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Voss L, Foster OK, Harper L, Morris C, Lavoy S, Brandt JN, Peloza K, Handa S, Maxfield A, Harp M, King B, Eichten V, Rambo FM, Hermann GJ. An ABCG Transporter Functions in Rab Localization and Lysosome-Related Organelle Biogenesis in Caenorhabditis elegans. Genetics 2020; 214:419-445. [PMID: 31848222 PMCID: PMC7017009 DOI: 10.1534/genetics.119.302900] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 12/11/2019] [Indexed: 12/20/2022] Open
Abstract
ABC transporters couple ATP hydrolysis to the transport of substrates across cellular membranes. This protein superfamily has diverse activities resulting from differences in their cargo and subcellular localization. Our work investigates the role of the ABCG family member WHT-2 in the biogenesis of gut granules, a Caenorhabditis elegans lysosome-related organelle. In addition to being required for the accumulation of birefringent material within gut granules, WHT-2 is necessary for the localization of gut granule proteins when trafficking pathways to this organelle are partially disrupted. The role of WHT-2 in gut granule protein targeting is likely linked to its function in Rab GTPase localization. We show that WHT-2 promotes the gut granule association of the Rab32 family member GLO-1 and the endolysosomal RAB-7, identifying a novel function for an ABC transporter. WHT-2 localizes to gut granules where it could play a direct role in controlling Rab localization. Loss of CCZ-1 and GLO-3, which likely function as a guanine nucleotide exchange factor (GEF) for GLO-1, lead to similar disruption of GLO-1 localization. We show that CCZ-1, like GLO-3, is localized to gut granules. WHT-2 does not direct the gut granule association of the GLO-1 GEF and our results point to WHT-2 functioning differently than GLO-3 and CCZ-1 Point mutations in WHT-2 that inhibit its transport activity, but not its subcellular localization, lead to the loss of GLO-1 from gut granules, while other WHT-2 activities are not completely disrupted, suggesting that WHT-2 functions in organelle biogenesis through transport-dependent and transport-independent activities.
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Affiliation(s)
- Laura Voss
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Olivia K Foster
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Logan Harper
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Caitlin Morris
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Sierra Lavoy
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - James N Brandt
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Kimberly Peloza
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Simran Handa
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Amanda Maxfield
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Marie Harp
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Brian King
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | | | - Fiona M Rambo
- Department of Biology, Lewis & Clark College, Portland, Oregon
| | - Greg J Hermann
- Department of Biology, Lewis & Clark College, Portland, Oregon
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Bidaud-Meynard A, Bossard F, Schnúr A, Fukuda R, Veit G, Xu H, Lukacs GL. Transcytosis maintains CFTR apical polarity in the face of constitutive and mutation-induced basolateral missorting. J Cell Sci 2019; 132:jcs.226886. [PMID: 30975917 DOI: 10.1242/jcs.226886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 04/02/2019] [Indexed: 12/22/2022] Open
Abstract
Apical polarity of cystic fibrosis transmembrane conductance regulator (CFTR) is essential for solute and water transport in secretory epithelia and can be impaired in human diseases. Maintenance of apical polarity in the face of CFTR non-polarized delivery and inefficient apical retention of mutant CFTRs lacking PDZ-domain protein (NHERF1, also known as SLC9A3R1) interaction, remains enigmatic. Here, we show that basolateral CFTR delivery originates from biosynthetic (∼35%) and endocytic (∼65%) recycling missorting. Basolateral channels are retrieved via basolateral-to-apical transcytosis (hereafter denoted apical transcytosis), enhancing CFTR apical expression by two-fold and suppressing its degradation. In airway epithelia, CFTR transcytosis is microtubule-dependent but independent of Myo5B, Rab11 proteins and NHERF1 binding to its C-terminal DTRL motif. Increased basolateral delivery due to compromised apical recycling and accelerated internalization upon impaired NHERF1-CFTR association is largely counterbalanced by efficient CFTR basolateral internalization and apical transcytosis. Thus, transcytosis represents a previously unrecognized, but indispensable, mechanism for maintaining CFTR apical polarity that acts by attenuating its constitutive and mutation-induced basolateral missorting.
