1
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Hernández-Ibarra JA, Laredo-Cisneros MS, Mondragón-González R, Santamaría-Guayasamín N, Cisneros B. Localization of α-Dystrobrevin in Cajal Bodies and Nucleoli: A New Role for α-Dystrobrevin in the Structure/Stability of the Nucleolus. J Cell Biochem 2016; 116:2755-65. [PMID: 25959029 DOI: 10.1002/jcb.25218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/05/2015] [Indexed: 11/11/2022]
Abstract
α-Dystrobrevin (α-DB) is a cytoplasmic component of the dystrophin-associated complex involved in cell signaling; however, its recently revealed nuclear localization implies a role for this protein in the nucleus. Consistent with this, we demonstrated, in a previous work that α-DB1 isoform associates with the nuclear lamin to maintain nuclei morphology. In this study, we show the distribution of the α-DB2 isoform in different subnuclear compartments of N1E115 neuronal cells, including nucleoli and Cajal bodies, where it colocalizes with B23/nucleophosmin and Nopp140 and with coilin, respectively. Recovery in a pure nucleoli fraction undoubtedly confirms the presence of α-DB2 in the nucleolus. α-DB2 redistributes in a similar fashion to that of fibrillarin and Nopp140 upon actinomycin-mediated disruption of nucleoli and to that of coilin after disorganization of Cajal bodies through ultraviolet-irradiation, with relocalization of the proteins to the corresponding reassembled structures after cessation of the insults, which implies α-DB2 in the plasticity of these nuclear bodies. That localization of α-DB2 in the nucleolus is physiologically relevant is demonstrated by the fact that downregulation of α-DB2 resulted in both altered nucleoli structure and decreased levels of B23/nucleophosmin, fibrillarin, and Nopp140. Since α-DB2 interacts with B23/nucleophosmin and overexpression of the latter protein favors nucleolar accumulation of α-DB2, it appears that targeting of α-DB2 to the nucleolus is dependent on B23/nucleophosmin. In conclusion, we show for the first time localization of α-DB2 in nucleoli and Cajal bodies and provide evidence that α-DB2 is involved in the structure of nucleoli and might modulate nucleolar functions.
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Affiliation(s)
- Jose Anselmo Hernández-Ibarra
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
| | - Marco Samuel Laredo-Cisneros
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
| | - Ricardo Mondragón-González
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
| | - Natalie Santamaría-Guayasamín
- Departamento de Ciencias de la Vida, Carrera de Ingeniería en Biotecnología, Universidad de las Fuerzas Armadas-ESPE, Sangolquí, Ecuador
| | - Bulmaro Cisneros
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
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2
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Strakova J, Dean JD, Sharpe KM, Meyers TA, Odom GL, Townsend D. Dystrobrevin increases dystrophin's binding to the dystrophin-glycoprotein complex and provides protection during cardiac stress. J Mol Cell Cardiol 2014; 76:106-15. [PMID: 25158611 DOI: 10.1016/j.yjmcc.2014.08.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 08/14/2014] [Accepted: 08/16/2014] [Indexed: 01/05/2023]
Abstract
Duchenne muscular dystrophy is a fatal progressive disease of both cardiac and skeletal muscle resulting from the mutations in the DMD gene and loss of the protein dystrophin. Alpha-dystrobrevin (α-DB) tightly associates with dystrophin but the significance of this interaction within cardiac myocytes is poorly understood. In the current study, the functional role of α-DB in cardiomyocytes and its implications for dystrophin function are examined. Cardiac stress testing demonstrated significant heart disease in α-DB null (adbn(-/-)) mice, which displayed mortality and lesion sizes that were equivalent to those seen in dystrophin-deficient mdx mice. Despite normal expression and subcellular localization of dystrophin in the adbn(-/-) heart, there is a significant decrease in the strength of dystrophin's interaction with the membrane-bound dystrophin-associated glycoprotein complex (DGC). A similar weakening of the dystrophin-membrane interface was observed in mice lacking the sarcoglycan complex. Cardiomyocytes from adbn(-/-) mice were smaller and responded less to adrenergic receptor induced hypertrophy. The basal decrease in size could not be attributed to aberrant Akt activation. In addition, the organization of the microtubule network was significantly altered in adbn(-/-) cardiac myocytes, while the total expression of tubulin was unchanged in adbn(-/-) hearts. These studies demonstrate that α-DB is a multifunctional protein that increases dystrophin's binding to the dystrophin-glycoprotein complex, and is critical for the full functionality of dystrophin.
