1
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Knutson D, Irgens MS, Flynn KC, Norvilitis JM, Bauer LM, Berkessel JB, Cascalheira CJ, Cera JL, Choi NY, Cuccolo K, Danielson DK, Dascano KN, Edlund JE, Fletcher T, Flinn RE, Gosnell CL, Heermans G, Horne M, Howell JL, Hua J, Ijebor EE, Jia F, McGillivray S, Ogba KTU, Shane-Simpson C, Staples A, Ugwu CF, Wang SC, Yockey A, Zheng Z, Zlokovich MS. Associations Between Primary Residence and Mental Health in Global Marginalized Populations. Community Ment Health J 2023; 59:1083-1096. [PMID: 36695952 PMCID: PMC9874180 DOI: 10.1007/s10597-023-01088-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 01/05/2023] [Indexed: 01/26/2023]
Abstract
Scholars suggest that marginalized people in non-urban areas experience higher distress levels and fewer psychosocial resources than in urban areas. Researchers have yet to test whether precise proximity to urban centers is associated with mental health for marginalized populations. We recruited 1733 people who reported living in 45 different countries. Participants entered their home locations and completed measures of anxiety, depression, social support, and resilience. Regression and thematic analyses were used to determine what role distance from legislative and urban centers may play in mental health when marginalized people were disaggregated. Greater distance from legislative center predicted higher anxiety and resilience. Greater distance from urban center also predicted more resilience. Thematic analyses yielded five categories (e.g., safety, connection) that further illustrated the impact of geographic location on health. Implications for community mental health are discussed including the need to better understand and further expand resilience in rural areas.
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Affiliation(s)
- D Knutson
- Oklahoma State University, 445 Willard Hall, Stillwater, OK, 74078, USA.
| | | | - K C Flynn
- United States Department of Agriculture - Agricultural Research Service, Washington, DC, USA
| | | | - L M Bauer
- University of Missouri, Columbia, MO, USA
| | | | | | - J L Cera
- New Mexico State University, Las Cruces, NM, USA
| | - N-Y Choi
- Dankook University, Yongin-Si, South Korea
| | | | - D K Danielson
- University of Toronto, Scarborough, Toronto, ON, USA
| | | | - J E Edlund
- Rochester Institute of Technology, Rochester, NY, USA
| | - T Fletcher
- West Liberty University, West Liberty, WV, USA
| | - R E Flinn
- Medical College of Georgia, Augusta University, Augusta, GA, USA
| | | | | | - M Horne
- Richmond, American International University, London, UK
| | - J L Howell
- University of California, Merced, CA, USA
| | - J Hua
- University of California, Merced, CA, USA
| | - E E Ijebor
- New Mexico State University, Las Cruces, NM, USA
| | - F Jia
- Seton Hall University, South Orange, NJ, USA
| | | | - K T U Ogba
- University of Nigeria Nsukka, Nsukka, Nigeria
| | | | - A Staples
- Weatherford College, Weatherford, TX, USA
| | - C F Ugwu
- University of Nigeria Nsukka, Nsukka, Nigeria
| | - S C Wang
- New Mexico State University, Las Cruces, NM, USA
| | - A Yockey
- University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Z Zheng
- Lasell College, Auburndale, MA, USA
| | - M S Zlokovich
- Psi Chi International Honor Society in Psychology, Chattanooga, TN, USA
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2
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Tedeschi A, Dupraz S, Curcio M, Laskowski CJ, Schaffran B, Flynn KC, Santos TE, Stern S, Hilton BJ, Larson MJE, Gurniak CB, Witke W, Bradke F. ADF/Cofilin-Mediated Actin Turnover Promotes Axon Regeneration in the Adult CNS. Neuron 2019; 103:1073-1085.e6. [PMID: 31400829 DOI: 10.1016/j.neuron.2019.07.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/06/2019] [Accepted: 07/08/2019] [Indexed: 11/27/2022]
Abstract
Injured axons fail to regenerate in the adult CNS, which contrasts with their vigorous growth during embryonic development. We explored the potential of re-initiating axon extension after injury by reactivating the molecular mechanisms that drive morphogenetic transformation of neurons during development. Genetic loss- and gain-of-function experiments followed by time-lapse microscopy, in vivo imaging, and whole-mount analysis show that axon regeneration is fueled by elevated actin turnover. Actin depolymerizing factor (ADF)/cofilin controls actin turnover to sustain axon regeneration after spinal cord injury through its actin-severing activity. This pinpoints ADF/cofilin as a key regulator of axon growth competence, irrespective of developmental stage. These findings reveal the central role of actin dynamics regulation in this process and elucidate a core mechanism underlying axon growth after CNS trauma. Thereby, neurons maintain the capacity to stimulate developmental programs during adult life, expanding their potential for plasticity. Thus, actin turnover is a key process for future regenerative interventions.
