scholarly journals Sclerostin directly stimulates osteocyte synthesis of fibroblast growth factor-23

2020 ◽  
Author(s):  
Nobuaki Ito ◽  
Matthew Prideaux ◽  
Asiri R. Wijenayaka ◽  
Dongqing Yang ◽  
Renee T. Ormsby ◽  
...  
Keyword(s):  
Growth Factor ◽  
Mrna Expression ◽  
Fibroblast Growth Factor ◽  
Cell Model ◽  
Ex Vivo ◽  
Fibroblast Growth Factor 23 ◽  
Mrna Levels ◽  
Fibroblast Growth ◽  
Pi Homeostasis

AbstractOsteocyte produced fibroblast growth factor 23 (FGF23) is the key regulator of serum phosphate (Pi) homeostasis. The interplay between parathyroid hormone (PTH), FGF23 and other proteins that regulate FGF23 production and serum Pi levels is complex and incompletely characterised. Evidence suggests that the protein product of the SOST gene, sclerostin (SCL), also a PTH target and also produced by osteocytes, plays a role in FGF23 expression, however the mechanism for this effect is unclear. Part of the problem of understanding the interplay of these mediators is the complex multi-organ system that achieves Pi homeostasis in vivo. In the current study, we sought to address this using a unique cell line model of the osteocyte, IDG-SW3, known to express FGF23 at both the mRNA and protein levels. In cultures of differentiated IDG-SW3 cells, both PTH1-34 and recombinant human (rh) SCL remarkably induced Fgf23 mRNA expression dose-dependently within 3 hours. Both rhPTH1-34 and rhSCL also strongly induced C-terminal FGF23 protein secretion. Secreted intact FGF23 levels remained unchanged, consistent with constitutive post-translational cleavage of FGF23 in this cell model. Both rhPTH1-34 and rhSCL treatments significantly suppressed mRNA levels of Phex, Dmp1 and Enpp1 mRNA, encoding putative negative regulators of FGF23 levels, and induced Galnt3 mRNA expression, encoding N-acetylgalactosaminyl-transferase 3 (GalNAc-T3), which protects FGF23 from furin-like proprotein convertase-mediated cleavage. The effect of both rhPTH1-34 and rhSCL was antagonised by pre-treatment with the NF-κβ signalling inhibitors, BAY11 and TPCK. RhSCL also stimulated FGF23 mRNA expression in ex vivo cultures of human bone. These findings provide evidence for the direct regulation of FGF23 expression by sclerostin. Locally expressed sclerostin via the induction of FGF23 in osteocytes thus has the potential to contribute to the regulation of Pi homeostasis.

Fibroblast growth factor 23 production in bone is directly regulated by 1α,25-dihydroxyvitamin D, but not PTH

2010 ◽  
Vol 299 (5) ◽  
pp. F1212-F1217 ◽  
Author(s):  
Fumie Saji ◽  
Takashi Shigematsu ◽  
Toshifumi Sakaguchi ◽  
Masaki Ohya ◽  
Hikari Orita ◽  
...  
Keyword(s):  
Growth Factor ◽  
Renal Insufficiency ◽  
Mrna Expression ◽  
Fibroblast Growth Factor ◽  
Fibroblast Growth Factor 23 ◽  
Mrna Levels ◽  
Fibroblast Growth ◽  
Dihydroxyvitamin D ◽  
Fgf23 Concentration ◽  
Group A

