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J. Biol. Chem., Vol. 281, Issue 25, 99920, June 23, 2006

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Boning Up on Vitamin K2 Function

Vitamin K2 promotes collagen expression in osteoblastic cells.

Vitamin K₂ (2-methyl-3-hexaprenyl-1,4-naphthoquinone) is an essential nutrient that has many functions including a role in bone formation. Supplementation with the vitamin enhances the expression of bone markers, increases bone density in vivo, and is used clinically in the management of osteoporosis. Vitamin K₂ was originally thought to contribute to bone formation via a role as an essential cofactor for -carboxylation of bone matrix proteins. More recent evidence suggests that the vitamin also has a transcriptional regulatory role arising from an ability to bind to and activate the steroid and xenobiotic receptor SXR and induce expression of target genes.

To further explore the SXR-mediated vitamin K₂ signaling network, Ichikawa and colleagues used DNA microarrays to identify three genes with increased expression in osteoblastic cell lines treated with vitamin K₂ and the classic SXR ligand rifampicin. Transfection and siRNA experiments showed that one of the three responsive genes, tsukushi, contributed to enhanced collagen accumulation. These results suggest a new function for vitamin K₂ in bone formation as a transcriptional regulator of extracellular matrix-related genes involved in collagen assembly.

FOOTNOTES

See referenced article, J. Biol. Chem. 2006, 281, 16927-16934

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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content Related Collections Papers Of The Week Social Bookmarking                      What's this?