Department of Neuroscience, Università Politecnica delle Marche, Ancona, Italy.
Neuroscience. 2010 Feb 3;165(3):934-43. doi: 10.1016/j.neuroscience.2009.11.009. Epub 2009 Nov 10.
To define whether cortical glutamatergic and GABAergic release machineries can be differentiated on the basis of the nature and amount of proteins they express, we studied the degree of co-localization of synaptogyrin (SGYR) 1 and 3, vesicle-associated membrane protein (VAMP) 1 and 2, syntaxin (STX) 1A and 1B in vesicular glutamate transporter (VGLUT)1-, VGLUT2- and vesicular GABA transporter (VGAT)-positive (+) puncta and synaptic vesicles in the rat cerebral cortex. Co-localization studies showed that SGYR1 and 3 were expressed in about 90% of VGLUT1+, 70% of VGLUT2+ and 80% of VGAT+ puncta; VAMP1 was expressed in approximately 45% of VGLUT1+, 55% of VGLUT2+, and 80% of VGAT+ puncta; VAMP2 in about 95% of VGLUT1+, 75% of VGLUT2+, and 80% of VGAT+ puncta; STX1A in about 65% of VGLUT1+, 30% of VGLUT2+, and 3% of VGAT+ puncta, and STX1B in approximately 45% of VGLUT1+, 35% of VGLUT2+, and 70% of VGAT+ puncta. Immunoisolation studies showed that while STX1A was completely segregated and virtually absent from VGAT synaptic vesicles, STX1B, VAMP1/VAMP2, SGYR1/SGYR3 showed a similar pattern with the highest expression in VGLUT1 immunoisolated vesicles and the lowest in VGAT immunoisolated vesicles. Moreover, we studied the localization of STX1B at the electron microscope and found that a population of axon terminals forming symmetric synapses were STX1B-positive.These results extend our previous observations on the differential expression of presynaptic proteins involved in neurotransmitter release in GABAergic and glutamatergic terminals and indicate that heterogeneity of glutamatergic and GABAergic release machinery can be contributed by both the presence or absence of a given protein in a nerve terminal and the amount of protein expressed by synaptic vesicles.
为了确定皮质谷氨酸能和 GABA 能释放机制是否可以根据其表达的蛋白质的性质和数量来区分，我们研究了突触糖蛋白（SGYR）1 和 3、囊泡相关膜蛋白（VAMP）1 和 2、突触蛋白（STX）1A 和 1B 在囊泡谷氨酸转运体（VGLUT）1+、VGLUT2+和囊泡 GABA 转运体（VGAT）+阳性（+） puncta 和突触小泡中的共定位程度。共定位研究表明，SGYR1 和 3 表达于约 90%的 VGLUT1+、70%的 VGLUT2+和 80%的 VGAT+ puncta；VAMP1 表达于约 45%的 VGLUT1+、55%的 VGLUT2+和 80%的 VGAT+ puncta；VAMP2 表达于约 95%的 VGLUT1+、75%的 VGLUT2+和 80%的 VGAT+ puncta；STX1A 表达于约 65%的 VGLUT1+、30%的 VGLUT2+和 3%的 VGAT+ puncta，而 STX1B 表达于约 45%的 VGLUT1+、35%的 VGLUT2+和 70%的 VGAT+ puncta。免疫分离研究表明，虽然 STX1A 完全分离且几乎不存在于 VGAT 突触小泡中，但 STX1B、VAMP1/VAMP2、SGYR1/SGYR3 表现出相似的模式，在 VGLUT1 免疫分离小泡中表达最高，在 VGAT 免疫分离小泡中表达最低。此外，我们在电子显微镜下研究了 STX1B 的定位，发现形成对称突触的轴突末梢群体为 STX1B 阳性。这些结果扩展了我们之前关于 GABA 能和谷氨酸能末梢中参与神经递质释放的突触前蛋白的差异表达的观察，并表明谷氨酸能和 GABA 能释放机制的异质性可以由神经末梢中特定蛋白质的存在或缺失以及突触小泡中表达的蛋白质的量来贡献。
