1
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Seitz C, Deveci İ, McCammon JA. Glycosylation and Crowded Membrane Effects on Influenza Neuraminidase Stability and Dynamics. J Phys Chem Lett 2023; 14:9926-9934. [PMID: 37903229 PMCID: PMC10641874 DOI: 10.1021/acs.jpclett.3c02524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 10/18/2023] [Accepted: 10/24/2023] [Indexed: 11/01/2023]
Abstract
All protein simulations are conducted with varying degrees of simplification, oftentimes with unknown ramifications about how these simplifications affect the interpretability of the results. In this work, we investigated how protein glycosylation and lateral crowding effects modulate an array of properties characterizing the stability and dynamics of influenza neuraminidase. We constructed three systems: (1) glycosylated neuraminidase in a whole virion (i.e., crowded membrane) environment, (2) glycosylated neuraminidase in its own lipid bilayer, and (3) unglycosylated neuraminidase in its own lipid bilayer. We saw that glycans tend to stabilize the protein structure and reduce its conformational flexibility while restricting the solvent movement. Conversely, a crowded membrane environment encouraged exploration of the free energy landscape and a large-scale conformational change, while making the protein structure more compact. Understanding these effects informs what factors one must consider in attempting to recapture the desired level of physical accuracy.
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Affiliation(s)
- Christian Seitz
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
| | - İlker Deveci
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
| | - J. Andrew McCammon
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
- Department
of Pharmacology, University of California,
San Diego, La Jolla, California 92093, United States
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2
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Seitz C, Deveci İ, McCammon JA. Glycosylation and Crowded Membrane Effects on Influenza Neuraminidase Stability and Dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.10.556910. [PMID: 37745347 PMCID: PMC10515755 DOI: 10.1101/2023.09.10.556910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
All protein simulations are conducted with varying degrees of simplifications, oftentimes with unknown ramifications on how these simplifications affect the interpretability of the results. In this work we investigated how protein glycosylation and lateral crowding effects modulate an array of properties characterizing the stability and dynamics of influenza neuraminidase. We constructed three systems: 1) Glycosylated neuraminidase in a whole virion (i.e. crowded membrane) environment 2) Glycosylated neuraminidase in its own lipid bilayer 3) Unglycosylated neuraminidase in its own lipid bilayer. We saw that glycans tend to stabilize the protein structure and reduce its conformational flexibility while restricting solvent movement. Conversely, a crowded membrane environment encouraged exploration of the free energy landscape and a large scale conformational change while making the protein structure more compact. Understanding these effects informs what factors one must consider while attempting to recapture the desired level of physical accuracy.
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Affiliation(s)
- Christian Seitz
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
| | - İlker Deveci
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
| | - J. Andrew McCammon
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
- Department of Pharmacology, University of California, San Diego, La Jolla, California
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3
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Esmail S, Manolson MF. Advances in understanding N-glycosylation structure, function, and regulation in health and disease. Eur J Cell Biol 2021; 100:151186. [PMID: 34839178 DOI: 10.1016/j.ejcb.2021.151186] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/14/2021] [Accepted: 11/18/2021] [Indexed: 01/17/2023] Open
Abstract
N-linked glycosylation is a post-translational modification crucial for membrane protein folding, stability and other cellular functions. Alteration of membrane protein N-glycans is implicated in wide range of pathological conditions including cancer metastasis, chronic inflammatory diseases, and viral pathogenesis. Even though the roles of N-glycans have been studied extensively, our knowledge of their mechanisms remains unclear due to the lack of detailed structural analysis of the N-glycome. Mapping the N-glycome landscape will open new avenues to explore disease mechanisms and identify novel therapeutic targets. This review discusses the diverse structure of N-linked glycans, the function and regulation of N-glycosylation in health and disease, and ends with a focus on recent approaches to target N-glycans in rheumatoid arthritis and cancer metastasis.
