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Lahree A, Baptista SDJS, Marques S, Perschin V, Zuzarte-Luís V, Goel M, Choudhary HH, Mishra S, Stigloher C, Zerial M, Sundaramurthy V, Mota MM. Active APPL1 sequestration by Plasmodium favors liver-stage development. Cell Rep 2022; 39:110886. [PMID: 35649358 DOI: 10.1016/j.celrep.2022.110886] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/10/2022] [Accepted: 05/06/2022] [Indexed: 11/03/2022] Open
Abstract
Intracellular pathogens manipulate host cells to survive and thrive. Cellular sensing and signaling pathways are among the key host machineries deregulated to favor infection. In this study, we show that liver-stage Plasmodium parasites compete with the host to sequester a host endosomal-adaptor protein (APPL1) known to regulate signaling in response to endocytosis. The enrichment of APPL1 at the parasitophorous vacuole membrane (PVM) involves an atypical Plasmodium Rab5 isoform (Rab5b). Depletion of host APPL1 alters neither the infection nor parasite development; however, upon overexpression of a GTPase-deficient host Rab5 mutant (hRab5_Q79L), the parasites are smaller and their PVM is stripped of APPL1. Infection with the GTPase-deficient Plasmodium berghei Rab5b mutant (PbRab5b_Q91L) in this case rescues the PVM APPL1 signal and parasite size. In summary, we observe a robust correlation between the level of APPL1 retention at the PVM and parasite size during exoerythrocytic development.
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Affiliation(s)
- Aparajita Lahree
- Instituto de Medicina Molecular- João Lobo Antunes (iMM-JLA), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal; Departamento de Bioengenharia, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Sara de Jesus Santos Baptista
- Instituto de Medicina Molecular- João Lobo Antunes (iMM-JLA), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Sofia Marques
- Instituto de Medicina Molecular- João Lobo Antunes (iMM-JLA), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Veronika Perschin
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Vanessa Zuzarte-Luís
- Instituto de Medicina Molecular- João Lobo Antunes (iMM-JLA), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Manisha Goel
- National Centre for Biological Sciences, Tata Institute of Fundamental Research (NCBS), Bellary Road, Bangalore 560065, Karnataka, India
| | - Hadi Hasan Choudhary
- CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, Uttar Pradesh, India
| | - Satish Mishra
- CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, Uttar Pradesh, India
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Marino Zerial
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Varadharajan Sundaramurthy
- National Centre for Biological Sciences, Tata Institute of Fundamental Research (NCBS), Bellary Road, Bangalore 560065, Karnataka, India
| | - Maria M Mota
- Instituto de Medicina Molecular- João Lobo Antunes (iMM-JLA), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal.
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2
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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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3
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The adaptor protein APPL2 controls glucose-stimulated insulin secretion via F-actin remodeling in pancreatic β-cells. Proc Natl Acad Sci U S A 2020; 117:28307-28315. [PMID: 33122440 DOI: 10.1073/pnas.2016997117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Filamentous actin (F-actin) cytoskeletal remodeling is critical for glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells, and its dysregulation causes type 2 diabetes. The adaptor protein APPL1 promotes first-phase GSIS by up-regulating soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein expression. However, whether APPL2 (a close homology of APPL1 with the same domain organization) plays a role in β-cell functions is unknown. Here, we show that APPL2 enhances GSIS by promoting F-actin remodeling via the small GTPase Rac1 in pancreatic β-cells. β-cell specific abrogation of APPL2 impaired GSIS, leading to glucose intolerance in mice. APPL2 deficiency largely abolished glucose-induced first- and second-phase insulin secretion in pancreatic islets. Real-time live-cell imaging and phalloidin staining revealed that APPL2 deficiency abolished glucose-induced F-actin depolymerization in pancreatic islets. Likewise, knockdown of APPL2 expression impaired glucose-stimulated F-actin depolymerization and subsequent insulin secretion in INS-1E cells, which were attributable to the impairment of Ras-related C3 botulinum toxin substrate 1 (Rac1) activation. Treatment with the F-actin depolymerization chemical compounds or overexpression of gelsolin (a F-actin remodeling protein) rescued APPL2 deficiency-induced defective GSIS. In addition, APPL2 interacted with Rac GTPase activating protein 1 (RacGAP1) in a glucose-dependent manner via the bin/amphiphysin/rvs-pleckstrin homology (BAR-PH) domain of APPL2 in INS-1E cells and HEK293 cells. Concomitant knockdown of RacGAP1 expression reverted APPL2 deficiency-induced defective GSIS, F-actin remodeling, and Rac1 activation in INS-1E cells. Our data indicate that APPL2 interacts with RacGAP1 and suppresses its negative action on Rac1 activity and F-actin depolymerization thereby enhancing GSIS in pancreatic β-cells.
