Secretion Of Fibroblast Growth Factor Research Articles

Tumor-induced osteomalacia: a clinical case report

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome usually caused by small-sized tumors. Tumors secrete fibroblast growth factor 23 (FGF23), which has a phosphaturic effect. The clinical signs of TIO are non-specific, and include fatigue, bone pain and muscle weakness, which makes timely diagnosis of the disease difficult and treatment is often delayed.
 Well-timed diagnosis is essential and combined with complete tumor resection it leads to complete relief of symptoms and good postoperative prognosis. In cases of undetected tumors, medical treatment with phosphate supplements and active vitamin D medications is usually successful, however, treatment is associated with numerous complications and side effects can be burdensome for the patients. Due to the risk of recurrence or metastasis, patients with TIO require long-term management and follow-up.
 In this article, we present a clinical case of successful diagnosis and treatment of TIO in a young patient with type 1 diabetes mellitus.

MALAT1 overexpression promotes the proliferation of human periodontal ligament stem cells by upregulating fibroblast growth factor 2.

Fibroblast growth factor 2 (FGF2) has been revealed to promote human periodontal ligament stem cell (PDLSC) proliferation. The abnormal proliferation of PDLSCs has also been associated with the pathogenesis of periodontitis. The long non-coding RNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), has been demonstrated to regulate FGF2 secretion. Therefore, MALAT1 may also be associated with periodontitis. The aim of the present study was to investigate the effect of MALAT1 overexpression on the proliferation of PDLSCs. In the current study, PDLSCs derived from healthy and periodontitis-affected teeth were collected. MALAT1 and FGF2 mRNA expression in PDLSCs was detected using reverse transcription-quantitative PCR. PDLSCs overexpressing MALAT1 were subsequently generated. PDLSC proliferation was analyzed using a Cell Counting kit-8 assay. FGF2 protein expression was detected using western blot analysis. The results revealed that MALAT1 and FGF2 mRNA were significantly upregulated in PDLSCs derived from periodontitis-affected teeth when compared with PDLSCs derived from healthy teeth. PDLSCs derived from periodontitis-affected teeth also demonstrated a significantly higher proliferation rate than PDLSCs derived from healthy teeth. MALAT1 and FGF2 mRNA expression were positively correlated in both PDLSC groups. MALAT1 overexpression promoted the proliferation of healthy and periodontitis-affected PDLSC groups and upregulated FGF2 protein expression. The present study concluded that MALAT1 overexpression promoted the proliferation of human PDLSC potentially via upregulating FGF2.

Abstract LB-314: Fibroblast growth factor-2, derived from cancer-associated fibroblasts, stimulate proliferation and migration of human breast cancer cells though FGFR1

Abstract Cancer-associated fibroblasts (CAFs) constitute a major compartment of the tumor microenvironment. CAFs are distinct from normal fibroblasts for their overexpression of α-smooth muscle actin (α-SMA) and fibroblast activating protein. Recent studies suggest that CAFs play an important role in proliferation and migration of cancer cells through crosstalk with them. In the present study, we investigated the role for CAFs in breast cancer progression and underlying molecular mechanisms. We found the increased expression of α-SMA in human breast tumor tissues compared with normal adjacent tissues. In particular, α-SMA was highly expressed in the most of estrogen receptor (ER)-negative tumor tissues. When ER-negative breast cancer MDA-MB-231 cells and MDA-MB-468 cells were treated with the CAF-conditioned medium (CM), the cell viability was significantly elevated. In addition, MDA-MB-231 cells exhibited elevated expression of proliferative and invasive genes when incubated with CAFs. Notably, fibroblast growth factor-2 (FGF2) expression was correlated with the presence of CAFs. We noticed that mRNA level of FGF2 in CAFs as well as the concentration of FGF2 in CAF-CM was higher than that in normal fibroblasts. FGF2 exerts its biological effects by binding to FGF receptor 1 (FGFR1). In the breast cancer tissue microarray, 42% ER-negative patients co-expressed FGF2 and FGFR1 proteins, whereas only 19% ER-positive patients co-expressed those proteins. While the expression of FGFR1 was up-regulated in breast cancer cells, another major FGF2-corresponding receptor FGFR2 was barely expressed.This prompted us to explore FGF2-FGFR1 signaling in the context of paracrine communication. CAF-stimulated MDA-MB-231 cell migration and invasion as well as FGFR1 signaling activation were abolished when FGF2-neutralizing antibody was added to the CAF-CM. In a xenograft mouse model, co-injection of shmock-MDA-MB-231 cells with activated fibroblasts expressing FGF2 dramatically enhanced tumor growth, which suggests that stromal-derived FGF2 enhances tumor formation through activation of FGFR1 in cancer cells. Furthermore, FGF2 promotes nuclear localization of FGFR1 which might be associated with cancer cell proliferation and migration. In conclusion, secretion of FGF2 by CAFs stimulates proliferation and migration of breast cancer cells through interaction with FGFR1 which may contribute to human breast cancer progression. Citation Format: Jinyoung Suh, Do-Hee Kim, Hye-Kyung Na, Young-Joon Surh. Fibroblast growth factor-2, derived from cancer-associated fibroblasts, stimulate proliferation and migration of human breast cancer cells though FGFR1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-314.

