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Liu H, Tan R, Tong J, Wen S, Wu C, Rao M, Zhu J, Qi S, Kong E. Palmitoylation is required for Sept8-204 and Sept5 to form vesicle-like structure and colocalize with synaptophysin. J Cell Biochem 2024; 125:e30529. [PMID: 38308620 DOI: 10.1002/jcb.30529] [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: 01/09/2024] [Accepted: 01/24/2024] [Indexed: 02/05/2024]
Abstract
Sept8 is a vesicle associated protein and there are two typical transcriptional variants (Sept8-204 and Sept8-201) expressed in mice brain. Interestingly, the coexpression of Sept8-204/Sept5 induces the formation of small sized vesicle-like structure, while that of the Sept8-201/Sept5 produces large puncta. Sept8 is previously shown to be palmitoylated. Here it was further revealed that protein palmitoylation is required for Sept8-204/Sept5 to maintain small sized vesicle-like structure and colocalize with synaptophysin, since either the expression of nonpalmitoylated Sept8-204 mutant (Sept8-204-3CA) or inhibiting Sept8-204 palmitoylation by 2-BP with Sept5 produces large puncta, which barely colocalizes with synaptophysin (SYP). Moreover, it was shown that the dynamic palmitoylation of Sept8-204 is controlled by ZDHHC17 and PPT1, loss of ZDHHC17 decreases Sept8-204 palmitoylation and induces large puncta, while loss of PPT1 increases Sept8-204 palmitoylation and induces small sized vesicle-like structure. Together, these findings suggest that palmitoylation is essential for the maintenance of the small sized vesicle-like structure for Sept8-204/Sept5, and may hint their important roles in synaptic functions.
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Affiliation(s)
- Huicong Liu
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Rong Tan
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Jia Tong
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Shuo Wen
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Can Wu
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Muding Rao
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Jiangli Zhu
- State Key Laboratory of Biotherapy and Cancer Center, Department of Urology, Sichuan University and National Collaborative Innovation Center, Chengdu, China
| | - Shiqian Qi
- State Key Laboratory of Biotherapy and Cancer Center, Department of Urology, Sichuan University and National Collaborative Innovation Center, Chengdu, China
| | - Eryan Kong
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
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2
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Song M, Qiang Y, Zhao X, Song F. Cyclin-dependent Kinase 5 and Neurodegenerative Diseases. Mol Neurobiol 2024:10.1007/s12035-024-04047-1. [PMID: 38378992 DOI: 10.1007/s12035-024-04047-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 02/07/2024] [Indexed: 02/22/2024]
Abstract
Neurodegenerative diseases are a group of diseases characterized by the progressive loss of neurons, including Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis. These diseases have a high incidence and mortality rate globally, placing a heavy burden on patients and their families. The pathogenesis of neurodegenerative diseases is complex, and there are no effective treatments at present. Cyclin-dependent kinase 5 is a proline-directed serine/threonine protein kinase that is closely related to the development and function of the nervous system. Under physiological conditions, it is involved in regulating the process of neuronal proliferation, differentiation, migration, and synaptic plasticity. Moreover, there is increasing evidence that cyclin-dependent kinase 5 also plays an important role in the pathogenesis of neurodegenerative diseases. In this review, we address the biological characteristics of cyclin-dependent kinase 5 and its role in neurodegenerative diseases. In particular, this review highlights the underlying mechanistic linkages between cyclin-dependent kinase 5 and mitochondrial dysfunction, oxidative stress and neuroinflammation in the context of neurodegeneration. Finally, we also summarize the currently available cyclin-dependent kinase 5 inhibitors and their prospects for the treatment of neurodegenerative diseases. Taken together, a better understanding of the molecular mechanisms of cyclin-dependent kinase 5 involved in neurodegenerative diseases can lead to the development of new strategies for the prevention and treatment of these devastating diseases.
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Affiliation(s)
- Mingxue Song
- Department of Toxicology and Nutrition, School of Public Health, Cheeloo College of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong, 250012, People's Republic of China
| | - Yalong Qiang
- Department of Toxicology and Nutrition, School of Public Health, Cheeloo College of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong, 250012, People's Republic of China
| | - Xiulan Zhao
- Department of Toxicology and Nutrition, School of Public Health, Cheeloo College of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong, 250012, People's Republic of China
| | - Fuyong Song
- Department of Toxicology and Nutrition, School of Public Health, Cheeloo College of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong, 250012, People's Republic of China.
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Perry JA, Werner ME, Heck BW, Maddox PS, Maddox AS. Septins throughout phylogeny are predicted to have a transmembrane domain, which in Caenorhabditis elegans is functionally important. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567915. [PMID: 38045322 PMCID: PMC10690161 DOI: 10.1101/2023.11.20.567915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Septins, a conserved family of filament-forming proteins, contribute to eukaryotic cell division, polarity, and membrane trafficking. Septins are thought to act in these processes by scaffolding other proteins to the plasma membrane. The mechanisms by which septins associate with the plasma membrane are not well understood but can involve two polybasic domains and/or an amphipathic helix. We discovered that the genomes of organisms throughout phylogeny, but not most commonly used model organisms, encode one or more septins predicted to have transmembrane domains. The nematode Caenorhabditis elegans, which was thought to express only two septin proteins, UNC-59 and UNC-61, translates multiple isoforms of UNC-61, and one isoform, UNC-61a, is predicted to contain a transmembrane domain. UNC-61a localizes specifically to the apical membrane of the C. elegans vulva and is important for maintaining vulval morphology. UNC-61a partially compensates for the loss of the other two UNC-61 isoforms, UNC-61b and UNC-61c. The UNC-61a transmembrane domain is sufficient to localize a fluorophore to membranes in mammalian cells, and its deletion from UNC-61a recapitulates the phenotypes of unc-61a null animals. The localization and loss-of-function phenotypes of UNC-61a and its transmembrane domain suggest roles in cell polarity and secretion and help explain the cellular and tissue biological underpinnings of C. elegans septin null alleles' enigmatically hypomorphic phenotypes. Together, our findings reveal a novel mechanism of septin-membrane association with profound implications for the dynamics and regulation of this association.
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Affiliation(s)
- Jenna A Perry
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Michael E Werner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Bryan W Heck
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
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4
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Yu L, Xu L, Chu H, Peng J, Sacharidou A, Hsieh HH, Weinstock A, Khan S, Ma L, Durán JGB, McDonald J, Nelson ER, Park S, McDonnell DP, Moore KJ, Huang LJS, Fisher EA, Mineo C, Huang L, Shaul PW. Macrophage-to-endothelial cell crosstalk by the cholesterol metabolite 27HC promotes atherosclerosis in male mice. Nat Commun 2023; 14:4101. [PMID: 37491347 PMCID: PMC10368733 DOI: 10.1038/s41467-023-39586-z] [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: 04/06/2023] [Accepted: 06/20/2023] [Indexed: 07/27/2023] Open
Abstract
Hypercholesterolemia and vascular inflammation are key interconnected contributors to the pathogenesis of atherosclerosis. How hypercholesterolemia initiates vascular inflammation is poorly understood. Here we show in male mice that hypercholesterolemia-driven endothelial activation, monocyte recruitment and atherosclerotic lesion formation are promoted by a crosstalk between macrophages and endothelial cells mediated by the cholesterol metabolite 27-hydroxycholesterol (27HC). The pro-atherogenic actions of macrophage-derived 27HC require endothelial estrogen receptor alpha (ERα) and disassociation of the cytoplasmic scaffolding protein septin 11 from ERα, leading to extranuclear ERα- and septin 11-dependent activation of NF-κB. Furthermore, pharmacologic inhibition of cyp27a1, which generates 27HC, affords atheroprotection by reducing endothelial activation and monocyte recruitment. These findings demonstrate cell-to-cell communication by 27HC, and identify a major causal linkage between the hypercholesterolemia and vascular inflammation that partner to promote atherosclerosis. Interventions interrupting this linkage may provide the means to blunt vascular inflammation without impairing host defense to combat the risk of atherosclerotic cardiovascular disease that remains despite lipid-lowering therapies.
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Affiliation(s)
- Liming Yu
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Lin Xu
- Quantitative Biomedical Research Center and Peter O'Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Haiyan Chu
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jun Peng
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Anastasia Sacharidou
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Hsi-Hsien Hsieh
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ada Weinstock
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
- Department of Medicine, University of Chicago School of Medicine, Chicago, IL, 60637, USA
| | - Sohaib Khan
- University of Cincinnati Cancer Center, Cincinnati, OH, 45267, USA
| | - Liqian Ma
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | | | - Jeffrey McDonald
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Erik R Nelson
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Sunghee Park
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Donald P McDonnell
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Kathryn J Moore
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Lily Jun-Shen Huang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Edward A Fisher
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Chieko Mineo
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Linzhang Huang
- State Key Laboratory of Genetic Engineering, Fudan University, Shanghai, 200433, China.
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Fudan University, Shanghai, 200433, China.
- Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, 200433, China.
| | - Philip W Shaul
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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Sharma K, Menon MB. Decoding post-translational modifications of mammalian septins. Cytoskeleton (Hoboken) 2023; 80:169-181. [PMID: 36797225 DOI: 10.1002/cm.21747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/21/2023] [Accepted: 02/10/2023] [Indexed: 02/18/2023]
Abstract
Septins are cytoskeletal GTPases that form nonpolar filaments and higher-ordered structures and they take part in a wide range of cellular processes. Septins are conserved from yeast to mammals but absent from higher plants. The number of septin genes vary between organisms and they usually form complex heteropolymeric networks. Most septins are known to be capable of GTP hydrolysis which may regulate septin dynamics. Knowledge on regulation of septin function by post-translational modifications is still in its infancy. In this review article, we highlight the post-translational modifications reported for the 13 human septins and discuss their implications on septin functions. In addition to the functionally investigated modifications, we also try to make sense of the complex septin post-translational modification code revealed from large-scale phospho-proteomic datasets. Future studies may determine how these isoform-specific and homology group specific modifications affect septin structure and function.
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Affiliation(s)
- Khushboo Sharma
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Manoj B Menon
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
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6
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Werner B, Yadav S. Phosphoregulation of the septin cytoskeleton in neuronal development and disease. Cytoskeleton (Hoboken) 2023; 80:275-289. [PMID: 36127729 PMCID: PMC10025170 DOI: 10.1002/cm.21728] [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: 06/17/2022] [Revised: 08/13/2022] [Accepted: 09/12/2022] [Indexed: 11/06/2022]
Abstract
Septins are highly conserved GTP-binding proteins that oligomerize and form higher order structures. The septin cytoskeleton plays an important role in cellular organization, intracellular transport, and cytokinesis. Kinase-mediated phosphorylation of septins regulates various aspects of their function, localization, and dynamics. Septins are enriched in the mammalian nervous system where they contribute to neurodevelopment and neuronal function. Emerging research has implicated aberrant changes in septin cytoskeleton in several human diseases. The mechanisms through which aberrant phosphorylation by kinases contributes to septin dysfunction in neurological disorders are poorly understood and represent an important question for future research with therapeutic implications. This review summarizes the current state of knowledge of the diversity of kinases that interact with and phosphorylate mammalian septins, delineates how phosphoregulation impacts septin dynamics, and describes how aberrant septin phosphorylation contributes to neurological disorders.
