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.

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.

scholarly journals Hormonal regulation of cholesterol 7alpha-hydroxylase specific activity, mRNA levels, and transcriptional activity in vivo in the rat

1997 ◽  
Vol 38 (12) ◽  
pp. 2483-2491 ◽  
Author(s):  
W M Pandak ◽  
D M Heuman ◽  
K Redford ◽  
R T Stravitz ◽  
J Y Chiang ◽  
...  
Keyword(s):  
Hormonal Regulation ◽  
Transcriptional Activity ◽  
Specific Activity ◽  
Mrna Levels

Synergistic effects of progesterone and oestradiol on rat LH subunit mRNA

1990 ◽  
Vol 4 (2) ◽  
pp. 119-125 ◽  
Author(s):  
M. Corbani ◽  
R. Counis ◽  
E. Wolinska-Witort ◽  
G. d'Angelo-Bernard ◽  
M. Moumni ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Synergistic Effects ◽  
Progesterone Receptors ◽  
Ovariectomized Rats ◽  
Mrna Levels ◽  
Subunit Mrna ◽  
Maximum Inhibition ◽  
Lh Release ◽  
Direct Hybridization

ABSTRACT The effects of oestradiol and progesterone on LH-subunit mRNA levels were investigated in ovariectomized rats. Four weeks after ovariectomy, rats were implanted with silicone elastomer capsules containing oestradiol and/or injected daily with progesterone in oil (5 mg/rat) for 8 days. The levels of pituitary mRNA encoding α and LH-β were determined using direct hybridization with specific [32P]cDNA probes. After oestradiol implantation in ovariectomized rats, both α and LH-β mRNA decreased with time, with maximum inhibition after 6–8 days of treatment. Progesterone injected alone did not show any effect on α and LH-β mRNA. Cytosolic progesterone receptors, determined using [3H]methyl-17α-progesterone as ligand, were undectable in control ovariectomized rats. In contrast, 2 days after oestradiol implantation, the number of receptors increased to 287·5 ± 35·4 (s.e.m.) fmol/pituitary and reached a plateau of 400 ± 21·8 fmol/pituitary after 4 days. The effects of progesterone were therefore examined by first implanting ovariectomized rats with oestradiol to induce progesterone receptors and then injecting progesterone daily for a further period of 6 days. As a result of this treatment, progesterone induced a decrease in the pituitary gland contents of both α and LH-β mRNAs, and LH release was significantly greater than that observed in the group receiving oestradiol alone. Moreover, the mRNA levels in the animals treated with oestradiol plus progesterone were lower after 8 days of treatment than those observed in ovariectomized rats treated with a tenfold higher dose of oestradiol alone. These data demonstrate that progesterone, together with oestradiol, is capable of negatively regulating the mRNAs encoding subunits in vivo, provided that progesterone receptors are present in the pituitary gland.

scholarly journals Glucocorticoids regulate mRNA levels for subunits of the 19 S regulatory complex of the 26 S proteasome in fast-twitch skeletal muscles

2004 ◽  
Vol 378 (1) ◽  
pp. 239-246 ◽  
Author(s):  
Lydie COMBARET ◽  
Daniel TAILLANDIER ◽  
Dominique DARDEVET ◽  
Daniel BÉCHET ◽  
Cécile RALLIÈRE ◽  
...  
Keyword(s):  
Hormonal Regulation ◽  
Skeletal Muscles ◽  
Conclusive Evidence ◽  
Mrna Levels ◽  
Glucocorticoid Treatment ◽  
Regulatory Subunits ◽  
Regulatory Complex ◽  
Insulin Dependent ◽  
Fast Twitch

Circulating levels of glucocorticoids are increased in many traumatic and muscle-wasting conditions that include insulin-dependent diabetes, acidosis, infection, and starvation. On the basis of indirect findings, it appeared that these catabolic hormones are required to stimulate Ub (ubiquitin)–proteasome-dependent proteolysis in skeletal muscles in such conditions. The present studies were performed to provide conclusive evidence for an activation of Ub-proteasome-dependent proteolysis after glucocorticoid treatment. In atrophying fast-twitch muscles from rats treated with dexamethasone for 6 days, compared with pair-fed controls, we found (i) increased MG132-inhibitable proteasome-dependent proteolysis, (ii) an enhanced rate of substrate ubiquitination, (iii) increased chymotrypsin-like proteasomal activity of the proteasome, and (iv) a co-ordinate increase in the mRNA expression of several ATPase (S4, S6, S7 and S8) and non-ATPase (S1, S5a and S14) subunits of the 19 S regulatory complex, which regulates the peptidase and the proteolytic activities of the 26 S proteasome. These studies provide conclusive evidence that glucocorticoids activate Ub-proteasome-dependent proteolysis and the first in vivo evidence for a hormonal regulation of the expression of subunits of the 19 S complex. The results suggest that adaptations in gene expression of regulatory subunits of the 19 S complex by glucocorticoids are crucial in the regulation of the 26 S muscle proteasome.

