Development and Validation of a Simple Diagnostic Method to Detect Gain and Loss of Function Defects in Fibroblast Growth Factor-23

2016 ◽  
Vol 86 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Ahmad R. Ramadan ◽  
Said M. Shawar ◽  
Manal A. Alghamdi
2006 ◽  
Vol 91 (10) ◽  
pp. 4037-4042 ◽  
Author(s):  
Holly J. Garringer ◽  
Corinne Fisher ◽  
Tobias E. Larsson ◽  
Siobhan I. Davis ◽  
Daniel L. Koller ◽  
...  

Abstract Context: Familial tumoral calcinosis (TC) results from disruptions in phosphate metabolism and is characterized by high serum phosphate with normal or elevated 1,25 dihydroxyvitamin vitamin D concentrations and ectopic and vascular calcifications. Recessive loss-of-function mutations in UDP-N-acetyl-α-d-galactosamine-polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3) and fibroblast growth factor-23 (FGF23) result in TC. Objective: The objective of the study was to determine the relationship between GALNT3 and FGF23 in familial TC. Design, Setting, and Patients: We assessed the major biochemical defects and potential genes involved in patients with TC. Intervention: Combination therapy consisted of the phosphate binder Sevelamer and the carbonic anhydrase inhibitor acetazolamide. Results: We report a patient homozygous for a GALNT3 exon 1 deletion, which is predicted to truncate the encoded protein. This patient had high serum FGF23 concentrations when assessed with a C-terminal FGF23 ELISA but low-normal FGF23 levels when tested with an ELISA for intact FGF23 concentrations. Matrix extracellular phosphoglycoprotein has been identified as a possible regulator of phosphate homeostasis. Serum matrix extracellular phosphoglycoprotein levels, however, were normal in the family with GALNT3-TC and a kindred with TC carrying the FGF23 S71G mutation. The tumoral masses of the patient with GALNT3-TC completely resolved after combination therapy. Conclusions: Our findings demonstrate that GALNT3 inactivation in patients with TC leads to inadequate production of biologically active FGF23 as the most likely cause of the hyperphosphatemic phenotype. Furthermore, combination therapy may be effective for reducing the tumoral burden associated with familial TC.


2019 ◽  
Vol 8 (4) ◽  
pp. 500 ◽  
Author(s):  
Ernesto Martín-Núñez ◽  
Javier Donate-Correa ◽  
Caroline Kannengiesser ◽  
David-Paul De Brauwere ◽  
Christine Leroy ◽  
...  

Hyperphosphatemia is commonly present in end-stage renal disease. Klotho (KL) is implicated in phosphate homeostasis since it acts as obligate co-receptor for the fibroblast growth factor 23 (FGF23), a major phosphaturic hormone. We hypothesized that genetic variation in the KL gene might be associated with alterations in phosphate homeostasis resulting in hyperphosphatemia. We performed sequencing for determining KL gene variants in a group of resistant hyperphosphatemic dialysis patients. In a 67-year-old female, blood DNA sequencing revealed a heterozygous deletion of a T at position 1041 (c.1041delT) in exon 2. This variation caused a frameshift with substitution of isoleucine for phenylalanine and introduction of a premature termination codon (p.Ile348Phefs*28). cDNA sequencing showed absence of deletion-carrier transcripts in peripheral blood mononuclear cells suggesting degradation of these through a nonsense-mediated RNA decay pathway. Experiments in vitro showed that p.Ile348Phefs*28 variant impaired FGF23 signaling pathway, indicating a functional inactivation of the gene. In the patient, serum levels of KL were 2.9-fold lower than the mean level of a group of matched dialysis subjects, suggesting a compromise in the circulating protein concentration due to haploinsufficiency. These findings provide a new loss-of-function variant in the human KL gene, suggesting that genetic determinants might be associated to clinical resistant hyperphosphatemia.


2020 ◽  
Author(s):  
Jun Gu ◽  
Jian-an Pan ◽  
Jian-ying Yu ◽  
Hao Lin ◽  
Hui-li Zhang ◽  
...  

Abstract Background A relationship between the abundance of epicardial adipose tissue (EAT) and the risk of atrial fibrillation (AF) in diabetes mellitus (DM) has been reported. And browning of EAT might be a novel approach for prevention or treatment in AF by adjusting atrial fibrosis. MicroRNA-21 (miR-21) is one of the most important miRs, and previous studies have shown that it is a regulatory factor in atrial fibrosis and AF. The aim of this study was to examine the role of different subtypes of miR-21 in EAT browning and atrial fibrosis under hyperglycemia conditions. Methods The expression of serum hsa-miR-21-3p and hsa-miR-21-5p in patients with DM and/or AF were determined by quantitative reverse transcription-polymerase chain reaction. And normal C57BL/6 wild type (WT) and miR-21 knockout (KO) mice were used to establish the diabetic model by intraperitoneal injection of streptozotocin (STZ). In vitro, The EAT adipocytes from miR-21 KO mice were cultured and transfected with miR-21-3p mimic or miR-21-5p mimic and co-cultured with atrial fibroblasts in both HG or LG conditions. The browning of EAT and the fibrosis of fibroblasts were assessed by western blotting, immunofluorescence, Masson staining, and ELISA. Finally, the gain- and loss-of-function experiments were used to identified fibroblast growth factor receptor 1 (FGFR1) as the target gene of miR-21-3p, and the regulatory pathway of miR-21-3p FGFR1, fibroblast growth factor 21 (FGF21) and peroxisome proliferator-activated receptor gamma (PPARγ) that controlled EAT browning and participates the process of hyperglycemia-induced atrial fibrosis. Results In patients with DM and/or AF, serum hsa-miR-21-3p, instead of hsa-miR-21-5p, was significantly up-regulated. And miR-21 KO clearly ameliorated the atrial fibrosis in the diabetic mice. miR-21-3p as a key regulator that controls EAT browning and participates in atrial fibrosis under hyperglycemia conditions. Moreover, our gain- and loss-of-function experiments showed that FGFR1, as a direct target of miR-21-3p identified a regulatory pathway in EAT adipocytes consisting of miR-21-3p, FGFR1, FGF21 and PPARγ. Conclusions MiR-21-3p regulated EAT browning and participates the process of hyperglycemia-induced atrial fibrosis by targeting FGFR1/FGF21/PPARγ pathway.


2017 ◽  
Author(s):  
Elisa Holmlund-Suila ◽  
Maria Enlund-Cerullo ◽  
Saara Valkama ◽  
Helena Hauta-alus ◽  
Jenni Rosendahl ◽  
...  

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