Synucleins in ocular tissues

Synucleins are small proteins associated with neurodegenerative diseases an d some forms of cancer. Most studies of this group of proteins have been di rected to the elucidation of their role in the brain and their connection t o the formation of depositions in brain tissues. Here we describe the local ization of different types of synucleins in ocular tissues. By Western blot analysis, all members of the synuclein family are found in the retina and optic nerve, where their relative ratio varies. The data on immunohistochem ical staining show that different members of the synuclein family have diff erent localizations in ocular tissues. alpha -Synucleins and beta -synuclei ns are present predominantly in the inner plexiform layer, whereas gamma -s ynuclein is in the nerve fiber layer. In transgenic mice overexpressing alp ha -synuclein, a different pattern of localization depending on the promote r used for the expression was observed. In Alzheimer's disease patients, im munohistochemical staining for gamma -synuclein revealed the loss of immuno reactivity in the nerve fiber layer and the nerve fiber layer and the appea rance of immunopositive cells in or near the outer nuclear layer. We conclu de that, in mature eyes, synucleins are present predominantly in the retina and optic nerve, and the immunoreactivity of gamma -synuclein changes spec ifically in the retina of Alzheimer's disease patients. In transgenic mice overexpressing alpha -synuclein, immunopositive deposits in the optic nerve and accumulation of immunoreactivity in specific retinal cells were found. J. Neurosci. Res. 65:68-77, 2001. (C) 2001 Wiley-Liss, Inc.