FGF Receptor Research Articles

Nuclear Localization of Fibroblast Growth Factor Receptor 1 in Breast Cancer Cells Interacting with Cancer Associated Fibroblasts.

Cancer-associated fibroblasts (CAFs) represent a major component of the tumor microenvironment and interplay with cancer cells by secreting cytokines, growth factors and extracellular matrix proteins. When estrogen receptor-negative breast cancer MDA-MB-231 cells were treated with the CAF-conditioned medium (CAF-CM), Akt and STAT3 involved in cell proliferation and survival were activated through phosphorylation. CAFs secrete fibroblast growth factor 2 (FGF2), thereby stimulating breast cancer cell progression. Akt activation induced by CAF-CM in MDA-MB-231 cells was abolished when FGF2-neutralizing antibody was added. Treatment of MDA-MB-231 cells directly with FGF2 enhanced the phosphorylation of Akt and the FGF receptor (FGFR) substrate, FRS2α. These events were abrogated by siRNA-mediated silencing of FGFR1. In a xenograft mouse model, co-injection of MDA-MB-231 cells with activated fibroblasts expressing FGF2 dramatically enhanced activation of Akt. Stable knockdown of FGFR1 blunted Akt phosphorylation in xenograft tumors. MDA-MB-231 cells co-cultured with CAFs or directly stimulated with FGF2 exhibited enhanced nuclear localization of FGFR1. Notably, FGF2 stimulation produced reactive oxygen species (ROS) accumulation in MDA-MB-231 cells, and FGF2-induced nuclear accumulation of FGFR1 was abrogated by the ROS scavenging agent, N-acetylcysteine.

Suppression of Cutibacterium acnes-Mediated Inflammatory Reactions by Fibroblast Growth Factor 21 in Skin.

Cutibacterium acnes (C. acnes) is a common commensal bacterium that is closely associated with the pathogenesis of acne. Fibroblast growth factor 21 (FGF21), as a favorable regulator of glucose and lipid metabolism and insulin sensitivity, was recently shown to exert anti-inflammatory effects. The role and mechanism of FGF21 in the inflammatory reactions induced by C. acnes, however, have not been determined. The present study shows that FGF21 in the dermis inhibits epidermal C. acnes-induced inflammation in a paracrine manner while it functions on the epidermal layer through a receptor complex consisting of FGF receptor 1 (FGFR1) and β-Klotho (KLB). The effects of FGF21 in heat-killed C. acnes-induced HaCaT cells and living C. acnes-injected mouse ears were examined. In the presence of C. acnes, FGF21 largely counteracted the activation of Toll-like receptor 2 (TLR2), the downstream nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPK) signaling pathways induced by C. acnes. FGF21 also significantly reduced the expression of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α. Taken together, these findings indicate that FGF21 suppresses C. acnes-induced inflammation and might be used clinically in the management and treatment of acne.

The FGF receptor inhibitor PD173074 modulates Lefty expression in human induced pluripotent stem cells differently depending on the culture conditions

The FGF receptor inhibitor PD173074 modulates Lefty expression in human induced pluripotent stem cells differently depending on the culture conditions

FGF4 protects the liver from nonalcoholic fatty liver disease by activating the AMP-activated protein kinase-Caspase 6 signal axis.

NAFLD represents an increasing health problem in association with obesity and diabetes with no effective pharmacotherapies. Growing evidence suggests that several FGFs play important roles in diverse aspects of liver pathophysiology. Here, we report a previously unappreciated role of FGF4 in the liver. Expression of hepatic FGF4 is inversely associated with NAFLD pathological grades in both human patients and mouse models. Loss of hepatic Fgf4 aggravates hepatic steatosis and liver damage resulted from an obesogenic high-fat diet. By contrast, pharmacological administration of recombinant FGF4 mitigates hepatic steatosis, inflammation, liver damage, and fibrogenic markers in mouse livers induced to develop NAFLD and NASH under dietary challenges. Such beneficial effects of FGF4 are mediated predominantly by activating hepatic FGF receptor (FGFR) 4, which activates a downstream Ca2+ -Ca2+ /calmodulin-dependent protein kinase kinase beta-dependent AMP-activated protein kinase (AMPK)-Caspase 6 signal axis, leading to enhanced fatty acid oxidation, reduced hepatocellular apoptosis, and mitigation of liver damage. Our study identifies FGF4 as a stress-responsive regulator of liver pathophysiology that acts through an FGFR4-AMPK-Caspase 6 signal pathway, shedding light on strategies for treating NAFLD and associated liver pathologies.

