Microarray Profiling of Diaphyseal Bone of Rats Suffering from Hypervitaminosis A
2012 (English)In: Calcified Tissue International, ISSN 0171-967X, E-ISSN 1432-0827, Vol. 90, no 3, 219-229 p.Article in journal (Refereed) Published
Vitamin A is the only known compound that produces spontaneous fractures in rats. In an effort to resolve the molecular mechanism behind this effect, we fed young male rats high doses of vitamin A and performed microarray analysis of diaphyseal bone with and without marrow after 1 week, i.e., just before the first fractures appeared. Of the differentially expressed genes in cortical bone, including marrow, 98% were upregulated. In contrast, hypervitaminotic cortical bone without marrow showed reduced expression of 37% of differentially expressed genes. Gene ontology (GO) analysis revealed that only samples containing bone marrow were associated with a GO term, which principally represented extracellular matrix. This is consistent with the histological findings of increased endosteal/marrow osteoblast number. Fourteen genes, including Cyp26b1, which is known to be upregulated by vitamin A, were selected and verified by real-time PCR. In addition, immunohistochemical staining of bone sections confirmed that the bone-specific molecule osteoadherin was upregulated. Further analysis of the major gene-expression changes revealed apparent augmented Wnt signaling in the sample containing bone marrow but reduced Wnt signaling in cortical bone. Moreover, induced expression of hypoxia-associated genes was found only in samples containing bone marrow. Together, these results highlight the importance of compartment-specific analysis of bone and corroborate previous observations of compartment-specific effects of vitamin A, with reduced activity in cortical bone but increased activity in the endosteal/marrow compartment. We specifically identify potential key osteoblast-, Wnt signaling-, and hypoxia-associated genes in the processes leading to spontaneous fractures.
Place, publisher, year, edition, pages
2012. Vol. 90, no 3, 219-229 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-165522DOI: 10.1007/s00223-011-9561-6ISI: 000301796200007PubMedID: 22215263OAI: oai:DiVA.org:uu-165522DiVA: diva2:474071