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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: 6] [Impact Index Per Article: 6.0] [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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2
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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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3
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Laghaei R, Meriney SD. Microphysiological Modeling of the Structure and Function of Neuromuscular Transmitter Release Sites. Front Synaptic Neurosci 2022; 14:917285. [PMID: 35769072 PMCID: PMC9236679 DOI: 10.3389/fnsyn.2022.917285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
The general mechanism of calcium-triggered chemical transmitter release from neuronal synapses has been intensely studied, is well-known, and highly conserved between species and synapses across the nervous system. However, the structural and functional details within each transmitter release site (or active zone) are difficult to study in living tissue using current experimental approaches owing to the small spatial compartment within the synapse where exocytosis occurs with a very rapid time course. Therefore, computer simulations offer the opportunity to explore these microphysiological environments of the synapse at nanometer spatial scales and on a sub-microsecond timescale. Because biological reactions and physiological processes at synapses occur under conditions where stochastic behavior is dominant, simulation approaches must be driven by such stochastic processes. MCell provides a powerful simulation approach that employs particle-based stochastic simulation tools to study presynaptic processes in realistic and complex (3D) geometries using optimized Monte Carlo algorithms to track finite numbers of molecules as they diffuse and interact in a complex cellular space with other molecules in solution and on surfaces (representing membranes, channels and binding sites). In this review we discuss MCell-based spatially realistic models of the mammalian and frog neuromuscular active zones that were developed to study presynaptic mechanisms that control transmitter release. In particular, these models focus on the role of presynaptic voltage-gated calcium channels, calcium sensors that control the probability of synaptic vesicle fusion, and the effects of action potential waveform shape on presynaptic calcium entry. With the development of these models, they can now be used in the future to predict disease-induced changes to the active zone, and the effects of candidate therapeutic approaches.
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Affiliation(s)
- Rozita Laghaei
- Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Stephen D. Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
- *Correspondence: Stephen D. Meriney
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4
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Phatarpekar PV, Overlee BL, Leehan A, Wilton KM, Ham H, Billadeau DD. The septin cytoskeleton regulates natural killer cell lytic granule release. J Cell Biol 2021; 219:152040. [PMID: 32841357 PMCID: PMC7594501 DOI: 10.1083/jcb.202002145] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/26/2020] [Accepted: 07/28/2020] [Indexed: 11/22/2022] Open
Abstract
Natural killer (NK) cell–mediated killing involves the membrane fusion of preformed lytic granules. While the roles of actin and microtubules are well accepted during this process, the function of septins, another cytoskeletal component that associates with actin and microtubules, has not been investigated. Here we show that genetic depletion or pharmacologic stabilization of the septin cytoskeleton significantly inhibited NK cell cytotoxicity. Although the stabilization of septin filaments impaired conjugate formation, depletion of septin proteins had no impact on conjugate formation, lytic granule convergence, or MTOC polarization to the cytotoxic synapse (CS). Interestingly, septins copurify and accumulate near the polarized lytic granules at the CS, where they regulate lytic granule release. Mechanistically, we find that septin 7 interacts with the SNARE protein syntaxin 11 and facilitates its interaction with syntaxin binding protein 2 to promote lytic granule fusion. Altogether, our data identify a critical role for septins in regulating the release of lytic granule contents during NK cell–mediated killing.
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Affiliation(s)
| | - Brittany L Overlee
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN
| | - Alexander Leehan
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN
| | - Katelynn M Wilton
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN
| | - Hyoungjun Ham
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN
| | - Daniel D Billadeau
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN
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Györffy BA, Tóth V, Török G, Gulyássy P, Kovács RÁ, Vadászi H, Micsonai A, Tóth ME, Sántha M, Homolya L, Drahos L, Juhász G, Kékesi KA, Kardos J. Synaptic mitochondrial dysfunction and septin accumulation are linked to complement-mediated synapse loss in an Alzheimer's disease animal model. Cell Mol Life Sci 2020; 77:5243-5258. [PMID: 32034429 PMCID: PMC7671981 DOI: 10.1007/s00018-020-03468-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/25/2019] [Accepted: 01/21/2020] [Indexed: 12/21/2022]
Abstract
Synaptic functional disturbances with concomitant synapse loss represent central pathological hallmarks of Alzheimer's disease. Excessive accumulation of cytotoxic amyloid oligomers is widely recognized as a key event that underlies neurodegeneration. Certain complement components are crucial instruments of widespread synapse loss because they can tag synapses with functional impairments leading to their engulfment by microglia. However, an exact understanding of the affected synaptic functions that predispose to complement-mediated synapse elimination is lacking. Therefore, we conducted systematic proteomic examinations on synaptosomes prepared from an amyloidogenic mouse model of Alzheimer's disease (APP/PS1). Synaptic fractions were separated according to the presence of the C1q-tag using fluorescence-activated synaptosome sorting and subjected to proteomic comparisons. The results raised the decline of mitochondrial functions in the C1q-tagged synapses of APP/PS1 mice based on enrichment analyses, which was verified using flow cytometry. Additionally, proteomics results revealed extensive alterations in the level of septin protein family members, which are known to dynamically form highly organized pre- and postsynaptic supramolecular structures, thereby affecting synaptic transmission. High-resolution microscopy investigations demonstrated that synapses with considerable amounts of septin-3 and septin-5 show increased accumulation of C1q in APP/PS1 mice compared to the wild-type ones. Moreover, a strong positive correlation was apparent between synaptic septin-3 levels and C1q deposition as revealed via flow cytometry and confocal microscopy examinations. In sum, our results imply that deterioration of synaptic mitochondrial functions and alterations in the organization of synaptic septins are associated with complement-dependent synapse loss in Alzheimer's disease.