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Affiliation(s)
| | - Florian Bossard
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Andrea Schnúr
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Ryosuke Fukuda
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Guido Veit
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Haijin Xu
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada .,Department of Biochemistry, McGill University, Montréal, QC, H3G 1Y6, Canada
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3
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Farinha CM, Matos P. Rab GTPases regulate the trafficking of channels and transporters - a focus on cystic fibrosis. Small GTPases 2017; 9:136-144. [PMID: 28463591 DOI: 10.1080/21541248.2017.1317700] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The amount of ion channels and transporters present at the plasma membrane is a crucial component of the overall regulation of ion transport. The number of channels present result from an intricate network of proteins that controls the late events of channel trafficking, such as endocytosis, recycling and targeting to lysosomal degradation. Small GTPases of the Rab family are key players in these processes thus contributing to regulation of fluid secretion and ion homeostasis. In epithelia, this involves mainly the balance between the chloride channel CFTR and the sodium channel ENaC, whose misfunction is a hallmark of cystic fibrosis - the commonest recessive disorder in Caucasians. Here, we review the role of GTPases in regulating trafficking of ion channels and transporters, comparing what is known for CFTR and ENaC with other types of channels. We also discuss how feasible would be to target the Rab machinery to handle a disorder such as CF.
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Affiliation(s)
- Carlos M Farinha
- a University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute , Campo Grande, Lisboa , Portugal
| | - Paulo Matos
- a University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute , Campo Grande, Lisboa , Portugal.,b Department of Human Genetics , National Health Institute 'Dr. Ricardo Jorge' , Av. Padre Cruz, Lisboa , Portugal
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4
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Chapter Five - Ubiquitination of Ion Channels and Transporters. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:161-223. [DOI: 10.1016/bs.pmbts.2016.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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5
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Pranke IM, Sermet-Gaudelus I. Biosynthesis of cystic fibrosis transmembrane conductance regulator. Int J Biochem Cell Biol 2014; 52:26-38. [DOI: 10.1016/j.biocel.2014.03.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 01/19/2023]
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Su H, Liu B, Fröhlich O, Ma H, Sands JM, Chen G. Small GTPase Rab14 down-regulates UT-A1 urea transport activity through enhanced clathrin-dependent endocytosis. FASEB J 2013; 27:4100-7. [PMID: 23796783 PMCID: PMC4046183 DOI: 10.1096/fj.13-229294] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 06/11/2013] [Indexed: 11/11/2022]
Abstract
The UT-A1 urea transporter plays an important role in the urinary concentration mechanism. However, the molecular mechanisms regarding UT-A1 trafficking, endocytosis, and degradation are still unclear. In this study, we identified the small GTPase Rab14 as a binding partner to the C terminus of UT-A1 in a yeast 2-hybrid assay. Interestingly, UT-A1 binding is preferential for the GDP-bound inactive form of Rab14. Coinjection of Rab14 in Xenopus oocytes results in a decrease of UT-A1 urea transport activity, suggesting that Rab14 acts as a negative regulator of UT-A1. We subsequently found that Rab14 reduces the cell membrane expression of UT-A1, as evidenced by cell surface biotinylation. This effect is blocked by chlorpromazine, an inhibitor of the clathrin-mediated endocytic pathway, but not by filipin, an inhibitor of the caveolin-mediated endocytic pathway. In kidney, Rab14 is mainly expressed in IMCD epithelial cells with a pattern identical to UT-A1 expression. Consistent with its role in participating in clathrin-mediated endocytosis, Rab14 localizes in nonlipid raft microdomains and codistributes with Rab5, a marker of the clathrin-mediated endocytic pathway. Taken together, our study suggests that Rab14, as a novel UT-A1 partner, may have an important regulatory function for UT-A1 urea transport activity in the kidney inner medulla.
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Affiliation(s)
- Hua Su
- 1Department of Physiology, Emory University School of Medicine, 615 Michael St., Atlanta, GA 30322, USA.