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Affiliation(s)
- Sally Esmail
- Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6, Canada.
| | - Morris F Manolson
- Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6, Canada
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4
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Oot RA, Yao Y, Manolson MF, Wilkens S. Purification of active human vacuolar H +-ATPase in native lipid-containing nanodiscs. J Biol Chem 2021; 297:100964. [PMID: 34270960 PMCID: PMC8353480 DOI: 10.1016/j.jbc.2021.100964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/07/2021] [Accepted: 07/12/2021] [Indexed: 12/26/2022] Open
Abstract
Vacuolar H+-ATPases (V-ATPases) are large, multisubunit proton pumps that acidify the lumen of organelles in virtually every eukaryotic cell and in specialized acid-secreting animal cells, the enzyme pumps protons into the extracellular space. In higher organisms, most of the subunits are expressed as multiple isoforms, with some enriched in specific compartments or tissues and others expressed ubiquitously. In mammals, subunit a is expressed as four isoforms (a1-4) that target the enzyme to distinct biological membranes. Mutations in a isoforms are known to give rise to tissue-specific disease, and some a isoforms are upregulated and mislocalized to the plasma membrane in invasive cancers. However, isoform complexity and low abundance greatly complicate purification of active human V-ATPase, a prerequisite for developing isoform-specific therapeutics. Here, we report the purification of an active human V-ATPase in native lipid nanodiscs from a cell line stably expressing affinity-tagged a isoform 4 (a4). We find that exogenous expression of this single subunit in HEK293F cells permits assembly of a functional V-ATPase by incorporation of endogenous subunits. The ATPase activity of the preparation is >95% sensitive to concanamycin A, indicating that the lipid nanodisc-reconstituted enzyme is functionally coupled. Moreover, this strategy permits purification of the enzyme’s isolated membrane subcomplex together with biosynthetic assembly factors coiled-coil domain–containing protein 115, transmembrane protein 199, and vacuolar H+-ATPase assembly integral membrane protein 21. Our work thus lays the groundwork for biochemical characterization of active human V-ATPase in an a subunit isoform-specific manner and establishes a platform for the study of the assembly and regulation of the human holoenzyme.
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Affiliation(s)
- Rebecca A Oot
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Yeqi Yao
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Morris F Manolson
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA.
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5
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Wang L, Wu D, Robinson CV, Wu H, Fu TM. Structures of a Complete Human V-ATPase Reveal Mechanisms of Its Assembly. Mol Cell 2020; 80:501-511.e3. [PMID: 33065002 PMCID: PMC7655608 DOI: 10.1016/j.molcel.2020.09.029] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 12/22/2022]
Abstract
Vesicular- or vacuolar-type adenosine triphosphatases (V-ATPases) are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer. They play important roles in acidification of intracellular vesicles, organelles, and the extracellular milieu in eukaryotes. Here, we report cryoelectron microscopy structures of human V-ATPase in three rotational states at up to 2.9-Å resolution. Aided by mass spectrometry, we build all known protein subunits with associated N-linked glycans and identify glycolipids and phospholipids in the Vo complex. We define ATP6AP1 as a structural hub for Vo complex assembly because it connects to multiple Vo subunits and phospholipids in the c-ring. The glycolipids and the glycosylated Vo subunits form a luminal glycan coat critical for V-ATPase folding, localization, and stability. This study identifies mechanisms of V-ATPase assembly and biogenesis that rely on the integrated roles of ATP6AP1, glycans, and lipids.
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Affiliation(s)
- Longfei Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
| | - Di Wu
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
| | - Tian-Min Fu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA.
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6
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Boll I, Jensen P, Schwämmle V, Larsen MR. Depolarization-dependent Induction of Site-specific Changes in Sialylation on N-linked Glycoproteins in Rat Nerve Terminals. Mol Cell Proteomics 2020; 19:1418-1435. [PMID: 32518069 PMCID: PMC8143646 DOI: 10.1074/mcp.ra119.001896] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 06/08/2020] [Indexed: 12/11/2022] Open
Abstract
Synaptic transmission leading to release of neurotransmitters in the nervous system is a fast and highly dynamic process. Previously, protein interaction and phosphorylation have been thought to be the main regulators of synaptic transmission. Here we show that sialylation of N-linked glycosylation is a novel potential modulator of neurotransmitter release mechanisms by investigating depolarization-dependent changes of formerly sialylated N-linked glycopeptides. We suggest that negatively charged sialic acids can be modulated, similarly to phosphorylation, by the action of sialyltransferases and sialidases thereby changing local structure and function of membrane glycoproteins. We characterized site-specific alteration in sialylation on N-linked glycoproteins in isolated rat nerve terminals after brief depolarization using quantitative sialiomics. We identified 1965 formerly sialylated N-linked glycosites in synaptic proteins and found that the abundances of 430 glycosites changed after 5 s depolarization. We observed changes on essential synaptic proteins such as synaptic vesicle proteins, ion channels and transporters, neurotransmitter receptors and cell adhesion molecules. This study is to our knowledge the first to describe ultra-fast site-specific modulation of the sialiome after brief stimulation of a biological system.
