Vitamin K2 promotes 1?,25(OH)2 vitamin D3-induced mineralization in human periosteal osteoblasts

Abstract

The effect of vitamin K on mineralization by human periosteal osteoblasts was investigated in the absence and presence of 1alpha, 25 dihydroxyvitamin D3 (1,25(OH)2D3). Vitamin K1 and K2, but not vitamin K3, at 2.5 microM enhanced in vitro mineralization when cells were cultured with vitamin K for 20 days after reaching confluence in vitro. Vitamin K2 (2-methyl-3-all-trans-tetraphenyl-1, 4-naphthoquinone : menatetrenone) was the most potent of these vitamin K analogs; it slightly inhibited alkaline phosphatase (ALP) activity. Human osteoblasts were mineralized and showed the enhanced ALP activity on treatment with 10(-9) M of 1,25(OH)2D3 for 20 or 25 days after confluence. Vitamin K2 promoted the 1,25(OH)2D3-induced mineralization, but slightly inhibited the 1,25(OH)2D3-induced ALP activity. Moreover, vitamin K2 enhanced the 1,25(OH)2D3-induced osteocalcin accumulation in the cells and the extracellular matrix (cell layer), but inhibited the osteocalcin content in the medium produced by the 1,25(OH)2D3 treatment. However, vitamin K2 alone did not induce osteocalcin production in the human osteoblasts. On Northern blot analysis, osteocalcin mRNA expression on 1, 25(OH)2D3-treated cells was enhanced by vitamin K2 treatment, but vitamin K2 alone did not induce osteocalcin mRNA expression. Warfarin blocked both the 1,25(OH)2D3-induced osteocalcin production and the accumulation in the cell layer, and also blocked the 1, 25(OH)2D3 plus vitamin K2-induced osteocalcin production and the accumulation in the cell layer. The 1,25(OH)2D3-induced mineralization promoted by vitamin K2 was probably due to the enhanced accumulation of osteocalcin induced by vitamin K2 in the cell layer. However, we concluded that the mineralization induced by vitamin K2 alone was due to the accumulation of osteocalcin in bovine serum on the cell layer, since osteocalcin extracted from the cell layer was not identified by specific antiserum against human osteocalcin, which does not cross-react with bovine osteocalcin. These results suggest that the mechanism underlying the mineralization induced by vitamin K2 in the presence of 1,25(OH)2D3 was different from that of vitamin K2 alone, and that osteocalcin plays an important role in mineralization by osteoblasts in vitro.

Effect of vitamin K2 on the development of stress-induced osteopenia in a growing senescence-accelerated mouse prone 6 strain

“…The coronal view of the femoral distal end was observed using Villanueva Bone Staining. Bone histomorphometrical examination was used to evaluate the tissue volume (TV, µm 2 ), bone volume (BV, µm 2 ), bone surface (BS, µm), single-labeled surface, double-labeled surface (dLS, mm), Tb thickness (Tb.Th, µm) and the number of osteoclasts and osteoblasts (N.Ocs and N.Obs, respectively). Obs were further classified into type II-IV according to morphological classification criteria (20): Type II, classical cuboidal or columnar with adjacent nuclear clear zone, type III, intermediate without adjacent nuclear clear zone and type IV, cytoplasm-extremely thin (most mature population) (21).…”

“…Among the VK2 molecules, MK-4 (VK2 with 4 isoprene units) is known to contribute to high γ-carboxylation activity and exhibit the most potent biological activity of the VK2s (2). Previous meta-analyses have demonstrated the anti-fracture effect of VK2 in patients with a high risk of fracture (3,4).…”

Vitamin K: an old vitamin in a new perspective

“…A low dietary vitamin K intake and high proportion of uncarboxylated osteocalcin (ucOC) are independent risk factors for hip fractures. [27][28][29][30] The production and activation of osteocalcin (OC) 33 There is growing evidence about the synergistic effect on bone health of vitamin K and vitamin D. But further data is required in order to have a complete understanding of the complex interaction between vitamin K, vitamin D and bone metabolism.…”

Vitamin D and K status influences bone mineral density and bone accrual in children and adolescents with celiac disease

“…In those at risk, vitamin K deficiency increases fracture risk, while supplementation is protective (Cockayne et al, 2006). There is increasing evidence that vitamin K has positive effects on calcium metabolism both independent and synergistic with vitamin D and this may be very relevant for the inadequately explained and persistent abnormalities in calcium metabolism observed in CD (Koshihara et al, 1996;Kobayashi et al, 2002).…”