Updated results of the phase II ALTER-H003 trial: Anlotinib plus toripalimab as a first-line treatment for patients with unresectable hepatocellular carcinoma.

446 Background: The combination therapies of anti-angiogenic with anti-PD-1/L1 agents have shown superior efficacy over sorafenib in the first-line treatment for uHCC. Anlotinib, a multi-targeted tyrosine kinase inhibitor that targets VEGF receptors 1/2/3, FGF receptors 1-4, PDGF receptors α and β, and c-kit, is approved for treatment of several malignancies in China. Toripalimab is a humanized lgG4 mAb against PD-1. Preliminary results demonstrated good efficacy and tolerable safety of the combined regimen. Here we updated the results with more enrolled patients and longer follow-up duration. Methods: This single arm, multicenter, phase II trial of ALTER-H003 was planned to enroll 30 pts without prior systemic treatment to receive anlotinib (12 mg, p.o., qd, d1-14, q3w) and toripalimab (240 mg, iv, d1, q3w) until disease progression or unacceptable toxicity. Primary endpoint was ORR according to mRECIST and irRECIST. Secondary endpoints included PFS, OS, DCR, DoR and safety. Results: By the cutoff date of September 18, 2021, 31 pts were enrolled and treatment duration ranged from 0.23+ to 14.65+ months. Among 26 evaluable pts, the confirmed ORR and DCR according to mRECIST was 34.6% (95% Cl 17.2%-55.7%) and 92.3% (95% Cl 17.2%-55.7%), respectively. The DoRs ranged from 1.38 month to 9.69 month. The preliminary median PFS was 10.2m (95% Cl 6.1-14.3) and the median OS have not reached yet. 28 of 31 pts (90.3%) occurred treatment-related adverse events (TRAEs). Grade 3-5 TRAEs were recorded in 14 pts (45.2%). Immune-Related TRAEs (irTRAEs) occurred in 21 pts (67.7%), while 5 patients (16.1%) had grade 3-5 irTRAEs. The most common grade 3 TRAEs included hypertension (n = 3, 9.7%), hand-foot skin reaction (n = 2, 6.5%), arthralgia (n = 2, 6.5%), total bilirubin increased(n = 2, 6.5%) and fatigue (n = 2, 6.5%). The grade 3 irTRAEs were total bilirubin increased (n = 2, 6.5%), AST increased (n = 1, 3.2%), fever (n = 1, 3.2%), arthralgia (n = 1, 3.2%) and fatigue (n = 1, 3.2%). No grade 4 TRAEs occurred.1 patient had an irTRAE that led to death (immune-related pneumonitis). Conclusions: This combination therapy of anlotinib plus toripalimab in the first-line treatment for uHCC yielded satisfactory anti-tumor efficacy and manageable toxicity. The study is still ongoing and detailed data will be presented. Clinical trial information: ChiCTR1900028295.

Anlotinib combined with mXELIRI as second-line treatment in advanced colorectal cancer pretreated with bevacizumab plus standard chemotherapy: A single-arm, phase IB/II study.

