1
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Valdez S, Robertson M, Qiang Z. Fluorescence Resonance Energy Transfer Measurements in Polymer Science: A Review. Macromol Rapid Commun 2022; 43:e2200421. [PMID: 35689335 DOI: 10.1002/marc.202200421] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 06/06/2022] [Indexed: 12/27/2022]
Abstract
Fluorescence resonance energy transfer (FRET) is a non-invasive characterization method for studying molecular structures and dynamics, providing high spatial resolution at nanometer scale. Over the past decades, FRET-based measurements are developed and widely implemented in synthetic polymer systems for understanding and detecting a variety of nanoscale phenomena, enabling significant advances in polymer science. In this review, the basic principles of fluorescence and FRET are briefly discussed. Several representative research areas are highlighted, where FRET spectroscopy and imaging can be employed to reveal polymer morphology and kinetics. These examples include understanding polymer micelle formation and stability, detecting guest molecule release from polymer host, characterizing supramolecular assembly, imaging composite interfaces, and determining polymer chain conformations and their diffusion kinetics. Finally, a perspective on the opportunities of FRET-based measurements is provided for further allowing their greater contributions in this exciting area.
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Affiliation(s)
- Sara Valdez
- School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Mark Robertson
- School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Zhe Qiang
- School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
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2
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Mesarec L, Drab M, Penič S, Kralj-Iglič V, Iglič A. On the Role of Curved Membrane Nanodomains, and Passive and Active Skeleton Forces in the Determination of Cell Shape and Membrane Budding. Int J Mol Sci 2021; 22:2348. [PMID: 33652934 PMCID: PMC7956631 DOI: 10.3390/ijms22052348] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/18/2021] [Accepted: 02/20/2021] [Indexed: 02/03/2023] Open
Abstract
Biological membranes are composed of isotropic and anisotropic curved nanodomains. Anisotropic membrane components, such as Bin/Amphiphysin/Rvs (BAR) superfamily protein domains, could trigger/facilitate the growth of membrane tubular protrusions, while isotropic curved nanodomains may induce undulated (necklace-like) membrane protrusions. We review the role of isotropic and anisotropic membrane nanodomains in stability of tubular and undulated membrane structures generated or stabilized by cyto- or membrane-skeleton. We also describe the theory of spontaneous self-assembly of isotropic curved membrane nanodomains and derive the critical concentration above which the spontaneous necklace-like membrane protrusion growth is favorable. We show that the actin cytoskeleton growth inside the vesicle or cell can change its equilibrium shape, induce higher degree of segregation of membrane nanodomains or even alter the average orientation angle of anisotropic nanodomains such as BAR domains. These effects may indicate whether the actin cytoskeleton role is only to stabilize membrane protrusions or to generate them by stretching the vesicle membrane. Furthermore, we demonstrate that by taking into account the in-plane orientational ordering of anisotropic membrane nanodomains, direct interactions between them and the extrinsic (deviatoric) curvature elasticity, it is possible to explain the experimentally observed stability of oblate (discocyte) shapes of red blood cells in a broad interval of cell reduced volume. Finally, we present results of numerical calculations and Monte-Carlo simulations which indicate that the active forces of membrane skeleton and cytoskeleton applied to plasma membrane may considerably influence cell shape and membrane budding.
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Affiliation(s)
- Luka Mesarec
- Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (L.M.); (M.D.); (S.P.)
| | - Mitja Drab
- Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (L.M.); (M.D.); (S.P.)
| | - Samo Penič
- Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (L.M.); (M.D.); (S.P.)
| | - Veronika Kralj-Iglič
- Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
- Institute of Biosciences and Bioresources, National Research Council, 80131 Napoli, Italy
| | - Aleš Iglič
- Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (L.M.); (M.D.); (S.P.)
