Al-Jazzar Ahmed, Javaheri Behzad, Prideaux Matt, Boyde Alan, Scudamore Cheryl L, Cherifi Chahrazad, Hay Eric, Hopkinson Mark, Boyd Michael, Cohen-Solal Martine, Farquharson Colin, Pitsillides Andrew A
Skeletal Biology Group, Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, UK.
Orthopaedics & Trauma, University of Adelaide, Adelaide, SA 5005, Australia.
Int J Mol Sci. 2016 Dec 26;18(1):29. doi: 10.3390/ijms18010029.
Mice harbouring a dentin matrix protein 1 () promoter-driven human diphtheria toxin (DT) receptor () transgene (Tg) have recently been used to attain targeted ablation of osteocytes by diphtheria toxin (DT) treatment in order to define osteocyte function. Use of these Tg mice has asserted mechano- and novel paracrine regulatory osteocyte functions. To explore osteocyte roles fully, we sought to confirm the selectivity of DT effects in these transgenic mice. However, our findings revealed incomplete DT-induced osteocyte ablation, prevalent misexpression, as well as more prominent histopathological DT-induced changes in multiple organs in Tg than in wild-type (WT) littermate mice. Mechanistic evidence for DT action, via prominent regulation of phosphorylation status of elongation factor-2 (EF-2), was also found in many non-skeletal tissues in Tg mice; indicative of direct "off-target" DT action. Finally, very rapid deterioration in health and welfare status in response to DT treatment was observed in these Tg when compared to WT control mice. Together, these data lead us to conclude that alternative models for osteocyte ablation should be sought and caution be exercised when drawing conclusions from experiments using these Tg mice alone.
携带牙本质基质蛋白1（DMP1）启动子驱动的人白喉毒素（DT）受体（hDTR）转基因（Tg）的小鼠最近被用于通过白喉毒素（DT）处理实现骨细胞的靶向消融，以确定骨细胞的功能。这些Tg小鼠的使用证实了机械和新的旁分泌调节骨细胞功能。为了全面探索骨细胞的作用，我们试图证实DT在这些转基因小鼠中的作用选择性。然而，我们的研究结果显示DT诱导的骨细胞消融不完全、普遍存在错误表达，并且与野生型（WT）同窝小鼠相比，Tg小鼠多个器官中DT诱导的组织病理学变化更明显。在Tg小鼠的许多非骨骼组织中也发现了DT作用的机制证据，即通过显著调节延伸因子-2（EF-2）的磷酸化状态；这表明DT存在直接的“脱靶”作用。最后，与WT对照小鼠相比，这些Tg小鼠在接受DT处理后健康和福利状况迅速恶化。总之，这些数据使我们得出结论，应该寻找替代的骨细胞消融模型，并且在仅使用这些Tg小鼠进行实验得出结论时应谨慎行事。
