Gonatas J O, Stieber A, Gonatas N K, Messing A
Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, 418 Johnson Pavilion, 36 Hamilton Walk, Philadelphia, PA 19104-6079, USA.
Brain Res. 2000 Feb 7;855(1):23-31. doi: 10.1016/s0006-8993(99)02037-5.
The Golgi apparatus (GA) of innervated rat and chicken skeletal muscle is present in a typical perinuclear location, and in subsynaptic areas where it disperses after denervation. It was suggested that the subsynaptic segments of the GA are linked with functions involved in the maturation and targeting of synaptic proteins. Similarly, the GA of rat myocardium is found in a perinuclear location and between myofibrils, adjacent to the T system of tubules. These findings raise the question whether the GA of polarized cells is present in a typical perinuclear location, for the performance of general "housekeeping" functions, and in distal areas, for the mediation of specialized functions. Astrocytes may contain GA within their long cytoplasmic processes which are difficult to identify in thin sections. To ensure the astrocytic origin of GA in otherwise unidentifiable small processes, we used transgenic mice expressing the rat MG160 medial Golgi sialoglycoprotein only in the GA of astrocytes, and visualized the GA with monoclonal antibody 10A8 (mAb10A8) which reacts only with rat MG160. Thus, we identified cisternae of the GA in distal perisynaptic and subependymal processes, in perivascular foot plates of cerebral astrocytes, and in processes of the Müller glia in the retina. A similar strategy may be adopted in future investigations aiming at the detection of elements of the GA in distal processes of neurons and oligodendrocytes. The functional implications of GA in perisynaptic astrocytic processes and other processes are unknown. However, the isolation and molecular characterization of the perisynaptic subset of astrocytic Golgi may be feasible, since others have purified the astrocytic glutamate transporter 1 (GLT1) from crude synaptosomal fractions in which astrocytic processes are probably unavoidable contaminants.
受神经支配的大鼠和鸡骨骼肌中的高尔基体（GA）位于典型的核周位置，以及去神经支配后会分散的突触下区域。有人提出，GA的突触下片段与突触蛋白成熟和靶向相关的功能有关。同样，大鼠心肌中的GA位于核周位置以及肌原纤维之间，与T小管系统相邻。这些发现提出了一个问题，即极化细胞的GA是否既存在于典型的核周位置以执行一般的“内务”功能，又存在于远端区域以介导特殊功能。星形胶质细胞在其长细胞质突起中可能含有GA，而在薄切片中很难识别这些突起。为了确保在其他难以识别的小突起中GA来源于星形胶质细胞，我们使用了仅在星形胶质细胞的GA中表达大鼠MG160内侧高尔基体唾液酸糖蛋白的转基因小鼠，并用仅与大鼠MG160反应的单克隆抗体10A8（mAb10A8）使GA可视化。因此，我们在突触周围和室管膜下远端突起、脑星形胶质细胞的血管周足板以及视网膜中Müller胶质细胞的突起中鉴定出了GA的扁平囊。在未来旨在检测神经元和少突胶质细胞远端突起中GA成分的研究中，可能会采用类似的策略。GA在突触周围星形胶质细胞突起和其他突起中的功能意义尚不清楚。然而，星形胶质细胞高尔基体突触周围亚群的分离和分子特征分析可能是可行的，因为其他人已经从粗制突触体组分中纯化了星形胶质细胞谷氨酸转运体1（GLT1），而在这些组分中星形胶质细胞突起可能是不可避免的污染物。
