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Tang T, Hasan M, Capelluto DGS. Phafins Are More Than Phosphoinositide-Binding Proteins. Int J Mol Sci 2023; 24:ijms24098096. [PMID: 37175801 PMCID: PMC10178739 DOI: 10.3390/ijms24098096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
Phafins are PH (Pleckstrin Homology) and FYVE (Fab1, YOTB, Vac1, and EEA1) domain-containing proteins. The Phafin protein family is classified into two groups based on their sequence homology and functional similarity: Phafin1 and Phafin2. This protein family is unique because both the PH and FYVE domains bind to phosphatidylinositol 3-phosphate [PtdIns(3)P], a phosphoinositide primarily found in endosomal and lysosomal membranes. Phafin proteins act as PtdIns(3)P effectors in apoptosis, endocytic cargo trafficking, and autophagy. Additionally, Phafin2 is recruited to macropinocytic compartments through coincidence detection of PtdIns(3)P and PtdIns(4)P. Membrane-associated Phafins serve as adaptor proteins that recruit other binding partners. In addition to the phosphoinositide-binding domains, Phafin proteins present a poly aspartic acid motif that regulates membrane binding specificity. In this review, we summarize the involvement of Phafins in several cellular pathways and their potential physiological functions while highlighting the similarities and differences between Phafin1 and Phafin2. Besides, we discuss research perspectives for Phafins.
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Affiliation(s)
- Tuoxian Tang
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mahmudul Hasan
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Daniel G S Capelluto
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA
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2
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Ren Y, Wang C, Wang H, Chang Q, Guo D, Wang X. Identification of zebrafish PLEKHF2 presents in egg/embryos as an antibacterial protein. FISH & SHELLFISH IMMUNOLOGY 2022; 127:925-932. [PMID: 35863537 DOI: 10.1016/j.fsi.2022.07.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 07/06/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
PLEKHF2 proteins are widespread in animals, but their functions and mechanisms remain poorly defined. Here we clearly demonstrate that PLEKHF2 is a newly identified present abundantly in the eggs/embryos of zebrafish. We also show that recombinant PLEKHF2 acts as a pattern recognition receptor capable of identifying the bacterial signature molecule PGN, LPS, and LTA, binding the bacteria, and functions as an antibacterial effector directly killing the bacteria. In brief, these results indicate that PLEKHF2 is an antibacterial protein, a novel role assigned to PLEKHF2 proteins.
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Affiliation(s)
- Yiqing Ren
- Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Chunqiu Wang
- Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Hao Wang
- Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Qingqi Chang
- Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Dongqiu Guo
- Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Xia Wang
- Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China.
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3
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The PH Domain and C-Terminal polyD Motif of Phafin2 Exhibit a Unique Concurrence in Animals. MEMBRANES 2022; 12:membranes12070696. [PMID: 35877899 PMCID: PMC9324892 DOI: 10.3390/membranes12070696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 01/27/2023]
Abstract
Phafin2, a member of the Phafin family of proteins, contributes to a plethora of cellular activities including autophagy, endosomal cargo transportation, and macropinocytosis. The PH and FYVE domains of Phafin2 play key roles in membrane binding, whereas the C-terminal poly aspartic acid (polyD) motif specifically autoinhibits the PH domain binding to the membrane phosphatidylinositol 3-phosphate (PtdIns3P). Since the Phafin2 FYVE domain also binds PtdIns3P, the role of the polyD motif remains unclear. In this study, bioinformatics tools and resources were employed to determine the concurrence of the PH-FYVE module with the polyD motif among Phafin2 and PH-, FYVE-, or polyD-containing proteins from bacteria to humans. FYVE was found to be an ancient domain of Phafin2 and is related to proteins that are present in both prokaryotes and eukaryotes. Interestingly, the polyD motif only evolved in Phafin2 and PH- or both PH-FYVE-containing proteins in animals. PolyD motifs are absent in PH domain-free FYVE-containing proteins, which usually display cellular trafficking or autophagic functions. Moreover, the prediction of the Phafin2-interacting network indicates that Phafin2 primarily cross-talks with proteins involved in autophagy, protein trafficking, and neuronal function. Taken together, the concurrence of the polyD motif with the PH domain may be associated with complex cellular functions that evolved specifically in animals.
