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Lin WY, Chung WY, Muallem S. The tether function of the anoctamins. Cell Calcium 2024; 121:102875. [PMID: 38701708 PMCID: PMC11166512 DOI: 10.1016/j.ceca.2024.102875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/17/2024] [Accepted: 03/20/2024] [Indexed: 05/05/2024]
Abstract
The core functions of the anoctamins are Cl- channel activity and phosphatidylserine (and perhaps other lipids) scrambling. These functions have been extensively studied in various tissues and cells. However, another function of the anoctamins that is less recognized and minimally explored is as tethers at membrane contact sites. This short review aims to examine evidence supporting the localization of the anoctamins at membrane contact sites, their tether properties, and their functions as tethers.
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Affiliation(s)
- Wei-Yin Lin
- From the Epithelial Signaling and Transport Section, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Woo Young Chung
- From the Epithelial Signaling and Transport Section, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shmuel Muallem
- From the Epithelial Signaling and Transport Section, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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2
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Weesner JA, Annunziata I, van de Vlekkert D, Robinson CG, Campos Y, Mishra A, Fremuth LE, Gomero E, Hu H, d'Azzo A. Altered GM1 catabolism affects NMDAR-mediated Ca 2+ signaling at ER-PM junctions and increases synaptic spine formation in a GM1-gangliosidosis model. Cell Rep 2024; 43:114117. [PMID: 38630590 PMCID: PMC11244331 DOI: 10.1016/j.celrep.2024.114117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 01/31/2024] [Accepted: 03/29/2024] [Indexed: 04/19/2024] Open
Abstract
Endoplasmic reticulum-plasma membrane (ER-PM) junctions mediate Ca2+ flux across neuronal membranes. The properties of these membrane contact sites are defined by their lipid content, but little attention has been given to glycosphingolipids (GSLs). Here, we show that GM1-ganglioside, an abundant GSL in neuronal membranes, is integral to ER-PM junctions; it interacts with synaptic proteins/receptors and regulates Ca2+ signaling. In a model of the neurodegenerative lysosomal storage disease, GM1-gangliosidosis, pathogenic accumulation of GM1 at ER-PM junctions due to β-galactosidase deficiency drastically alters neuronal Ca2+ homeostasis. Mechanistically, we show that GM1 interacts with the phosphorylated N-methyl D-aspartate receptor (NMDAR) Ca2+ channel, thereby increasing Ca2+ flux, activating extracellular signal-regulated kinase (ERK) signaling, and increasing the number of synaptic spines without increasing synaptic connectivity. Thus, GM1 clustering at ER-PM junctions alters synaptic plasticity and worsens the generalized neuronal cell death characteristic of GM1-gangliosidosis.
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Affiliation(s)
- Jason A Weesner
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA
| | - Ida Annunziata
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA; St. Jude Children's Research Hospital, Compliance Office, Memphis, TN 38105, USA
| | | | - Camenzind G Robinson
- St. Jude Children's Research Hospital, Cellular Imaging Shared Resource, Memphis, TN 38105, USA
| | - Yvan Campos
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA
| | - Ashutosh Mishra
- St. Jude Children's Research Hospital, Center for Proteomics and Metabolomics, Memphis, TN 38105, USA
| | - Leigh E Fremuth
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA
| | - Elida Gomero
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA
| | - Huimin Hu
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA
| | - Alessandra d'Azzo
- St. Jude Children's Research Hospital, Department of Genetics, Memphis, TN 38105, USA; University of Tennessee Health Science Center, Department of Anatomy and Physiology, Memphis, TN 38163, USA.
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3
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Deng Y, Zhu H, Wang Y, Dong Y, Du J, Yu Q, Li M. The Endoplasmic Reticulum-Plasma Membrane Tethering Protein Ice2 Controls Lipid Droplet Size via the Regulation of Phosphatidylcholine in Candida albicans. J Fungi (Basel) 2024; 10:87. [PMID: 38276033 PMCID: PMC10817647 DOI: 10.3390/jof10010087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/13/2024] [Accepted: 01/17/2024] [Indexed: 01/27/2024] Open
Abstract
Lipid droplets (LDs) are intracellular organelles that play important roles in cellular lipid metabolism; they change their sizes and numbers in response to both intracellular and extracellular signals. Changes in LD size reflect lipid synthesis and degradation and affect many cellular activities, including energy supply and membrane synthesis. Here, we focused on the function of the endoplasmic reticulum-plasma membrane tethering protein Ice2 in LD dynamics in the fungal pathogen Candida albicans (C. albicans). Nile red staining and size quantification showed that the LD size increased in the ice2Δ/Δ mutant, indicating the critical role of Ice2 in the regulation of LD dynamics. A lipid content analysis further demonstrated that the mutant had lower phosphatidylcholine levels. As revealed with GFP labeling and fluorescence microscopy, the methyltransferase Cho2, which is involved in phosphatidylcholine synthesis, had poorer localization in the plasma membrane in the mutant than in the wild-type strain. Interestingly, the addition of the phosphatidylcholine precursor choline led to the recovery of normal-sized LDs in the mutant. These results indicated that Ice2 regulates LD size by controlling intracellular phosphatidylcholine levels and that endoplasmic reticulum-plasma membrane tethering proteins play a role in lipid metabolism regulation in C. albicans. This study provides significant findings for further investigation of the lipid metabolism in fungi.
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Affiliation(s)
| | | | | | | | | | | | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.D.); (H.Z.); (Y.W.); (Y.D.); (J.D.)
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4
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Horvath JD, Casas M, Kutchukian C, Sánchez SC, Pergande MR, Cologna SM, Simó S, Dixon RE, Dickson EJ. α-Synuclein-dependent increases in PIP5K1γ drive inositol signaling to promote neurotoxicity. Cell Rep 2023; 42:113244. [PMID: 37838947 PMCID: PMC11010634 DOI: 10.1016/j.celrep.2023.113244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 08/09/2023] [Accepted: 09/25/2023] [Indexed: 10/17/2023] Open
Abstract
Anomalous aggregation of α-synuclein (α-Syn) is a pathological hallmark of many degenerative synucleinopathies including Lewy body dementia (LBD) and Parkinson's disease (PD). Despite its strong link to disease, the precise molecular mechanisms that link α-Syn aggregation to neurodegeneration have yet to be elucidated. Here, we find that elevated α-Syn leads to an increase in the plasma membrane (PM) phosphoinositide PI(4,5)P2, which precipitates α-Syn aggregation and drives toxic increases in mitochondrial Ca2+ and reactive oxygen species leading to neuronal death. Upstream of this toxic signaling pathway is PIP5K1γ, whose abundance and localization is enhanced at the PM by α-Syn-dependent increases in ARF6. Selective inhibition of PIP5K1γ or knockout of ARF6 in neurons rescues α-Syn aggregation and cellular phenotypes of toxicity. Collectively, our data suggest that modulation of phosphoinositide metabolism may be a therapeutic target to slow neurodegeneration for PD and other related neurodegenerative disorders.
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Affiliation(s)
- Jonathan D Horvath
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Maria Casas
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Candice Kutchukian
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Sara Creus Sánchez
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | | | | | - Sergi Simó
- Department of Cell Biology and Human Anatomy, University of California, Davis, Davis, CA 95616, USA
| | - Rose E Dixon
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA.
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5
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Casas M, Murray KD, Hino K, Vierra NC, Simó S, Trimmer JS, Dixon RE, Dickson EJ. NPC1-dependent alterations in K V2.1-Ca V1.2 nanodomains drive neuronal death in models of Niemann-Pick Type C disease. Nat Commun 2023; 14:4553. [PMID: 37507375 PMCID: PMC10382591 DOI: 10.1038/s41467-023-39937-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
Lysosomes communicate through cholesterol transfer at endoplasmic reticulum (ER) contact sites. At these sites, the Niemann Pick C1 cholesterol transporter (NPC1) facilitates the removal of cholesterol from lysosomes, which is then transferred to the ER for distribution to other cell membranes. Mutations in NPC1 result in cholesterol buildup within lysosomes, leading to Niemann-Pick Type C (NPC) disease, a progressive and fatal neurodegenerative disorder. The molecular mechanisms connecting NPC1 loss to NPC-associated neuropathology remain unknown. Here we show both in vitro and in an animal model of NPC disease that the loss of NPC1 function alters the distribution and activity of voltage-gated calcium channels (CaV). Underlying alterations in calcium channel localization and function are KV2.1 channels whose interactions drive calcium channel clustering to enhance calcium entry and fuel neurotoxic elevations in mitochondrial calcium. Targeted disruption of KV2-CaV interactions rescues aberrant CaV1.2 clustering, elevated mitochondrial calcium, and neurotoxicity in vitro. Our findings provide evidence that NPC is a nanostructural ion channel clustering disease, characterized by altered distribution and activity of ion channels at membrane contacts, which contribute to neurodegeneration.
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Affiliation(s)
- Maria Casas
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA
| | - Karl D Murray
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA
- Department of Psychiatry & Behavioral Sciences, School of Medicine, University of California, Davis, CA, USA
| | - Keiko Hino
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA, USA
| | - Nicholas C Vierra
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA
| | - Sergi Simó
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA, USA
| | - James S Trimmer
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA
| | - Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA.
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6
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Weesner JA, Annunziata I, van de Vlekkert D, Robinson CG, Campos Y, Mishra A, Fremuth LE, Gomero E, Hu H, d'Azzo A. Altered GM1 catabolism affects NMDAR-mediated Ca 2+ signaling at ER-PM junctions and increases synaptic spine formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548446. [PMID: 37503265 PMCID: PMC10369868 DOI: 10.1101/2023.07.10.548446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Endoplasmic reticulum-plasma membrane (ER-PM) junctions mediate Ca 2+ flux across neuronal membranes. The properties of these membrane contact sites are defined by their lipid content, but little attention has been given to glycosphingolipids (GSLs). Here, we show that GM1-ganglioside, an abundant GSL in neuronal membranes, is integral to ER-PM junctions; it interacts with synaptic proteins/receptors and regulates Ca 2+ signaling. In a model of the neurodegenerative lysosomal storage disease, GM1-gangliosidosis, pathogenic accumulation of GM1 at ER-PM junctions due to β-galactosidase deficiency drastically alters neuronal Ca 2+ homeostasis. Mechanistically, we show that GM1 interacts with the phosphorylated NMDAR Ca 2+ channel, thereby increasing Ca 2+ flux, activating ERK signaling, and increasing the number of synaptic spines without increasing synaptic connectivity. Thus, GM1 clustering at ER-PM junctions alters synaptic plasticity and exacerbates the generalized neuronal cell death characteristic of GM1-gangliosidosis.
