The Fgf families in humans, mice, and zebrafish: their evolutional processes and roles in development, metabolism, and disease

Real-time monitoring of an endogenous Fgf8a gradient attests to its role as a morphogen during zebrafish gastrulation

Morphogen gradients impart positional information to cells in a homogenous tissue field. Fgf8a, a highly conserved growth factor, has been proposed to act as a morphogen during zebrafish gastrulation. However, technical limitations have so far prevented direct visualization of the endogenous Fgf8a gradient and confirmation of its morphogenic activity. Here, we monitor Fgf8a propagation in the developing neural plate using a CRISPR/Cas9-mediated EGFP knock-in at the endogenous fgf8a locus. By combining sensitive imaging with single-molecule fluorescence correlation spectroscopy, we demonstrate that Fgf8a, which is produced at the embryonic margin, propagates by diffusion through the extracellular space and forms a graded distribution towards the animal pole. Overlaying the Fgf8a gradient curve with expression profiles of its downstream targets determines the precise input-output relationship of Fgf8a-mediated patterning. Manipulation of the extracellular Fgf8a levels alters the signaling outcome, thus establishing Fgf8a as a bona fide morphogen during zebrafish gastrulation. Furthermore, by hindering Fgf8a diffusion, we demonstrate that extracellular diffusion of the protein from the source is crucial for it to achieve its morphogenic potential.

Roles of Fibroblast Growth Factors in the Axon Guidance

Fibroblast growth factors (FGFs) have been widely studied by virtue of their ability to regulate many essential cellular activities, including proliferation, survival, migration, differentiation and metabolism. Recently, these molecules have emerged as the key components in forming the intricate connections within the nervous system. FGF and FGF receptor (FGFR) signaling pathways play important roles in axon guidance as axons navigate toward their synaptic targets. This review offers a current account of axonal navigation functions performed by FGFs, which operate as chemoattractants and/or chemorepellents in different circumstances. Meanwhile, detailed mechanisms behind the axon guidance process are elaborated, which are related to intracellular signaling integration and cytoskeleton dynamics.

Pre-granulosa cell-derived FGF23 protects oocytes from premature apoptosis during primordial follicle formation by inhibiting p38 MAPK in mice

A large number of oocytes in the perinatal ovary in rodents get lost for unknown reasons. The granulosa cell-oocyte mutual communication is pivotal for directing formation of the primordial follicle, however little is known if paracrine factors participate in modulating programmed oocyte death perinatally. We report here that pre-granulosa cell-derived fibroblast growth factor 23 (FGF23) functioned in preventing oocyte apoptosis in the perinatal mouse ovary. Our results showed that FGF23 was exclusively expressed in pre-granulosa cells while fibroblast growth factor receptors (FGFRs) were specifically expressed in the oocytes in perinatal ovaries. FGFR1 was one of the representative receptors in mediating FGF23 signaling during the formation of the primordial follicle. In cultured ovaries, the number of alive oocytes declines significantly, accompanied by the activation of the p38 MAPK signaling pathway, under the condition of FGFR1 disruption by specific inhibitors of FGFR1 or silencing of Fgf23. As a result, oocyte apoptosis increased and eventually led to a decrease in the number of germ cells in perinatal ovaries following the treatments. In the perinatal mouse ovary, pre-granulosa cell-derived FGF23 binds to FGFR1 and activates at least, the p38 MAPK signaling pathway, thereby regulating the level of apoptosis during primordial follicle formation. This study re-emphasizes the importance of granulosa cell - oocyte mutual communication in modulating primordial follicle formation and supporting oocyte survival under physiological conditions.

Fibroblast growth factor pathway component expression in the regenerating zebrafish fin

Adult zebrafish regenerate their appendages (fins) after amputation including the regeneration of bone structures (fin rays). Fibroblast growth factor (Fgf) signaling, which is involved in morphogenetic processes during development, has been shown to be essential for the process of fin regeneration. Moreover, mutations in Fgf pathway component genes lead to abnormal skeletal growth in teleosts and mammals, including humans, illustrating the importance of Fgf signaling in the growth control of tissues. Here, we revisited Fgf signaling pathway component expression by RNA in situ hybridization to test for the expression of about half of the ligands and all receptors of the pathway in the regenerating zebrafish fin. Expression patterns of fgf7, fgf10b, fgf12b, fgf17b and fgfr1b have not been reported in the literature before. We summarize and discuss known and novel localization of expression and find that all five Fgf receptors (fgfr1a, fgfr1b, fgfr2, fgfr3 and fgfr4) and most of the tested ligands are expressed in specific regions of the regenerate. Our work provides a basis to study domain specific functions of Fgf signaling in the regenerating teleost appendage.

