRPL41 and VDAC2, involved in apoptosis (dominant follicle development); TBC1D1 stimulates cell differentiation (growth associated with dominant follicle selection and development); STX7, promotes phagocytosis of cells (subordinate follicle regression); and SPC22 and EHD3, intracellular signalling (subordinate follicle regression). In conclusion, we have identified six novel genes that have not been described previously in ovarian follicles that are dynamically regulated during dominant follicle development and presumably help mediate intracellular signalling, cell differentiation, apoptosis and phagocytosis, events critical to follicular development.
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Wilmot B, McWeeney SK, Nixon RR, Montine TJ, Laut J, Harrington CA, Kaye JA, Kramer PL. Translational gene mapping of cognitive decline. Neurobiol Aging 2006; 29:524-41. [PMID: 17174450 PMCID: PMC2684335 DOI: 10.1016/j.neurobiolaging.2006.11.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 11/14/2006] [Accepted: 11/16/2006] [Indexed: 11/21/2022]
Abstract
The ability to maintain cognitive function during aging is a complex process subject to genetic and environmental influences. Alzheimer's disease (AD) is the most common disorder causing cognitive decline among the elderly. Among those with AD, there is broad variation in the relationship between AD neuropathology and clinical manifestations of dementia. Differences in expression of genes involved in neural processing pathways may contribute to individual differences in maintenance of cognitive function. We performed whole genome expression profiling of RNA obtained from frontal cortex of clinically non-demented and AD subjects to identify genes associated with brain aging and cognitive decline. Genetic mapping information and biological function annotation were incorporated to highlight genes of particular interest. The candidate genes identified in this study were compared with those from two other studies in different tissues to identify common underlying transcriptional profiles. In addition to confirming sweeping transcriptomal differences documented in previous studies of cognitive decline, we present new evidence for up-regulation of actin-related processes and down-regulation of translation, RNA processing and localization, and vesicle-mediated transport in individuals with cognitive decline.
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Affiliation(s)
- Beth Wilmot
- Department of Molecular and Medical Genetics, Oregon Health and Sciences University, Portland, OR 97239, USA.
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Ivanov VN, Hei TK. Dual treatment with COX-2 inhibitor and sodium arsenite leads to induction of surface Fas Ligand expression and Fas-Ligand-mediated apoptosis in human melanoma cells. Exp Cell Res 2006; 312:1401-17. [PMID: 16487513 PMCID: PMC4376328 DOI: 10.1016/j.yexcr.2006.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 12/12/2005] [Accepted: 01/09/2006] [Indexed: 11/18/2022]
Abstract
Most human melanomas express Fas receptor on the cell surface, and treatment with exogenous Fas Ligand (FasL) efficiently induces apoptosis of these cells. In contrast, endogenous surface expression of FasL is suppressed in Fas-positive melanomas. We report here the use of a combination of sodium arsenite, an inhibitor of NF-kappaB activation, and NS398, a cyclooxygenase-2 (COX-2) inhibitor, for restoration of the surface FasL expression. We observed a large increase of Fas-mediated apoptosis in Fas-positive melanomas. This was due to induction of FasL surface expression and increased susceptibility to Fas death signaling after arsenite and NS398 treatment. Furthermore, silencing COX-2 expression by specific RNAi also effectively increased surface FasL expression following arsenite treatment. Upregulation of the surface FasL levels was based on an increase in the efficiency of translocation to the cell surface and stabilization of FasL protein on the cell surface, rather than on acceleration of the FasL gene transcription. Data obtained demonstrate that the combination of arsenite with inhibitors of COX-2 may affect the target cancer cells via induction of FasL-mediated death signaling.
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Affiliation(s)
- Vladimir N Ivanov
- Center for Radiological Research, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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Sakiyama H, Takahashi M, Yamamoto T, Teshima T, Lee SH, Miyamoto Y, Misonou Y, Taniguchi N. The Internalization and Metabolism of 3-Deoxyglucosone in Human Umbilical Vein Endothelial Cells. ACTA ACUST UNITED AC 2006; 139:245-53. [PMID: 16452312 DOI: 10.1093/jb/mvj017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
3-Deoxyglucosone (3-DG), a dicarbonyl compound produced by glycation, plays a role in the modification and cross-linking of long-lived proteins. We synthesized [3H]3-DG from [3H]glucose and developed an internalization assay system using HPLC to examine its cellular metabolism. When smooth muscle cells or human umbilical vein endothelial cells were incubated with [3H]3-DG, it was found that [3H]3-DG was internalized by cells in a time dependent manner. The rate of internalization was reduced when the cells were incubated at 4 degrees C or treated with phenylarsine oxide (PAO). By monitoring [3H]3-DG taken up by cells, it was confirmed that 3-DG is reduced to 3-deoxyfructose (3-DF) and that this reaction was inhibited by an aldo-keto reductase inhibitor (ARI). The presence of 3-DG led to an increase in reactive oxygen species levels in the cells and subsequent apoptosis, and the effect was enhanced by pretreatment with ARI. These results suggest that 3-DG is internalized by cells and reduced to 3-DF by aldo-keto reductases, and that the internalized 3-DG is responsible for the production of intracellular oxidative stress.
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Affiliation(s)
- Haruhiko Sakiyama
- Department of Biochemistry, Osaka University Graduate School of Medicine, B1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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Abstract
The microvascular endothelial cell monolayer localized at the critical interface between the blood and vessel wall has the vital functions of regulating tissue fluid balance and supplying the essential nutrients needed for the survival of the organism. The endothelial cell is an exquisite “sensor” that responds to diverse signals generated in the blood, subendothelium, and interacting cells. The endothelial cell is able to dynamically regulate its paracellular and transcellular pathways for transport of plasma proteins, solutes, and liquid. The semipermeable characteristic of the endothelium (which distinguishes it from the epithelium) is crucial for establishing the transendothelial protein gradient (the colloid osmotic gradient) required for tissue fluid homeostasis. Interendothelial junctions comprise a complex array of proteins in series with the extracellular matrix constituents and serve to limit the transport of albumin and other plasma proteins by the paracellular pathway. This pathway is highly regulated by the activation of specific extrinsic and intrinsic signaling pathways. Recent evidence has also highlighted the importance of the heretofore enigmatic transcellular pathway in mediating albumin transport via transcytosis. Caveolae, the vesicular carriers filled with receptor-bound and unbound free solutes, have been shown to shuttle between the vascular and extravascular spaces depositing their contents outside the cell. This review summarizes and analyzes the recent data from genetic, physiological, cellular, and morphological studies that have addressed the signaling mechanisms involved in the regulation of both the paracellular and transcellular transport pathways.
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Affiliation(s)
- Dolly Mehta
- Center of Lung and Vascular Biology, Dept. of Pharmacology (M/C 868), University of Illinois, 835 S. Wolcott Avenue, Chicago, IL 60612, USA
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Naslavsky N, Caplan S. C-terminal EH-domain-containing proteins: consensus for a role in endocytic trafficking, EH? J Cell Sci 2005; 118:4093-101. [PMID: 16155252 DOI: 10.1242/jcs.02595] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The Eps15-homology (EH) domain is a highly conserved motif comprising ∼100 residues that is found in proteins from species as diverse as yeast and mammals. Proteins that have an EH domain can carry out a variety of crucial cellular functions ranging from regulation of the actin cytoskeleton, signal transduction and transcriptional regulation to control of the endocytic pathway. EH domains bind to proteins that contain the tripeptide asparagine-proline-phenylalanine (NPF). Although EH domains are typically found at the N-terminus, mammalian cells express four highly homologous C-terminal EH-domain-containing paralogs (EHD1-EHD4), which exhibit broad amino acid conservation throughout the entire sequence. These C-terminal EH-domain-containing proteins also contain a central coiled-coil region involved in oligomerization, as well as an N-terminal nucleotide-binding motif. Recent studies have identified an array of novel binding partners for EHD1-EHD4, including NPF-containing proteins, such as the divalent Rab4/5 effector rabenosyn 5, the cell fate determinant Numb, EH-binding protein 1 (EHBP1) and syndapins I and II. Interactions with the clathrin heavy-chain and components of the internalization machinery have also been described. Indeed, C-terminal EH-domain-containing proteins appear to regulate several key endocytic steps, including internalization and recycling. EHD1 and EHD4 control recycling by regulating the transport of receptors from the recycling compartment to the plasma membrane. EHD1, EHD2 and EHD4 have also been implicated in the internalization of receptors and their transport to early endosomes.