TPS220 Background: For advanced colorectal cancer (CRC), fluoropyrimidine-based chemotherapy (5-FU or capecitabine combined with oxaliplatin) with VEGF inhibitors (bevacizumab) is standard first-line treatment. However, once this treatment had been used, the second line treatment is limited. Although continuation of bevacizumab after first progression can improve PFS and OS, the benefit of bevacizumab may be reduced compared with who never pre-treated with bevacizumab (the ML18147 study). Anlotinib is an oral small molecule tyrosine kinases inhibitor, targeting VEGF receptors 1/2/3, FGF receptors 1-4, PDGF receptors α/β and c-kit. mXELIRI is a chemotherapy regimen consisting of irinotecan and capecitabine. The trial is to investigate the efficacy and safety of anlotinib combined with mXELIRI as second-line treatment in advanced colorectal cancer pre-treated with bevacizumab plus standard chemotherapy. Methods: This is a multi-center, prospective, single-arm, 2-part, phase Ib/II study. Eligible pts are aged 18-75 years with histologically and radiographically confirmed mCRC who had progressed or intolerant with bevacizumab plus FOLFOX or CAPEOX regimen chemotherapy treatment. ECOG performance status 0 - 1, and adequate organ function. Treatment: anlotinib (8mg, 10mg or 12mg), po, qd, on days 1-14 every 3 weeks; irinotecan 180-200 mg/m2, iv, on day 1 every 3 weeks; capecitabine, 800 mg/m2, po, bid, on days 1-14 every 3 weeks. For the phase 1b segment, a standard 3+3 dose-escalation design is used to determine the maximum tolerated dose or recommended phase 2 dose (RP2D) of anlotinib. 3 patients are enrolled and treated per dose level (8mg,10mg,12mg). If no DLT, dose is escalated for the next cohort of 3 patients; If 1 DLT, 3 additional patients are treated at this level with dose escalation only if no additional DLTs；If ≥ 2 DLTs, prior dose level is defined as MTD. MTD decided when 6 patients are treated at a dose level with < 2 DLTs. Primary endpoint is objective response rate (ORR) according to RECIST v1.1. Secondary endpoints are progression-free survival (PFS), overall survival (OS), disease control rate (DCR), duration of response (DOR) and quality of life (QoL). Based on a one-sided one sample log-rank test with 2.5% Type I error, 80% power to detect an improvement in ORR from 5.4% to 15%, there will be 94 patients consider 20% of patients fall off. Research Sponsor: Guangdong Provincial Hospital of Chinese Medicine Clinical trial information: NCT05035914.

Synthesis, spectral characterization and biological activities of Ag(I), Pt(IV) and Au(III) complexes with novel azo dye ligand (N, N, O) derived from 2-amino-6-methoxy benzothiazole

The novel ligand 2-[2'-(6-methoxybenzothiazolyl)azo]-3,5-dimethyl benzoic acid (6-MBTAMB), derived from 2-amino-6-methoxy benzothiazole, has been used to synthesize a series of new metal complexes of Ag(I), Pt(IV) and Au(III). The metal complexes were characterized by elemental analyses (CHNS), molar conductivity, crystal structure (XRD), spectroscopic techniques: FT-IR, 1H NMR, 13C NMR, UV–Vis, mass spectra, thermal analysis (TG–DTA), FE-SEM and magnetic properties. Results confirmed that the azo dye ligand behaves a tridentate and coordinates to the metal ion via nitrogen atom of azomethine group of heterocyclic benzothiazole ring, nitrogen atom of the azo group which is the farthest of the benzothiazole molecule and carboxylic oxygen. Antimicrobial properties of all newly synthesized azo compounds are also demonstrated against bacterial pathogenic organisms and fungi. These complexes are more effective against bacteria and less effective against fungi compared to standard antibacterial drugs (novobiocin) and antifungal drugs (cycloheximide). By using the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging test, it was discovered that the complexes had good antioxidant properties. In addition, the (6-MBTAMB) and metal complexes were docked with the crystal structure of FGF Receptor 2 (FGFR2) kinase domain harboring the pathogenic gain of function K659E mutation identified in endometrial cancer using the molecular operating environment (MOE) module. In vitro studies on human endometrial cancer cell lines (MFE-296) as well as healthy human umbilical vein endothelial cells (HUVEC) show uptake of the intact compounds by the cancer cells and increased activity against the cancer cells.Graphical abstract

Fibroblast growth factor 10 attenuates chronic obstructive pulmonary disease by protecting against glycocalyx impairment and endothelial apoptosis

