Hartmann Dieter, de Strooper Bart, Serneels Lutgarde, Craessaerts Katleen, Herreman An, Annaert Wim, Umans Lieve, Lübke Torben, Lena Illert Anna, von Figura Kurt, Saftig Paul
Center for Human Genetics KU Leuven and Flanders Interuniversity Institute for Biotechnology, VIB 4 KU Leuven, VIB 7 (Celgen), Herestraat 49, 3000 Leuven, Belgium.
Hum Mol Genet. 2002 Oct 1;11(21):2615-24. doi: 10.1093/hmg/11.21.2615.
The metalloprotease ADAM 10 is an important APP alpha-secretase candidate, but in vivo proof of this is lacking. Furthermore, invertebrate models point towards a key role of the ADAM 10 orthologues Kuzbanian and sup-17 in Notch signalling. In the mouse, this function is, however, currently attributed to ADAM 17/TACE, while the role of ADAM 10 remains unknown. We have created ADAM 10-deficient mice. They die at day 9.5 of embryogenesis with multiple defects of the developing central nervous system, somites, and cardiovascular system. In situ hybridization revealed a reduced expression of the Notch target gene hes-5 in the neural tube and an increased expression of the Notch ligand dll-1, supporting an important role for ADAM 10 in Notch signalling in the vertebrates as well. Since the early lethality precluded the establishment of primary neuronal cultures, APPs alpha generation was analyzed in embryonic fibroblasts and found to be preserved in 15 out of 17 independently generated ADAM 10-deficient fibroblast cell lines, albeit at a quantitatively more variable level than in controls, whereas a severe reduction was found in only two cases. The variability was not due to differences in genetic background or to variable expression of the alternative alpha-secretase candidates ADAM 9 and ADAM 17. These results indicate, therefore, either a regulation between ADAMs on the post-translational level or that other, not yet known, proteases are able to compensate for ADAM 10 deficiency. Thus, the observed variability, together with recent reports on tissue-specific expression patterns of ADAMs 9, 10 and 17, points to the existence of tissue-specific 'teams' of different proteases exerting alpha-secretase activity.
金属蛋白酶ADAM 10是淀粉样前体蛋白（APP）α-分泌酶的一个重要候选者，但尚缺乏其体内证据。此外，无脊椎动物模型表明ADAM 10的同源物库兹班安（Kuzbanian）和sup-17在Notch信号传导中起关键作用。然而，在小鼠中，目前该功能归因于ADAM 17/TACE，而ADAM 10的作用仍不清楚。我们构建了ADAM 10基因敲除小鼠。它们在胚胎发育第9.5天死亡，伴有发育中的中枢神经系统、体节和心血管系统的多种缺陷。原位杂交显示神经管中Notch靶基因hes-5的表达降低，而Notch配体dll-1的表达增加，这也支持了ADAM 10在脊椎动物Notch信号传导中起重要作用。由于早期致死性妨碍了原代神经元培养的建立，因此在胚胎成纤维细胞中分析了APPsα的产生，发现在17个独立产生的ADAM 10基因敲除成纤维细胞系中有15个系中其得以保留，尽管其水平在数量上比对照更具变异性，而仅在两例中发现严重降低。这种变异性并非由于遗传背景的差异或替代性α-分泌酶候选者ADAM 9和ADAM 17的可变表达所致。因此，这些结果表明，要么是ADAMs之间在翻译后水平上存在调节，要么是其他尚未知晓的蛋白酶能够补偿ADAM 10的缺陷。因此，观察到的变异性，连同最近关于ADAMs 9、10和17的组织特异性表达模式的报道，表明存在发挥α-分泌酶活性的不同蛋白酶的组织特异性“团队”。
