1
|
Kim CN, Shin D, Wang A, Nowakowski TJ. Spatiotemporal molecular dynamics of the developing human thalamus. Science 2023; 382:eadf9941. [PMID: 37824646 PMCID: PMC10758299 DOI: 10.1126/science.adf9941] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 09/15/2023] [Indexed: 10/14/2023]
Abstract
The thalamus plays a central coordinating role in the brain. Thalamic neurons are organized into spatially distinct nuclei, but the molecular architecture of thalamic development is poorly understood, especially in humans. To begin to delineate the molecular trajectories of cell fate specification and organization in the developing human thalamus, we used single-cell and multiplexed spatial transcriptomics. We show that molecularly defined thalamic neurons differentiate in the second trimester of human development and that these neurons organize into spatially and molecularly distinct nuclei. We identified major subtypes of glutamatergic neuron subtypes that are differentially enriched in anatomically distinct nuclei and six subtypes of γ-aminobutyric acid-mediated (GABAergic) neurons that are shared and distinct across thalamic nuclei.
Collapse
Affiliation(s)
- Chang N Kim
- Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA
- Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA 94143, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, CA 94143, USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 94143, USA
- Weill Institute for Neurosciences, University of California, San Francisco, CA 94158, USA
| | - David Shin
- Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA
- Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA 94143, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, CA 94143, USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 94143, USA
- Weill Institute for Neurosciences, University of California, San Francisco, CA 94158, USA
| | - Albert Wang
- Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA
| | - Tomasz J Nowakowski
- Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA
- Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA 94143, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, CA 94143, USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 94143, USA
- Weill Institute for Neurosciences, University of California, San Francisco, CA 94158, USA
| |
Collapse
|
2
|
Kim CN, Shin D, Wang A, Nowakowski TJ. Spatiotemporal molecular dynamics of the developing human thalamus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.21.554174. [PMID: 37662287 PMCID: PMC10473600 DOI: 10.1101/2023.08.21.554174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
The thalamus plays a central coordinating role in the brain. Thalamic neurons are organized into spatially-distinct nuclei, but the molecular architecture of thalamic development is poorly understood, especially in humans. To begin to delineate the molecular trajectories of cell fate specification and organization in the developing human thalamus, we used single cell and multiplexed spatial transcriptomics. Here we show that molecularly-defined thalamic neurons differentiate in the second trimester of human development, and that these neurons organize into spatially and molecularly distinct nuclei. We identify major subtypes of glutamatergic neuron subtypes that are differentially enriched in anatomically distinct nuclei. In addition, we identify six subtypes of GABAergic neurons that are shared and distinct across thalamic nuclei. One-Sentence Summary Single cell and spatial profiling of the developing thalamus in the first and second trimester yields molecular mechanisms of thalamic nuclei development.
Collapse
|
3
|
Harcha PA, Garcés P, Arredondo C, Fernández G, Sáez JC, van Zundert B. Mast Cell and Astrocyte Hemichannels and Their Role in Alzheimer's Disease, ALS, and Harmful Stress Conditions. Int J Mol Sci 2021; 22:ijms22041924. [PMID: 33672031 PMCID: PMC7919494 DOI: 10.3390/ijms22041924] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/02/2021] [Accepted: 02/11/2021] [Indexed: 02/07/2023] Open
Abstract
Considered relevant during allergy responses, numerous observations have also identified mast cells (MCs) as critical effectors during the progression and modulation of several neuroinflammatory conditions, including Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS). MC granules contain a plethora of constituents, including growth factors, cytokines, chemokines, and mitogen factors. The release of these bioactive substances from MCs occurs through distinct pathways that are initiated by the activation of specific plasma membrane receptors/channels. Here, we focus on hemichannels (HCs) formed by connexins (Cxs) and pannexins (Panxs) proteins, and we described their contribution to MC degranulation in AD, ALS, and harmful stress conditions. Cx/Panx HCs are also expressed by astrocytes and are likely involved in the release of critical toxic amounts of soluble factors—such as glutamate, adenosine triphosphate (ATP), complement component 3 derivate C3a, tumor necrosis factor (TNFα), apoliprotein E (ApoE), and certain miRNAs—known to play a role in the pathogenesis of AD, ALS, and other neurodegenerative disorders. We propose that blocking HCs on MCs and glial cells offers a promising novel strategy for ameliorating the progression of neurodegenerative diseases by reducing the release of cytokines and other pro-inflammatory compounds.