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Affiliation(s)
- Inga Boll
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Pia Jensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Veit Schwämmle
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
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7
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Linders PTA, Peters E, ter Beest M, Lefeber DJ, van den Bogaart G. Sugary Logistics Gone Wrong: Membrane Trafficking and Congenital Disorders of Glycosylation. Int J Mol Sci 2020; 21:E4654. [PMID: 32629928 PMCID: PMC7369703 DOI: 10.3390/ijms21134654] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 02/07/2023] Open
Abstract
Glycosylation is an important post-translational modification for both intracellular and secreted proteins. For glycosylation to occur, cargo must be transported after synthesis through the different compartments of the Golgi apparatus where distinct monosaccharides are sequentially bound and trimmed, resulting in increasingly complex branched glycan structures. Of utmost importance for this process is the intraorganellar environment of the Golgi. Each Golgi compartment has a distinct pH, which is maintained by the vacuolar H+-ATPase (V-ATPase). Moreover, tethering factors such as Golgins and the conserved oligomeric Golgi (COG) complex, in concert with coatomer (COPI) and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion, efficiently deliver glycosylation enzymes to the right Golgi compartment. Together, these factors maintain intra-Golgi trafficking of proteins involved in glycosylation and thereby enable proper glycosylation. However, pathogenic mutations in these factors can cause defective glycosylation and lead to diseases with a wide variety of symptoms such as liver dysfunction and skin and bone disorders. Collectively, this group of disorders is known as congenital disorders of glycosylation (CDG). Recent technological advances have enabled the robust identification of novel CDGs related to membrane trafficking components. In this review, we highlight differences and similarities between membrane trafficking-related CDGs.
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Affiliation(s)
- Peter T. A. Linders
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
| | - Ella Peters
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
| | - Martin ter Beest
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
| | - Dirk J. Lefeber
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands
| | - Geert van den Bogaart
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
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8
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Kanaki N, Matsuda A, Dejima K, Murata D, Nomura KH, Ohkura T, Gengyo-Ando K, Yoshina S, Mitani S, Nomura K. UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase is indispensable for oogenesis, oocyte-to-embryo transition, and larval development of the nematode Caenorhabditis elegans. Glycobiology 2019; 29:163-178. [PMID: 30445613 DOI: 10.1093/glycob/cwy104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/09/2018] [Indexed: 12/13/2022] Open
Abstract
N-linked glycosylation of proteins is the most common post-translational modification of proteins. The enzyme UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase (DPAGT1) catalyses the first step of N-glycosylation, and DPAGT1 knockout is embryonic lethal in mice. In this study, we identified the sole orthologue (algn-7) of the human DPAGT1 in the nematode C. elegans. The gene activity was disrupted by RNAi and deletion mutagenesis, which resulted in larval lethality, defects in oogenesis and oocyte-to-embryo transition. Endomitotic oocytes, abnormal fusion of pronuclei, abnormal AB cell rotation, disruption of permeation barriers of eggs, and abnormal expression of chitin and chitin synthase in oocytes and eggs were the typical phenotypes observed. The results indicate that N-glycosylation is indispensable for these processes. We further screened an N-glycosylated protein database of C. elegans, and identified 456 germline-expressed genes coding N-glycosylated proteins. By examining RNAi phenotypes, we identified five germline-expressed genes showing similar phenotypes to the algn-7 (RNAi) animals. They were ribo-1, stt-3, ptc-1, ptc-2, and vha-19. We identified known congenital disorders of glycosylation (CDG) genes (ribo-1 and stt-3) and a recently found CDG gene (vha-19). The results show that phenotype analyses using the nematode could be a powerful tool to detect new CDG candidate genes and their associated gene networks.