- Institute of Biosciences and Bioresources, National Research Council, 80131 Napoli, Italy
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3
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Chen Y, Zhang W, Chen B, Liu Y, Dong Y, Xu A, Hao Q. Crystal Structure of Human APPL BAR-PH Heterodimer Reveals a Flexible Dimeric BAR curve: Implication in Mutual Regulation of Endosomal Targeting. Biochem J 2020; 477:BCJ20200438. [PMID: 33258922 DOI: 10.1042/bcj20200438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 11/24/2020] [Accepted: 11/30/2020] [Indexed: 11/17/2022]
Abstract
The APPL (adaptor proteins containing pleckstrin homology domain, phosphotyrosine binding domain and a leucine zipper motif) family consists of two isoforms, APPL1 and APPL2. By binding to curved plasma membrane, these adaptor proteins associate with multiple transmembrane receptors and recruit various downstream signaling components. They are involved in the regulation of signaling pathways evoked by a variety of extracellular stimuli, such as adiponectin, insulin, FSH (follicle stimulating hormone), EGF (epidermal growth factor). And they play important roles in cell proliferation, apoptosis, glucose uptake, insulin secretion and sensitivity. However, emerging evidence suggests that APPL1 and APPL2 perform different or even opposite functions and the underlying mechanism remains unclear. As APPL proteins can either homodimerize or heterodimerize in vivo, we hypothesized that heterodimerization of APPL proteins might account for the mechanism. By solving the crystal structure of APPL1-APPL2 BAR-PH heterodimer, we find that the overall structure is crescent-shaped with a longer curvature radius of 76 Å, compared to 55 Å of the APPL1 BAR-PH homodimer. However, there is no significant difference of the curvature between APPL BAR-PH heterodimer and APPL2 homodimer. The data suggest that the APPL1 BAR-PH homodimer, APPL2 BAR-PH homodimer and APPL1/APPL2 BAR-PH heterodimer may bind to endosomes of different sizes. Different positive charge distribution is observed on the concave surface of APPL BAR-PH heterodimer than the homodimers, which may change the affinity of membrane association and subcellular localization. Collectively, APPL2 may regulate APPL1 function through altering the preference of endosome binding by heterodimerization.
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Affiliation(s)
- Yujie Chen
- University of Hong Kong, Hong Kong, China
| | - Wen Zhang
- University of Hong Kong, Hong Kong, China
| | - Bin Chen
- University of Hong Kong, Hong Kong, China
| | - Ying Liu
- Institute of High Energy Physics, CAS, Beijing, China
| | - Yuhui Dong
- Institute of High Energy Physics, CAS, Beijing, China
| | - Aimin Xu
- University of Hong Kong, Hong Kong, China
| | - Quan Hao
- University of Hong Kong, Hong Kong, China
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4
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Guo J, Zhao R, Zhou M, Li J, Yao X, Du J, Chen J, Shen B. TRPP2 and STIM1 form a microdomain to regulate store-operated Ca 2+ entry and blood vessel tone. Cell Commun Signal 2020; 18:138. [PMID: 32867798 PMCID: PMC7457527 DOI: 10.1186/s12964-020-00560-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 03/23/2020] [Indexed: 12/13/2022] Open
Abstract
Background Polycystin-2 (TRPP2) is a Ca2+ permeable nonselective cationic channel essential for maintaining physiological function in live cells. Stromal interaction molecule 1 (STIM1) is an important Ca2+ sensor in store-operated Ca2+ entry (SOCE). Both TRPP2 and STIM1 are expressed in endoplasmic reticular membrane and participate in Ca2+ signaling, suggesting a physical interaction and functional synergism. Methods We performed co-localization, co-immunoprecipitation, and fluorescence resonance energy transfer assay to identify the interactions of TRPP2 and STIM1 in transfected HEK293 cells and native vascular smooth muscle cells (VSMCs). The function of the TRPP2-STIM1 complex in thapsigargin (TG) or adenosine triphosphate (ATP)-induced SOCE was explored using specific small interfering RNA (siRNA). Further, we created TRPP2 conditional knockout (CKO) mouse to investigate the functional role of TRPP2 in agonist-induced vessel contraction. Results TRPP2 and STIM1 form a complex in transfected HEK293 cells and native VSMCs. Genetic manipulations with TRPP2 siRNA, dominant negative TRPP2 or STIM1 siRNA significantly suppressed ATP and TG-induced intracellular Ca2+ release and SOCE in HEK293 cells. Inositol triphosphate receptor inhibitor 2-aminoethyl diphenylborinate (2APB) abolished ATP-induced Ca2+ release and SOCE in HEK293 cells. In addition, TRPP2 and STIM1 knockdown significantly inhibited ATP- and TG-induced STIM1 puncta formation and SOCE in VSMCs. Importantly, knockdown of TRPP2 and STIM1 or conditional knockout TRPP2 markedly suppressed agonist-induced mouse aorta contraction. Conclusions Our data indicate that TRPP2 and STIM1 are physically associated and form a functional complex to regulate agonist-induced intracellular Ca2+ mobilization, SOCE and blood vessel tone. Video abstract
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Affiliation(s)
- Jizheng Guo
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Ren Zhao
- Department of Cardiology, The First Affiliated Hospital of Anhui Medical University, Hefei, 230032, Anhui, China
| | - Muyao Zhou
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Jie Li
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Xiaoqiang Yao
- School of Biomedical Sciences the Chinese University of Hong Kong, Hong Kong, China.,Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Juan Du
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Jiexia Chen
- Department of Geriatrics Cardiology, The First Affiliated Hospital of Anhui Medical University, 218 Jixi Road, Hefei, 230022, Anhui, China.
| | - Bing Shen
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China. .,Anhui Province Key Laboratory of Reproductive Health and Genetics, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China.
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5
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Wang Z, Lu W, Rajapaksha P, Wilkop T, Cai Y, Wei Y. Comparison of in vitro and in vivo oligomeric states of a wild type and mutant trimeric inner membrane multidrug transporter. Biochem Biophys Rep 2018; 16:122-129. [PMID: 30417130 PMCID: PMC6216019 DOI: 10.1016/j.bbrep.2018.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Many membrane proteins exist and function as oligomers or protein complexes. Routine analytical methods involve extraction and solubilization of the proteins with detergents, which could disturb their actual oligomeric state. AcrB is a trimeric inner membrane multidrug transporter in E. coli. In previous studies, we created a mutant AcrBP223G, which behaves like a monomer when extracted from the cell membrane. However, the actual oligomeric state of AcrBP223G in cell membranes remained unclear, which complicated the interpretation of the mechanism by which the mutation affects function. Here we used several complementary methods to determine the oligomeric state of AcrBP223G in E. coli cell membranes. Two sets of quantitative fluorescent techniques were exploited. For these, we created fluorescent tagged AcrB, AcrB-CFP and AcrB-YPet. Fluorescence resonance energy transfer (FRET) and fluorescence recovery after photobleaching (FRAP) were employed to characterize independently the efficiency of energy transfer between co-expressed AcrB-CFP and AcrB-YPet, and the diffusion coefficient of AcrB-YPet and AcrBP223G-YPet in live E. coli cells. Second, we introduced Cys pairs at the inter-subunit interface and used controlled oxidation to probe inter-subunit distances. The results from all studies converge on the conclusion that AcrBP223G exists as a trimer in cell membranes, which dissociates during the purification steps. The small change in trimer affinity and structure leads to a significant loss of AcrB activity. In addition, throughout this study we developed protocols and established benchmark values, useful for further studies on membrane protein associations in cell membranes.
