Role Of FGF Signaling Research Articles

FGF8-mediated gene regulation affects regional identity in human cerebral organoids.

The morphogen FGF8 establishes graded positional cues imparting regional cellular responses via modulation of early target genes. The roles of FGF signaling and its effector genes remain poorly characterized in human experimental models mimicking early fetal telencephalic development. We used hiPSC-derived cerebral organoids as an in vitro platform to investigate the effect of FGF8 signaling on neural identity and differentiation. We found that FGF8 treatment increases cellular heterogeneity, leading to distinct telencephalic and mesencephalic-like domains that co-develop in multi-regional organoids. Within telencephalic domains, FGF8 affects the anteroposterior and dorsoventral identity of neural progenitors and the balance between GABAergic and glutamatergic neurons, thus impacting spontaneous neuronal network activity. Moreover, FGF8 efficiently modulates key regulators responsible for several human neurodevelopmental disorders. Overall, our results show that FGF8 signaling is directly involved in both regional patterning and cellular diversity in human cerebral organoids and in modulating genes associated with normal and pathological neural development.

A single administration of FGF2 after renal ischemia-reperfusion injury alleviates post-injury interstitial fibrosis.

Despite lack of clinical therapy in acute kidney injury (AKI) or its progression to chronic kidney disease (CKD), administration of growth factors shows great potential in the treatment of renal repair and further fibrosis. At an early phase of AKI, administration of exogenous fibroblast growth factor 2 (FGF2) protects against renal injury by inhibition of mitochondrial damage and inflammatory response. Here, we investigated whether this treatment attenuates the long-term renal interstitial fibrosis induced by ischemia-reperfusion (I/R) injury. Unilateral renal I/R with contralateral nephrectomy was utilized as an in vivo model for AKI and subsequent CKD. Rats were randomly divided into four groups: Sham-operation group, I/R group, I/R-FGF2 group and FGF2-3D group. These groups were monitored for up to 2 months. Serum creatinine, inflammatory response and renal histopathology changes were detected to evaluate the role of FGF2 in AKI and followed renal interstitial fibrosis. Moreover, the expression of vimentin, α-SMA, CD31 and CD34 were examined. Two months after I/R injury, the severity of renal interstitial fibrosis was significantly attenuated in both of I/R-FGF2 group and FGF2-3D group, compared with the I/R group. The protective effects of FGF2 administration were associated with the reduction of high-mobility group box 1 (HMGB1)-mediated inflammatory response, the inhibition of transforming growth factor beta (TGF-β1)/Smads signaling-induced epithelial-mesenchymal transition and the maintenance of peritubular capillary structure. A single dose of exogenous FGF2 administration 1 h or 3 days after reperfusion inhibited renal fibrogenesis and thus blocked the transition of AKI to CKD. Our findings provided novel insight into the role of FGF signaling in AKI-to-CKD progression and underscored the potential of FGF-based therapy for this devastating disease.

A single cell characterisation of human embryogenesis identifies pluripotency transitions and putative anterior hypoblast centre

Following implantation, the human embryo undergoes major morphogenetic transformations that establish the future body plan. While the molecular events underpinning this process are established in mice, they remain unknown in humans. Here we characterise key events of human embryo morphogenesis, in the period between implantation and gastrulation, using single-cell analyses and functional studies. First, the embryonic epiblast cells transition through different pluripotent states and act as a source of FGF signals that ensure proliferation of both embryonic and extra-embryonic tissues. In a subset of embryos, we identify a group of asymmetrically positioned extra-embryonic hypoblast cells expressing inhibitors of BMP, NODAL and WNT signalling pathways. We suggest that this group of cells can act as the anterior singalling centre to pattern the epiblast. These results provide insights into pluripotency state transitions, the role of FGF signalling and the specification of anterior-posterior axis during human embryo development.