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Affiliation(s)
- Naava Naslavsky
- Department of Biochemistry and Molecular Biology and Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-5870, USA
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Yang XL, Huang YZ, Xiong WC, Mei L. Neuregulin-induced expression of the acetylcholine receptor requires endocytosis of ErbB receptors. Mol Cell Neurosci 2005; 28:335-46. [PMID: 15691714 DOI: 10.1016/j.mcn.2004.10.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 09/27/2004] [Accepted: 10/02/2004] [Indexed: 11/24/2022] Open
Abstract
Neuregulin-induced expression of the acetylcholine receptor (AChR) contributes to high concentration of the receptor at the neuromuscular junction (NMJ). Neuregulin-1 activates ErbB tyrosine kinases and subsequently intracellular kinases including Erk that is required for induced AChR expression. Recent studies demonstrate that ligand-induced internalization may regulate signaling of various receptor tyrosine kinases. However, the role of induced ErbB endocytosis in regulating AChR expression was unclear. Here we provide evidence that ErbB tyrosine kinases became rapidly internalized in response to neuregulin. The internalization required the kinase activity of ErbB proteins and involved a clathrin-dependent endocytic pathway. Moreover, neuregulin-induced Erk activation and AChR expression were attenuated when ErbB endocytosis was blocked. These results indicate that ErbB proteins undergo endocytosis in response to neuregulin, and this process is required for neuregulin signaling and induced AChR expression.
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Affiliation(s)
- Xiao-Li Yang
- Department of Neurobiology, University of Alabama at Birmingham, Civitan International Research Center, Birmingham, AL 35294, USA
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45
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Tsyba L, Skrypkina I, Rynditch A, Nikolaienko O, Ferenets G, Fortna A, Gardiner K. Alternative splicing of mammalian Intersectin 1: domain associations and tissue specificities. Genomics 2005; 84:106-13. [PMID: 15203208 DOI: 10.1016/j.ygeno.2004.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Accepted: 02/11/2004] [Indexed: 11/18/2022]
Abstract
The Intersectin 1 (ITSN1) protein functions in clathrin-mediated endocytosis and in MAP kinase signaling. The complex domain structure comprises two EH and five SH3 domains in the short isoform, plus RhoGEF, pleckstrin, and putative calcium-interaction domains in the long isoform. Alternative splicing of exon 20, affecting the SH3A domain, has been shown in rat and that of exons 25 + 26, affecting the SH3C domain, has been shown in human and rat. Here we report 7 novel splice variants of the human and mouse ITSN1 genes and demonstrate conservation of alternative splicing affecting SH3A and SH3C in mouse. The novel variants encode transcripts with altered EH domain spacing and RhoGEF domain structure and possible targets of nonsense-mediated decay. Eight and 16 protein variants of the short and long ITSN1 isoforms, respectively, are predicted. These isoforms likely serve to modulate the many complex protein interactions and functions of ITSN1.
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Affiliation(s)
- Lyudmyla Tsyba
- Institute of Molecular Biology and Genetics, 150 Zabolotnogo, Kyiv 03143, Ukraine
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46
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Yam JWP, Jin DY, So CW, Chan LC. Identification and characterization of EBP, a novel EEN binding protein that inhibits Ras signaling and is recruited into the nucleus by the MLL-EEN fusion protein. Blood 2004; 103:1445-53. [PMID: 14551139 DOI: 10.1182/blood-2003-07-2452] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AbstractThe chimeric MLL-EEN fusion protein is created as a result of chromosomal translocation t(11;19)(q23;p13). EEN, an Src homology 3 (SH3) domain–containing protein in the endophilin family, has been implicated in endocytosis, although little is known about its role in leukemogenesis mediated by the MLL-EEN fusion protein. In this study, we have identified and characterized EBP, a novel EEN binding protein that interacts with the SH3 domain of EEN through a proline-rich motif PPERP. EBP is a ubiquitous protein that is normally expressed in the cytoplasm but is recruited to the nucleus by MLL-EEN with a punctate localization pattern characteristic of the MLL chimeric proteins. EBP interacts simultaneously with EEN and Sos, a guanine-nucleotide exchange factor for Ras. Coexpressoin of EBP with EEN leads to suppression of Ras-induced cellular transformation and Ras-mediated activation of Elk-1. Taken together, our findings suggest a new mechanism for MLL-EEN–mediated leukemogenesis in which MLL-EEN interferes with the Ras-suppressing activities of EBP through direct interaction.