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Ellena JF, Tang TX, Shanaiah N, Capelluto DGS. Backbone 1H, 15N, and 13C resonance assignments of the Phafin2 pleckstrin homology domain. BIOMOLECULAR NMR ASSIGNMENTS 2022; 16:27-30. [PMID: 34739631 PMCID: PMC9068824 DOI: 10.1007/s12104-021-10054-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/27/2021] [Indexed: 05/27/2023]
Abstract
Phafin2 is a peripheral protein that triggers cellular signaling from endosomal and lysosomal compartments. The specific subcellular localization of Phafin2 is mediated by the presence of a tandem of phosphatidylinositol 3-phosphate (PtdIns3P)-binding domains, the pleckstrin homology (PH) and the Fab-1, YOTB, Vac1, and EEA1 (FYVE) domains. The requirement for both domains for binding to PtdIns3P still remains unclear. To understand the molecular interactions of the Phafin2 PH domain in detail, we report its nearly complete 1H, 15N, and 13C backbone resonance assignments.
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Affiliation(s)
- Jeffrey F Ellena
- Biomolecular Magnetic Resonance Facility, University of Virginia, Charlottesville, VA, 22904, USA
| | - Tuo-Xian Tang
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | | | - Daniel G S Capelluto
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA.
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5
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The C-terminal acidic motif of Phafin2 inhibits PH domain binding to phosphatidylinositol 3-phosphate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183230. [PMID: 32126233 DOI: 10.1016/j.bbamem.2020.183230] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 02/15/2020] [Accepted: 02/18/2020] [Indexed: 02/07/2023]
Abstract
Changes in membrane curvature are required to control the function of subcellular compartments; malfunctions of such processes are associated with a wide range of human diseases. Membrane remodeling often depends upon the presence of phosphoinositides, which recruit protein effectors for a variety of cellular functions. Phafin2 is a phosphatidylinositol 3-phosphate (PtdIns3P)-binding effector involved in endosomal and lysosomal membrane-associated signaling. Both the Phafin2 PH and the FYVE domains bind PtdIns3P, although their redundant function in the protein is unclear. Through a combination of lipid-binding assays, we found that, unlike the FYVE domain, recognition of the PH domain to PtdIns3P requires a lipid bilayer. Using site-directed mutagenesis and truncation constructs, we discovered that the Phafin2 FYVE domain is constitutive for PtdIns3P binding, whereas PH domain binding to PtdIns3P is autoinhibited by a conserved C-terminal acidic motif. These findings suggest that binding of the Phafin2 PH domain to PtdIns3P in membrane compartments occurs through a highly regulated mechanism. Potential mechanisms are discussed throughout this report.
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Tang T, Jo A, Deng J, Ellena JF, Lazar IM, Davis RM, Capelluto DGS. Structural, thermodynamic, and phosphatidylinositol 3-phosphate binding properties of Phafin2. Protein Sci 2017; 26:814-823. [PMID: 28152563 PMCID: PMC5368057 DOI: 10.1002/pro.3128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/06/2017] [Accepted: 01/11/2017] [Indexed: 02/02/2023]
Abstract
Phafin2 is a phosphatidylinositol 3-phosphate (PtdIns(3)P) binding protein involved in the regulation of endosomal cargo trafficking and lysosomal induction of autophagy. Binding of Phafin2 to PtdIns(3)P is mediated by both its PH and FYVE domains. However, there are no studies on the structural basis, conformational stability, and lipid interactions of Phafin2 to better understand how this protein participates in signaling at the surface of endomembrane compartments. Here, we show that human Phafin2 is a moderately elongated monomer of ∼28 kDa with an intensity-average hydrodynamic diameter of ∼7 nm. Circular dichroism (CD) analysis indicates that Phafin2 exhibits an α/β structure and predicts ∼40% random coil content in the protein. Heteronuclear NMR data indicates that a unique conformation of Phafin2 is present in solution and dispersion of resonances suggests that the protein exhibits random coiled regions, in agreement with the CD data. Phafin2 is stable, displaying a melting temperature of 48.4°C. The folding-unfolding curves, obtained using urea- and guanidine hydrochloride-mediated denaturation, indicate that Phafin2 undergoes a two-state native-to-denatured transition. Analysis of these transitions shows that the free energy change for urea- and guanidine hydrochloride-induced Phafin2 denaturation in water is ∼4 kcal mol-1 . PtdIns(3)P binding to Phafin2 occurs with high affinity, triggering minor conformational changes in the protein. Taken together, these studies represent a platform for establishing the structural basis of Phafin2 molecular interactions and the role of the two potentially redundant PtdIns(3)P-binding domains of the protein in endomembrane compartments.