BackgroundThe defects and imbalance in lung repair and structural maintenance contribute to the pathogenesis of chronic obstructive pulmonary diseases (COPD), yet the molecular mechanisms that regulate lung repair process are so far incompletely understood. We hypothesized that cigarette smoking causes glycocalyx impairment and endothelial apoptosis in COPD, which could be repaired by the stimulation of fibroblast growth factor 10 (FGF10)/FGF receptor 1 (FGFR1) signaling.MethodsWe used immunostaining (immunohistochemical [IHC] and immunofluorescence [IF]) and enzyme-linked immunosorbent assay (ELISA) to detect the levels of glycocalyx components and endothelial apoptosis in animal models and in patients with COPD. We used the murine emphysema model and in vitro studies to determine the protective and reparative role of FGF10/FGFR1.ResultsExposure to cigarette smoke caused endothelial glycocalyx impairment and emphysematous changes in murine models and human specimens. Pretreatment of FGF10 attenuated the development of emphysema and the shedding of glycocalyx components induced by CSE in vivo. However, FGF10 did not attenuate the emphysema induced by endothelial-specific killing peptide CGSPGWVRC-GG-D(KLAKLAK)2. Mechanistically, FGF10 alleviated smoke-induced endothelial apoptosis and glycocalyx repair through FGFR1/ERK/SOX9/HS6ST1 signaling in vitro. FGF10 was shown to repair pulmonary glycocalyx injury and endothelial apoptosis, and attenuate smoke-induced COPD through FGFR1 signaling.ConclusionsOur results suggest that FGF10 may serve as a potential therapeutic strategy against COPD via endothelial repair and glycocalyx reconstitution.

Prazosin improves neurogenic acute heart failure through downregulation of fibroblast growth factor 23 in rat hearts.

Bilateral nucleus tractus solitarii (NTS) lesions, possibly caused by enterovirus 71 infection, cause severe neurogenic hypertension, leading to acute heart failure (HF), pulmonary edema, and death within hours. Alpha-adrenergic blockers attenuate blood pressure and ameliorate HF and pulmonary edema, thereby prolonging survival time. However, the molecular mechanisms of these blockers are not clear. In this study, we investigated these mechanisms in a rat model of 6-hydroxydopamine (6-OHDA)-induced HF. Sprague-Dawley rats were treated with prazosin 10 min after the microinjection of 6-OHDA into the NTS. Immunohistochemistry and dihydroethidium (DHE) staining were used for analysis. In the cardiac tissue of 6-OHDA-induced HF, in situ expression of tumor necrosis factor-alpha (TNF-α), fibroblast growth factor-23 (FGF23), and FGF receptor 1 (FGFR1) increased, but in situ expression of Vitamin D receptor (VDR) decreased. DHE staining revealed several heart cells with high reactive oxygen species production. Prazosin treatment decreased TNF-α, FGF23, and FGFR1 expression in the heart of rats with 6-OHDA-induced HF. It also prevented cardiomyopathy caused by 6-OHDA-induced bilateral NTS lesions by inhibiting the FGF23-FGFR1 pathway and downregulating TNF-α expression. In situ, FGF23, FGFR1, VDR, superoxide, and TNF-α in the heart were found to be involved in acute HF in our rat model of 6-OHDA-induced bilateral NTS lesions. These findings are potentially useful for treating fatal enterovirus 71 infection-induced NTS lesions and HF.

Dietary acetic acid suppress high-fat diet-induced obesity in mice by altering taurine conjugated bile acids metabolism

Vinegar is widely used in Chinese diet as a traditional condiment, and its functional component acetic acid has been proposed to prevent obesity, while its mechanism is still unclear. Bile acids (BAs) have been reported to have a protective effect on obesity. This study demonstrated that high-fat diet induced obesity (DIO) seriously disturbed BAs balance by significantly decreasing hepatic BAs synthesis and increasing fecal BAs excretion. However, acetate supplemented in the high-fat diet can restore BAs balance by mainly promoting hepatic taurine conjugated BAs (tauro-BAs) synthesis and decreasing fecal tauro-BAs excretion. The tauro-BAs, as the antagonists, inhibited the intestinal-liver farnesoid X receptor (FXR)-fibroblast growth factor 15 (FGF15)-FGF receptor 4 (FGFR4) signaling pathway, and negatively regulated the production of hepatic BAs. Present study provided important clues for further investigation of the mechanism of acetic acid inhibiting DIO.

