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Sylvia Christakos - One of the best experts on this subject based on the ideXlab platform.
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chapter 21 Calbindin d28k and Calbindin d9k and the epithelial calcium channels trpv5 and trpv6
Vitamin D (Fourth Edition)#R##N#Volume 1: Biochemistry Physiology and Diagnostics, 2018Co-Authors: Sylvia Christakos, Leila J Mady, Puneet DhawanAbstract:We once viewed Calbindin-D 28K and Calbindin-D 9K as exclusively vitamin D-dependent proteins. It is now evident that the Calbindins are not under the exclusive regulatory control of 1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 . Calbindin-D 28K and Calbindin-D 9K are present in many different tissues and may serve many different functions. Accordingly, the regulation of these calcium-binding proteins is varied and quite complex. The calcium-selective epithelial calcium channels, transient receptor potential vanilloid 5 and 6 (TRPV5 and TRPV6), are colocalized with Calbindin in the kidney and intestine, respectively. Studies in TRPV5 knockout (KO) mice have indicated that TRPV5 is important for renal calcium reabsorption. Calbindin-D 28K interacts with TRPV5 and regulates its activity, suggesting a role for Calbindin-D 28K as a modulator of calcium influx. Studies using Calbindin-D 9k and TRPV6 KO mice suggest that in the KO mice there is compensation by another calcium channel or protein and that other factors involved in 1,25(OH) 2 D 3 -mediated intestinal calcium absorption remain to be identified.
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Calbindin d9k is not required for 1 25 dihydroxyvitamin d3 mediated ca2 absorption in small intestine
Archives of Biochemistry and Biophysics, 2007Co-Authors: Shirin Akhter, Sylvia Christakos, Galina D Kutuzova, Hector F DelucaAbstract:Abstract The exact role of Calbindin D9k in vitamin D-mediated calcium absorption has been debated but remains unsettled. In 129/OlaHsd mice, Calbindin D9k was found highest in duodenum (36–50%) and kidney (24–34%) followed by stomach, lung and uterus. Age does not affect the relative distribution of Calbindin D9k but it does decline with age in duodenum of both male and female 129/Ola mice. Recently, we produced a null Calbindin D9k mutant 129/OlaHsd mouse; this mouse proved to be indistinguishable from the wild-type in phenotype and in a serum calcium level regardless of age or gender. We have now examined directly whether the mutant mouse can absorb calcium from the intestine in response to the active form of vitamin D. The Calbindin D9k null mutant mouse is fully able to absorb calcium from the intestine in response to 1,25-dihydroxyvitamin D3. It is, therefore, clear that Calbindin D9k is not required for vitamin D-induced intestinal calcium absorption.
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critical role of the epithelial ca2 channel trpv5 in active ca2 reabsorption as revealed by trpv5 Calbindin d28k knockout mice
Journal of The American Society of Nephrology, 2006Co-Authors: Dimitra Gkika, Sylvia Christakos, Rene J M Bindels, Yujuei Hsu, Annemiete W C M Van Der Kemp, Joost G J HoenderopAbstract:The epithelial Ca(2+) channel TRPV5 facilitates apical Ca(2+) entry during active Ca(2+) reabsorption in the distal convoluted tubule. In this process, cytosolic Ca(2+) remains at low nontoxic concentrations because the Ca(2+) influx is buffered rapidly by Calbindin-D(28K). Subsequently, Ca(2+) that is bound to Calbindin-D(28K) is shuttled toward the basolateral Ca(2+) extrusion systems. For addressing the in vivo role of TRPV5 and Calbindin-D(28K) in the maintenance of the Ca(2+) balance, single- and double-knockout mice of TRPV5 and Calbindin-D(28K) (TRPV5(-/-), Calbindin-D(28K)(-/-), and TRPV5(-/-)/Calbindin-D(28K)(-/-)) were characterized. These mice strains were fed two Ca(2+) diets (0.02 and 2% wt/wt) to investigate the influence of dietary Ca(2+) content on the Ca(2+) balance. Urine analysis indicated that TRPV5(-/-)/Calbindin-D(28K)(-/-) mice exhibit on both diets hypercalciuria compared with wild-type mice. Ca(2+) excretion in TRPV5(-/-)/Calbindin-D(28K)(-/-) mice was not significantly different from TRPV5(-/-) mice, whereas Calbindin-D(28K)(-/-) mice did not show hypercalciuria. The similarity between TRPV5(-/-)/Calbindin-D(28K)(-/-) and TRPV5(-/-) mice was supported further by an equivalent increase in renal Calbindin-D(9K) expression and in intestinal Ca(2+) hyperabsorption as a result of upregulation of Calbindin-D(9K) and TRPV6 expression in the duodenum. Elevated serum parathyroid hormone and 1,25-dihydroxyvitamin D(3) levels accompanied the enhanced expression of the Ca(2+) transporters. Intestinal Ca(2+) absorption and expression of Calbindin-D(9K) and TRPV6, as well as serum parameters of the Calbindin-D(28K)(-/-) mice, did not differ from those of wild-type mice. These results underline the gatekeeper function of TRPV5 being the rate-limiting step in active Ca(2+) reabsorption, unlike Calbindin-D(28K), which possibly is compensated by Calbindin-D(9K).
