Prednisolone-induced Ca2+ malabsorption is caused by diminished expression of the epithelial Ca2+ channel TRPV6

2007 ◽  
Vol 292 (1) ◽  
pp. G92-G97 ◽  
Author(s):  
Sylvie Huybers ◽  
Ton H. J. Naber ◽  
René J. M. Bindels ◽  
Joost G. J. Hoenderop
Keyword(s):  
Absorption Capacity ◽  
Mrna Levels ◽  
Plasma Membrane Atpase ◽  
Mineral Density ◽  
Dihydroxyvitamin D ◽  
Prednisolone Treatment ◽  
Expression Studies ◽  
Calbindin D ◽  
Reduce Bone Mineral Density

Glucocorticoids, such as prednisolone, are often used in clinic because of their anti-inflammatory and immunosuppressive properties. However, glucocorticoids reduce bone mineral density (BMD) as a side effect. Malabsorption of Ca2+ in the intestine is supposed to play an important role in the etiology of low BMD. To elucidate the mechanism of glucocorticoid-induced Ca2+ malabsorption, the present study investigated the effect of prednisolone on the expression and activity of proteins responsible for active intestinal Ca2+ absorption including the epithelial Ca2+ channel TRPV6, calbindin-D9K, and the plasma membrane ATPase PMCA1b. Therefore, C57BL/6 mice received 10 mg/kg body wt prednisolone daily by oral gavage for 7 days and were compared with control mice receiving vehicle only. An in vivo 45Ca2+ absorption assay indicated that intestinal Ca2+ absorption was diminished after prednisolone treatment. We showed decreased duodenal TRPV6 and calbindin-D9K mRNA and protein abundance in prednisolone-treated compared with control mice, whereas PMCA1b mRNA levels were not altered. Importantly, detailed expression studies demonstrated that in mice these Ca2+ transport proteins are predominantly localized in the first 2 cm of the duodenum. Furthermore, serum Ca2+ and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] concentrations remained unchanged by prednisolone treatment. In conclusion, these data suggest that prednisolone reduces the intestinal Ca2+ absorption capacity through diminished duodenal expression of the active Ca2+ transporters TRPV6 and calbindin-D9K independent of systemic 1,25(OH)2D3.

Regulation of the epithelial Ca2+ channels in small intestine as studied by quantitative mRNA detection

2003 ◽  
Vol 285 (1) ◽  
pp. G78-G85 ◽  
Author(s):  
Monique van Abel ◽  
Joost G. J. Hoenderop ◽  
Annemiete W. C. M. van der Kemp ◽  
Johannes P. T. M. van Leeuwen ◽  
René J. M. Bindels
Keyword(s):  
Knockout Mice ◽  
Hormonal Regulation ◽  
Transport Proteins ◽  
Ovariectomized Rats ◽  
Mrna Levels ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Genes Encoding ◽  
Calbindin D

The epithelial Ca2+ channels TRPV5 and TRPV6 are localized to the brush border membrane of intestinal cells and constitute the postulated rate-limiting entry step of active Ca2+ absorption. The aim of the present study was to investigate the hormonal regulation of these channels. To this end, the effect of 17β-estradiol (17β-E2), 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and dietary Ca2+ on the expression of the duodenal Ca2+ transport proteins was investigated in vivo and analyzed using realtime quantitative PCR. Supplementation with 17β-E2 increased duodenal gene expression of TRPV5 and TRPV6 but also calbindin-D9K and plasma membrane Ca2+-ATPase (PMCA1b) in ovariectomized rats. 25-Hydroxyvitamin D3-1α-hydroxylase (1α-OHase) knockout mice are characterized by hyperparathyroidism, rickets, hypocalcemia, and undetectable levels of 1,25(OH)2D3 and were used to study the 1,25(OH)2D3-dependency of the stimulatory effects of 17β-E2. Treatment with 17β-E2 upregulated mRNA levels of duodenal TRPV6 in these 1α-OHase knockout mice, which was accompanied by increased serum Ca2+ concentrations from 1.69 ± 0.10 to 2.03 ± 0.12 mM ( P < 0.05). In addition, high dietary Ca2+ intake normalized serum Ca2+ in these mice and upregulated expression of genes encoding the duodenal Ca2+ transport proteins except for PMCA1b. Supplementation with 1,25(OH)2D3 resulted in increased expression of TRPV6, calbindin-D9K, and PMCA1b and normalization of serum Ca2+. Expression levels of duodenal TRPV5 mRNA are below detection limits in these 1α-OHase knockout mice, but supplementation with 1,25(OH)2D3 upregulated the expression to significant levels. In conclusion, TRPV5 and TRPV6 are regulated by 17β-E2 and 1,25(OH)2D3, whereas dietary Ca2+ is positively involved in the regulation of TRPV6 only.

