Localization of alpha integrin subunits in the neural retina of the tiger salamander.
BACKGROUND
Integrin receptors mediate cell-extracellular matrix interactions and regulate many events, including cell growth, proliferation, and differentiation. Retinal integrins are incompletely understood, although these receptors are potentially important factors in normal retinal function and pathology.


METHODS
Immunocytochemistry was used to localize alpha integrin subunits 1-6 in the neural retina.


RESULTS
Each alpha integrin subunit had a unique distribution in the retina, although there was considerable overlap among subunits. The alpha 1 subunit was broadly distributed throughout the retina, with some presumptive ganglion cells showing enriched labeling. The alpha 2 subunit was present on all retinal cell bodies, but was reduced in synaptic layers. The alpha 3 subunit was present in synaptic layers, Müller cells, and some cone and amacrine cells. The alpha 4 subunit was broadly distributed in the nuclear layers but was reduced in synaptic layers. The alpha 5 subunit was broadly expressed in the nuclear and synaptic layers with enriched labeling in the outer plexiform layer. Labeling for the alpha 6 subunit was restricted to the outer limiting membrane and some cone outer segments. Double-labeling studies indicated that photoreceptor terminals may exhibit alpha 1 and alpha 5 subunits, while processes from second-order neurons may exhibit alpha 1, alpha 3, and alpha 5 subunits.


CONCLUSIONS
Integrin receptors containing the alpha 1, alpha 3, and alpha 5 subunits may have important functions at retinal synapses, in addition to roles in the nuclear layers. Integrin receptors containing alpha 2, alpha 4, and alpha 6 subunits probably serve non-synaptic functions.
Sherry
D M
DM
University of Houston, College of Optometry, 505 J Davis Armistead Bldg, Houston, TX 77204-2020, USA. dsherry@mail-gw.opt.uh.edu
Proske
P A
PA
D000557:Ambystoma; D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis; D019084:Fluorescent Antibody Technique, Indirect; D039423:Integrin alpha1; D039421:Integrin alpha2; D039422:Integrin alpha3; D039441:Integrin alpha4; D039482:Integrin alpha5; D039503:Integrin alpha6; D016023:Integrins / Q000032:analysis*; D008856:Microscopy, Fluorescence; D012160:Retina / Q000737:chemistry*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D039423:Integrin alpha1; D039421:Integrin alpha2; D039422:Integrin alpha3; D039482:Integrin alpha5; D039503:Integrin alpha6; D016023:Integrins; D039441:Integrin alpha4