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Affiliation(s)
- Balázs A Györffy
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Vilmos Tóth
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - György Török
- Molecular Cell Biology Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences Centre of Excellence, Budapest, Hungary
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Péter Gulyássy
- MS Proteomics Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Budapest, Hungary
| | - Réka Á Kovács
- Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Henrietta Vadászi
- Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - András Micsonai
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Melinda E Tóth
- Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Miklós Sántha
- Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - László Homolya
- Molecular Cell Biology Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences Centre of Excellence, Budapest, Hungary
| | - László Drahos
- MS Proteomics Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Budapest, Hungary
| | - Gábor Juhász
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- CRU Hungary Ltd., Göd, Hungary
| | - Katalin A Kékesi
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
- Department of Physiology and Neurobiology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - József Kardos
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary.
- Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary.
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6
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Woods BL, Gladfelter AS. The state of the septin cytoskeleton from assembly to function. Curr Opin Cell Biol 2020; 68:105-112. [PMID: 33188984 DOI: 10.1016/j.ceb.2020.10.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/01/2020] [Accepted: 10/08/2020] [Indexed: 01/09/2023]
Abstract
Septins are conserved guanine nucleotide-binding proteins that polymerize into filaments at the cell cortex or in association with other cytoskeletal proteins, such as actin or microtubules. As integral players in many morphogenic and signaling events, septins form scaffolds important for the recruitment of the cytokinetic machinery, organization of the plasma membrane, and orientation of cell polarity. Mutations in septins or their misregulation are associated with numerous diseases. Despite growing appreciation for the importance of septins in different aspects of cell biology and disease, septins remain relatively poorly understood compared with other cytoskeletal proteins. Here in this review, we highlight some of the recent developments of the last two years in the field of septin cell biology.
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Affiliation(s)
- Benjamin L Woods
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Amy S Gladfelter
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA; Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
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7
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Sun L, Cao X, Lechuga S, Feygin A, Naydenov NG, Ivanov AI. A Septin Cytoskeleton-Targeting Small Molecule, Forchlorfenuron, Inhibits Epithelial Migration via Septin-Independent Perturbation of Cellular Signaling. Cells 2019; 9:cells9010084. [PMID: 31905721 PMCID: PMC7016606 DOI: 10.3390/cells9010084] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/24/2019] [Accepted: 12/26/2019] [Indexed: 12/19/2022] Open
Abstract
Septins are GTP-binding proteins that self-assemble into high-order cytoskeletal structures, filaments, and rings. The septin cytoskeleton has a number of cellular functions, including regulation of cytokinesis, cell migration, vesicle trafficking, and receptor signaling. A plant cytokinin, forchlorfenuron (FCF), interacts with septin subunits, resulting in the altered organization of the septin cytoskeleton. Although FCF has been extensively used to examine the roles of septins in various cellular processes, its specificity, and possible off-target effects in vertebrate systems, has not been investigated. In the present study, we demonstrate that FCF inhibits spontaneous, as well as hepatocyte growth factor-induced, migration of HT-29 and DU145 human epithelial cells. Additionally, FCF increases paracellular permeability of HT-29 cell monolayers. These inhibitory effects of FCF persist in epithelial cells where the septin cytoskeleton has been disassembled by either CRISPR/Cas9-mediated knockout or siRNA-mediated knockdown of septin 7, insinuating off-target effects of FCF. Biochemical analysis reveals that FCF-dependent inhibition of the motility of control and septin-depleted cells is accompanied by decreased expression of the c-Jun transcription factor and inhibited ERK activity. The described off-target effects of FCF strongly suggests that caution is warranted while using this compound to examine the biological functions of septins in cellular systems and model organisms.
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Affiliation(s)
- Lei Sun
- Department of Inflammation and Immunity, Lerner Research Institute of Cleveland Clinic Foundation, Cleveland, OH 44195, USA; (L.S.); (X.C.); (S.L.); (N.G.N.)
| | - Xuelei Cao
- Department of Inflammation and Immunity, Lerner Research Institute of Cleveland Clinic Foundation, Cleveland, OH 44195, USA; (L.S.); (X.C.); (S.L.); (N.G.N.)
| | - Susana Lechuga
- Department of Inflammation and Immunity, Lerner Research Institute of Cleveland Clinic Foundation, Cleveland, OH 44195, USA; (L.S.); (X.C.); (S.L.); (N.G.N.)
| | - Alex Feygin
- School of Nursing, Virginia Commonwealth University School of Nursing, Richmond, VA 23298, USA;
| | - Nayden G. Naydenov
- Department of Inflammation and Immunity, Lerner Research Institute of Cleveland Clinic Foundation, Cleveland, OH 44195, USA; (L.S.); (X.C.); (S.L.); (N.G.N.)
| | - Andrei I. Ivanov
- Department of Inflammation and Immunity, Lerner Research Institute of Cleveland Clinic Foundation, Cleveland, OH 44195, USA; (L.S.); (X.C.); (S.L.); (N.G.N.)
- Correspondence: ; Tel.: +1-216-444-5620
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