1,25(OH)2D3 acts as a bone-forming agent in the hormone-independent senescence-accelerated mouse (SAM-P/6)

2005 ◽  
Vol 288 (4) ◽  
pp. E723-E730 ◽  
Author(s):  
Gustavo Duque ◽  
Michael Macoritto ◽  
Natalie Dion ◽  
Louis-Georges Ste-Marie ◽  
Richard Kremer
Keyword(s):  
Bone Formation ◽  
Bone Turnover ◽  
Bone Marrow Cells ◽  
Formation Rate ◽  
Mineral Density ◽  
Bone Formation Rate ◽  
Senile Osteoporosis ◽  
Dihydroxyvitamin D ◽  
Bone Formation Markers

Recent studies suggest that vitamin D signaling regulates bone formation. However, the overall effect of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on bone turnover in vivo is still unclear. In this study, our aim was to examine the effect of 1,25(OH)2D3 on bone turnover in SAM-P/6, a hormone-independent mouse model of senile osteoporosis characterized by a decrease in bone formation. Male and female 4-mo-old SAM-P/6 mice were treated with 1,25(OH)2D3 (18 pmol/24 h) or vehicle for a period of 6 wk, and a group of age- and sex-matched nonosteoporotic animals was used as control. Bone mineral density (BMD) at the lumbar spine increased rapidly by >30 ± 5% ( P < 0.001) in 1,25(OH)2D3-treated SAM-P/6 animals, whereas BMD decreased significantly by 18 ± 2% ( P < 0.01) in vehicle-treated SAM-P/6 animals and remained stable in control animals during the same period. Static and dynamic bone histomorphometry indicated that 1,25(OH)2D3 significantly increased bone volume and other parameters of bone quality as well as subperiosteal bone formation rate compared with vehicle-treated SAM-P/6 mice. However, no effect on trabecular bone formation was observed. This was accompanied by a marked decrease in the number of osteoclasts and eroded surfaces. A significant increase in circulating bone formation markers and a decrease in bone resorption markers was also observed. Finally, bone marrow cells, obtained from 1,25(OH)2D3-treated animals and cultured in the absence of 1,25(OH)2D3, differentiated more intensely into osteoblasts compared with those derived from vehicle-treated mice cultured in the same conditions. Taken together, these findings demonstrate that 1,25(OH)2D3 acts simultaneously on bone formation and resorption to prevent the development of senile osteoporosis.

scholarly journals Misexpression of CCAAT/enhancer binding protein beta causes osteopenia

2009 ◽  
Vol 201 (2) ◽  
pp. 263-274 ◽  
Author(s):  
Stefano Zanotti ◽  
Lisa Stadmeyer ◽  
Anna Smerdel-Ramoya ◽  
Deena Durant ◽  
Ernesto Canalis
Keyword(s):  
Alkaline Phosphatase ◽  
Leukemia Virus ◽  
Bone Volume ◽  
Mrna Levels ◽  
Wild Type ◽  
Mineral Density ◽  
Wild Type Littermate ◽  
Transgenic Lines ◽  
Trabecular Number