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7
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Bura A, Čabrijan S, Đurić I, Bruketa T, Jurak Begonja A. A Plethora of Functions Condensed into Tiny Phospholipids: The Story of PI4P and PI(4,5)P 2. Cells 2023; 12:1411. [PMID: 37408244 PMCID: PMC10216963 DOI: 10.3390/cells12101411] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/08/2023] [Accepted: 05/09/2023] [Indexed: 07/07/2023] Open
Abstract
Phosphoinositides (PIs) are small, phosphorylated lipids that serve many functions in the cell. They regulate endo- and exocytosis, vesicular trafficking, actin reorganization, and cell mobility, and they act as signaling molecules. The most abundant PIs in the cell are phosphatidylinositol-4-monophosphate (PI4P) and phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. PI4P is mostly localized at the Golgi apparatus where it regulates the anterograde trafficking from the Golgi apparatus to the plasma membrane (PM), but it also localizes at the PM. On the other hand, the main localization site of PI(4,5)P2 is the PM where it regulates the formation of endocytic vesicles. The levels of PIs are regulated by many kinases and phosphatases. Four main kinases phosphorylate the precursor molecule phosphatidylinositol into PI4P, divided into two classes (PI4KIIα, PI4KIIβ, PI4KIIIα, and PI4KIIIβ), and three main kinases phosphorylate PI4P to form PI(4,5)P2 (PI4P5KIα, PI4P5KIβ, and PI4P5KIγ). In this review, we discuss the localization and function of the kinases that produce PI4P and PI(4,5)P2, as well as the localization and function of their product molecules with an overview of tools for the detection of these PIs.
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Affiliation(s)
| | | | | | | | - Antonija Jurak Begonja
- Laboratory of Hematopoiesis, Department of Biotechnology, University of Rijeka, R. Matejcic 2, 51000 Rijeka, Croatia
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8
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Thomas FB, Omnus DJ, Bader JM, Chung GH, Kono N, Stefan CJ. Tricalbin proteins regulate plasma membrane phospholipid homeostasis. Life Sci Alliance 2022; 5:5/8/e202201430. [PMID: 35440494 PMCID: PMC9018018 DOI: 10.26508/lsa.202201430] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 12/26/2022] Open
Abstract
The evolutionarily conserved extended synaptotagmin (E-Syt) proteins are calcium-activated lipid transfer proteins that function at contacts between the ER and plasma membrane (ER-PM contacts). However, roles of the E-Syt family members in PM lipid organisation remain incomplete. Among the E-Syt family, the yeast tricalbin (Tcb) proteins are essential for PM integrity upon heat stress, but it is not known how they contribute to PM maintenance. Using quantitative lipidomics and microscopy, we find that the Tcb proteins regulate phosphatidylserine homeostasis at the PM. Moreover, upon heat-induced membrane stress, Tcb3 co-localises with the PM protein Sfk1 that is implicated in PM phospholipid asymmetry and integrity. The Tcb proteins also control the PM targeting of the known phosphatidylserine effector Pkc1 upon heat-induced stress. Phosphatidylserine has evolutionarily conserved roles in PM organisation, integrity, and repair. We propose that phospholipid regulation is an ancient essential function of E-Syt family members required for PM integrity.
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Affiliation(s)
- Ffion B Thomas
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Deike J Omnus
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Jakob M Bader
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Gary Hc Chung
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Nozomu Kono
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Christopher J Stefan
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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9
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Guo Z, Jiang CH, Tong C, Yang Y, Wang Z, Lam SM, Wang D, Li R, Shui G, Shi YS, Liu JJ. Activity-dependent PI4P synthesis by PI4KIIIα regulates long-term synaptic potentiation. Cell Rep 2022; 38:110452. [PMID: 35235793 DOI: 10.1016/j.celrep.2022.110452] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/30/2021] [Accepted: 02/07/2022] [Indexed: 01/11/2023] Open
Abstract
Phosphatidylinositol 4-phosphate (PI4P) is a low abundant phospholipid with important roles in lipid transport and membrane trafficking. However, little is known of its metabolism and function in neurons. Here, we investigate its subcellular distribution and functional roles in dendrites of rodent hippocampal neurons during resting state and long-term synaptic potentiation (LTP). We show that neural activity causes dynamic reversible changes in PI4P metabolism in dendrites. Upon LTP induction, PI4KIIIα, a type III phosphatidylinositol 4-kinase, localizes to the dendritic plasma membrane (PM) in a calcium-dependent manner and causes substantial increase in the levels of PI4P. Acute inhibition of PI4KIIIα activity abolishes trafficking of the AMPA-type glutamate receptor to the PM during LTP induction, and silencing of PI4KIIIα expression in the hippocampal CA1 region causes severe impairment of LTP and long-term memory. Collectively, our results identify an essential role for PI4KIIIα-dependent PI4P synthesis in synaptic plasticity of central nervous system neurons.
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Affiliation(s)
- Zhenzhen Guo
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Chao-Hua Jiang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Chunfang Tong
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Yanrui Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Zehua Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Dou Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Rui Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Yun Stone Shi
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center of Nanjing University, Nanjing 210061, China
| | - Jia-Jia Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China.
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10
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Doumane M, Caillaud MC, Jaillais Y. Experimental manipulation of phosphoinositide lipids: from cells to organisms. Trends Cell Biol 2022; 32:445-461. [DOI: 10.1016/j.tcb.2022.01.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/14/2022]
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11
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Wang S, Yao L, Zhang W, Cheng Z, Hu C, Liu H, Yan Y, Shi A. AP-1 Recruits SMAP-1/SMAPs to the trans-Golgi Network to Promote Sorting in Polarized Epithelia. Front Cell Dev Biol 2021; 9:774401. [PMID: 34901019 PMCID: PMC8655793 DOI: 10.3389/fcell.2021.774401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 11/05/2021] [Indexed: 11/13/2022] Open
Abstract
Coordinated AP-1 and clathrin coat assembly mediate secretory sorting on the trans-Golgi network (TGN) during conventional secretion. Here we found that SMAP-1/SMAPs deficiency caused the apical protein ERM-1 to accumulate on the basolateral side of the TGN. In contrast, the basolateral protein SLCF-1 appeared abnormally on the apical membrane. SMAP-1 colocalized with AP-1 on the TGN. The integrity of AP-1 is required for the subcellular presence of SMAP-1. Moreover, we found that the loss of SMAP-1 reduced clathrin-positive structures in the cytosol, suggesting that SMAP-1 has a regulatory role in clathrin assembly on the TGN. Functional experiments showed that overexpressing clathrin effectively alleviated exocytic defects due to the lack of SMAP-1, corroborating the role of SMAP-1 in promoting the assembly of clathrin on the TGN. Together, our results suggested that the AP-1 complex regulates the TGN localization of SMAP-1, promoting clathrin assembly to ensure polarized conventional secretion in C. elegans intestinal epithelia.
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Affiliation(s)
- Shimin Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Longfeng Yao
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wenjuan Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zihang Cheng
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Can Hu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hang Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yanling Yan
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Cell Architecture Research Institute, Huazhong University of Science and Technology, Wuhan, China
| | - Anbing Shi
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Cell Architecture Research Institute, Huazhong University of Science and Technology, Wuhan, China
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12
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Ikhlef S, Lipp NF, Delfosse V, Fuggetta N, Bourguet W, Magdeleine M, Drin G. Functional analyses of phosphatidylserine/PI(4)P exchangers with diverse lipid species and membrane contexts reveal unanticipated rules on lipid transfer. BMC Biol 2021; 19:248. [PMID: 34801011 PMCID: PMC8606082 DOI: 10.1186/s12915-021-01183-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/04/2021] [Indexed: 11/14/2022] Open
Abstract
Background Lipid species are accurately distributed in the eukaryotic cell so that organelle and plasma membranes have an adequate lipid composition to support numerous cellular functions. In the plasma membrane, a precise regulation of the level of lipids such as phosphatidylserine, PI(4)P, and PI(4,5)P2, is critical for maintaining the signaling competence of the cell. Several lipid transfer proteins of the ORP/Osh family contribute to this fine-tuning by delivering PS, synthesized in the endoplasmic reticulum, to the plasma membrane in exchange for PI(4)P. To get insights into the role of these PS/PI(4)P exchangers in regulating plasma membrane features, we question how they selectively recognize and transfer lipid ligands with different acyl chains, whether these proteins exchange PS exclusively for PI(4)P or additionally for PI(4,5)P2, and how sterol abundance in the plasma membrane impacts their activity. Results We measured in vitro how the yeast Osh6p and human ORP8 transported PS and PI(4)P subspecies of diverse length and unsaturation degree between membranes by fluorescence-based assays. We established that the exchange activity of Osh6p and ORP8 strongly depends on whether these ligands are saturated or not, and is high with representative cellular PS and PI(4)P subspecies. Unexpectedly, we found that the speed at which these proteins individually transfer lipid ligands between membranes is inversely related to their affinity for them and that high-affinity ligands must be exchanged to be transferred more rapidly. Next we determined that Osh6p and ORP8 cannot use PI(4,5)P2 for exchange processes, because it is a low-affinity ligand, and do not transfer more PS into sterol-rich membranes. Conclusions Our study provides new insights into PS/PI(4)P exchangers by indicating the degree to which they can regulate the acyl chain composition of the PM, and how they control PM phosphoinositide levels. Moreover, we establish general rules on how the activity of lipid transfer proteins relates to their affinity for ligands. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01183-1.
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Affiliation(s)
- Souade Ikhlef
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France
| | - Nicolas-Frédéric Lipp
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France.,Current position: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Vanessa Delfosse
- Centre de Biologie Structurale, INSERM, CNRS, Université de Montpellier, Montpellier, France
| | - Nicolas Fuggetta
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France
| | - William Bourguet
- Centre de Biologie Structurale, INSERM, CNRS, Université de Montpellier, Montpellier, France
| | - Maud Magdeleine
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France
| | - Guillaume Drin
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France.
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13
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Tiscione SA, Casas M, Horvath JD, Lam V, Hino K, Ory DS, Santana LF, Simó S, Dixon RE, Dickson EJ. IP 3R-driven increases in mitochondrial Ca 2+ promote neuronal death in NPC disease. Proc Natl Acad Sci U S A 2021; 118:e2110629118. [PMID: 34580197 PMCID: PMC8501836 DOI: 10.1073/pnas.2110629118] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2021] [Indexed: 01/05/2023] Open
Abstract
Ca2+ is the most ubiquitous second messenger in neurons whose spatial and temporal elevations are tightly controlled to initiate and orchestrate diverse intracellular signaling cascades. Numerous neuropathologies result from mutations or alterations in Ca2+ handling proteins; thus, elucidating molecular pathways that shape Ca2+ signaling is imperative. Here, we report that loss-of-function, knockout, or neurodegenerative disease-causing mutations in the lysosomal cholesterol transporter, Niemann-Pick Type C1 (NPC1), initiate a damaging signaling cascade that alters the expression and nanoscale distribution of IP3R type 1 (IP3R1) in endoplasmic reticulum membranes. These alterations detrimentally increase Gq-protein coupled receptor-stimulated Ca2+ release and spontaneous IP3R1 Ca2+ activity, leading to mitochondrial Ca2+ cytotoxicity. Mechanistically, we find that SREBP-dependent increases in Presenilin 1 (PS1) underlie functional and expressional changes in IP3R1. Accordingly, expression of PS1 mutants recapitulate, while PS1 knockout abrogates Ca2+ phenotypes. These data present a signaling axis that links the NPC1 lysosomal cholesterol transporter to the damaging redistribution and activity of IP3R1 that precipitates cell death in NPC1 disease and suggests that NPC1 is a nanostructural disease.
