啮齿动物蓝斑核神经元间缝隙连接中连接蛋白36的鉴定。
Identification of connexin36 in gap junctions between neurons in rodent locus coeruleus.
作者信息
Rash J E, Olson C O, Davidson K G V, Yasumura T, Kamasawa N, Nagy J I
机构信息
Department of Biomedical Sciences, Colorado State University, Campus Delivery 1617, Fort Collins, CO 80523, USA.
出版信息
Neuroscience. 2007 Jul 29;147(4):938-56. doi: 10.1016/j.neuroscience.2007.04.061. Epub 2007 Jul 2.
Locus coeruleus neurons are strongly coupled during early postnatal development, and it has been proposed that these neurons are linked by extraordinarily abundant gap junctions consisting of connexin32 (Cx32) and connexin26 (Cx26), and that those same connexins abundantly link neurons to astrocytes. Based on the controversial nature of those claims, immunofluorescence imaging and freeze-fracture replica immunogold labeling were used to re-investigate the abundance and connexin composition of neuronal and glial gap junctions in developing and adult rat and mouse locus coeruleus. In early postnatal development, connexin36 (Cx36) and connexin43 (Cx43) immunofluorescent puncta were densely distributed in the locus coeruleus, whereas Cx32 and Cx26 were not detected. By freeze-fracture replica immunogold labeling, Cx36 was found in ultrastructurally-defined neuronal gap junctions, whereas Cx32 and Cx26 were not detected in neurons and only rarely detected in glia. In 28-day postnatal (adult) rat locus coeruleus, immunofluorescence labeling for Cx26 was always co-localized with the glial gap junction marker Cx43; Cx32 was associated with the oligodendrocyte marker 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase); and Cx36 was never co-localized with Cx26, Cx32 or Cx43. Ultrastructurally, Cx36 was localized to gap junctions between neurons, whereas Cx32 was detected only in oligodendrocyte gap junctions; and Cx26 was found only rarely in astrocyte junctions but abundantly in pia mater. Thus, in developing and adult locus coeruleus, neuronal gap junctions contain Cx36 but do not contain detectable Cx32 or Cx26, suggesting that the locus coeruleus has the same cell-type specificity of connexin expression as observed ultrastructurally in other regions of the CNS. Moreover, in both developing and adult locus coeruleus, no evidence was found for gap junctions or connexins linking neurons with astrocytes or oligodendrocytes, indicating that neurons in this nucleus are not linked to the pan-glial syncytium by Cx32- or Cx26-containing gap junctions or by abundant free connexons composed of those connexins.
蓝斑神经元在出生后早期发育阶段紧密耦合，有人提出这些神经元通过由连接蛋白32（Cx32）和连接蛋白26（Cx26）组成的极其丰富的缝隙连接相连，并且这些相同的连接蛋白大量地将神经元与星形胶质细胞相连。基于这些说法的争议性，采用免疫荧光成像和冷冻断裂复型免疫金标记技术，重新研究发育中和成年大鼠及小鼠蓝斑中神经元和胶质细胞缝隙连接的丰度及连接蛋白组成。在出生后早期发育阶段，连接蛋白36（Cx36）和连接蛋白43（Cx43）免疫荧光斑点密集分布于蓝斑，而未检测到Cx32和Cx26。通过冷冻断裂复型免疫金标记，在超微结构定义的神经元缝隙连接中发现了Cx36，而在神经元中未检测到Cx32和Cx26，在胶质细胞中仅偶尔检测到。在出生后28天（成年）大鼠蓝斑中，Cx26的免疫荧光标记始终与胶质细胞缝隙连接标记物Cx43共定位；Cx32与少突胶质细胞标记物2'，3'-环核苷酸3'-磷酸二酯酶（CNPase）相关；并且Cx36从未与Cx26、Cx32或Cx43共定位。在超微结构上，Cx36定位于神经元之间的缝隙连接，而Cx32仅在少突胶质细胞缝隙连接中检测到；Cx26仅在星形胶质细胞连接中偶尔发现，但在软脑膜中大量存在。因此，在发育中和成年蓝斑中，神经元缝隙连接含有Cx36，但不含有可检测到的Cx32或Cx26，这表明蓝斑具有与在中枢神经系统其他区域超微结构观察到的相同的连接蛋白表达细胞类型特异性。此外，在发育中和成年蓝斑中，均未发现将神经元与星形胶质细胞或少突胶质细胞相连的缝隙连接或连接蛋白的证据，表明该核团中的神经元并非通过含Cx32或Cx26的缝隙连接或由这些连接蛋白组成的大量游离连接子与全胶质细胞合体相连。
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