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Abstract
Internalization of receptors, lipids, pathogens, and other cargo at the plasma membrane involves several different pathways and requires coordinated interactions between a variety of protein and lipid molecules. The actin cytoskeleton is an integral part of the cell cortex, and there is growing evidence that F-actin plays a direct role in these endocytic events. Genetic studies in yeast have firmly established a functional connection between actin and endocytosis. Identification of several proteins that may function at the interface between actin and the endocytic machinery has provided further evidence for this association in both yeast and mammalian cells. Several of these proteins are directly involved in regulating actin assembly and could thus harness forces produced during actin polymerization to facilitate specific steps in the endocytic process. Recent microscopy studies in mammalian cells provide powerful evidence that localized recruitment and polymerization of actin occurs at endocytic sites. In this review, we focus on progress made in elucidating the functions of the actin cytoskeleton in endocytosis.
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Affiliation(s)
- Asa E Y Engqvist-Goldstein
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA
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48
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Abstract
Exogenously and endogenously originated signals are propagated within the cell by functional and physical networks of proteins, leading to numerous biological outcomes. Many protein-protein interactions take place between binding domains and short peptide motifs. Frequently, these interactions are inducible by upstream signaling events, in which case one of the two binding surfaces may be created by a posttranslational modification. Here, we discuss two protein networks. One, the EH-network, is based on the Eps15 homology (EH) domain, which binds to peptides containing the sequence Asp-Pro-Phe (NPF). The other, which we define as the monoubiquitin (mUb) network, relies on monoubiquitination, which is emerging as an important posttranslational modification that regulates protein function. Both networks were initially implicated in the control of plasma membrane receptor endocytosis and in the regulation of intracellular trafficking routes. The ramifications of these two networks, however, appear to extend into many other aspects of cell physiology as well, such as transcriptional regulation, actin cytoskeleton remodeling, and DNA repair. The focus of this review is to integrate available knowledge of the EH- and mUb networks with predictions of genetic and physical interactions stemming from functional genomics approaches.
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Affiliation(s)
- Simona Polo
- Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
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Mohney RP, Das M, Bivona TG, Hanes R, Adams AG, Philips MR, O'Bryan JP. Intersectin activates Ras but stimulates transcription through an independent pathway involving JNK. J Biol Chem 2003; 278:47038-45. [PMID: 12970366 DOI: 10.1074/jbc.m303895200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intersectin (ITSN) is a molecular scaffold involved in regulating endocytosis and mitogenic signaling. We previously demonstrated that ITSN transformed rodent fibroblasts, accelerated hormone-induced maturation of Xenopus oocytes, and activated the Elk-1 transcription factor through an MEK- and Erk-independent mechanism. We now demonstrate that ITSN complexes with the Ras guanine nucleotide exchange factor Sos1 leading to increased RasGTP levels. Using fluorescence resonant energy transfer analysis, we demonstrate that ITSN complexes with Ras in living cells leading to Ras activation on intracellular vesicles. These vesicles contain epidermal growth factor receptor but are distinct from transferrin-positive vesicles. However, Ras is not required for ITSN stimulation of transcription. Rather, we demonstrate that ITSN signals through JNK to activate Elk-1. Although ITSN activation of Elk-1 was Ras-independent, ITSN cooperates with Ras to synergistically activate JNK. These findings indicate that ITSN activates multiple intracellular signaling pathways and suggest that this adaptor protein may coordinately regulate the activity of these pathways in vivo.
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Affiliation(s)
- Robert P Mohney
- Laboratory of Signal Transduction, National Institute of Environmental Health Services, NIH/DHHS, Building 101, Research Triangle Park, NC 27709, USA
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50
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González-Gaitán M. Signal dispersal and transduction through the endocytic pathway. Nat Rev Mol Cell Biol 2003; 4:213-24. [PMID: 12612640 DOI: 10.1038/nrm1053] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
During cell signalling, information that is encoded by ligands travels from one place, the source, to another, the target, where signals are transduced by receptors. Evidence has emerged recently that uncovers a role for the endocytic pathway in the secretion of ligands at the source, their dispersion through developing target tissues and the transduction of the signals from endocytic compartments. As a result, endosomes have become the focus of attention in cell-cell communication studies.
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Affiliation(s)
- Marcos González-Gaitán
- Max-Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D01307 Dresden, Germany.
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