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Affiliation(s)
- Zhaoshuai Wang
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, United States
| | - Wei Lu
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, United States
| | - Prasangi Rajapaksha
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, United States
| | - Thomas Wilkop
- Light Microscopy Core, University of Kentucky, Lexington, KY 40536, United States
| | - Yuguang Cai
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, United States
| | - Yinan Wei
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, United States
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Diggins NL, Kang H, Weaver A, Webb DJ. α5β1 integrin trafficking and Rac activation are regulated by APPL1 in a Rab5-dependent manner to inhibit cell migration. J Cell Sci 2018; 131:jcs.207019. [PMID: 29361527 DOI: 10.1242/jcs.207019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 01/09/2018] [Indexed: 01/04/2023] Open
Abstract
Cell migration is a tightly coordinated process that requires the spatiotemporal regulation of many molecular components. Because adaptor proteins can serve as integrators of cellular events, they are being increasingly studied as regulators of cell migration. The adaptor protein containing a pleckstrin-homology (PH) domain, phosphotyrosine binding (PTB) domain, and leucine zipper motif 1 (APPL1) is a 709 amino acid endosomal protein that plays a role in cell proliferation and survival as well as endosomal trafficking and signaling. However, its function in regulating cell migration is poorly understood. Here, we show that APPL1 hinders cell migration by modulating both trafficking and signaling events controlled by Rab5 in cancer cells. APPL1 decreases internalization and increases recycling of α5β1 integrin, leading to higher levels of α5β1 integrin at the cell surface that hinder adhesion dynamics. Furthermore, APPL1 decreases the activity of the GTPase Rac and its effector PAK, which in turn regulate cell migration. Thus, we demonstrate a novel role for the interaction between APPL1 and Rab5 in governing crosstalk between signaling and trafficking pathways on endosomes to affect cancer cell migration.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Nicole L Diggins
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Hakmook Kang
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Alissa Weaver
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.,Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Donna J Webb
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA.,Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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7
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Morais GP, Vicente LGD, Oliveira LDC, Pinto AP, Rocha ALD, Pereira BC, Pauli JR, Silva ASRD. Nonfunctional overreaching and hepatic adaptations of APPL1 and APPL2. MOTRIZ: REVISTA DE EDUCACAO FISICA 2017. [DOI: 10.1590/s1980-6574201700si0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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8
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Screening and identification of proteins interacting with IL-24 by the yeast two-hybrid screen, Co-IP, and FRET assays. Anticancer Drugs 2016; 27:318-27. [PMID: 26930462 DOI: 10.1097/cad.0000000000000343] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Interleukin-24 (IL-24) is an ideal tumor-suppressor gene, but the mechanisms underlying its antitumor specificity remain to be elucidated. The best way to investigate these problems is to begin from the initiation of corresponding signaling cascades activated by IL-24 with screening and identifying those proteins that interacted with IL-24. With the aim of identifying these initial interactions, a yeast two-hybrid screening was performed by transforming AH109 cells containing PGBKT7-IL-24 with a liver cDNA plasmid library. These cells were then plated on synthetic nutrient medium (SD/-Trp/-Leu/-His) for the first screening and on quadruple dropout medium containing X-α-gal for the second screening. Positive colonies were further verified by repeating the MATE experiments, co-immunoprecipitation (Co-IP) analysis, and fluorescence resonance energy transfer (FRET) assays in vitro. Following the yeast two-hybrid screening, 15 genes were selected for sequencing, with two genes, HLA-C and NDUFA13, further verified using Co-IP assays and FRET assays. Both HLA-C and NDUFA13 were found to interact with IL-24. We found that HLA-C and NDUFA13 could interact with IL-24 and it may be involved in the signal induced by IL-24. Overall, this study contributes further insight into the cancer-specific apoptosis-inducing abilities of IL-24 to potentially enhance its therapeutic potential, and it also provides outlets for other biological functions of IL-24.
