Parathyroid hormone stimulation of the renal 25-hydroxyvitamin D-1α-hydroxylase—Effect of age and free radicals

Armbrecht, H. J.; Boltz, M. A.; Ritter, Cynthia S.; Brown, Alex

doi:10.1016/j.jsbmb.2006.12.035

Cited by 13 publications

(8 citation statements)

References 12 publications

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“…Considering the increased total urinary Ca excretion concomitant with elevated serum PTH levels, reabsorption function might become desensitization in response to elevated PTH levels in aged rats. Indeed, similar observations have been reported that the capacity of PTH to increase serum levels of 1,25-dihydroxyvitamin D [1,25(OH) 2 D] declines with age in both rats and humans (Ambrecht et al, 2007). In addition, elevated PTH levels in aged rats might be caused by increased urinary Ca excretion to maintain constantly serum Ca levels through facilitation of Ca mobilization from the bone.…”

Section: Discussionsupporting

confidence: 62%

Hachimijiogan (Ba-Wei-Di-Huang-Wan), a herbal medicine, improves unbalance of calcium metabolism in aged rats

Ikeda

Mizoguchi

2009

Journal of Ethnopharmacology

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Section: Discussionsupporting

confidence: 62%

Hachimijiogan (Ba-Wei-Di-Huang-Wan), a herbal medicine, improves unbalance of calcium metabolism in aged rats

Ikeda

Mizoguchi

2009

Journal of Ethnopharmacology

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“…This is unexpected since the efficiency of the photosynthesis of vitamin D in human skin decreases with age [32]. Nevertheless, other factors may explain this discrepancy: food habits and awareness of the possibility of vitamin D deficiency may be different for different age groups, and there may be a low activity of the renal 1-alfa hydroxylase or a lower stimulatory effect of PTH on this enzyme in old than in young persons [33].…”

Section: Discussionmentioning

confidence: 99%

Seasonal variation of 1,25-dihydroxyvitamin D and its association with body mass index and age

Moan¹,

Lagunova

Lindberg³

et al. 2009

The Journal of Steroid Biochemistry and Molecular Biology

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“…Equal protein loading was determined using a mouse anti-ERK 2 monoclonal antibody (Santa Cruz Biotechnology, Inc., Santa Cruz, CA). For detection of 1α-hydroxylase protein, membranes were probed with rabbit anti-1α-hydroxylase polyclonal antibody (1∶1500 dilution) [51]. Equal protein loading was determined using a rabbit anti-β-actin polyclonal antibody (1∶6500) (Cell Signaling Technology, Danvers, MA).…”

Section: Methodsmentioning

confidence: 99%

FGF-23 Regulates CYP27B1 Transcription in the Kidney and in Extra-Renal Tissues

et al. 2013

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The mitochondrial enzyme 25-hydroxyvitamin D 1α-hydroxylase, which is encoded by the CYP27B1 gene, converts 25OHD to the biological active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D). Renal 1α-hydroxylase activity is the principal determinant of the circulating 1,25(OH)2D concentration and enzyme activity is tightly regulated by several factors. Fibroblast growth factor-23 (FGF-23) decreases serum 1,25(OH)2D concentrations by suppressing CYP27B1 mRNA abundance in mice. In extra-renal tissues, 1α-hydroxylase is responsible for local 1,25(OH)2D synthesis, which has important paracrine actions, but whether FGF-23 regulates CYP27B1 gene expression in extra-renal tissues is unknown. We sought to determine whether FGF-23 regulates CYP27B1 transcription in the kidney and whether extra-renal tissues are target sites for FGF-23-induced suppression of CYP27B1. In HEK293 cells transfected with the human CYP27B1 promoter, FGF-23 suppressed promoter activity by 70%, and the suppressive effect was blocked by CI-1040, a specific inhibitor of extracellular signal regulated kinase 1/2. To examine CYP27B1 transcriptional activity in vivo, we crossed fgf-23 null mice with mice bearing the CYP27B1 promoter-driven luciferase transgene (1α-Luc). In the kidney of FGF-23 null/1α-Luc mice, CYP27B1 promoter activity was increased by 3-fold compared to that in wild-type/1α-Luc mice. Intraperitoneal injection of FGF-23 suppressed renal CYP27B1 promoter activity and protein expression by 26% and 60% respectively, and the suppressive effect was blocked by PD0325901, an ERK1/2 inhibitor. These findings provide evidence that FGF-23 suppresses CYP27B1 transcription in the kidney. Furthermore, we demonstrate that in FGF-23 null/1α-Luc mice, CYP27B1 promoter activity and mRNA abundance are increased in several extra-renal sites. In the heart of FGF-23 null/1α-Luc mice, CYP27B1 promoter activity and mRNA were 2- and 5-fold higher, respectively, than in control mice. We also observed a 3- to 10-fold increase in CYP27B1 mRNA abundance in the lung, spleen, aorta and testis of FGF-23 null/1α-Luc mice. Thus, we have identified novel extra-renal target sites for FGF-23-mediated regulation of CYP27B1.

show abstract

Parathyroid hormone stimulation of the renal 25-hydroxyvitamin D-1α-hydroxylase—Effect of age and free radicals

Cited by 13 publications

References 12 publications

Hachimijiogan (Ba-Wei-Di-Huang-Wan), a herbal medicine, improves unbalance of calcium metabolism in aged rats

Hachimijiogan (Ba-Wei-Di-Huang-Wan), a herbal medicine, improves unbalance of calcium metabolism in aged rats

Seasonal variation of 1,25-dihydroxyvitamin D and its association with body mass index and age

FGF-23 Regulates CYP27B1 Transcription in the Kidney and in Extra-Renal Tissues

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