CCAAT/enhancer binding proteins (C/EBPs) are expressed by osteoblasts and adipocytes during differentiation. C/EBPβ is critical for adipogenesis; however, its role in osteoblastogenesis is unclear, and its function in the postnatal skeleton is not known. To study C/EBPβ in osteoblasts in vivo, we created transgenic mice expressing full length C/EBPβ under the control of a 3.8 kb fragment of the human osteocalcin promoter. Two transgenic lines were established in a friend leukemia virus strain B genetic background, and compared with wild type littermate controls. Both C/EBPβ transgenic lines exhibited osteopenia, with a 30% decrease in bone volume, due to a decrease in trabecular number. The number of osteoblasts and osteoclasts per bone perimeter was not changed. Bone marrow stromal cells from C/EBPβ transgenics showed reduced mineralization, and reduced alkaline phosphatase mRNA levels. Calvarial osteoblasts from C/EBPβ transgenics displayed reduced alkaline phosphatase activity. To determine the consequences of the Cebpb deletion in vivo, the phenotype of Cebpb null mice was compared with that of wild type controls of identical genetic composition. Cebpb null mice exhibited reduced weight, body fat, and bone mineral density, and decreased bone volume, due to a decrease in trabecular number. The number of osteoblasts and osteoclasts per bone perimeter was not changed. C/EBPβ downregulation by RNA interference in calvarial osteoblasts had no effect on osteoblast differentiation/function. The phenotype of the Cebpb inactivation may be secondary to systemic indirect effects, and to direct effects of C/EBPβ in osteoblasts. In conclusion, C/EBPβ plays a role in mesenchymal cell differentiation and its misexpression in vivo causes osteopenia.

scholarly journals The epithelial sodium/proton exchanger, NHE3, is necessary for renal and intestinal calcium (re)absorption

2012 ◽  
Vol 302 (8) ◽  
pp. F943-F956 ◽  
Author(s):  
Wanling Pan ◽  
Jelena Borovac ◽  
Zachary Spicer ◽  
Joost G. Hoenderop ◽  
René J. Bindels ◽  
...  
Keyword(s):  
Bone Mineralization ◽  
Fractional Excretion ◽  
Osmotic Gradient ◽  
Wild Type ◽  
Mineral Density ◽  
Ussing Chambers ◽  
Sodium Proton Exchanger ◽  
Cortical Bone Mineral Density ◽  
Calbindin D

Passive paracellular proximal tubular (PT) and intestinal calcium (Ca2+) fluxes have been linked to active sodium (re)absorption. Although the epithelial sodium/proton exchanger, NHE3, mediates apical sodium entry at both these sites, its role in Ca2+ homeostasis remains unclear. We, therefore, set out to determine whether NHE3 is necessary for Ca2+ (re)absorption from these epithelia by comparing Ca2+ handling between wild-type and NHE3−/− mice. Serum Ca2+ and plasma parathyroid hormone levels were not different between groups. However, NHE3−/− mice had increased serum 1,25-dihydroxyvitamin D3. The fractional excretion of Ca2+ was also elevated in NHE3−/− mice. Paracellular Ca2+ flux across confluent monolayers of a PT cell culture model was increased by an osmotic gradient equivalent to that generated by NHE3 across the PT in vivo and by overexpression of NHE3. 45Ca2+ uptake after oral gavage and flux studies in Ussing chambers across duodenum of wild-type and NHE3−/− mice confirmed decreased Ca2+ absorption in NHE3−/− mice compared with wild-type mice. Consistent with this, intestinal calbindin-D9K, claudin-2, and claudin-15 mRNA expression was decreased. Microcomputed tomography analysis revealed a perturbation in bone mineralization. NHE3−/− mice had both decreased cortical bone mineral density and trabecular bone mass. Our results demonstrate significant alterations of Ca2+ homeostasis in NHE3−/− mice and provide a molecular link between Na+ and Ca2+ (re)absorption.

