Catsicas S, Catsicas M, Keyser K T, Karten H J, Wilson M C, Milner R J
Department of Neuropharmacology, Scripps Research Institute, La Jolla.
J Neurosci Res. 1992 Sep;33(1):1-9. doi: 10.1002/jnr.490330102.
We have studied the expression of the nerve terminal protein synaptosomal associated protein 25 (SNAP-25) in the retina of adult rat, mouse, and monkey, as well as in the developing mouse retina. To evaluate SNAP-25 expression, its distribution was compared to those of the synaptic vesicle-associated proteins synapsin I and synaptophysin. In situ hybridization in adult rat retinas suggested that SNAP-25 mRNA is mainly expressed by ganglion, amacrine, and horizontal cells, but not by photoreceptors and bipolar cells. In all species, the SNAP-25 polypeptide was most abundant in the inner part of the inner and outer plexiform layers and was also found in the ganglion cell axons. In adult retina, synapsin I and synaptophysin were also mainly localized in synaptic fields and processes but all three proteins showed a distinct pattern of distribution. Finally, in mouse retina, the three proteins were first detectable at embryonic day 16 and subsequently showed developmentally regulated changes in their cellular localization. These results suggest that SNAP-25 is predominantly expressed in specific subtypes of conventional synapses, but not ribbon synapses, and that it may also be involved in the physiology of nonvesicular terminals of horizontal cells. Our study also suggests that combinatorial expression of different components of the presynaptic specialization may contribute to synaptic functional diversity.
我们研究了神经末梢蛋白突触体相关蛋白25（SNAP - 25）在成年大鼠、小鼠和猴子视网膜以及发育中小鼠视网膜中的表达。为评估SNAP - 25的表达，将其分布与突触囊泡相关蛋白突触素I和突触素进行了比较。成年大鼠视网膜的原位杂交表明，SNAP - 25 mRNA主要由神经节细胞、无长突细胞和水平细胞表达，而光感受器细胞和双极细胞不表达。在所有物种中，SNAP - 25多肽在内外网状层的内部最为丰富，在神经节细胞轴突中也有发现。在成年视网膜中，突触素I和突触素也主要定位于突触区域和突触过程，但这三种蛋白显示出不同的分布模式。最后，在小鼠视网膜中，这三种蛋白在胚胎第16天首次可检测到，随后在细胞定位上呈现出发育调控的变化。这些结果表明，SNAP - 25主要在传统突触的特定亚型中表达，而非带状突触，并且它可能也参与水平细胞非囊泡末梢的生理过程。我们的研究还表明，突触前特化不同成分的组合表达可能有助于突触功能多样性。