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Affiliation(s)
- Scott A Tiscione
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Maria Casas
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Jonathan D Horvath
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Vincent Lam
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Keiko Hino
- Department of Cell Biology and Human Anatomy, University of California, Davis, CA 95616
| | - Daniel S Ory
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Sergi Simó
- Department of Cell Biology and Human Anatomy, University of California, Davis, CA 95616
| | - Rose E Dixon
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616;
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14
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Isolation of Mitochondria-Associated ER Membranes (MAMs), Synaptic MAMs, and Glycosphingolipid Enriched Microdomains (GEMs) from Brain Tissues and Neuronal Cells. Methods Mol Biol 2021. [PMID: 34080162 DOI: 10.1007/978-1-0716-1270-5_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Subcellular fractionation is a valuable procedure in cell biology to separate and purify various subcellular constituents from one another, i.e., nucleus, cytosol, membranes/organelles, and cytoskeleton. The procedure relies on the use of differential centrifugation of cell and tissue homogenates. Fractionated subcellular organelles may be subjected to additional purification steps that enable the isolation of specific cellular sub-compartments, including interorganellar membrane contact sites. Here we outline a protocol tailored to the isolation of mitochondria, mitochondria-associated ER membranes (MAMs), and glycosphingolipid enriched microdomains (GEMs) from the adult mouse brain, primary neurospheres, and murine embryonic fibroblasts (MEFs). We also provide a detailed protocol for the purification of synaptosomes and their corresponding MAMs .
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15
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Kutchukian C, Vivas O, Casas M, Jones JG, Tiscione SA, Simó S, Ory DS, Dixon RE, Dickson EJ. NPC1 regulates the distribution of phosphatidylinositol 4-kinases at Golgi and lysosomal membranes. EMBO J 2021; 40:e105990. [PMID: 34019311 PMCID: PMC8246069 DOI: 10.15252/embj.2020105990] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 03/11/2021] [Accepted: 03/19/2021] [Indexed: 12/15/2022] Open
Abstract
Cholesterol and phosphoinositides (PI) are two critically important lipids that are found in cellular membranes and dysregulated in many disorders. Therefore, uncovering molecular pathways connecting these essential lipids may offer new therapeutic insights. We report that loss of function of lysosomal Niemann-Pick Type C1 (NPC1) cholesterol transporter, which leads to neurodegenerative NPC disease, initiates a signaling cascade that alters the cholesterol/phosphatidylinositol 4-phosphate (PtdIns4P) countertransport cycle between Golgi-endoplasmic reticulum (ER), as well as lysosome-ER membrane contact sites (MCS). Central to these disruptions is increased recruitment of phosphatidylinositol 4-kinases-PI4KIIα and PI4KIIIβ-which boosts PtdIns4P metabolism at Golgi and lysosomal membranes. Aberrantly increased PtdIns4P levels elevate constitutive anterograde secretion from the Golgi complex, and mTORC1 recruitment to lysosomes. NPC1 disease mutations phenocopy the transporter loss of function and can be rescued by inhibition or knockdown of either key phosphoinositide enzymes or their recruiting partners. In summary, we show that the lysosomal NPC1 cholesterol transporter tunes the molecular content of Golgi and lysosome MCS to regulate intracellular trafficking and growth signaling in health and disease.
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Affiliation(s)
- Candice Kutchukian
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
| | - Oscar Vivas
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
- Present address:
Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | - Maria Casas
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
| | - Julia G Jones
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
| | - Scott A Tiscione
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
| | - Sergi Simó
- Department of Cell Biology & Human AnatomyUniversity of CaliforniaDavisCAUSA
| | - Daniel S Ory
- Department of Internal MedicineWashington University School of MedicineSt. LouisMOUSA
| | - Rose E Dixon
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
| | - Eamonn J Dickson
- Department of Physiology and Membrane BiologyUniversity of CaliforniaDavisCAUSA
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16
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Nakatsu F, Kawasaki A. Functions of Oxysterol-Binding Proteins at Membrane Contact Sites and Their Control by Phosphoinositide Metabolism. Front Cell Dev Biol 2021; 9:664788. [PMID: 34249917 PMCID: PMC8264513 DOI: 10.3389/fcell.2021.664788] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 05/06/2021] [Indexed: 01/10/2023] Open
Abstract
Lipids must be correctly transported within the cell to the right place at the right time in order to be fully functional. Non-vesicular lipid transport is mediated by so-called lipid transfer proteins (LTPs), which contain a hydrophobic cavity that sequesters lipid molecules. Oxysterol-binding protein (OSBP)-related proteins (ORPs) are a family of LTPs known to harbor lipid ligands, such as cholesterol and phospholipids. ORPs act as a sensor or transporter of those lipid ligands at membrane contact sites (MCSs) where two different cellular membranes are closely apposed. In particular, a characteristic functional property of ORPs is their role as a lipid exchanger. ORPs mediate counter-directional transport of two different lipid ligands at MCSs. Several, but not all, ORPs transport their lipid ligand from the endoplasmic reticulum (ER) in exchange for phosphatidylinositol 4-phosphate (PI4P), the other ligand, on apposed membranes. This ORP-mediated lipid “countertransport” is driven by the concentration gradient of PI4P between membranes, which is generated by its kinases and phosphatases. In this review, we will discuss how ORP function is tightly coupled to metabolism of phosphoinositides such as PI4P. Recent progress on the role of ORP-mediated lipid transport/countertransport at multiple MCSs in cellular functions will be also discussed.
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Affiliation(s)
- Fubito Nakatsu
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
| | - Asami Kawasaki
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
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17
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Claude-Taupin A, Morel E. Phosphoinositides: Functions in autophagy-related stress responses. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158903. [PMID: 33578048 DOI: 10.1016/j.bbalip.2021.158903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 01/29/2021] [Accepted: 02/06/2021] [Indexed: 01/02/2023]
Abstract
Phosphoinositides are key lipids in eukaryotes, regulating organelles' identity and function. Their synthesis and turnover require specific phosphorylation/dephosphorylation events that are ensured by dedicated lipid kinases and phosphatases, which modulate the structure of the inositol ring by adding or removing phosphates on positions 3, 4 or 5. Beside their implication in intracellular signalization and cytoskeleton dynamics, phosphoinositides are essential for vesicular transport along intracellular trafficking routes, by providing molecular scaffolds to membrane related events such as budding, fission or fusion. Robust and detailed literature demonstrated that some members of the phosphoinositides family are crucial for the autophagy pathway, acting as fine tuners and regulators. In this review, we discuss the known functions of phosphoinositides in autophagy canonical processes, such as during autophagosome formation, as well as the importance of phosphoinositides in organelle-based processes directly connected to the autophagic machinery, such as endosomal dynamics, ciliogenesis and innate immunity.
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Affiliation(s)
- Aurore Claude-Taupin
- Institut Necker Enfants-Malades (INEM), INSERM U1151-CNRS UMR 8253, Université de Paris, Paris, France
| | - Etienne Morel
- Institut Necker Enfants-Malades (INEM), INSERM U1151-CNRS UMR 8253, Université de Paris, Paris, France.
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18
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Biology of the mRNA Splicing Machinery and Its Dysregulation in Cancer Providing Therapeutic Opportunities. Int J Mol Sci 2021; 22:ijms22105110. [PMID: 34065983 PMCID: PMC8150589 DOI: 10.3390/ijms22105110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022] Open
Abstract
Dysregulation of messenger RNA (mRNA) processing—in particular mRNA splicing—is a hallmark of cancer. Compared to normal cells, cancer cells frequently present aberrant mRNA splicing, which promotes cancer progression and treatment resistance. This hallmark provides opportunities for developing new targeted cancer treatments. Splicing of precursor mRNA into mature mRNA is executed by a dynamic complex of proteins and small RNAs called the spliceosome. Spliceosomes are part of the supraspliceosome, a macromolecular structure where all co-transcriptional mRNA processing activities in the cell nucleus are coordinated. Here we review the biology of the mRNA splicing machinery in the context of other mRNA processing activities in the supraspliceosome and present current knowledge of its dysregulation in lung cancer. In addition, we review investigations to discover therapeutic targets in the spliceosome and give an overview of inhibitors and modulators of the mRNA splicing process identified so far. Together, this provides insight into the value of targeting the spliceosome as a possible new treatment for lung cancer.
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19
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Jung SR, Jiang Y, Seo JB, Chiu DT, Hille B, Koh DS. β-arrestin-dependent PI(4,5)P 2 synthesis boosts GPCR endocytosis. Proc Natl Acad Sci U S A 2021; 118:e2011023118. [PMID: 33879605 PMCID: PMC8092559 DOI: 10.1073/pnas.2011023118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
β-arrestins regulate many cellular functions including intracellular signaling and desensitization of G protein-coupled receptors (GPCRs). Previous studies show that β-arrestin signaling and receptor endocytosis are modulated by the plasma membrane phosphoinositide lipid phosphatidylinositol-(4, 5)-bisphosphate (PI(4,5)P2). We found that β-arrestin also helped promote synthesis of PI(4,5)P2 and up-regulated GPCR endocytosis. We studied these questions with the Gq-coupled protease-activated receptor 2 (PAR2), which activates phospholipase C, desensitizes quickly, and undergoes extensive endocytosis. Phosphoinositides were monitored and controlled in live cells using lipid-specific fluorescent probes and genetic tools. Applying PAR2 agonist initiated depletion of PI(4,5)P2, which then recovered during rapid receptor desensitization, giving way to endocytosis. This endocytosis could be reduced by various manipulations that depleted phosphoinositides again right after phosphoinositide recovery: PI(4)P, a precusor of PI(4,5)P2, could be depleted at either the Golgi or the plasma membrane (PM) using a recruitable lipid 4-phosphatase enzyme and PI(4,5)P2 could be depleted at the PM using a recruitable 5-phosphatase. Endocytosis required the phosphoinositides. Knock-down of β-arrestin revealed that endogenous β-arrestin normally doubles the rate of PIP5-kinase (PIP5K) after PAR2 desensitization, boosting PI(4,5)P2-dependent formation of clathrin-coated pits (CCPs) at the PM. Desensitized PAR2 receptors were swiftly immobilized when they encountered CCPs, showing a dwell time of ∼90 s, 100 times longer than for unactivated receptors. PAR2/β-arrestin complexes eventually accumulated around the edges or across the surface of CCPs promoting transient binding of PIP5K-Iγ. Taken together, β-arrestins can coordinate potentiation of PIP5K activity at CCPs to induce local PI(4,5)P2 generation that promotes recruitment of PI(4,5)P2-dependent endocytic machinery.