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4
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Galan-Davila AK, Ryu J, Dong K, Xiao Y, Dai Z, Zhang D, Li Z, Dick AM, Liu KD, Kamat A, Lu M, Dong Q, Liu F, Dong LQ. Alternative splicing variant of the scaffold protein APPL1 suppresses hepatic adiponectin signaling and function. J Biol Chem 2018; 293:6064-6074. [PMID: 29483192 DOI: 10.1074/jbc.ra118.002162] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/09/2018] [Indexed: 11/06/2022] Open
Abstract
Adiponectin is an adipocyte-derived hormone with antidiabetic activities that include increasing the sensitivity of cells to insulin. Adaptor protein containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif (APPL1) stimulates adiponectin signaling and promotes adiponectin's insulin-sensitizing effects by binding to two adiponectin receptors, AdipoR1 and AdipoR2, and the insulin receptor. In this study, we report an alternative splicing variant of APPL1 (APPL1sv) that is highly expressed in mouse liver, pancreas, and spleen tissues. The expression levels of APPL1sv in liver tissues were enhanced in a mouse model of obesity and diabetic dyslipidemia (i.e. db/db mice) and reduced in calorie-restricted mice compared with ad libitum-fed mice. APPL1sv overexpression or suppression inhibited or enhanced, respectively, adiponectin-stimulated phosphorylation of AMP protein kinase (AMPK) in mouse hepatocytes. We also found that APPL1sv binds to AdipoR1 and AdipoR2 under basal conditions and that adiponectin treatment reduces this binding. Overexpression of APPL1sv blocked adiponectin-induced interactions of APPL1 with the adiponectin receptors. Moreover, adenovirus-mediated and short hairpin RNA-based suppression of APPL1sv greatly reduced high fat diet-induced insulin resistance and hepatic glucose production in mice. Our study identifies a key suppressor of hepatic adiponectin signaling and insulin sensitivity, a finding that may shed light on identifying effective therapeutic targets for treating insulin resistance and type 2 diabetes.
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Affiliation(s)
- Amanda K Galan-Davila
- From the Departments of Cell Systems and Anatomy.,the Department of Clinical and Applied Science Education, University of the Incarnate Word School of Osteopathic Medicine, San Antonio, Texas 78253
| | - Jiyoon Ryu
- From the Departments of Cell Systems and Anatomy
| | - Kun Dong
- From the Departments of Cell Systems and Anatomy
| | - Yang Xiao
- From the Departments of Cell Systems and Anatomy
| | - Zhe Dai
- From the Departments of Cell Systems and Anatomy
| | - Deling Zhang
- From the Departments of Cell Systems and Anatomy
| | - Zhi Li
- From the Departments of Cell Systems and Anatomy
| | | | - Kevin D Liu
- From the Departments of Cell Systems and Anatomy
| | - Amrita Kamat
- Medicine and.,The Barshop Center for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, Texas 78229-3900.,the Geriatric Research Education and Clinical Center (GRECC), South Texas Veterans Health Care System, San Antonio, Texas 78229
| | - Min Lu
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093.,the Merck Research Laboratory, Diabetes Early Discovery, Boston, Massachusetts 02115-5727
| | - Qunfeng Dong
- the Center for Biomedical Informatics, Department of Public Health Sciences, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois 60153, and
| | - Feng Liu
- The Barshop Center for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, Texas 78229-3900.,Pharmacology, and
| | - Lily Q Dong
- From the Departments of Cell Systems and Anatomy, .,The Barshop Center for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, Texas 78229-3900
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5
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APPL1 is a multifunctional endosomal signaling adaptor protein. Biochem Soc Trans 2017; 45:771-779. [PMID: 28620038 DOI: 10.1042/bst20160191] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/17/2017] [Accepted: 03/22/2017] [Indexed: 11/17/2022]
Abstract
Endosomal adaptor proteins are important regulators of signaling pathways underlying many biological processes. These adaptors can integrate signals from multiple pathways via localization to specific endosomal compartments, as well as through multiple protein-protein interactions. One such adaptor protein that has been implicated in regulating signaling pathways is the adaptor protein containing a pleckstrin homology (PH) domain, phosphotyrosine-binding (PTB) domain, and leucine zipper motif 1 (APPL1). APPL1 localizes to a subset of Rab5-positive endosomes through its Bin-Amphiphysin-Rvs and PH domains, and it coordinates signaling pathways through its interaction with many signaling receptors and proteins through its PTB domain. This review discusses our current understanding of the role of APPL1 in signaling and trafficking, as well as highlights recent work into the function of APPL1 in cell migration and adhesion.