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Affiliation(s)
- Andrea Tedeschi
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Sebastian Dupraz
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Michele Curcio
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Claudia J Laskowski
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Barbara Schaffran
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Kevin C Flynn
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Telma E Santos
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Sina Stern
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Brett J Hilton
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Molly J E Larson
- Center for Brain and Spinal Cord Repair, Department of Neuroscience, Wexner Medical Center, The Ohio State University, 460 W. 12th Ave., Columbus, OH 43210, USA
| | - Christine B Gurniak
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany
| | - Walter Witke
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany
| | - Frank Bradke
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany.
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3
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Raju D, Schonauer S, Hamzeh H, Flynn KC, Bradke F, vom Dorp K, Dörmann P, Yildiz Y, Trötschel C, Poetsch A, Breiden B, Sandhoff K, Körschen HG, Wachten D. Accumulation of glucosylceramide in the absence of the beta-glucosidase GBA2 alters cytoskeletal dynamics. PLoS Genet 2015; 11:e1005063. [PMID: 25803043 PMCID: PMC4372435 DOI: 10.1371/journal.pgen.1005063] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 02/09/2015] [Indexed: 11/18/2022] Open
Abstract
Glycosphingolipids are key elements of cellular membranes, thereby, controlling a variety of cellular functions. Accumulation of the simple glycosphingolipid glucosylceramide results in life-threatening lipid storage-diseases or in male infertility. How glucosylceramide regulates cellular processes is ill defined. Here, we reveal that glucosylceramide accumulation in GBA2 knockout-mice alters cytoskeletal dynamics due to a more ordered lipid organization in the plasma membrane. In dermal fibroblasts, accumulation of glucosylceramide augments actin polymerization and promotes microtubules persistence, resulting in a higher number of filopodia and lamellipodia and longer microtubules. Similar cytoskeletal defects were observed in male germ and Sertoli cells from GBA2 knockout-mice. In particular, the organization of F-actin structures in the ectoplasmic specialization and microtubules in the sperm manchette is affected. Thus, glucosylceramide regulates cytoskeletal dynamics, providing mechanistic insights into how glucosylceramide controls signaling pathways not only during sperm development, but also in other cell types. During mammalian spermatogenesis, sperm with a head and a tail are formed from a round cell. This process is tightly regulated and involves the close interaction of somatic Sertoli cells and germ cells. Accumulation of the glycosphingolipid glucosylceramide in the absence of the beta-glucosidase GBA2 has been proposed to disturb sperm development, leading to morphological defects. However, the underlying mechanism is not known. Here, we demonstrate that accumulation of glucosylceramide in GBA2 knockout-mice controls the dynamics of the actin and microtubule cytoskeleton, which are crucial for sperm development. In particular, cytoskeletal structures at the interface between Sertoli and germ cells are disorganized, leading to malformation of the sperm head and a defect in acrosome formation. In summary, we provide mechanistic insights into how glucosylceramide controls cellular signaling and dysregulation of this essential glycosphingolipid leads to male infertility.