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Affiliation(s)
- Nanako Kanaki
- Department of Systems Life Sciences, Kyushu University Graduate School, Fukuoka, Japan
| | - Ayako Matsuda
- Department of Systems Life Sciences, Kyushu University Graduate School, Fukuoka, Japan
| | - Katsufumi Dejima
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.,Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Daisuke Murata
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Kazuko H Nomura
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Takashi Ohkura
- Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, Japan
| | - Keiko Gengyo-Ando
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Sawako Yoshina
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Kazuya Nomura
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
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9
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Zirngibl RA, Wang A, Yao Y, Manolson MF, Krueger J, Dupuis L, Mendoza-Londono R, Voronov I. Novel c.G630A TCIRG1 mutation causes aberrant splicing resulting in an unusually mild form of autosomal recessive osteopetrosis. J Cell Biochem 2019; 120:17180-17193. [PMID: 31111556 DOI: 10.1002/jcb.28979] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 03/19/2019] [Accepted: 03/22/2019] [Indexed: 12/22/2022]
Abstract
Autosomal recessive osteopetrosis (ARO) is a severe genetic bone disease characterized by high bone density due to mutations that affect formation or function of osteoclasts. Mutations in the a3 subunit of the vacuolar-type H+ -ATPase (encoded by T-cell immune regulator 1 [TCIRG1]) are responsible for ~50% of all ARO cases. We identified a novel TCIRG1 (c.G630A) mutation responsible for an unusually mild form of the disease. To characterize this mutation, osteoclasts were differentiated using peripheral blood monocytes from the patient (c.G630A/c.G630A), male sibling (+/+), unaffected female sibling (+/c.G630A), and unaffected parent (+/c.G630A). Osteoclast formation, bone-resorbing function, TCIRG1 protein, and mRNA expression levels were assessed. The c.G630A mutation did not affect osteoclast differentiation; however, bone-resorbing function was decreased. Both TCIRG1 protein and full-length TCIRG1 mRNA expression levels were also diminished in the affected patient's sample. The c.G630A mutation replaces the last nucleotide of exon 6 and may cause splicing defects. We analyzed the TCIRG1 splicing pattern between exons 4 to 8 and detected deletions of exons 5, 6, 7, and 5-6 (ΔE56). These deletions were only observed in c.G630A/c.G630A and +/c.G630A samples, but not in +/+ controls. Among these deletions, only ΔE56 maintained the reading frame and was predicted to generate an 85 kDa protein. Exons 5-6 encode an uncharacterized portion of the cytoplasmic N-terminal domain of a3, a domain not involved in proton translocation. To investigate the effect of ΔE56 on V-ATPase function, we transformed yeast with plasmids carrying full-length or truncated Vph1p, the yeast ortholog of a3. Both proteins were expressed; however, ΔE56-Vph1p transformed yeast failed to grow on Zn2+ -containing plates, a growth assay dependent on V-ATPase-mediated vacuolar acidification. In conclusion, our results show that the ΔE56 truncated protein is not functional, suggesting that the mild ARO phenotype observed in the patient is likely due to the residual full-length protein expression.
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Affiliation(s)
- Ralph A Zirngibl
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Wang
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Yeqi Yao
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Morris F Manolson
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Joerg Krueger
- Division of Hematology/Oncology and Blood and Marrow Transplant, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Lucie Dupuis
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Roberto Mendoza-Londono
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Irina Voronov
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
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10
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Gao X, Gao S, Guan Y, Huang L, Huang J, Lin L, Liu Y, Zhao H, Huang B, Yuan T, Liu Y, Liang D, Zhang Y, Ma X, Li L, Li J, Zhou D, Shi D, Xu L, Chen YH. Toll-like receptor 3 controls QT interval on the electrocardiogram by targeting the degradation of Kv4.2/4.3 channels in the endoplasmic reticulum. FASEB J 2019; 33:6197-6208. [PMID: 30758987 DOI: 10.1096/fj.201801464r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
TLRs have been proven to be essential mediators for the early innate immune response. Overactivation of TLR-mediated immune signaling promotes deterioration of cardiovascular diseases; however, the role of TLRs in the heart under physiologic conditions remains neglected. Here, we show that Tlr3 deficiency induced the endoplasmic reticulum (ER) retention of Kv4.2/4.3 proteins and consequent degradation via the ubiquitin-proteasome pathway. Knockout of Tlr3 resulted in a prolonged QT interval (the space between the start of the Q wave and the end of the T wave) in mice with no significant signs of inflammation and tissue abnormality in cardiac muscles. Prolongation of action potential duration resulted from the depression of transient outward potassium channel (Ito) currents in Tlr3-deficient ventricular myocytes mirrored the change in QT interval. Mechanistically, we found that Tlr3 was exclusively localized in the ER of cardiomyocytes where it interacted with Kv4.2/4.3 subunits of Ito channel. Thus, our data indicated that TLR3 directly regulates Ito channel protein dynamics to maintain cardiac repolarization, which may implicate a new molecular surveillance system for cardiac electrophysiological homeostasis.-Gao, X., Gao, S., Guan, Y., Huang, L., Huang, J., Lin, L., Liu, Y., Zhao, H., Huang, B., Yuan, T., Liu, Y., Liang, D., Zhang, Y., Ma, X., Li, L., Li, J., Zhou, D., Shi, D., Xu, L., Chen, Y.-H. Toll-like receptor 3 controls QT interval on the electrocardiogram by targeting the degradation of Kv4.2/4.3 channels in the endoplasmic reticulum.