2027-P: Dietary Cholesterol and Neuropeptide Agouti Related Peptide Act in Concert to Regulate Locomotor Activity

In an ever-changing environment where food availability is highly unpredictable, the ability to maintain energy homeostasis requires proper sensing of dietary macronutrients, and subsequent adaptive adjustments in feeding behavior. Cholesterol is an important macronutrient, but cytotoxic in excess. Thus, cholesterol metabolism is under tight homeostatic regulation. Cholesterol is a major precursor of bile acids. After a meal, bile acids are released into the intestine and stimulate the secretion of fibroblast growth factor 15/19 (FGF-15/19). FGF-15/19 is an enterokine known to specifically suppress Agouti-related protein (AgRP), a neuropeptide of the central melanocortin system (CMS) that increases with fasting and promotes feeding and locomotor activity. Studies show that the CMS plays a modulatory role in hepatic cholesterol metabolism. However, the effects of dietary cholesterol on feeding behavior and energy homeostasis have remained largely unexplored. In this study, we found, surprisingly, that dietary cholesterol modulates expression of AgRP. Specific removal of cholesterol from the diets of wild type mice under ad-lib conditions leads to increased hypothalamic Agrp, but not Npy, mRNA expression. Furthermore, these mice also have low intestinal fGF-15mRNA expression. Cholesterol deficiency also leads to increased locomotor activities, an effect that is AgRP dependent as locomotor activity in AgRP knockout mice is unaffected by alterations in dietary cholesterol content. In wild type mice, fasting induces increased locomotor activity, which is widely thought to be a proxy for food seeking behavior. Notably, we observe dietary cholesterol content has no effect on ad-libfood intake, suggesting food seeking behaviors may be uncoupled from food intake. Taken together, these results suggest a novel paradigm where dietary cholesterol can act as a peripheral nutrient signal that can ultimately affect locomotor activity and possibly food seeking behavior. Disclosure A. Huang: None. M.T. Maier: None. A. Xu: None.

Electrical stimulation facilitates the angiogenesis of human umbilical vein endothelial cells through MAPK/ERK signaling pathway by stimulating FGF2 secretion.

Electrical stimulation (ES) is able to enhance angiogenesis by stimulating fibroblasts. Fibroblast growth factor 2 (FGF2) is an independent angiogenesis inducer. The present study aimed to evaluate the role of ES-induced FGF2 secretion in affecting angiogenesis during wound healing via the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway. Fibroblasts and human umbilical vein endothelial cells (HUVECs) were exposed to ES, and the HUVECs were cocultured with ES-treated fibroblast culture solution. ES exposure showed no toxic effects on fibroblasts or HUVECs. ES led to enhanced growth of fibroblasts and HUVECs as well as FGF2 secretion, which is induced through the NOS pathway. ES-induced FGF2 secretion was shown to increase vascular endothelial growth factor (VEGF) protein and enhance migration, invasion, and angiogenesis of HUVECs. Also, ES-induced FGF2 secretion activated the MAPK/ERK signaling pathway. However, inhibition of the MAPK/ERK signaling pathway reversed the positive effects of ES-induced FGF2 secretion. In vitro experiments showed positive effects of ES on wound healing. Taken together, the findings suggested that ES promoted FGF2 secretion and then activated the MAPK/ERK signaling pathway by facilitating angiogenesis and promoting wound healing.