FGF1 and insulin control lipolysis by convergent pathways

Inexorable increases in insulin resistance, lipolysis, and hepatic glucose production (HGP) are hallmarks of type 2 diabetes. Previously, we showed that peripheral delivery of exogenous fibroblast growth factor 1 (FGF1) has robust anti-diabetic effects mediated by the adipose FGF receptor (FGFR) 1. However, its mechanism of action is not known. Here, we report that FGF1 acutely lowers HGP by suppressing adipose lipolysis. On a molecular level, FGF1 inhibits the cAMP-protein kinase A axis by activating phosphodiesterase 4D (PDE4D), which separates it mechanistically from the inhibitory actions of insulin via PDE3B. We identify Ser44 as an FGF1-induced regulatory phosphorylation site in PDE4D that is modulated by the feed-fast cycle. These findings establish the FGF1/PDE4 pathway as an alternate regulator of the adipose-HGP axis and identify FGF1 as an unrecognized regulator of fatty acid homeostasis.

Advances in understanding of phosphate homeostasis and related disorders.

Inorganic phosphate (Pi) in the mammalian body is balanced by its influx and efflux through the intestines, kidneys, bones, and soft tissues, at which several sodium/Pi co-transporters mediate its active transport. Pi homeostasis is achieved through the complex counter-regulatory feedback balance between fibroblast growth factor 23 (FGF23), 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone. FGF23, which is mainly produced by osteocytes in bone, plays a central role in Pi homeostasis and exerts its effects by binding to the FGF receptor (FGFR) and αKlotho in distant target organs. In the kidneys, the main target, FGF23 promotes the excretion of Pi and suppresses the production of 1,25(OH)2D. Deficient and excess FGF23 result in hyperphosphatemia and hypophosphatemia, respectively. FGF23-related hypophosphatemic rickets/osteomalacia include tumor-induced osteomalacia and various genetic diseases, such as X-linked hypophosphatemic rickets. Coverage by the national health insurance system in Japan for the measurement of FGF23 and the approval of burosumab, an FGF23-neutralizing antibody, have had a significant impact on the diagnosis and treatment of FGF23-related hypophosphatemic rickets/osteomalacia. Some of the molecules responsible for genetic hypophosphatemic rickets/osteomalacia are highly expressed in osteocytes and function as local regulators of FGF23 production. A number of systemic factors also regulate FGF23 levels. Although the mechanisms responsible for Pi sensing in mammals have not yet been elucidated in detail, recent studies have suggested the involvement of FGFR1. The further clarification of the mechanisms by which osteocytes detect Pi levels and regulate FGF23 production will lead to the development of better strategies to treat hyperphosphatemic and hypophosphatemic conditions.

Intracellular FGF1 Promotes Invasion and Migration in Thyroid Carcinoma Via HMGA1 Independent of FGF Receptors

Intracellular FGF1 Promotes Invasion and Migration in Thyroid Carcinoma Via HMGA1 Independent of FGF Receptors

Phosphate-Sensing.

