Calingasan N Y, Sheu K F, Baker H, Jung E H, Paoletti F, Gibson G E
Cornell University Medical College, Burke Medical Research Institute, White Plains, New York 10605.
J Neurochem. 1995 Mar;64(3):1034-44. doi: 10.1046/j.1471-4159.1995.64031034.x.
Transketolase (TK; EC 2.2.1.1) is a key pentose phosphate shunt enzyme that plays an important role in the production of reducing equivalents and pentose sugars. TK activity declines in the brains of patients with Alzheimer's disease or Wernicke-Korsakoff syndrome, as well as in thiamine-deficient rats. Understanding the role of TK in the pathophysiology of these neurodegenerative conditions requires knowledge of its regional, cellular, and subcellular distribution within the brain. The current study employed in situ hybridization and immunocytochemistry to examine the distribution of TK mRNA and its encoded protein in adult rat brain. TK mRNA and protein were widely distributed throughout the brain. However, they were enriched in selective perikarya in the piriform cortex, nucleus of the diagonal band, red nucleus, dorsal raphe, pontine nucleus, locus coeruleus, trapezoid, inferior olive, and several cranial nerve nuclei. Lower expression of TK mRNA and protein occurred in layer V of cortex, olfactory tubercle, ventral pallidum, medial septal nucleus, hippocampus, thalamic and hypothalamic nuclei, mammillary body, central gray, and the substantia nigra. TK immunoreactivity also occurred in the nuclei of ubiquitously distributed glial cells, as well as ependymal cells. The heterogeneous distribution of TK may reflect a variety of metabolic activities among different brain regions but does not provide a simple molecular explanation for selective cell death in either thiamine deficiency or other conditions where TK is reduced.
转酮醇酶（TK；EC 2.2.1.1）是戊糖磷酸支路的关键酶，在还原当量和戊糖的产生中起重要作用。在阿尔茨海默病或韦尼克-科尔萨科夫综合征患者的大脑中，以及硫胺素缺乏的大鼠中，TK活性会下降。了解TK在这些神经退行性疾病病理生理学中的作用需要知晓其在脑内的区域、细胞和亚细胞分布情况。当前研究采用原位杂交和免疫细胞化学方法来检测成年大鼠脑中TK mRNA及其编码蛋白的分布。TK mRNA和蛋白在全脑广泛分布。然而，它们在梨状皮质、斜角带核、红核、中缝背核、脑桥核、蓝斑、斜方体、下橄榄核和几个脑神经核中的选择性核周体中富集。在皮质第V层、嗅结节、腹侧苍白球、内侧隔核、海马、丘脑和下丘脑核、乳头体、中央灰质和黑质中，TK mRNA和蛋白的表达较低。TK免疫反应性也出现在广泛分布的神经胶质细胞以及室管膜细胞的细胞核中。TK的异质性分布可能反映了不同脑区之间的多种代谢活动，但并未为硫胺素缺乏或其他TK减少的情况下的选择性细胞死亡提供一个简单的分子解释。