Candida albicans Morphology-Dependent Host FGF-2 Response as a Potential Therapeutic Target.

Angiogenesis mediated by proteins such as Fibroblast Growth Factor-2 (FGF-2) is a vital component of normal physiological processes and has also been implicated in contributing to the disease state associated with various microbial infections. Previous studies by our group and others have shown that Candida albicans, a common agent of candidiasis, induces FGF-2 secretion in vitro and angiogenesis in brains and kidneys during systemic infections. However, the underlying mechanism(s) via which the fungus increases FGF-2 production and the role(s) that FGF-2/angiogenesis plays in C. albicans disease remain unknown. Here we show, for the first time, that C. albicans hyphae (and not yeast cells) increase the FGF-2 response in human endothelial cells. Moreover, Candidalysin, a toxin secreted exclusively by C. albicans in the hyphal state, is required to induce this response. Our in vivo studies show that in the systemic C. albicans infection model, mice treated with FGF-2 exhibit significantly higher mortality rates when compared to untreated mice not given the angiogenic growth factor. Even treatment with fluconazole could not fully rescue infected animals that were administered FGF-2. Our data suggest that the increase of FGF-2 production/angiogenesis induced by Candidalysin contributes to the pathogenicity of C. albicans.

The association of indoxyl sulfate with fibroblast growth factor-23 in cats with chronic kidney disease.

BackgroundIndoxyl sulfate (IS) has been reported not only to increase with the severity of impaired renal function, but also possibly to be a factor associated with bone abnormalities linked to fibroblast growth factor‐23 (FGF‐23) in humans with chronic kidney disease (CKD). It is not yet known whether this correlation between IS and FGF‐23 holds true for cats with CKD.HypothesisAccumulation of IS is related to FGF‐23 secretion in cats with CKD.AnimalsTwenty clinically healthy cats and 73 cats with CKD cases were evaluated retrospectively.MethodsThe concentrations of IS and FGF‐23 in plasma were determined by high‐performance liquid chromatography and ELISA, respectively. Progression was defined as an increment of 0.5 mg/dL of serum creatinine concentration within 3 months.ResultsPlasma IS and FGF‐23 concentrations were significantly increased concurrently with decreasing renal function. Higher concentration of FGF‐23 was significantly associated with higher concentration of IS after adjusting for various confounding factors including creatinine and phosphate. Furthermore, the correlation between IS and phosphate was higher than that between FGF‐23 and phosphate. When the renal progression group was compared with the non‐progression group, both IS and FGF‐23 were found to be significantly increased (P < .05). In addition, the area under receiver operator curve of the combination of IS and FGF‐23 predicted renal progression at a level >0.9.Conclusions and Clinical ImportanceBoth FGF‐23 and IS are associated with phosphate metabolism and CKD progression.

Fibroblast Growth Factor 2 Enhances Zika Virus Infection in Human Fetal Brain.

Zika virus (ZIKV) is an emerging pathogen that can cause microcephaly and other neurological defects in developing fetuses. The cellular response to ZIKV in the fetal brain is not well understood. Here, we show that ZIKV infection of human fetal astrocytes (HFAs), the most abundant cell type in the brain, results in elevated expression and secretion of fibroblast growth factor 2 (FGF2). This cytokine was shown to enhance replication and spread of ZIKV in HFAs and human fetal brain explants. The proviral effect of FGF2 is likely mediated in part by suppression of the interferon response, which would represent a novel mechanism by which viruses antagonize host antiviral defenses. We posit that FGF2-enhanced virus replication in the fetal brain contributes to the neurodevelopmental disorders associated with in utero ZIKV infection. As such, targeting FGF2-dependent signaling should be explored further as a strategy to limit replication of ZIKV.