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Affiliation(s)
- Bailey Werner
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Smita Yadav
- Department of Pharmacology, University of Washington, Seattle, WA, United States
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7
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Radler MR, Spiliotis ET. Right place, right time - Spatial guidance of neuronal morphogenesis by septin GTPases. Curr Opin Neurobiol 2022; 75:102557. [PMID: 35609489 PMCID: PMC9968515 DOI: 10.1016/j.conb.2022.102557] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 04/07/2022] [Accepted: 04/20/2022] [Indexed: 12/21/2022]
Abstract
Neuronal morphogenesis is guided by outside-in signals and inside-out mechanisms, which require spatiotemporal precision. How the intracellular mechanisms of neuronal morphogenesis are spatiotemporally controlled is not well understood. Septins comprise a unique GTPase module, which consists of complexes with differential localizations and functions. Septins demarcate distinct membrane domains in neural precursor cells, orienting the axis of cell division and the sites of neurite formation. By controlling the localization of membrane and cytoskeletal proteins, septins promote axon-dendrite formation and polarity. Furthermore, septins modulate vesicle exocytosis at pre-synaptic terminals, and stabilize dendritic spines and post-synaptic densities in a phospho-regulatable manner. We posit that neuronal septins are topologically and functionally specialized for the spatiotemporal regulation of neuronal morphogenesis and plasticity.
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Affiliation(s)
- Megan R. Radler
- Department of Biology, Drexel University, Papadakis Integrated Sciences Building 423, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Elias T. Spiliotis
- Department of Biology, Drexel University, Papadakis Integrated Sciences Building 423, 3245 Chestnut St, Philadelphia, PA 19104, USA
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8
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S327 phosphorylation of the presynaptic protein SEPTIN5 increases in the early stages of neurofibrillary pathology and alters the functionality of SEPTIN5. Neurobiol Dis 2022; 163:105603. [DOI: 10.1016/j.nbd.2021.105603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/02/2021] [Accepted: 12/22/2021] [Indexed: 12/25/2022] Open
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9
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Satake SI, Konishi S. Topographical distance between presynaptic Ca 2+ channels and exocytotic Ca 2+ sensors contributes to differential facilitatory actions of roscovitine on neurotransmitter release at cerebellar glutamatergic and GABAergic synapses. Eur J Neurosci 2021; 54:7048-7062. [PMID: 34622493 DOI: 10.1111/ejn.15487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 09/27/2021] [Accepted: 09/29/2021] [Indexed: 11/29/2022]
Abstract
Calcium influx into presynaptic terminals through voltage-gated Ca2+ channels triggers univesicular or multivesicular release of neurotransmitters depending on the characteristics of the release machinery. However, the mechanisms underlying multivesicular release (MVR) and its regulation remain unclear. Previous studies showed that in rat cerebellum, the cyclin-dependent kinase inhibitor roscovitine profoundly increases excitatory postsynaptic current (EPSC) amplitudes at granule cell (GC)-Purkinje cell (PC) synapses by enhancing the MVR of glutamate. This compound can also moderately augment the amplitude and prolong the decay time of inhibitory postsynaptic currents (IPSCs) at molecular layer interneuron (MLI)-PC synapses via MVR enhancement and GABA spillover, thus allowing for persistent activation of perisynaptic GABA receptors. The enhanced MVR may depend on the driving force for Cav 2.1 channel-mediated Ca2+ influx. To determine whether the distinct spatiotemporal dynamics of presynaptic Ca2+ influence MVR, we compared the effects of slow and fast Ca2+ chelators, that is, EGTA and BAPTA, respectively, on roscovitine-induced actions at GC-PC and MLI-PC synapses. Membrane-permeable EGTA-AM decreased GC-PC EPSC and MLI-PC IPSC amplitudes to a similar extent but suppressed the roscovitine-induced enhancement of EPSCs. In contrast, BAPTA-AM attenuated the effects of roscovitine on IPSCs. These results suggest that roscovitine augmented glutamate release by activating the release machinery located distally from the Cav 2.1 channel clusters, while it enhanced GABA release in a manner less dependent on those at distal sites. Therefore, the spatial relationships among Ca2+ channels, buffers, and sensors are critical determinants of the differential facilitatory actions of roscovitine on glutamatergic and GABAergic synapses in the cerebellar cortex.
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Affiliation(s)
- Shin' Ichiro Satake
- Brain Research Support Center, National Institute for Physiological Sciences (NIPS), Okazaki, Japan.,School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Shiro Konishi
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
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10
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Belalcazar HM, Hendricks EL, Zamurrad S, Liebl FLW, Secombe J. The histone demethylase KDM5 is required for synaptic structure and function at the Drosophila neuromuscular junction. Cell Rep 2021; 34:108753. [PMID: 33596422 PMCID: PMC7945993 DOI: 10.1016/j.celrep.2021.108753] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/14/2020] [Accepted: 01/25/2021] [Indexed: 02/08/2023] Open
Abstract
Mutations in the genes encoding the lysine demethylase 5 (KDM5) family of histone demethylases are observed in individuals with intellectual disability (ID). Despite clear evidence linking KDM5 function to neurodevelopmental pathways, how this family of proteins impacts transcriptional programs to mediate synaptic structure and activity remains unclear. Using the Drosophila larval neuromuscular junction (NMJ), we show that KDM5 is required presynaptically for neuroanatomical development and synaptic function. The Jumonji C (JmjC) domain-encoded histone demethylase activity of KDM5, which is expected to be diminished by many ID-associated alleles, is required for appropriate synaptic morphology and neurotransmission. The activity of the C5HC2 zinc finger is also required, as an ID-associated mutation in this motif reduces NMJ bouton number, increases bouton size, and alters microtubule dynamics. KDM5 therefore uses demethylase-dependent and independent mechanisms to regulate NMJ structure and activity, highlighting the complex nature by which this chromatin modifier carries out its neuronal gene-regulatory programs.
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Affiliation(s)
- Helen M Belalcazar
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Emily L Hendricks
- Department of Biological Sciences, Southern Illinois University Edwardsville, 44 Circle Drive, Edwardsville, IL 62026, USA
| | - Sumaira Zamurrad
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Faith L W Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, 44 Circle Drive, Edwardsville, IL 62026, USA
| | - Julie Secombe
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461, USA.
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11
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Ageta-Ishihara N, Kinoshita M. Developmental and postdevelopmental roles of septins in the brain. Neurosci Res 2020; 170:6-12. [PMID: 33159992 DOI: 10.1016/j.neures.2020.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/21/2020] [Accepted: 08/23/2020] [Indexed: 11/25/2022]
Abstract
Morphogenetic processes during brain development and postdevelopmental remodeling of neural architecture depend on the exquisite interplay between the microtubule- and actin-based cytoskeletal systems. Accumulation of evidence indicates cooperative roles of another cytoskeletal system composed of the septin family. Here we overview experimental findings on mammalian septins and their hypothetical roles in the proliferation of neural progenitor cells, neurite development, synapse formation and regulations. The diverse, mostly unexpected phenotypes obtained from gain- and loss-of-function mutants point to unknown molecular network to be elucidated, which may underlie pathogenetic processes of infectious diseases and neuropsychiatric disorders in humans.
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Affiliation(s)
- Natsumi Ageta-Ishihara
- Division of Biological Science, Nagoya University Graduate School of Science, Furo, Chikusa, Nagoya 464-8602, Japan.
| | - Makoto Kinoshita
- Division of Biological Science, Nagoya University Graduate School of Science, Furo, Chikusa, Nagoya 464-8602, Japan.
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12
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Nakos K, Radler MR, Spiliotis ET. Septin 2/6/7 complexes tune microtubule plus-end growth and EB1 binding in a concentration- and filament-dependent manner. Mol Biol Cell 2019; 30:2913-2928. [PMID: 31577529 PMCID: PMC6822581 DOI: 10.1091/mbc.e19-07-0362] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Septins (SEPTs) are filamentous guanosine-5′-triphosphate (GTP)-binding proteins, which affect microtubule (MT)-dependent functions including membrane trafficking and cell division, but their precise role in MT dynamics is poorly understood. Here, in vitro reconstitution of MT dynamics with SEPT2/6/7, the minimal subunits of septin heteromers, shows that SEPT2/6/7 has a biphasic concentration-dependent effect on MT growth. Lower concentrations of SEPT2/6/7 enhance MT plus-end growth and elongation, while higher and intermediate concentrations inhibit and pause plus-end growth, respectively. We show that SEPT2/6/7 has a modest preference for GTP- over guanosine diphosphate (GDP)-bound MT lattice and competes with end-binding protein 1 (EB1) for binding to guanosine 5′-O-[γ-thio]triphosphate (GTPγS)-stabilized MTs, which mimic the EB1-preferred GDP-Pi state of polymerized tubulin. Strikingly, SEPT2/6/7 triggers EB1 dissociation from plus-end tips in cis by binding to the MT lattice and in trans when MT plus ends collide with SEPT2/6/7 filaments. At these intersections, SEPT2/6/7 filaments were more potent barriers than actin filaments in pausing MT growth and dissociating EB1 in vitro and in live cells. These data demonstrate that SEPT2/6/7 complexes and filaments can directly impact MT plus-end growth and the tracking of plus end–binding proteins and thereby may facilitate the capture of MT plus ends at intracellular sites of septin enrichment.