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6
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Salzer U, Kostan J, Djinović-Carugo K. Deciphering the BAR code of membrane modulators. Cell Mol Life Sci 2017; 74:2413-2438. [PMID: 28243699 PMCID: PMC5487894 DOI: 10.1007/s00018-017-2478-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/25/2017] [Accepted: 01/27/2017] [Indexed: 01/06/2023]
Abstract
The BAR domain is the eponymous domain of the “BAR-domain protein superfamily”, a large and diverse set of mostly multi-domain proteins that play eminent roles at the membrane cytoskeleton interface. BAR domain homodimers are the functional units that peripherally associate with lipid membranes and are involved in membrane sculpting activities. Differences in their intrinsic curvatures and lipid-binding properties account for a large variety in membrane modulating properties. Membrane activities of BAR domains are further modified and regulated by intramolecular or inter-subunit domains, by intermolecular protein interactions, and by posttranslational modifications. Rather than providing detailed cell biological information on single members of this superfamily, this review focuses on biochemical, biophysical, and structural aspects and on recent findings that paradigmatically promote our understanding of processes driven and modulated by BAR domains.
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Affiliation(s)
- Ulrich Salzer
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - Julius Kostan
- Max F. Perutz Laboratories, Department of Structural and Computational Biology, University of Vienna, Campus Vienna Biocenter 5, 1030, Vienna, Austria
| | - Kristina Djinović-Carugo
- Max F. Perutz Laboratories, Department of Structural and Computational Biology, University of Vienna, Campus Vienna Biocenter 5, 1030, Vienna, Austria.
- Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 119, 1000, Ljubljana, Slovenia.
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7
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Liu Z, Xiao T, Peng X, Li G, Hu F. APPLs: More than just adiponectin receptor binding proteins. Cell Signal 2017; 32:76-84. [PMID: 28108259 DOI: 10.1016/j.cellsig.2017.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 12/31/2022]
Abstract
APPLs (adaptor proteins containing the pleckstrin homology domain, phosphotyrosine binding domain and leucine zipper motif) are multifunctional adaptor proteins that bind to various membrane receptors, nuclear factors and signaling proteins to regulate many biological activities and processes, such as cell proliferation, chromatin remodeling, endosomal trafficking, cell survival, cell metabolism and apoptosis. APPL1, one of the APPL isoforms, was the first identified protein and interacts directly with adiponectin receptors to mediate adiponectin signaling to enhance lipid oxidation and glucose uptake. APPLs also act on insulin signaling pathways and are important mediators of insulin sensitization. Based on recent findings, this review highlights the critical roles of APPLs, particularly APPL1 and its isoform partner APPL2, in mediating adiponectin, insulin, endosomal trafficking and other signaling pathways. A deep understanding of APPLs and their related signaling pathways may potentially lead to therapeutic and interventional treatments for obesity, diabetes, cancer and neurodegenerative diseases.
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Affiliation(s)
- Zhuoying Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Ting Xiao
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Xiaoyu Peng
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China.
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8
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Chua CEL, Tang BL. Role of Rab GTPases and their interacting proteins in mediating metabolic signalling and regulation. Cell Mol Life Sci 2015; 72:2289-304. [PMID: 25690707 PMCID: PMC11113524 DOI: 10.1007/s00018-015-1862-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 10/24/2022]
Abstract
The vesicular transport pathways, which shuttle materials to and from the cell surface and within the cell, and the metabolic (growth factor and nutrient) signalling pathways, which integrate a variety of extracellular and intracellular signals to mediate growth, proliferation or survival, are both important for cellular physiology. There is evidence to suggest that the transport and metabolic signalling pathways intersect-vesicular transport can affect the regulation of metabolic signals and vice versa. The Rab family GTPases regulate the specificity of vesicular transport steps in the cell. Together with their interacting proteins, Rabs would likely constitute the points of intersection between vesicular transport and metabolic signalling pathways. Examples of these points would include growth factor signalling, glucose and lipid metabolism, as well as autophagy. Many of these processes involve mechanistic/mammalian target of rapamycin (mTOR) complex 1 (mTORC1) in downstream cascades, or are regulated by TORC signalling. A general functionality of the vesicular transport processes controlled by the Rabs is also important for spatial and temporal regulation of the transmission of metabolic signals between the cell surface and the nucleus. In other cases, specific Rabs and their interacting proteins are known to function in recruiting metabolism-related proteins to target membranes, or may compete with other factors in the TORC signalling pathway as a means of metabolic regulation. We review and discuss herein examples of how Rabs and their interacting proteins can mediate metabolic signalling and regulation in cells.