scholarly journals Estrogen replacement enhances insulin-induced AS160 activation and improves insulin sensitivity in ovariectomized rats

2018 ◽  
Vol 315 (6) ◽  
pp. E1296-E1304 ◽  
Author(s):  
Mizuho Kawakami ◽  
Naoko Yokota-Nakagi ◽  
Masami Uji ◽  
Ken-ichi Yoshida ◽  
Shoko Tazumi ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Glucose Transporter ◽  
Glycogen Synthase ◽  
Ovariectomized Rats ◽  
Whole Body ◽  
Similar Degree ◽  
Mrna Levels ◽  
Estrogen Replacement ◽  
Intravenous Glucose

Menopause predisposes women to impaired glucose metabolism, but the role of estrogen remains unclear. In this study, we examined the effects of chronic estrogen replacement on whole body insulin sensitivity and insulin signaling in ovariectomized rats. Female Wistar rats aged 9 wk were ovariectomized under anesthesia. After 4 wk, pellets containing either 17β-estradiol (E2) or placebo (Pla) were subcutaneously implanted in the rats. After 4 wk of treatment, the intra-abdominal fat accumulation was greater in the Pla group than that in the E2 group. Hyperinsulinemic-euglycemic clamp analysis and intravenous glucose tolerance test revealed that insulin sensitivity was significantly lower in the Pla group than in the E2 group. In addition, Western blotting showed that in vivo insulin stimulation increased protein kinase B (Akt) phosphorylation to a similar degree in the gastrocnemius and liver of both groups, but phosphorylated Akt2 Ser474 was enhanced in the muscle of the E2 group compared with the Pla group. Moreover, insulin-stimulated phosphorylation of Akt substrate of 160 kDa (AS160) Thr642 was observed only in the E2 group, resulting in the difference between the two groups. Additionally, AS160 protein and mRNA levels were higher in muscle of the E2 group than the Pla group. In contrast, E2 replacement had no effect on glucose transporter 4 protein levels in muscle and glycogen synthase kinase-3β in muscle and liver. These results suggest that estrogen replacement improves insulin sensitivity by activating the Akt2/AS160 pathway in the insulin-stimulated muscle of ovariectomized rats.

Parathyroid hormone mRNA levels are increased by progestins and vary during rat estrous cycle

1996 ◽  
Vol 270 (1) ◽  
pp. E158-E163 ◽  
Author(s):  
E. Epstein ◽  
J. Silver ◽  
G. Almogi ◽  
N. Livni ◽  
T. Naveh-Many
Keyword(s):  
Parathyroid Hormone ◽  
Estrous Cycle ◽  
Primary Cultures ◽  
Parathyroid Tissue ◽  
Ovariectomized Rats ◽  
Mrna Levels ◽  
Physiological Relevance ◽  
Weanling Rats

Estrogen increases parathyroid hormone (PTH) mRNA levels in vivo in ovariectomized rats. We now show that the 19-norprogestin R-5020 given to weanling rats or mature ovariectomized rats led to a twofold increase in thyroparathyroid PTH mRNA levels. This increase in PTH mRNA occurred at 24 and 48 h after progesterone but not at 72 h. There were no changes in serum calcium. In vitro, in primary cultures of bovine parathyroid cells, progesterone increased PTH mRNA levels threefold at 10(-8) M and twofold at 10(-9) M after 24 h. Progesterone receptor (PR) mRNA was demonstrated in rat parathyroid tissue by in situ hybridization and in human parathyroid adenoma by immunohisto-chemistry. Changes in PTH mRNA levels during the rat estrous cycle were also studied. At proestrus and estrus PTH mRNA levels were increased significantly by three- and fourfold compared with diestrus. Our results confirm that the parathyroid gland is a target organ for the ovarian sex steroids estrogen and progesterone and are of physiological relevance as shown by the changes during estrus.

scholarly journals Expression of transcellular and paracellular calcium and magnesium transport proteins in renal and intestinal epithelia during lactation