Nanocurcumin: A Double-Edged Sword for Microcancers

2020 ◽  
Vol 26 (45) ◽  
pp. 5783-5792
Author(s):  
Kholood Abid Janjua ◽  
Adeeb Shehzad ◽  
Raheem Shahzad ◽  
Salman Ul Islam ◽  
Mazhar Ul Islam
Keyword(s):  
Intracellular Signaling ◽  
Dosage Forms ◽  
The Body ◽  
In Vivo Studies ◽  
Mrna Levels ◽  
Anticancer Activities ◽  
Road Map ◽  
Anticancer Effects

There is compelling evidence that drug molecules isolated from natural sources are hindered by low systemic bioavailability, poor absorption, and rapid elimination from the human body. Novel approaches are urgently needed that could enhance the retention time as well as the efficacy of natural products in the body. Among the various adopted approaches to meet this ever-increasing demand, nanoformulations show the most fascinating way of improving the bioavailability of dietary phytochemicals through modifying their pharmacokinetics and pharmacodynamics. Curcumin, a yellowish pigment isolated from dried ground rhizomes of turmeric, exhibits tremendous pharmacological effects, including anticancer activities. Several in vitro and in vivo studies have shown that curcumin mediates anticancer effects through the modulation (upregulation and/or downregulations) of several intracellular signaling pathways both at protein and mRNA levels. Scientists have introduced multiple modern techniques and novel dosage forms for enhancing the delivery, bioavailability, and efficacy of curcumin in the treatment of various malignancies. These novel dosage forms include nanoparticles, liposomes, micelles, phospholipids, and curcumin-encapsulated polymer nanoparticles. Nanocurcumin has shown improved anticancer effects compared to conventional curcumin formulations. This review discusses the underlying molecular mechanism of various nanoformulations of curcumin for the treatment of different cancers. We hope that this study will make a road map for preclinical and clinical investigations of cancer and recommend nano curcumin as a drug of choice for cancer therapy.

scholarly journals TRIM27 interacts with Iκbα to promote the growth of human renal cancer cells through regulating the NF-κB pathway

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chengwu Xiao ◽  
Wei Zhang ◽  
Meimian Hua ◽  
Huan Chen ◽  
Bin Yang ◽  
...  
Keyword(s):  
Cell Lines ◽  
Prognostic Indicator ◽  
The Cancer Genome Atlas ◽  
Mrna Levels ◽  
Loss Of Function ◽  
Protein Levels ◽  
Kaplan Meier ◽  
Cancer Genome Atlas

Abstract Background The tripartite motif (TRIM) family proteins exhibit oncogenic roles in various cancers. The roles of TRIM27, a member of the TRIM super family, in renal cell carcinoma (RCC) remained unexplored. In the current study, we aimed to investigate the clinical impact and roles of TRIM27 in the development of RCC. Methods The mRNA levels of TRIM27 and Kaplan–Meier survival of RCC were analyzed from The Cancer Genome Atlas database. Real-time PCR and Western blotting were used to measure the mRNA and protein levels of TRIM27 both in vivo and in vitro. siRNA and TRIM27 were exogenously overexpressed in RCC cell lines to manipulate TRIM27 expression. Results We discovered that TRIM27 was elevated in RCC patients, and the expression of TRIM27 was closely correlated with poor prognosis. The loss of function and gain of function results illustrated that TRIM27 promotes cell proliferation and inhibits apoptosis in RCC cell lines. Furthermore, TRIM27 expression was positively associated with NF-κB expression in patients with RCC. Blocking the activity of NF-κB attenuated the TRIM27-mediated enhancement of proliferation and inhibition of apoptosis. TRIM27 directly interacted with Iκbα, an inhibitor of NF-κB, to promote its ubiquitination, and the inhibitory effects of TRIM27 on Iκbα led to NF-κB activation. Conclusions Our results suggest that TRIM27 exhibits an oncogenic role in RCC by regulating NF-κB signaling. TRIM27 serves as a specific prognostic indicator for RCC, and strategies targeting the suppression of TRIM27 function may shed light on future therapeutic approaches.

scholarly journals Osteoprotective Effects of Loganic Acid on Osteoblastic and Osteoclastic Cells and Osteoporosis-Induced Mice