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Affiliation(s)
- Xueting Gao
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Siyun Gao
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Guan
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Lin Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Jiale Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li Lin
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yuan Liu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Hong Zhao
- Department of Pediatrics, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Bijun Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Tianyou Yuan
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Liu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dandan Liang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yangyang Zhang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xiue Ma
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li Li
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Jun Li
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Daizhan Zhou
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dan Shi
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Liang Xu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi-Han Chen
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
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Duan X, Yang S, Zhang L, Yang T. V-ATPases and osteoclasts: ambiguous future of V-ATPases inhibitors in osteoporosis. Theranostics 2018; 8:5379-5399. [PMID: 30555553 PMCID: PMC6276090 DOI: 10.7150/thno.28391] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
Vacuolar ATPases (V-ATPases) play a critical role in regulating extracellular acidification of osteoclasts and bone resorption. The deficiencies of subunit a3 and d2 of V-ATPases result in increased bone density in humans and mice. One of the traditional drug design strategies in treating osteoporosis is the use of subunit a3 inhibitor. Recent findings connect subunits H and G1 with decreased bone density. Given the controversial effects of ATPase subunits on bone density, there is a critical need to review the subunits of V-ATPase in osteoclasts and their functions in regulating osteoclasts and bone remodeling. In this review, we comprehensively address the following areas: information about all V-ATPase subunits and their isoforms; summary of V-ATPase subunits associated with human genetic diseases; V-ATPase subunits and osteopetrosis/osteoporosis; screening of all V-ATPase subunits variants in GEFOS data and in-house data; spectrum of V-ATPase subunits during osteoclastogenesis; direct and indirect roles of subunits of V-ATPases in osteoclasts; V-ATPase-associated signaling pathways in osteoclasts; interactions among V-ATPase subunits in osteoclasts; osteoclast-specific V-ATPase inhibitors; perspective of future inhibitors or activators targeting V-ATPase subunits in the treatment of osteoporosis.
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Affiliation(s)
- Xiaohong Duan
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Department of Oral Biology, Clinic of Oral Rare and Genetic Diseases, School of Stomatology, the Fourth Military Medical University, 145 West Changle Road, Xi'an 710032, P. R. China
| | - Shaoqing Yang
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Department of Oral Biology, Clinic of Oral Rare and Genetic Diseases, School of Stomatology, the Fourth Military Medical University, 145 West Changle Road, Xi'an 710032, P. R. China
| | - Lei Zhang
- Center for Genetic Epidemiology and Genomics, School of Public Health, Medical College of Soochow University, 199 Renai Road, Suzhou, Jiangsu, P. R. China
| | - Tielin Yang
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, and Institute of Molecular Genetics, School of Life Science and Technology, Xi'an Jiaotong University, 28 West Xianning Road, Xi'an 710049, People's Republic of China
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Esmail S, Kartner N, Yao Y, Kim JW, Reithmeier RAF, Manolson MF. Molecular mechanisms of cutis laxa- and distal renal tubular acidosis-causing mutations in V-ATPase a subunits, ATP6V0A2 and ATP6V0A4. J Biol Chem 2018; 293:2787-2800. [PMID: 29311258 DOI: 10.1074/jbc.m117.818872] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/20/2017] [Indexed: 12/19/2022] Open
Abstract
The a subunit is the largest of 15 different subunits that make up the vacuolar H+-ATPase (V-ATPase) complex, where it functions in proton translocation. In mammals, this subunit has four paralogous isoforms, a1-a4, which may encode signals for targeting assembled V-ATPases to specific intracellular locations. Despite the functional importance of the a subunit, its structure remains controversial. By studying molecular mechanisms of human disease-causing missense mutations within a subunit isoforms, we may identify domains critical for V-ATPase targeting, activity and/or regulation. cDNA-encoded FLAG-tagged human wildtype ATP6V0A2 (a2) and ATP6V0A4 (a4) subunits and their mutants, a2P405L (causing cutis laxa), and a4R449H and a4G820R (causing renal tubular acidosis, dRTA), were transiently expressed in HEK 293 cells. N-Glycosylation was assessed using endoglycosidases, revealing that a2P405L, a4R449H, and a4G820R were fully N-glycosylated. Cycloheximide (CHX) chase assays revealed that a2P405L and a4R449H were unstable relative to wildtype. a4R449H was degraded predominantly in the proteasomal pathway, whereas a2P405L was degraded in both proteasomal and lysosomal pathways. Immunofluorescence studies disclosed retention in the endoplasmic reticulum and defective cell-surface expression of a4R449H and defective Golgi trafficking of a2P405L Co-immunoprecipitation studies revealed an increase in association of a4R449H with the V0 assembly factor VMA21, and a reduced association with the V1 sector subunit, ATP6V1B1 (B1). For a4G820R, where stability, degradation, and trafficking were relatively unaffected, 3D molecular modeling suggested that the mutation causes dRTA by blocking the proton pathway. This study provides critical information that may assist rational drug design to manage dRTA and cutis laxa.
