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Abstract
All known eukaryotes require copper for their development and survival. The essentiality of copper reflects its widespread use as a co-factor in conserved enzymes that catalyze biochemical reactions critical to energy production, free radical detoxification, collagen deposition, neurotransmitter biosynthesis and iron homeostasis. However, the prioritized use of copper poses an organism with a considerable challenge because, in its unbound form, copper can potentiate free radical production and displace iron-sulphur clusters to disrupt protein function. Protective mechanisms therefore evolved to mitigate this challenge and tightly regulate the acquisition, trafficking and storage of copper such that the metal ion is rarely found in its free form in the cell. Findings by a number of groups over the last ten years emphasize that this regulatory framework forms the foundation of a system that is capable of monitoring copper status and reprioritizing copper usage at both the cellular and systemic levels of organization. While the identification of relevant molecular mechanisms and signaling pathways has proven to be difficult and remains a barrier to our full understanding of the regulation of copper homeostasis, mounting evidence points to the mitochondrion as a pivotal hub in this regard in both healthy and diseased states. Here, we review our current understanding of copper handling pathways contained within the organelle and consider plausible mechanisms that may serve to functionally couple their activity to that of other cellular copper handling machinery to maintain copper homeostasis.
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Affiliation(s)
- Zakery N. Baker
- Department of Biochemistry, University of Saskatchewan, Saskatoon, SK Canada S7N 5E5
| | - Paul A. Cobine
- Department of Biological Sciences, Auburn University, Auburn, Alabama 36849, USA
| | - Scot C. Leary
- Department of Biochemistry, University of Saskatchewan, Saskatoon, SK Canada S7N 5E5
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Mahadevan V, Khademullah CS, Dargaei Z, Chevrier J, Uvarov P, Kwan J, Bagshaw RD, Pawson T, Emili A, De Koninck Y, Anggono V, Airaksinen M, Woodin MA. Native KCC2 interactome reveals PACSIN1 as a critical regulator of synaptic inhibition. eLife 2017; 6:e28270. [PMID: 29028184 PMCID: PMC5640428 DOI: 10.7554/elife.28270] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/08/2017] [Indexed: 01/01/2023] Open
Abstract
KCC2 is a neuron-specific K+-Cl- cotransporter essential for establishing the Cl- gradient required for hyperpolarizing inhibition in the central nervous system (CNS). KCC2 is highly localized to excitatory synapses where it regulates spine morphogenesis and AMPA receptor confinement. Aberrant KCC2 function contributes to human neurological disorders including epilepsy and neuropathic pain. Using functional proteomics, we identified the KCC2-interactome in the mouse brain to determine KCC2-protein interactions that regulate KCC2 function. Our analysis revealed that KCC2 interacts with diverse proteins, and its most predominant interactors play important roles in postsynaptic receptor recycling. The most abundant KCC2 interactor is a neuronal endocytic regulatory protein termed PACSIN1 (SYNDAPIN1). We verified the PACSIN1-KCC2 interaction biochemically and demonstrated that shRNA knockdown of PACSIN1 in hippocampal neurons increases KCC2 expression and hyperpolarizes the reversal potential for Cl-. Overall, our global native-KCC2 interactome and subsequent characterization revealed PACSIN1 as a novel and potent negative regulator of KCC2.
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Affiliation(s)
- Vivek Mahadevan
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | | | - Zahra Dargaei
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Jonah Chevrier
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Pavel Uvarov
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Julian Kwan
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Richard D Bagshaw
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Tony Pawson
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Andrew Emili
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de QuébecQuébecCanada
- Department of Psychiatry and NeuroscienceUniversité LavalQuébecCanada
| | - Victor Anggono
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia ResearchThe University of QueenslandBrisbaneAustralia
| | - Matti Airaksinen
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Melanie A Woodin
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
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53
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Frappaolo A, Sechi S, Kumagai T, Robinson S, Fraschini R, Karimpour-Ghahnavieh A, Belloni G, Piergentili R, Tiemeyer KH, Tiemeyer M, Giansanti MG. COG7 deficiency in Drosophila generates multifaceted developmental, behavioral and protein glycosylation phenotypes. J Cell Sci 2017; 130:3637-3649. [PMID: 28883096 DOI: 10.1242/jcs.209049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 09/04/2017] [Indexed: 12/14/2022] Open
Abstract
Congenital disorders of glycosylation (CDG) comprise a family of human multisystemic diseases caused by recessive mutations in genes required for protein N-glycosylation. More than 100 distinct forms of CDGs have been identified and most of them cause severe neurological impairment. The Conserved Oligomeric Golgi (COG) complex mediates tethering of vesicles carrying glycosylation enzymes across the Golgi cisternae. Mutations affecting human COG1, COG2 and COG4-COG8 cause monogenic forms of inherited, autosomal recessive CDGs. We have generated a Drosophila COG7-CDG model that closely parallels the pathological characteristics of COG7-CDG patients, including pronounced neuromotor defects associated with altered N-glycome profiles. Consistent with these alterations, larval neuromuscular junctions of Cog7 mutants exhibit a significant reduction in bouton numbers. We demonstrate that the COG complex cooperates with Rab1 and Golgi phosphoprotein 3 to regulate Golgi trafficking and that overexpression of Rab1 can rescue the cytokinesis and locomotor defects associated with loss of Cog7. Our results suggest that the Drosophila COG7-CDG model can be used to test novel potential therapeutic strategies by modulating trafficking pathways.
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Affiliation(s)
- Anna Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Stefano Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Tadahiro Kumagai
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Rd., Athens, GA 30602, USA
| | - Sarah Robinson
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Rd., Athens, GA 30602, USA
| | - Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Università degli studi di Milano Bicocca, 20126 Milano, Italy
| | - Angela Karimpour-Ghahnavieh
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Giorgio Belloni
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Roberto Piergentili
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Piazzale A. Moro 5, 00185 Roma, Italy
| | - Katherine H Tiemeyer
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Rd., Athens, GA 30602, USA
| | - Michael Tiemeyer
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Rd., Athens, GA 30602, USA .,Department of Biochemistry and Molecular Biology, The University of Georgia, B122 Life Sciences Building, Athens, GA 30602, USA
| | - Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Biologia e Biotecnologie, Università Sapienza di Roma, Roma, Piazzale A. Moro 5, 00185 Roma, Italy
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54
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Climer LK, Hendrix RD, Lupashin VV. Conserved Oligomeric Golgi and Neuronal Vesicular Trafficking. Handb Exp Pharmacol 2017; 245:227-247. [PMID: 29063274 DOI: 10.1007/164_2017_65] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The conserved oligomeric Golgi (COG) complex is an evolutionary conserved multi-subunit vesicle tethering complex essential for the majority of Golgi apparatus functions: protein and lipid glycosylation and protein sorting. COG is present in neuronal cells, but the repertoire of COG function in different Golgi-like compartments is an enigma. Defects in COG subunits cause alteration of Golgi morphology, protein trafficking, and glycosylation resulting in human congenital disorders of glycosylation (CDG) type II. In this review we summarize and critically analyze recent advances in the function of Golgi and Golgi-like compartments in neuronal cells and functions and dysfunctions of the COG complex and its partner proteins.
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Affiliation(s)
- Leslie K Climer
- College of Medicine, Physiology and Biophysics, UAMS, Little Rock, AR, USA
| | - Rachel D Hendrix
- College of Medicine, Neurobiology and Developmental Sciences, UAMS, Little Rock, AR, USA
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