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Differential role of two VDR coactivators, DRIP205 and SRC-3, in keratinocyte proliferation and differentiation 总被引:3,自引:0,他引:3
Oda Y Ishikawa MH Hawker NP Yun QC Bikle DD 《The Journal of steroid biochemistry and molecular biology》2007,103(3-5):776-780
Cell programs such as proliferation and differentiation involve the selective activation and repression of gene expression. The vitamin D receptor (VDR), through 1,25(OH)(2)D(3), controls the proliferation and differentiation of keratinocytes. Previously, we have identified two VDR binding coactivator complexes. In proliferating keratinocytes VDR bound preferentially to the DRIP complex, whereas in differentiated keratinocytes the SRC complex was preferred. We proposed that different coactivators are required for sequential gene regulation in the transition from proliferation to differentiation. Here we examined the roles of DRIP205 and SRC-3 in this transition. Silencing of DRIP205 and VDR caused hyperproliferation of keratinocytes, demonstrated by increased XTT and BrdU incorporation. SRC-3 silencing, on the other hand, did not have an effect on proliferation. In contrast, SRC-3 as well as DRIP205 and VDR silencing blocked keratinocyte differentiation as shown by decreased expression of keratin 1 and filaggrin. These results are consistent with the differential localization of DRIP205 and SRC-3 in skin. These results indicate that DRIP205 is required for keratinocyte proliferation. Both DRIP205 and SRC-3 are required for the keratinocyte differentiation. These results support the concept that the selective use of coactivators by VDR underlies the selective regulation of gene expression in keratinocyte proliferation and differentiation. 相似文献
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1,25 Dihydroxyvitamin D (1,25(OH)(2)D) regulates the differentiation of keratinocytes. 1,25(OH)(2)D raises intracellular free calcium (Cai) as a necessary early step toward stimulating differentiation. 1,25(OH)(2)D induces the calcium sensing receptor (CaR) in keratinocytes and enhances the calcium response of these cells. Activation of the CaR by calcium increases intracellular free calcium by a mechanism involving phospholipase C (PLC) cleavage of phosphatidylinositolbisphosphate into inositoltrisphosphate (IP(3)) and diacylglycerol (DG). 1,25(OH)(2)D induces the family of PLCs. PLC-gamma1 has a DR6 VDRE in its promoter which binds and is activated by VDR/RAR rather than VDR/RXR. The involucrin gene, which encodes a critical component of the cornified envelope, contains a DR3 VDRE in its promoter that acts in conjunction with a nearby AP-1 site. The sequential regulation of these genes is critical for the differentiation process. In undifferentiated keratinocytes, the VDR binds preferentially to the DRIP complex of coactivators. However, with differentiation DRIP 205 is no longer produced, and the VDR switches partners to the SRC family (SRC2 and 3). These studies suggest that at least part of the sequential activation of genes required during keratinocyte differentiation is regulated by the change (availability) of these different coactivator complexes. 相似文献
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Prema B. Rapuri J.C. Gallagher Zafar Nawaz 《The Journal of steroid biochemistry and molecular biology》2007,103(3-5):368
Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)2D3, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)2D3 mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)2D3 induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)2D3 induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)2D3 induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50–70%, respectively. In addition, the 1,25(OH)2D3 induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)2D3 stimulated VDR protein expression and 1,25(OH)2D3 mediated actions in human osteoblast cells. 相似文献
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WEHI-3B D− cells differentiate in response to 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) but not to all-trans-retinoic acid (RA) or other inducing agents. Combinations of RA with 1,25-(OH)2D3 interact to produce synergistic differentiation of WEHI-3B D− cells. To determine factors involved in the synergistic interaction, expression of the 1,25-(OH)2D3 receptor (VDR) and retinoid receptors, RARα and RXRα, was measured. No VDR was detected in untreated WEHI-3B D− cells; however, RA and 1,25-(OH)2D3 when used as single agents caused a slight induction of the VDR and in combination produced a marked increase in the VDR. In contrast, no changes in RARα and RXRα were initiated by these compounds. An RAR-selective agonist combined with 1,25-(OH)2D3 produced synergistic differentiation of WEHI-3B D− cells, whereas an RXR-selective agonist did not. To gain information on the role of the VDR in the synergistic interaction, the VDR gene was transferred into WEHI-3B D+ cells, in which no VDR was detected and no synergism was produced. Expression of the VDR conferred differentiation responsiveness to 1,25-(OH)2D3 in WEHI-3B D+ cells. These findings suggest that (a) induction of VDR expression is a key component in the synergistic differentiation induced by 1,25-(OH)2D3 and RA and (b) RAR and not RXR must be activated for enhanced induction of the VDR and for the synergistic differentiation produced by RA and 1,25-(OH)2D3. 相似文献