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Calbindin d9k knockout mice are indistinguishable from wild type mice in phenotype and serum calcium level
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Galina D Kutuzova, Sylvia Christakos, Shirin Akhter, Janeen L Vanhooke, Christine Kimmeljehan, Hector F DelucaAbstract:Since the discovery of Calbindin D9k, its role in intestinal calcium absorption has remained unsettled. Further, a wide distribution of Calbindin D9k among tissues has argued for its biological importance. We discovered a frameshift deletion in the Calbindin D9k gene in an ES cell line, E14.1, that originated from 129/OlaHsd mice. We produced mice with the mutant Calbindin D9k gene by injecting the E14.1 ES cell subline into the C57BL/6 host blastocysts and proved that these mice lack Calbindin D9k protein. Calbindin D9k knockout mice were indistinguishable from wild-type mice in phenotype, were able to reproduce, and had normal serum calcium levels. Thus, Calbindin D9k is not required for viability, reproduction, or calcium homeostasis.
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expression of Calbindin d28k in a pancreatic isletβ cell line protects against cytokine induced apoptosis and necrosis
Endocrinology, 2001Co-Authors: Alex Rabinovitch, Wilma L Suarezpinzon, Karen Sooy, Ken Strynadka, Sylvia ChristakosAbstract:Cytokines produced by immune system cells that infiltrate pancreatic islets are candidate mediators of islet β-cell destruction in autoimmune (type 1) diabetes mellitus. Because the calcium binding protein, Calbindin-D28k, can prevent apoptotic cell death in different cell types, we investigated the possibility that Calbindin-D28k may prevent cytokine-mediated islet β-cell destruction. Using the expression vector BSRα, rat Calbindin-D28k was stably expressed in the pancreatic isletβ -cell line, βTC-3. Calbindin-D28k expression resulted in increased cell survival in the presence of the cytotoxic combination of the cytokines IL-1β (30 U/ml), TNFα (103 U/ml), and interferon γ (103 U/ml). The greatest protection was observed in the βTC-3 cell clone expressing the highest concentration of Calbindin-D28k. Apoptotic cell death was detected by annexin V staining and by the TdT-mediated dUTP-X nick end labeling assay in vector-transfected βTC-3 cells incubated with cytokines (14–15% apoptotic cells). The number of...
Hector F Deluca - One of the best experts on this subject based on the ideXlab platform.
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Calbindin d9k is not required for 1 25 dihydroxyvitamin d3 mediated ca2 absorption in small intestine
Archives of Biochemistry and Biophysics, 2007Co-Authors: Shirin Akhter, Sylvia Christakos, Galina D Kutuzova, Hector F DelucaAbstract:Abstract The exact role of Calbindin D9k in vitamin D-mediated calcium absorption has been debated but remains unsettled. In 129/OlaHsd mice, Calbindin D9k was found highest in duodenum (36–50%) and kidney (24–34%) followed by stomach, lung and uterus. Age does not affect the relative distribution of Calbindin D9k but it does decline with age in duodenum of both male and female 129/Ola mice. Recently, we produced a null Calbindin D9k mutant 129/OlaHsd mouse; this mouse proved to be indistinguishable from the wild-type in phenotype and in a serum calcium level regardless of age or gender. We have now examined directly whether the mutant mouse can absorb calcium from the intestine in response to the active form of vitamin D. The Calbindin D9k null mutant mouse is fully able to absorb calcium from the intestine in response to 1,25-dihydroxyvitamin D3. It is, therefore, clear that Calbindin D9k is not required for vitamin D-induced intestinal calcium absorption.