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Affiliation(s)
| | - Megan R Radler
- Department of Biology, Drexel University, Philadelphia, PA 19104
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13
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Motahari Z, Moody SA, Maynard TM, LaMantia AS. In the line-up: deleted genes associated with DiGeorge/22q11.2 deletion syndrome: are they all suspects? J Neurodev Disord 2019; 11:7. [PMID: 31174463 PMCID: PMC6554986 DOI: 10.1186/s11689-019-9267-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 04/21/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND 22q11.2 deletion syndrome (22q11DS), a copy number variation (CNV) disorder, occurs in approximately 1:4000 live births due to a heterozygous microdeletion at position 11.2 (proximal) on the q arm of human chromosome 22 (hChr22) (McDonald-McGinn and Sullivan, Medicine 90:1-18, 2011). This disorder was known as DiGeorge syndrome, Velo-cardio-facial syndrome (VCFS) or conotruncal anomaly face syndrome (CTAF) based upon diagnostic cardiovascular, pharyngeal, and craniofacial anomalies (McDonald-McGinn and Sullivan, Medicine 90:1-18, 2011; Burn et al., J Med Genet 30:822-4, 1993) before this phenotypic spectrum was associated with 22q11.2 CNVs. Subsequently, 22q11.2 deletion emerged as a major genomic lesion associated with vulnerability for several clinically defined behavioral deficits common to a number of neurodevelopmental disorders (Fernandez et al., Principles of Developmental Genetics, 2015; Robin and Shprintzen, J Pediatr 147:90-6, 2005; Schneider et al., Am J Psychiatry 171:627-39, 2014). RESULTS The mechanistic relationships between heterozygously deleted 22q11.2 genes and 22q11DS phenotypes are still unknown. We assembled a comprehensive "line-up" of the 36 protein coding loci in the 1.5 Mb minimal critical deleted region on hChr22q11.2, plus 20 protein coding loci in the distal 1.5 Mb that defines the 3 Mb typical 22q11DS deletion. We categorized candidates based upon apparent primary cell biological functions. We analyzed 41 of these genes that encode known proteins to determine whether haploinsufficiency of any single 22q11.2 gene-a one gene to one phenotype correspondence due to heterozygous deletion restricted to that locus-versus complex multigenic interactions can account for single or multiple 22q11DS phenotypes. CONCLUSIONS Our 22q11.2 functional genomic assessment does not support current theories of single gene haploinsufficiency for one or all 22q11DS phenotypes. Shared molecular functions, convergence on fundamental cell biological processes, and related consequences of individual 22q11.2 genes point to a matrix of multigenic interactions due to diminished 22q11.2 gene dosage. These interactions target fundamental cellular mechanisms essential for development, maturation, or homeostasis at subsets of 22q11DS phenotypic sites.
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Affiliation(s)
- Zahra Motahari
- The Institute for Neuroscience, and Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, 20037 USA
| | - Sally Ann Moody
- The Institute for Neuroscience, and Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, 20037 USA
| | - Thomas Michael Maynard
- The Institute for Neuroscience, and Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, 20037 USA
| | - Anthony-Samuel LaMantia
- The Institute for Neuroscience, and Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, 20037 USA
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14
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Reorganization of Septins Modulates Synaptic Transmission at Neuromuscular Junctions. Neuroscience 2019; 404:91-101. [PMID: 30738855 DOI: 10.1016/j.neuroscience.2019.01.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 01/27/2019] [Accepted: 01/29/2019] [Indexed: 12/24/2022]
Abstract
Septins (Sept) are highly conserved Guanosine-5'-triphosphate (GTP)-binding cytoskeletal proteins involved in neuronal signaling in the central nervous system but their involvement in signal transmission in peripheral synapses remains unclear. Sept5 and Sept9 proteins were detected in mouse peripheral neuromuscular junctions by immunofluorescence with a greater degree of co-localization with presynaptic than postsynaptic membranes. Preincubation of neuromuscular junction preparations with the inhibitor of Sept dynamics, forchlorfenuron (FCF), decreased co-localization of Sept with presynaptic membranes. FCF introduced ex vivo or in vivo had no effect on the amplitude of the spontaneous endplate currents (EPCs), indicating the absence of postsynaptic effects of FCF. However, FCF decreased acetylcholine (ACh) quantal release in response to nerve stimulation, reduced the amplitude of evoked quantal currents and decreased the number of quanta with long synaptic delays, demonstrating the presynaptic action of FCF. Nevertheless, FCF had no effect on the amplitude of calcium transient in nerve terminals, as detected by calcium-sensitive dye, and slightly decreased the ratio of the second response amplitude to the first one in paired-pulse experiments. These results suggest that FCF-induced decrease in ACh quantal secretion is not due to a decrease in Ca2+ influx but is likely related to the impairment of later stages occurring after Ca2+ entry, such as trafficking, docking or membrane fusion of synaptic vesicles. Therefore, Sept9 and Sept5 are abundantly expressed in presynaptic membranes, and disruption of Sept dynamics suppresses the evoked synchronous and delayed asynchronous quantal release of ACh, strongly suggesting an important role of Sept in the regulation of neurotransmission in peripheral synapses.
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15
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Lin CH, Shen YR, Wang HY, Chiang CW, Wang CY, Kuo PL. Regulation of septin phosphorylation: SEPT12 phosphorylation in sperm septin assembly. Cytoskeleton (Hoboken) 2018; 76:137-142. [PMID: 30160375 DOI: 10.1002/cm.21491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 08/08/2018] [Accepted: 08/12/2018] [Indexed: 12/11/2022]
Abstract
The sperm annulus, a septin-based ring structure, is important for reproductive physiology. It is composed of SEPT12-based septin core complex followed by assembling as octameric filament. In clinical examinations, mutations of Septin12 result in male infertility, immotile sperm, as well as sperm with defective annuli. The dynamic assembly of septin filaments is regulated by several post-translational modifications, including sumoylation, acetylation, and phosphorylation. Here, we briefly review the biological significance and the regulation of SEPT12 phosphorylation in the mammalian sperm physiology. During mammalian spermiogenesis, the phosphorylation of SEPT12 on Ser198 residue is important in regulating mammalian annulus architectures. SEPT12 phosphomimetic knock-in mice displayed poor male fertility due to weak sperm motility and loss of the sperm annulus. SEPT12 is phosphorylated via Protein kinase A (PKA), and its phosphorylation interfered with SEPT12 polymerization into complexes and filaments. Taken together, the phosphorylation status of SEPT12 is crucial for its function in regulating the mammalian sperm physiology.
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Affiliation(s)
- Chun-Hsiang Lin
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Ru Shen
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Han-Yu Wang
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chi-Wu Chiang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chia-Yih Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Pao-Lin Kuo
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Obstetrics and Gynecology, National Cheng-Kung University Hospital, Tainan, Taiwan
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16
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Akhmetova KA, Chesnokov IN, Fedorova SA. [Functional Characterization of Septin Complexes]. Mol Biol (Mosk) 2018; 52:155-171. [PMID: 29695686 DOI: 10.7868/s0026898418020015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/27/2016] [Indexed: 12/28/2022]
Abstract
Septins belong to a family of conserved GTP-binding proteins found in majority of eukaryotic species except for higher plants. Septins form nonpolar complexes that further polymerize into filaments and associate with cell membranes, thus comprising newly acknowledged cytoskeletal system. Septins participate in a variety of cell processes and contribute to various pathophysiological states, including tumorigenesis and neurodegeneration. Here, we review the structural and functional properties of septins and the regulation of their dynamics with special emphasis on the role of septin filaments as a cytoskeletal system and its interaction with actin and microtubule cytoskeletons. We also discuss how septins compartmentalize the cell by forming local protein-anchoring scaffolds and by providing barriers for the lateral diffusion of the membrane proteins.
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Affiliation(s)
- K A Akhmetova
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.,University of Alabama at Birmingham, Birmingham, 35294 USA.,Novosibirsk National Research State University, Novosibirsk, 630090 Russia
| | - I N Chesnokov
- University of Alabama at Birmingham, Birmingham, 35294 USA
| | - S A Fedorova
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.,Novosibirsk National Research State University, Novosibirsk, 630090 Russia.,
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17
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Wasik AA, Dash SN, Lehtonen S. Septins in kidney: A territory little explored. Cytoskeleton (Hoboken) 2018; 76:154-162. [PMID: 30004646 PMCID: PMC6585700 DOI: 10.1002/cm.21477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/15/2018] [Accepted: 07/03/2018] [Indexed: 12/15/2022]
Abstract
Septins are a conserved family of GTP‐binding proteins that assemble into cytoskeletal filaments to function in a highly sophisticated and physiologically regulated manner. Originally septins were discovered in the budding yeast as membrane‐associated filaments that affect cell polarity and cytokinesis. In the last decades, much progress has been made in understanding the biochemical properties and cell biological functions of septins. In line with this, mammalian septins have been shown to be involved in various cellular processes, including regulation of cell polarity, cytoskeletal organization, vesicle trafficking, ciliogenesis, and cell–pathogen interactions. A growing number of studies have shown that septins play important roles in tissue and organ development and physiology; yet, little is known about their role in the kidney. In the following review, we discuss the structure and functions of septins in general and summarize the evidence for their presence and roles in the kidney.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Surjya N Dash
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, Helsinki, Finland
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18
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Honorat JA, Lopez-Chiriboga AS, Kryzer TJ, Fryer JP, Devine M, Flores A, Lennon VA, Pittock SJ, McKeon A. Autoimmune septin-5 cerebellar ataxia. NEUROLOGY-NEUROIMMUNOLOGY & NEUROINFLAMMATION 2018; 5:e474. [PMID: 29998156 PMCID: PMC6039209 DOI: 10.1212/nxi.0000000000000474] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/21/2018] [Indexed: 01/08/2023]
Abstract
Objective To report a form of autoimmune cerebellar ataxia in which antibodies target septin-5, a guanosine triphosphate (GTP)-binding neural protein involved in neurotransmitter exocytosis. Methods Archived sera and CSF specimens with unclassified synaptic antibodies were re-evaluated by tissue-based indirect immunofluorescence assay. Autoantigens were identified by Western blot and mass spectrometry. Recombinant protein assays (Western blot, cell based, and protein screening array) confirmed antigen specificity. Results Serum and CSF from 6 patients produced identical synaptic immunoglobulin G (IgG) staining patterns of synaptic regions (neuropil) of the mouse cerebrum and cerebellum. The molecular layer of the cerebellum and the thalamus demonstrated stronger immunoreactivity than the midbrain, hippocampus, cortex, and basal ganglia. The antigen revealed by mass spectrometry analysis of immunoprecipitated cerebellar proteins and confirmed by recombinant protein assays was septin-5. All 4 patients with records available had subacute onset of cerebellar ataxia with prominent eye movement symptoms (oscillopsia or vertigo). None had cancer detected. Improvements occurred after immunotherapies (2) or spontaneously (1). One patient died. Conclusion Septin-5 IgG represents a biomarker for a potentially fatal but treatable autoimmune ataxia.