Induction of Angiogenesis by Genetically Modified Human Umbilical Cord Blood Mononuclear Cells

Stimulating the process of angiogenesis in treating ischemia-related diseases is an urgent task for modern medicine, which can be achieved through the use of different cell types. Umbilical cord blood (UCB) continues to be one of the attractive cell sources for transplantation. The goal of this study was to investigate the role and therapeutic potential of gene-engineered umbilical cord blood mononuclear cells (UCB-MC) as a forward-looking strategy for the activation of angiogenesis. Adenovirus constructs Ad-VEGF, Ad-FGF2, Ad-SDF1α, and Ad-EGFP were synthesized and used for cell modification. UCB-MCs were isolated from UCB and transduced with adenoviral vectors. As part of our in vitro experiments, we evaluated the efficiency of transfection, the expression of recombinant genes, and the secretome profile. Later, we applied an in vivo Matrigel plug assay to assess engineered UCB-MC's angiogenic potential. We conclude that hUCB-MCs can be efficiently modified simultaneously with several adenoviral vectors. Modified UCB-MCs overexpress recombinant genes and proteins. Genetic modification of cells with recombinant adenoviruses does not affect the profile of secreted pro- and anti-inflammatory cytokines, chemokines, and growth factors, except for an increase in the synthesis of recombinant proteins. hUCB-MCs genetically modified with therapeutic genes induced the formation of new vessels. An increase in the expression of endothelial cells marker (CD31) was revealed, which correlated with the data of visual examination and histological analysis. The present study demonstrates that gene-engineered UCB-MC can be used to stimulate angiogenesis and possibly treat cardiovascular disease and diabetic cardiomyopathy.

Identification, Characterization and Functional Analysis of Fibroblast Growth Factors in Black Rockfish (Sebastes schlegelii)

Fibroblast growth factors (FGFs) are short polypeptides that play essential roles in various cellular biological processes, including cell migration, proliferation, and differentiation, as well as tissue regeneration, immune response, and organogenesis. However, studies focusing on the characterization and function of FGF genes in teleost fishes are still limited. In this study, we identified and characterized expression patterns of 24 FGF genes in various tissues of embryonic and adult specimens of the black rockfish (Sebates schlegelii). Nine FGF genes were found to play essential roles in myoblast differentiation, as well as muscle development and recovery in juvelines of S. schlegelii. Moreover, sex-biased expression pattern of multiple FGF genes was recorded in the species' gonads during its development. Among them, expression of the FGF1 gene was recorded in interstitial and sertoli cells of testes, promoting germ-cell proliferation and differentiation. In sum, the obtained results enabled systematic and functional characterization of FGF genes in S. schlegelii, laying a foundation for further studies on FGF genes in other large teleost fishes.

Prospective use of amniotic mesenchymal stem cell metabolite products for tissue regeneration

Chronic disease can cause tissue and organ damage constituting the largest obstacle to therapy which, in turn, reduces patients' quality-adjusted life-year. Degenerative diseases such as osteoporosis, Alzheimer's disease, Parkinson's disease, and infectious conditions such as hepatitis, cause physical injury to organs. Moreover, damage resulting from chronic conditions such as diabetes can also culminate in the loss of organ function. In these cases, organ transplantation constitutes the therapy of choice, despite the associated problems of immunological rejection, potential disease transmission, and high morbidity rates. Tissue regeneration has the potential to heal or replace tissues and organs damaged by age, disease, or trauma, as well as to treat disabilities. Stem cell use represents an unprecedented strategy for these therapies. However, product availability and mass production remain challenges. A novel therapeutic alternative involving amniotic mesenchymal stem cell metabolite products (AMSC-MP) has been developed using metabolites from stem cells which contain cytokines and growth factors. Its potential role in regenerative therapy has recently been explored, enabling broad pharmacological applications including various gastrointestinal, lung, bladder and renal conditions, as well as the treatment of bone wounds, regeneration and skin aging due to its low immunogenicity and anti-inflammatory effects. The various kinds of growth factors present in AMSC-MP, namely bFGF, VEGF, TGF-β, EGF and KGF, have their respective functions and activities. Each growth factor is formed by different proteins resulting in molecules with various physicochemical properties and levels of stability. This knowledge will assist in the manufacture and application of AMSC-MP as a therapeutic agent.