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Affiliation(s)
- Tuo‐Xian Tang
- Protein Signaling Domains Laboratory, Department of Biological SciencesBiocomplexity Institute, and Center for Soft Matter and Biological Physics, Virginia TechBlacksburgVirginia24061
| | - Ami Jo
- Department of Chemical EngineeringVirginia TechBlacksburgVirginia24061
| | - Jingren Deng
- Department of Biological SciencesVirginia TechBlacksburgVirginia24061
| | - Jeffrey F. Ellena
- Biomolecular Magnetic Resonance Facility, University of VirginiaCharlottesvilleVirginia22904
| | - Iulia M. Lazar
- Department of Biological SciencesVirginia TechBlacksburgVirginia24061
| | - Richey M. Davis
- Department of Chemical EngineeringVirginia TechBlacksburgVirginia24061
| | - Daniel G. S. Capelluto
- Protein Signaling Domains Laboratory, Department of Biological SciencesBiocomplexity Institute, and Center for Soft Matter and Biological Physics, Virginia TechBlacksburgVirginia24061
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Kariuki SN, Ghodke-Puranik Y, Dorschner JM, Chrabot BS, Kelly JA, Tsao BP, Kimberly RP, Alarcón-Riquelme ME, Jacob CO, Criswell LA, Sivils KL, Langefeld CD, Harley JB, Skol AD, Niewold TB. Genetic analysis of the pathogenic molecular sub-phenotype interferon-alpha identifies multiple novel loci involved in systemic lupus erythematosus. Genes Immun 2015; 16:15-23. [PMID: 25338677 PMCID: PMC4305028 DOI: 10.1038/gene.2014.57] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/10/2014] [Accepted: 09/11/2014] [Indexed: 12/13/2022]
Abstract
Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by inflammation of multiple organ systems and dysregulated interferon responses. SLE is both genetically and phenotypically heterogeneous, greatly reducing the power of case-control studies in SLE. Elevated circulating interferon-alpha (IFN-α) is a stable, heritable trait in SLE, which has been implicated in primary disease pathogenesis. About 40-50% of patients have high IFN-α, and high levels correspond with clinical differences. To study genetic heterogeneity in SLE, we performed a case-case study comparing patients with high vs low IFN-α in over 1550 SLE cases, including genome-wide association study and replication cohorts. In meta-analysis, the top associations in European ancestry were protein kinase, cyclic GMP-dependent, type I (PRKG1) rs7897633 (P(Meta) = 2.75 × 10(-8)) and purine nucleoside phosphorylase (PNP) rs1049564 (P(Meta) = 1.24 × 10(-7)). We also found evidence for cross-ancestral background associations with the ankyrin repeat domain 44 (ANKRD44) and pleckstrin homology domain containing, family F member 2 gene (PLEKHF2) loci. These loci have not been previously identified in case-control SLE genetic studies. Bioinformatic analyses implicated these loci functionally in dendritic cells and natural killer cells, both of which are involved in IFN-α production in SLE. As case-control studies of heterogeneous diseases reach a limit of feasibility with respect to subject number and detectable effect size, the study of informative pathogenic sub-phenotypes becomes an attractive strategy for genetic discovery in complex disease.