Fibroblast growth factor 23 (FGF23), which is primarily produced by osteocytes in bone, regulates renal phosphate excretion and 1α,25-dihydroxyvitamin D [1,25(OH)2D3] metabolism. Patients with chronic kidney disease (CKD) have increased levels of circulating serum FGF23, but the direct effect on circulating FGF23 levels in renal insufficiency is still unclear. To identify the major regulator of FGF23 synthesis in renal insufficiency, we compared the effect of parathyroid hormone (PTH) and 1,25(OH)2D3 on FGF23 synthesis in the calvariae of normal rats with that of uremic rats in vitro. 1,25(OH)2D3 treatment significantly increased the FGF23 concentration in the medium from both groups, but the degree of increase in the uremic group was markedly higher than in the control group. A significant increase in FGF23 mRNA expression occurred as early as 4 h after treatment and reached the maximum within 8 h in the uremic group, whereas in the normal group a significant increase in FGF23 mRNA expression was observed only at 8 h. In addition, the expression of vitamin D receptor (VDR) mRNA in the calvariae of uremic rats was markedly higher than in normal rats. However, in neither group did PTH treatment affect the medium FGF23 concentration or the FGF23 mRNA levels. These results suggest that FGF23 synthesis in bone is regulated by 1,25(OH)2D3 directly, not by PTH, and that increased VDR mRNA expression induced the relatively swift and strong response in the uremic group.

Fibroblast Growth Factor 23 (FGF23) Induces Ventricular Arrhythmias and Prolongs QTc Interval in Mice in an FGF Receptor 4-Dependent Manner

2021 ◽  
Author(s):  
Jonah M. Graves ◽  
Julian A. Vallejo ◽  
Chelsea S. Hamill ◽  
Derek Wang ◽  
Rohan Ahuja ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Ventricular Arrhythmias ◽  
Ex Vivo ◽  
Fibroblast Growth Factor 23 ◽  
Left Ventricular ◽  
Qtc Interval ◽  
Fibroblast Growth ◽  
Fgf Receptor

Fibroblast growth factor 23 (FGF23) is a phosphate regulating protein hormone released by osteocytes. FGF23 becomes markedly elevated in chronic kidney disease (CKD), for which the leading cause of death is cardiovascular disease, particularly sudden cardiac death. Previously, we found that FGF23 increases intracellular Ca2+ in cardiomyocytes and alters contractility in mouse ventricles ex vivo via FGF-receptor 4 (FGFR4). In the present study, we demonstrate that FGF23 induces cardiac arrhythmias and prolongs QTc interval in mice, and we tested whether these effects are mediated through FGFR4. In isolated Langendorff perfused hearts, FGF23 perfusion increased mechanical arrhythmias in the form of premature ventricular beats (PVBs), and induced runs of ventricular tachycardia in six of 11 animals, which were attenuated with pretreatment of an anti-FGFR4 blocking antibody. Ex vivo ECG analysis of isolated intact hearts showed increased ventricular arrhythmias and QTc prolongation after FGF23 infusion compared to vehicle. In vivo, injection of FGF23 into the jugular vein led to the emergence of premature ventricular contractions (PVCs) in 5 out of 11 experiments. FGF23 also produced a significant lengthening effect upon QTc interval in vivo. In vivo FGFR4 blockade ameliorated the arrhythmogenic and QTc prolonging effects of FGF23. Finally, FGF23 increased cardiomyocyte Ca2+ levels in intact left ventricular muscle which was inhibited by FGR4 blockade. We conclude that FGF23/FGFR4 signaling in the heart may contribute to ventricular arrhythmogenesis and repolarization disturbances commonly observed in patients with CKD via Ca2+ overload and may be an important therapeutic target to reduce cardiac mortality in CKD.

scholarly journals 1α,25-dihydroxyvitamin D3 acts predominately in mature osteoblasts under conditions of high extracellular phosphate to increase fibroblast growth factor 23 production in vitro

2010 ◽  
Vol 206 (3) ◽  
pp. 279-286 ◽  
Author(s):  
Ryoko Yamamoto ◽  
Tomoko Minamizaki ◽  
Yuji Yoshiko ◽  
Hirotaka Yoshioka ◽  
Kazuo Tanne ◽  
...  
Keyword(s):  
Growth Factor ◽  
Mrna Expression ◽  
Fibroblast Growth Factor ◽  
Fibroblast Growth Factor 23 ◽  
Prostaglandin E ◽  
Mrna Levels ◽  
Fibroblast Growth ◽  
Dihydroxyvitamin D3 ◽  
Osteoblast Development