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Affiliation(s)
- Jana Strakova
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Jon D Dean
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Katharine M Sharpe
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Tatyana A Meyers
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Guy L Odom
- Department of Neurology, University of Washington, Seattle, WA, USA
| | - DeWayne Townsend
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA.
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3
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Eberhard N, Mayer C, Santic R, Navio RP, Wagner A, Bauer HC, Sperk G, Boehm U, Kofler B. Distribution of alarin immunoreactivity in the mouse brain. J Mol Neurosci 2011; 46:18-32. [PMID: 21647713 PMCID: PMC3260429 DOI: 10.1007/s12031-011-9546-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 05/05/2011] [Indexed: 02/04/2023]
Abstract
Alarin is a 25 amino acid peptide that belongs to the galanin peptide family. It is derived from the galanin-like peptide gene by a splice variant, which excludes exon 3. Alarin was first identified in gangliocytes of neuroblastic tumors and later shown to have a vasoactive function in the skin. Recently, alarin was demonstrated to stimulate food intake as well as the hypothalamic–pituitary–gonadal axis in rodents, suggesting that it might be a neuromodulatory peptide in the brain. However, the individual neurons in the central nervous system that express alarin have not been identified. Here, we determined the distribution of alarin-like immunoreactivity (alarin-LI) in the adult murine brain. The specificity of the antibody against alarin was demonstrated by the absence of labeling after pre-absorption of the antiserum with synthetic alarin peptide and in transgenic mouse brains lacking neurons expressing the GALP gene. Alarin-LI was observed in different areas of the murine brain. A high intensity of alarin-LI was detected in the accessory olfactory bulb, the medial preoptic area, the amygdala, different nuclei of the hypothalamus such as the arcuate nucleus and the ventromedial hypothalamic nucleus, the trigeminal complex, the locus coeruleus, the ventral chochlear nucleus, the facial nucleus, and the epithelial layer of the plexus choroideus. The distinct expression pattern of alarin in the adult mouse brain suggests potential functions in reproduction and metabolism.
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Affiliation(s)
- Nicole Eberhard
- Department of Pediatrics, Laura Bassi Centre of Expertise THERAPEP, Research Program for Receptor Biochemistry and Tumormetabolism, Paracelsus Medical University, Salzburg, 5020 Austria
| | - Christian Mayer
- Institute for Neural Signal Transduction, Center for Molecular Neurobiology, Hamburg, 20253 Hamburg Germany
| | - Radmila Santic
- Department of Pediatrics, Laura Bassi Centre of Expertise THERAPEP, Research Program for Receptor Biochemistry and Tumormetabolism, Paracelsus Medical University, Salzburg, 5020 Austria
| | - Ruben Peco Navio
- Institute for Neural Signal Transduction, Center for Molecular Neurobiology, Hamburg, 20253 Hamburg Germany
| | - Andrea Wagner
- Department of Organismic Biology, University of Salzburg, Salzburg, 5020 Austria
- Department of Applied Cell Biology, Paracelsus Medical University, Salzburg, 5020 Austria
