Urase K, Momoi T, Fujita E, Isahara K, Uchiyama Y, Tokunaga A, Nakayama K, Motoyama N
Division of Development and Differentiation, National Institute of Neuroscience, NCNP, Kodaira, Tokyo 187-8502, Japan.
Brain Res Dev Brain Res. 1999 Aug 5;116(1):69-78. doi: 10.1016/s0165-3806(99)00076-0.
Caspases and Bcl-xL, the mammalian homologues of the Caenorhabditis elegans (C. elegans) ced-3 and ced-9 genes, respectively, regulate apoptosis of various cells. Caspase-3 is processed into an active form (p20 or p17 and p12) during apoptosis. We investigated the relation between caspase-3 and Bcl-xL during development by examining activation of caspase-3 and apoptotic cells in Bcl-x-deficient (bcl-x(-/-)) mice at embryonic (E) day 11.5. We used a double-staining technique with a cleavage site-directed antibody against caspase-3 (anti-p20/17) and terminal-deoxytransferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL). Bcl-xL-deficiency increased both numbers of p20/17-positive and -negative apoptotic cells in dorsal root ganglia (DRG); the numbers of p20/17-positive apoptotic cells in the caudal parts of the ventral hindbrain and ventral spinal cord; and the numbers of p20/17-negative apoptotic cells in the dorsal midbrain, dorsal hindbrain, and dorsal spinal cord. Thus, Bcl-xL blocks the caspase-3-dependent apoptotic pathway in the restricted regions of the nervous system during development. Furthermore, these observations suggest that Bcl-xL protects against activation of the caspase-3-independent apoptotic pathway. Other caspases or apoptotic mechanisms may also be activated in the nervous systems of bcl-x(-/-) mice.
半胱天冬酶和Bcl-xL分别是秀丽隐杆线虫（C. elegans）ced-3和ced-9基因的哺乳动物同源物，它们调节各种细胞的凋亡。在凋亡过程中，半胱天冬酶-3被加工成活性形式（p20或p17和p12）。我们通过检测胚胎（E）第11.5天Bcl-x缺陷（bcl-x(-/-)）小鼠中半胱天冬酶-3的激活情况和凋亡细胞，研究了发育过程中半胱天冬酶-3与Bcl-xL之间的关系。我们使用了一种双重染色技术，即针对半胱天冬酶-3的切割位点定向抗体（抗p20/17）和末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记（TUNEL）。Bcl-xL缺陷增加了背根神经节（DRG）中p20/17阳性和阴性凋亡细胞的数量；后脑腹侧和脊髓腹侧尾部p20/17阳性凋亡细胞的数量；以及中脑背侧、后脑背侧和脊髓背侧p20/17阴性凋亡细胞的数量。因此，在发育过程中，Bcl-xL在神经系统的特定区域阻断了半胱天冬酶-3依赖性凋亡途径。此外，这些观察结果表明，Bcl-xL可防止半胱天冬酶-3非依赖性凋亡途径的激活。其他半胱天冬酶或凋亡机制也可能在bcl-x(-/-)小鼠的神经系统中被激活。