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Affiliation(s)
- Josephe A Honorat
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - A Sebastian Lopez-Chiriboga
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Thomas J Kryzer
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - James P Fryer
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Michelle Devine
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Angela Flores
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Vanda A Lennon
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Sean J Pittock
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Andrew McKeon
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
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19
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Hiroi N. Critical reappraisal of mechanistic links of copy number variants to dimensional constructs of neuropsychiatric disorders in mouse models. Psychiatry Clin Neurosci 2018; 72:301-321. [PMID: 29369447 PMCID: PMC5935536 DOI: 10.1111/pcn.12641] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 12/27/2017] [Accepted: 01/19/2018] [Indexed: 12/17/2022]
Abstract
Copy number variants are deletions and duplications of a few thousand to million base pairs and are associated with extraordinarily high levels of autism spectrum disorder, schizophrenia, intellectual disability, or attention-deficit hyperactivity disorder. The unprecedented levels of robust and reproducible penetrance of copy number variants make them one of the most promising and reliable entry points to delve into the mechanistic bases of many mental disorders. However, the precise mechanistic bases of these associations still remain elusive in humans due to the many genes encoded in each copy number variant and the diverse associated phenotypic features. Genetically engineered mice have provided a technical means to ascertain precise genetic mechanisms of association between copy number variants and dimensional aspects of mental illnesses. Molecular, cellular, and neuronal phenotypes can be detected as potential mechanistic substrates for various behavioral constructs of mental illnesses. However, mouse models come with many technical pitfalls. Genetic background is not well controlled in many mouse models, leading to rather obvious interpretative issues. Dose alterations of many copy number variants and single genes within copy number variants result in some molecular, cellular, and neuronal phenotypes without a behavioral phenotype or with a behavioral phenotype opposite to what is seen in humans. In this review, I discuss technical and interpretative pitfalls of mouse models of copy number variants and highlight well-controlled studies to suggest potential neuronal mechanisms of dimensional aspects of mental illnesses. Mouse models of copy number variants represent toeholds to achieve a better understanding of the mechanistic bases of dimensions of neuropsychiatric disorders and thus for development of mechanism-based therapeutic options in humans.
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Affiliation(s)
- Noboru Hiroi
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, New York, USA.,Department of Neuroscience, Albert Einstein College of Medicine, New York, USA.,Department of Genetics, Albert Einstein College of Medicine, New York, USA
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20
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21
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Phosphorylation of Pnut in the Early Stages of Drosophila Embryo Development Affects Association of the Septin Complex with the Membrane and Is Important for Viability. G3-GENES GENOMES GENETICS 2018; 8:27-38. [PMID: 29079679 PMCID: PMC5765355 DOI: 10.1534/g3.117.300186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Septin proteins are polymerizing GTPases that are found in most eukaryotic species. Septins are important for cytokinesis and participate in many processes involving spatial modifications of the cell cortex. In Drosophila, septin proteins Pnut, Sep1, and Sep2 form a hexameric septin complex. Here, we found that septin protein Pnut is phosphorylated during the first 2 hr of Drosophila embryo development. To study the effect of Pnut phosphorylation in a live organism, we created a new Drosophila pnut null mutant that allows for the analysis of Pnut mutations during embryogenesis. To understand the functional significance of Pnut phosphorylation, Drosophila strains carrying nonphosphorylatable and phospho-mimetic mutant pnut transgenes were established. The expression of the nonphosphorylatable Pnut protein resulted in semilethality and abnormal protein localization, whereas the expression of the phospho-mimetic mutant form of Pnut disrupted the assembly of a functional septin complex and septin filament formation in vitro. Overall, our findings indicate that the controlled phosphorylation of Pnut plays an important role in regulating septin complex functions during organism development.
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22
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Palander O, El-Zeiry M, Trimble WS. Uncovering the Roles of Septins in Cilia. Front Cell Dev Biol 2017; 5:36. [PMID: 28428954 PMCID: PMC5382219 DOI: 10.3389/fcell.2017.00036] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/23/2017] [Indexed: 01/22/2023] Open
Abstract
Septins are a family of GTP-binding proteins that associate with cellular membranes and the cytoskeleton. Their ability to polymerize into filamentous structures permits them to serve as diffusion barriers for membrane proteins and as multi-molecular scaffolds that recruit components of signaling pathways. At the cellular level, septins contribute to the regulation of numerous processes, including cytokinesis, cell polarity, cell migration, and many others. In this review, we discuss emerging evidence for roles of mammalian septins in the biogenesis and function of flagella and cilia, and how this may impact human diseases such as ciliopathies.
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Affiliation(s)
- Oliva Palander
- Cell Biology Program, Hospital for Sick ChildrenToronto, ON, Canada.,Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - Maha El-Zeiry
- Cell Biology Program, Hospital for Sick ChildrenToronto, ON, Canada.,Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - William S Trimble
- Cell Biology Program, Hospital for Sick ChildrenToronto, ON, Canada.,Department of Biochemistry, University of TorontoToronto, ON, Canada.,Department of Physiology, University of TorontoToronto, ON, Canada
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23
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Vagin O, Beenhouwer DO. Septins: Regulators of Protein Stability. Front Cell Dev Biol 2016; 4:143. [PMID: 28066764 PMCID: PMC5168428 DOI: 10.3389/fcell.2016.00143] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 12/02/2016] [Indexed: 12/31/2022] Open
Abstract
Septins are small GTPases that play a role in several important cellular processes. In this review, we focus on the roles of septins in protein stabilization. Septins may regulate protein stability by: (1) interacting with proteins involved in degradation pathways, (2) regulating the interaction between transmembrane proteins and cytoskeletal proteins, (3) affecting the mobility of transmembrane proteins in lipid bilayers, and (4) modulating the interaction of proteins with their adaptor or signaling proteins. In this context, we discuss the role of septins in protecting four different proteins from degradation. First we consider botulinum neurotoxin serotype A (BoNT/A) and the contribution of septins to its extraordinarily long intracellular persistence. Next, we discuss the role of septins in stabilizing the receptor tyrosine kinases EGFR and ErbB2. Finally, we consider the contribution of septins in protecting hypoxia-inducible factor 1α (HIF-1α) from degradation.
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Affiliation(s)
- Olga Vagin
- Department of Physiology, Geffen School of Medicine at UCLALos Angeles, CA, USA; VA Greater Los Angeles Healthcare SystemLos Angeles, CA, USA
| | - David O Beenhouwer
- Department of Medicine, Geffen School of Medicine at UCLALos Angeles, CA, USA; Division of Infectious Diseases, VA Greater Los Angeles Health Care SystemLos Angeles, CA, USA
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24
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Fassio A, Fadda M, Benfenati F. Molecular Machines Determining the Fate of Endocytosed Synaptic Vesicles in Nerve Terminals. Front Synaptic Neurosci 2016; 8:10. [PMID: 27242505 PMCID: PMC4863888 DOI: 10.3389/fnsyn.2016.00010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/18/2016] [Indexed: 11/28/2022] Open
Abstract
The cycle of a synaptic vesicle (SV) within the nerve terminal is a step-by-step journey with the final goal of ensuring the proper synaptic strength under changing environmental conditions. The SV cycle is a precisely regulated membrane traffic event in cells and, because of this, a plethora of membrane-bound and cytosolic proteins are devoted to assist SVs in each step of the journey. The cycling fate of endocytosed SVs determines both the availability for subsequent rounds of release and the lifetime of SVs in the terminal and is therefore crucial for synaptic function and plasticity. Molecular players that determine the destiny of SVs in nerve terminals after a round of exo-endocytosis are largely unknown. Here we review the functional role in SV fate of phosphorylation/dephosphorylation of SV proteins and of small GTPases acting on membrane trafficking at the synapse, as they are emerging as key molecules in determining the recycling route of SVs within the nerve terminal. In particular, we focus on: (i) the cyclin-dependent kinase-5 (cdk5) and calcineurin (CN) control of the recycling pool of SVs; (ii) the role of small GTPases of the Rab and ADP-ribosylation factor (Arf) families in defining the route followed by SV in their nerve terminal cycle. These regulatory proteins together with their synaptic regulators and effectors, are molecular nanomachines mediating homeostatic responses in synaptic plasticity and potential targets of drugs modulating the efficiency of synaptic transmission.
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Affiliation(s)
- Anna Fassio
- Department of Experimental Medicine, University of GenoaGenoa, Italy; Center of Synaptic Neuroscience and Technology, Istituto Italiano di TecnologiaGenova, Italy
| | - Manuela Fadda
- Department of Experimental Medicine, University of Genoa Genoa, Italy
| | - Fabio Benfenati
- Department of Experimental Medicine, University of GenoaGenoa, Italy; Center of Synaptic Neuroscience and Technology, Istituto Italiano di TecnologiaGenova, Italy
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25
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Kurkinen KMA, Marttinen M, Turner L, Natunen T, Mäkinen P, Haapalinna F, Sarajärvi T, Gabbouj S, Kurki M, Paananen J, Koivisto AM, Rauramaa T, Leinonen V, Tanila H, Soininen H, Lucas FR, Haapasalo A, Hiltunen M. SEPT8 modulates β-amyloidogenic processing of APP by affecting the sorting and accumulation of BACE1. J Cell Sci 2016; 129:2224-38. [PMID: 27084579 DOI: 10.1242/jcs.185215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/11/2016] [Indexed: 12/21/2022] Open
Abstract
Dysfunction and loss of synapses are early pathogenic events in Alzheimer's disease. A central step in the generation of toxic amyloid-β (Aβ) peptides is the cleavage of amyloid precursor protein (APP) by β-site APP-cleaving enzyme (BACE1). Here, we have elucidated whether downregulation of septin (SEPT) protein family members, which are implicated in synaptic plasticity and vesicular trafficking, affects APP processing and Aβ generation. SEPT8 was found to reduce soluble APPβ and Aβ levels in neuronal cells through a post-translational mechanism leading to decreased levels of BACE1 protein. In the human temporal cortex, we identified alterations in the expression of specific SEPT8 transcript variants in a manner that correlated with Alzheimer's-disease-related neurofibrillary pathology. These changes were associated with altered β-secretase activity. We also discovered that the overexpression of a specific Alzheimer's-disease-associated SEPT8 transcript variant increased the levels of BACE1 and Aβ peptides in neuronal cells. These changes were related to an increased half-life of BACE1 and the localization of BACE1 in recycling endosomes. These data suggest that SEPT8 modulates β-amyloidogenic processing of APP through a mechanism affecting the intracellular sorting and accumulation of BACE1.
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Affiliation(s)
- Kaisa M A Kurkinen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Mikael Marttinen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Laura Turner
- Eisai Ltd., Bernard Katz Building, University College London, London WC1E 6BT, UK
| | - Teemu Natunen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Petra Mäkinen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Fanni Haapalinna
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Timo Sarajärvi
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Sami Gabbouj
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Mitja Kurki
- Institute of Clinical Medicine - Neurosurgery, School of Medicine, University of Eastern Finland and Neurosurgery of NeuroCenter, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Jussi Paananen
- Institute of Clinical Medicine - Neurosurgery, School of Medicine, University of Eastern Finland and Neurosurgery of NeuroCenter, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Anne M Koivisto
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Tuomas Rauramaa
- Institute of Clinical Medicine - Pathology, School of Medicine, University of Eastern Finland and Department of Pathology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Ville Leinonen
- Institute of Clinical Medicine - Neurosurgery, School of Medicine, University of Eastern Finland and Neurosurgery of NeuroCenter, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Heikki Tanila
- Department of Neurobiology, A.I. Virtanen, Institute for Molecular Sciences, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Hilkka Soininen
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Fiona R Lucas
- Eisai Ltd., Bernard Katz Building, University College London, London WC1E 6BT, UK
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland Department of Neurobiology, A.I. Virtanen, Institute for Molecular Sciences, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Mikko Hiltunen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
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Interaction of Ca(2+)-dependent activator protein for secretion 1 (CAPS1) with septin family proteins in mouse brain. Neurosci Lett 2016; 617:232-5. [PMID: 26917099 DOI: 10.1016/j.neulet.2016.02.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/18/2016] [Accepted: 02/19/2016] [Indexed: 01/22/2023]
Abstract
The Ca(2+)-dependent activator protein for secretion 1 (CAPS1) protein plays a regulatory role in the dense-core vesicle exocytosis pathway. To clarify the functions of this protein in the brain, we searched for novel interaction partners of CAPS1 by mass spectrometry. We identified a specific interaction of CAPS1 with septin family proteins. We also demonstrated that the C-terminal region of the CAPS1 protein binds to part of the deduced GTP-binding domain of septin proteins. It is possible that a tertiary complex of septin, CAPS, and syntaxin contributes to dense-core vesicle trafficking and exocytosis in neurons.