| | - Hans Christian Bauer
- Department of Organismic Biology, University of Salzburg, Salzburg, 5020 Austria
- Department of Applied Cell Biology, Paracelsus Medical University, Salzburg, 5020 Austria
| | - Guenther Sperk
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, 6020 Austria
| | - Ulrich Boehm
- Institute for Neural Signal Transduction, Center for Molecular Neurobiology, Hamburg, 20253 Hamburg Germany
| | - Barbara Kofler
- Department of Pediatrics, Laura Bassi Centre of Expertise THERAPEP, Research Program for Receptor Biochemistry and Tumormetabolism, Paracelsus Medical University, Salzburg, 5020 Austria
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4
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Nakamori M, Takahashi MP. The role of α-dystrobrevin in striated muscle. Int J Mol Sci 2011; 12:1660-71. [PMID: 21673914 PMCID: PMC3111625 DOI: 10.3390/ijms12031660] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/29/2011] [Accepted: 02/23/2011] [Indexed: 12/29/2022] Open
Abstract
Muscular dystrophies are a group of diseases that primarily affect striated muscle and are characterized by the progressive loss of muscle strength and integrity. Major forms of muscular dystrophies are caused by the abnormalities of the dystrophin glycoprotein complex (DGC) that plays crucial roles as a structural unit and scaffolds for signaling molecules at the sarcolemma. α-Dystrobrevin is a component of the DGC and directly associates with dystrophin. α-Dystrobrevin also binds to intermediate filaments as well as syntrophin, a modular adaptor protein thought to be involved in signaling. Although no muscular dystrophy has been associated within mutations of the α-dystrobrevin gene, emerging findings suggest potential significance of α-dystrobrevin in striated muscle. This review addresses the functional role of α-dystrobrevin in muscle as well as its possible implication for muscular dystrophy.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2, D-4, Yamadaoka, Suita, Osaka 565-0871, Japan; E-Mail:
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 645 URMC, Rochester, NY 14642, USA
| | - Masanori P. Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2, D-4, Yamadaoka, Suita, Osaka 565-0871, Japan; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-6-6879-3571; Fax: +81-6-6879-3579
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5
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Abstract
Dystrophin and the alpha-dystrobrevins bind directly to the adapter protein syntrophin to form membrane-associated scaffolds. At the blood-brain barrier, alpha-syntrophin colocalizes with dystrophin and the alpha-dystrobrevins in perivascular glial endfeet and is required for localization of the water channel aquaporin-4. Earlier we have shown that localization of the scaffolding proteins gamma2-syntrophin, alpha-dystrobrevin-2, and dystrophin to glial endfeet is also dependent on the presence of alpha-syntrophin. In this study, we show that the expression levels of alpha-syntrophin, gamma2-syntrophin, and dystrophin at the blood-brain barrier are reduced in alpha-dystrobrevin-null mice. This is the first demonstration in which assembly of an astroglial protein scaffold containing syntrophin and dystrophin in perivascular astrocytes is dependent on the presence of alpha-dystrobrevin.