Osteoblasts/osteocytes are the principle sources of fibroblast growth factor 23 (FGF23), a phosphaturic hormone, but the regulation of FGF23 expression during osteoblast development remains uncertain. Because 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) and inorganic phosphate (Pi) may act as potent activators of FGF23 expression, we estimated how these molecules regulate FGF23 expression during rat osteoblast development in vitro. 1,25(OH)2D3-dependent FGF23 production was restricted largely to mature cells in correlation with increased vitamin D receptor (VDR) mRNA levels, in particular, when Pi was present. Pi alone and more so in combination with 1,25(OH)2D3 increased FGF23 production and VDR mRNA expression. Parathyroid hormone, stanniocalcin 1, prostaglandin E2, FGF2, and foscarnet did not increase FGF23 mRNA expression. Thus, these results suggest that 1,25(OH)2D3 may exert its largest effect on FGF23 expression/production when exposed to high levels of extracellular Pi in osteoblasts/osteocytes.

Fibroblast Growth Factor 23 (FGF23) leads to endolysosomal routing of the renal phosphate co-transporters NaPi-IIa and NaPi-IIc in vivo

2021 ◽  
Author(s):  
Catharina J Küng ◽  
Betül Haykir ◽  
Udo Schnitzbauer ◽  
Daniela Egli-Spichtig ◽  
Nati Hernando ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Time Course ◽  
Fibroblast Growth Factor 23 ◽  
Fibroblast Growth ◽  
Extracellular Signal ◽  
Early Endosomes ◽  
Lysosomal Proteases ◽  
Intracellular Pathway

The sodium-dependent phosphate co-transporters NaPi-IIa and NaPi-IIc located at the brush border membrane of renal proximal tubules are regulated by numerous factors, including fibroblast growth factor 23 (FGF23). FGF23 downregulates NaPi-IIa and NaPi-IIc abundance after activating a signaling pathway involving phosphorylation of the extracellular signal-regulated protein kinase (phospho-ERK1/2). FGF23 also downregulates the expression of renal 1-α-hydroxylase (Cyp27b1) and upregulates 24-hydroxylase (Cyp24a1), thus reducing plasma calcitriol levels. Here, we examined the time course of the FGF23-induced internalization of NaPi-IIa and NaPi-IIc and their intracellular pathway towards degradation in vivo. Mice were injected intraperitoneally with recombinant human FGF23 (rh-FGF23) in the absence (biochemical analysis) or presence (immunohistochemistry) of leupeptin, an inhibitor of lysosomal proteases. Phosphorylation of ERK1/2 was enhanced 60 minutes after rh-FGF23 administration, and increased phosphorylation was still detected 480 minutes post-injection. Co-localization of phospho-ERK1/2 with NaPi-IIa was seen at 60, 120 and partly at 480 minutes. The abundance of both co-transporters was reduced 240 minutes after rh-FGF23 administration, with a further reduction at 480 minutes. NaPi-IIa and NaPi-IIc were found to co-localize with clathrin and early endosomal antigen 1 (EEA1) as early as 120 minutes after rh-FGF23 injection. Both co-transporters partially co-localized with cathepsin B and Lamp1, markers of lysosomes, 120 minutes after rh-FGF23 injection. Thus, NaPi-IIa and NaPi-IIc are internalized within 2 hours upon rh-FGF23 injection. Both co-transporters share the pathway of clathrin-mediated endocytosis that leads first to early endosomes, finally resulting in trafficking towards the lysosome as early as 120 minutes after rh-FGF23 administration.

scholarly journals Direct and indirect effects of parathyroid hormone on circulating levels of fibroblast growth factor 23 in vivo

2011 ◽  
Vol 80 (5) ◽  
pp. 475-482 ◽  
Author(s):  
Ignacio López ◽  
M. Encarnación Rodríguez-Ortiz ◽  
Yolanda Almadén ◽  
Fátima Guerrero ◽  
A. Montes de Oca ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Indirect Effects ◽  
Fibroblast Growth Factor 23 ◽  
Fibroblast Growth ◽  
Direct And Indirect Effects ◽  
Circulating Levels

scholarly journals FGF23 impairs peripheral microvascular function in renal failure