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Farinha CM, Matos P, Amaral MD. Control of cystic fibrosis transmembrane conductance regulator membrane trafficking: not just from the endoplasmic reticulum to the Golgi. FEBS J 2013; 280:4396-406. [PMID: 23773658 DOI: 10.1111/febs.12392] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/25/2013] [Accepted: 06/11/2013] [Indexed: 12/18/2022]
Abstract
Biogenesis of cystic fibrosis transmembrane conductance regulator (CFTR) starts with its cotranslational insertion into the membrane of the endoplasmic reticulum (ER) and core glycosylation. These initial events are followed by a complex succession of steps with the main goal of checking the overall quality of CFTR conformation in order to promote its exit from the ER through the secretory pathway. Failure to pass the various checkpoints of the ER quality control targets the most frequent disease-causing mutant protein (F508del-CFTR) for premature degradation. For wild-type CFTR that exits the ER, trafficking through the Golgi is the major site for glycan processing, although nonconventional trafficking pathways have also been described for CFTR. Once CFTR is at the cell surface, its stability is also controlled by multiple protein interactors, including Rab proteins, Rho small GTPases, and PDZ proteins. These regulate not only anterograde trafficking to the cell surface, but also endocytosis and recycling, thus achieving fine and tight modulation of CFTR plasma membrane levels. Exciting recent data have related autophagy and epithelial differentiation to the regulation of CFTR trafficking. Herein, we review the various checkpoints of the complex quality control along the secretory trafficking pathway and the associated pathways that are starting to be explored for the benefit of cystic fibrosis patients.
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Affiliation(s)
- Carlos M Farinha
- Faculty of Sciences, BioFIG - Centre for Biodiversity, Functional and Integrative Genomics, University of Lisboa, Portugal
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Cui Z, Zhang S. Regulation of the human ether-a-go-go-related gene (hERG) channel by Rab4 protein through neural precursor cell-expressed developmentally down-regulated protein 4-2 (Nedd4-2). J Biol Chem 2013; 288:21876-86. [PMID: 23792956 DOI: 10.1074/jbc.m113.461715] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes the pore-forming α-subunit of the rapidly activating delayed rectifier K(+) channel in the heart, which plays a critical role in cardiac action potential repolarization. Dysfunction of IKr causes long QT syndrome, a cardiac electrical disorder that predisposes affected individuals to fatal arrhythmias and sudden death. The homeostasis of hERG channels in the plasma membrane depends on a balance between protein synthesis and degradation. Our recent data indicate that hERG channels undergo enhanced endocytic degradation under low potassium (hypokalemia) conditions. The GTPase Rab4 is known to mediate rapid recycling of various internalized proteins to the plasma membrane. In the present study, we investigated the effect of Rab4 on the expression level of hERG channels. Our data revealed that overexpression of Rab4 decreases the expression level of hERG in the plasma membrane. Rab4 does not affect the expression level of the Kv1.5 or EAG K(+) channels. Mechanistically, our data demonstrate that overexpression of Rab4 increases the expression level of endogenous Nedd4-2, a ubiquitin ligase that targets hERG but not Kv1.5 or EAG channels for ubiquitination and degradation. Nedd4-2 undergoes self- ubiquitination and degradation. Rab4 interferes with Nedd4-2 degradation, resulting in an increased expression level of Nedd4-2, which targets hERG. In summary, the present study demonstrates a novel pathway for hERG regulation; Rab4 decreases the hERG density at the plasma membrane by increasing the endogenous Nedd4-2 expression.
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Affiliation(s)
- Zhi Cui
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
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Balse E, Steele DF, Abriel H, Coulombe A, Fedida D, Hatem SN. Dynamic of Ion Channel Expression at the Plasma Membrane of Cardiomyocytes. Physiol Rev 2012; 92:1317-58. [DOI: 10.1152/physrev.00041.2011] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cardiac myocytes are characterized by distinct structural and functional entities involved in the generation and transmission of the action potential and the excitation-contraction coupling process. Key to their function is the specific organization of ion channels and transporters to and within distinct membrane domains, which supports the anisotropic propagation of the depolarization wave. This review addresses the current knowledge on the molecular actors regulating the distinct trafficking and targeting mechanisms of ion channels in the highly polarized cardiac myocyte. In addition to ubiquitous mechanisms shared by other excitable cells, cardiac myocytes show unique specialization, illustrated by the molecular organization of myocyte-myocyte contacts, e.g., the intercalated disc and the gap junction. Many factors contribute to the specialization of the cardiac sarcolemma and the functional expression of cardiac ion channels, including various anchoring proteins, motors, small GTPases, membrane lipids, and cholesterol. The discovery of genetic defects in some of these actors, leading to complex cardiac disorders, emphasizes the importance of trafficking and targeting of ion channels to cardiac function. A major challenge in the field is to understand how these and other actors work together in intact myocytes to fine-tune ion channel expression and control cardiac excitability.
