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  1. Article ; Online: Myelination is delayed during postnatal brain development in the mdx mouse model of Duchenne muscular dystrophy.

    Aranmolate, Azeez / Tse, Nathaniel / Colognato, Holly

    BMC neuroscience

    2017  Volume 18, Issue 1, Page(s) 63

    Abstract: Background: In Duchenne muscular dystrophy (DMD), the loss of the dystrophin component of the dystrophin-glycoprotein complex (DGC) compromises plasma membrane integrity in skeletal muscle, resulting in extensive muscle degeneration. In addition, many ... ...

    Abstract Background: In Duchenne muscular dystrophy (DMD), the loss of the dystrophin component of the dystrophin-glycoprotein complex (DGC) compromises plasma membrane integrity in skeletal muscle, resulting in extensive muscle degeneration. In addition, many DMD patients exhibit brain deficits in which the cellular etiology remains poorly understood. We recently found that dystroglycan, a receptor component of the DGC that binds intracellularly to dystrophin, regulates the development of oligodendrocytes, the myelinating glial cells of the brain.
    Results: We investigated whether dystrophin contributes to oligodendroglial function and brain myelination. We found that oligodendrocytes express up to three dystrophin isoforms, in conjunction with classic DGC components, which are developmentally regulated during differentiation and in response to extracellular matrix engagement. We found that mdx mice, a model of DMD lacking expression of the largest dystrophin isoform, have delayed myelination and inappropriate oligodendrocyte progenitor proliferation in the cerebral cortex. When we prevented the expression of all oligodendroglial dystrophin isoforms in cultured oligodendrocytes using RNA interference, we found that later stages of oligodendrocyte maturation were significantly delayed, similar to mdx phenotypes in the developing brain.
    Conclusions: We find that dystrophin is expressed in oligodendrocytes and influences developmental myelination, which provides new insight into potential cellular contributors to brain dysfunction associated with DMD.
    MeSH term(s) Animals ; Brain/growth & development ; Brain/metabolism ; Brain/pathology ; Cells, Cultured ; Disease Models, Animal ; Female ; Gene Expression Regulation, Developmental ; Male ; Mice, Inbred C57BL ; Mice, Inbred mdx ; Muscular Dystrophy, Duchenne/metabolism ; Muscular Dystrophy, Duchenne/pathology ; Neural Stem Cells/metabolism ; Neural Stem Cells/pathology ; Oligodendroglia/metabolism ; Oligodendroglia/pathology ; Protein Isoforms ; RNA Interference ; RNA, Messenger/metabolism ; Rats, Sprague-Dawley
    Chemical Substances Protein Isoforms ; RNA, Messenger
    Language English
    Publishing date 2017-08-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1471-2202
    ISSN (online) 1471-2202
    DOI 10.1186/s12868-017-0381-0
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Laminin promotes metalloproteinase-mediated dystroglycan processing to regulate oligodendrocyte progenitor cell proliferation.

    Leiton, Cindy V / Aranmolate, Azeez / Eyermann, Christopher / Menezes, Michael J / Escobar-Hoyos, Luisa F / Husain, Solomon / Winder, Steve J / Colognato, Holly

    Journal of neurochemistry

    2015  Volume 135, Issue 3, Page(s) 522–538

    Abstract: The cell surface receptor dystroglycan mediates interactions between oligodendroglia and laminin-211, an extracellular matrix protein that regulates timely oligodendroglial development. However, dystroglycan's precise role in oligodendroglial development ...