Regulation of α-Klotho Expression by Dietary Phosphate During Growth Periods.

Inorganic phosphate (Pi) is an essential nutrient for maintaining various biological functions, particularly during growth periods. Excess intake of dietary Pi increases the secretion of fibroblast growth factor 23 (FGF23) and parathyroid hormone to maintain plasma Pi levels. FGF23 is a potent phosphaturic factor that binds to the α-klotho/FGFR complex in the kidney to promote excretion of Pi into the urine. In addition, excess intake of dietary Pi decreases renal α-klotho expression. Down-regulation or lack of α-klotho induces a premature aging-like phenotype, resulting from hyperphosphatemia, and leading to conditions such as ectopic calcification and osteoporosis. However, it remains unclear what effects dietary Pi has on α-klotho expression at different life stages, especially during growth periods. To investigate this, we used C57BL/6J mice in two life stages during growing period. Weaned (3 weeks old) and periadolescent (7 weeks old) were randomly divided into seven experimental groups and fed with 0.02, 0.3, 0.6, 0.9, 1.2, 1.5, or 1.8% Pi diets for 7days. As a result, elevated plasma Pi and FGF23 levels and decreased renal α-klotho expression were observed in weaned mice fed with a high Pi diet. In addition, a high Pi diet clearly induced renal calcification in the weaned mice. However, in the periadolescent group, renal calcification was not observed, even in the 1.8% Pi diet group. The present study indicates that a high Pi diet in weaned mice has much greater adverse effects on renal α-klotho expression and pathogenesis of renal calcification compared with periadolescent mice.

Obesity in Adolescents and Youth: The Case for and against Bariatric Surgery

Obesity in Adolescents and Youth: The Case for and against Bariatric Surgery

Glucagon-Like Peptide 1 Increases β-Cell Regeneration by Promoting α- to β-Cell Transdifferentiation.

Glucagon-like peptide 1 (GLP-1) can increase pancreatic β-cells, and α-cells could be a source for new β-cell generation. We investigated whether GLP-1 increases β-cells through α-cell transdifferentiation. New β-cells originating from non-β-cells were significantly increased in recombinant adenovirus expressing GLP-1 (rAd-GLP-1)-treated RIP-CreER;R26-YFP mice. Proliferating α-cells were increased in islets of rAd-GLP-1-treated mice and αTC1 clone 9 (αTC1-9) cells treated with exendin-4, a GLP-1 receptor agonist. Insulin+glucagon+ cells were significantly increased by rAd-GLP-1 or exendin-4 treatment in vivo and in vitro. Lineage tracing to label the glucagon-producing α-cells showed a higher proportion of regenerated β-cells from α-cells in rAd-GLP-1-treated Glucagon-rtTA;Tet-O-Cre;R26-YFP mice than rAd producing β-galactosidase-treated mice. In addition, exendin-4 increased the expression and secretion of fibroblast growth factor 21 (FGF21) in αTC1-9 cells and β-cell-ablated islets. FGF21 treatment of β-cell-ablated islets increased the expression of pancreatic and duodenal homeobox-1 and neurogenin-3 and significantly increased insulin+glucagon+ cells. Generation of insulin+glucagon+ cells by exendin-4 was significantly reduced in islets transfected with FGF21 small interfering RNA or islets of FGF21 knockout mice. Generation of insulin+ cells by rAd-GLP-1 treatment was significantly reduced in FGF21 knockout mice compared with wild-type mice. We suggest that GLP-1 has an important role in α-cell transdifferentiation to generate new β-cells, which might be mediated, in part, by FGF21 induction.