Combined genetic deletion of GDF15 and FGF21 has modest effects on body weight, hepatic steatosis and insulin resistance in high fat fed mice

OBJECTIVES

Obesity in humans and mice is associated with elevated levels of two hormones responsive to cellular stress, namely GDF15 and FGF21. Over-expression of each of these is associated with weight loss and beneficial metabolic changes but where they are secreted from and what they are required for physiologically in the context of overfeeding remains unclear.

METHODS

Here we used tissue selective knockout mouse models and human transcriptomics to determine the source of circulating GDF15 in obesity. We then generated and characterized the metabolic phenotypes of GDF15/FGF21 double knockout mice.

RESULTS

Circulating GDF15 and FGF21 are both largely derived from the liver, rather than adipose tissue or skeletal muscle, in obese states. Combined whole body deletion of FGF21 and GDF15 does not result in any additional weight gain in response to high fat feeding but it does result in significantly greater hepatic steatosis and insulin resistance than that seen in GDF15 single knockout mice.

CONCLUSIONS

Collectively the data suggest that overfeeding activates a stress response in the liver which is the major source of systemic rises in GDF15 and FGF21. These hormones then activate pathways which reduce this metabolic stress.

Comprehensive analysis of potential cellular communication networks in advanced osteosarcoma using single-cell RNA sequencing data

Osteosarcoma (OS) is a common bone cancer in children and adolescents, and metastasis and recurrence are the major causes of poor treatment outcomes. A better understanding of the tumor microenvironment is required to develop an effective treatment for OS. In this paper, a single-cell RNA sequencing dataset was taken to a systematic genetic analysis, and potential signaling pathways linked with osteosarcoma development were explored. Our findings revealed 25 clusters across 11 osteosarcoma tissues, with 11 cell types including “Chondroblastic cells”, “Osteoblastic cells”, “Myeloid cells”, “Pericytes”, “Fibroblasts”, “Proliferating osteoblastic cells”, “Osteoclasts”, “TILs”, “Endothelial cells”, “Mesenchymal stem cells”, and “Myoblasts”. The results of Cell communication analysis showed 17 potential cellular communication networks including “COLLAGEN signaling pathway network”, “CD99 signaling pathway network”, “PTN signaling pathway network”, “MIF signaling pathway network”, “SPP1 signaling pathway network”, “FN1 signaling pathway network”, “LAMININ signaling pathway network”, “FGF signaling pathway network”, “VEGF signaling pathway network”, “GALECTIN signaling pathway network”, “PERIOSTIN signaling pathway network”, “VISFATIN signaling pathway network”, “ITGB2 signaling pathway network”, “NOTCH signaling pathway network”, “IGF signaling pathway network”, “VWF signaling pathway network”, “PDGF signaling pathway network”. This research may provide novel insights into the pathophysiology of OS’s molecular processes.

Hair Growth Regulation by Fibroblast Growth Factor 12 (FGF12)

The fibroblast growth factor (FGF) family has various biological functions, including cell growth, tissue regeneration, embryonic development, metabolism, and angiogenesis. In the case of hair growth, several members of the FGF family, such as FGF1 and FGF2, are involved in hair growth, while FGF5 has the opposite effect. In this study, the regulation of the hair growth cycle by FGF12 was investigated. To observe its effect, the expression of FGF12 was downregulated in mice and outer root sheath (ORS) by siRNA transfection, while FGF12 overexpression was carried out using FGF12 adenovirus. For the results, FGF12 was primarily expressed in ORS cells with a high expression during the anagen phase of hair follicles. Knockdown of FGF12 delayed telogen-to-anagen transition in mice and decreased the hair length in vibrissae hair follicles. It also inhibited the proliferation and migration of ORS cells. On the contrary, FGF12 overexpression increased the migration of ORS cells. FGF12-overexpressed ORS cells induced the telogen-to-anagen transition in the animal model. In addition, FGF12 overexpression regulated the expression of PDGF-CC, MDK, and HB-EGF, and treatment of these factors exhibited hair growth promotion. Altogether, FGF12 promoted hair growth by inducing the anagen phase of hair follicles, suggesting the potential for hair loss therapy.

A multicenter investigator-initiated Phase 2 trial of E7090 in patients with advanced or recurrent solid tumor with fibroblast growth factor receptor (FGFR) gene alteration: FORTUNE trial

Background

Aberrant fibroblast growth factor receptor (FGFR) signaling can substantially influence oncogenicity. Despite that FGFR gene abnormality is often detected by cancer genome profiling tests, there is no tumor-agnostic approval yet for these aberrations. E7090 (tasurgratinib) is an orally available selective tyrosine kinase inhibitor of FGFR1-3. Specific FGFR alterations were previously reported to be highly sensitive to E7090 based on a high-throughput functional evaluation method, called mixed-all-nominated-mutants-in-one (MANO) method, narrowing down the most promising targets. This trial was focused on the alterations identified by the MANO method and was performed under the nationwide large registry network for rare cancers in Japan (MASTER KEY Project).