The Role of Fgf Signaling on Epithelial Cell Differentiation in Mouse Vagina

The mouse vagina exhibits stratified squamous epithelium, which is comprised of multiple cell layers. We previously showed that erbB signaling, induced by epithelial estrogen receptor 1 (ESR1), is required for the initial differentiation of the epithelium. However, the downstream effector that mediates terminal differentiation in the apical layers remains elusive. The contribution of fibroblast growth factor (FGF) to vaginal epithelial cell differentiation was investigated. Vaginas from wild-type or epithelium-specific Esr1 conditional knockout (cKO) mice were analyzed using immunohistochemistry and quantitative real-time RT-PCR. Of the FGF ligands examined, Fgf22 mRNA was significantly induced following estrogen treatment. Furthermore, FGF downstream signaling, phosphorylated FRS2 and ERK1/2 were exclusively expressed in the apical layers of the vaginal epithelium. No changes in such expression were observed in the Esr1 cKO mice. FGF-ERK/MAPK pathway may be a main inducer of terminal differentiation in the mouse vaginal epithelium.

Role of FGF signalling in neural crest cell migration during early chick embryo development.

SummaryFibroblast growth factor (FGF) signalling acts as one of modulators that control neural crest cell (NCC) migration, but how this is achieved is still unclear. In this study, we investigated the effects of FGF signalling on NCC migration by blocking this process. Constructs that were capable of inducing Sprouty2 (Spry2) or dominant-negative FGFR1 (Dn-FGFR1) expression were transfected into the cells making up the neural tubes. Our results revealed that blocking FGF signalling at stage HH10 (neurulation stage) could enhance NCC migration at both the cranial and trunk levels in the developing embryos. It was established that FGF-mediated NCC migration was not due to altering the expression of N-cadherin in the neural tube. Instead, we determined that cyclin D1 was overexpressed in the cranial and trunk levels when Sprouty2 was upregulated in the dorsal neural tube. These results imply that the cell cycle was a target of FGF signalling through which it regulates NCC migration at the neurulation stage.

Role of Fgf signalling in positioning neurogenic regions in the early embryonic vertebrate brain

Role of Fgf signalling in positioning neurogenic regions in the early embryonic vertebrate brain

The non-autonomous role of FGF signaling in muscle pioneer determination

The non-autonomous role of FGF signaling in muscle pioneer determination

MP52-19 NOVEL MUTATIONS OF THE CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR GENE IN CHINESE PATIENTS WITH CONGENITAL ABSENCE OF VAS DEFERENS

INTRODUCTION AND OBJECTIVES: The adult Leydig cell undergoes several stages of maturation during development which is closely regulated by luteinizing hormone (LH), thyroid hormone (TH) and androgens. Several studies have shown increased androgen production by Leydig cells when exposed to fibroblast growth factors (Fgfs). The role of Fgf signaling in Leydig cell development and function remains unknown. Our aimsare to investigate 1) Leydig cell development andmaturation using a lineage tracing marker 2) the effect fibroblast growth factor receptor 1 and 2 deletion on adult Leydig cell development and function METHODS: Tbx18cre transgenic mice were bred to either a CAG/red fluorescent protein (RFP) reporter (for lineage tracing) or to Fgfr1 and Fgfr2 floxed mice (for conditional knockouts of the receptors). Immunohistochemisty assays were performed to assess the expression pattern of the Tbx18creCAG line in the testis. Sox9 and 3-âHSD were used as markers of Sertoli cells and Leydig cells respectively. Leydig cell development in the Fgfr knock-out model was determined by gene expression using Real Time PCR at day 1, 30, 45 and 60 post birth. Leydig cell maturity was assessed with the following gene library: fetal Leydig cell (Patched and Thsb2), immature (5a-reductase) and mature (Cyp17a1, Ptgds, Sult1e1, and Hsd17b3) RESULTS: Immunohistochemical analysis of the Tbx18creCAG mice revealed expression throughout testicular interstitial cells of both fetal and adult testis. Immunolabeling with 3-âHSD and Sox9 revealed co-labeling of the RFP and 3-âHSD, but not with Sox9, indicating that Tbx18cre gene expression was only in the Leydig cell. Tbx18creFgfr1/2 knock-out mice showed under-developed Wolffian duct-derived structures in postpubertal mice compared to controls. Fetal Leydig cell gene expression markers between controls and the Fgfr1/2 knockouts were comparable from birth to maturity. Adult mutant mouse testicles did have increased expression of 5a-reductase and decrease expression of Cyp17a1, Ptgds, and Sult1e1 consistent with lack of leydig cell maturation. CONCLUSIONS: Tbx18cre mice express cre only in Leydig cells, starting in embryos, making it an ideal to lineage trace or manipulate gene expression in Leydig cells. Tbx18creFgfr1/2 knockout mice had increased expression of immature Leydig cell gene markers compared to controls, consistent with Leydig cell arresting in an immature state. Thus, Fgfr1 and 2 signaling appears to be critical for Leydig cell maturation from an immature to a mature state. Impaired Fgf signaling in the Leydig cell may be responsible for some forms idiopathic hypogonadism.