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Affiliation(s)
- Diana Raju
- Minerva Research Group—Molecular Physiology, Center of Advanced European Studies and Research, Bonn, Germany
| | - Sophie Schonauer
- Minerva Research Group—Molecular Physiology, Center of Advanced European Studies and Research, Bonn, Germany
| | - Hussein Hamzeh
- Minerva Research Group—Molecular Physiology, Center of Advanced European Studies and Research, Bonn, Germany
| | - Kevin C. Flynn
- Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE e.V.), Bonn, Germany
| | - Frank Bradke
- Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE e.V.), Bonn, Germany
| | - Katharina vom Dorp
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Bonn, Germany
| | - Peter Dörmann
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Bonn, Germany
| | - Yildiz Yildiz
- Innere Medizin am Landeskrankenhaus Bregenz, Bregenz, Austria
| | | | - Ansgar Poetsch
- Biochemie der Pflanzen, Ruhr-Universität Bochum, Bochum, Germany
| | - Bernadette Breiden
- Life and Medical Sciences Institute (LIMES) c/o Kekulé-Institute of Chemistry and Biochemistry, Bonn, Germany
| | - Konrad Sandhoff
- Life and Medical Sciences Institute (LIMES) c/o Kekulé-Institute of Chemistry and Biochemistry, Bonn, Germany
| | - Heinz G. Körschen
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research, Bonn, Germany
| | - Dagmar Wachten
- Minerva Research Group—Molecular Physiology, Center of Advanced European Studies and Research, Bonn, Germany
- * E-mail:
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4
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Ruschel J, Hellal F, Flynn KC, Dupraz S, Elliott DA, Tedeschi A, Bates M, Sliwinski C, Brook G, Dobrindt K, Peitz M, Brüstle O, Norenberg MD, Blesch A, Weidner N, Bunge MB, Bixby JL, Bradke F. Axonal regeneration. Systemic administration of epothilone B promotes axon regeneration after spinal cord injury. Science 2015; 348:347-52. [PMID: 25765066 DOI: 10.1126/science.aaa2958] [Citation(s) in RCA: 304] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/25/2015] [Indexed: 12/14/2022]
Abstract
After central nervous system (CNS) injury, inhibitory factors in the lesion scar and poor axon growth potential prevent axon regeneration. Microtubule stabilization reduces scarring and promotes axon growth. However, the cellular mechanisms of this dual effect remain unclear. Here, delayed systemic administration of a blood-brain barrier-permeable microtubule-stabilizing drug, epothilone B (epoB), decreased scarring after rodent spinal cord injury (SCI) by abrogating polarization and directed migration of scar-forming fibroblasts. Conversely, epothilone B reactivated neuronal polarization by inducing concerted microtubule polymerization into the axon tip, which propelled axon growth through an inhibitory environment. Together, these drug-elicited effects promoted axon regeneration and improved motor function after SCI. With recent clinical approval, epothilones hold promise for clinical use after CNS injury.
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Affiliation(s)
- Jörg Ruschel
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Farida Hellal
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Kevin C Flynn
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Sebastian Dupraz
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - David A Elliott
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Andrea Tedeschi
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Margaret Bates
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 Northwest 14th Terrace, Miami, FL33136, USA
| | - Christopher Sliwinski
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstr. 200A, 69118 Heidelberg, Germany
| | - Gary Brook
- Institute for Neuropathology, RWTH Aachen University, Steinbergweg 20, 52074, Aachen, Germany. Jülich-Aachen Research Alliance-Translational Brain Medicine
| | - Kristina Dobrindt
- Institute of Reconstructive Neurobiology, Life&Brain Center, University of Bonn and Hertie Foundation, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Michael Peitz
- Institute of Reconstructive Neurobiology, Life&Brain Center, University of Bonn and Hertie Foundation, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, Life&Brain Center, University of Bonn and Hertie Foundation, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Michael D Norenberg
- Departments of Pathology, Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, FL 33101, USA
| | - Armin Blesch
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstr. 200A, 69118 Heidelberg, Germany
| | - Norbert Weidner
- Spinal Cord Injury Center, Heidelberg University Hospital, Schlierbacher Landstr. 200A, 69118 Heidelberg, Germany
| | - Mary Bartlett Bunge
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 Northwest 14th Terrace, Miami, FL33136, USA
| | - John L Bixby
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 Northwest 14th Terrace, Miami, FL33136, USA
| | - Frank Bradke
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
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5
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Abstract
Neurons begin their life as simple spheres, but can ultimately assume an elaborate morphology with numerous, highly arborized dendrites, and long axons. This is achieved via an astounding developmental progression which is dependent upon regulated assembly and dynamics of the cellular cytoskeleton. As neurites emerge out of the soma, neurons break their spherical symmetry and begin to acquire the morphological features that define their structure and function. Neurons regulate their cytoskeleton to achieve changes in cell shape, velocity, and direction as they migrate, extend neurites, and polarize. Of particular importance, the organization and dynamics of actin and microtubules directs the migration and morphogenesis of neurons. This review focuses on the regulation of intrinsic properties of the actin and microtubule cytoskeletons and how specific cytoskeletal structures and dynamics are associated with the earliest phase of neuronal morphogenesis—neuritogenesis.