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9
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Yeo JC, Wall AA, Luo L, Condon ND, Stow JL. Distinct Roles for APPL1 and APPL2 in Regulating Toll-like Receptor 4 Signaling in Macrophages. Traffic 2016; 17:1014-26. [PMID: 27219021 DOI: 10.1111/tra.12415] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 05/09/2016] [Accepted: 05/09/2016] [Indexed: 12/17/2022]
Abstract
Macrophages are activated by contact with pathogens to mount innate immune defenses against infection. Toll-like receptor 4 (TLR4) at the macrophage surface recognizes and binds bacterial lipopolysaccharide (LPS), setting off signaling and transcriptional events that lead to the secretion of pro- and anti-inflammatory cytokines; these in turn control inflammatory and antimicrobial responses. Although the complex regulatory pathways downstream of TLR4 have been extensively studied, further molecules critical for modulating the resulting cytokine outputs remain to be characterized. Here we establish potential roles for APPL1 and 2 signaling adaptors as regulators of LPS/TLR4-induced signaling, transcription, and cytokine secretion. APPL1 and 2 are differentially localized to distinct signaling-competent membrane domains on the surface and in endocytic compartments of LPS-activated macrophages. By depleting cells of each adaptor respectively we show separate and opposing functions for APPL1 and 2 in Akt and MAPK signaling. Specifically, APPL2 has a dominant role in nuclear translocation of NF-KB p65 and it serves to constrain the secretion of pro- and anti-inflammatory cytokines. The APPLs, and in particular APPL2, are thus revealed as adaptors with important capacity to modulate inflammatory responses mounted by LPS/TLR4 during infection.
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Affiliation(s)
- Jeremy C Yeo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Adam A Wall
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Lin Luo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
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10
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Mesarec L, Góźdź W, Iglič VK, Kralj S, Iglič A. Closed membrane shapes with attached BAR domains subject to external force of actin filaments. Colloids Surf B Biointerfaces 2016; 141:132-140. [PMID: 26854580 DOI: 10.1016/j.colsurfb.2016.01.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/02/2016] [Accepted: 01/05/2016] [Indexed: 10/22/2022]
Abstract
Membrane deformations induced by attached BAR superfamily domains could trigger or facilitate the growth of plasma membrane protrusions. The BAR domain family consists of BAR, F-BAR and I-BAR domains, each enforcing a different local curvature when attached to the membrane surface. Our theoretical study mainly focuses on the role of I-BAR in the membrane tubular deformations generated or stabilised by actin filaments. The influence of the area density of membrane attached BAR domains and their intrinsic curvature on the closed membrane shapes (vesicles) was investigated numerically. We derived an analytical approximative expression for the critical relative area density of BARs at which the membrane tubular protrusions on vesicles are most prominent. We have shown that the BARs with a higher intrinsic curvature induce thinner and longer cylindrical protrusions. The average orientation of the membrane attached BARs is altered when the vesicle shape is subjected to external force of growing actin rod-like structure inside a vesicle. The average orientation angle of membrane attached BARs may indicate whether the actin filaments are just stabilising the protrusion or generating it by stretching the vesicle.
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Affiliation(s)
- Luka Mesarec
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia.
| | - Wojciech Góźdź
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Veronika Kralj Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia; Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Zdravstvena 5, SI-1000 Ljubljana, Slovenia
| | - Samo Kralj
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, SI-2000 Maribor, Slovenia; Jožef Stefan Institute, P.O. Box 3000, SI-1000 Ljubljana, Slovenia
| | - Aleš Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia; Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Zdravstvena 5, SI-1000 Ljubljana, Slovenia
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11
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Prudente S, Jungtrakoon P, Marucci A, Ludovico O, Buranasupkajorn P, Mazza T, Hastings T, Milano T, Morini E, Mercuri L, Bailetti D, Mendonca C, Alberico F, Basile G, Romani M, Miccinilli E, Pizzuti A, Carella M, Barbetti F, Pascarella S, Marchetti P, Trischitta V, Di Paola R, Doria A. Loss-of-Function Mutations in APPL1 in Familial Diabetes Mellitus. Am J Hum Genet 2015; 97:177-85. [PMID: 26073777 DOI: 10.1016/j.ajhg.2015.05.011] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/14/2015] [Indexed: 12/29/2022] Open
Abstract
Diabetes mellitus is a highly heterogeneous disorder encompassing several distinct forms with different clinical manifestations including a wide spectrum of age at onset. Despite many advances, the causal genetic defect remains unknown for many subtypes of the disease, including some of those forms with an apparent Mendelian mode of inheritance. Here we report two loss-of-function mutations (c.1655T>A [p.Leu552(∗)] and c.280G>A [p.Asp94Asn]) in the gene for the Adaptor Protein, Phosphotyrosine Interaction, PH domain, and leucine zipper containing 1 (APPL1) that were identified by means of whole-exome sequencing in two large families with a high prevalence of diabetes not due to mutations in known genes involved in maturity onset diabetes of the young (MODY). APPL1 binds to AKT2, a key molecule in the insulin signaling pathway, thereby enhancing insulin-induced AKT2 activation and downstream signaling leading to insulin action and secretion. Both mutations cause APPL1 loss of function. The p.Leu552(∗) alteration totally abolishes APPL1 protein expression in HepG2 transfected cells and the p.Asp94Asn alteration causes significant reduction in the enhancement of the insulin-stimulated AKT2 and GSK3β phosphorylation that is observed after wild-type APPL1 transfection. These findings-linking APPL1 mutations to familial forms of diabetes-reaffirm the critical role of APPL1 in glucose homeostasis.