Collapse
Affiliation(s)
- Paloma A. Harcha
- Instituto de Neurociencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Valparaíso 2381850, Chile
- Correspondence: (P.A.H.); (J.C.S.); (B.v.Z.)
| | - Polett Garcés
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago 8370186, Chile; (P.G.); (C.A.); (G.F.)
- CARE Biomedical Research Center, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 8330005, Chile
| | - Cristian Arredondo
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago 8370186, Chile; (P.G.); (C.A.); (G.F.)
- CARE Biomedical Research Center, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 8330005, Chile
| | - Germán Fernández
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago 8370186, Chile; (P.G.); (C.A.); (G.F.)
- CARE Biomedical Research Center, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 8330005, Chile
| | - Juan C. Sáez
- Instituto de Neurociencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Valparaíso 2381850, Chile
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
- Correspondence: (P.A.H.); (J.C.S.); (B.v.Z.)
| | - Brigitte van Zundert
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago 8370186, Chile; (P.G.); (C.A.); (G.F.)
- CARE Biomedical Research Center, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 8330005, Chile
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Correspondence: (P.A.H.); (J.C.S.); (B.v.Z.)
| |
Collapse
|
4
|
Vicario N, Turnaturi R, Spitale FM, Torrisi F, Zappalà A, Gulino R, Pasquinucci L, Chiechio S, Parenti C, Parenti R. Intercellular communication and ion channels in neuropathic pain chronicization. Inflamm Res 2020; 69:841-850. [PMID: 32533221 DOI: 10.1007/s00011-020-01363-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Neuropathic pain is caused by primary lesion or dysfunction of either peripheral or central nervous system. Due to its complex pathogenesis, often related to a number of comorbidities, such as cancer, neurodegenerative and neurovascular diseases, neuropathic pain still represents an unmet clinical need, lacking long-term effective treatment and complex case-by-case approach. AIM AND METHODS We analyzed the recent literature on the role of selective voltage-sensitive sodium, calcium and potassium permeable channels and non-selective gap junctions (GJs) and hemichannels (HCs) in establishing and maintaining chronic neuropathic conditions. We finally focussed our review on the role of extracellular microenvironment modifications induced by resident glial cells and on the recent advances in cell-to-cell and cell-to-extracellular environment communication in chronic neuropathies. CONCLUSION In this review, we provide an update on the current knowledge of neuropathy chronicization processes with a focus on both neuronal and glial ion channels, as well as on channel-mediated intercellular communication.
Collapse
Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rita Turnaturi
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Federica Maria Spitale
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Torrisi
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Lorella Pasquinucci
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Santina Chiechio
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy
- Oasi Research Institute IRCCS, Troina, Italy
| | - Carmela Parenti
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy.
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.