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Zhang X, Belkina N, Jacob HKC, Maity T, Biswas R, Venugopalan A, Shaw PG, Kim MS, Chaerkady R, Pandey A, Guha U. Identifying novel targets of oncogenic EGF receptor signaling in lung cancer through global phosphoproteomics. Proteomics 2015; 15:340-55. [PMID: 25404012 DOI: 10.1002/pmic.201400315] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/24/2014] [Accepted: 11/12/2014] [Indexed: 12/29/2022]
Abstract
Mutations in the epidermal growth factor receptor (EGFR) kinase domain occur in 10-30% of lung adenocarcinoma and are associated with tyrosine kinase inhibitor (TKI) sensitivity. We sought to identify the immediate direct and indirect phosphorylation targets of mutant EGFRs in lung adenocarcinoma. We undertook SILAC strategy, phosphopeptide enrichment, and quantitative MS to identify dynamic changes of phosphorylation downstream of mutant EGFRs in lung adenocarcinoma cells harboring EGFR(L858R) and EGFR(L858R/T790M) , the TKI-sensitive, and TKI-resistant mutations, respectively. Top canonical pathways that were inhibited upon erlotinib treatment in sensitive cells, but not in the resistant cells include EGFR, insulin receptor, hepatocyte growth factor, mitogen-activated protein kinase, mechanistic target of rapamycin, ribosomal protein S6 kinase beta 1, and Janus kinase/signal transducer and activator of transcription signaling. We identified phosphosites in proteins of the autophagy network, such as ULK1 (S623) that is constitutively phosphorylated in these lung adenocarcinoma cells; phosphorylation is inhibited upon erlotinib treatment in sensitive cells, but not in resistant cells. Finally, kinase-substrate prediction analysis from our data indicated that substrates of basophilic kinases from, AGC and Calcium and calmodulin-dependent kinase groups, as well as STE group kinases were significantly enriched and those of proline-directed kinases from, CMGC and Casein kinase groups were significantly depleted among substrates that exhibited increased phosphorylation upon EGF stimulation and reduced phosphorylation upon TKI inhibition. This is the first study to date to examine global phosphorylation changes upon erlotinib treatment of lung adenocarcinoma cells and results from this study provide new insights into signaling downstream of mutant EGFRs in lung adenocarcinoma. All MS data have been deposited in the ProteomeXchange with identifier PXD001101 (http://proteomecentral.proteomexchange.org/dataset/PXD001101).
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Affiliation(s)
- Xu Zhang
- Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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Zi Z, Zhang Z, Li Q, An W, Zeng L, Gao D, Yang Y, Zhu X, Zeng R, Shum WW, Wu J. CCNYL1, but Not CCNY, Cooperates with CDK16 to Regulate Spermatogenesis in Mouse. PLoS Genet 2015; 11:e1005485. [PMID: 26305884 PMCID: PMC4549061 DOI: 10.1371/journal.pgen.1005485] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/05/2015] [Indexed: 11/18/2022] Open
Abstract
Cyclin Y-like 1 (Ccnyl1) is a newly-identified member of the cyclin family and is highly similar in protein sequences to Cyclin Y (Ccny). However, the function of Ccnyl1 is poorly characterized in any organism. Here we found that Ccnyl1 was most abundantly expressed in the testis of mice and was about seven times higher than the level of Ccny. Male Ccnyl1-/- mice were infertile, whereas both male and female Ccny-/- mice displayed normal fertility. These results suggest that Ccnyl1, but not Ccny, is indispensable for male fertility. Spermatozoa obtained from Ccnyl1-/- mice displayed significantly impaired motility, and represented a thinned annulus region and/or a bent head. We found that the protein, but not the mRNA, level of cyclin-dependent kinase 16 (CDK16) was decreased in the testis of Ccnyl1-/- mice. Further study demonstrated that CCNYL1 interacted with CDK16 and this interaction mutually increased the stability of these two proteins. Moreover, the interaction increased the kinase activity of CDK16. In addition, we observed an alteration of phosphorylation levels of CDK16 in the presence of CCNYL1. We identified the phosphorylation sites of CDK16 by mass spectrometry and revealed that several phosphorylation modifications on the N-terminal region of CDK16 were indispensable for the CCNYL1 binding and the modulation of CDK16 kinase activity. Our results therefore reveal a previously unrecognized role of CCNYL1 in regulating spermatogenesis through the interaction and modulation of CDK16. Infertility is a global public health issue that affects up to 15% of reproductive-age couples worldwide, and male infertility contributes to about 50% of these cases. However, our knowledge of the genetic causes of infertility is still limited. Nowadays, the knockout or mutant animal models have become valuable tools for identifying dysfunctional genes in the infertile population. Here, we show that CCNYL1 is specifically and highly expressed in the testis and mainly localized on the plasma membrane of spermatocytes and spermatids. Using the Ccnyl1 knockout model, we found that male but not female Ccnyl1-/- mice were infertile, accompanied by sperm defects in both motility and structural integrity. Most cyclins are known to function by forming complexes with CDKs, and our study shows for the first time that the partner for CCNYL1 is CDK16. We found that the interaction between CCNYL1 and CDK16 was indispensable for the stability and activity of CDK16. Phosphorylation modifications on CDK16 were also involved in this process. Our study thus reveals an important role of CCNYL1 in regulating male mouse fertility by cooperating with CDK16 and provides insights into the mechanisms underlying cases of male infertility with similar phenotypes.
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Affiliation(s)
- Zhenzhen Zi
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science & Technology of China, Hefei, Anhui, China
| | - Zhuzhen Zhang
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qingrun Li
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Weiwei An
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Liyong Zeng
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Dayuan Gao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ying Yang
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Rong Zeng
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Winnie Waichi Shum
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail: (WWS); (JW)
| | - Jiarui Wu
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science & Technology of China, Hefei, Anhui, China
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
- * E-mail: (WWS); (JW)
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29
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Marttinen M, Kurkinen KM, Soininen H, Haapasalo A, Hiltunen M. Synaptic dysfunction and septin protein family members in neurodegenerative diseases. Mol Neurodegener 2015; 10:16. [PMID: 25888325 PMCID: PMC4391194 DOI: 10.1186/s13024-015-0013-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/23/2015] [Indexed: 11/10/2022] Open
Abstract
Cognitive decline and disease progression in different neurodegenerative diseases typically involves synaptic dysfunction preceding the neuronal loss. The synaptic dysfunction is suggested to be caused by imbalanced synaptic plasticity i.e. enhanced induction of long-term depression and concomitantly decreased long-term potentiation accompanied with excess stimulation of extrasynaptic N-Methyl-D-aspartate (NMDA) receptors due to various disturbances in pre- and postsynaptic sites. Recent research has identified neurodegenerative disease-related changes in protein accumulation and aggregation, gene expression, and protein functions, which may contribute to imbalanced synaptic function. Nevertheless, a comprehensive understanding of the mechanisms regulating synaptic plasticity in health and disease is still lacking and therefore characterization of new candidates involved in these mechanisms is needed. Septins, a highly conserved group of guanosine-5'-triphosphate (GTP)-binding proteins, show high neuronal expression and are implicated in the regulation of synaptic vesicle trafficking and neurotransmitter release. In this review, we first summarize the evidence how synaptic dysfunction is related to the pathogenesis of Alzheimer's, Parkinson's and Huntington's disease and frontotemporal lobar degeneration. Then, we discuss different aspects of the potential involvement of the septin family members in the regulation of synaptic function in relation to the pathogenesis of neurodegenerative diseases.
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Affiliation(s)
- Mikael Marttinen
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland. .,Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Kaisa Ma Kurkinen
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland. .,Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Hilkka Soininen
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Mikko Hiltunen
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland. .,Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
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30
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Tokhtaeva E, Capri J, Marcus EA, Whitelegge JP, Khuzakhmetova V, Bukharaeva E, Deiss-Yehiely N, Dada LA, Sachs G, Fernandez-Salas E, Vagin O. Septin dynamics are essential for exocytosis. J Biol Chem 2015; 290:5280-97. [PMID: 25575596 DOI: 10.1074/jbc.m114.616201] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Septins are a family of 14 cytoskeletal proteins that dynamically form hetero-oligomers and organize membrane microdomains for protein complexes. The previously reported interactions with SNARE proteins suggested the involvement of septins in exocytosis. However, the contradictory results of up- or down-regulation of septin-5 in various cells and mouse models or septin-4 in mice suggested either an inhibitory or a stimulatory role for these septins in exocytosis. The involvement of the ubiquitously expressed septin-2 or general septin polymerization in exocytosis has not been explored to date. Here, by nano-LC with tandem MS and immunoblot analyses of the septin-2 interactome in mouse brain, we identified not only SNARE proteins but also Munc-18-1 (stabilizes assembled SNARE complexes), N-ethylmaleimide-sensitive factor (NSF) (disassembles SNARE complexes after each membrane fusion event), and the chaperones Hsc70 and synucleins (maintain functional conformation of SNARE proteins after complex disassembly). Importantly, α-soluble NSF attachment protein (SNAP), the adaptor protein that mediates NSF binding to the SNARE complex, did not interact with septin-2, indicating that septins undergo reorganization during each exocytosis cycle. Partial depletion of septin-2 by siRNA or impairment of septin dynamics by forchlorfenuron inhibited constitutive and stimulated exocytosis of secreted and transmembrane proteins in various cell types. Forchlorfenuron impaired the interaction between SNAP-25 and its chaperone Hsc70, decreasing SNAP-25 levels in cultured neuroendocrine cells, and inhibited both spontaneous and stimulated acetylcholine secretion in mouse motor neurons. The results demonstrate a stimulatory role of septin-2 and the dynamic reorganization of septin oligomers in exocytosis.