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Susumi Hatakeyama Satoshi Nagashima Naoko Imai Keisuke Takahashi Jun Ishihara Atsuko Sugita Takeshi Nihei Hitoshi Saito Fumiaki Takahashi Noboru Kubodera 《The Journal of steroid biochemistry and molecular biology》2007,103(3-5):222
1α,25-Dihydroxy-2β-(3-hydroxypropoxy)vitamin D3 (ED-71), an analog of active vitamin D3, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], possesses a hydroxypropoxy substituent at the 2β-position of 1,25(OH)2D3. ED-71 has potent biological effects on bone and is currently under phase III clinical studies for bone fracture prevention. It is well-known that the synthesis and secretion of parathyroid hormone (PTH) is regulated by 1,25(OH)2D3. Interestingly, during clinical development of ED-71, serum intact PTH in osteoporotic patients did not change significantly upon treatment with ED-71. The reason remains unclear, however. Brown et al. reported that 3-epi-1,25(OH)2D3, an epimer of 1,25(OH)2D3 at the 3-position, shows equipotent and prolonged activity compared to 1,25(OH)2D3 at suppressing PTH secretion. Since ED-71 has a bulky hydroxypropoxy substituent at the 2-position, epimerization at the adjacent and sterically hindered 3-position might be prevented, which may account for its weak potency in PTH suppression observed in clinical studies. We have significant interest in ED-71 epimerization at the 3-position and the biological potency of 3-epi-ED-71 in suppressing PTH secretion. In the present studies, synthesis of 3-epi-ED-71 and investigations of in vitro suppression of PTH using bovine parathyroid cells are described. The inhibitory potency of vitamin D3 analogs were found to be 1,25(OH)2D3 > ED-71 ≥ 3-epi-1,25(OH)2D3 3-epi-ED-71. ED-71 and 3-epi-ED-71 showed weak activity towards PTH suppression in our assays. 相似文献
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Identification of novel mediators of Vitamin D signaling and 1,25(OH)2D3 resistance in mammary cells
Belinda Byrne JoEllen Welsh 《The Journal of steroid biochemistry and molecular biology》2007,103(3-5):703
Since the discovery of the Vitamin D receptor (VDR) in mammary cells, the role of the Vitamin D signaling pathway in normal glandular function and in breast cancer has been extensively explored. In vitro studies have demonstrated that the VDR ligand, 1,25(OH)2D3, modulates key proteins involved in signaling proliferation, differentiation and survival of normal mammary epithelial cells. Anti-proliferative and pro-differentiating effects of 1,25(OH)2D3 have also been observed in VDR positive breast cancer cells, indicating that transformation per se does not abolish Vitamin D signaling. However, many breast cancer cell lines are less sensitive to 1,25(OH)2D3 than normal mammary epithelial cells. Reduced sensitivity to 1,25(OH)2D3 has been linked to alterations in Vitamin D metabolizing enzymes as well as down regulation of VDR expression or function. In this report, we describe results from a proteomics screening approach used to search for proteins involved in dictating sensitivity or resistance to Vitamin D mediated apoptosis in breast cancer cells. Several proteins not previously linked to 1,25(OH)2D3 signaling were identified with this approach, and a distinct subset of proteins was linked to 1,25(OH)2D3 resistance. Follow-up studies to determine the relevance of these proteins to Vitamin D signaling in general are in progress. 相似文献
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The Paracrine Feedback Loop Between Vitamin D3 (1,25(OH)2D3) and PTHrP in Prehypertrophic Chondrocytes
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Frances C. Bach Kirsten Rutten Kristyanne Hendriks Frank M. Riemers Peter Cornelissen Alain de Bruin Ger J. Arkesteijn Richard Wubbolts William A. Horton Louis C. Penning Marianna A. Tryfonidou 《Journal of cellular physiology》2014,229(12):1999-2014
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Both calcium and 1,25(OH)(2)D promote the differentiation of keratinocytes in vitro. The autocrine or paracrine production of 1,25(OH)(2)D by keratinocytes combined with the critical role of the epidermal calcium gradient in regulating keratinocyte differentiation in vivo suggest the physiologic importance of this interaction. The interactions occur at a number of levels. Calcium and 1,25(OH)(2)D synergistically induce involucrin, a protein critical for cornified envelope formation. The involucrin promoter contains an AP-1 site essential for calcium and 1,25(OH)(2)D induction and an adjacent VDRE essential for 1,25(OH)(2)D but not calcium induction. Calcium regulates coactivator complexes that bind to the Vitamin D receptor (VDR). Nuclear extracts from cells grown in low calcium contain an abundance of DRIP(205), whereas calcium induced differentiation leads to reduced DRIP(205) and increased SRC 3 which replaces DRIP in its binding to the VDR. In vivo models support the importance of 1,25(OH)(2)D-calcium interactions in epidermal differentiation. The epidermis of 1alphaOHase null mice fails to form a normal calcium gradient, has reduced expression of proteins critical for barrier function, and shows little recovery of the permeability barrier when disrupted. Thus in vivo and in vitro, calcium and 1,25(OH)(2)D interact at multiple levels to regulate epidermal differentiation. 相似文献