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6
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Flynn KC, Hellal F, Neukirchen D, Jacob S, Tahirovic S, Dupraz S, Stern S, Garvalov BK, Gurniak C, Shaw AE, Meyn L, Wedlich-Söldner R, Bamburg JR, Small JV, Witke W, Bradke F. ADF/cofilin-mediated actin retrograde flow directs neurite formation in the developing brain. Neuron 2013; 76:1091-107. [PMID: 23259946 DOI: 10.1016/j.neuron.2012.09.038] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2012] [Indexed: 01/17/2023]
Abstract
Neurites are the characteristic structural element of neurons that will initiate brain connectivity and elaborate information. Early in development, neurons are spherical cells but this symmetry is broken through the initial formation of neurites. This fundamental step is thought to rely on actin and microtubule dynamics. However, it is unclear which aspects of the complex actin behavior control neuritogenesis and which molecular mechanisms are involved. Here, we demonstrate that augmented actin retrograde flow and protrusion dynamics facilitate neurite formation. Our data indicate that a single family of actin regulatory proteins, ADF/Cofilin, provides the required control of actin retrograde flow and dynamics to form neurites. In particular, the F-actin severing activity of ADF/Cofilin organizes space for the protrusion and bundling of microtubules, the backbone of neurites. Our data reveal how ADF/Cofilin organizes the cytoskeleton to drive actin retrograde flow and thus break the spherical shape of neurons.
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Affiliation(s)
- Kevin C Flynn
- Max Planck Institute of Neurobiology, Axonal Growth and Regeneration Group, Am Klopferspitz 18, 82152 Martinsried, Germany
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7
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Hellal F, Hurtado A, Ruschel J, Flynn KC, Laskowski CJ, Umlauf M, Kapitein LC, Strikis D, Lemmon V, Bixby J, Hoogenraad CC, Bradke F. Microtubule stabilization reduces scarring and causes axon regeneration after spinal cord injury. Science 2011; 331:928-31. [PMID: 21273450 DOI: 10.1126/science.1201148] [Citation(s) in RCA: 440] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hypertrophic scarring and poor intrinsic axon growth capacity constitute major obstacles for spinal cord repair. These processes are tightly regulated by microtubule dynamics. Here, moderate microtubule stabilization decreased scar formation after spinal cord injury in rodents through various cellular mechanisms, including dampening of transforming growth factor-β signaling. It prevented accumulation of chondroitin sulfate proteoglycans and rendered the lesion site permissive for axon regeneration of growth-competent sensory neurons. Microtubule stabilization also promoted growth of central nervous system axons of the Raphe-spinal tract and led to functional improvement. Thus, microtubule stabilization reduces fibrotic scarring and enhances the capacity of axons to grow.
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Affiliation(s)
- Farida Hellal
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, Martinsried, Germany
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8
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Marsick BM, Flynn KC, Santiago-Medina M, Bamburg JR, Letourneau PC. Activation of ADF/cofilin mediates attractive growth cone turning toward nerve growth factor and netrin-1. Dev Neurobiol 2010; 70:565-88. [PMID: 20506164 DOI: 10.1002/dneu.20800] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proper neural circuitry requires that growth cones, motile tips of extending axons, respond to molecular guidance cues expressed in the developing organism. However, it is unclear how guidance cues modify the cytoskeleton to guide growth cone pathfinding. Here, we show acute treatment with two attractive guidance cues, nerve growth factor (NGF) and netrin-1, for embryonic dorsal root ganglion and temporal retinal neurons, respectively, results in increased growth cone membrane protrusion, actin polymerization, and filamentous actin (F-actin). ADF/cofilin (AC) family proteins facilitate F-actin dynamics, and we found the inactive phosphorylated form of AC is decreased in NGF- or netrin-1-treated growth cones. Directly increasing AC activity mimics addition of NGF or netrin-1 to increase growth cone protrusion and F-actin levels. Extracellular gradients of NGF, netrin-1, and a cell-permeable AC elicit attractive growth cone turning and increased F-actin barbed ends, F-actin accumulation, and active AC in growth cone regions proximal to the gradient source. Reducing AC activity blunts turning responses to NGF and netrin. Our results suggest that gradients of NGF and netrin-1 locally activate AC to promote actin polymerization and subsequent growth cone turning toward the side containing higher AC activity.