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Affiliation(s)
- Elmira Tokhtaeva
- From the Departments of Physiology and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073
| | - Joe Capri
- The Neuropsychiatric Institute-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California 90024
| | - Elizabeth A Marcus
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073, Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California 90095
| | - Julian P Whitelegge
- The Neuropsychiatric Institute-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California 90024
| | - Venera Khuzakhmetova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences, Kazan 420111, Russia, Kazan Federal University, Kazan 420008, Russia
| | - Ellya Bukharaeva
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences, Kazan 420111, Russia, Kazan Federal University, Kazan 420008, Russia
| | - Nimrod Deiss-Yehiely
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and
| | - Laura A Dada
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and
| | - George Sachs
- From the Departments of Physiology and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073
| | - Ester Fernandez-Salas
- Department of Pathology, School of Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Olga Vagin
- From the Departments of Physiology and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073,
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Wesseling H, Gottschalk MG, Bahn S. Targeted multiplexed selected reaction monitoring analysis evaluates protein expression changes of molecular risk factors for major psychiatric disorders. Int J Neuropsychopharmacol 2014; 18:pyu015. [PMID: 25539505 PMCID: PMC4368865 DOI: 10.1093/ijnp/pyu015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Extensive research efforts have generated genomic, transcriptomic, proteomic, and functional data hoping to elucidate psychiatric pathophysiology. Selected reaction monitoring, a recently developed targeted proteomic mass spectrometric approach, has made it possible to evaluate previous findings and hypotheses with high sensitivity, reproducibility, and quantitative accuracy. METHODS Here, we have developed a labelled multiplexed selected reaction monitoring assay, comprising 56 proteins previously implicated in the aetiology of major psychiatric disorders, including cell type markers or targets and effectors of known psychopharmacological interventions. We analyzed postmortem anterior prefrontal cortex (Brodmann area 10) tissue of patients diagnosed with schizophrenia (n=22), bipolar disorder (n=23), and major depressive disorder with (n=11) and without (n=11) psychotic features compared with healthy controls (n=22). RESULTS Results agreed with several previous studies, with the finding of alterations of Wnt-signalling and glutamate receptor abundance predominately in bipolar disorder and abnormalities in energy metabolism across the neuropsychiatric disease spectrum. Calcium signalling was predominantly affected in schizophrenia and affective psychosis. Interestingly, we were able to show a decrease of all 4 tested oligodendrocyte specific proteins (MOG, MBP, MYPR, CNPase) in bipolar disorder and to a lesser extent in schizophrenia and affective psychosis. Finally, we provide new evidence linking ankyrin 3 specifically to affective psychosis and the 22q11.2 deletion syndrome-associated protein septin 5 to schizophrenia. CONCLUSIONS Our study highlights the potential of selected reaction monitoring to evaluate the protein abundance levels of candidate markers of neuropsychiatric spectrum disorders, providing a high throughput multiplex platform for validation of putative disease markers and drug targets.
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Affiliation(s)
| | | | - Sabine Bahn
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom (Wesseling, Gottschalk, and Bahn); Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands (Dr Bahn).H.W. and M.G.G. contributed equally to this work.
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32
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Septins arrange F-actin-containing fibers on the Chlamydia trachomatis inclusion and are required for normal release of the inclusion by extrusion. mBio 2014; 5:e01802-14. [PMID: 25293760 PMCID: PMC4196233 DOI: 10.1128/mbio.01802-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular human pathogen that grows inside a membranous, cytosolic vacuole termed an inclusion. Septins are a group of 13 GTP-binding proteins that assemble into oligomeric complexes and that can form higher-order filaments. We report here that the septins SEPT2, -9, -11, and probably -7 form fibrillar structures around the chlamydial inclusion. Colocalization studies suggest that these septins combine with F actin into fibers that encase the inclusion. Targeting the expression of individual septins by RNA interference (RNAi) prevented the formation of septin fibers as well as the recruitment of actin to the inclusion. At the end of the developmental cycle of C. trachomatis, newly formed, infectious elementary bodies are released, and this release occurs at least in part through the organized extrusion of intact inclusions. RNAi against SEPT9 or against the combination of SEPT2/7/9 substantially reduced the number of extrusions from a culture of infected HeLa cells. The data suggest that a higher-order structure of four septins is involved in the recruitment or stabilization of the actin coat around the chlamydial inclusion and that this actin recruitment by septins is instrumental for the coordinated egress of C. trachomatis from human cells. The organization of F actin around parasite-containing vacuoles may be a broader response mechanism of mammalian cells to the infection by intracellular, vacuole-dwelling pathogens. Chlamydia trachomatis is a frequent bacterial pathogen throughout the world, causing mostly eye and genital infections. C. trachomatis can develop only inside host cells; it multiplies inside a membranous vacuole in the cytosol, termed an inclusion. The inclusion is covered by cytoskeletal “coats” or “cages,” whose organization and function are poorly understood. We here report that a relatively little-characterized group of proteins, septins, is required to organize actin fibers on the inclusion and probably through actin the release of the inclusion. Septins are a group of GTP-binding proteins that can organize into heteromeric complexes and then into large filaments. Septins have previously been found to be involved in the interaction of the cell with bacteria in the cytosol. Our observation that they also organize a reaction to bacteria living in vacuoles suggests that they have a function in the recognition of foreign compartments by a parasitized human cell.
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Phosphorylation of synapsin I by cyclin-dependent kinase-5 sets the ratio between the resting and recycling pools of synaptic vesicles at hippocampal synapses. J Neurosci 2014; 34:7266-80. [PMID: 24849359 DOI: 10.1523/jneurosci.3973-13.2014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cyclin-dependent kinase-5 (Cdk5) was reported to downscale neurotransmission by sequestering synaptic vesicles (SVs) in the release-reluctant resting pool, but the molecular targets mediating this activity remain unknown. Synapsin I (SynI), a major SV phosphoprotein involved in the regulation of SV trafficking and neurotransmitter release, is one of the presynaptic substrates of Cdk5, which phosphorylates it in its C-terminal region at Ser(549) (site 6) and Ser(551) (site 7). Here we demonstrate that Cdk5 phosphorylation of SynI fine tunes the recruitment of SVs to the active recycling pool and contributes to the Cdk5-mediated homeostatic responses. Phosphorylation of SynI by Cdk5 is physiologically regulated and enhances its binding to F-actin. The effects of Cdk5 inhibition on the size and depletion kinetics of the recycling pool, as well as on SV distribution within the nerve terminal, are virtually abolished in mouse SynI knock-out (KO) neurons or in KO neurons expressing the dephosphomimetic SynI mutants at sites 6,7 or site 7 only. The observation that the single site-7 mutant phenocopies the effects of the deletion of SynI identifies this site as the central switch in mediating the synaptic effects of Cdk5 and demonstrates that SynI is necessary and sufficient for achieving the effects of the kinase on SV trafficking. The phosphorylation state of SynI by Cdk5 at site 7 is regulated during chronic modification of neuronal activity and is an essential downstream effector for the Cdk5-mediated homeostatic scaling.
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Vagin O, Tokhtaeva E, Garay PE, Souda P, Bassilian S, Whitelegge JP, Lewis R, Sachs G, Wheeler L, Aoki R, Fernandez-Salas E. Recruitment of septin cytoskeletal proteins by botulinum toxin A protease determines its remarkable stability. J Cell Sci 2014; 127:3294-308. [PMID: 24928902 DOI: 10.1242/jcs.146324] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Proteolytic cleavage of synaptosomal-associated protein 25 by the light chain of botulinum neurotoxin type A (LCA) results in a blockade of neurotransmitter release that persists for several months in motor neurons. The L428A/L429A mutation in LCA is known to significantly shorten both the proteolytic and neuroparalytic effects of the neurotoxin in mice. To elucidate the cellular mechanism for LCA longevity, we studied the effects of L428A/L429A mutation on the interactome, localization and stability of LCA expressed in cultured neuronal cells. Mass spectrometry analysis of the LCA interactome showed that the mutation prevented the interaction of LCA with septins. The wild-type LCA was concentrated in plasma-membrane-associated clusters, colocalizing with septins-2 and septin-7, which accumulated in these clusters only in the presence of LCA. The L428A/L429A mutation decreased co-clustering of LCA and septins and accelerated proteasomal and non-proteasomal degradation of LCA. Similarly, the impairment of septin oligomerization by forchlorfenuron or silencing of septin-2 prevented LCA interaction and clustering with septins and increased LCA degradation. Therefore, the dileucine-mediated LCA-septin co-clustering is crucial for the long-lasting stabilization of LCA-related proteolytic and presumably neuroparalytic activity.
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Affiliation(s)
- Olga Vagin
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, CA 91343, USA
| | - Elmira Tokhtaeva
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, CA 91343, USA
| | - Patton E Garay
- Department of Biological Sciences, Allergan Inc., Irvine, CA 92612, USA
| | - Puneet Souda
- The NPI-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, CA 90095, USA
| | - Sara Bassilian
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, CA 91343, USA
| | - Julian P Whitelegge
- The NPI-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, CA 90095, USA
| | - Ramilla Lewis
- Department of Biological Sciences, Allergan Inc., Irvine, CA 92612, USA
| | - George Sachs
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, CA 91343, USA
| | - Larry Wheeler
- Department of Biological Sciences, Allergan Inc., Irvine, CA 92612, USA
| | - Roger Aoki
- Department of Biological Sciences, Allergan Inc., Irvine, CA 92612, USA
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Estey MP, Di Ciano-Oliveira C, Froese CD, Fung KYY, Steels JD, Litchfield DW, Trimble WS. Mitotic regulation of SEPT9 protein by cyclin-dependent kinase 1 (Cdk1) and Pin1 protein is important for the completion of cytokinesis. J Biol Chem 2013; 288:30075-30086. [PMID: 23990466 DOI: 10.1074/jbc.m113.474932] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Precise cell division is essential for multicellular development, and defects in this process have been linked to cancer. Septins are a family of proteins that are required for mammalian cell division, but their function and mode of regulation during this process are poorly understood. Here, we demonstrate that cyclin-dependent kinase 1 (Cdk1) phosphorylates septin 9 (SEPT9) upon mitotic entry, and this phosphorylation controls association with the proline isomerase, Pin1. Both SEPT9 and Pin1 are critical for mediating the final separation of daughter cells. Expression of mutant SEPT9 that is defective in Pin1 binding was unable to rescue cytokinesis defects caused by SEPT9 depletion but rather induced dominant-negative defects in cytokinesis. However, unlike SEPT9 depletion, Pin1 was not required for the accumulation of the exocyst complex at the midbody. These results suggest that SEPT9 plays multiple roles in abscission, one of which is regulated by the action of Cdk1 and Pin1.
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Affiliation(s)
- Mathew P Estey
- From the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada,; the Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and
| | | | - Carol D Froese
- the Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and
| | - Karen Y Y Fung
- From the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada,; the Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and
| | - Jonathan D Steels
- From the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada,; the Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and
| | - David W Litchfield
- the Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - William S Trimble
- From the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada,; the Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and.