A Ser252Trp Mutation in Fibroblast Growth Factor Receptor 2 (FGFR2) Mimicking Human Apert Syndrome Reveals an Essential Role for FGF Signaling in the Regulation of Endochondral Bone Formation

A S252W mutation of fibroblast growth factor receptor 2 (FGFR2), which is responsible for nearly two-thirds of Apert syndrome (AS) cases, causes retarded development of the skeleton and skull malformation resulting from premature fusion of the craniofacial sutures. We utilized a Fgfr2+/S252W mouse (a knock-in mouse model mimicking human AS) to demonstrate decreased bone mass due to reduced trabecular bone volume, reduced bone mineral density, and shortened growth plates in the long bones. In vitro bone mesenchymal stem cells (BMSCs) culture studies revealed that the mutant mice showed reduced BMSC proliferation, a reduction in chondrogenic differentiation, and reduced mineralization. Our results suggest that these phenomena are caused by up-regulation of p38 and Erk1/2 phosphorylation. Treatment of cultured mutant bone rudiments with SB203580 or PD98059 resulted in partial rescue of the bone growth retardation. The p38 signaling pathway especially was found to be responsible for the retarded long bone development. Our data indicate that the S252W mutation in FGFR2 directly affects endochondral ossification, resulting in growth retardation of the long bone. We also show that the p38 and Erk1/2 signaling pathways partially mediate the effects of the S252W mutation of FGFR2 on long bone development.

Angiotensin II‐induced cardiac hypertrophy and fibrosis are promoted in mice lacking Fgf16

Fibroblast growth factors (Fgfs) are pleiotropic proteins involved in development, repair and metabolism. Fgf16 is predominantly expressed in the heart. However, as the heart function is essentially normal in Fgf16 knockout mice, its role has remained unclear. To elucidate the pathophysiological role of Fgf16 in the heart, we examined angiotensin II-induced cardiac hypertrophy and fibrosis in Fgf16 knockout mice. Angiotensin II-induced cardiac hypertrophy and fibrosis were significantly promoted by enhancing Tgf-β1 expression in Fgf16 knockout mice. Unexpectedly, the response to cardiac remodeling was apparently opposite to that in Fgf2 knockout mice. These results indicate that Fgf16 probably prevents cardiac remodeling, although Fgf2 promotes it. Cardiac Fgf16 expression was induced after the induction of Fgf2 expression by angiotensin II. In cultured cardiomyocytes, Fgf16 expression was promoted by Fgf2. In addition, Fgf16 antagonized Fgf2-induced Tgf-β1 expression in cultured cardiomyocytes and noncardiomyocytes. These results suggest a possible mechanism whereby Fgf16 prevents angiotensin II-induced cardiac hypertrophy and fibrosis by antagonizing Fgf2. The present findings should provide new insights into the roles of Fgf signaling in cardiac remodeling.