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Affiliation(s)
- Christelle En Lin Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University Health System, 8 Medical Drive, Singapore, 117597, Singapore,
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9
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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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10
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Chua CEL, Tang BL. The role of the small GTPase Rab31 in cancer. J Cell Mol Med 2014; 19:1-10. [PMID: 25472813 PMCID: PMC4288343 DOI: 10.1111/jcmm.12403] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 07/18/2014] [Indexed: 12/28/2022] Open
Abstract
Members of the small GTPase family Rab are emerging as potentially important factors in cancer development and progression. A good number of Rabs have been implicated or associated with various human cancers, and much recent excitement has been associated with the roles of the Rab11 subfamily member Rab25 and its effector, the Rab coupling protein (RCP), in tumourigenesis and metastasis. In this review, we focus on a Rab5 subfamily member, Rab31, and its implicated role in cancer. Well recognized as a breast cancer marker with good prognostic value, recent findings have provided some insights as to the mechanism underlying Rab31's influence on oncogenesis. Levels of Oestrogen Receptor α (ERα)- responsive Rab31 could be elevated through stabilization of its transcript by the RNA binding protein HuR, or though activation by the oncoprotein mucin1-C (MUC1-C), which forms a transcriptional complex with ERα. Elevated Rab31 stabilizes MUC1-C levels in an auto-inductive loop that could lead to aberrant signalling and gene expression associated with cancer progression. Rab31 and its guanine nucleotide exchange factor GAPex-5 have, however, also been shown to enhance early endosome-late endosome transport and degradation of the epidermal growth factor receptor (EGFR). The multifaceted action and influences of Rab31 in cancer is discussed in the light of its new interacting partners and pathways.
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Affiliation(s)
- Christelle En Lin Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
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11
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Cheng KKY, Zhu W, Chen B, Wang Y, Wu D, Sweeney G, Wang B, Lam KSL, Xu A. The adaptor protein APPL2 inhibits insulin-stimulated glucose uptake by interacting with TBC1D1 in skeletal muscle. Diabetes 2014; 63:3748-58. [PMID: 24879834 DOI: 10.2337/db14-0337] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Insulin stimulates glucose uptake by promoting the trafficking of GLUT4 to the plasma membrane in muscle cells, and impairment of this insulin action contributes to hyperglycemia in type 2 diabetes. The adaptor protein APPL1 potentiates insulin-stimulated Akt activation and downstream actions. However, the physiological functions of APPL2, a close homolog of APPL1, in regulating glucose metabolism remain elusive. We show that insulin-evoked plasma membrane recruitment of GLUT4 and glucose uptake are impaired by APPL2 overexpression but enhanced by APPL2 knockdown. Likewise, conditional deletion of APPL2 in skeletal muscles enhances insulin sensitivity, leading to an improvement in glucose tolerance. We identified the Rab-GTPase-activating protein TBC1D1 as an interacting partner of APPL2. Insulin stimulates TBC1D1 phosphorylation on serine 235, leading to enhanced interaction with the BAR domain of APPL2, which in turn suppresses insulin-evoked TBC1D1 phosphorylation on threonine 596 in cultured myotubes and skeletal muscle. Substitution of serine 235 with alanine diminishes APPL2-mediated inhibition on insulin-dependent TBC1D1 phosphorylation on threonine 596 and the suppressive effects of TBC1D1 on insulin-induced glucose uptake and GLUT4 translocation to the plasma membrane in cultured myotubes. Therefore, the APPL2-TBC1D1 interaction is a key step to fine tune insulin-stimulated glucose uptake by regulating the membrane recruitment of GLUT4 in skeletal muscle.