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Affiliation(s)
- Sabrina Prudente
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
| | - Prapaporn Jungtrakoon
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Antonella Marucci
- Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Ornella Ludovico
- Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Patinut Buranasupkajorn
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Tommaso Mazza
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Timothy Hastings
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
| | - Teresa Milano
- Department of Biochemical Sciences, Sapienza University, 00185 Rome, Italy
| | - Eleonora Morini
- Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Luana Mercuri
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Diego Bailetti
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy
| | | | - Federica Alberico
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Giorgio Basile
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy
| | - Marta Romani
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Elide Miccinilli
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Antonio Pizzuti
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy
| | - Massimo Carella
- Unit of Medical Genetics, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Fabrizio Barbetti
- Laboratory of Mendelian Diabetes, Bambino Gesù Childrens' Hospital, 00165 Rome, Italy; Department of Experimental Medicine and Surgery, University of Tor Vergata, 00133 Rome, Italy
| | - Stefano Pascarella
- Department of Biochemical Sciences, Sapienza University, 00185 Rome, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, University of Pisa, 56127 Pisa, Italy
| | - Vincenzo Trischitta
- Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy
| | - Rosa Di Paola
- Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Alessandro Doria
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
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Yeo JC, Wall AA, Luo L, Stow JL. Rab31 and APPL2 enhance FcγR-mediated phagocytosis through PI3K/Akt signaling in macrophages. Mol Biol Cell 2015; 26:952-65. [PMID: 25568335 PMCID: PMC4342030 DOI: 10.1091/mbc.e14-10-1457] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Rab31 recruits APPL2 to regulate phagocytic cup closure and FcγR signaling pathways via production of PI(3,4,5)P3 in macrophages. APPL2 is poised to activate macrophages and act as a counterpoint to APPL1 in FcγR-mediated PI3K/Akt signaling. New locations and roles are found for Rab31 and APPL2 by which they contribute to innate immune functions. Membrane remodeling in the early stages of phagocytosis enables the engulfment of particles or pathogens and receptor signaling to activate innate immune responses. Members of the Rab GTPase family and their disparate effectors are recruited sequentially to regulate steps throughout phagocytosis. Rab31 (Rab22b) is known for regulating post-Golgi trafficking, and here we show in macrophages that Rab31-GTP is additionally and specifically recruited to early-stage phagosomes. At phagocytic cups, Rab31 is first recruited during the phosphoinositide transition from PI(4,5)P2 to PI(3,4,5)P3, and it persists on PI(3)P-enriched phagosomes. During early phagocytosis, we find that Rab31 recruits the signaling adaptor APPL2. siRNA depletion of either Rab31 or APPL2 reduces FcγR-mediated phagocytosis. Mechanistically, this corresponds with a delay in the transition to PI(3,4,5)P3 and phagocytic cup closure. APPL2 depletion also reduced PI3K/Akt signaling and enhanced p38 signaling from FcγR. We thus conclude that Rab31/APPL2 is required for key roles in phagocytosis and prosurvival responses of macrophages. Of interest, in terms of localization and function, this Rab31/APPL2 complex is distinct from the Rab5/APPL1 complex, which is also involved in phagocytosis and signaling.