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Affiliation(s)
- Elise Balse
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - David F. Steele
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - Hugues Abriel
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - Alain Coulombe
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - David Fedida
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - Stéphane N. Hatem
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
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Butterworth MB, Edinger RS, Silvis MR, Gallo LI, Liang X, Apodaca G, Frizzell RA, Fizzell RA, Johnson JP. Rab11b regulates the trafficking and recycling of the epithelial sodium channel (ENaC). Am J Physiol Renal Physiol 2011; 302:F581-90. [PMID: 22129970 DOI: 10.1152/ajprenal.00304.2011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Expression of the epithelial sodium channel (ENaC) at the apical membrane of cortical collecting duct (CCD) principal cells is modulated by regulated trafficking mediated by vesicle insertion and retrieval. Small GTPases are known to facilitate vesicle trafficking, recycling, and membrane fusion events; however, little is known about the specific Rab family members that modify ENaC surface density. Using a mouse CCD cell line that endogenously expresses ENaC (mpkCCD), the channel was localized to both Rab11a- and Rab11b-positive endosomes by immunoisolation and confocal fluorescent microscopy. Expression of a dominant negative (DN) form of Rab11a or Rab11b significantly reduced the basal and cAMP-stimulated ENaC-dependent sodium (Na(+)) transport. The greatest reduction in Na(+) transport was observed with the expression of DN-Rab11b. Furthermore, small interfering RNA-mediated knockdown of each Rab11 isoform demonstrated the requirement for Rab11b in ENaC surface expression. These data indicate that Rab11b, and to a lesser extent Rab11a, is involved in establishing the constitutive and cAMP-stimulated Na(+) transport in mpkCCD cells.
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Affiliation(s)
- Michael B Butterworth
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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11
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Cianciola NL, Carlin CR, Kelley TJ. Molecular pathways for intracellular cholesterol accumulation: common pathogenic mechanisms in Niemann-Pick disease Type C and cystic fibrosis. Arch Biochem Biophys 2011; 515:54-63. [PMID: 21924233 PMCID: PMC3192251 DOI: 10.1016/j.abb.2011.08.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 08/29/2011] [Accepted: 08/30/2011] [Indexed: 12/11/2022]
Abstract
It has been less than two decades since the underlying genetic defects in Niemann-Pick disease Type C were first identified. These defects impair function of two proteins with a direct role in lipid trafficking, resulting in deposition of free cholesterol within late endosomal compartments and a multitude of effects on cell function and clinical manifestations. The rapid pace of research in this area has vastly improved our overall understanding of intracellular cholesterol homeostasis. Excessive cholesterol buildup has also been implicated in clinical manifestations associated with a number of genetically unrelated diseases including cystic fibrosis. Applying knowledge about anomalous cell signaling behavior in cystic fibrosis opens prospects for identifying similar previously unrecognized disease pathways in Niemann-Pick disease Type C. Recognition that Niemann-Pick disease Type C and cystic fibrosis both impair cholesterol regulatory pathways also provides a rationale for identifying common therapeutic targets.
