Local action of phosphate depletion and insulin-like growth factor 1 on in vitro production of 1,25-dihydroxyvitamin D by cultured mammalian kidney cells.

Condamine, Luce; Menaa, Cheikh; Vrtovsnik, François; Friedlander, Gérard; Garabédian, M

doi:10.1172/jci117512

Cited by 99 publications

(51 citation statements)

References 47 publications

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“…Consistently, IFN-g is concentrated at the site of tuberculous pleuritis (6)(7)(8) and, in vitro, IFN-g stimulates 1,25-(OH) 2 D synthesis by macrophages (9,10). Insulin-like growth factor-I (IGF-I), which has been shown to stimulate renal 1aOHase activity (11,12), may also participate in the mechanism of control. In this regard, several investigators have reported that bone marrow-derived cells such as monocytes/macrophages and T cells, the predominant cells in tuberculous pleuritis, synthesize IGF-I (13,14).…”

Section: Introductionmentioning

confidence: 97%

Insulin-like growth factors and their binding proteins in pleural fluid

Bouc

Bellocq²,

Philippe³

et al. 1997

European Journal of Endocrinology

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We investigated the expression and potential regulatory role of insulin-like growth factors (IGFs) and their specific binding proteins (BPs) in tuberculous and nontuberculous pleuritis. By using a radioimmunoassay after acid gel filtration chromatography, we found that mean concentrations of IGF-I were 211.9Ϯ20.2 mg/l and 203.2Ϯ31.1 mg/l in pleural fluid of 14 patients with tuberculous pleuritis and 9 patients with malignant pleuritis respectively. These values were near those in serum of the same patients (221.3Ϯ19.5 mg/l and 204.6Ϯ21.0 mg/l respectively). By using a specific protein-binding assay, we found that mean concentrations of IGF-II were 345.3Ϯ61.0 mg/l and 167.6Ϯ22.7 mg/l in tuberculous and malignant pleural effusions respectively. These values were significantly lower than those in serum of the same patients (628.3Ϯ79.0 mg/l, P<0.025 and 532.0Ϯ85.9 mg/l, P<0.025 respectively). Because bioavailability and bioactivity of IGFs may be regulated by their binding to IGFBPs, we studied IGFBP patterns in the pleural fluid of 6 patients with tuberculous pleuritis. As assessed by Western ligand blotting the levels of IGFBP-1 and IGFBP-2 were increased whereas those of IGFBP-3 were decreased in pleural fluid in comparison with serum. The decrease in IGFPB-3 levels reflected increased proteolysis, as assessed by Western immunoblotting. In spite of this presence of IGFBPs, IGFs could be responsible for the local biosynthesis of 1,25-dihydroxyvitamin D (1,25-(OH) 2 D) since pleural fluid levels of both IGF-I and IGF-II significantly correlated with those of 1,25-(OH) 2 D. These results indicate that IGFs are detectable in pleural fluid and may contribute to control the activity of 25-hydroxyvitamin D-1a hydroxylase in tuberculous pleuritis.

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Section: Introductionmentioning

confidence: 97%

Insulin-like growth factors and their binding proteins in pleural fluid

Bouc

Bellocq²,

Philippe³

et al. 1997

European Journal of Endocrinology

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“…The major circulating metabolite of vitamin D is serum 25-OH vitamin D3 3 . It is the best indicator of vitamin D status and reflects levels from dietary intake and synthesis in the skin 4 .…”

Section: Introductionmentioning

confidence: 99%

Assessment of Vitamin D Status and Growth Parameters in Thalassemia Major Patients

Akhouri¹,

Neha²

2017

IOSR JDMS

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“…LLC-PK1 is a well characterized cell line that is an excellent model of the proximal tubule epithelium (19). It shares many of the key properties of native proximal tubules that CLC5 might be predicted to regulate, including expression of apical transporters such as the sodiumhydrogen exchanger, NHE3 (20), and the high affinity sodiumglucose cotransporter, SGLT1 (21), endosomal expression of megalin (22), and the vacuolar H ϩ -ATPase (23), receptor-mediated endocytosis of proteins from the luminal surface (24), and 25-hydroxyvitamin D 1-hyroxylase activity (25). We report here the cloning of a porcine CLC5 ortholog (pCLC5), its localization to Golgi and endosomal vesicles of LLC-PK1 cells, and its functional characterization by heterologous expression in the Xenopus oocyte system.…”

mentioning

confidence: 99%

Molecular Cloning and Characterization of an Intracellular Chloride Channel in the Proximal Tubule Cell Line, LLC-PK1

Dowland

Luyckx

Enck

et al. 2000

Journal of Biological Chemistry

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CLC5 is an intracellular chloride channel of unknown function, expressed in the renal proximal tubule. The subcellular localization and function of CLC5 were investigated in the LLC-PK1 porcine proximal tubule cell line. We cloned a cDNA for the porcine CLC5 ortholog (pCLC5) that is predicted to encode an 83-kDa protein with 97% amino acid sequence identity to rat and human CLC5. By immunofluorescence, pCLC5 was localized to early endosomes of the apical membrane fluid-phase endocytotic pathway and to the Golgi complex. Xenopus oocytes injected with pCLC5 cRNA exhibited outwardly rectifying whole cell currents with a relative conductance profile (nitrate > > Cl ؊ Ϸ Br ؊ > I ؊ > acetate > gluconate) different from that of control oocytes. Acidification of the extracellular medium reversibly inhibited this outward current with a pK a of 6.0 and a Hill coefficient of 1. Overexpression of CLC5 in LLC-PK1 cells resulted in morphological changes, including loss of cell-cell contacts and the appearance of multiple prominent vesicles. These findings are consistent with a potential role for CLC5 in the acidification of membrane compartments of both the endocytic and the exocytic pathway and suggest that its function may be important for normal intercellular adhesion and vesicular trafficking.

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Local action of phosphate depletion and insulin-like growth factor 1 on in vitro production of 1,25-dihydroxyvitamin D by cultured mammalian kidney cells.

Cited by 99 publications

References 47 publications

Insulin-like growth factors and their binding proteins in pleural fluid

Insulin-like growth factors and their binding proteins in pleural fluid

Assessment of Vitamin D Status and Growth Parameters in Thalassemia Major Patients

Molecular Cloning and Characterization of an Intracellular Chloride Channel in the Proximal Tubule Cell Line, LLC-PK1

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