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Affiliation(s)
- Kenneth K Y Cheng
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong Department of Medicine, The University of Hong Kong, Hong Kong
| | - Weidong Zhu
- Department of Medicine, The University of Hong Kong, Hong Kong
| | - Bin Chen
- Department of Medicine, The University of Hong Kong, Hong Kong
| | - Yu Wang
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong Department of Pharmacology & Pharmacy, The University of Hong Kong, Hong Kong
| | - Donghai Wu
- The Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Gary Sweeney
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Baile Wang
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong Department of Medicine, The University of Hong Kong, Hong Kong
| | - Karen S L Lam
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong Department of Medicine, The University of Hong Kong, Hong Kong
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong Department of Medicine, The University of Hong Kong, Hong Kong Department of Pharmacology & Pharmacy, The University of Hong Kong, Hong Kong
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12
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Pang X, Fan J, Zhang Y, Zhang K, Gao B, Ma J, Li J, Deng Y, Zhou Q, Egelman EH, Hsu VW, Sun F. A PH domain in ACAP1 possesses key features of the BAR domain in promoting membrane curvature. Dev Cell 2014; 31:73-86. [PMID: 25284369 PMCID: PMC4198613 DOI: 10.1016/j.devcel.2014.08.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 08/12/2014] [Accepted: 08/21/2014] [Indexed: 11/29/2022]
Abstract
The BAR (Bin-Amphiphysin-Rvs) domain undergoes dimerization to produce a curved protein structure, which superimposes onto membrane through electrostatic interactions to sense and impart membrane curvature. In some cases, a BAR domain also possesses an amphipathic helix that inserts into the membrane to induce curvature. ACAP1 (Arfgap with Coil coil, Ankyrin repeat, and PH domain protein 1) contains a BAR domain. Here, we show that this BAR domain can neither bind membrane nor impart curvature, but instead requires a neighboring PH (Pleckstrin Homology) domain to achieve these functions. Specific residues within the PH domain are responsible for both membrane binding and curvature generation. The BAR domain adjacent to the PH domain instead interacts with the BAR domains of neighboring ACAP1 proteins to enable clustering at the membrane. Thus, we have uncovered the molecular basis for an unexpected and unconventional collaboration between PH and BAR domains in membrane bending.
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Affiliation(s)
- Xiaoyun Pang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Fan
- Department of Physics and Materials Science, City University of Hong Kong, Hong Kong 999077, China
| | - Yan Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Kai Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Bingquan Gao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Ma
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Li
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Yuchen Deng
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiangjun Zhou
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Victor W Hsu
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
| | - Fei Sun
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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13
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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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Wang J, Deretic D. Molecular complexes that direct rhodopsin transport to primary cilia. Prog Retin Eye Res 2013; 38:1-19. [PMID: 24135424 DOI: 10.1016/j.preteyeres.2013.08.004] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/13/2013] [Accepted: 08/19/2013] [Indexed: 11/27/2022]
Abstract
Rhodopsin is a key molecular constituent of photoreceptor cells, yet understanding of how it regulates photoreceptor membrane trafficking and biogenesis of light-sensing organelles, the rod outer segments (ROS) is only beginning to emerge. Recently identified sequence of well-orchestrated molecular interactions of rhodopsin with the functional networks of Arf and Rab GTPases at multiple stages of intracellular targeting fits well into the complex framework of the biogenesis and maintenance of primary cilia, of which the ROS is one example. This review will discuss the latest progress in dissecting the molecular complexes that coordinate rhodopsin incorporation into ciliary-targeted carriers with the recruitment and activation of membrane tethering complexes and regulators of fusion with the periciliary plasma membrane. In addition to revealing the fundamental principals of ciliary membrane renewal, recent advances also provide molecular insight into the ways by which disruptions of the exquisitely orchestrated interactions lead to cilia dysfunction and result in human retinal dystrophies and syndromic diseases that affect multiple organs, including the eyes.
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Affiliation(s)
- Jing Wang
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Dusanka Deretic
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM 87131, USA; Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM 87131, USA.
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15
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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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16
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Abstract
Small GTPases are versatile temporal and spatial regulators of virtually all cellular processes including signal transduction, cytoskeleton dynamics and membrane trafficking. They function as molecular switches, aided by a multitude of regulatory and effector proteins that link them into functional networks. A picture is beginning to emerge whereupon scaffold proteins with many functional domains perform the regulatory and effector functions, thus allowing the ordered recruitment and activation of small GTPases. This leads to the formation of scaffolding patches that coordinate cargo concentration and capture, with the recruitment and activation of the membrane tethering complexes and fusion regulators. This review will focus on the crosstalk of Arf and Rab GTPases at the Golgi complex and the scaffolds that facilitate their activation during trafficking of sensory receptors to primary cilia. The evolutionary conservation of the GTPase cascades in ciliogenesis and yeast budding will be discussed.
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Affiliation(s)
- Dusanka Deretic
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM, USA.
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