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Affiliation(s)
- Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195;
- Department of Chemistry, University of Washington, Seattle, WA 98195
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yifei Jiang
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Jong Bae Seo
- Department of Biosciences, Mokpo National University, Jeonnam 58554, Republic of Korea
- Department of Biomedicine, Health and Life Convergence Sciences, Mokpo National University, Jeonnam 58554, Republic of Korea
| | - Daniel T Chiu
- Department of Chemistry, University of Washington, Seattle, WA 98195
- Department of Bioengineering, University of Washington, Seattle, WA 98195
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Duk-Su Koh
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
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20
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Kruse M, Whitten RJ. Control of Neuronal Excitability by Cell Surface Receptor Density and Phosphoinositide Metabolism. Front Pharmacol 2021; 12:663840. [PMID: 33967808 PMCID: PMC8097148 DOI: 10.3389/fphar.2021.663840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 03/29/2021] [Indexed: 12/27/2022] Open
Abstract
Phosphoinositides are members of a family of minor phospholipids that make up about 1% of all lipids in most cell types. Despite their low abundance they have been found to be essential regulators of neuronal activities such as action potential firing, release and re-uptake of neurotransmitters, and interaction of cytoskeletal proteins with the plasma membrane. Activation of several different neurotransmitter receptors can deplete phosphoinositide levels by more than 90% in seconds, thereby profoundly altering neuronal behavior; however, despite the physiological importance of this mechanism we still lack a profound quantitative understanding of the connection between phosphoinositide metabolism and neuronal activity. Here, we present a model that describes phosphoinositide metabolism and phosphoinositide-dependent action potential firing in sympathetic neurons. The model allows for a simulation of activation of muscarinic acetylcholine receptors and its effects on phosphoinositide levels and their regulation of action potential firing in these neurons. In this paper, we describe the characteristics of the model, its calibration to experimental data, and use the model to analyze how alterations of surface density of muscarinic acetylcholine receptors or altered activity levels of a key enzyme of phosphoinositide metabolism influence action potential firing of sympathetic neurons. In conclusion, the model provides a comprehensive framework describing the connection between muscarinic acetylcholine signaling, phosphoinositide metabolism, and action potential firing in sympathetic neurons which can be used to study the role of these signaling systems in health and disease.
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Affiliation(s)
- Martin Kruse
- Department of Biology, Bates College, Lewiston, ME, United States
- Program in Neuroscience, Bates College, Lewiston, ME, United States
| | - Rayne J. Whitten
- Program in Neuroscience, Bates College, Lewiston, ME, United States
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21
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Casas M, Fadó R, Domínguez JL, Roig A, Kaku M, Chohnan S, Solé M, Unzeta M, Miñano-Molina AJ, Rodríguez-Álvarez J, Dickson EJ, Casals N. Sensing of nutrients by CPT1C controls SAC1 activity to regulate AMPA receptor trafficking. J Cell Biol 2021; 219:152088. [PMID: 32931550 PMCID: PMC7659714 DOI: 10.1083/jcb.201912045] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/21/2020] [Accepted: 06/18/2020] [Indexed: 12/21/2022] Open
Abstract
Carnitine palmitoyltransferase 1C (CPT1C) is a sensor of malonyl-CoA and is located in the ER of neurons. AMPA receptors (AMPARs) mediate fast excitatory neurotransmission in the brain and play a key role in synaptic plasticity. In the present study, we demonstrate across different metabolic stress conditions that modulate malonyl-CoA levels in cortical neurons that CPT1C regulates the trafficking of the major AMPAR subunit, GluA1, through the phosphatidyl-inositol-4-phosphate (PI(4)P) phosphatase SAC1. In normal conditions, CPT1C down-regulates SAC1 catalytic activity, allowing efficient GluA1 trafficking to the plasma membrane. However, under low malonyl-CoA levels, such as during glucose depletion, CPT1C-dependent inhibition of SAC1 is released, facilitating SAC1’s translocation to ER-TGN contact sites to decrease TGN PI(4)P pools and trigger GluA1 retention at the TGN. Results reveal that GluA1 trafficking is regulated by CPT1C sensing of malonyl-CoA and provide the first report of a SAC1 inhibitor. Moreover, they shed light on how nutrients can affect synaptic function and cognition.
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Affiliation(s)
- Maria Casas
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - Rut Fadó
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - José Luis Domínguez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - Aina Roig
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - Moena Kaku
- Department of Food and Life Science, Ibaraki University College of Agriculture, Ami, Ibaraki, Japan
| | - Shigeru Chohnan
- Department of Food and Life Science, Ibaraki University College of Agriculture, Ami, Ibaraki, Japan
| | - Montse Solé
- Biochemistry and Molecular Biology Department, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Mercedes Unzeta
- Biochemistry and Molecular Biology Department, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Alfredo Jesús Miñano-Molina
- Biochemistry and Molecular Biology Department, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Madrid, Spain
| | - José Rodríguez-Álvarez
- Biochemistry and Molecular Biology Department, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Madrid, Spain.,Department of Neuroscience, Albert Einstein College of Medicine, New York, NY
| | - Eamonn James Dickson
- Department of Physiology and Membrane Biology, University of California, School of Medicine, Davis, CA
| | - Núria Casals
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain.,Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain
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22
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Hewlett B, Singh NP, Vannier C, Galli T. ER-PM Contact Sites - SNARING Actors in Emerging Functions. Front Cell Dev Biol 2021; 9:635518. [PMID: 33681218 PMCID: PMC7928305 DOI: 10.3389/fcell.2021.635518] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The compartmentalisation achieved by confining cytoplasm into membrane-enclosed organelles in eukaryotic cells is essential for maintaining vital functions including ATP production, synthetic and degradative pathways. While intracellular organelles are highly specialised in these functions, the restricting membranes also impede exchange of molecules responsible for the synchronised and responsive cellular activities. The initial identification of contact sites between the ER and plasma membrane (PM) provided a potential candidate structure for communication between organelles without mixing by fusion. Over the past decades, research has revealed a far broader picture of the events. Membrane contact sites (MCSs) have been recognized as increasingly important actors in cell differentiation, plasticity and maintenance, and, upon dysfunction, responsible for pathological conditions such as cancer and neurodegenerative diseases. Present in multiple organelles and cell types, MCSs promote transport of lipids and Ca2+ homoeostasis, with a range of associated protein families. Interestingly, each MCS displays a unique molecular signature, adapted to organelle functions. This review will explore the literature describing the molecular components and interactions taking place at ER-PM contact sites, their functions, and implications in eukaryotic cells, particularly neurons, with emphasis on lipid transfer proteins and emerging function of SNAREs.
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Affiliation(s)
- Bailey Hewlett
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Neha Pratap Singh
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Christian Vannier
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Thierry Galli
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France.,GHU PARIS Psychiatrie and Neurosciences, Paris, France
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23
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Li C, Qian T, He R, Wan C, Liu Y, Yu H. Endoplasmic Reticulum-Plasma Membrane Contact Sites: Regulators, Mechanisms, and Physiological Functions. Front Cell Dev Biol 2021; 9:627700. [PMID: 33614657 PMCID: PMC7889955 DOI: 10.3389/fcell.2021.627700] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/13/2021] [Indexed: 12/13/2022] Open
Abstract
The endoplasmic reticulum (ER) forms direct membrane contact sites with the plasma membrane (PM) in eukaryotic cells. These ER-PM contact sites play essential roles in lipid homeostasis, ion dynamics, and cell signaling, which are carried out by protein-protein or protein-lipid interactions. Distinct tethering factors dynamically control the architecture of ER-PM junctions in response to intracellular signals or external stimuli. The physiological roles of ER-PM contact sites are dependent on a variety of regulators that individually or cooperatively perform functions in diverse cellular processes. This review focuses on proteins functioning at ER-PM contact sites and highlights the recent progress in their mechanisms and physiological roles.
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Affiliation(s)
- Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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24
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Xu J, Huang X. Lipid Metabolism at Membrane Contacts: Dynamics and Functions Beyond Lipid Homeostasis. Front Cell Dev Biol 2020; 8:615856. [PMID: 33425923 PMCID: PMC7786193 DOI: 10.3389/fcell.2020.615856] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 11/30/2020] [Indexed: 01/12/2023] Open
Abstract
Membrane contact sites (MCSs), regions where the membranes of two organelles are closely apposed, play critical roles in inter-organelle communication, such as lipid trafficking, intracellular signaling, and organelle biogenesis and division. First identified as “fraction X” in the early 90s, MCSs are now widely recognized to facilitate local lipid synthesis and inter-organelle lipid transfer, which are important for maintaining cellular lipid homeostasis. In this review, we discuss lipid metabolism and related cellular and physiological functions in MCSs. We start with the characteristics of lipid synthesis and breakdown at MCSs. Then we focus on proteins involved in lipid synthesis and turnover at these sites. Lastly, we summarize the cellular function of lipid metabolism at MCSs beyond mere lipid homeostasis, including the physiological meaning and relevance of MCSs regarding systemic lipid metabolism. This article is part of an article collection entitled: Coupling and Uncoupling: Dynamic Control of Membrane Contacts.