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Su J, Chow B, Boulianne GL, Wilde A. The BAR domain of amphiphysin is required for cleavage furrow tip-tubule formation during cellularization in Drosophila embryos. Mol Biol Cell 2013; 24:1444-53. [PMID: 23447705 PMCID: PMC3639055 DOI: 10.1091/mbc.e12-12-0878] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
De novo formation of cells in the Drosophila embryo is achieved when each nucleus is surrounded by a furrow of plasma membrane. Remodeling of the plasma membrane during cleavage furrow ingression involves the exocytic and endocytic pathways, including endocytic tubules that form at cleavage furrow tips (CFT-tubules). The tubules are marked by amphiphysin but are otherwise poorly understood. Here we identify the septin family of GTPases as new tubule markers. Septins do not decorate CFT-tubules homogeneously: instead, novel septin complexes decorate different CFT-tubules or different domains of the same CFT-tubule. Using these new tubule markers, we determine that all CFT-tubule formation requires the BAR domain of amphiphysin. In contrast, dynamin activity is preferentially required for the formation of the subset of CFT-tubules containing the septin Peanut. The absence of tubules in amphiphysin-null embryos correlates with faster cleavage furrow ingression rates. In contrast, upon inhibition of dynamin, longer tubules formed, which correlated with slower cleavage furrow ingression rates. These data suggest that regulating the recycling of membrane within the embryo is important in supporting timely furrow ingression.
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Affiliation(s)
- Jing Su
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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Lu L, Gao X, Li Q, Huang J, Liu R, Li H. Comparative phosphoproteomics analysis of the effects of L-methionine on dairy cow mammary epithelial cells. CANADIAN JOURNAL OF ANIMAL SCIENCE 2012. [DOI: 10.4141/cjas2012-063] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lu, L., Gao, X., Li, Q., Huang, J., Liu, R. and Li, H. 2012. Comparative phosphoproteomics analysis of the effects of L-methionine on dairy cow mammary epithelial cells. Can. J. Anim. Sci. 92: 433–442. L-methionine is an essential amino acid that plays fundamental roles in protein synthesis. Many nuclear phosphorylated proteins such as Stat5 (signal transducer and activator of transcription 5) and mTOR (mammalian target of rapamycin) regulate milk protein synthesis. But a comprehensive understanding of transcriptional and posttranscriptional regulation of milk protein synthesis is lacking. In the current study, two-dimensional gel electrophoresis (2-DE)/MS-based proteomics analysis was used to identify phosphoproteins responsible for milk protein synthesis in dairy cow mammary epithelial cells (DCMECs). The effects of L-methionine on DCMECs were analyzed by CASY (Counter Analyser System) technique, reversed phase high performance liquid chromatography. The results showed that rate of cell proliferation and expression of β-casein were increased in DCMECs treated with 0.6 mM L-methionine for 24 h. Five proteins for which expression was significantly increased in DCMECs were selected, and their expression changes were verified by quantitative real-time PCR and Western blot analysis. The five up-regulated expressed phosphoproteins included Staphylococcal nuclease domain-containing protein 1(SND1), Septin-6, Glycyl-tRNA synthetase (GARS), Twinfilin-1 and eukaryotic elongation factor1-beta (eEF1B). This study revealed that availability of L-methionine influences the levels of nuclear phosphorylated proteins of DCMECs which opens a new avenue for the study of the molecular mechanism linking to milk protein synthesis.
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Affiliation(s)
- Limin Lu
- The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, China
| | - Xuejun Gao
- The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, China
| | - Qingzhang Li
- The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, China
| | - Jianguo Huang
- The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, China
| | - Rong Liu
- The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, China
| | - Huiming Li
- The Key Laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, China
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Septin phosphorylation and coiled-coil domains function in cell and septin ring morphology in the filamentous fungus Ashbya gossypii. EUKARYOTIC CELL 2012. [PMID: 23204191 DOI: 10.1128/ec.00251-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Septins are a class of GTP-binding proteins conserved throughout many eukaryotes. Individual septin subunits associate with one another and assemble into heteromeric complexes that form filaments and higher-order structures in vivo. The mechanisms underlying the assembly and maintenance of higher-order structures in cells remain poorly understood. Septins in several organisms have been shown to be phosphorylated, although precisely how septin phosphorylation may be contributing to the formation of high-order septin structures is unknown. Four of the five septins expressed in the filamentous fungus, Ashbya gossypii, are phosphorylated, and we demonstrate here the diverse roles of these phosphorylation sites in septin ring formation and septin dynamics, as well as cell morphology and viability. Intriguingly, the alteration of specific sites in Cdc3p and Cdc11p leads to a complete loss of higher-order septin structures, implicating septin phosphorylation as a regulator of septin structure formation. Introducing phosphomimetic point mutations to specific sites in Cdc12p and Shs1p causes cell lethality, highlighting the importance of normal septin modification in overall cell function and health. In addition to discovering roles for phosphorylation, we also present diverse functions for conserved septin domains in the formation of septin higher-order structure. We previously showed the requirement for the Shs1p coiled-coil domain in limiting septin ring size and reveal here that, in contrast to Shs1p, the coiled-coil domains of Cdc11p and Cdc12p are required for septin ring formation. Our results as a whole reveal novel roles for septin phosphorylation and coiled-coil domains in regulating septin structure and function.
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Chronic hyperdopaminergic activity of schizophrenia is associated with increased ΔFosB levels and cdk-5 signaling in the nucleus accumbens. Neuroscience 2012; 222:124-35. [DOI: 10.1016/j.neuroscience.2012.07.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 07/10/2012] [Accepted: 07/12/2012] [Indexed: 11/18/2022]
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MacDonald ML, Ciccimaro E, Prakash A, Banerjee A, Seeholzer SH, Blair IA, Hahn CG. Biochemical fractionation and stable isotope dilution liquid chromatography-mass spectrometry for targeted and microdomain-specific protein quantification in human postmortem brain tissue. Mol Cell Proteomics 2012; 11:1670-81. [PMID: 22942359 DOI: 10.1074/mcp.m112.021766] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Synaptic architecture and its adaptive changes require numerous molecular events that are both highly ordered and complex. A majority of neuropsychiatric illnesses are complex trait disorders, in which multiple etiologic factors converge at the synapse via many signaling pathways. Investigating the protein composition of synaptic microdomains from human patient brain tissues will yield valuable insights into the interactions of risk genes in many disorders. These types of studies in postmortem tissues have been limited by the lack of proper study paradigms. Thus, it is necessary not only to develop strategies to quantify protein and post-translational modifications at the synapse, but also to rigorously validate them for use in postmortem human brain tissues. In this study we describe the development of a liquid chromatography-selected reaction monitoring method, using a stable isotope-labeled neuronal proteome standard prepared from the brain tissue of a stable isotope-labeled mouse, for the multiplexed quantification of target synaptic proteins in mammalian samples. Additionally, we report the use of this method to validate a biochemical approach for the preparation of synaptic microdomain enrichments from human postmortem prefrontal cortex. Our data demonstrate that a targeted mass spectrometry approach with a true neuronal proteome standard facilitates accurate and precise quantification of over 100 synaptic proteins in mammalian samples, with the potential to quantify over 1000 proteins. Using this method, we found that protein enrichments in subcellular fractions prepared from human postmortem brain tissue were strikingly similar to those prepared from fresh mouse brain tissue. These findings demonstrate that biochemical fractionation methods paired with targeted proteomic strategies can be used in human brain tissues, with important implications for the study of neuropsychiatric disease.
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Affiliation(s)
- Matthew L MacDonald
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Meseroll RA, Howard L, Gladfelter AS. Septin ring size scaling and dynamics require the coiled-coil region of Shs1p. Mol Biol Cell 2012; 23:3391-406. [PMID: 22767579 PMCID: PMC3431940 DOI: 10.1091/mbc.e12-03-0207] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
How the size and dynamics of higher-order septin structures is determined is not well understood in any system. In this paper, we show that the coiled-coil domain of the septin Shs1p limits septin ring size and dynamics in the filamentous fungus Ashbya gossypii, providing a link between protein exchange and the scaling of septin assemblies. Septins are conserved GTP-binding proteins that assemble into heteromeric complexes that form filaments and higher-order structures in cells. What directs filament assembly, determines the size of higher-order septin structures, and governs septin dynamics is still not well understood. We previously identified two kinases essential for septin ring assembly in the filamentous fungus Ashbya gossypii and demonstrate here that the septin Shs1p is multiphosphorylated at the C-terminus of the protein near the predicted coiled-coil domain. Expression of the nonphosphorylatable allele shs1-9A does not mimic the loss of the kinase nor does complete truncation of the Shs1p C-terminus. Surprisingly, however, loss of the C-terminus or the predicted coiled-coil domain of Shs1p generates expanded zones of septin assemblies and ectopic septin fibers, as well as aberrant cell morphology. The expanded structures form coincident with ring assembly and are heteromeric. Interestingly, while septin recruitment to convex membranes is increased, septin localization is diminished at concave membranes in these mutants. Additionally, the loss of the coiled-coil leads to increased mobility of Shs1p. These data indicate the coiled-coil of Shs1p is an important negative regulator of septin ring size and mobility, and its absence may make septin assembly sensitive to local membrane curvature.
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Affiliation(s)
- Rebecca A Meseroll
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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Shiryaev A, Kostenko S, Dumitriu G, Moens U. Septin 8 is an interaction partner and in vitro substrate of MK5. World J Biol Chem 2012; 3:98-109. [PMID: 22649572 PMCID: PMC3362842 DOI: 10.4331/wjbc.v3.i5.98] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/09/2012] [Accepted: 03/16/2012] [Indexed: 02/05/2023] Open
Abstract
AIM: To identify novel substrates for the mitogen-activated protein kinase-activated protein kinase 5 (MK5).
METHODS: Yeast two-hybrid screening with MK5 as bait was used to identify novel possible interaction partners. The binding of putative partner was further examined by glutathione S-transferase (GST) pull-down, co-immunoprecipitation and fluorescence resonance energy transfer (FRET) analysis. In vitro kinase and peptide array assays were used to map MK5 phosphoacceptor sites on the new partner. Confocal microscopy was performed to study the subcellular localization of MK5 and its partners.
RESULTS: Septin 8 was identified as a novel interaction partner for MK5 by yeast two-hybrid screening. This interaction was confirmed by GST pull-down, co-immunoprecipitation and FRET analysis. Septin 5, which can form a complex with septin 8, did not interact with MK5. Serine residues 242 and 271 on septin 8 were identified as in vitro MK5 phosphorylation sites. MK5 and septin 8 co-localized in the perinuclear area and in cell protrusions. Moreover, both proteins co-localized with vesicle marker synaptophysin.
CONCLUSION: Septin 8 is a bona fide interaction partner and in vitro substrate for MK5. This interaction may be implicated in vesicle trafficking.