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Affiliation(s)
- Bonnie M Marsick
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA
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9
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Davis RC, Maloney MT, Minamide LS, Flynn KC, Stonebraker MA, Bamburg JR. Mapping cofilin-actin rods in stressed hippocampal slices and the role of cdc42 in amyloid-beta-induced rods. J Alzheimers Dis 2010; 18:35-50. [PMID: 19542631 DOI: 10.3233/jad-2009-1122] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dissociated hippocampal neurons exposed to a variety of degenerative stimuli form neuritic cofilin-actin rods. Here we report on stimulus driven regional rod formation in organotypic hippocampal slices. Ultrastructural analysis of rods formed in slices demonstrates mitochondria and vesicles become entrapped within some rods. We developed a template for combining and mapping data from multiple slices, enabling statistical analysis for the identification of vulnerable sub-regions. Amyloid-beta (Abeta) induces rods predominantly in the dentate gyrus region, and Abeta-induced rods are reversible following washout. Rods that persist 24 h following transient (30 min) ATP-depletion are broadly distributed, whereas rods formed in response to excitotoxic glutamate localize within and nearby the pyramidal neurons. Time-lapse imaging of cofilin-GFP-expressing neurons within slices shows neuronal rod formation begins rapidly and peaks by 10 min of anoxia. In approximately 50% of responding neurons, Abeta-induced rod formation acts via cdc42, an upstream regulator of cofilin. These new observations support a role for cofilin-actin rods in stress-induced disruption of cargo transport and synaptic function within hippocampal neurons and suggest both cdc42-dependent and independent pathways modulate cofilin activity downstream from Abeta.
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Affiliation(s)
- Richard C Davis
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA
| | - Michael T Maloney
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Laurie S Minamide
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Kevin C Flynn
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA.,Max Planck Institute of Neurobiology, Martinsreid, Munich, Germany
| | - Matthew A Stonebraker
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - James R Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA
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10
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Tahirovic S, Hellal F, Neukirchen D, Hindges R, Garvalov BK, Flynn KC, Stradal TE, Chrostek-Grashoff A, Brakebusch C, Bradke F. Rac1 regulates neuronal polarization through the WAVE complex. J Neurosci 2010; 30:6930-43. [PMID: 20484635 PMCID: PMC6632643 DOI: 10.1523/jneurosci.5395-09.2010] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 03/30/2010] [Accepted: 04/03/2010] [Indexed: 11/21/2022] Open
Abstract
Neuronal migration and axon growth, key events during neuronal development, require distinct changes in the cytoskeleton. Although many molecular regulators of polarity have been identified and characterized, relatively little is known about their physiological role in this process. To study the physiological function of Rac1 in neuronal development, we have generated a conditional knock-out mouse, in which Rac1 is ablated in the whole brain. Rac1-deficient cerebellar granule neurons, which do not express other Rac isoforms, showed impaired neuronal migration and axon formation both in vivo and in vitro. In addition, Rac1 ablation disrupts lamellipodia formation in growth cones. The analysis of Rac1 effectors revealed the absence of the Wiskott-Aldrich syndrome protein (WASP) family verprolin-homologous protein (WAVE) complex from the plasma membrane of knock-out growth cones. Loss of WAVE function inhibited axon growth, whereas overexpression of a membrane-tethered WAVE mutant partially rescued axon growth in Rac1-knock-out neurons. In addition, pharmacological inhibition of the WAVE complex effector Arp2/3 also reduced axon growth. We propose that Rac1 recruits the WAVE complex to the plasma membrane to enable actin remodeling necessary for axon growth.