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Affiliation(s)
- Jeremy C Yeo
- Institute for Molecular Bioscience, University of Queensland, Brisbane QLD 4072, Australia
| | - Adam A Wall
- Institute for Molecular Bioscience, University of Queensland, Brisbane QLD 4072, Australia
| | - Lin Luo
- Institute for Molecular Bioscience, University of Queensland, Brisbane QLD 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience, University of Queensland, Brisbane QLD 4072, Australia
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Cheng KKY, Lam KSL, Wang B, Xu A. Signaling mechanisms underlying the insulin-sensitizing effects of adiponectin. Best Pract Res Clin Endocrinol Metab 2014; 28:3-13. [PMID: 24417941 DOI: 10.1016/j.beem.2013.06.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adiponectin is an insulin-sensitizing adipokine with protective effects against a cluster of obesity-related metabolic and cardiovascular disorders. The adipokine exerts its insulin-sensitizing effects by alleviation of obesity-induced ectopic lipid accumulation, lipotoxicity and chronic inflammation, as well as by direct cross-talk with insulin signaling cascades. Adiponectin and insulin signaling pathways converge at the adaptor protein APPL1. On the one hand, APPL1 interacts with adiponectin receptors and mediates both metabolic and vascular actions of adiponectin through activation of AMP-activated protein kinase and p38 MAP kinase. On the other hand, APPL1 potentiates both the actions and secretion of insulin by fine-tuning the Akt activity in multiple insulin target tissues. In obese animals, reduced APPL1 expression contributes to both insulin resistance and defective insulin secretion. This review summarizes recent advances on the molecular mechanisms by which adiponectin sensitizes insulin actions, and discusses the roles of APPL1 in regulating both adiponectin and insulin signaling cascades.
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Affiliation(s)
- Kenneth K Y Cheng
- Department of Medicine, The University of Hong Kong, Hong Kong; Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Hong Kong
| | - Karen S L Lam
- Department of Medicine, The University of Hong Kong, Hong Kong; Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Hong Kong
| | - Baile Wang
- Department of Medicine, The University of Hong Kong, Hong Kong
| | - Aimin Xu
- Department of Medicine, The University of Hong Kong, Hong Kong; Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Hong Kong; Department of Pharmacology & Pharmacy, The University of Hong Kong, Hong Kong.
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14
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Rashid S, Parveen Z, Ferdous S, Bibi N. Mutually exclusive binding of APPL(PH) to BAR domain and Reptin regulates β-catenin dependent transcriptional events. Comput Biol Chem 2013; 47:48-55. [PMID: 23891720 DOI: 10.1016/j.compbiolchem.2013.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 05/29/2013] [Accepted: 05/30/2013] [Indexed: 12/20/2022]
Abstract
Reptin functions in a wide range of biological processes including chromatin remodelling, nucleolar organization and transcriptional regulation of WNT signalling. As β-catenin dependent transcriptional repression and activation events involve binding of Reptin and histone deacetylase 1 to APPL endocytic proteins, this complex has become an important target to identify molecules governing endocytic processes and WNT signalling. Here, we describe the structural basis of APPL binding to Reptin to explore their mode of binding in context with APPL1/APPL2 dimerization. There is an evidence that both PH and BAR domains of APPL proteins exhibit alternately conserved regions involved in hetero-dimerization process and our in-silico data also corroborate this fact. Moreover, APPL2(PH) domain binds to the BAR domain region encompassing a nuclear localization signal. We conclude that APPL(PH) binding to BAR domain and Reptin is mutually exclusive which regulates the nucleocytoplasmic shuttling of Reptin. Furthermore, Reptin is unable to bind with membrane-associated APPL proteins. These observations were further expanded by experimental approaches where we identified a novel point mutation D316N lying in the APPL1(PH) domain which resulted in a significantly reduced binding with Reptin. By luciferase assays, we observed that overexpression of APPL1(D316N) and APPL1(WT) stimulated β-catenin/TCF dependent transcriptional activity in a similar manner which suggested that binding of Reptin to APPL1 is not necessary for β-catenin dependent target gene expression. Overall, our data attempt to highlight a comparative role of APPL proteins in controlling β-catenin dependent transcription mechanism which may improve our understanding of gene regulation.