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Calbindin d9k knockout mice are indistinguishable from wild type mice in phenotype and serum calcium level
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Galina D Kutuzova, Sylvia Christakos, Shirin Akhter, Janeen L Vanhooke, Christine Kimmeljehan, Hector F DelucaAbstract:Since the discovery of Calbindin D9k, its role in intestinal calcium absorption has remained unsettled. Further, a wide distribution of Calbindin D9k among tissues has argued for its biological importance. We discovered a frameshift deletion in the Calbindin D9k gene in an ES cell line, E14.1, that originated from 129/OlaHsd mice. We produced mice with the mutant Calbindin D9k gene by injecting the E14.1 ES cell subline into the C57BL/6 host blastocysts and proved that these mice lack Calbindin D9k protein. Calbindin D9k knockout mice were indistinguishable from wild-type mice in phenotype, were able to reproduce, and had normal serum calcium levels. Thus, Calbindin D9k is not required for viability, reproduction, or calcium homeostasis.
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1 25 dihydroxyvitamin d and not calcium is the major regulator of Calbindin d 9 kda mrna levels in vivo
Experimental Biology and Medicine, 1992Co-Authors: Molly Strom, John Krisinger, Hisham M Darwish, Hector F DelucaAbstract:AbstractA possible role of calcium in vivo on intestinal Calbindin-D 9-kDa mRNA levels has been studied in rats. In vitamin D-deficient rats, a marked increase in dietary calcium has a small but significant effect on Calbindin-D 9-kDa mRNA levels, despite a dramatic increase in serum calcium concentration that clearly resulted from increased intestinal absorption of calcium. On the other hand, vitamin D under all circumstances increased Calbindin-D 9-kDa mRNA levels, with the greatest levels found in animals on a low calcium diet where little or no calcium is available for absorption. These results strongly support the idea that 1,25-dihydroxyvitamin D is directly responsible for the induction of Calbindin-D 9-kDa. [P.S.E.B.M. 1992, Vol 199]
H J Armbrecht - One of the best experts on this subject based on the ideXlab platform.
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capacity of 1 25 dihydroxyvitamin d to stimulate expression of Calbindin d changes with age in the rat
Archives of Biochemistry and Biophysics, 1998Co-Authors: Sylvia Christakos, H J Armbrecht, M A Boltz, M E BrunsAbstract:Abstract Studies in rats and humans have shown that there is an age-related decline in the stimulation of intestinal Ca transport by 1,25-dihydroxyvitamin D 3 [1,25(OH) 2 D], the active metabolite of vitamin D. The Calbindins are a family of vitamin D-dependent calcium-binding proteins found in the intestine (Calbindin D-9k) and kidney (Calbindin D-28k) and are thought to play a role in calcium transport and homeostasis. The purpose of this study was to determine if the capacity of 1,25(OH) 2 D to stimulate the expression of Calbindin protein and mRNA changes with age. Young (2 months), adult (12 months), and old (22 months) male F344 rats were made deficient in 1,25(OH) 2 D by being fed a strontium-containing diet and then being given a single ip injection of 1,25(OH) 2 D. Calbindin protein levels were measured by immunological techniques using specific antisera, and mRNA levels were measured by Northern and dot blots. The maximal amount of Calbindin D-9k protein induced by 1,25(OH) 2 D declined with age in the duodenum but not in the ileum. In time-course studies, there was a delay in Calbindin D-9k induction in the duodenum but not in the ileum of adult rats compared to young rats. In contrast to protein induction, maximal Calbindin D-9k mRNA levels in response to 1,25(OH) 2 D were greater in the adult animal and showed no time lag compared to those in the young animal. In the kidney, maximal levels of renal Calbindin D-28k protein and mRNA did not change with age, but there was delayed induction in the adult. These studies demonstrate that there is an age-related decrease in the induction of Calbindin protein in response to 1,25(OH) 2 D in the duodenum, but not in the ileum or kidney. This decline may be due to decreased translation of Calbindin D-9k mRNA into protein in the duodenum with age.