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Affiliation(s)
- Jiesi Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
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25
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Hawkins NA, Misra SN, Jurado M, Kang SK, Vierra NC, Nguyen K, Wren L, George AL, Trimmer JS, Kearney JA. Epilepsy and neurobehavioral abnormalities in mice with a dominant-negative KCNB1 pathogenic variant. Neurobiol Dis 2020; 147:105141. [PMID: 33132203 PMCID: PMC7725922 DOI: 10.1016/j.nbd.2020.105141] [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: 07/25/2020] [Revised: 10/04/2020] [Accepted: 10/12/2020] [Indexed: 11/23/2022] Open
Abstract
Developmental and epileptic encephalopathies (DEE) are a group of severe epilepsies that usually present with intractable seizures, developmental delay, and often have elevated risk for premature mortality. Numerous genes have been identified as a monogenic cause of DEE, including KCNB1. The voltage-gated potassium channel Kv2.1, encoded by KCNB1, is primarily responsible for delayed rectifier potassium currents that are important regulators of excitability in electrically excitable cells, including neurons. In addition to its canonical role as a voltage-gated potassium conductance, Kv2.1 also serves a highly conserved structural function organizing endoplasmic reticulum-plasma membrane junctions clustered in the soma and proximal dendrites of neurons. The de novo pathogenic variant KCNB1-p.G379R was identified in an infant with epileptic spasms, and atonic, focal and tonic-clonic seizures that were refractory to treatment with standard antiepileptic drugs. Previous work demonstrated deficits in potassium conductance, but did not assess non-conducting functions. To determine if the G379R variant affected Kv2.1 clustering at endoplasmic reticulum-plasma membrane junctions, Kv2.1-G379R was expressed in HEK293T cells. Kv2.1-G379R expression did not induce formation of endoplasmic reticulum-plasma membrane junctions, and co-expression of Kv2.1-G379R with Kv2.1-wild-type lowered induction of these structures relative to Kv2.1-WT alone, consistent with a dominant negative effect. To model this variant in vivo, we introduced Kcnb1G379R into mice using CRISPR/Cas9 genome editing. We characterized neuronal expression, neurological and neurobehavioral phenotypes of Kcnb1G379R/+ (Kcnb1R/+) and Kcnb1G379R/G379R (Kcnb1R/R) mice. Immunohistochemistry studies on brains from Kcnb1+/+, Kcnb1R/+ and Kcnb1R/R mice revealed genotype-dependent differences in the expression levels of Kv2.1 protein, as well as associated Kv2.2 and AMIGO-1 proteins. Kcnb1R/+ and Kcnb1R/R mice displayed profound hyperactivity, repetitive behaviors, impulsivity and reduced anxiety. Spontaneous seizures were observed in Kcnb1R/R mice, as well as seizures induced by exposure to novel environments and/ or handling. Both Kcnb1R/+ and Kcnb1R/R mutants were more susceptible to proconvulsant-induced seizures. In addition, both Kcnb1R/+ and Kcnb1R/R mice exhibited abnormal interictal EEG activity, including isolated spike and slow waves. Overall, the Kcnb1G379R mice recapitulate many features observed in individuals with DEE due to pathogenic variants in KCNB1. This new mouse model of KCNB1-associated DEE will be valuable for improving the understanding of the underlying pathophysiology and will provide a valuable tool for the development of therapies to treat this pharmacoresistant DEE.
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Affiliation(s)
- Nicole A Hawkins
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Sunita N Misra
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America; Ann & Robert H. Lurie Children's Hospital of Chicago Chicago, IL 60611, United States of America
| | - Manuel Jurado
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Seok Kyu Kang
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Nicholas C Vierra
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America; Department of preceding Physiology and Membrane Biology, University of California, Davis, CA 95616, United States of America
| | - Kimberly Nguyen
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America
| | - Lisa Wren
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - James S Trimmer
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America; Department of preceding Physiology and Membrane Biology, University of California, Davis, CA 95616, United States of America
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America.
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26
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Wu HD, Kikuchi M, Dagliyan O, Aragaki AK, Nakamura H, Dokholyan NV, Umehara T, Inoue T. Rational design and implementation of a chemically inducible heterotrimerization system. Nat Methods 2020; 17:928-936. [PMID: 32747768 PMCID: PMC9936427 DOI: 10.1038/s41592-020-0913-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 07/06/2020] [Indexed: 12/11/2022]
Abstract
Chemically inducible dimerization (CID) uses a small molecule to induce binding of two different proteins. CID tools such as the FK506-binding protein-FKBP-rapamycin-binding- (FKBP-FRB)-rapamycin system have been widely used to probe molecular events inside and outside cells. While various CID tools are available, chemically inducible trimerization (CIT) does not exist, due to inherent challenges in designing a chemical that simultaneously binds three proteins with high affinity and specificity. Here, we developed CIT by rationally splitting FRB and FKBP. Cellular and structural datasets showed efficient trimerization of split pairs of FRB or FKBP with full-length FKBP or FRB, respectively, by rapamycin. CIT rapidly induced tri-organellar junctions and perturbed intended membrane lipids exclusively at select membrane contact sites. By conferring one additional condition to what is achievable with CID, CIT expands the types of manipulation in single live cells to address cell biology questions otherwise intractable and engineer cell functions for future synthetic biology applications.
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Affiliation(s)
- Helen D. Wu
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205,Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Masaki Kikuchi
- Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa 230-0045, Japan
| | - Onur Dagliyan
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Adam K. Aragaki
- Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD 21205,Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Hideki Nakamura
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205,Present address: Kyoto University Graduate School of Engineering, Department of Synthetic Chemistry and Biological Chemistry, Katsura Int’tech Center, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8530, Japan
| | - Nikolay V. Dokholyan
- Departments of Pharmacology and Biochemistry & Molecular Biology, Penn State University College of Medicine, Hershey, Pennsylvania,Departments of Chemistry and Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania
| | - Takashi Umehara
- Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa, Japan.
| | - Takanari Inoue
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA. .,Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD, USA. .,Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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27
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Zaman MF, Nenadic A, Radojičić A, Rosado A, Beh CT. Sticking With It: ER-PM Membrane Contact Sites as a Coordinating Nexus for Regulating Lipids and Proteins at the Cell Cortex. Front Cell Dev Biol 2020; 8:675. [PMID: 32793605 PMCID: PMC7387695 DOI: 10.3389/fcell.2020.00675] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/03/2020] [Indexed: 12/31/2022] Open
Abstract
Membrane contact sites between the cortical endoplasmic reticulum (ER) and the plasma membrane (PM) provide a direct conduit for small molecule transfer and signaling between the two largest membranes of the cell. Contact is established through ER integral membrane proteins that physically tether the two membranes together, though the general mechanism is remarkably non-specific given the diversity of different tethering proteins. Primary tethers including VAMP-associated proteins (VAPs), Anoctamin/TMEM16/Ist2p homologs, and extended synaptotagmins (E-Syts), are largely conserved in most eukaryotes and are both necessary and sufficient for establishing ER-PM association. In addition, other species-specific ER-PM tether proteins impart unique functional attributes to both membranes at the cell cortex. This review distils recent functional and structural findings about conserved and species-specific tethers that form ER-PM contact sites, with an emphasis on their roles in the coordinate regulation of lipid metabolism, cellular structure, and responses to membrane stress.
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Affiliation(s)
- Mohammad F Zaman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Aleksa Nenadic
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Ana Radojičić
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.,Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Abel Rosado
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Christopher T Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.,The Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC, Canada
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28
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Bohnert M. Tether Me, Tether Me Not—Dynamic Organelle Contact Sites in Metabolic Rewiring. Dev Cell 2020; 54:212-225. [DOI: 10.1016/j.devcel.2020.06.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/17/2020] [Accepted: 06/20/2020] [Indexed: 02/04/2023]
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29
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Banerjee S, Kane PM. Regulation of V-ATPase Activity and Organelle pH by Phosphatidylinositol Phosphate Lipids. Front Cell Dev Biol 2020; 8:510. [PMID: 32656214 PMCID: PMC7324685 DOI: 10.3389/fcell.2020.00510] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/28/2020] [Indexed: 12/14/2022] Open
Abstract
Luminal pH and the distinctive distribution of phosphatidylinositol phosphate (PIP) lipids are central identifying features of organelles in all eukaryotic cells that are also critical for organelle function. V-ATPases are conserved proton pumps that populate and acidify multiple organelles of the secretory and the endocytic pathway. Complete loss of V-ATPase activity causes embryonic lethality in higher animals and conditional lethality in yeast, while partial loss of V-ATPase function is associated with multiple disease states. On the other hand, many cancer cells increase their virulence by upregulating V-ATPase expression and activity. The pH of individual organelles is tightly controlled and essential for function, but the mechanisms for compartment-specific pH regulation are not completely understood. There is substantial evidence indicating that the PIP content of membranes influences organelle pH. We present recent evidence that PIPs interact directly with subunit isoforms of the V-ATPase to dictate localization of V-ATPase subpopulations and participate in their regulation. In yeast cells, which have only one set of organelle-specific V-ATPase subunit isoforms, the Golgi-enriched lipid PI(4)P binds to the cytosolic domain of the Golgi-enriched a-subunit isoform Stv1, and loss of PI(4)P binding results in mislocalization of Stv1-containing V-ATPases from the Golgi to the vacuole/lysosome. In contrast, levels of the vacuole/lysosome-enriched signaling lipid PI(3,5)P2 affect assembly and activity of V-ATPases containing the Vph1 a-subunit isoform. Mutations in the Vph1 isoform that disrupt the lipid interaction increase sensitivity to stress. These studies have decoded “zip codes” for PIP lipids in the cytosolic N-terminal domain of the a-subunit isoforms of the yeast V-ATPase, and similar interactions between PIP lipids and the V-ATPase subunit isoforms are emerging in higher eukaryotes. In addition to direct effects on the V-ATPase, PIP lipids are also likely to affect organelle pH indirectly, through interactions with other membrane transporters. We discuss direct and indirect effects of PIP lipids on organelle pH, and the functional consequences of the interplay between PIP lipid content and organelle pH.
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Affiliation(s)
- Subhrajit Banerjee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
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30
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Ahuja M, Chung WY, Lin WY, McNally BA, Muallem S. Ca 2+ Signaling in Exocrine Cells. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035279. [PMID: 31636079 DOI: 10.1101/cshperspect.a035279] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Calcium (Ca2+) and cyclic AMP (cAMP) signaling cross talk and synergize to stimulate the cardinal functions of exocrine cells, regulated exocytosis, and fluid and electrolyte secretion. This physiological process requires the organization of the two signaling pathways into complexes at defined cellular domains and close placement. Such domains are formed by membrane contact sites (MCS). This review discusses the basic properties of Ca2+ signaling in exocrine cells, the role of MCS in the organization of cell signaling and in cross talk and synergism between the Ca2+ and cAMP signaling pathways and, finally, the mechanism by which the Ca2+ and cAMP pathways synergize to stimulate epithelial fluid and electrolyte secretion.
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Affiliation(s)
- Malini Ahuja
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Woo Young Chung
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Wei-Yin Lin
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Beth A McNally
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
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31
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Pemberton JG, Kim YJ, Balla T. Integrated regulation of the phosphatidylinositol cycle and phosphoinositide-driven lipid transport at ER-PM contact sites. Traffic 2019; 21:200-219. [PMID: 31650663 DOI: 10.1111/tra.12709] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/02/2019] [Accepted: 10/16/2019] [Indexed: 12/20/2022]
Abstract
Among the structural phospholipids that form the bulk of eukaryotic cell membranes, phosphatidylinositol (PtdIns) is unique in that it also serves as the common precursor for low-abundance regulatory lipids, collectively referred to as polyphosphoinositides (PPIn). The metabolic turnover of PPIn species has received immense attention because of the essential functions of these lipids as universal regulators of membrane biology and their dysregulation in numerous human pathologies. The diverse functions of PPIn lipids occur, in part, by orchestrating the spatial organization and conformational dynamics of peripheral or integral membrane proteins within defined subcellular compartments. The emerging role of stable contact sites between adjacent membranes as specialized platforms for the coordinate control of ion exchange, cytoskeletal dynamics, and lipid transport has also revealed important new roles for PPIn species. In this review, we highlight the importance of membrane contact sites formed between the endoplasmic reticulum (ER) and plasma membrane (PM) for the integrated regulation of PPIn metabolism within the PM. Special emphasis will be placed on non-vesicular lipid transport during control of the PtdIns biosynthetic cycle as well as toward balancing the turnover of the signaling PPIn species that define PM identity.