2020 ◽  
Vol 22 (1) ◽  
pp. 233
Author(s):  
Eunkuk Park ◽  
Chang Gun Lee ◽  
Eunguk Lim ◽  
Seokjin Hwang ◽  
Seung Hee Yun ◽  
...  
Keyword(s):  
Osteoclast Differentiation ◽  
Osteoblastic Differentiation ◽  
Common Disease ◽  
Root Extract ◽  
Mouse Bone Marrow ◽  
Mineral Density ◽  
Bone Mineral Density Loss ◽  
In Vivo Experiments

Osteoporosis is a common disease caused by an imbalance of processes between bone resorption by osteoclasts and bone formation by osteoblasts in postmenopausal women. The roots of Gentiana lutea L. (GL) are reported to have beneficial effects on various human diseases related to liver functions and gastrointestinal motility, as well as on arthritis. Here, we fractionated and isolated bioactive constituent(s) responsible for anti-osteoporotic effects of GL root extract. A single phytochemical compound, loganic acid, was identified as a candidate osteoprotective agent. Its anti-osteoporotic effects were examined in vitro and in vivo. Treatment with loganic acid significantly increased osteoblastic differentiation in preosteoblast MC3T3-E1 cells by promoting alkaline phosphatase activity and increasing mRNA expression levels of bone metabolic markers such as Alpl, Bglap, and Sp7. However, loganic acid inhibited osteoclast differentiation of primary-cultured monocytes derived from mouse bone marrow. For in vivo experiments, the effect of loganic acid on ovariectomized (OVX) mice was examined for 12 weeks. Loganic acid prevented OVX-induced bone mineral density loss and improved bone structural properties in osteoporotic model mice. These results suggest that loganic acid may be a potential therapeutic candidate for treatment of osteoporosis.

scholarly journals Glucolipotoxicity and GLP-1 secretion

2021 ◽  
Vol 9 (1) ◽  
pp. e001905
Author(s):  
Jung-Hee Hong ◽  
Dae-Hee Kim ◽  
Moon-Kyu Lee
Keyword(s):  
Glucose Transporter ◽  
Cell Function ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Gene Expressions ◽  
Simultaneous Treatment ◽  
L Cells ◽  
Triglyceride Accumulation

IntroductionThe concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and/or fatty acid levels.Research design and methodsTo investigate the effects of chronic glucolipotoxicity on glucagon-like peptide-1-(7-36) amide (GLP-1) secretion, we generated glucolipotoxic conditions in human NCI-H716 enteroendocrine cells using either 5 or 25 mM glucose with or without 500 µM palmitate for 72 hours. For in vivo study, we have established a chronic nutrient infusion model in the rat. Serial blood samples were collected for 2 hours after the consumption of a mixed meal to evaluate insulin sensitivity and β-cell function.ResultsChronic glucolipotoxic conditions decreased GLP-1 secretion and the expressions of pCREB, pGSK3β, β-catenin, and TCF7L2 in NCI-H716 cells. Glucolipotoxicity conditions reduced glucose transporter expression, glucose uptake, and nicotinamide-adenine dinucleotide phosphate (NADPH) levels in L-cells, and increased triglyceride accumulation. In contrast, PPARα and ATP levels were reduced, which correlated well with decreased levels of SUR1 and Kir6.2, cAMP contents and expressions of pCAMK2, EPAC and PKA. We also observed an increase in reactive oxygen species production, UCP2 expression and Complex I activity. Simultaneous treatment with insulin restored the GLP-1 secretion. Glucolipotoxic conditions decreased insulin secretion in a time-dependent manner in INS-1 cells, which was recovered with exendin-4 cotreatment. Glucose and SMOFlipid infusion for 6 hours decreased GLP-1 secretion and proglucagon mRNA levels as well as impaired the glucose tolerance, insulin and C-peptide secretion in rats.ConclusionThese results provide evidence for the first time that glucolipotoxicity could affect GLP-1 secretion through changes in glucose and lipid metabolism, gene expressions, and proglucagon biosynthesis and suggest the interrelationship between glucolipotoxicities of L-cells and β-cells which develops earlier than that of L-cells.

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