Shiozaki M, Yoshimura K, Shibata M, Koike M, Matsuura N, Uchiyama Y, Gotow T
Laboratory of Cell Biology, College of Nutrition, Koshien University, 10-1 Momijigaoka, Takarazuka, Hyogo 665-0006, Japan.
Neuroscience. 2008 Apr 9;152(4):924-41. doi: 10.1016/j.neuroscience.2008.01.032. Epub 2008 Feb 5.
Klotho mutant mice, defective in the klotho gene, develop multiple age-related disorders with very short lifespans. Introduction of the exogenous klotho gene into these mutant mice leads to an improvement in their phenotypes, while overexpression of this gene in wild-type mice significantly extends their lifespan. These observations suggest that the klotho gene/protein has an anti-aging function. Since there have been only a few reports with some disagreement about results on the CNS of the mutant mice, we tried to clarify whether the CNS neurons generate aging-like features, even in premature stages, using biochemical and morphological approaches. Results obtained from the mutant mice, when compared with wild-type mice, were as follows. Neurofilaments (NFs) were increased significantly in axons, with the subunit proteins showing a significant enhancement in phosphorylation or expression of NF-H or NF-L, respectively. Microtubules in Purkinje cell dendrites were closer to each other, and in the CNS tissue tubulin was unaltered, but microtubule-associated protein (MAP) 2 was significantly reduced in expression. Neuronal cellular organelles were morphologically disordered. Lysosomes, cathepsin D and light chain 3 of MAP1A/B (LC3) were augmented with the appearance of putative autophagy-related structures. Antiapoptotic Bcl-xL and proapoptotic Bax were reduced and enhanced, respectively, and mitogen-activated protein kinase was reduced. Synapse-related proteins and structures were decreased. Neuronal degeneration was evident in hippocampal pyramidal cells, and possibly in Purkinje cells. Astrocytic glial filaments and glial fibrillary acidic protein were increased in density and expression, respectively. Together, the CNS neuronal alterations in klotho mutant mice were quite similar to those found in aged animals, including even premature death, so this mouse should be a more appropriate animal model for CNS aging than those previously reported.
在klotho基因上存在缺陷的Klotho突变小鼠会出现多种与年龄相关的疾病，寿命也非常短。将外源性klotho基因导入这些突变小鼠可改善其表型，而在野生型小鼠中过表达该基因则可显著延长其寿命。这些观察结果表明，klotho基因/蛋白具有抗衰老功能。由于关于突变小鼠中枢神经系统的研究结果仅有少数报道且存在一些分歧，我们试图通过生化和形态学方法来阐明中枢神经系统神经元是否即使在早期阶段也会出现类似衰老的特征。与野生型小鼠相比，从突变小鼠获得的结果如下。轴突中的神经丝（NFs）显著增加，其亚基蛋白分别显示出NF-H或NF-L磷酸化或表达的显著增强。浦肯野细胞树突中的微管彼此更靠近，在中枢神经系统组织中微管蛋白未改变，但微管相关蛋白（MAP）2的表达显著降低。神经元细胞器在形态上紊乱。溶酶体、组织蛋白酶D和MAP1A/B的轻链3（LC3）增加，并出现了假定的自噬相关结构。抗凋亡的Bcl-xL减少，促凋亡的Bax增加，丝裂原活化蛋白激酶减少。与突触相关的蛋白和结构减少。海马锥体细胞以及可能还有浦肯野细胞中出现明显的神经元变性。星形胶质细胞的胶质丝和胶质纤维酸性蛋白的密度和表达分别增加。总之，Klotho突变小鼠中枢神经系统神经元的改变与老年动物中发现的改变非常相似，甚至包括过早死亡，因此这种小鼠应该是比先前报道的更适合用于中枢神经系统衰老研究的动物模型。
