Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.
Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
Purinergic Signal. 2021 Jun;17(2):241-246. doi: 10.1007/s11302-021-09784-9. Epub 2021 Apr 15.
Transgenic and knockout animal models are widely used to investigate the role of receptors, signaling pathways, and other peptides and proteins. Varying results are often published on the same model from different groups, and much effort has been put into understanding the underlying causes of these sometimes conflicting results. Recently, it has been shown that a P2X4R knockout model carries a so-called passenger mutation in the P2X7R gene, potentially affecting the interpretation of results from studies using this animal model. We therefore report this case to raise awareness about the potential pitfalls using genetically modified animal models, especially within P2 receptor research. Although purinergic signaling has been recognized as an important contributor to the regulation of bone remodeling, the process that maintains the bone quality during life, little is known about the role of the P2X4 receptor (P2X4R) in regulation of bone remodeling in health and disease. To address this, we analyzed the bone phenotype of P2rx4tm1Rass (C57BL/6J) knockout mice and corresponding wildtype using microCT and biomechanical testing. Overall, we found that the P2X4R knockout mice displayed improved bone microstructure and stronger bones in an age- and gender-dependent manner. While cortical BMD, trabecular BMD, and bone volume were higher in the 6-month-old females and 3-month-old males, this was not the case for the 3-month-old females and the 6-month-old males. Bone strength was only affected in the females. Moreover, we found that P2X4R KO mice carried the P2X7 receptor 451P wildtype allele, whereas the wildtype mice carried the 451L mutant allele. In conclusion, this study suggests that P2X4R could play a role in bone remodeling, but more importantly, it underlines the potential pitfalls when using knockout models and highlights the importance of interpreting results with great caution. Further studies are needed to verify any specific effects of P2X4R on bone metabolism.
转基因和基因敲除动物模型被广泛用于研究受体、信号通路和其他肽和蛋白质的作用。不同的研究小组经常在同一模型上发表不同的结果，并且已经投入了大量的精力来理解这些有时相互矛盾的结果的潜在原因。最近，已经表明 P2X4R 基因敲除模型携带 P2X7R 基因的所谓“乘客突变”，这可能会影响使用这种动物模型进行的研究结果的解释。因此，我们报告了这一案例，以提高人们对使用基因修饰动物模型的潜在陷阱的认识，特别是在 P2 受体研究中。尽管嘌呤能信号已被认为是调节骨重塑的重要因素，而骨重塑是维持生命期间骨质量的过程，但对于 P2X4 受体（P2X4R）在健康和疾病中调节骨重塑的作用知之甚少。为了解决这个问题，我们使用 microCT 和生物力学测试分析了 P2rx4tm1Rass（C57BL/6J）基因敲除小鼠及其相应的野生型的骨表型。总体而言，我们发现 P2X4R 基因敲除小鼠在年龄和性别依赖性的方式下表现出改善的骨微结构和更强的骨骼。虽然 6 月龄雌性和 3 月龄雄性的皮质骨密度、小梁骨密度和骨体积较高，但 3 月龄雌性和 6 月龄雄性的情况并非如此。只有雌性的骨强度受到影响。此外，我们发现 P2X4R KO 小鼠携带 P2X7 受体 451P 野生型等位基因，而野生型小鼠携带 451L 突变型等位基因。总之，这项研究表明 P2X4R 可能在骨重塑中发挥作用，但更重要的是，它强调了使用基因敲除模型时的潜在陷阱，并强调了谨慎解释结果的重要性。需要进一步的研究来验证 P2X4R 对骨代谢的任何特定影响。