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6
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Pawlikowski BT, Maimone MM. alpha-Dystrobrevin isoforms differ in their colocalization with and stabilization of agrin-induced acetylcholine receptor clusters. Neuroscience 2008; 154:582-94. [PMID: 18468804 DOI: 10.1016/j.neuroscience.2008.01.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 12/21/2007] [Accepted: 01/12/2008] [Indexed: 11/19/2022]
Abstract
In skeletal muscle, alpha-dystrobrevin (alphaDB) is expressed throughout the sarcolemma with high concentrations at the neuromuscular junction. Mice lacking alphaDB display a mild muscular dystrophy and perturbations at the neuromuscular junction that include disruptions to acetylcholine receptor (AChR) cluster stability and patterning. In adult skeletal muscle, three alternatively spliced isoforms (alphaDB1, alphaDB2, alphaDB3) are expressed, while two other splice variants (alphaDB1(-) and alphaDB2(-)) are expressed only during early development. alphaDB is clearly important in AChR stabilization; however, the degree to which individual alphaDB isoforms and their specific functional domains contribute to AChR cluster stability is not fully understood. To investigate this, we established a primary muscle cell culture system from alphaDB knockout mice and stably expressed individual alphaDB isoforms using retroviral infection. A comparison between wild-type and alphaDB knockout muscle cells showed that in the absence of alphaDB, fewer AChR clusters formed in response to agrin treatment, and these AChR clusters were very unstable. Retroviral expression studies revealed that the largest isoforms (alphaDB1, alphaDB1(-), alphaDB2, alphaDB2(-)) colocalized with agrin-induced AChR clusters and rescued the AChR cluster formation defects back to wild-type levels, while only the first three isoforms fully rescued AChR cluster stability back to wild-type levels. alphaDB2(-) conferred an intermediate level of stability to the AChR clusters. In contrast, alphaDB3 showed no specific colocalization with AChR clusters and little effect on AChR cluster formation or stabilization. Twice as much syntrophin was found associated with alphaDB2 compared with alphaDB2(-) in myotubes suggesting that increased recruitment of syntrophin by alphaDB may enhance the stability of AChR clusters. Taken together, these data demonstrate that different alphaDB isoforms have different functional capabilities in the formation and maintenance of AChR clusters in muscle cells, and that these differences are likely due to the presence of different functional domains in each isoform.
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MESH Headings
- Agrin/pharmacology
- Animals
- Cells, Cultured
- DNA, Complementary/biosynthesis
- DNA, Complementary/genetics
- Dystrophin-Associated Proteins/genetics
- Dystrophin-Associated Proteins/metabolism
- Genetic Vectors
- Isomerism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Confocal
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- Myoblasts/drug effects
- Myoblasts/enzymology
- Plasmids/genetics
- Receptors, Cholinergic/drug effects
- Receptors, Cholinergic/metabolism
- Retroviridae/genetics
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Affiliation(s)
- B T Pawlikowski
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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7
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Santic R, Schmidhuber SM, Lang R, Rauch I, Voglas E, Eberhard N, Bauer JW, Brain SD, Kofler B. Alarin is a vasoactive peptide. Proc Natl Acad Sci U S A 2007; 104:10217-22. [PMID: 17535903 PMCID: PMC1891251 DOI: 10.1073/pnas.0608585104] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Galanin-like peptide (GALP) is a hypothalamic neuropeptide belonging to the galanin family of peptides. The GALP gene is characterized by extensive differential splicing in a variety of murine tissues. One splice variant excludes exon 3 and results in a frame shift leading to a novel peptide sequence and a stop codon after 49 aa. In this peptide, which we termed alarin, the signal sequence of the GALP precursor peptide and the first 5 aa of the mature GALP are followed by 20 aa without homology to any other murine protein. Alarin mRNA was detected in murine brain, thymus, and skin. In accordance with its vascular localization, the peptide exhibited potent and dose-dependent vasoconstrictor and anti-edema activity in the cutaneous microvasculature, as was also observed with other members of the galanin peptide family. However, in contrast to galanin peptides in general, the physiological effects of alarin do not appear to be mediated via the known galanin receptors. Alarin adds another facet to the surprisingly high-functional redundancy of the galanin family of peptides.