| |
Collapse
|
5
|
Kim B, De La Monte S, Hovanesian V, Patra A, Chen X, Chen RH, Miller MC, Pinar MH, Lim YP, Stopa EG, Stonestreet BS. Ontogeny of inter-alpha inhibitor protein (IAIP) expression in human brain. J Neurosci Res 2019; 98:869-887. [PMID: 31797408 DOI: 10.1002/jnr.24565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/11/2019] [Accepted: 11/11/2019] [Indexed: 12/19/2022]
Abstract
Inter-alpha inhibitor proteins (IAIPs) are naturally occurring immunomodulatory molecules found in most tissues. We have reported ontogenic changes in the expression of IAIPs in brain during development in sheep and abundant expression of IAIPs in fetal and neonatal rodent brain in a variety of cellular types and brain regions. Although a few studies identified bikunin, light chain of IAIPs, in adult human brain, the presence of the complete endogenous IAIP protein complex has not been reported in human brain. In this study, we examined the immunohistochemical expression of endogenous IAIPs in human cerebral cortex from early in development through the neonatal period and in adults using well-preserved postmortem brains. We examined total, nuclear, and cytoplasmic staining of endogenous IAIPs and their expression in neurofilament light polypeptide-positive neurons and glial fibrillary acidic protein (GFAP)-positive astrocytes. IAIPs were ubiquitously detected for the first time in cerebral cortical cells at 24-26, 27-28, 29-36, and 37-40 weeks of gestation and in adults. Quantitative analyses revealed that IAIPs were predominately localized in the nucleus in all age groups, but cytoplasmic IAIP expression was more abundant in adult than in the younger ages. Immunoreactivity of IAIPs was expressed in neurons and astrocytes in all age groups. In addition, IAIP co-localization with GFAP-positive astrocytes was more abundant in adults than in the developing brain. We conclude that IAIPs exhibit ubiquitous expression, and co-localize with neurons and astrocytes in the developing and adult human brain suggesting a potential role for IAIPs in development and endogenous neuroprotection.
Collapse
Affiliation(s)
- Boram Kim
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA
| | - Suzanne De La Monte
- Department of Neurology and Neurosurgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, USA
| | | | - Aparna Patra
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA
| | - Xiaodi Chen
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA
| | - Ray H Chen
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA
| | - Miles C Miller
- Department of Pathology and Neurosurgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, USA
| | - Mehmet Halit Pinar
- Department of Pathology & Laboratory Medicine, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA
| | - Yow-Pin Lim
- Department of Pathology & Laboratory Medicine, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA.,ProThera Biologics, Inc., Providence, RI, USA
| | - Edward G Stopa
- Department of Pathology and Neurosurgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, USA
| | - Barbara S Stonestreet
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island, Providence, RI, USA
| |
Collapse
|
6
|
Almad AA, Doreswamy A, Gross SK, Richard JP, Huo Y, Haughey N, Maragakis NJ. Connexin 43 in astrocytes contributes to motor neuron toxicity in amyotrophic lateral sclerosis. Glia 2016; 64:1154-69. [PMID: 27083773 DOI: 10.1002/glia.22989] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 03/09/2016] [Accepted: 03/30/2016] [Indexed: 11/09/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of motor neurons in the CNS. Astrocytes play a critical role in disease progression of ALS. Astrocytes are interconnected through a family of gap junction proteins known as connexins (Cx). Cx43 is a major astrocyte connexin conducting crucial homeostatic functions in the CNS. Under pathological conditions, connexin expression and functions are altered. Here we report that an abnormal increase in Cx43 expression serves as one of the mechanisms for astrocyte-mediated toxicity in ALS. We observed a progressive increase in Cx43 expression in the SOD1(G93A) mouse model of ALS during the disease course. Notably, this increase in Cx43 was also detected in the motor cortex and spinal cord of ALS patients. Astrocytes isolated from SOD1(G93A) mice as well as human induced pluripotent stem cell (iPSC)-derived astrocytes showed an increase in Cx43 protein, which was found to be an endogenous phenomenon independent of neuronal co-culture. Increased Cx43 expression led to important functional consequences when tested in SOD1(G93A) astrocytes when compared to control astrocytes over-expressing wild-type SOD1 (SOD1(WT) ). We observed SOD1(G93A) astrocytes exhibited enhanced gap junction coupling, increased hemichannel-mediated activity, and elevated intracellular calcium levels. Finally, we tested the impact of increased expression of Cx43 on MN survival and observed that use of both a pan Cx43 blocker and Cx43 hemichannel blocker conferred neuroprotection to MNs cultured with SOD1(G93A) astrocytes. These novel findings show a previously unrecognized role of Cx43 in ALS-related motor neuron loss. GLIA 2016;64:1154-1169.