Os et métabolisme

Bone is now considered as a particular endocrine organ. Its endocrine function is not yet fully understood and has been the subject of several conferences at the European Society of Endocrinology Congress 2018. Bone regulates phosphate metabolism by secreting fibroblast growth factor 23; it also regulates glucose metabolism via osteocalcin and energy metabolism, thanks to lipocalin 2, a new hormone acting on the brain.In addition, the incidence of diabetes continues to grow, and its impact on bone has been demonstrated, with an increased risk of fractures regardless the type of diabetes. The mechanism of bone fragility in this disease is not fully known but it involves a decrease in bone turnover and bone demineralization.Recent findings on the role of bone on glucose and mineral metabolism could open therapeutic perspectives, especially for the treatment of diabetes or obesity.

The interrelation between FGF23 and glucose metabolism in humans

AimsDifferent studies point to a link between glucose metabolism and Fibroblast Growth Factor 23 (FGF23), an osteocyte-derived phosphaturic hormone. We aimed to investigate in humans the effect of (I) a glucose load and (II) a hyperinsulinemic-euglycemic clamp on FGF23 concentrations and conversely (III) the effect of a diet-induced increase in FGF23 concentration on glucose and insulin concentrations. MethodsPlasma cFGF23 concentrations were measured during: I. an oral glucose tolerance test in eight adults with impaired glucose tolerance and vitamin D deficiency and II. a hyperinsulinemic-euglycemic clamp in nine healthy adults. III. Serum glucose and insulin concentrations were measured in nine healthy adults receiving a single-day phosphate-enriched or -restricted diet. ResultsI. A glucose load decreased FGF23 and phosphate concentrations. II. The hyperinsulinemic-euglycemic clamp decreased phosphate concentrations, but did not affect FGF23 concentrations. III. Fasting insulin and glucose concentrations remained unchanged after a diet-induced increase in FGF23 concentration. ConclusionsAn oral glucose load in vitamin D deficient patients with impaired glucose metabolism decreased FGF23 concentrations, which cannot be attributed to changes in insulin concentration. Thus, bone may react rapidly after glucose loading by alternating FGF23 secretion. A diet-induced increase in FGF23 concentrations did not affect fasting glucose or insulin levels.

Augmented Fibroblast Growth Factor-23 Secretion in Bone Locally Contributes to Impaired Bone Mineralization in Chronic Kidney Disease in Mice.

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a systemic disorder of mineral and bone metabolism caused by CKD. Impaired bone mineralization together with increased bony secretion of fibroblast growth factor-23 (FGF23) are hallmarks of CKD-MBD. We recently showed that FGF23 suppresses the expression of tissue nonspecific alkaline phosphatase (TNAP) in bone cells by a Klotho-independent, FGF receptor-3-mediated signaling axis, leading to the accumulation of the mineralization inhibitor pyrophosphate. Therefore, we hypothesized that excessive FGF23 secretion may locally impair bone mineralization in CKD-MBD. To test this hypothesis, we induced CKD by 5/6 nephrectomy in 3-month-old wild-type (WT) mice and Fgf23−/−/VDRΔ/Δ (Fgf23/VDR) compound mutant mice maintained on a diet enriched with calcium, phosphate, and lactose. Eight weeks postsurgery, WT CKD mice were characterized by reduced bone mineral density at the axial and appendicular skeleton, hyperphosphatemia, secondary hyperparathyroidism, increased serum intact Fgf23, and impaired bone mineralization as evidenced by bone histomorphometry. Laser capture microdissection in bone cryosections showed that both osteoblasts and osteocytes contributed to the CKD-induced increase in Fgf23 mRNA abundance. In line with our hypothesis, osteoblastic and osteocytic activity of alkaline phosphatase was reduced, and bone pyrophosphate concentration was ~2.5-fold higher in CKD mice, relative to Sham controls. In Fgf23/VDR compound mice lacking Fgf23, 5/6-Nx induced secondary hyperparathyroidism and bone loss. However, 5/6-Nx failed to suppress TNAP activity, and bone pyrophosphate concentrations remained unchanged in Fgf23/VDR CKD mice. Collectively, our data suggest that elevated Fgf23 production in bone contributes to the mineralization defect in CKD-MBD by auto-/paracrine suppression of TNAP and subsequent accumulation of pyrophosphate in bone. Hence, our study has identified a novel mechanism involved in the pathogenesis of CKD-MBD.