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Affiliation(s)
- Sabina Tahirovic
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Farida Hellal
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Dorothee Neukirchen
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Robert Hindges
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Boyan K. Garvalov
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Kevin C. Flynn
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Theresia E. Stradal
- Signalling and Motility Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Anna Chrostek-Grashoff
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908, and
| | - Cord Brakebusch
- Biotech Research and Innovation Centre, Biomedical Institute, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Frank Bradke
- Axonal Growth and Regeneration Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
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11
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Bamburg JR, Bernstein BW, Davis RC, Flynn KC, Goldsbury C, Jensen JR, Maloney MT, Marsden IT, Minamide LS, Pak CW, Shaw AE, Whiteman I, Wiggan O. ADF/Cofilin-actin rods in neurodegenerative diseases. Curr Alzheimer Res 2010; 7:241-50. [PMID: 20088812 PMCID: PMC4458070 DOI: 10.2174/156720510791050902] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Accepted: 11/24/2009] [Indexed: 11/22/2022]
Abstract
Dephosphorylation (activation) of cofilin, an actin binding protein, is stimulated by initiators of neuronal dysfunction and degeneration including oxidative stress, excitotoxic glutamate, ischemia, and soluble forms of beta-amyloid peptide (Abeta). Hyperactive cofilin forms rod-shaped cofilin-saturated actin filament bundles (rods). Other proteins are recruited to rods but are not necessary for rod formation. Neuronal cytoplasmic rods accumulate within neurites where they disrupt synaptic function and are a likely cause of synaptic loss without neuronal loss, as occurs early in dementias. Different rod-inducing stimuli target distinct neuronal populations within the hippocampus. Rods form rapidly, often in tandem arrays, in response to stress. They accumulate phosphorylated tau that immunostains for epitopes present in "striated neuropil threads," characteristic of tau pathology in Alzheimer disease (AD) brain. Thus, rods might aid in further tau modifications or assembly into paired helical filaments, the major component of neurofibrillary tangles (NFTs). Rods can occlude neurites and block vesicle transport. Some rod-inducing treatments cause an increase in secreted Abeta. Thus rods may mediate the loss of synapses, production of excess Abeta, and formation of NFTs, all of the pathological hallmarks of AD. Cofilin-actin rods also form within the nucleus of heat-shocked neurons and are cleared from cells expressing wild type huntingtin protein but not in cells expressing mutant or silenced huntingtin, suggesting a role for nuclear rods in Huntington disease (HD). As an early event in the neurodegenerative cascade, rod formation is an ideal target for therapeutic intervention that might be useful in treatment of many different neurological diseases.
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Affiliation(s)
- J R Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, 80523, USA.
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Flynn KC, Pak CW, Shaw AE, Bradke F, Bamburg JR. Growth cone-like waves transport actin and promote axonogenesis and neurite branching. Dev Neurobiol 2009; 69:761-79. [PMID: 19513994 DOI: 10.1002/dneu.20734] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Axonogenesis involves a shift from uniform delivery of materials to all neurites to preferential delivery to the putative axon, supporting its more rapid extension. Waves, growth cone-like structures that propagate down the length of neurites, were shown previously to correlate with neurite growth in dissociated cultured hippocampal neurons. Waves are similar to growth cones in their structure, composition and dynamics. Here, we report that waves form in all undifferentiated neurites, but occur more frequently in the future axon during initial neuronal polarization. Moreover, wave frequency and their impact on neurite growth are altered in neurons treated with stimuli that enhance axonogenesis. Coincident with wave arrival, growth cones enlarge and undergo a marked increase in dynamics. Through their engorgement of filopodia along the neurite shaft, waves can induce de novo neurite branching. Actin in waves maintains much of its cohesiveness during transport whereas actin in nonwave regions of the neurite rapidly diffuses as measured by live cell imaging of photoactivated GFP-actin and photoconversion of Dendra-actin. Thus, waves represent an alternative axonal transport mechanism for actin. Waves also occur in neurons in organotypic hippocampal slices where they propagate along neurites in the dentate gyrus and the CA regions and induce branching. Taken together, our results indicate that waves are physiologically relevant and contribute to axon growth and branching via the transport of actin and by increasing growth cone dynamics.
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Affiliation(s)
- Kevin C Flynn
- Graduate Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA
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