Methods/Design

This single-arm Phase 2 trial was designed to evaluate the safety and efficacy of E7090 in patients with advanced or recurrent solid tumors harboring FGFR alterations. Three cohorts were set based on the type of FGFR alterations and the results of MANO method. A maximum of 45 patients will be enrolled from 5 institutions over 2.5 years. E7090 will be administered once daily as an oral single agent in 28-day cycles. The primary endpoint is the objective overall response rate; whereas, the secondary endpoints include progression-free survival, overall survival, disease control rate, safety, duration of response, and time to response. Ethics approval was granted by the National Cancer Center Hospital Certified Review Board. Patient enrollment began in June 2021.

Discussion

A unique investigator-initiated multicenter Phase 2 trial was designed based on the results of preclinical investigation aiming to acquire the approval of E7090 for solid tumors harboring FGFR gene alterations. The findings may serve as a novel model for the development of tumor-agnostic molecular targeted therapies against rare genetic abnormalities.

Trial registration

Japan Registry of Clinical Trial: jRCT2031210043 (registered April 20, 2021) ClinicalTrials.gov: NCT04962867 (registered July 15, 2021).

Overview of sialylation status in human nervous and skeletal muscle tissues during aging

Sialic acids (Sias) are a large and heterogeneous family of electronegatively charged nine-carbon monosaccharides containing a carboxylic acid and are mostly found as terminal residues in glycans of glycoproteins and glycolipids such as gangliosides. They are linked to galactose or N-acetylgalactosamine via α2,3 or α2,6 linkage, or to other Sias via α2,8 or more rarely α2,9 linkage, resulting in mono, oligo and polymeric forms. Given their characteristics, Sias play a crucial role in a multitude of human tissue biological processes in physiological and pathological conditions, ranging from development and growth to adult life until aging. Here, we review the sialylation status in human adult life focusing on the nervous and skeletal muscle tissues, which both display significant structural and functional changes during aging, strongly impacting on the whole human body and, therefore, on the quality of life. In particular, this review highlights the fundamental roles played by different types of glycoconjugates Sias in several cellular biological processes in the nervous and skeletal muscle tissues during adult life, also discussing how changes in Sia content during aging may contribute to the physiological decline of physical and nervous functions and to the development of age-related degenerative pathologies. Based on our current knowledge, further in-depth investigations could help to develop novel prophylactic strategies and therapeutic approaches that, by maintaining and/or restoring the correct sialylation status in the nervous and skeletal muscle tissues, could contribute to aging slowing and the prevention of age-related pathologies.

Shedding light on developmental ERK signaling with genetically encoded biosensors

The extracellular signal-regulated kinase (ERK) pathway governs cell proliferation, differentiation and migration, and therefore plays key roles in various developmental and regenerative processes. Recent advances in genetically encoded fluorescent biosensors have unveiled hitherto unrecognized ERK activation dynamics in space and time and their functional importance mainly in cultured cells. However, ERK dynamics during embryonic development have still only been visualized in limited numbers of model organisms, and we are far from a sufficient understanding of the roles played by developmental ERK dynamics. In this Review, we first provide an overview of the biosensors used for visualization of ERK activity in live cells. Second, we highlight the applications of the biosensors to developmental studies of model organisms and discuss the current understanding of how ERK dynamics are encoded and decoded for cell fate decision-making.

Pathophysiological Implications of Imbalances in Fibroblast Growth Factor 23 in the Development of Diabetes

Observational studies have associated the increase in fibroblast growth factor (FGF) 23 levels, the main regulator of phosphate levels, with the onset of diabetes. These studies open the debate on the plausible existence of undescribed diabetogenic mechanisms derived from chronic supraphysiological levels of FGF23, a prevalent condition in chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. These maladaptive and diabetogenic responses to FGF23 may occur at different levels, including a direct effect on the pancreatic ß cells, and an indirect effect derived from the stimulation of the synthesis of pro-inflammatory factors. Both mechanisms could be mediated by the binding of FGF23 to noncanonical receptor complexes with the subsequent overactivation of signaling pathways that leads to harmful effects. The canonical binding of FGF23 to the receptor complex formed by the receptor FGFR1c and the coreceptor αKlotho activates Ras/MAPK/ERK signaling. However, supraphysiological concentrations of FGF23 favor non-αKlotho-dependent binding of this molecule to other FGFRs, which could generate an undesired overactivation of the PLCγ/CN/NFAT pathway, as observed in cardiomyocytes and hepatocytes. Moreover, the decrease in αKlotho expression may constitute a contributing factor to the appearance of these effects by promoting the nonspecific activation of the PLCγ/CN/NFAT to the detriment of the αKlotho-dependent Ras/MAPK/ERK pathway. The description of these mechanisms would allow the development of new therapeutic targets susceptible to be modified by dietary changes or by pharmacological intervention.

