In Vitro Non-Genomic Effects of Calcifediol on Human Preosteoblastic Cells.

Simone Donati,Gemma Marcucci,Teresa Iantomasi,Cinzia Aurilia,Maria Luisa Brandi,Gaia Palmini,Roberto Zonefrati,Francesca Marini,Francesca Miglietta,Cecilia Romagnoli,Irene Falsetti,Gianna Galli

doi:10.3390/nu13124227

Abstract

Several recent studies have demonstrated that the direct precursor of vitamin D3, the calcifediol [25(OH)D3], through the binding to the nuclear vitamin D receptor (VDR), is able to regulate the expression of many genes involved in several cellular processes. Considering that itself may function as a VDR ligand, although with a lower affinity, respect than the active form of vitamin D, we have assumed that 25(OH)D3 by binding the VDR could have a vitamin’s D3 activity such as activating non-genomic pathways, and in particular we selected mesenchymal stem cells derived from human adipose tissue (hADMSCs) for the in vitro assessment of the intracellular Ca2+ mobilization in response to 25(OH)D3. Our result reveals the ability of 25(OH)D3 to activate rapid, non-genomic pathways, such as an increase of intracellular Ca2+ levels, similar to what observed with the biologically active form of vitamin D3. hADMSCs loaded with Fluo-4 AM exhibited a rapid and sustained increase in intracellular Ca2+ concentration as a result of exposure to 10−5 M of 25(OH)D3. In this work, we show for the first time the in vitro ability of 25(OH)D3 to induce a rapid increase of intracellular Ca2+ levels in hADMSCs. These findings represent an important step to better understand the non-genomic effects of vitamin D3 and its role in endocrine system.

Highlights

Its actions are mediated via the interaction with the nuclear vitamin D receptor (VDR), to promote the expression of genes related to bone remodelling, such as alkaline phosphatase (ALP), type I collagen, and non-collagenous proteins [2,3,4]
To assess in vitro the capacity of 25(OH)D3 to trigger rapid non-genomic respon we evaluated its effects on the mobilization of intracellular Ca2+ levels in hADMSC
3, the biologically active form of vitamin D, has been showed classically to mediate its effects biologically active form of vitamin D, has been showed classically to mediate its effects through the interaction with a VDR, a nuclear receptor found to be expressed in virtually all cell types [1,3]

Summary

Introduction

Calcitriol (1α,25-(OH) D3 ), the biologically active form of vitamin D3 , is a hormone that participates in many biological processes, including the regulation of the serum calcium and phosphate levels, in addition to exerting direct effects on bone and mineral metabolism [1]. Its actions are mediated via the interaction with the nuclear vitamin D receptor (VDR), to promote the expression of genes related to bone remodelling, such as alkaline phosphatase (ALP), type I collagen, and non-collagenous proteins [2,3,4]. Either positively or negatively regulating the expression of target genes by binding to their promoter regions through vitamin D3 response elements (VDREs) [2]. In addition to genomic actions, all the steroid molecules have been proven to transmit via specific membrane receptors rapid non-genomic effects [5].

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Results

Conclusion