Dystrobrevin localization in photoreceptor axon terminals and at blood-ocular barrier sites.
OBJECTIVE
Dystrobrevin is a newly discovered dystrophin-associated protein with multiple sites for phosphorylation on tyrosine residues. In the present study, the cellular distribution and subcellular localization of dystrobrevin were examined in the adult rat retina, cornea, lens, iris, ciliary body, and cultured Müller cells.


METHODS
Immunoblot analysis, confocal laser scanning microscopy, and immunoelectron microscopy were used to examine dystrobrevin expression.


RESULTS
Immunoblot analysis showed that an approximately 87-kDa band was expressed predominantly in the lens, retina, iris and ciliary body, whereas an approximately 60-kDa band was expressed in cultured Müller cells, cornea, retina, iris, and ciliary body. Confocal microscopy demonstrated dystrobrevin in the inner limiting membrane, outer plexiform layer, and retinal pigment epithelium and around blood vessels in the retina. At the ultrastructural level, dystrobrevin was localized under cell membranes of rod spherules and cone pedicles of photoreceptor cell terminals but often was found in the cytoplasm of endothelial cells and Müller cells. Furthermore, dystrobrevin was colocalized with beta-dystroglycan in corneal endothelium; lens, iris, and ciliary epithelia; and cultured Müller cells.


CONCLUSIONS
The present study demonstrates that dystrobrevin is expressed in neurons, glia, and endothelial cells in the rat retina. In addition, dystrobrevin is localized at the blood-ocular barrier sites in extraocular tissue. These data suggest that dystrobrevin plays an important role in visual function.
Ueda
H
H
Departments of Anatomy and. Ophthalmology, Yamanashi Medical University, Japan. hueda@res.yamanashi-med.ac.jp
Baba
T
T
Kashiwagi
K
K
Iijima
H
H
Ohno
S
S
D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000378:metabolism*; D001693:Biological Transport, Active; D001769:Blood / Q000378:metabolism*; D015153:Blotting, Western; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D049030:Dystroglycans; D049029:Dystrophin-Associated Proteins; D005123:Eye / Q000098:blood supply* / Q000378:metabolism / Q000648:ultrastructure; D007124:Immunoenzyme Techniques; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D009479:Neuropeptides / Q000378:metabolism*; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley
D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; C111539:DTNB protein, human; D049029:Dystrophin-Associated Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009479:Neuropeptides; C098885:dystrobrevin; D049030:Dystroglycans