Collapse
Affiliation(s)
- Akshata A Almad
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| | - Arpitha Doreswamy
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| | - Sarah K Gross
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| | - Jean-Philippe Richard
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| | - Yuqing Huo
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| | - Norman Haughey
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| | - Nicholas J Maragakis
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland
| |
Collapse
|
7
|
Scemes E, Spray DC. Extracellular K⁺ and astrocyte signaling via connexin and pannexin channels. Neurochem Res 2012; 37:2310-6. [PMID: 22481627 DOI: 10.1007/s11064-012-0759-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 03/09/2012] [Accepted: 03/21/2012] [Indexed: 10/28/2022]
Abstract
Astrocytes utilize two major pathways to achieve long distance intercellular communication. One pathway involves direct gap junction mediated signal transmission and the other consists of release of ATP through pannexin channels and excitation of purinergic receptors on nearby cells. Elevated extracellular potassium to levels occurring around hyperactive neurons affects both gap junction and pannexin1 channels. The action on Cx43 gap junctions is to increase intercellular coupling for a period that long outlasts the stimulus. This long term increase in coupling, termed "LINC", is mediated through calcium and calmodulin dependent activation of calmodulin dependent kinase (CaMK). Pannexin1 can be activated by elevations in extracellular potassium through a mechanism that is quite different. In this case, potassium shifts activation potentials to more physiological range, thereby allowing channel opening at resting or slightly depolarized potentials. Enhanced activity of both these channel types by elevations in extracellular potassium of the magnitude occurring during periods of high neuronal activity likely has profound effects on intercellular signaling among astrocytes in the nervous system.
Collapse
Affiliation(s)
- Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | | |
Collapse
|
8
|
Zeinieh MP, Talhouk RS, El-Sabban ME, Mikati MA. Differential expression of hippocampal connexins after acute hypoxia in the developing brain. Brain Dev 2010; 32:810-7. [PMID: 20034754 DOI: 10.1016/j.braindev.2009.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 09/30/2009] [Accepted: 11/05/2009] [Indexed: 01/28/2023]
Abstract
Acute hypoxia at postnatal day (P) 10 is an accepted model of human neonatal hypoxia which results, among other consequences, in increased hippocampal excitability. Hypoxic-ischemic injury, which mimics stroke, has been shown to result in changes in connexins (Cxs), however, changes in Cxs have not been studied in the P10 hypoxia model. The aim of this study was to investigate changes in the hippocampal expression of three different connexins at consecutive developmental stages after acute hypoxia at P10 (10min and 30min after reoxygenation, P11, P14, P17, P29, and P45) as compared to sham manipulated pups. After acute hypoxia at P10, Cx30 protein levels were increased at 30min after reoxygenation, at P11 and at P14, and then returned to control levels. Cx36 protein levels transiently decreased at P11 after acute hypoxia then returned to control levels. Cx43 protein levels did not change at any of the time points. Although changes in mRNA expression were observed during development for Cx30 only, acute hypoxia did not result in changes in mRNA expression of all these Cxs when compared to age matched controls suggesting that acute hypoxia induced posttranslational changes in protein expression.