Burosumab Therapy in Children with X-Linked Hypophosphatemia

BackgroundX-linked hypophosphatemia is characterized by increased secretion of fibroblast growth factor 23 (FGF-23), which leads to hypophosphatemia and consequently rickets, osteomalacia, and skeletal deformities. We investigated burosumab, a monoclonal antibody that targets FGF-23, in patients with X-linked hypophosphatemia.MethodsIn an open-label, phase 2 trial, we randomly assigned 52 children with X-linked hypophosphatemia, in a 1:1 ratio, to receive subcutaneous burosumab either every 2 weeks or every 4 weeks; the dose was adjusted to achieve a serum phosphorus level at the low end of the normal range. The primary end point was the change from baseline to weeks 40 and 64 in the Thacher rickets severity total score (ranging from 0 to 10, with higher scores indicating greater disease severity). In addition, the Radiographic Global Impression of Change was used to evaluate rachitic changes from baseline to week 40 and to week 64. Additional end points were changes in pharmacodynamic markers, linear growth, physical ability, and patient-reported outcomes and the incidence of adverse events.ResultsThe mean Thacher rickets severity total score decreased from 1.9 at baseline to 0.8 at week 40 with every-2-week dosing and from 1.7 at baseline to 1.1 at week 40 with every-4-week dosing (P<0.001 for both comparisons); these improvements persisted at week 64. The mean serum phosphorus level increased after the first dose in both groups, and more than half the patients in both groups had levels within the normal range (3.2 to 6.1 mg per deciliter [1.0 to 2.0 mmol per liter]) by week 6. Stable serum phosphorus levels were maintained through week 64 with every-2-week dosing. Renal tubular phosphate reabsorption increased from baseline in both groups, with an overall mean increase of 0.98 mg per deciliter (0.32 mmol per liter). The mean dose of burosumab at week 40 was 0.98 mg per kilogram of body weight with every-2-week dosing and 1.50 mg per kilogram with every-4-week dosing. Across both groups, the mean serum alkaline phosphatase level decreased from 459 U per liter at baseline to 369 U per liter at week 64. The mean standing-height z score increased in both groups, with greater improvement seen at all time points with every-2-week dosing (an increase from baseline of 0.19 at week 64) than with every-4-week dosing (an increase from baseline of 0.12 at week 64). Physical ability improved and pain decreased. Nearly all the adverse events were mild or moderate in severity.ConclusionsIn children with X-linked hypophosphatemia, treatment with burosumab improved renal tubular phosphate reabsorption, serum phosphorus levels, linear growth, and physical function and reduced pain and the severity of rickets. (Funded by Ultragenyx Pharmaceutical and Kyowa Hakko Kirin; ClinicalTrials.gov number, NCT02163577; EudraCT number, 2014-000406-35).

Comment on Chan et al. FGF23 Concentration and APOL1 Genotype Are Novel Predictors of Mortality in African Americans With Type 2 Diabetes. Diabetes Care 2018;41:178–186

We read with great interest the article by Chan et al. (1) demonstrating that fibroblast growth factor 23 (FGF23) concentration is a novel predictor of mortality in African Americans with type 2 diabetes. FGF23 is the main hormone mediating serum phosphorus concentration through inhibiting tubular reabsorption of phosphorus from the urine (2). Meanwhile, serum phosphorus is the main stimulus for FGF23 secretion. In progressive chronic kidney disease …

Biological and Clinical Effects of Calciprotein Particles on Chronic Kidney Disease-Mineral and Bone Disorder.