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Affiliation(s)
- Alexey Shiryaev
- Alexey Shiryaev, Sergiy Kostenko, Gianina Dumitriu, Ugo Moens, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, N-9037 Tromsø, Norway
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Yoshida A, Yamamoto N, Kinoshita M, Hiroi N, Hiramoto T, Kang G, Trimble WS, Tanigaki K, Nakagawa T, Ito J. Localization of septin proteins in the mouse cochlea. Hear Res 2012; 289:40-51. [PMID: 22575789 DOI: 10.1016/j.heares.2012.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 04/21/2012] [Accepted: 04/23/2012] [Indexed: 11/30/2022]
Abstract
Septins are a family of GTP binding proteins that are well conserved in eukaryotic species except plants. Septins contribute to the lateral compartmentalization of membranes, cortical rigidity, and the regulation of membrane trafficking by associating with membrane lipids, actin, and microtubules. The organ of Corti in the cochlea has pivotal roles in auditory perception and includes two kinds of highly polarized cells, hair and supporting cells, both of which are rich in actin and microtubules. To identify the roles of septins in the cochlea, we analyzed the localization of three septin proteins, septin 4 (SEPT4), septin 5 (SEPT5), and septin 7 (SEPT7) that are abundantly expressed in brain tissues, and also examined auditory functions of Sept4 and Sept5 null mice. SEPT4, SEPT5, and SEPT7 were expressed in inner and outer pillar cells and Deiters' cells but the distribution patterns of each protein in Deiters' cells were different. SEPT4 and SEPT7 were expressed in the phalangeal process where SEPT5 was not detected. In addition to these cells SEPT5 and SEPT7 were co-localized with presynaptic vesicles of efferent nerve terminals. Only SEPT7 was expressed in the cochlea at embryonic stages. Although expression patterns of septin proteins suggested their important roles in the function of the cochlea, both Sept4 and Sept5 null mice had similar auditory functions to their wild type littermates. Immunohistochemical analysis of Sept4 null mice showed that compensatory expression of SEPT5 in the phalangeal process of Deiters' cells may have caused functional compensation of hearing ability in Sept4 null mice.
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Affiliation(s)
- Atsuhiro Yoshida
- Department of Otolaryngology Head and Neck Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto City, Kyoto 606-8507, Japan
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Abstract
Septins belong to a family of proteins that is highly conserved in eukaryotes and is increasingly recognized as a novel component of the cytoskeleton. All septins are GTP-binding proteins that form hetero-oligomeric complexes and higher-order structures, including filaments and rings. Recent studies have provided structural information about the different levels of septin organization; however, the crucial structural determinants and factors responsible for septin assembly remain unclear. Investigations on the molecular functions of septins have highlighted their roles as scaffolds for protein recruitment and as diffusion barriers for subcellular compartmentalization in numerous biological processes, including cell division and host-microorganism interactions.
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Cyclin-dependent kinase 16/PCTAIRE kinase 1 is activated by cyclin Y and is essential for spermatogenesis. Mol Cell Biol 2011; 32:868-79. [PMID: 22184064 DOI: 10.1128/mcb.06261-11] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cyclin-dependent kinase 16 (CDK16, PCTK1) is a poorly characterized protein kinase, highly expressed in the testis and the brain. Here, we report that CDK16 is activated by membrane-associated cyclin Y (CCNY). Treatment of transfected human cells with the protein kinase A (PKA) activator forskolin blocked, while kinase inhibition promoted, CCNY-dependent targeting of CDK16-green fluorescent protein (GFP) to the cell membrane. CCNY binding to CDK16 required a region upstream of the kinase domain and was found to be inhibited by phosphorylation of serine 153, a potential PKA phosphorylation site. Thus, in contrast to other CDKs, CDK16 is regulated by phosphorylation-controlled cyclin binding. CDK16 isolated from murine testis was unphosphorylated, interacted with CCNY, and exhibited kinase activity. To investigate the function of CDK16 in vivo, we established a conditional knockout allele. Mice lacking CDK16 developed normally, but male mice were infertile. Spermatozoa isolated from their epididymis displayed thinning and elongation of the annulus region, adopted a bent shape, and showed impaired motility. Moreover, CDK16-deficient spermatozoa had malformed heads and excess residual cytoplasm, suggesting a role of CDK16 in spermiation. Thus, CDK16 is a membrane-targeted CDK essential for spermatogenesis.
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The emerging functions of septins in metazoans. EMBO Rep 2011; 12:1118-26. [PMID: 21997296 DOI: 10.1038/embor.2011.193] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 09/05/2011] [Indexed: 01/19/2023] Open
Abstract
Septins form a subfamily of highly related GTP-binding proteins conserved from eukaryotic protists to mammals. In most cases, septins function in close association with cell membranes and the actin and microtubule cytoskeleton to regulate a wide variety of key cellular processes. Further underscoring their importance, septin abnormalities are associated with several human diseases. Remarkably, septins have the ability to polymerize into assemblies of different sizes in vitro and in vivo. In cells, these structures act in the formation of diffusion barriers and scaffolds that maintain subcellular polarity. Here, we focus on the emerging roles of vertebrate septins in ciliogenesis, neurogenesis, tumorigenesis and host-pathogen interactions, and discuss whether unifying themes underlie the molecular function of septins in health and disease.
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Septin structure and function in yeast and beyond. Trends Cell Biol 2010; 21:141-8. [PMID: 21177106 DOI: 10.1016/j.tcb.2010.11.006] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 11/04/2010] [Accepted: 11/15/2010] [Indexed: 12/30/2022]
Abstract
Septins are conserved GTP-binding proteins that assemble into hetero-oligomeric complexes and higher-order structures such as filaments, rings, hourglasses or gauzes. Septins are usually associated with a discrete region of the plasma membrane and function as a cell scaffold or diffusion barrier to effect cytokinesis, cell polarity, and many other functions. Recent structural studies of septin complexes have provided mechanistic insights into septin filament assembly, but key questions concerning the assembly, dynamics, and function of different septin structures remain to be answered.
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Abstract
CDK5 is an important kinase in nervous system function, controlling neural development and postsynaptic signal integration. Here we show that CDK5 plays a major role in controlling neurotransmitter release. Inhibition of CDK5 activity, by either acute or genetic means, leads to profound potentiation of presynaptic function, including unmasking of previously "silent" synapses. Removal of CDK5 activity additionally unlocks access to the resting synaptic vesicle pool, which normally remains recalcitrant to exocytosis and recycling even following prolonged action potential stimuli. Presynaptic CDK5 levels are additionally severely depleted by chronic neuronal silencing, a treatment that is functionally similar to CDK5 knockdown with regard to presynaptic potentiation. Thus CDK5 appears to be an integral element in presynaptic homeostatic scaling, and the resting vesicle pool appears to provide a potent functional presynaptic homeostatic control parameter. These studies thus pinpoint CDK5 as a major control point for modulation of neurotransmitter release in mammalian neurons.
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Alvarez-Tabarés I, Pérez-Martín J. Septins from the phytopathogenic fungus Ustilago maydis are required for proper morphogenesis but dispensable for virulence. PLoS One 2010; 5:e12933. [PMID: 20885997 PMCID: PMC2946335 DOI: 10.1371/journal.pone.0012933] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 08/31/2010] [Indexed: 01/09/2023] Open
Abstract
Background Septins are a highly conserved family of GTP-binding proteins involved in multiple cellular functions, including cell division and morphogenesis. Studies of septins in fungal cells underpin a clear correlation between septin-based structures and fungal morphology, providing clues to understand the molecular frame behind the varied morphologies found in fungal world. Methodology/Principal Findings Ustilago maydis genome has the ability to encode four septins. Here, using loss-of-function as well as GFP-tagged alleles of these septin genes, we investigated the roles of septins in the morphogenesis of this basidiomycete fungus. We described that septins in U. maydis could assemble into at least three different structures coexisting in the same cell: bud neck collars, band-like structures at the growing tip, and long septin fibers that run from pole to pole near the cell cortex. We also found that in the absence of septins, U. maydis cells lost their elongated shape, became wider at the central region and ended up losing their polarity, pointing to an important role of septins in the morphogenesis of this fungus. These morphological defects were alleviated in the presence of an osmotic stabilizer suggesting that absence of septins affected the proper formation of the cell wall, which was coherent with a higher sensitivity of septin defective cells to drugs that affect cell wall construction as well as exocytosis. As U. maydis is a phytopathogen, we analyzed the role of septins in virulence and found that in spite of the described morphological defects, septin mutants were virulent in corn plants. Conclusions/Significance Our results indicated a major role of septins in morphogenesis in U. maydis. However, in contrast to studies in other fungal pathogens, in which septins were reported to be necessary during the infection process, we found a minor role of septins during corn infection by U. maydis.
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Affiliation(s)
- Isabel Alvarez-Tabarés
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología CSIC, Madrid, Spain
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Zheng YL, Amin ND, Hu YF, Rudrabhatla P, Shukla V, Kanungo J, Kesavapany S, Grant P, Albers W, Pant HC. A 24-residue peptide (p5), derived from p35, the Cdk5 neuronal activator, specifically inhibits Cdk5-p25 hyperactivity and tau hyperphosphorylation. J Biol Chem 2010; 285:34202-12. [PMID: 20720012 DOI: 10.1074/jbc.m110.134643] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of Cdk5-p35 is tightly regulated in the developing and mature nervous system. Stress-induced cleavage of the activator p35 to p25 and a p10 N-terminal domain induces deregulated Cdk5 hyperactivity and perikaryal aggregations of hyperphosphorylated Tau and neurofilaments, pathogenic hallmarks in neurodegenerative diseases, such as Alzheimer disease and amyotrophic lateral sclerosis, respectively. Previously, we identified a 125-residue truncated fragment of p35 called CIP that effectively and specifically inhibited Cdk5-p25 activity and Tau hyperphosphorylation induced by Aβ peptides in vitro, in HEK293 cells, and in neuronal cells. Although these results offer a possible therapeutic approach to those neurodegenerative diseases assumed to derive from Cdk5-p25 hyperactivity and/or Aβ induced pathology, CIP is too large for successful therapeutic regimens. To identify a smaller, more effective peptide, in this study we prepared a 24-residue peptide, p5, spanning CIP residues Lys(245)-Ala(277). p5 more effectively inhibited Cdk5-p25 activity than did CIP in vitro. In neuron cells, p5 inhibited deregulated Cdk5-p25 activity but had no effect on the activity of endogenous Cdk5-p35 or on any related endogenous cyclin-dependent kinases in HEK293 cells. Specificity of p5 inhibition in cortical neurons may depend on the p10 domain in p35, which is absent in p25. Furthermore, we have demonstrated that p5 reduced Aβ(1-42)-induced Tau hyperphosphorylation and apoptosis in cortical neurons. These results suggest that p5 peptide may be a unique and useful candidate for therapeutic studies of certain neurodegenerative diseases.
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Affiliation(s)
- Ya-Li Zheng
- Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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