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Affiliation(s)
| | | | - Roland Lang
- Dermatology, University Hospital Salzburg, Paracelsus Medical University, Muellner-Hauptstrasse 48, 5020 Salzburg, Austria; and
| | | | | | | | - Johann W. Bauer
- Dermatology, University Hospital Salzburg, Paracelsus Medical University, Muellner-Hauptstrasse 48, 5020 Salzburg, Austria; and
| | - Susan D. Brain
- Cardiovascular Division, King's College London, Franklin Wilkins Building, Waterloo Campus, London SE1 9NH, United Kingdom
| | - Barbara Kofler
- Departments of *Pediatrics and
- To whom correspondence should be addressed. E-mail:
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8
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Compton AG, Cooper ST, Hill PM, Yang N, Froehner SC, North KN. The syntrophin-dystrobrevin subcomplex in human neuromuscular disorders. J Neuropathol Exp Neurol 2005; 64:350-61. [PMID: 15835271 DOI: 10.1093/jnen/64.4.350] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The syntrophins and alpha-dystrobrevin form a subcomplex with dystrophin at the skeletal muscle membrane, and are also highly concentrated at the neuromuscular synapse. Here we demonstrate that the different syntrophins and alpha-dystrobrevin isoforms have distinct expression patterns during human skeletal muscle development, and are differentially affected by loss of dystrophin anchorage and denervation in human neuromuscular disease. During normal fetal development, and in Duchenne muscular dystrophy and denervation disorders, alpha1-syntrophin and alpha-dystrobrevin are absent or markedly reduced at the sarcolemmal membrane. beta1-Syntrophin is the predominant syntrophin isoform expressed at the muscle membrane during development, and it undergoes upregulation in response to loss of alpha1-syntrophin in Duchenne muscular dystrophy and in denervation. Upregulation of beta1-syntrophin in neuromuscular disorders is associated with re-expression of the fetal nicotinic acetylcholine receptor gamma-subunit, cardiac actin, and neonatal myosin, suggesting reversion of muscle fibers to an immature phenotype. We show that denervation specifically affects expression of the syntrophin-dystrobrevin subcomplex and does not affect levels or localization of other members of the dystrophin-associated protein complex. Our results confirm that dystrophin is required for anchorage of the syntrophin-dystrobrevin subcomplex and suggest that expression of the syntrophin-dystrobrevin complex may be independently regulated through neuromuscular transmission.
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Affiliation(s)
- Alison G Compton
- Institute for Neuromuscular Research, Children's Hospital at Westmead, NSW, Australia
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9
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Association of ?-Dystrobrevin with Reorganizing Tight Junctions. J Membr Biol 2005; 203:21-30. [DOI: 10.1007/s00232-004-0728-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Accepted: 12/06/2004] [Indexed: 10/25/2022]
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10
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Albrecht DE, Froehner SC. DAMAGE, a novel alpha-dystrobrevin-associated MAGE protein in dystrophin complexes. J Biol Chem 2003; 279:7014-23. [PMID: 14623885 DOI: 10.1074/jbc.m312205200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mice rendered null for alpha-dystrobrevin, a component of the dystrophin complex, have muscular dystrophy, despite the fact that the sarcolemma remains relatively intact (Grady, R. M., Grange, R. W., Lau, K. S., Maimone, M. M., Nichol, M. C., Stull, J. T., and Sanes, J. R. (1999) Nat. Cell Biol. 1, 215-220) Thus, alpha-dystrobrevin may serve a signaling function that is important for the maintenance of muscle integrity. We have identified a new dystrobrevin-associated protein, DAMAGE, that may play a signaling role in brain, muscle, and peripheral nerve. In humans, DAMAGE is encoded by an intronless gene located at chromosome Xq13.1, a locus that contains genes involved in mental retardation. DAMAGE associates directly with alpha-dystrobrevin, as shown by yeast two-hybrid, and co-immunoprecipitates with the dystrobrevin-syntrophin complex from brain. This co-immunoprecipitation is dependent on the presence of alpha-dystrobrevin but not beta-dystrobrevin. The DAMAGE protein contains a potential nuclear localization signal, 30 12-amino acid repeats, and two MAGE homology domains. The domain structure of DAMAGE is similar to that of NRAGE, a MAGE protein that mediates p75 neurotrophin receptor signaling and neuronal apoptosis (Salehi, A. H., Roux, P. P., Kubu, C. J., Zeindler, C., Bhakar, A., Tannis, L. L., Verdi, J. M., and Barker, P. A. (2000) Neuron 27, 279-288). DAMAGE is highly expressed in brain and is present in the cell bodies and dendrites of hippocampal and Purkinje neurons. In skeletal muscle, DAMAGE is at the postsynaptic membrane and is associated with a subset of myonuclei. DAMAGE is also expressed in peripheral nerve, where it localizes along with other members of the dystrophin complex to the perineurium and myelin. These results expand the role of dystrobrevin and the dystrophin complex in membrane signaling and disease.