Calciprotein particles (CPPs) are a new biological marker of chronic kidney disease-mineral and bone disorder (CKD-MBD). CPPs consist of phosphate, calcium, and some proteins, with phosphate being the major contributor to the level and biological activity of CPPs. Recent studies have shown the physiological and pathological significance of CPPs, including contributions to bone and mineral metabolism, and to tissue and organ impairments such as cardiovascular damage and inflammatory responses. These actions are well known as important aspects of CKD-MBD. Fibroblast growth factor 23 (FGF23), which is secreted from the bone as the phosphaturic hormone, is markedly elevated in CKD-MBD. Many clinical studies have shown significant relationships between the level of FGF23 and outcomes such as mortality, prevalence of cardiovascular disease, bone fracture, and levels of inflammatory markers. Basic and clinical studies have suggested that CPPs contribute to synthesis and secretion of FGF23. Surgical treatments such as renal transplantation and parathyroidectomy for patients with CKD-MBD suppress excess levels of phosphate, calcium, parathyroid hormone (PTH), and FGF23, which are related to the CPP level. Therefore, suppression of CPPs might also contribute to improved clinical outcomes after these treatments.

Bone and calcium metabolism associated with malignancy. Tumor-induced osteomalacia.

Tumor-induced osteomalacia(TIO)is a paraneoplastic syndrome caused by excessive production and secretion of fibroblast growth factor 23(FGF23)from causative tumors which induces hypophosphatemia and osteomalacia. Mesenchymal benign tumors in bone or soft tissue are the most frequent causes for TIO. The first choice treatment of TIO is complete resection of the responsible tumors. In patients whose tumors cannot be completely removed, phosphate salt and active vitamin D are usually prescribed. The effect of anti-FGF23 monoclonal antibody that inhibits the actions of FGF23 is being tested in clinical trials.

Generation of Isthmic Organizer-Like Cells from Human Embryonic Stem Cells.

The objective of this study was to induce the production of isthmic organizer (IsO)-like cells capable of secreting fibroblast growth factor (FGF) 8 and WNT1 from human embryonic stem cells (ESCs). The precise modulation of canonical Wnt signaling was achieved in the presence of the small molecule CHIR99021 (0.6 μM) during the neural induction of human ESCs, resulting in the differentiation of these cells into IsO-like cells having a midbrain-hindbrain border (MHB) fate in a manner that recapitulated their developmental course in vivo. Resultant cells showed upregulated expression levels of FGF8 and WNT1. The addition of exogenous FGF8 further increased WNT1 expression by 2.6 fold. Gene ontology following microarray analysis confirmed that IsO-like cells enriched the expression of MHB-related genes by 40 fold compared to control cells. Lysates and conditioned media of IsO-like cells contained functional FGF8 and WNT1 proteins that could induce MHB-related genes in differentiating ESCs. The method for generating functional IsO-like cells described in this study could be used to study human central nervous system development and congenital malformations of the midbrain and hindbrain.

Perilipin 5 Deletion Unmasks an Endoplasmic Reticulum Stress-Fibroblast Growth Factor 21 Axis in Skeletal Muscle.

Lipid droplets (LDs) are critical for the regulation of lipid metabolism, and dysregulated lipid metabolism contributes to the pathogenesis of several diseases, including type 2 diabetes. We generated mice with muscle-specific deletion of the LD-associated protein perilipin 5 (PLIN5, Plin5MKO ) and investigated PLIN5's role in regulating skeletal muscle lipid metabolism, intracellular signaling, and whole-body metabolic homeostasis. High-fat feeding induced changes in muscle lipid metabolism of Plin5MKO mice, which included increased fatty acid oxidation and oxidative stress but, surprisingly, a reduction in inflammation and endoplasmic reticulum (ER) stress. These muscle-specific effects were accompanied by whole-body glucose intolerance, adipose tissue insulin resistance, and reduced circulating insulin and C-peptide levels in Plin5MKO mice. This coincided with reduced secretion of fibroblast growth factor 21 (FGF21) from skeletal muscle and liver, resulting in reduced circulating FGF21. Intriguingly, muscle-secreted factors from Plin5MKO , but not wild-type mice, reduced hepatocyte FGF21 secretion. Exogenous correction of FGF21 levels restored glycemic control and insulin secretion in Plin5MKO mice. These results show that changes in lipid metabolism resulting from PLIN5 deletion reduce ER stress in muscle, decrease FGF21 production by muscle and liver, and impair glycemic control. Further, these studies highlight the importance for muscle-liver cross talk in metabolic regulation.