Fournier Dale E, Beaucage Kim L, Beach Ryan J, Kiser Patti K, Séguin Cheryle A, Dixon S Jeffrey
Health and Rehabilitation Sciences, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada.
Bone and Joint Institute, The University of Western Ontario, London, Ontario, Canada.
Bone Rep. 2021 Jun 18;15:101100. doi: 10.1016/j.bonr.2021.101100. eCollection 2021 Dec.
Equilibrative nucleoside transporter 1 (ENT1) transfers nucleosides, such as adenosine, across plasma membranes. We reported previously that mice lacking ENT1 ( ) exhibit progressive ectopic calcification of spinal tissues-a phenotype resembling diffuse idiopathic skeletal hyperostosis (DISH) in humans. Our objective was to investigate potential calcification of orofacial tissues in mice. Heads of wild-type mice and mice from 3 to 17 months were evaluated using microcomputed tomography (μCT). Some heads were decalcified and processed for histological assessment. Other heads were examined using energy dispersive X-ray spectroscopy and micro X-ray diffraction. Using μCT, mice showed extensive radiopaque lesions within the mandibular symphysis, the severity of which increased with advancing age. Histologically, at 6 months these ectopic radiopacities were found to correspond to acellular, amorphous, eosinophilic material, with no evidence of inflammatory cells. Because lesions were localised to the symphysis, we identified early pathological changes at 3 months and observed that lesions initiated specifically within the fibrocartilage pad. Energy-dispersive X-ray spectroscopy of ectopic lesions revealed large amounts of calcium and phosphorous in a molar ratio of ~1.59, and X-ray diffraction profiles matched that of calcium-deficient hydroxyapatite. This is the first characterisation of ectopic calcifications within the mandibular symphysis of mice, indicating a role for ENT1 and adenosine metabolism in regulating calcification of fibrocartilaginous tissues. Moreover, these murine lesions resemble areas of dystrophic calcification in the spinal tissues of humans with DISH. Importantly, ectopic calcifications develop in a reproducible temporal pattern within a well-defined anatomical region and, thus, provide a model for determining the cellular and molecular pathways underlying ectopic calcification in DISH and related disorders.
平衡核苷转运体1（ENT1）可将核苷（如腺苷）转运穿过质膜。我们之前报道过，缺乏ENT1的小鼠会出现脊髓组织渐进性异位钙化，这种表型类似于人类的弥漫性特发性骨肥厚（DISH）。我们的目的是研究ENT1基因敲除小鼠口腔面部组织的潜在钙化情况。使用微型计算机断层扫描（μCT）对3至17个月大的野生型小鼠和ENT1基因敲除小鼠的头部进行评估。一些头部进行脱钙处理并用于组织学评估。其他头部则使用能量色散X射线光谱法和微X射线衍射法进行检查。使用μCT检查发现，ENT1基因敲除小鼠的下颌联合处有广泛的不透射线病变，且病变严重程度随年龄增长而增加。组织学检查显示，在6个月大时，这些异位不透射线区域对应于无细胞、无定形、嗜酸性物质，未发现炎症细胞迹象。由于病变局限于联合处，我们在3个月时发现了早期病理变化，并观察到病变 specifically 在纤维软骨垫内开始。对异位病变进行能量色散X射线光谱分析发现，其中含有大量钙和磷，摩尔比约为1.59，X射线衍射图谱与缺钙羟基磷灰石相匹配。这是首次对ENT1基因敲除小鼠下颌联合处的异位钙化进行表征，表明ENT1和腺苷代谢在调节纤维软骨组织钙化中发挥作用。此外，这些小鼠病变类似于患有DISH的人类脊髓组织中的营养不良性钙化区域。重要的是，异位钙化在一个明确界定的解剖区域内以可重复的时间模式发展，因此为确定DISH及相关疾病中异位钙化的细胞和分子途径提供了一个模型。 （注：原文中“specifically”一词疑似有误，根据语境推测可能是“specifically”，翻译为“具体地”“特定地”等，但不明确准确含义，故保留原文形式）