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Affiliation(s)
- Sajid Rashid
- National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan.
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Broussard JA, Lin WH, Majumdar D, Anderson B, Eason B, Brown CM, Webb DJ. The endosomal adaptor protein APPL1 impairs the turnover of leading edge adhesions to regulate cell migration. Mol Biol Cell 2012; 23:1486-99. [PMID: 22379109 PMCID: PMC3327316 DOI: 10.1091/mbc.e11-02-0124] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cell migration is a complex process that requires the integration of signaling events that occur in distinct locations within the cell. Adaptor proteins, which can localize to different subcellular compartments, where they bring together key signaling proteins, are emerging as attractive candidates for controlling spatially coordinated processes. However, their function in regulating cell migration is not well understood. In this study, we demonstrate a novel role for the adaptor protein containing a pleckstrin-homology (PH) domain, phosphotyrosine-binding (PTB) domain, and leucine zipper motif 1 (APPL1) in regulating cell migration. APPL1 impairs migration by hindering the turnover of adhesions at the leading edge of cells. The mechanism by which APPL1 regulates migration and adhesion dynamics is by inhibiting the activity of the serine/threonine kinase Akt at the cell edge and within adhesions. In addition, APPL1 significantly decreases the tyrosine phosphorylation of Akt by the nonreceptor tyrosine kinase Src, which is critical for Akt-mediated cell migration. Thus, our results demonstrate an important new function for APPL1 in regulating cell migration and adhesion turnover through a mechanism that depends on Src and Akt. Moreover, our data further underscore the importance of adaptor proteins in modulating the flow of information through signaling pathways.
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Affiliation(s)
- Joshua A Broussard
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Nashville, TN 37235, USA
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Urbanska A, Sadowski L, Kalaidzidis Y, Miaczynska M. Biochemical characterization of APPL endosomes: the role of annexin A2 in APPL membrane recruitment. Traffic 2011; 12:1227-41. [PMID: 21645192 PMCID: PMC3380557 DOI: 10.1111/j.1600-0854.2011.01226.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
APPL endosomes are a recently identified subpopulation of early endosomes characterized by the presence of two homologous Rab5 effector proteins APPL1 and APPL2. They exhibit only limited colocalization with EEA1, another Rab5 effector and a marker of the canonical early endosomes. Although APPL endosomes appear to play important roles in cargo trafficking and signal transduction, their protein composition and biochemical properties remain largely unknown. Here we employed membrane fractionation methods to characterize APPL endosomes biochemically. We demonstrate that they represent heterogeneous membrane structures which can be discriminated from the canonical EEA1-positive early endosomes by their partly different physical properties and a distinct migration pattern in the continuous density gradients. In search for other potential markers of APPL endosomes we identified Annexin A2 as an interacting partner of both APPL1 and APPL2. Annexin A2 is a Ca2+ and phosphatidylinositol 4,5-bisphosphate binding protein, previously implicated in several endocytic steps. We show that Annexin A2 co-fractionates and colocalizes with APPL endosomes. Moreover, silencing of its expression causes solubilization of APPL2 from endosomes. Although Annexin A2 is not an exclusive marker of APPL endosomes, our data suggest that it has an important function in membrane recruitment of APPL proteins, acting in parallel to Rab5.
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Affiliation(s)
- Anna Urbanska
- International Institute of Molecular and Cell Biology, Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland
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