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Affiliation(s)
- Sally Esmail
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | - Norbert Kartner
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | - Yeqi Yao
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | - Joo Wan Kim
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | | | - Morris F Manolson
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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13
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N-Glycosylation is required for FDNC5 stabilization and irisin secretion. Biochem J 2017; 474:3167-3177. [PMID: 28733331 DOI: 10.1042/bcj20170241] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/03/2017] [Accepted: 07/20/2017] [Indexed: 12/21/2022]
Abstract
Irisin, a myokine derived from the extracellular domain of FNDC5, has been shown to mediate thermogenesis of white adipose tissue. Biochemical data have shown that N-glycosylation of FNDC5 is unlikely to affect ligand or receptor activation of irisin. The N-glycosylation of FNDC5 remains poorly understood. In the present study, we analysed N-glycosylation sites of FNDC5 and found that two potential N-glycosylation sites (Asn36 and Asn81) could indeed be occupied by N-glycan. Furthermore we showed that the lack of N-glycosylation decreases the secretion of irisin, which is relevant to the instability of FNDC5 and the deficiency of cleavage of the signal peptide. We also found that the expression level of N-glycosylated FNDC5 was elevated after myoblast differentiation. These findings show that the secretion of irisin is modulated by N-glycosylation, which in turn enhances our understanding of the secretion of glycosylated irisin.
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Esmail S, Kartner N, Yao Y, Kim JW, Reithmeier RAF, Manolson MF. N-linked glycosylation of a subunit isoforms is critical for vertebrate vacuolar H + -ATPase (V-ATPase) biosynthesis. J Cell Biochem 2017; 119:861-875. [PMID: 28661051 DOI: 10.1002/jcb.26250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 06/28/2017] [Indexed: 12/12/2022]
Abstract
The a subunit of the V0 membrane-integrated sector of human V-ATPase has four isoforms, a1-a4, with diverse and crucial functions in health and disease. They are encoded by four conserved paralogous genes, and their vertebrate orthologs have positionally conserved N-glycosylation sequons within the second extracellular loop, EL2, of the a subunit membrane domain. Previously, we have shown directly that the predicted sequon for the a4 isoform is indeed N-glycosylated. Here we extend our investigation to the other isoforms by transiently transfecting HEK 293 cells to express cDNA constructs of epitope-tagged human a1-a3 subunits, with or without mutations that convert Asn to Gln at putative N-glycosylation sites. Expression and N-glycosylation were characterized by immunoblotting and mobility shifts after enzymatic deglycosylation, and intracellular localization was determined using immunofluorescence microscopy. All unglycosylated mutants, where predicted N-glycosylation sites had been eliminated by sequon mutagenesis, showed increased relative mobility on immunoblots, identical to what was seen for wild-type a subunits after enzymatic deglycosylation. Cycloheximide-chase experiments showed that unglycosylated subunits were turned over at a higher rate than N-glycosylated forms by degradation in the proteasomal pathway. Immunofluorescence colocalization analysis showed that unglycosylated a subunits were retained in the ER, and co-immunoprecipitation studies showed that they were unable to associate with the V-ATPase assembly chaperone, VMA21. Taken together with our previous a4 subunit studies, these observations show that N-glycosylation is crucial in all four human V-ATPase a subunit isoforms for protein stability and ultimately for functional incorporation into V-ATPase complexes.
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Affiliation(s)
- Sally Esmail
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Norbert Kartner
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Yeqi Yao
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Joo Wan Kim
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
| | | | - Morris F Manolson
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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