The blood level of phosphate is tightly regulated in a narrow range. Hyperphosphatemia and hypophosphatemia both lead to the development of diseases, such as hyperphosphatemic tumoral calcinosis and rickets/osteomalacia, respectively. Although several humoral factors have been known to affect blood phosphate levels, fibroblast growth factor 23 (FGF23) is the principal hormone involved in the regulation of blood phosphate. This hormone is produced by bone, particularly by osteocytes and osteoblasts, and has the effect of lowering the blood level of phosphate in the renal proximal tubules. Therefore, some phosphate-sensing mechanism should exist, at least in the bone. However, the mechanisms through which bone senses changes in the blood level of phosphate, and through which the bone regulates FGF23 production remain to be fully elucidated. Our recent findings demonstrate that high extracellular phosphate phosphorylates FGF receptor 1c (FGFR1c). Its downstream extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK signaling pathway regulates the expression of several transcription factors and the GALNT3 gene, which encodes GalNAc-T3, which plays a role in the regulation of posttranslational modification of FGF23 protein, which in turn enhances FGF23 production. The FGFR1c-GALNT3 gene axis is considered to be the most important mechanism for regulating the production of FGF23 in bone in the response to a high phosphate diet. Thus-in the regulation of FGF23 production and blood phosphate levels-FGFR1c may be considered to function as a phosphate-sensing molecule. A feedback mechanism, in which FGFR1c and FGF23 are involved, is present in blood phosphate regulation. In addition, other reports indicate that PiT1 and PiT2 (type III sodium-phosphate cotransporters), and calcium-sensing receptor are also involved in the phosphate-sensing mechanism. In the present chapter, we summarize new insights on phosphate-sensing mechanisms.

BFGF stimulated plasminogen activation factors, but inhibited alkaline phosphatase and SPARC in stem cells from apical Papilla: Involvement of MEK/ERK, TAK1 and p38 signaling

IntroductionBasic fibroblast growth factor (bFGF) plays a critical role in odontoblast differentiation and dentin matrix deposition, thereby aiding pulpo-dentin repair and regeneration. ObjectivesThe purpose of this study was to clarify the effects of bFGF on plasminogen activation factors, TIMP-1), ALP; and SPARC (osteonectin) expression/production of stem cells from apical papilla (SCAP) in vitro; and the involvement of MEK/ERK, p38, Akt, and TAK1 signaling. MethodsSCAP were exposed to bFGF with/without pretreatment and co-incubation with various signal transduction inhibitors (U0126, SB203580, LY294002, and 5Z-7-oxozeaenol). The expression of FGF receptors (FGFRs), PAI-1, uPA, p-ERK, p-TAK1, and p-p38 was analyzed via immunofluorescent staining. The gene expression and protein secretion of SCAP were determined via real-time PCR and ELISA. ALP activity was evaluated via ALP staining. ResultsSCAP expressed FGFR1, 2, 3, and 4. bFGF stimulated the PAI-1, uPA, uPAR, and TIMP-1 mRNA expression (p < 0.05). bFGF induced PAI-1, uPA, and soluble uPAR production (p < 0.05) but suppressed the ALP activity and SPARC production (p < 0.05) of SCAP. bFGF stimulated ERK, TAK1, and p38 phosphorylation of SCAP. U0126 (a MEK/ERK inhibitor) and 5Z-7-oxozeaenol (a TAK1 inhibitor) attenuated the bFGF-induced PAI-1, uPA, uPAR, and TIMP-1 expression and production of SCAP, but SB203580 (a p38 inhibitor) did not. LY294002, SB203580, and 5Z-7oxozeaenol could not reverse the inhibition of ALP activity caused by bFGF. Interestingly, U0126 and 5Z-7-oxozeaenol prevented the bFGF-induced decline of SPARC production (p < 0.05). ConclusionbFGF may regulate fibrinolysis and matrix turnover via modulation of PAI-1, uPA, uPAR, and TIMP-1, but bFGF inhibited the differentiation (ALP, SPARC) of SCAP. These events are mainly regulated by MEK/ERK, p38, and TAK1. Combined use of bFGF and SCAP may facilitate pulpal/root repair and regeneration via regulation of the plasminogen activation system, migration, matrix turnover, and differentiation of SCAP.

Investigation of HoxB3 and Growth Factors Expression in Placentas of Various Gestational Ages.