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MESH Headings
- Amino Acid Sequence
- Animals
- Apoptosis
- Blotting, Northern
- Blotting, Western
- Brain/metabolism
- Carrier Proteins/chemistry
- Carrier Proteins/genetics
- Carrier Proteins/physiology
- Cloning, Molecular
- Cytoskeletal Proteins/chemistry
- Cytoskeletal Proteins/genetics
- DNA/chemistry
- DNA, Complementary/metabolism
- Dystrophin/chemistry
- Dystrophin-Associated Proteins
- Humans
- Immunohistochemistry
- Introns
- Macaca
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Mice
- Microscopy, Confocal
- Molecular Sequence Data
- Muscle, Skeletal/metabolism
- Muscles/metabolism
- Myelin Sheath/chemistry
- Nerve Tissue Proteins/chemistry
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/physiology
- Neurons/metabolism
- Nuclear Localization Signals
- Peripheral Nervous System/metabolism
- Precipitin Tests
- Protein Binding
- Protein Structure, Tertiary
- Receptor, Nerve Growth Factor
- Receptors, Nerve Growth Factor/metabolism
- Sequence Homology, Amino Acid
- Signal Transduction
- Tissue Distribution
- Transfection
- Two-Hybrid System Techniques
- X Chromosome
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Affiliation(s)
- Douglas E Albrecht
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195-7290, USA
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11
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Jones KJ, Compton AG, Yang N, Mills MA, Peters MF, Mowat D, Kunkel LM, Froehner SC, North KN. Deficiency of the syntrophins and alpha-dystrobrevin in patients with inherited myopathy. Neuromuscul Disord 2003; 13:456-67. [PMID: 12899872 DOI: 10.1016/s0960-8966(03)00066-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The syntrophins and dystrobrevins are members of the dystrophin-associated protein complex, and are thought to function as modular adaptors for signalling proteins recruited to the sarcolemmal membrane. We have characterised the expression of the syntrophins (alpha-, beta1-, and beta2-) and alpha-dystrobrevin by immunohistochemistry in normal human muscle and in biopsies from 162 patients with myopathies of unknown aetiology (with normal staining for dystrophin and other dystrophin-associated proteins). Unlike mice, beta2-syntrophin is expressed at the sarcolemma in post-natal human skeletal muscle. Deficiency of alpha-dystrobrevin +/- beta2-syntrophin was present in 16/162 (10%) patients, compared to age-matched controls. All patients presented with congenital-onset hypotonia and weakness, although there was variability in clinical severity. Two major clinical patterns emerged: patients with deficiency of beta2-syntrophin and alpha-dystrobrevin presented with severe congenital weakness and died in the first year of life, and two patients with deficiency of alpha-dystrobrevin had congenital muscular dystrophy with complete external ophthalmoplegia. We have sequenced the coding regions of alpha-dystrobrevin and beta2-syntrophin in these patients, and identified a new isoform of dystrobrevin, but have not identified any mutations. This suggests that disease causing mutations occur outside the coding region of these genes, in gene(s) encoding other components of the syntrophin-dystrobrevin subcomplex, or in gene(s) responsible for their post-translational modification and normal localisation.