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Affiliation(s)
- Nicholas L. Cianciola
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
| | - Cathleen R. Carlin
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
- Case Western Reserve University Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
| | - Thomas J. Kelley
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
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Ferrándiz-Huertas C, Fernández-Carvajal A, Ferrer-Montiel A. Rab4 interacts with the human P-glycoprotein and modulates its surface expression in multidrug resistant K562 cells. Int J Cancer 2010; 128:192-205. [PMID: 20209493 DOI: 10.1002/ijc.25310] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
P-glycoprotein (P-gp) is a plasma membrane glycoprotein that has been signaled as a primary cause of multidrug resistance (MDR) in tumors. We performed a yeast 2-hybrid screen using the C-terminal domain of P-gp and identified 2 small GTPases involved in vesicular trafficking, Rab4 and Rab14, which complex with P-gp. The overexpression of GFP-Rab4, either transiently or stably, but not of Rab14, in K562ADR cells decreased the presence of P-gp in the cell surface. As a result, expression of this GTPase reduced the MDR phenotype of K562ADR cells, by augmenting the intracellular accumulation of daunomycin (DNM). This effect was mimicked by the constitutively active Rab4Q72L mutant, but not by the dominant negative Rab4S27N mutant. Rab4 regulated excocytotic P-gp trafficking to the plasma membrane from intracellular compartments, and this modulation required the interaction of both proteins and the GTPase activity. Noteworthy, K562ADR cells exhibited a significant reduction of Rab4 levels, but not of other Rab GTPases, as compared with the sensitive parental cell line, suggesting that the development of the MDR phenotype in these cells involves upregulation of P-gp and a concomitant downregulation of proteins that regulate its surface expression. Attenuation of endogenous Rab4 levels in K562ADR by RNA interference enhanced the expression of P-gp in the cell surface, and reduced the uptake of DNM. Accordingly, these findings substantiate the notion that modulation of the temporal and spatial distribution of P-gp in cancer cells may be a valid therapeutic strategy to alleviate the MDR phenotype, and signal to Rab4 as a potential target.
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Affiliation(s)
- Clotilde Ferrándiz-Huertas
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Av de la Universidad s/n, 03202 Elche, Alicante, Spain
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Cayouette S, Bousquet SM, Francoeur N, Dupré É, Monet M, Gagnon H, Guedri YB, Lavoie C, Boulay G. Involvement of Rab9 and Rab11 in the intracellular trafficking of TRPC6. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:805-12. [DOI: 10.1016/j.bbamcr.2010.03.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 03/10/2010] [Accepted: 03/16/2010] [Indexed: 01/30/2023]
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14
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Gehring EM, Lam RS, Siraskar G, Koutsouki E, Seebohm G, Ureche ON, Ureche L, Baltaev R, Tavare JM, Lang F. PIKfyve upregulates CFTR activity. Biochem Biophys Res Commun 2009; 390:952-7. [DOI: 10.1016/j.bbrc.2009.10.084] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 10/15/2009] [Indexed: 02/01/2023]
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15
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Schonhoff CM, Thankey K, Webster CR, Wakabayashi Y, Wolkoff AW, Anwer MS. Rab4 facilitates cyclic adenosine monophosphate-stimulated bile acid uptake and Na+-taurocholate cotransporting polypeptide translocation. Hepatology 2008; 48:1665-70. [PMID: 18688880 PMCID: PMC2593787 DOI: 10.1002/hep.22495] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Cyclic adenosine monophosphate (cAMP) stimulates hepatic bile acid uptake by translocating sodium-taurocholate (TC) cotransporting polypeptide (Ntcp) from an endosomal compartment to the plasma membrane. Rab4 is associated with early endosomes and involved in vesicular trafficking. This study was designed to determine the role of Rab4 in cAMP-induced TC uptake and Ntcp translocation. HuH-Ntcp cells transiently transfected with empty vector, guanosine triphosphate (GTP) locked dominant active Rab4 (Rab4(GTP)), or guanosine diphosphate (GDP) locked dominant inactive Rab4 (Rab4(GDP)) were used to study the role of Rab4. Neither Rab4(GTP) nor Rab4(GDP) affected either basal TC uptake or plasma membrane Ntcp level. However, cAMP-induced increases in TC uptake and Ntcp translocation were enhanced by Rab4(GTP) and inhibited by Rab4(GDP). In addition, cAMP increased GTP binding to endogenous Rab4 in a time-dependent, but phosphoinositide-3-kinase-independent manner. CONCLUSION Taken together, these results suggest that cAMP-mediated phosphoinositide-3-kinase-independent activation of Rab4 facilitates Ntcp translocation in HuH-Ntcp cells.