An evaluation of transforming growth factor beta (TGFβ), hepatocyte growth factor (HGF), basic fibroblast growth factor (FGF-2), fibroblast growth factors receptor 1 (FGFR1) and Hox-positive cells in the human placenta, and their correlation with gestational time at delivery and pregnancy outcomes, may provide not only a better understanding of the role of Hox genes and growth factors in human development, but also may be of clinical importance in reproductive medicine. This study analyzed the immunohistochemical identification of TGFβ, HGF, FGF-2, FGFR1 and HoxB3 in placentas of various gestational ages. We found few (+) TGFβ, moderate (++) FGF-2 and numerous (+++) HGF and FGFR1 positive structures. Occasional (0/+) to numerous (+++) HoxB3-positive structures were detected in different types of placental cells specifically, cytotrophoblasts, syncytiotrophoblast, extravillous trophoblasts, and Höfbauer cells. Correlating the appearance of HoxB3 staining in placentas with neonatal parameters, we found a statistically significant negative correlation with ponderal index (r = −0.323, p = 0.018) and positive correlation with neonate body length (r = 0.541, p = 0.046). The number of HoxB3-positive cells did not correlate with growth factors and gestational age, but with neonatal anthropometrical parameters, indicating the role of HoxB3 not only in placental development, but also in the longitudinal growth of the fetus. TGFβ and FGF-2 did not play a significant role in the development of the placenta beyond 22nd week of pregnancy, while HGF and FGFR1 immunoreactive cells increased with advancing gestation, indicating increasingly evolving maturation (growth, proliferation) of the placenta, especially in the third trimester.

Fibroblast Growth Factor-1 Activates Neurons in the Arcuate Nucleus and Dorsal Vagal Complex

Central administration of fibroblast growth factor-1 (FGF1) results in long-lasting resolution of hyperglycemia in various rodent models, but the pre- and postsynaptic mechanisms mediating the central effects of FGF1 are unknown. Here we utilize electrophysiology recordings from neuronal populations in the arcuate nucleus of the hypothalamus (ARH), nucleus of the solitary tract (NTS), and area postrema (AP) to investigate the mechanisms underlying FGF1 actions. While FGF1 did not alter membrane potential in ARH-NPY-GFP neurons, it reversibly depolarized 83% of ARH-POMC-EGFP neurons and decreased the frequency of inhibitory inputs onto ARH-POMC-EGFP neurons. This depolarizing effect persisted in the presence of FGF receptor (R) blocker FIIN1, but was blocked by pretreatment with the voltage-gated sodium channel (VGSC) blocker tetrodotoxin (TTX). Non-FGF1 subfamilies can activate vascular endothelial growth factor receptors (VEGFR). Surprisingly, the VEGFR inhibitors axitinib and BMS605541 blocked FGF1 effects on ARH-POMC-EGFP neurons. We also demonstrate that FGF1 induces c-Fos in the dorsal vagal complex, activates NTS-NPY-GFP neurons through a FGFR mediated pathway, and requires VGSCs to activate AP neurons. We conclude that FGF1 acts in multiple brain regions independent of FGFRs. These studies present anatomical and mechanistic pathways for the future investigation of the pharmacological and physiological role of FGF1 in metabolic processes.

Intrahepatic cholangiocyte regeneration from an Fgf-dependent extrahepatic progenitor niche in a zebrafishmodel of Alagille Syndrome.

Alagille Syndrome (ALGS) is a congenital disorder caused by mutations in the Notch ligand gene JAGGED1, leading to neonatal loss of intrahepatic duct (IHD) cells and cholestasis. Cholestasis can resolve in certain patients with ALGS, suggesting regeneration of IHD cells. However, the mechanisms driving IHD cell regeneration following Jagged loss remains unclear. Here, we show that cholestasis due to developmental loss of IHD cells can be consistently phenocopied in zebrafish with compound jagged1b and jagged2b mutations or knockdown. Leveraging the transience of jagged knockdown in juvenile zebrafish, we find that resumption of Jagged expression leads to robust regeneration of IHD cells through a Notch-dependent mechanism. Combining multiple lineage tracing strategies with whole-liver three-dimensional imaging, we demonstrate that the extrahepatic duct (EHD) is the primary source of multipotent progenitors that contribute to the regeneration, but not to the development, of IHD cells. Hepatocyte-to-IHD cell transdifferentiation is possible but rarely detected. Progenitors in the EHD proliferate and migrate into the liver with Notch signaling loss and differentiate into IHD cells if Notch signaling increases. Tissue-specific mosaic analysis with an inducible dominant-negative Fgf receptor suggests that Fgf signaling from the surrounding mesenchymal cells maintains this extrahepatic niche by directly preventing premature differentiation and allocation of EHD progenitors to the liver. Indeed, transcriptional profiling and functional analysis of adult mouse EHD organoids uncover their distinct differentiation and proliferative potential relative to IHD organoids. Our data show that IHD cells regenerate upon resumption of Jagged/Notch signaling, from multipotent progenitors originating from an Fgf-dependent extrahepatic stem cell niche. We posit that if Jagged/Notch signaling is augmented, through normal stochastic variation, gene therapy, or a Notch agonist, regeneration of IHD cells in patients with ALGS may be enhanced.