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Affiliation(s)
| | | | - Jessica M. Dorschner
- Department of Immunology and Division of Rheumatology, Mayo Clinic, Rochester, MN
| | - Beverly S. Chrabot
- Gwen Knapp Center for Lupus Research, University of Chicago, Chicago, IL
| | - Jennifer A. Kelly
- Arthritis & Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK
| | - Betty P. Tsao
- Department of Medicine, University of California, Los Angeles, CA
| | | | - Marta E. Alarcón-Riquelme
- Arthritis & Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK
- GENYO. Centre for Genomics and Oncological Research: Pfizer / University of Granada / Andalusian Regional Government
| | - Chaim O. Jacob
- Department of Medicine, University of Southern California, Los Angeles, CA
| | - Lindsey A. Criswell
- Rosalind Russell / Ephraim P. Engleman Rheumatology Research Center, University of California, San Francisco, CA
| | - Kathy L. Sivils
- Arthritis & Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK
| | - Carl D. Langefeld
- Department of Biostatistical Sciences, Wake Forest University, Winston-Salem, NC
| | - John B. Harley
- Cincinnati Children’s Hospital Medical Center and Cincinnati VA Medical Center, Cincinnati, OH
| | - Andrew D. Skol
- Department of Human Genetics, University of Chicago, Chicago, IL
| | - Timothy B. Niewold
- Department of Immunology and Division of Rheumatology, Mayo Clinic, Rochester, MN
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Matsuda-Lennikov M, Suizu F, Hirata N, Hashimoto M, Kimura K, Nagamine T, Fujioka Y, Ohba Y, Iwanaga T, Noguchi M. Lysosomal interaction of Akt with Phafin2: a critical step in the induction of autophagy. PLoS One 2014; 9:e79795. [PMID: 24416124 PMCID: PMC3885392 DOI: 10.1371/journal.pone.0079795] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 09/25/2013] [Indexed: 12/22/2022] Open
Abstract
Autophagy is an evolutionarily conserved mechanism for the gross disposal of intracellular proteins in mammalian cells and dysfunction in this pathway has been associated with human disease. Although the serine threonine kinase Akt is suggested to play a role in this process, little is known about the molecular mechanisms by which Akt induces autophagy. Using a yeast two-hybrid screen, Phafin2 (EAPF or PLEKHF2), a lysosomal protein with a unique structure of N-terminal PH (pleckstrin homology) domain and C-terminal FYVE (Fab 1, YOTB, Vac 1, and EEA1) domain was found to interact with Akt. A sucrose gradient fractionation experiment revealed that both Akt and Phafin2 co-existed in the same lysosome enriched fraction after autophagy induction. Confocal microscopic analysis and BiFC analysis demonstrated that both Akt and Phafin2 accumulate in the lysosome after induction of autophagy. BiFC analysis using PtdIns (3)P interaction defective mutant of Phafin2 demonstrated that lysosomal accumulation of the Akt-Phafin2 complex and subsequent induction of autophagy were lysosomal PtdIns (3)P dependent events. Furthermore, in murine macrophages, both Akt and Phafin2 were required for digestion of fluorescent bacteria and/or LPS-induced autophagy. Taken together, these findings establish that lysosomal accumulation of Akt and Phafin2 is a critical step in the induction of autophagy via an interaction with PtdIns (3)P.
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Affiliation(s)
- Mami Matsuda-Lennikov
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Futoshi Suizu
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Noriyuki Hirata
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Manabu Hashimoto
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Kohki Kimura
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Tadashi Nagamine
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Yoichiro Fujioka
- Laboratory of Pathophysiology and Signal Transduction, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Yusuke Ohba
- Laboratory of Pathophysiology and Signal Transduction, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Toshihiko Iwanaga
- Laboratory of Histology and Cytology, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
| | - Masayuki Noguchi
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
- * E-mail:
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Raiborg C, Schink KO, Stenmark H. Class III phosphatidylinositol 3-kinase and its catalytic product PtdIns3P in regulation of endocytic membrane traffic. FEBS J 2013; 280:2730-42. [PMID: 23289851 DOI: 10.1111/febs.12116] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 12/20/2012] [Accepted: 12/24/2012] [Indexed: 01/01/2023]
Abstract
Endocytosis and subsequent membrane traffic through endosomes are cellular processes that are integral to eukaryotic evolution, and numerous human diseases are associated with their dysfunction. Consequently, it is important to untangle the molecular machineries that regulate membrane dynamics and protein flow in the endocytic pathway. Central in this context is class III phosphatidylinositol 3-kinase, an evolutionarily conserved enzyme complex that phosphorylates phosphatidylinositol into phosphatidylinositol 3-phosphate. Phosphatidylinositol 3-phosphate recruits specific effector proteins, most of which contain FYVE or PX domains, to promote endocytosis, endosome fusion, endosome motility and endosome maturation, as well as cargo sorting to lysosomes, the biosynthetic pathway or the plasma membrane. Here we review the functions of key phosphatidylinositol 3-phosphate effectors in regulation of endocytic membrane dynamics and protein sorting.