    Abstract The cell surface receptor dystroglycan mediates interactions between oligodendroglia and laminin-211, an extracellular matrix protein that regulates timely oligodendroglial development. However, dystroglycan's precise role in oligodendroglial development and the potential mechanisms to regulate laminin-dystroglycan interactions remain unknown. Here we report that oligodendroglial dystroglycan is cleaved by metalloproteinases, thereby uncoupling oligodendroglia from laminin binding. Dystroglycan cleavage is selectively stimulated by oligodendrocyte progenitor cell attachment to laminin-211, but not laminin-111 or poly-D-lysine. In addition, dystroglycan cleavage occurs most prominently in oligodendrocyte progenitor cells, with limited dystroglycan cleavage observed in differentiating oligodendrocytes. When dystroglycan cleavage is blocked by metalloproteinase inhibitors, oligodendrocyte progenitor cell proliferation is substantially decreased. Conversely, expression of the intracellular portion of cleaved dystroglycan results in increased oligodendrocyte progenitor cell proliferation, suggesting that endogenous dystroglycan cleavage may promote oligodendrocyte progenitor cell cycle progression. Intriguingly, while matrix metalloproteinase-2 and/or -9 have been reported to be responsible for dystroglycan cleavage, we find that these two metalloproteinases are neither necessary nor sufficient for cleavage of oligodendroglial dystroglycan. In summary, laminin-211 stimulates metalloproteinase-mediated dystroglycan cleavage in oligodendrocyte progenitor cells (but not in differentiated oligodendrocytes), which in turn promotes oligodendrocyte progenitor cell proliferation. This novel regulation of oligodendroglial laminin-dystroglycan interactions may have important consequences for oligodendroglial differentiation, both during development and during disease when metalloproteinase levels become elevated.
    MeSH term(s) Animals ; Animals, Newborn ; Cell Proliferation/drug effects ; Cell Proliferation/physiology ; Cells, Cultured ; Dystroglycans/metabolism ; Female ; Laminin/pharmacology ; Metalloproteases/physiology ; Mice ; Oligodendroglia/drug effects ; Oligodendroglia/physiology ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Stem Cells/drug effects ; Stem Cells/physiology
    Chemical Substances Laminin ; Dystroglycans (146888-27-9) ; Metalloproteases (EC 3.4.-)
    Language English
    Publishing date 2015-11
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 80158-6
    ISSN 1471-4159 ; 0022-3042 ; 1474-1644
    ISSN (online) 1471-4159
    ISSN 0022-3042 ; 1474-1644
    DOI 10.1111/jnc.13241
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: The extracellular matrix protein laminin α2 regulates the maturation and function of the blood-brain barrier.

    Menezes, Michael J / McClenahan, Freyja K / Leiton, Cindy V / Aranmolate, Azeez / Shan, Xiwei / Colognato, Holly

    The Journal of neuroscience : the official journal of the Society for Neuroscience

    2014  Volume 34, Issue 46, Page(s) 15260–15280

    Abstract: Laminins are major constituents of the gliovascular basal lamina of the blood-brain barrier (BBB); however, the role of laminins in BBB development remains unclear. Here we report that Lama2(-/-) mice, lacking expression of the laminin α2 subunit of the ... ...

    Abstract Laminins are major constituents of the gliovascular basal lamina of the blood-brain barrier (BBB); however, the role of laminins in BBB development remains unclear. Here we report that Lama2(-/-) mice, lacking expression of the laminin α2 subunit of the laminin-211 heterotrimer expressed by astrocytes and pericytes, have a defective BBB in which systemically circulated tracer leaks into the brain parenchyma. The Lama2(-/-) vascular endothelium had significant abnormalities, including altered integrity and composition of the endothelial basal lamina, inappropriate expression of embryonic vascular endothelial protein MECA32, substantially reduced pericyte coverage, and tight junction abnormalities. Additionally, astrocytic endfeet were hypertrophic and lacked appropriately polarized aquaporin4 channels. Laminin-211 appears to mediate these effects at least in part by dystroglycan receptor interactions, as preventing dystroglycan expression in neural cells led to a similar set of BBB abnormalities and gliovascular disturbances, which additionally included perturbed vascular endothelial glucose transporter-1 localization. These findings provide insight into the cell and molecular changes that occur in congenital muscular dystrophies caused by Lama2 mutations or inappropriate dystroglycan post-translational modifications, which have accompanying brain abnormalities, including seizures. Our results indicate a novel role for laminin-dystroglycan interactions in the cooperative integration of astrocytes, endothelial cells, and pericytes in regulating the BBB.
    MeSH term(s) Animals ; Antigens, Surface/metabolism ; Aquaporin 4/metabolism ; Astrocytes/pathology ; Blood-Brain Barrier/growth & development ; Blood-Brain Barrier/pathology ; Blood-Brain Barrier/physiology ; Dystroglycans/metabolism ; Dystroglycans/physiology ; Endothelium, Vascular/cytology ; Endothelium, Vascular/metabolism ; Glucose Transporter Type 1/metabolism ; Laminin/genetics ; Laminin/physiology ; Mice ; Mice, Knockout ; Mutation ; Neurons/metabolism ; Tight Junctions/pathology
    Chemical Substances Antigens, Surface ; Aquaporin 4 ; Glucose Transporter Type 1 ; Laminin ; MECA-32 antigen, mouse ; laminin alpha 2 ; Dystroglycans (146888-27-9)
    Language English
    Publishing date 2014-05-23
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 604637-x
    ISSN 1529-2401 ; 0270-6474
    ISSN (online) 1529-2401
    ISSN 0270-6474
    DOI 10.1523/JNEUROSCI.3678-13.2014
    Database MEDical Literature Analysis and Retrieval System OnLINE

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