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Affiliation(s)
- Christopher M. Schonhoff
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts 01536
| | - Krishna Thankey
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts 01536
| | - Cynthia R.L. Webster
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts 01536
| | | | - Allan W. Wolkoff
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - M. Sawkat Anwer
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts 01536
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Tanaka AR, Kano F, Yamamoto A, Ueda K, Murata M. Formation of cholesterol-enriched structures by aberrant intracellular accumulation of ATP-binding cassette transporter A1. Genes Cells 2008; 13:889-904. [DOI: 10.1111/j.1365-2443.2008.01213.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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17
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Bonecchi R, Borroni EM, Anselmo A, Doni A, Savino B, Mirolo M, Fabbri M, Jala VR, Haribabu B, Mantovani A, Locati M. Regulation of D6 chemokine scavenging activity by ligand- and Rab11-dependent surface up-regulation. Blood 2008; 112:493-503. [PMID: 18480427 DOI: 10.1182/blood-2007-08-108316] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The decoy receptor D6 plays a nonredundant role in the control of inflammatory processes through scavenging of inflammatory chemokines. However it remains unclear how it is regulated. Here we show that D6 scavenging activity relies on unique trafficking properties. Under resting conditions, D6 constitutively recycled through both a rapid wortmannin (WM)-sensitive and a slower brefeldin A (BFA)-sensitive pathway, maintaining low levels of surface expression that required both Rab4 and Rab11 activities. In contrast to "conventional" chemokine receptors that are down-regulated by cognate ligands, chemokine engagement induced a dose-dependent BFA-sensitive Rab11-dependent D6 re-distribution to the cell membrane and a corresponding increase in chemokine degradation rate. Thus, the energy-expensive constitutive D6 cycling through Rab11 vesicles allows a rapid, ligand concentration-dependent increase of chemokine scavenging activity by receptor redistribution to the plasma membrane. D6 is not regulated at a transcriptional level in a variety of cellular contexts, thus ligand-dependent optimization of its scavenger performance represents a rapid and unique mechanism allowing D6 to control inflammation.
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Affiliation(s)
- Raffaella Bonecchi
- Istituto Clinico Humanitas, Istituti di ricovero e cura a carattere scientifico (IRCCS), Rozzano, Italy.
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Pochynyuk O, Stockand JD, Staruschenko A. Ion channel regulation by Ras, Rho, and Rab small GTPases. Exp Biol Med (Maywood) 2008; 232:1258-65. [PMID: 17959838 DOI: 10.3181/0703-mr-76] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Regulation of ion channels by heterotrimeric guanosine triphosphatases (GTPases), activated by heptathelical membrane receptors, has been the focus of several recent reviews. In comparison, regulation of ion channels by small monomeric G proteins, activated by cytoplasmic guanine nucleotide exchange factors, has been less well reviewed. Small G proteins, molecular switches that control the activity of cellular and membrane proteins, regulate a wide variety of cell functions. Many upstream regulators and downstream effectors of small G proteins now have been isolated. Their modes of activation and action are understood. Recently, ion channels were recognized as physiologically important effectors of small GTPases. Recent advances in understanding how small G proteins regulate the intracellular trafficking and activity of ion channels are discussed here. We aim to provide critical insight into physiological control of ion channel function and the biological consequences of regulation of these important proteins by small, monomeric G proteins.
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Affiliation(s)
- Oleh Pochynyuk
- Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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Yasuda M, Niisato N, Miyazaki H, Iwasaki Y, Hama T, Dejima K, Hisa Y, Marunaka Y. Epithelial Na+ channel and ion transport in human nasal polyp and paranasal sinus mucosa. Biochem Biophys Res Commun 2007; 362:753-8. [PMID: 17765200 DOI: 10.1016/j.bbrc.2007.08.065] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 08/10/2007] [Indexed: 11/28/2022]
Abstract
The purpose of the present study is to characterize the ENaC-mediated Na+ absorption in human upper airway epithelia, nasal cavity, and paranasal sinus. To perform the purpose, we obtained epithelial cells from human nasal polyp (NP) and paranasal sinus mucosa (PSM) by endoscopic surgery. We measured the short-circuit current (I(sc)) sensitive to benzamil (a specific ENaC blocker). The benzamil-sensitive I(sc) (Na+ absorption) in NP was larger than that in PSM. The mRNA expression of three subunits of ENaC was as follows: alpha>beta>gamma in both tissue, NP and MS. The mRNA expression of gamma subunit of ENaC in NP was larger than that in PSM, but no difference of mRNA expression of alpha or beta ENaC subunit between NP and PSM was detected. We found correlation of the Na+ absorption to mRNA expression of gamma ENaC in NP and PSM. Forskolin diminished the Na+ absorption associated with an increase in Cl- secretion. These observations suggest that: (1) human NP absorbs more ENaC-mediated Na+ than PSM, (2) expression of gamma ENaC in plays a key role in the ENaC-mediated Na+ absorption in NP and PSM, and (3) cAMP diminishes the ENaC-mediated Na+ absorption by stimulating Cl- secretion (diminution of driving force for Na+ absorption) in NP and PSM.