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age related alterations in Calbindin d28k induction by 1 25 dihydroxyvitamin d3 in primary cultures of rat renal tubule cells
Endocrinology, 1992Co-Authors: M L Chen, S Christakos, M A Boltz, H J ArmbrechtAbstract:In vivo studies have indicated that renal Calbindin-D28K protein and mRNA levels decrease in adult and old rats, and this decrease parallels the age-associated decline in serum 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] levels. However, diminished renal responsiveness to 1,25-(OH)2D3 with advancing age could also contribute to decreased Calbindin-D28K expression. To study renal responsiveness with age, primary cell cultures were established from the kidney cortices of young (1 month old), adult (10-12 months old), and old (20-24 months old) rats. Cells were incubated in medium K-1 containing 2% fetal calf serum. Calbindin-D28K protein levels were determined by Western blot and enzyme-linked immunosorbent assay. In young animals, the levels of Calbindin-D28K declined from 12.1 +/- 1.3 micrograms/mg protein in the intact kidney to 1.6 +/- 0.07 micrograms/mg protein in cells that had been cultured for 3 days in the absence of 1,25-(OH)2D3. This sharp decline in Calbindin-D28K protein concentration moderated by days 6-8. The continuous presence of 10(-7) M 1,25-(OH)2D3 in the medium did not abolish the decline. The low levels of Calbindin-D28K in the cells cultured in the absence of 1,25-(OH)2D3 provided an excellent experimental system in which to compare the response of the cells to 1,25-(OH)2D3 between age groups. In cultured cells treated with 1,25-(OH)2D3 for 72 h, Calbindin-D28K induction was greater in cells from adult and old animals compared to cells from young animals. The ratios of Calbindin-D28K content (with vitamin D/without vitamin D) were 2.2 +/- 0.2, 4.7 +/- 0.5, and 7.1 +/- 1.5 for young, adult, and old cells, respectively. These studies suggested that the observed in vivo decrease in renal Calbindin-D28K with age is primarily due to the lowered circulating 1,25-(OH)2D3.
Bernard Droz - One of the best experts on this subject based on the ideXlab platform.
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Calbindin d 28k and substance p immunoreactive primary sensory neurons peripheral projections in chick hindlimbs
The Journal of Comparative Neurology, 1993Co-Authors: Christophe Duc, Ibtissam Barakatwalter, Bernard DrozAbstract:The peripheral projections of two distinct subpopulations of primary sensory neurons, expressing either Calbindin D-28k or substance P, were studied in chick hindlimbs by immunodetecting Calbindin D-28k with a rabbit antiserum and substance P with a mouse monoclonal antibody. Calbindin D-28k-immunoreactive axons provided an innervation restricted to specific mechanoreceptors such as muscle spindles, Herbst and Merkel corpuscles, or collars of feather follicles but were absent from Golgi tendon organs. In contrast, substance P-positive axons spread out diffusely in muscles and skin, formed loose plexuses, and extended free branches to the endomysium, arteries, superficial dermis, or dermal pulp of feather follicles. The present results show that Calbindin D-28k- and substance P-immunoreactive primary sensory neurons provide distinct modes of innervation to selective targets in peripheral tissues. The results suggest a possible correlation between CaBP-expressing nerve endings and rapidly adapting mechanoreceptors. © 1993 Wiley-Liss, Inc.
Yeong Hau H Lien - One of the best experts on this subject based on the ideXlab platform.
