Expression of calbindin-D9k, VDR and Cdx-2 messenger RNA in the process by which fructooligosaccharides increase calcium absorption in rats.
We have previously shown, through evidence that the expression of calbindin-D9k protein shows a dose-dependent change in the intestine, that calbindin-D9k plays a role in the ability of a fructooligosaccharide (FOS) diet to increase calcium absorption. This study shows that the regulation of calbindin-D9k expression occurs at the transcriptional level in a segment-specific manner, decreasing in the proximal intestine and increasing in the colorectal segment. To determine the transcriptional regulation of the FOS diet on calbindin-D9k expression, two transcription factors, vitamin D receptor (VDR) and cdx-2, were analyzed during 10 d feeding of the FOS diet. The mRNA expression of VDR and cdx-2 was influenced by the FOS diet and showed a segment-specific change. In the proximal small intestine, there was a significant correlation between the changes in both mRNAs (r = 0.69, p < 0.01), while the expression of calbindin-D9k correlated neither with VDR nor with cdx-2. This means that the transcriptional change induced by the FOS diet was not regulated by VDR and cdx-2. In the colorectal segment, there were significant correlations between gene expressions of calbindin-D9k vs. VDR, r = 0.73, p < 0.01 and calbindin-D9k vs. cdx-2, r = 0.52, p < 0.05. These results suggested that both transcription factors, VDR and cdx-2, were involved in the regulation of calbindin-D9k gene expression in the colorectal segment during the process through which the FOS diet enhanced calcium absorption.
Fukushima
Akiko
A
Department of Molecular Nutrition, Kagawa Nutrition University, 3-9-21 Chiyoda, Sakado, Saitama 350-0288, Japan.
Ohta
Atsutane
A
Sakai
Kensuke
K
Sakuma
Keiko
K
D000818:Animals; D015152:Blotting, Northern; D000071616:CDX2 Transcription Factor; D064026:Calbindins; D002118:Calcium / Q000493:pharmacokinetics*; D004247:DNA / Q000032:analysis; D004032:Diet; D005786:Gene Expression Regulation / Q000187:drug effects; D018398:Homeodomain Proteins / Q000235:genetics*; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000033:anatomy & histology / Q000737:chemistry; D008297:Male; D009844:Oligosaccharides / Q000008:administration & dosage*; D009929:Organ Size / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018167:Receptors, Calcitriol / Q000235:genetics*; D064030:S100 Calcium Binding Protein G / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics*
D000071616:CDX2 Transcription Factor; D064026:Calbindins; D018398:Homeodomain Proteins; D009844:Oligosaccharides; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D064030:S100 Calcium Binding Protein G; C576508:S100g protein, rat; D015534:Trans-Activators; C116580:fructooligosaccharide; D004247:DNA; D002118:Calcium