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Affiliation(s)
- K J Jones
- Institute for Neuromuscular Research, The Children's Hospital at Westmead, Locked Bag 4001, NSW 2145, Westmead, Australia
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12
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Springer J, McGregor GP, Fink L, Fischer A. Alternative splicing in single cells dissected from complex tissues: separate expression of prepro-tachykinin A mRNA splice variants in sensory neurones. J Neurochem 2003; 85:882-8. [PMID: 12716420 DOI: 10.1046/j.1471-4159.2003.01720.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Tachykinins play an important role in peripheral inflammatory diseases and disorders of the CNS. Most members of the tachykinin family are generated by alternative post-transcriptional splicing of the prepro-tachykinin (PPT) A gene. Here, we examined the simultaneous expression of PPT-A splice variants in individual neurones of the nodose ganglion. In extracts of ganglia, the expression of the four PPT-A mRNA splice variants and their four encoded peptides was shown by RT-PCR and combined HPLC and radioimmunoassay respectively. In order to examine prepro-tachykinin A expression in individual cells, single neurones were isolated from the ganglia using laser-assisted microdissection and processed for RT-PCR. Some 31.9% of the neurones investigated expressed a specific PPT-A transcript. Each individual neurone was found to express only a single splice variant. This is the first study to analyse the differential expression of PPT-A splice variants at the single-cell level. In view of the large number of alternatively spliced genes in the human genome and the resulting profound physiological effects, including several diseases, the technique described here is useful for isolating cells without possible confounding effects of dissociated neuronal cultures. For PPT-A, the results indicate that alternative post-transcriptional splicing determines the tachykinergic phenotype and may therefore have important functional implications.
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Affiliation(s)
- Jochen Springer
- Department of Anatomy and Cell Biology, Justus-Liebig-University, Giessen, Germany.
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13
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Grady RM, Akaaboune M, Cohen AL, Maimone MM, Lichtman JW, Sanes JR. Tyrosine-phosphorylated and nonphosphorylated isoforms of alpha-dystrobrevin: roles in skeletal muscle and its neuromuscular and myotendinous junctions. J Cell Biol 2003; 160:741-52. [PMID: 12604589 PMCID: PMC2173352 DOI: 10.1083/jcb.200209045] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
alpha-Dystrobrevin (DB), a cytoplasmic component of the dystrophin-glycoprotein complex, is found throughout the sarcolemma of muscle cells. Mice lacking alphaDB exhibit muscular dystrophy, defects in maturation of neuromuscular junctions (NMJs) and, as shown here, abnormal myotendinous junctions (MTJs). In normal muscle, alternative splicing produces two main alphaDB isoforms, alphaDB1 and alphaDB2, with common NH2-terminal but distinct COOH-terminal domains. alphaDB1, whose COOH-terminal extension can be tyrosine phosphorylated, is concentrated at the NMJs and MTJs. alphaDB2, which is not tyrosine phosphorylated, is the predominant isoform in extrajunctional regions, and is also present at NMJs and MTJs. Transgenic expression of either isoform in alphaDB-/- mice prevented muscle fiber degeneration; however, only alphaDB1 completely corrected defects at the NMJs (abnormal acetylcholine receptor patterning, rapid turnover, and low density) and MTJs (shortened junctional folds). Site-directed mutagenesis revealed that the effectiveness of alphaDB1 in stabilizing the NMJ depends in part on its ability to serve as a tyrosine kinase substrate. Thus, alphaDB1 phosphorylation may be a key regulatory point for synaptic remodeling. More generally, alphaDB may play multiple roles in muscle by means of differential distribution of isoforms with distinct signaling or structural properties.
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MESH Headings
- Alternative Splicing/genetics
- Animals
- Cytoskeletal Proteins/deficiency
- Cytoskeletal Proteins/genetics
- Disease Models, Animal
- Dystrophin-Associated Proteins
- Female
- Immunohistochemistry
- Male
- Membrane Proteins/deficiency
- Membrane Proteins/genetics
- Mice
- Mice, Knockout
- Microscopy, Electron
- Muscle, Skeletal/innervation
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/ultrastructure
- Muscular Dystrophy, Animal/genetics
- Muscular Dystrophy, Animal/metabolism
- Neuromuscular Junction/metabolism
- Neuromuscular Junction/ultrastructure
- Phosphorylation
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Receptors, Cholinergic/metabolism
- Receptors, Cholinergic/ultrastructure
- Recombinant Fusion Proteins
- Sarcolemma/metabolism
- Sarcolemma/ultrastructure
- Synaptic Membranes/genetics
- Synaptic Membranes/metabolism
- Tendons/metabolism
- Tendons/ultrastructure
- Tyrosine/metabolism
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Affiliation(s)
- R Mark Grady
- Dept. of Pediatrics, Washington University School of Medicine, Pediatric Research Bldg., St. Louis, MO 63110, USA.
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Kulyte A, Navakauskiene R, Treigyte G, Gineitis A, Bergman T, Magnusson KE. Characterization of human alpha-dystrobrevin isoforms in HL-60 human promyelocytic leukemia cells undergoing granulocytic differentiation. Mol Biol Cell 2002; 13:4195-205. [PMID: 12475945 PMCID: PMC138626 DOI: 10.1091/mbc.e02-03-0128] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2002] [Revised: 07/30/2002] [Accepted: 09/09/2002] [Indexed: 11/11/2022] Open
Abstract
The biochemical properties and spatial localization of the protein alpha-dystrobrevin and other isoforms were investigated in cells of the human promyelocytic leukemia line HL-60 granulocytic differentiation as induced by retinoic acid (RA). Alpha-dystrobrevin was detected both in the cytosol and the nuclei of these cells, and a short isoform (gamma-dystrobrevin) was modified by tyrosine phosphorylation soon after the onset of the RA-triggered differentiation. Varying patterns of distribution of alpha-dystrobrevin and its isoforms could be discerned in HL-60 promyelocytes, RA-differentiated mature granulocytes, and human neutrophils. Moreover, the gamma-dystrobrevin isoform was found in association with actin and myosin light chain. The results provide new information about potential involvement of alpha-dystrobrevin and its splice isoforms in signal transduction in myeloid cells during induction of granulocytic differentiation and/or at the commitment stage of differentiation or phagocytic cells.
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Affiliation(s)
- Agné Kulyte
- Division of Medical Microbiology, Linköpings Universitet, SE-581 85 Linköping, Sweden.
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15
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Newey SE, Gramolini AO, Wu J, Holzfeind P, Jasmin BJ, Davies KE, Blake DJ. A novel mechanism for modulating synaptic gene expression: differential localization of alpha-dystrobrevin transcripts in skeletal muscle. Mol Cell Neurosci 2001; 17:127-40. [PMID: 11161474 DOI: 10.1006/mcne.2000.0918] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Alpha-dystrobrevin is a dystrophin-related and -associated protein that is involved in synapse maturation and is required for normal muscle function. There are three protein isoforms in skeletal muscle, alpha-dystrobrevin-1, -2, and -3 that are encoded by the single alpha-dystrobrevin gene. To understand the role of these proteins in muscle we have investigated the localisation and transcript distribution of the different alpha-dystrobrevin isoforms. Alpha-dystrobrevin-1 and -2 are concentrated at the neuromuscular junction and are both recruited into agrin-induced acetylcholine receptor clusters in cultured myotubes. We also demonstrate that all alpha-dystrobrevin mRNAs are transcribed from a single promoter in skeletal muscle. However, only transcripts encoding alpha-dystrobrevin-1 are preferentially accumulated at postsynaptic sites. These data suggest that the synaptic accumulation of alpha-dystrobrevin-1 mRNA occurs posttranscriptionally, identifying a novel mechanism for synaptic gene expression. Taken together, these results indicate that different isoforms possess distinct roles in synapse formation and possibly in the pathogenesis of muscular dystrophy.
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Affiliation(s)
- S E Newey
- Department of Human Anatomy and Genetics, MRC Functional Genetics Unit, University of Oxford, South Parks Road, Oxford, OX1 3QX, United Kingdom
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