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Affiliation(s)
- Joshua G Pemberton
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
| | - Yeun Ju Kim
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
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32
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Masone MC, Morra V, Venditti R. Illuminating the membrane contact sites between the endoplasmic reticulum and the trans-Golgi network. FEBS Lett 2019; 593:3135-3148. [PMID: 31610025 DOI: 10.1002/1873-3468.13639] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 12/22/2022]
Abstract
Membrane contact sites (MCSs) between different organelles have been identified and extensively studied over the last decade. Several classes of MCSs have now well-established roles, although the contacts between the endoplasmic reticulum (ER) and the trans-side of the Golgi network (TGN) have long remained elusive. Until recently, the study of ER-TGN contact sites has represented a major challenge in the field, as a result of the lack of suitable visualization and isolation techniques. Only in the last 5 years has the combination of advanced technologies and innovative approaches permitted the identification of new molecular players and the functions of ER-TGN MCSs that couple lipid metabolism and anterograde transport. Although much has yet to be discovered, it is now established that ER-TGN MCSs control phosphatidyl-4-phosphate homeostasis by coupling the cis and the trans activity of the ER-resident 4-phosphatase Sac1. In this review, we focus on recent advances on the composition and function of ER-TGN MCSs.
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Affiliation(s)
| | - Valentina Morra
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Rossella Venditti
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.,Department of Molecular Medicine and Medical Biotechnology, Medical School, University of Napoli Federico II, Naples, Italy
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33
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Kirmiz M, Gillies TE, Dickson EJ, Trimmer JS. Neuronal ER-plasma membrane junctions organized by Kv2-VAP pairing recruit Nir proteins and affect phosphoinositide homeostasis. J Biol Chem 2019; 294:17735-17757. [PMID: 31594866 DOI: 10.1074/jbc.ra119.007635] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 10/02/2019] [Indexed: 12/21/2022] Open
Abstract
The association of plasma membrane (PM)-localized voltage-gated potassium (Kv2) channels with endoplasmic reticulum (ER)-localized vesicle-associated membrane protein-associated proteins VAPA and VAPB defines ER-PM junctions in mammalian brain neurons. Here, we used proteomics to identify proteins associated with Kv2/VAP-containing ER-PM junctions. We found that the VAP-interacting membrane-associated phosphatidylinositol (PtdIns) transfer proteins PYK2 N-terminal domain-interacting receptor 2 (Nir2) and Nir3 specifically associate with Kv2.1 complexes. When coexpressed with Kv2.1 and VAPA in HEK293T cells, Nir2 colocalized with cell-surface-conducting and -nonconducting Kv2.1 isoforms. This was enhanced by muscarinic-mediated PtdIns(4,5)P2 hydrolysis, leading to dynamic recruitment of Nir2 to Kv2.1 clusters. In cultured rat hippocampal neurons, exogenously expressed Nir2 did not strongly colocalize with Kv2.1, unless exogenous VAPA was also expressed, supporting the notion that VAPA mediates the spatial association of Kv2.1 and Nir2. Immunolabeling signals of endogenous Kv2.1, Nir2, and VAP puncta were spatially correlated in cultured neurons. Fluorescence-recovery-after-photobleaching experiments revealed that Kv2.1, VAPA, and Nir2 have comparable turnover rates at ER-PM junctions, suggesting that they form complexes at these sites. Exogenous Kv2.1 expression in HEK293T cells resulted in significant differences in the kinetics of PtdIns(4,5)P2 recovery following repetitive muscarinic stimulation, with no apparent impact on resting PtdIns(4,5)P2 or PtdIns(4)P levels. Finally, the brains of Kv2.1-knockout mice had altered composition of PtdIns lipids, suggesting a crucial role for native Kv2.1-containing ER-PM junctions in regulating PtdIns lipid metabolism in brain neurons. These results suggest that ER-PM junctions formed by Kv2 channel-VAP pairing regulate PtdIns lipid homeostasis via VAP-associated PtdIns transfer proteins.
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Affiliation(s)
- Michael Kirmiz
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616
| | - Taryn E Gillies
- Department of Bioengineering, Stanford University, Stanford, California 94305
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, California 95616
| | - James S Trimmer
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616 .,Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, California 95616
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34
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Junctophilin Proteins Tether a Cav1-RyR2-KCa3.1 Tripartite Complex to Regulate Neuronal Excitability. Cell Rep 2019; 28:2427-2442.e6. [DOI: 10.1016/j.celrep.2019.07.075] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/20/2019] [Accepted: 07/19/2019] [Indexed: 12/12/2022] Open
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35
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Jha A, Chung WY, Vachel L, Maleth J, Lake S, Zhang G, Ahuja M, Muallem S. Anoctamin 8 tethers endoplasmic reticulum and plasma membrane for assembly of Ca 2+ signaling complexes at the ER/PM compartment. EMBO J 2019; 38:embj.2018101452. [PMID: 31061173 DOI: 10.15252/embj.2018101452] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 12/18/2022] Open
Abstract
Communication and material transfer between membranes and organelles take place at membrane contact sites (MCSs). MCSs between the ER and PM, the ER/PM junctions, are the sites where the ER Ca2+ sensor STIM1 and the PM Ca2+ influx channel Orai1 cluster. MCSs are formed by tether proteins that bridge the opposing membranes, but the identity and role of these tethers in receptor-evoked Ca2+ signaling is not well understood. Here, we identified Anoctamin 8 (ANO8) as a key tether in the formation of the ER/PM junctions that is essential for STIM1-STIM1 interaction and STIM1-Orai1 interaction and channel activation at a ER/PM PI(4,5)P2-rich compartment. Moreover, ANO8 assembles all core Ca2+ signaling proteins: Orai1, PMCA, STIM1, IP3 receptors, and SERCA2 at the ER/PM junctions to mediate a novel form of Orai1 channel inactivation by markedly facilitating SERCA2-mediated Ca2+ influx into the ER. This controls the efficiency of receptor-stimulated Ca2+ signaling, Ca2+ oscillations, and duration of Orai1 activity to prevent Ca2+ toxicity. These findings reveal the central role of MCSs in determining efficiency and fidelity of cell signaling.
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Affiliation(s)
- Archana Jha
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Woo Young Chung
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Laura Vachel
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Jozsef Maleth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Sarah Lake
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Guofeng Zhang
- Trans-NIH Shared Resource on Biomedical Engineering and Physical Science (BEPS) National Institute of Biomedical Imaging & Bioengineering, Bethesda, MD, USA
| | - Malini Ahuja
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Shmuel Muallem
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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36
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Definition of phosphoinositide distribution in the nanoscale. Curr Opin Cell Biol 2019; 57:33-39. [DOI: 10.1016/j.ceb.2018.10.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/18/2018] [Accepted: 10/30/2018] [Indexed: 11/20/2022]
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37
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Scorrano L, De Matteis MA, Emr S, Giordano F, Hajnóczky G, Kornmann B, Lackner LL, Levine TP, Pellegrini L, Reinisch K, Rizzuto R, Simmen T, Stenmark H, Ungermann C, Schuldiner M. Coming together to define membrane contact sites. Nat Commun 2019; 10:1287. [PMID: 30894536 PMCID: PMC6427007 DOI: 10.1038/s41467-019-09253-3] [Citation(s) in RCA: 423] [Impact Index Per Article: 84.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 02/21/2019] [Indexed: 12/14/2022] Open
Abstract
Close proximities between organelles have been described for decades. However, only recently a specific field dealing with organelle communication at membrane contact sites has gained wide acceptance, attracting scientists from multiple areas of cell biology. The diversity of approaches warrants a unified vocabulary for the field. Such definitions would facilitate laying the foundations of this field, streamlining communication and resolving semantic controversies. This opinion, written by a panel of experts in the field, aims to provide this burgeoning area with guidelines for the experimental definition and analysis of contact sites. It also includes suggestions on how to operationally and tractably measure and analyze them with the hope of ultimately facilitating knowledge production and dissemination within and outside the field of contact-site research.
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Affiliation(s)
- Luca Scorrano
- Venetian Institute of Molecular Medicine, Department of Biology, University of Padua, Padua, Italy.
| | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Naples, Italy
| | - Scott Emr
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Francesca Giordano
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Sud University, Paris-Saclay University, Gif-sur-Yvette cedex, 91198, France.
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Benoît Kornmann
- University of Oxford, Department of Biochemistry, South Parks Road, Ox1 3QU, Oxford, United Kingdom
| | - Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA
| | - Tim P Levine
- UCL Institute of Ophthalmology, London, EC1V 9EL, UK
| | - Luca Pellegrini
- Department of Molecular Biology, Medical Biochemistry, and Pathology, Universitè Laval, Quebec, QC, Canada
| | - Karin Reinisch
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Thomas Simmen
- University of Alberta, Faculty of Medicine and Dentistry, Department of Cell Biology, Edmonton, AB, T6G2H7, Canada
| | - Harald Stenmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Montebello, N-0379, Oslo, Norway
| | - Christian Ungermann
- Department of Biology/Chemistry, University of Osnabrück, 49082, Osnabrück, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
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Abstract
Polyphosphoinositides (PPIn) are essential signaling phospholipids that make remarkable contributions to the identity of all cellular membranes and signaling cascades in mammalian cells. They exert regulatory control over membrane homeostasis via selective interactions with cellular proteins at the membrane–cytoplasm interface. This review article briefly summarizes our current understanding of the key roles that PPIn play in orchestrating and regulating crucial electrical and chemical signaling events in mammalian neurons and the significant neuro-pathophysiological conditions that arise following alterations in their metabolism.
