Vitamin D plays an important role in preserving healthy bones, and has additional roles in the body, including modulation of cell growth, differentiation, neuromuscular and immune function, and anti-inflammatory function. The vitamin D receptor (VDR) is a member of the nuclear hormone receptor superfamily and regulates transcription of vitamin D-dependent target genes, such as those for key proteins involved in calcium and phosphorus absorption and bone development. Histone acetylation weakens the association of histones with DNA, and increases the accessibility of transcriptional regulatory proteins to chromatin templates, thereby increasing transcriptional activity of gene expression. Histone deacetylases remove the acetyl groups and condense chromatin structure, thereby preventing transcription. TSA is a potent histone deacetylase inhibitor and can significantly enhance gene expression. Bioactive food component, sulforaphane (SFN) is found in cruciferous vegetables and is known to be a histone deacetylase inhibitor, leading to transcriptional activation of gene expression. The objective of this study is to demonstrate that the bioactive food components modulate vitamin D action in adipocytes. To investigate the effects of TSA and SFN on vitamin D response, 3T3L1 mouse preadipocytes were treated with the combination of various concentrations of 1,25(OH)2 vitamin D, TSA, and SFN. Upon harvesting cells, the amounts of 24-hydroxylase mRNA, marker of vitamin D response, were measured by semiquantitative reverse transcriptase-PCR analysis. The results showed that the cells treated with 1μM TSA increased 1,25(OH)2 vitamin D-induced CYP24 mRNA level nearly 3.5-fold (p < 0.05) at 1nM 1,25(OH)2 vitamin D and nearly 2.5-fold (p < 0.05) in 10 nM 1,25(OH)2 vitamin D, and the cells treated with 5μM SFN increased 1,25(OH)2 vitamin D-induced CYP24 mRNA level nearly 1.4-fold at 1nM 1,25(OH)2 vitamin D and nearly 1.2-fold at 10 nM 1,25(OH)2 vitamin D.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal