Spontaneous asj-2 J Mutant Mouse as a Model for Generalized Arterial Calcification of Infancy : A Large Deletion / Insertion Mutation in the Enpp 1 Gene

Generalized arterial calcification of infancy (GACI), an autosomal recessive disorder caused by mutations in the ENPP1 gene, manifests with extensive mineralization of the cardiovascular system. The affected individuals in most cases die within the first year of life, and there is currently no effective treatment for this disorder. In this study, we characterized a spontaneous mutant mouse, asj-2J, as a model for GACI. These mice were identified as part of a phenotypic deviant search in a large-scale production colony of BALB/cJ mice at The Jackson Laboratory. They demonstrated a characteristic gait due to stiffening of the joints, with phenotypic similarity to a previously characterized asj (‘‘ages with stiffened joints’’) mouse, caused by a missense mutation in the Enpp1 gene. Complementation testing indicated that asj-2J and asj were allelic. PCR-based mutation detection strategy revealed in asj-2J mice a large, 40,035 bp, deletion spanning from intron 1 to the 39-untranslated region of the Enpp1 gene, coupled with a 74 bp insertion. This was accompanied with a significant reduction in the plasma PPi concentration and reduced PPi/Pi ratio. As a consequence, extensive aberrant mineralization affecting the arterial vasculature, a number of internal organs, and the dermal sheath of vibrissae, a progressive biomarker of the ectopic mineralization process, was demonstrated by a combination of micro computed tomography, histopathology with calcium-specific stains, and direct chemical assay of calcium. Comparison of the asj and asj-2J mice demonstrated that the latter ones, particularly when placed on an acceleration diet high in phosphate and low in OPEN ACCESS Citation: Li Q, Pratt CH, Dionne LA, Fairfield H, Karst SY, et al. (2014) Spontaneous asj-2J Mutant Mouse as a Model for Generalized Arterial Calcification of Infancy: A Large Deletion/Insertion Mutation in the Enpp1 Gene. PLoS ONE 9(12): e113542. doi:10.1371/journal.pone. 0113542 Editor: Yin Tintut, Los Angeles, United States of America Received: September 5, 2014 Accepted: October 27, 2014 Published: December 5, 2014 Copyright: 2014 Li et al. This is an openaccess article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper. Funding: This work was supported by National Institutes of Health (NIH)/National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) grants K01 AR064766 (to QL), R21 AR063781 (to JPS), and R01 AR28450 (to JU). This work was also supported by NIH/National Center for Research Resources/Office of Research Infrastructure Programs grants OK010972-35, OD011163-02, RR001183, and RR032339 (The Jackson Laboratory). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. PLOS ONE | DOI:10.1371/journal.pone. 0113542 December 5, 2014 1 / 16 magnesium, had more extensive mineralization. Thus, the asj-2J mouse serves as a novel model for GACI, a currently intractable disorder.