Abstract:
The Hyp mouse, a model for human X-linked hypophosphatemia (XLH), is characterized by phosphate wasting and defective mineralization. Since osteopontin (OPN) is considered pivotal for biological mineralization, we examined the biosynthesis of OPN in osteoblasts of +/Y and Hyp/Y mice. Immunoprecipitation analyses using a specific antibody to OPN revealed that Hyp/Y and +/Y osteoblasts secrete similar levels of OPN as determined by [35S]-methionine biosynthetic labeling, but a reduced phosphorylation was noted after 32P-PO4 biosynthetic labeling. Northern blot hybridization analysis of +/Y and Hyp/Y mice osteoblast mRNAs, using a cDNA probe for mouse OPN, revealed no difference in the steady state levels of osteopontin mRNA. Analysis of casein kinase II activity in +/Y and Hyp/Y mice osteoblast, kidney, heart and liver membrane fractions revealed that casein kinase II activity in the Hyp/Y mice osteoblasts and kidney is only 35%-50%, respectively, of that of the +/Y mice tissues. The accumulated data are consistent with a post-translation defect in the Hyp/Y mouse osteoblast which results in the under-phosphorylation of osteopontin and subsequent under-mineralization of bone matrix.
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Received: 29 April 1997 / Accepted: 28 May 1997
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Rifas, L., Cheng, SL., Halstead, L. et al. Skeletal Casein Kinase Activity Defect in the HYP Mouse . Calcif Tissue Int 61 , 256 –259 (1997). https://doi.org/10.1007/s002239900331
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DOI: https://doi.org/10.1007/s002239900331