Collapse
Affiliation(s)
- Michele P Zeinieh
- Department of Biology, American University of Beirut, Beirut, Lebanon
| | | | | | | |
Collapse
|
9
|
In vivo development of outer retinal synapses in the absence of glial contact. J Neurosci 2010; 30:11951-61. [PMID: 20826659 DOI: 10.1523/jneurosci.3391-10.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Astroglia secrete factors that promote synapse formation and maintenance. In culture, glial contact has also been shown to facilitate synaptogenesis. Here, we examined whether glial contact is important for establishing circuits in vivo by simultaneously monitoring differentiation of glial cells and local synaptogenesis over time. Photoreceptor circuits of the vertebrate retina are particularly suitable for this study because of the relatively simple, laminar organization of their connectivity with their target neurons, horizontal cells and bipolar cells. Also, individual photoreceptor terminals are ensheathed within the outer plexiform layer (OPL) by the processes of one type of glia, Müller glia cells (MGs). We conducted in vivo time-lapse multiphoton imaging of the rapidly developing and relatively transparent zebrafish retina to ascertain the time course of MG development relative to OPL synaptogenesis. The emergence of synaptic triads, indicative of functional photoreceptor circuits, and structural association with glial processes were also examined across ages by electron microscopy. We first show that MG processes form territories that tile within the inner and outer synaptic layers. We then demonstrate that cone photoreceptor synapses are assembled before the elaboration of MG processes in the OPL. Using a targeted cell ablation approach, we also determined whether the maintenance of photoreceptor synapses is perturbed when local MGs are absent. We found that removal of MGs had no appreciable effect on the stability of newly formed cone synapses. Thus, in contrast to other CNS circuits, contact from glia is not necessary for the formation or immediate stabilization of outer retinal synapses.
Collapse
|
10
|
Haynes RL, Folkerth RD, Trachtenberg FL, Volpe JJ, Kinney HC. Nitrosative stress and inducible nitric oxide synthase expression in periventricular leukomalacia. Acta Neuropathol 2009; 118:391-9. [PMID: 19415311 DOI: 10.1007/s00401-009-0540-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 04/14/2009] [Accepted: 04/14/2009] [Indexed: 12/13/2022]
Abstract
Periventricular leukomalacia (PVL) is a lesion of the immature cerebral white matter in the perinatal period and associated predominantly with prematurity and cerebral ischemia/reperfusion as well as inflammation due to maternofetal infection. It consists of focal necrosis in the periventricular region and diffuse gliosis with microglial activation and premyelinating oligodendrocyte (pre-OL) injury in the surrounding white matter. We previously showed nitrotyrosine in pre-OLs in PVL, suggesting involvement of nitrosative stress in this disorder. Here we hypothesize that inducible nitric oxide synthase (iNOS) expression is increased in PVL relative to controls. Using immunocytochemistry in human archival tissue, the density of iNOS-expressing cells was determined in the cerebral white matter of 15 PVL cases [29-51 postconceptional (PC) weeks] and 16 control cases (20-144 PC weeks). Using a standardization score of 0-3, the density of iNOS-positive cells was significantly increased in the diffuse component of PVL (score of 1.8 +/- 0.3) cases compared to controls (score of 0.7 +/- 0.3) (P = 0.01). Intense iNOS expression occurred in reactive astrocytes in acute through chronic stages and in activated microglia primarily in the acute stage, suggesting an early role for microglial iNOS in PVL's pathogenesis. This study supports an important role for iNOS-induced nitrosative stress in the reactive/inflammatory component of PVL.
Collapse
Affiliation(s)
- Robin L Haynes
- Departments of Pathology, Children's Hospital Boston, Boston, MA 02115, USA.
| | | | | | | | | |
Collapse
|
11
|
Imbeault S, Gauvin LG, Toeg HD, Pettit A, Sorbara CD, Migahed L, DesRoches R, Menzies AS, Nishii K, Paul DL, Simon AM, Bennett SA. The extracellular matrix controls gap junction protein expression and function in postnatal hippocampal neural progenitor cells. BMC Neurosci 2009; 10:13. [PMID: 19236721 PMCID: PMC2655299 DOI: 10.1186/1471-2202-10-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 02/24/2009] [Indexed: 11/23/2022] Open
Abstract
Background Gap junction protein and extracellular matrix signalling systems act in concert to influence developmental specification of neural stem and progenitor cells. It is not known how these two signalling systems interact. Here, we examined the role of ECM components in regulating connexin expression and function in postnatal hippocampal progenitor cells. Results We found that Cx26, Cx29, Cx30, Cx37, Cx40, Cx43, Cx45, and Cx47 mRNA and protein but only Cx32 and Cx36 mRNA are detected in distinct neural progenitor cell populations cultured in the absence of exogenous ECM. Multipotential Type 1 cells express Cx26, Cx30, and Cx43 protein. Their Type 2a progeny but not Type 2b and 3 neuronally committed progenitor cells additionally express Cx37, Cx40, and Cx45. Cx29 and Cx47 protein is detected in early oligodendrocyte progenitors and mature oligodendrocytes respectively. Engagement with a laminin substrate markedly increases Cx26 protein expression, decreases Cx40, Cx43, Cx45, and Cx47 protein expression, and alters subcellular localization of Cx30. These changes are associated with decreased neurogenesis. Further, laminin elicits the appearance of Cx32 protein in early oligodendrocyte progenitors and Cx36 protein in immature neurons. These changes impact upon functional connexin-mediated hemichannel activity but not gap junctional intercellular communication. Conclusion Together, these findings demonstrate a new role for extracellular matrix-cell interaction, specifically laminin, in the regulation of intrinsic connexin expression and function in postnatal neural progenitor cells.
Collapse
Affiliation(s)
- Sophie Imbeault
- Neural Regeneration Laboratory and Ottawa Institute of Systems Biology, Dept. of Biochemistry, Microbiology, and Immunology, University of Ottawa, ON, Canada.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Orellana JA, Sáez PJ, Shoji KF, Schalper KA, Palacios-Prado N, Velarde V, Giaume C, Bennett MVL, Sáez JC. Modulation of brain hemichannels and gap junction channels by pro-inflammatory agents and their possible role in neurodegeneration. Antioxid Redox Signal 2009; 11:369-99. [PMID: 18816186 PMCID: PMC2713807 DOI: 10.1089/ars.2008.2130] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In normal brain, neurons, astrocytes, and oligodendrocytes, the most abundant and active cells express pannexins and connexins, protein subunits of two families forming membrane channels. Most available evidence indicates that in mammals endogenously expressed pannexins form only hemichannels and connexins form both gap junction channels and hemichannels. Whereas gap junction channels connect the cytoplasm of contacting cells and coordinate electric and metabolic activity, hemichannels communicate the intra- and extracellular compartments and serve as a diffusional pathway for ions and small molecules. A subthreshold stimulation by acute pathological threatening conditions (e.g., global ischemia subthreshold for cell death) enhances neuronal Cx36 and glial Cx43 hemichannel activity, favoring ATP release and generation of preconditioning. If the stimulus is sufficiently deleterious, microglia become overactivated and release bioactive molecules that increase the activity of hemichannels and reduce gap junctional communication in astroglial networks, depriving neurons of astrocytic protective functions, and further reducing neuronal viability. Continuous glial activation triggered by low levels of anomalous proteins expressed in several neurodegenerative diseases induce glial hemichannel and gap junction channel disorders similar to those of acute inflammatory responses triggered by ischemia or infectious diseases. These changes are likely to occur in diverse cell types of the CNS and contribute to neurodegeneration during inflammatory process.
Collapse
Affiliation(s)
- Juan A Orellana
- Departamento de Ciencias Fisiológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Abstract
Gap junctions facilitate direct cytoplasmic communication between neighboring cells, facilitating the transfer of small molecular weight molecules involved in cell signaling and metabolism. Gap junction channels are formed by the joining of two hemichannels from adjacent cells, each composed of six oligomeric protein subunits called connexins. Of paramount importance to CNS homeostasis are astrocyte networks formed by gap junctions, which play a critical role in maintaining the homeostatic regulation of extracellular pH, K+, and glutamate levels. Inflammation is a hallmark of several diseases afflicting the CNS. Within the past several years, the number of publications reporting effects of cytokines and pathogenic stimuli on glial gap junction communication has increased dramatically. The purpose of this review is to discuss recent observations characterizing the consequences of inflammatory stimuli on homocellular gap junction coupling in astrocytes and microglia as well as changes in connexin expression during various CNS inflammatory conditions.
Collapse
Affiliation(s)
- Tammy Kielian
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
| |
Collapse
|