Gene expression profiles in rat intestine identify pathways for 1,25-dihydroxyvitamin D3 stimulated calcium absorption and clarify its immunomodulatory properties

Abstract

Microarray technology has been used to discover 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) induced gene expression changes in rat small intestine in vivo. Here, we report gene expression changes related to intestinal absorption or transport, the immune system and angiogenesis in response to 1,25-(OH)(2)D(3). Vitamin D deficient rats were intrajugularly given vehicle or vehicle containing 730 ng of 1,25-(OH)(2)D(3)/kg of body weight. Intestinal mRNA was harvested from duodenal mucosa at 15 min, 1, 3, and 6 h post-injection and studied by Affymetrix microarrays. Genes significantly affected by 1,25-(OH)(2)D(3) were confirmed by quantitative RT-PCR with remarkable agreement. The most strongly affected gene in intestine was CYP24 with 97-fold increase at 6 h post-1,25-(OH)(2)D(3) treatment. Intestinal calcium absorption genes: TRPV5, TRPV6, calbindin D(9k), and Ca(2+) dependent ATPase all were up-regulated in response to 1,25-(OH)(2)D(3), supporting the currently accepted mechanism of 1,25-(OH)(2)D(3) induced transcellular calcium transport. However, a 1,25-(OH)(2)D(3) suppression of several intra-/intercellular matrix modeling proteins such as sodium/potassium ATPase, claudin 3, aquaporin 8, cadherin 17, and RhoA suggests a vitamin D regulation of tight junction permeability and paracellular calcium transport. Several other genes related to the immune system and angiogenesis whose expression was changed in response to 1,25-(OH)(2)D(3) provided evidence for an immunomodulatory and anti-angiogenic role of 1,25-(OH)(2)D(3).

Tight Junction Proteins Claudin-2 and -12 Are Critical for Vitamin D-dependent Ca2+ Absorption between Enterocytes

“…The lack of VDR transcripts and proteins in the intestine of VDRKO mice was confirmed by RT-PCR and immunoblot experiments ( Figures 1A and 2, A and C; data not shown). As shown in Figure 1, A and B, expression levels of Cldn3 transcripts were higher in the jejunum in VDRKO mice than in WT mice, in good agreement with the finding that the gene expression of Cldn3 is decreased in the rat small intestine after 1␣,25(OH) 2 D 3 treatment (Kutuzova and Deluca, 2004). In contrast, the mRNA expression of Cldn2 and Cldn12, but not Cldn7 or Cldn15, was reduced in the VDRKO mouse jejunum compared with that of the WT mouse (ϳ3-and 4-fold decreases, respectively).…”

TRPV6 is not required for 1α,25-dihydroxyvitamin D 3 -induced intestinal calcium absorption in vivo

“…We and others suggested the involvement of vitamin D in the regulation of paracellular calcium transport in the intestine (6,7,19,20). From a microarray study in rats, it seemed likely that vitamin D regulates tight junction permeability in intestine by regulating expression of several tight junction proteins including claudin-3 (6).…”

“…Because this hormonal form of vitamin D is regulated in response to the need for calcium, it became clear that the endogenous factor discovered by Nicolaysen and Egg-Larsen is the vitamin D endocrine system producing the final vitamin D hormone, 1,25-(OH) 2 D 3 (4,5). There is still debate whether vitamin D further influences the diffusional component of calcium absorption, taking place at high intestinal levels of calcium (6,7).…”

“…The hybridization reaction and the automated hybridization procedure to Affymetrix Rat Expression Arrays 230 2.0 were performed by the Gene Expression Center at the Biotechnology Center of the University of Wisconsin-Madison as described (6,26). Each probe sample was tested on an Affymetrix Test3 Array and the quality of the cDNA and cRNA syntheses was determined by the 3Ј/5Ј ratio of housekeeping genes within the array (ubiquitin, rat glyceraldehyde 3-phosphate dehydrogenase, ␤-actin, and hexokinase).…”

Modulation of the Intestinal Ca2+Uptake by a Cheese Whey Protein Digest

“…The expression of calbindin-D is induced by dihydroxycholescalciferol (1,25-(OH) 2 D 3 ). 6) Low luminal calcium up-regulates the active transport by increasing the CaT1 and ECaC1 mRNA. 7,8) Researchers have also found that the intestinal calcium absorption can be enhanced by various food factors.…”