Fgf-Dependent Glial Cell Bridges Facilitate Spinal Cord Regeneration in Zebrafish

Adult zebrafish show a remarkable capacity to regenerate their spinal column after injury, an ability that stands in stark contrast to the limited repair that occurs within the mammalian CNS post-injury. The reasons for this interspecies difference in regenerative capacity remain unclear. Here we demonstrate a novel role for Fgf signaling during glial cell morphogenesis in promoting axonal regeneration after spinal cord injury. Zebrafish glia are induced by Fgf signaling, to form an elongated bipolar morphology that forms a bridge between the two sides of the resected spinal cord, over which regenerating axons actively migrate. Loss of Fgf function inhibits formation of this "glial bridge" and prevents axon regeneration. Despite the poor potential for mammalian axonal regeneration, primate astrocytes activated by Fgf signaling adopt a similar morphology to that induced in zebrafish glia. This suggests that differential Fgf regulation, rather than intrinsic cell differences, underlie the distinct responses of mammalian and zebrafish glia to injury.

Uncovering the ancestral role of FGF signaling in neural development

Uncovering the ancestral role of FGF signaling in neural development

Investigating the Role of FGF Signaling in Pancreatic Cancer

Investigating the Role of FGF Signaling in Pancreatic Cancer

Abstract 1101: A novel role for FGFR in breast cancer

Abstract FGF-10 and its two receptors, FGFR1 and FGFR2, have been implicated in breast cancer susceptibility and/or progression, suggesting that, as with several other cancers, FGF signalling may be co-opted by breast cancer cells to give them a growth advantage. We aim to elucidate the role of FGF signalling in breast cancer progression and behaviour. We determined the expression levels of FGFs and FGFRs in a number of breast cancer cell lines, identifying a positive correlation of FGF-10 and FGFR1 expression with ER status. This is particularly interesting, given the correlation between amplification of FGFR1 and poor prognosis in ER positive breast cancer. To investigate the effects of FGFR signalling, we treated both weakly and highly metastatic human breast cancer cell lines (MCF-7 and MDA-MB-231, respectively), with recombinant FGF-10. This elicited rapid ERK phosphorylation, which was abrogated by pre-treatment with an FGFR inhibitor, PD173074. Interestingly, the signalling pathways downstream of FGF-10 stimulation differed between the two cell lines, with MCF-7 cells signalling via FGF Receptor Substrate 2 (FRS2), whereas MDA-MB-231 cells did not. FGF-10 treatment stimulated cell proliferation only in MCF-7 cells, suggesting that its mitogenic effect acts via P-FRS2, whereas it drove survival and migration equally in both cell lines. Using a breast cancer organotypic model we observed, specifically in cells that had invaded into the stroma, FGFR1 was localised to the nucleus. Using immunocytochemistry we have also identified nuclear FGFR1 in invasive lobular carcinoma. In 2D culture, immunofluorescence and subcellular fractionation of breast cancer cells revealed that FGF-10 treatment stimulated nuclear localisation of a C-terminal fragment of FGFR1, an effect peaking after 1 hour and dependent on active FGF signalling. Using specific inhibitors and RNAi, we identified granzyme B (GrB) as the protease responsible for FGFR1 cleavage. Importantly, inhibition of GrB blocked accumulation of nuclear FGFR1 upon FGF-10 treatment and increased total levels of full length FGFR1. Furthermore, GrB inhibition enhanced the effect FGF-10 stimulation had on phosphorylation of FRS2 and ERK. Functionally, GrB inhibition blocked the pro-migratory effect of FGF-10 treatment suggesting that nuclear localisation of the receptor may be critical for cell migration. To elucidate the role of nuclear FGFR1, we performed ChIP on chip studies, identifying a number of putative target genes. Modulating of FGFR1 levels showed that FGFR1 can activate or suppress expression of these target genes, perhaps reflecting an invasive signature. Our studies identify an entirely novel mechanism by which FGF signalling may regulate cancer cell behaviour. Establishing the functional, prognostic and therapeutic relevance of FGF signalling in breast cancer is critical for the development of new targeting strategies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1101. doi:10.1158/1538-7445.AM2011-1101

The role of FGF-signaling in early neural specification of human embryonic stem cells

The mechanisms that govern human neural specification are not completely characterized. Here we used human embryonic stem cells (hESCs) to study the role of fibroblast growth factor (FGF)-signaling in early human neural specification. Differentiation was obtained by culturing clusters of hESCs in chemically-defined medium. We show that FGF-signaling, which is endogenously active during early differentiation of hESCs, induces early neural specification, while its blockage inhibits neuralization. The early neuralization effect of FGF-signaling is not mediated by promoting the proliferation of existing neural precursors (NPs) or prevention of their apoptosis. The neural instructive effect of FGF-signaling occurs after an initial FGF-independent differentiation into primitive ectoderm-like fate. We further show that FGF-signaling can induce neuralization by a mechanism which is independent of modulating bone morphogenic protein (BMP)-signaling. Still, FGF-signaling is not essential for hESC neuralization which can occur in the absence of FGF and BMP-signaling. Collectively, our data suggest that human neural induction is instructed by FGF-signaling, though neuralization of hESCs can occur in its absence.

The role of FGF signaling in the establishment and maintenance of mesodermal gene expression in Xenopus

FGF signaling is important for the formation of mesoderm in vertebrates, and when it is perturbed in Xenopus, most trunk and tail mesoderm fails to form. Here we have further dissected the activities of FGF in patterning the embryo by addressing its inductive and maintenance roles. We show that FGF signaling is necessary for the establishment of xbra expression in addition to its well-characterized role in maintaining xbra expression. The role of FGF signaling in organizer formation is not clear in Xenopus. We find that FGF signaling is essential for the initial specification of paraxial mesoderm but not for activation of several pan-mesodermal and most organizer genes; however, early FGF signaling is necessary for the maintenance of organizer gene expression into the neurula stage. Inhibition of FGF signaling prevents VegT activation of specific mesodermal transcripts. These findings illuminate how FGF signaling contributes to the establishment of distinct types of mesoderm.

P36. The role of FGF-signalling in osteosarcoma: A potential therapeutic target?

Osteosarcoma (OS) is the most common human primary skeletal malignancy. However, current treatment strategies rely heavily on surgical intervention and there are no curative systemic therapies available for the treatment of OS. Deregulated signalling through the Fibroblast Growth Factor Receptor (FGFR) family has recently been implicated in both the pathogenesis as well as skeletal metastasis of both breast and prostate cancer. However, the role and therapeutic potential of FGF signalling in OS is not well established.

The role of FGF signalling in the formation of the primitive streak

The role of FGF signalling in the formation of the primitive streak

WITHDRAWN: Examining the role of FGF signaling in lung branching morphogenesis

WITHDRAWN: Examining the role of FGF signaling in lung branching morphogenesis

Fgf19 regulated by Hh signaling is required for zebrafish forebrain development

Fibroblast growth factor (Fgf) signaling plays important roles in brain development. Fgf3 and Fgf8 are crucial for the formation of the forebrain and hindbrain. Fgf8 is also required for the midbrain to form. Here, we identified zebrafish Fgf19 and examined its roles in brain development by knocking down Fgf19 function. We found that Fgf19 expressed in the forebrain, midbrain and hindbrain was involved in cell proliferation and cell survival during embryonic brain development. Fgf19 was also essential for development of the ventral telencephalon and diencephalon. Regional specification is linked to cell type specification. Fgf19 was also essential for the specification of γ-aminobutyric acid (GABA)ergic interneurons and oligodendrocytes generated in the ventral telencephalon and diencephalon. The cross talk between Fgf and Hh signaling is critical for brain development. In the forebrain, Fgf19 expression was down-regulated on inhibition of Hh but not of Fgf3/Fgf8, and overexpression of Fgf19 rescued partially the phenotype on inhibition of Hh. The present findings indicate that Fgf19 signaling is crucial for forebrain development by interacting with Hh and provide new insights into the roles of Fgf signaling in brain development.