title: 1,25-Dihydroxyvitamin D3 upregulates natriuretic peptide receptor-C expression in mouse osteoblasts.
abstract: 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], a key regulator of mineral metabolism, regulates expression of several genes related to bone formation. The present study examined the 1,25(OH)2D3-mediated regulation of natriuretic peptide receptor-C (NPR-C) expression in osteoblasts. 1,25(OH)2D3 treatment significantly increased NPR-C-dependent atrial natriuretic peptide-binding activity and synthesis of the NPR-C protein in mouse osteoblastic cells in a cell-specific manner. Western blot analysis also demonstrated that 1, 25(OH)2D3 upregulated expression of NPR-C protein in slow kinetics. Next, Northern blot analysis revealed a significant increase in the steady-state NPR-C mRNA level by 1,25(OH)2D3. Sequence analysis of the 9 kb of the 5'-flanking region of the mouse NPR-C gene revealed an absence of consensus vitamin D-response elements, and promoter analysis using osteoblastic cells stably transfected with mouse NPR-C promoter-reporter constructs showed a slight increase of promoter activity with 1,25(OH)2D3 treatment. In addition, a nuclear run-on assay exhibited that the transcriptional rate of the NPR-C gene was unchanged by 1,25(OH)2D3, whereas that of the osteopontin gene was increased. Evaluation of NPR-C mRNA half-life demonstrated that 1,25(OH)2D3 significantly increased the NPR-C mRNA stability in osteoblastic cells. 1,25(OH)2D3 attenuated intracellular cGMP production in osteoblastic cells stimulated by C-type natriuretic peptide (CNP) without a significant change of the natriuretic peptide receptor-B mRNA level, suggesting enhancement of the clearance of exogenously added CNP via NPR-C. Furthermore, NPR-C and osteopontin mRNAs in mouse calvariae were significantly increased by administration of 1,25(OH)2D3, and immunohistological analysis demonstrated that NPR-C is actually and strongly expressed in mouse periosteal fibroblasts. These findings suggest that 1,25(OH)2D3 can play a critical role for determination of the natriuretic peptide availability in bones by regulation of NPR-C expression through stabilizing its mRNA.
authors.affiliation: Discovery Research Laboratory, Tanabe Seiyaku, Osaka 532-8505, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yanaka
authors.forename: H
authors.initials: H
authors.lastname: Akatsuka
authors.forename: E
authors.initials: E
authors.lastname: Kawai
authors.forename: K
authors.initials: K
authors.lastname: Omori
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002478:Cells, Cultured; D006162:Guanylate Cyclase / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D020098:Natriuretic Peptide, C-Type / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017461:Receptors, Atrial Natriuretic Factor / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; D020098:Natriuretic Peptide, C-Type; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C; D002117:Calcitriol