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Affiliation(s)
- Eamonn James Dickson
- Department Physiology and Membrane Biology, University of California, Davis, CA, 95616, USA
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39
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Wang P, Hussey PJ. Plant ER-PM Contact Sites in Endocytosis and Autophagy: Does the Local Composition of Membrane Phospholipid Play a Role? FRONTIERS IN PLANT SCIENCE 2019; 10:23. [PMID: 30740118 PMCID: PMC6355705 DOI: 10.3389/fpls.2019.00023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 01/08/2019] [Indexed: 05/24/2023]
Affiliation(s)
- Pengwei Wang
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Patrick J. Hussey
- Department of Biosciences, Durham University, Durham, United Kingdom
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40
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Venditti R, Masone MC, Rega LR, Di Tullio G, Santoro M, Polishchuk E, Serrano IC, Olkkonen VM, Harada A, Medina DL, La Montagna R, De Matteis MA. The activity of Sac1 across ER-TGN contact sites requires the four-phosphate-adaptor-protein-1. J Cell Biol 2019; 218:783-797. [PMID: 30659099 PMCID: PMC6400556 DOI: 10.1083/jcb.201812021] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 12/14/2018] [Accepted: 12/19/2018] [Indexed: 01/05/2023] Open
Abstract
Venditti et al. identify FAPP1 as a new determinant of ER–trans-Golgi network contacts that interacts with the phosphoinositide phosphatase Sac1 and promotes its phosphatase activity. The results suggest that, by controlling PI4P levels, FAPP1 acts as a gatekeeper of cargo Golgi exit. Phosphatidylinositol-4-phosphate (PI4P), a phosphoinositide with key roles in the Golgi complex, is made by Golgi-associated phosphatidylinositol-4 kinases and consumed by the 4-phosphatase Sac1 that, instead, is an ER membrane protein. Here, we show that the contact sites between the ER and the TGN (ERTGoCS) provide a spatial setting suitable for Sac1 to dephosphorylate PI4P at the TGN. The ERTGoCS, though necessary, are not sufficient for the phosphatase activity of Sac1 on TGN PI4P, since this needs the phosphatidyl-four-phosphate-adaptor-protein-1 (FAPP1). FAPP1 localizes at ERTGoCS, interacts with Sac1, and promotes its in-trans phosphatase activity in vitro. We envision that FAPP1, acting as a PI4P detector and adaptor, positions Sac1 close to TGN domains with elevated PI4P concentrations allowing PI4P consumption. Indeed, FAPP1 depletion induces an increase in TGN PI4P that leads to increased secretion of selected cargoes (e.g., ApoB100), indicating that FAPP1, by controlling PI4P levels, acts as a gatekeeper of Golgi exit.
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Affiliation(s)
- Rossella Venditti
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.,Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Medical School, Naples, Italy
| | | | - Laura Rita Rega
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | - Michele Santoro
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | | | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland.,Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | | | - Diego L Medina
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy .,Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Medical School, Naples, Italy
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41
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Ionic stress enhances ER-PM connectivity via phosphoinositide-associated SYT1 contact site expansion in Arabidopsis. Proc Natl Acad Sci U S A 2019; 116:1420-1429. [PMID: 30610176 DOI: 10.1073/pnas.1818099116] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The interorganelle communication mediated by membrane contact sites (MCSs) is an evolutionary hallmark of eukaryotic cells. MCS connections enable the nonvesicular exchange of information between organelles and allow them to coordinate responses to changing cellular environments. In plants, the importance of MCS components in the responses to environmental stress has been widely established, but the molecular mechanisms regulating interorganelle connectivity during stress still remain opaque. In this report, we use the model plant Arabidopsis thaliana to show that ionic stress increases endoplasmic reticulum (ER)-plasma membrane (PM) connectivity by promoting the cortical expansion of synaptotagmin 1 (SYT1)-enriched ER-PM contact sites (S-EPCSs). We define differential roles for the cortical cytoskeleton in the regulation of S-EPCS dynamics and ER-PM connectivity, and we identify the accumulation of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] at the PM as a molecular signal associated with the ER-PM connectivity changes. Our study highlights the functional conservation of EPCS components and PM phosphoinositides as modulators of ER-PM connectivity in eukaryotes, and uncovers unique aspects of the spatiotemporal regulation of ER-PM connectivity in plants.
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42
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Liu L, Li J. Communications Between the Endoplasmic Reticulum and Other Organelles During Abiotic Stress Response in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:749. [PMID: 31249578 PMCID: PMC6582665 DOI: 10.3389/fpls.2019.00749] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 05/21/2019] [Indexed: 05/08/2023]
Abstract
To adapt to constantly changing environmental conditions, plants have evolved sophisticated tolerance mechanisms to integrate various stress signals and to coordinate plant growth and development. It is well known that inter-organellar communications play important roles in maintaining cellular homeostasis in response to environmental stresses. The endoplasmic reticulum (ER), extending throughout the cytoplasm of eukaryotic cells, is a central organelle involved in lipid metabolism, Ca2+ homeostasis, and synthesis and folding of secretory and transmembrane proteins crucial to perceive and transduce environmental signals. The ER communicates with the nucleus via the highly conserved unfolded protein response pathway to mitigate ER stress. Importantly, recent studies have revealed that the dynamic ER network physically interacts with other intracellular organelles and endomembrane compartments, such as the Golgi complex, mitochondria, chloroplast, peroxisome, vacuole, and the plasma membrane, through multiple membrane contact sites between closely apposed organelles. In this review, we will discuss the signaling and metabolite exchanges between the ER and other organelles during abiotic stress responses in plants as well as the ER-organelle membrane contact sites and their associated tethering complexes.
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Affiliation(s)
- Linchuan Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Jianming Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
- *Correspondence: Jianming Li, ;
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43
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Giovani PA, Salmon CR, Martins L, Leme AFP, Puppin-Rontani RM, Mofatto LS, Nociti FH, Kantovitz KR. Membrane proteome characterization of periodontal ligament cell sets from deciduous and permanent teeth. J Periodontol 2018; 90:775-787. [PMID: 30499115 DOI: 10.1002/jper.18-0217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 09/24/2018] [Accepted: 09/30/2018] [Indexed: 01/09/2023]
Abstract
BACKGROUND Physiological roles for the periodontal ligament (PDL) include tooth eruption and anchorage, force absorption, and provision of proprioceptive information. Despite the advances in understanding the biology of PDL cells, there is a lack of information regarding the molecular signature of deciduous (DecPDL) and permanent (PermPDL) PDL tissues. Thus, the present study was designed to characterize the membrane proteome of DecPDL and PermPDL cells. METHODS Primary PDL cells were obtained (n = 6) and a label-free quantitative proteome of cell membrane-enriched components was performed. Proteome findings were validated by quantitative polymerase chain reaction and Western blot assays in fresh human tissues (n = 8) and primary cell cultures (n = 6). In addition, confocal microscopy was used to verify the expression of target factors in the PDL cell cultures. RESULTS Comparative gene ontology enrichment analysis evidenced that most stickling differences involved "endomembrane system" (PICALM, STX4, and LRP10), "hydrolase activity" (NCSTN and XRCC6), "protein binding" (PICALM, STX4, GPNMB, VASP, extended-synaptotagmin 2 [ESYT2], and leucine-rich repeat containing 15 [LRRC15]), and "isomerase activity" (FKBP8). Data are available via ProteomeXchange with identifier PXD010226. At the transcript level, high PICALM in DecPDL and ESYT2 and LRRC15 in PermPDL were confirmed in fresh PDL tissues. Furthermore, Western blot analysis confirmed increased levels of PICALM, LRRC15, and ESYT2 in cells and/or fresh tissues, and confocal microscopy confirmed the trends for PICALM and LRRC15 expression in PDL cells. CONCLUSION We report the first comprehensive characterization of the membrane protein machinery of DecPDL and PermPDL cells, and together, we identified a distinct molecular signature for these cell populations, including unique proteins for DecPDL and PermPDL.
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Affiliation(s)
- Priscila A Giovani
- Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas, Campinas, São Paulo, Brazil
| | - Cristiane R Salmon
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil
| | - Luciane Martins
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil
| | - Adriana F P Leme
- Brazilian Biosciences National Laboratory, LNBio, CNPEM, Campinas, São Paulo, Brazil
| | - Regina M Puppin-Rontani
- Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas, Campinas, São Paulo, Brazil
| | - Luciana S Mofatto
- Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Piracicaba, São Paulo, Brazil
| | - Francisco H Nociti
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil
| | - Kamila R Kantovitz
- Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas, Campinas, São Paulo, Brazil.,Department of Dental Materials, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil
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44
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Kirmiz M, Palacio S, Thapa P, King AN, Sack JT, Trimmer JS. Remodeling neuronal ER-PM junctions is a conserved nonconducting function of Kv2 plasma membrane ion channels. Mol Biol Cell 2018; 29:2410-2432. [PMID: 30091655 PMCID: PMC6233057 DOI: 10.1091/mbc.e18-05-0337] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The endoplasmic reticulum (ER) and plasma membrane (PM) form junctions crucial to ion and lipid signaling and homeostasis. The Kv2.1 ion channel is localized at ER–PM junctions in brain neurons and is unique among PM proteins in its ability to remodel these specialized membrane contact sites. Here, we show that this function is conserved between Kv2.1 and Kv2.2, which differ in their biophysical properties, modulation, and cellular expression. Kv2.2 ER–PM junctions are present at sites deficient in the actin cytoskeleton, and disruption of the actin cytoskeleton affects their spatial organization. Kv2.2-containing ER–PM junctions overlap with those formed by canonical ER–PM tethers. The ability of Kv2 channels to remodel ER–PM junctions is unchanged by point mutations that eliminate their ion conduction but eliminated by point mutations within the Kv2-specific proximal restriction and clustering (PRC) domain that do not impact their ion channel function. The highly conserved PRC domain is sufficient to transfer the ER–PM junction–remodeling function to another PM protein. Last, brain neurons in Kv2 double-knockout mice have altered ER–PM junctions. Together, these findings demonstrate a conserved in vivo function for Kv2 family members in remodeling neuronal ER–PM junctions that is distinct from their canonical role as ion-conducting channels shaping neuronal excitability.