2017 ◽  
Vol 313 (3) ◽  
pp. F629-F640 ◽  
Author(s):  
Megan R. Beggs ◽  
Ida Appel ◽  
Per Svenningsen ◽  
Karsten Skjødt ◽  
R. Todd Alexander ◽  
...  
Keyword(s):  
Breast Milk ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Fractional Excretion ◽  
Transport Proteins ◽  
Transient Receptor Potential Vanilloid ◽  
Mrna Levels ◽  
Transport Pathways ◽  
Molecular Alterations ◽  
Calbindin D

Significant alterations in maternal calcium (Ca2+) and magnesium (Mg2+) balance occur during lactation. Ca2+ is the primary divalent cation mobilized into breast milk by demineralization of the skeleton and alterations in intestinal and renal Ca2+ transport. Mg2+ is also concentrated in breast milk, but the underlying mechanisms are not well understood. To determine the molecular alterations in Ca2+ and Mg2+ transport in the intestine and kidney during lactation, three groups of female mice consisting of either nonpregnant controls, lactating mice, or mice undergoing involution were examined. The fractional excretion of Ca2+, but not Mg2+, rose significantly during lactation. Renal 1-α hydroxylase and 24-OHase mRNA levels increased markedly, as did plasma 1,25 dihydroxyvitamin D levels. This was accompanied by significant increases in intestinal expression of Trpv6 and S100g in lactating mice. However, no alterations in the expression of cation-permeable claudin-2, claudin-12, or claudins-15 were found in the intestine. In the kidney, increased expression of Trpv5 and Calb1 was observed during lactation, while no changes in claudins involved in Ca2+ and Mg2+ transport (claudin-2, claudin-14, claudin-16, or claudin-19) were found. Consistent with the mRNA expression, expression of both calbindin-D28K and transient receptor potential vanilloid 5 (TRPV5) proteins increased. Colonic Trpm6 expression increased during lactation, while renal Trpm6 remained unaltered. In conclusion, proteins involved in transcellular Ca2+ and Mg2+ transport pathways increase during lactation, while expression of paracellular transport proteins remained unchanged. Increased fractional Ca2+ excretion can be explained by vitamin D-dependent intestinal hyperabsorption and bone demineralization, despite enhanced transcellular Ca2+ uptake by the kidney.

scholarly journals mRNAs Encoding Telomerase Components and Regulators Are Controlled by UPF Genes in Saccharomyces cerevisiae

2003 ◽  
Vol 2 (1) ◽  
pp. 134-142 ◽  
Author(s):  
Jeffrey N. Dahlseid ◽  
Jodi Lew-Smith ◽  
Michael J. Lelivelt ◽  
Shinichiro Enomoto ◽  
Amanda Ford ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Telomere Length ◽  
Dna Sequences ◽  
Mrna Levels ◽  
Loss Of Function ◽  
Telomeric Silencing ◽  
Expression Of Genes ◽  
Mutant Strains ◽  
Genes Encoding

ABSTRACT Telomeres, the chromosome ends, are maintained by a balance of activities that erode and replace the terminal DNA sequences. Furthermore, telomere-proximal genes are often silenced in an epigenetic manner. In Saccharomyces cerevisiae, average telomere length and telomeric silencing are reduced by loss of function of UPF genes required in the nonsense-mediated mRNA decay (NMD) pathway. Because NMD controls the mRNA levels of several hundred wild-type genes, we tested the hypothesis that NMD affects the expression of genes important for telomere functions. In upf mutants, high-density oligonucleotide microarrays and Northern blots revealed that the levels of mRNAs were increased for genes encoding the telomerase catalytic subunit (Est2p), in vivo regulators of telomerase (Est1p, Est3p, Stn1p, and Ten1p), and proteins that affect telomeric chromatin structure (Sas2p and Orc5p). We investigated whether overexpressing these genes could mimic the telomere length and telomeric silencing phenotypes seen previously in upf mutant strains. Increased dosage of STN1, especially in combination with increased dosage of TEN1, resulted in reduced telomere length that was indistinguishable from that in upf mutants. Increased levels of STN1 together with EST2 resulted in reduced telomeric silencing like that of upf mutants. The half-life of STN1 mRNA was not altered in upf mutant strains, suggesting that an NMD-controlled transcription factor regulates the levels of STN1 mRNA. Together, these results suggest that NMD maintains the balance of gene products that control telomere length and telomeric silencing primarily by maintaining appropriate levels of STN1, TEN1, and EST2 mRNA.

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