Novel involvement of PLD-PKCδ-CREB axis in regulating FGF-2-mediated pentraxin 3 production in human nasal fibroblast cells.

A higher expression level of mitogenic fibroblast growth factor-2 (FGF-2) has been reported in human nasal mucus of both chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). Meanwhile, we have shown that long pentraxin 3 (PTX3), an essential component of humoral innate immunity that is produced at sites of infection and inflammation, was overproduced in human nasal mucosae and secretions of CRSsNP. Therefore, this study was aimed to investigate how FGF-2 regulates PTX3 expression in human CRSsNP nasal mucosa-derived fibroblast cells (hNMDFs). The FGF-2 treatment caused ptx3 mRNA expression and PTX3 protein induction and secretion. In parallel, a differential expression of FGF receptor (FGFR)-1 to FGFR-4 was observed in hNMDFs and human nasal tissues. While conventionally known PI3K/Akt/mTOR and AP-1 pathways following FGFR activation were shown to be involved, the protein kinase Cδ (PKCδ) and cAMP response element-binding protein (CREB) were also found to be as critical signaling molecules in FGF-2-induced PTX3 induction. The PKCδ and CREB activation could be detected in total cells and in the cell nucleus. Accordingly, a novel CREB binding sequence was detected in the human ptx3 promoter region and could interact with activated CREB in cells challenged with FGF-2. Surprisingly, the phospholipase D (PLD), but not phosphoinositide- and phosphatidylcholine-phospholipase C, was necessarily required for PKCδ and CREB activation. Therefore, we demonstrated here for the first time that FGF-2 mediates PTX3 production not only through PI-3K/Akt/mTOR and AP-1 activation, but also through a novel FGFR-PLD-PKCδ-CREB cellular signaling pathway.

Paracrine FGFs target skeletal muscle to exert potent anti-hyperglycemic effects

Several members of the FGF family have been identified as potential regulators of glucose homeostasis. We previously reported that a low threshold of FGF-induced FGF receptor 1c (FGFR1c) dimerization and activity is sufficient to evoke a glucose lowering activity. We therefore reasoned that ligand identity may not matter, and that besides paracrine FGF1 and endocrine FGF21, other cognate paracrine FGFs of FGFR1c might possess such activity. Indeed, via a side-by-side testing of multiple cognate FGFs of FGFR1c in diabetic mice we identified the paracrine FGF4 as a potent anti-hyperglycemic FGF. Importantly, we found that like FGF1, the paracrine FGF4 is also more efficacious than endocrine FGF21 in lowering blood glucose. We show that paracrine FGF4 and FGF1 exert their superior glycemic control by targeting skeletal muscle, which expresses copious FGFR1c but lacks β-klotho (KLB), an obligatory FGF21 co-receptor. Mechanistically, both FGF4 and FGF1 upregulate GLUT4 cell surface abundance in skeletal muscle in an AMPKα-dependent but insulin-independent manner. Chronic treatment with rFGF4 improves insulin resistance and suppresses adipose macrophage infiltration and inflammation. Notably, unlike FGF1 (a pan-FGFR ligand), FGF4, which has more restricted FGFR1c binding specificity, has no apparent effect on food intake. The potent anti-hyperglycemic and anti-inflammatory properties of FGF4 testify to its promising potential for use in the treatment of T2D and related metabolic disorders.