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Affiliation(s)
- Makoto Yasuda
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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Saxena SK, Kaur S. Regulation of epithelial ion channels by Rab GTPases. Biochem Biophys Res Commun 2006; 351:582-7. [PMID: 17084813 DOI: 10.1016/j.bbrc.2006.10.087] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 10/19/2006] [Indexed: 10/24/2022]
Abstract
Epithelial ion channels are crucial to many of life's processes and disruption of their functions can lead to several disorders. Cystic fibrosis, an autosomal recessive disorder, is caused by defects in the biosynthesis or function of the CFTR chloride channel. Similarly, mutations in certain ENaC genes leading to increased or reduced channel activity cause diseases such as Liddle's syndrome or PHA. In order for ion channel proteins to be functional they need to be expressed on the plasma membrane. Thus, molecules that modulate the trafficking of ion channels to and from the membrane are of utmost significance. Among the numerous factors that regulate their functioning is a family of small GTPases known as Rab proteins. While Rabs have always played a pivotal role in membrane trafficking, their diversity of functions and plethora of interacting partners have lately been brought to light. Recent studies reveal that multiple Rab isoforms physically interact with and/or modulate the activity of several ion channels. Rab proteins have the ability to serve as molecular switches and many of the ion channels are regulated differentially by the GTP- or GDP-bound Rab isoforms. This review examines the role of Rab GTPases in the trafficking of ion channels, including CFTR, ENaC, TRPV5/6, and aquaporins, based on recent evidence.
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Affiliation(s)
- Sunil K Saxena
- Center for Cell and Molecular Biology, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
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Saxena SK, Kaur S. Rab27a negatively regulates CFTR chloride channel function in colonic epithelia: Involvement of the effector proteins in the regulatory mechanism. Biochem Biophys Res Commun 2006; 346:259-67. [PMID: 16762324 DOI: 10.1016/j.bbrc.2006.05.102] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Accepted: 05/17/2006] [Indexed: 10/24/2022]
Abstract
Cystic fibrosis, an autosomal recessive disorder, is caused by the disruption of biosynthesis or function of CFTR. CFTR regulatory mechanisms include channel transport to plasma membrane and protein-protein interactions. Rab proteins are small GTPases involved in vesicle transport, docking, and fusion. The colorectal epithelial HT-29 cells natively express CFTR and respond to cAMP with an increase in CFTR-mediated currents. DPC-inhibited currents could be completely eliminated with CFTR-specific SiRNA. Over-expression of Rab27a inhibited, while isoform specific SiRNA and Rab27a antibody stimulated CFTR-mediated currents in HT-29 cells. CFTR activity is inhibited both by Rab27a (Q78L) (constitutive active GTP-bound form of Rab27a) and Rab27a (T23N) (constitutive negative form that mimics the GDP-bound form). Rab27a mediated effects could be reversed by Rab27a-binding proteins, the synaptotagmin-like protein (SLP-5) and Munc13-4 accessory protein (a putative priming factor for exocytosis). The SLP reversal of Rab27a effect was restricted to C2A/C2B domains while the SHD motif imparted little more inhibition. The CFTR-mediated currents remain unaffected by Rab3 though SLP-5 appears to weakly bind it. The immunoprecipitation experiments suggest protein-protein interactions between Rab27a and CFTR. Rab27a appears to impair CFTR appearance at the cell surface by trapping CFTR in the intracellular compartments. Munc13-4 and SLP-5, on the other hand, limit Rab27a availability to CFTR, thus minimizing its effect on channel function. These observations decisively prove that Rab27a is involved in CFTR channel regulation through protein-protein interactions involving Munc13-4 and SLP-5 effector proteins, and thus could be a potential target for cystic fibrosis therapy.
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Affiliation(s)
- Sunil K Saxena
- Center for Cell and Molecular Biology, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
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