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Affiliation(s)
- Camilla Raiborg
- Centre for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, Montebello, Norway
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10
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Pedersen NM, Raiborg C, Brech A, Skarpen E, Roxrud I, Platta HW, Liestøl K, Stenmark H. The PtdIns3P-binding protein Phafin 2 mediates epidermal growth factor receptor degradation by promoting endosome fusion. Traffic 2012; 13:1547-63. [PMID: 22816767 DOI: 10.1111/j.1600-0854.2012.01400.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 07/17/2012] [Accepted: 07/20/2012] [Indexed: 12/16/2022]
Abstract
Phosphatidylinositol 3-phosphate (PtdIns3P) orchestrates endosomal cargo transport, fusion and motility by recruiting FYVE or PX domain-containing effector proteins to endosomal membranes. In an attempt to discover novel PtdIns3P effectors involved in the termination of growth factor receptor signalling, we performed an siRNA screen for epidermal growth factor (EGF) degradation, targeting FYVE and PX domain proteins in the human proteome. This screen identified several potential regulators of EGF degradation, including HRS (used as positive control), PX kinase, MTMR4 and Phafin2/PLEKHF2. As Phafin2 has not previously been shown to be required for EGF receptor (EGFR) degradation, we performed further functional studies on this protein. Loss of Phafin2 was found to decrease early endosome size, whereas overexpression of Phafin2 resulted in enlarged endosomes. Moreover, both the EGFR and the fluid-phase marker dextran were retained in abnormally small endosomes in Phafin2-depleted cells. In yeast two-hybrid analysis we identified Phafin2 as a novel interactor of the endosomal-tethering protein EEA1, and Phafin2 colocalized strongly with EEA1 in microdomains of the endosome membrane. Our results suggest that Phafin2 controls receptor trafficking and fluid-phase transport through early endosomes by facilitating endosome fusion in concert with EEA1.
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Affiliation(s)
- Nina Marie Pedersen
- Department of Biochemistry, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, N-0310, Oslo, Norway
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Lin WJ, Yang CY, Li LL, Yi YH, Chen KW, Lin YC, Liu CC, Lin CH. Lysosomal targeting of phafin1 mediated by Rab7 induces autophagosome formation. Biochem Biophys Res Commun 2012; 417:35-42. [DOI: 10.1016/j.bbrc.2011.11.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 11/09/2011] [Indexed: 12/30/2022]
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12
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Gailite I, Egger-Adam D, Wodarz A. The phosphoinositide-associated protein Rush hour regulates endosomal trafficking in Drosophila. Mol Biol Cell 2011; 23:433-47. [PMID: 22160599 PMCID: PMC3268723 DOI: 10.1091/mbc.e11-02-0154] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Endocytosis regulates multiple cellular processes, including the protein composition of the plasma membrane, intercellular signaling, and cell polarity. We have identified the highly conserved protein Rush hour (Rush) and show that it participates in the regulation of endocytosis. Rush localizes to endosomes via direct binding of its FYVE (Fab1p, YOTB, Vac1p, EEA1) domain to phosphatidylinositol 3-phosphate. Rush also directly binds to Rab GDP dissociation inhibitor (Gdi), which is involved in the activation of Rab proteins. Homozygous rush mutant flies are viable but show genetic interactions with mutations in Gdi, Rab5, hrs, and carnation, the fly homologue of Vps33. Overexpression of Rush disrupts progression of endocytosed cargo and increases late endosome size. Lysosomal marker staining is decreased in Rush-overexpressing cells, pointing to a defect in the transition between late endosomes and lysosomes. Rush also causes formation of endosome clusters, possibly by affecting fusion of endosomes via an interaction with the class C Vps/homotypic fusion and vacuole protein-sorting (HOPS) complex. These results indicate that Rush controls trafficking from early to late endosomes and from late endosomes to lysosomes by modulating the activity of Rab proteins.
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Affiliation(s)
- Ieva Gailite
- Stammzellbiologie, Abteilung Anatomie und Zellbiologie, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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