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Affiliation(s)
- Michael Kirmiz
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616
| | - Stephanie Palacio
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616
| | - Parashar Thapa
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616
| | - Anna N King
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616
| | - Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616.,Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - James S Trimmer
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616.,Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616
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45
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Stefan CJ. Building ER-PM contacts: keeping calm and ready on alarm. Curr Opin Cell Biol 2018; 53:1-8. [DOI: 10.1016/j.ceb.2018.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 03/20/2018] [Accepted: 03/22/2018] [Indexed: 11/28/2022]
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46
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Identification of VAPA and VAPB as Kv2 Channel-Interacting Proteins Defining Endoplasmic Reticulum-Plasma Membrane Junctions in Mammalian Brain Neurons. J Neurosci 2018; 38:7562-7584. [PMID: 30012696 DOI: 10.1523/jneurosci.0893-18.2018] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/01/2018] [Accepted: 07/07/2018] [Indexed: 11/21/2022] Open
Abstract
Membrane contacts between endoplasmic reticulum (ER) and plasma membrane (PM), or ER-PM junctions, are ubiquitous in eukaryotic cells and are platforms for lipid and calcium signaling and homeostasis. Recent studies have revealed proteins crucial to the formation and function of ER-PM junctions in non-neuronal cells, but little is known of the ER-PM junctions prominent in aspiny regions of mammalian brain neurons. The Kv2.1 voltage-gated potassium channel is abundantly clustered at ER-PM junctions in brain neurons and is the first PM protein that functions to organize ER-PM junctions. However, the molecular mechanism whereby Kv2.1 localizes to and remodels these junctions is unknown. We used affinity immunopurification and mass spectrometry-based proteomics on brain samples from male and female WT and Kv2.1 KO mice and identified the resident ER vesicle-associated membrane protein-associated proteins isoforms A and B (VAPA and VAPB) as prominent Kv2.1-associated proteins. Coexpression with Kv2.1 or its paralog Kv2.2 was sufficient to recruit VAPs to ER-PM junctions. Multiplex immunolabeling revealed colocalization of Kv2.1 and Kv2.2 with endogenous VAPs at ER-PM junctions in brain neurons from male and female mice in situ and in cultured rat hippocampal neurons, and KO of VAPA in mammalian cells reduces Kv2.1 clustering. The association of VAPA with Kv2.1 relies on a "two phenylalanines in an acidic tract" (FFAT) binding domain on VAPA and a noncanonical phosphorylation-dependent FFAT motif comprising the Kv2-specific clustering or PRC motif. These results suggest that Kv2.1 localizes to and organizes neuronal ER-PM junctions through an interaction with VAPs.SIGNIFICANCE STATEMENT Our study identified the endoplasmic reticulum (ER) proteins vesicle-associated membrane protein-associated proteins isoforms A and B (VAPA and VAPB) as proteins copurifying with the plasma membrane (PM) Kv2.1 ion channel. We found that expression of Kv2.1 recruits VAPs to ER-PM junctions, specialized membrane contact sites crucial to distinct aspects of cell function. We found endogenous VAPs at Kv2.1-mediated ER-PM junctions in brain neurons and other mammalian cells and that knocking out VAPA expression disrupts Kv2.1 clustering. We identified domains of VAPs and Kv2.1 necessary and sufficient for their association at ER-PM junctions. Our study suggests that Kv2.1 expression in the PM can affect ER-PM junctions via its phosphorylation-dependent association to ER-localized VAPA and VAPB.
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47
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Kv2 potassium channels form endoplasmic reticulum/plasma membrane junctions via interaction with VAPA and VAPB. Proc Natl Acad Sci U S A 2018; 115:E7331-E7340. [PMID: 29941597 DOI: 10.1073/pnas.1805757115] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kv2.1 exhibits two distinct forms of localization patterns on the neuronal plasma membrane: One population is freely diffusive and regulates electrical activity via voltage-dependent K+ conductance while a second one localizes to micrometer-sized clusters that contain densely packed, but nonconducting, channels. We have previously established that these clusters represent endoplasmic reticulum/plasma membrane (ER/PM) junctions that function as membrane trafficking hubs and that Kv2.1 plays a structural role in forming these membrane contact sites in both primary neuronal cultures and transfected HEK cells. Clustering and the formation of ER/PM contacts are regulated by phosphorylation within the channel C terminus, offering cells fast, dynamic control over the physical relationship between the cortical ER and PM. The present study addresses the mechanisms by which Kv2.1 and the related Kv2.2 channel interact with the ER membrane. Using proximity-based biotinylation techniques in transfected HEK cells we identified ER VAMP-associated proteins (VAPs) as potential Kv2.1 interactors. Confirmation that Kv2.1 and -2.2 bind VAPA and VAPB employed colocalization/redistribution, siRNA knockdown, and Förster resonance energy transfer (FRET)-based assays. CD4 chimeras containing sequence from the Kv2.1 C terminus were used to identify a noncanonical VAP-binding motif. VAPs were first identified as proteins required for neurotransmitter release in Aplysia and are now known to be abundant scaffolding proteins involved in membrane contact site formation throughout the ER. The VAP interactome includes AKAPs, kinases, membrane trafficking machinery, and proteins regulating nonvesicular lipid transport from the ER to the PM. Therefore, the Kv2-induced VAP concentration at ER/PM contact sites is predicted to have wide-ranging effects on neuronal cell biology.
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48
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Phospholipid transport protein function at organelle contact sites. Curr Opin Cell Biol 2018; 53:52-60. [PMID: 29859321 PMCID: PMC6141807 DOI: 10.1016/j.ceb.2018.04.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/12/2018] [Accepted: 04/29/2018] [Indexed: 11/21/2022]
Abstract
Phospholipids are synthesized at the endoplasmic reticulum (ER), the largest membrane bound organelle that forms membrane contact sites (MCS) with almost every other organelle. MCS are locations at which the membrane es of two organelles are closely positioned to provide a microenvironment where proteins in one membrane can interact with the opposite membrane. Thus, MCS provide an ideal location at which lipid transfer proteins (LTPs) can achieve the efficient transfer of individual classes of lipids from the ER to other organelles via non-vesicular transport. Here we provide an overview of emerging findings on the localization and biochemical activity of LTPs at MCS between the ER and other cellular membranes. The localization of LTPs at MCS offers an elegant cell biological solution to tune local lipid composition to ongoing cell physiology.
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49
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Quon E, Sere YY, Chauhan N, Johansen J, Sullivan DP, Dittman JS, Rice WJ, Chan RB, Di Paolo G, Beh CT, Menon AK. Endoplasmic reticulum-plasma membrane contact sites integrate sterol and phospholipid regulation. PLoS Biol 2018; 16:e2003864. [PMID: 29782498 PMCID: PMC5983861 DOI: 10.1371/journal.pbio.2003864] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 06/01/2018] [Accepted: 04/20/2018] [Indexed: 01/21/2023] Open
Abstract
Tether proteins attach the endoplasmic reticulum (ER) to other cellular membranes, thereby creating contact sites that are proposed to form platforms for regulating lipid homeostasis and facilitating non-vesicular lipid exchange. Sterols are synthesized in the ER and transported by non-vesicular mechanisms to the plasma membrane (PM), where they represent almost half of all PM lipids and contribute critically to the barrier function of the PM. To determine whether contact sites are important for both sterol exchange between the ER and PM and intermembrane regulation of lipid metabolism, we generated Δ-super-tether (Δ-s-tether) yeast cells that lack six previously identified tethering proteins (yeast extended synatotagmin [E-Syt], vesicle-associated membrane protein [VAMP]-associated protein [VAP], and TMEM16-anoctamin homologues) as well as the presumptive tether Ice2. Despite the lack of ER-PM contacts in these cells, ER-PM sterol exchange is robust, indicating that the sterol transport machinery is either absent from or not uniquely located at contact sites. Unexpectedly, we found that the transport of exogenously supplied sterol to the ER occurs more slowly in Δ-s-tether cells than in wild-type (WT) cells. We pinpointed this defect to changes in sterol organization and transbilayer movement within the PM bilayer caused by phospholipid dysregulation, evinced by changes in the abundance and organization of PM lipids. Indeed, deletion of either OSH4, which encodes a sterol/phosphatidylinositol-4-phosphate (PI4P) exchange protein, or SAC1, which encodes a PI4P phosphatase, caused synthetic lethality in Δ-s-tether cells due to disruptions in redundant PI4P and phospholipid regulatory pathways. The growth defect of Δ-s-tether cells was rescued with an artificial "ER-PM staple," a tether assembled from unrelated non-yeast protein domains, indicating that endogenous tether proteins have nonspecific bridging functions. Finally, we discovered that sterols play a role in regulating ER-PM contact site formation. In sterol-depleted cells, levels of the yeast E-Syt tether Tcb3 were induced and ER-PM contact increased dramatically. These results support a model in which ER-PM contact sites provide a nexus for coordinating the complex interrelationship between sterols, sphingolipids, and phospholipids that maintain PM composition and integrity. Almost half of the inner surface area of the yeast plasma membrane (PM) is covered with closely associated cortical endoplasmic reticulum (ER). In yeast and human cells, it has been proposed that ER-anchored tether proteins staple the ER to the PM, creating membrane contact sites at which lipid transport between the ER and PM and membrane lipid synthesis are coordinately regulated, but the potential mechanisms are unclear. Here, we test this idea by creating yeast cells that lack all ER-PM tethers. We find that whereas the bidirectional transport of sterols between the ER and PM is unaffected in these cells, sterols within the PM are disorganized due to disruptions in phospholipid biosynthesis that alter PM lipid composition. In particular, we show that phosphatidylinositol-4-phosphate, a phospholipid needed for intracellular signaling and membrane trafficking, accumulates within the PM. Some of these defects can be rescued by reinstating membrane contacts via expression of an artificial tether. However, correction is also achieved without the creation of contacts by supplementing the growth medium with a precursor of membrane phospholipids. Based on these results, we propose that ER-PM contacts do not play a major role as physical conduits for lipid exchange but rather serve as regulatory interfaces to integrate lipid synthesis pathways.
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Affiliation(s)
- Evan Quon
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Yves Y. Sere
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
| | - Neha Chauhan
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
| | - Jesper Johansen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - David P. Sullivan
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
| | - Jeremy S. Dittman
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
| | - William J. Rice
- Simons Electron Microscopy Center at the New York Structural Biology Center, New York, New York, United States of America
| | - Robin B. Chan
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
- Denali Therapeutics, South San Francisco, California, United States of America
| | - Christopher T. Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail: (AKM); (CTB)
| | - Anant K. Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (AKM); (CTB)
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50
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Antonny B, Bigay J, Mesmin B. The Oxysterol-Binding Protein Cycle: Burning Off PI(4)P to Transport Cholesterol. Annu Rev Biochem 2018; 87:809-837. [PMID: 29596003 DOI: 10.1146/annurev-biochem-061516-044924] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To maintain an asymmetric distribution of ions across membranes, protein pumps displace ions against their concentration gradient by using chemical energy. Here, we describe a functionally analogous but topologically opposite process that applies to the lipid transfer protein (LTP) oxysterol-binding protein (OSBP). This multidomain protein exchanges cholesterol for the phosphoinositide phosphatidylinositol 4-phosphate [PI(4)P] between two apposed membranes. Because of the subsequent hydrolysis of PI(4)P, this counterexchange is irreversible and contributes to the establishment of a cholesterol gradient along organelles of the secretory pathway. The facts that some natural anti-cancer molecules block OSBP and that many viruses hijack the OSBP cycle for the formation of intracellular replication organelles highlight the importance and potency of OSBP-mediated lipid exchange. The architecture of some LTPs is similar to that of OSBP, suggesting that the principles of the OSBP cycle-burning PI(4)P for the vectorial transfer of another lipid-might be general.
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Affiliation(s)
- Bruno Antonny
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS UMR 7275, Université Côte d'Azur, 06560 Valbonne, France;
| | - Joëlle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS UMR 7275, Université Côte d'Azur, 06560 Valbonne, France;
| | - Bruno Mesmin
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS UMR 7275, Université Côte d'Azur, 06560 Valbonne, France;
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