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cyclosporine a induced hypercalciuria in Calbindin d28k knockout and wild type mice
Kidney International, 2002Co-Authors: Chien Te Lee, Li Wen Lai, Viet M Huynh, Yeong Hau H LienAbstract:Cyclosporine A-induced hypercalciuria in Calbindin-D28k knockout and wild-type mice. Background It is known that cyclosporine A (CsA) treatment induces high bone-turnover osteopenia and hypercalciuria. It has been proposed that down-regulation of renal Calbindin-D28k by CsA results in renal calcium wasting. We investigated the role of the kidney and bone in CsA-induced hypercalciuria in Calbindin-D28k knockout (KO) and wild-type (WT) mice. Methods Two sets of experiments were performed. In experiment 1, KO and WT mice were treated with CsA 20 mg/kg/day intraperitoneally (IP) for 7 days. In experiment 2, to eliminate the CsA effect on bone resorption, pamidronate (APD) 2.5 mg/kg IP was given every 4 days with the first dose given 4 days prior to the 7-day course of CsA. Serum levels of creatinine, calcium, and osteocalcin, as well as renal calcium excretion were measured to assess CsA's effects on calcium homeostasis. Effects of CsA on the expression of Calbindin-D28k, and two calcium channels in the apical membrane of the distal tubule, epithelial calcium channel (ECaC) and α1G-subunit of a voltage-dependent Ca channel (α1G), in the kidney were examined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). Results KO mice had a threefold increase in renal calcium excretion when compared with WT mice at the baseline. This difference disappeared when calcium load was reduced by overnight fasting. After the CsA treatment, both WT and KO mice had a significant increase of renal calcium excretion (urine Ca/Cr ratio in WT, 0.11 ± 0.01 to 1.29 ± 0.17; in KO, 0.39 ± 0.04 to 1.18 ± 0.13; both P P P Conclusion Calbindin-D28k KO mice have diet-dependent hypercalciuria and a lower bone turnover rate. CsA treatment suppresses the expression of Calbindin-D28k in mice, but has no effects on ECaC and α1G gene expression at the mRNA level. The pathogenesis of CsA-induced hypercalciuria involves both down-regulation of Calbindin-D28k with subsequent impaired renal calcium reabsorption and CsA-induced high turnover bone disease. Additionally, our results suggest that mechanism(s) independent of Calbindin-D28k within the kidney also may contribute to the CsA-induced calcium leak.
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cytoprotective effects of Calbindin d28k against antimycin a induced hypoxic injury in proximal tubular cells
Life Sciences, 2002Co-Authors: Li Wen Lai, Yeong Hau H LienAbstract:Intracellular calcium plays an important role on the pathogenesis of hypoxia-induced cellular injury. Calbindin-D(28k), a cytosolic vitamin D-dependent calcium binding protein, can serve as a buffer to limit a surge in intracellular Ca2+ concentration ([Ca2+]i) induced by various stimulations. To evaluate the possible cytoprotective effect of Calbindin-D(28k) against hypoxic injury in proximal tubular cells, a plasmid containing Calbindin-D(28k) cDNA under the control of CMV immediate-early gene promoter was transfected into the murine proximal tubular epithelial (MCT) cells. The expression of Calbindin-D(28k) in the transfected cells was verified with Northern blot analysis, Western blot analysis, and immunofluorescent staining. The non-transfected and transfected MCT cells were subjected to chemical hypoxia induced by antimycin A (10 microM) and glucose deprivation for 30-120 min. The transfection of Calbindin-D(28k) reduced lactate dehydrogenase (LDH) release by 41%, 41%, 24%, and 24%, respectively, at 30, 60, 90 and 120 min after hypoxia when compared to the non-transfected cells (all p < 0.05). Cell viability after hypoxic injury was also significantly higher in transfected cells than non-transfected cells. Transfection with the plasmid without Calbindin-D(28k) cDNA did not affect LDH release or cell viability after chemical hypoxic injury. [Ca+2]i was measured ratiometrically with fura-2 after exposure to chemical hypoxia. The rate of initial rise in [Ca2+]i and final [Ca+2]i at 30-120 min were significantly lowered in transfected cells. In conclusion, this study demonstrated that transfection of Calbindin-D(28k) gene into MCT cells provide protective effects against chemical hypoxic injury probably through its buffering effects on [Ca+2]i.