Male Lrp5A214V mice maintain high bone mass during dietary calcium restriction by altering the vitamin D endocrine system.

Autor:	Ozgurel SU; Department of Nutritional Sciences, University of Texas, Austin, TX 78723, United States., Reyes Fernandez PC; Department of Physical Therapy, Indiana University -Purdue University, Indianapolis, IN 46202, United States., Chanpaisaeng K; National Center for Genetic Engineering and Biotechnology, Pathum Thani 12120, Thailand.; Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand., Fleet JC; Department of Nutritional Sciences, University of Texas, Austin, TX 78723, United States.
Jazyk:	angličtina
Zdroj:	Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research [J Bone Miner Res] 2024 Apr 19; Vol. 39 (3), pp. 315-325.
DOI:	10.1093/jbmr/zjae011
Abstrakt:	Environmental factors and genetic variation individually impact bone. However, it is not clear how these factors interact to influence peak bone mass accrual. Here we tested whether genetically programmed high bone formation driven by missense mutations in the Lrp5 gene (Lrp5A214V) altered the sensitivity of mice to an environment of inadequate dietary calcium (Ca) intake. Weanling male Lrp5A214V mice and wildtype littermates (control) were fed AIN-93G diets with 0.125%, 0.25%, 0.5% (reference, basal), or 1% Ca from weaning until 12 weeks of age (ie, during bone growth). Urinary Ca, serum Ca, Ca regulatory hormones (PTH, 1,25 dihydroxyvitamin D3 (1,25(OH)2D3)), bone parameters (μCT, ash), and renal/intestinal gene expression were analyzed. As expected, low dietary Ca intake negatively impacted bones and Lrp5A214V mice had higher bone mass and ash content. Although bones of Lrp5A214V mice have more matrix to mineralize, their bones were not more susceptible to low dietary Ca intake. In control mice, low dietary Ca intake exerted expected effects on serum Ca (decreased), PTH (increased), and 1,25(OH)2D3 (increased) as well as their downstream actions (ie, reducing urinary Ca, increasing markers of intestinal Ca absorption). In contrast, Lrp5A214V mice had elevated serum Ca with a normal PTH response but a blunted 1,25(OH)2D3 response to low dietary Ca that was reflected in the renal 1,25(OH)2D3 producing/degrading enzymes, Cyp27b1 and Cyp24a1. Despite elevated serum Ca in Lrp5A214V mice, urinary Ca was not elevated. Despite an abnormal serum 1,25(OH)2D3 response to low dietary Ca, intestinal markers of Ca absorption (Trpv6, S100g mRNA) were elevated in Lrp5A214V mice and responded to low Ca intake. Collectively, our data indicate that the Lrp5A214V mutation induces changes in Ca homeostasis that permit mice to retain more Ca and support their high bone mass phenotype. (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society for Bone and Mineral Research. All rights reserved. For permissions, please email: journals.permissions@oup.com.)
Databáze:	MEDLINE
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