2018 ◽  
Vol 315 (5) ◽  
pp. H1414-H1424 ◽  
Author(s):  
Melissa Verkaik ◽  
Rio P. Juni ◽  
Ellen P. M. van Loon ◽  
Erik M. van Poelgeest ◽  
Rick F. J. Kwekkeboom ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Endothelial Cells ◽  
Growth Factor ◽  
Endothelial Dysfunction ◽  
Kidney Disease ◽  
Asymmetric Dimethylarginine ◽  
Ex Vivo ◽  
Fibroblast Growth Factor 23 ◽  
Fibroblast Growth

Cardiovascular diseases account for ~50% of mortality in patients with chronic kidney disease (CKD). Fibroblast growth factor 23 (FGF23) is independently associated with endothelial dysfunction and cardiovascular mortality. We hypothesized that CKD impairs microvascular endothelial function and that this can be attributed to FGF23. Mice were subjected to partial nephrectomy (5/6Nx) or sham surgery. To evaluate the functional role of FGF23, non-CKD mice received FGF23 injections and CKD mice received FGF23-blocking antibodies after 5/6Nx surgery. To examine microvascular function, myocardial perfusion in vivo and vascular function of gracilis resistance arteries ex vivo were assessed in mice. 5/6Nx surgery blunted ex vivo vasodilator responses to acetylcholine, whereas responses to sodium nitroprusside or endothelin were normal. In vivo FGF23 injections in non-CKD mice mimicked this endothelial defect, and FGF23 antibodies in 5/6Nx mice prevented endothelial dysfunction. Stimulation of microvascular endothelial cells with FGF23 in vitro did not induce ERK phosphorylation. Increased plasma asymmetric dimethylarginine concentrations were increased by FGF23 and strongly correlated with endothelial dysfunction. Increased FGF23 concentration did not mimic impaired endothelial function in the myocardium of 5/6Nx mice. In conclusion, impaired peripheral endothelium-dependent vasodilatation in 5/6Nx mice is mediated by FGF23 and can be prevented by blocking FGF23. These data corroborate FGF23 as an important target to combat cardiovascular disease in CKD.NEW & NOTEWORTHY In the present study, we provide the first evidence that fibroblast growth factor 23 (FGF23) is a cause of peripheral endothelial dysfunction in a model of early chronic kidney disease (CKD) and that endothelial dysfunction in CKD can be prevented by blockade of FGF23. This pathological effect on endothelial cells was induced by long-term exposure of physiological levels of FGF23. Mechanistically, increased plasma asymmetric dimethylarginine concentrations were strongly associated with this endothelial dysfunction in CKD and were increased by FGF23.

scholarly journals The emerging role of the fibroblast growth factor-23–klotho axis in renal regulation of phosphate homeostasis

2007 ◽  
Vol 194 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Mohammed S Razzaque ◽  
Beate Lanske
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Fibroblast Growth Factor 23 ◽  
Ion Homeostasis ◽  
Experimental Studies ◽  
Receptor Activation ◽  
Fibroblast Growth ◽  
Phosphate Homeostasis ◽  
Downstream Signaling

Normal mineral ion homeostasis is tightly controlled by numerous endocrine factors that coordinately exert effects on intestine, kidney, and bone to maintain physiological balance. The importance of the fibroblast growth factor (FGF)-23–klotho axis in regulating mineral ion homeostasis has been proposed from recent research observations. Experimental studies suggest that 1) FGF23 is an important in vivo regulator of phosphate homeostasis, 2) FGF23 acts as a counter regulatory hormone to modulate the renal 1α-hydroxylase and sodium–phosphate cotransporter activities, 3) there is a trend of interrelationship between FGF23 and parathyroid hormone activities, 4) most of the FGF23 functions are conducted through the activation of FGF receptors, and 5) such receptor activation needs klotho, as a cofactor to generate downstream signaling events. These observations clearly suggest the emerging roles of the FGF23–klotho axis in maintaining mineral ion homeostasis. In this brief article, we will summarize how the FGF23–klotho axis might coordinately regulate normal mineral ion homeostasis, and how their abnormal regulation could severely disrupt such homeostasis to induce disease pathology.

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