Advances of Fibroblast Growth Factor/Receptor Signaling Pathway in Hepatocellular Carcinoma and its Pharmacotherapeutic Targets

Hepatocellular carcinoma (HCC) is a type of primary liver cancer with poor prognosis, and its incidence and mortality rate are increasing worldwide. It is refractory to conventional chemotherapy and radiotherapy owing to its high tumor heterogeneity. Accumulated genetic alterations and aberrant cell signaling pathway have been characterized in HCC. The fibroblast growth factor (FGF) family and their receptors (FGFRs) are involved in diverse biological activities, including embryonic development, proliferation, differentiation, survival, angiogenesis, and migration, etc. Data mining results of The Cancer Genome Atlas demonstrate high levels of FGF and/or FGFR expression in HCC tumors compared with normal tissues. Moreover, substantial evidence indicates that the FGF/FGFR signaling axis plays an important role in various mechanisms that contribute to HCC development. At present, several inhibitors targeting FGF/FGFR, such as multikinase inhibitors, specific FGFR4 inhibitors, and FGF ligand traps, exhibit antitumor activity in preclinical or early development phases in HCC. In this review, we summarize the research progress regarding the molecular implications of FGF/FGFR-mediated signaling and the development of FGFR-targeted therapeutics in hepatocarcinogenesis.

The Roles and Pharmacological Effects of FGF21 in Preventing Aging-Associated Metabolic Diseases

With the continuous improvement of living standards but the lack of exercise, aging-associated metabolic diseases such as obesity, type 2 diabetes mellitus (T2DM), and non-alcoholic fatty liver disease (NAFLD) are becoming a lingering dark cloud over society. Studies have found that metabolic disorders are near related to glucose, lipid metabolism, and cellular aging. Fibroblast growth factor 21 (FGF21), a member of the FGFs family, efficiently regulates the homeostasis of metabolism and cellular aging. By activating autophagy genes and improving inflammation, FGF21 indirectly delays cellular aging and directly exerts anti-aging effects by regulating aging genes. FGF21 can also regulate glucose and lipid metabolism by controlling metabolism-related genes, such as adipose triglyceride lipase (ATGL) and acetyl-CoA carboxylase (ACC1). Because FGF21 can regulate metabolism and cellular aging simultaneously, FGF21 analogs and FGF21 receptor agonists are gradually being valued and could become a treatment approach for aging-associated metabolic diseases. However, the mechanism by which FGF21 achieves curative effects is still not known. This review aims to interpret the interactive influence between FGF21, aging, and metabolic diseases and delineate the pharmacology of FGF21, providing theoretical support for further research on FGF21.

Human Adipose-Derived Stem Cells' Paracrine Factors in Conditioned Medium Can Enhance Porcine Oocyte Maturation and Subsequent Embryo Development

An essential requirement for the success of in vitro maturation (IVM) of the oocyte is to provide an optimal microenvironment similar to in vivo conditions. Recently, somatic cell-based coculture or supplementation of a conditioned medium during IVM has been performed to obtain better quality of oocytes, because they mimic the in vivo reproductive tract by secreting paracrine factors. In this study, human adipose-derived stem cells (ASC) and their conditioned medium (ASC-CM) were applied to IVM of porcine oocytes to evaluate the effectiveness of ASC on oocyte development and subsequent embryo development. In results, both ASC and ASC-CM positively influence on oocyte maturation and embryo development by regulating growth factor receptors (VEGF, FGFR, and IGFR), apoptosis (BCL2), cumulus expansion (PTGS2, HAS2, and TNFAIP6), and oocyte maturation-related genes (GDF9 and BMP15). In particular, the fluorescence intensity of GDF9 and BMP15 was markedly upregulated in the oocytes from the ASC-CM group. Furthermore, significantly high levels of growth factors/cytokine including VEGF, bFGF, IGF-1, IL-10, and EGF were observed in ASC-CM. Additionally, the ASC-CM showed active scavenging activity by reducing the ROS production in a culture medium. Consequently, for the first time, this study demonstrated the effect of human ASC-CM on porcine oocyte development and the alteration of mRNA transcript levels in cumulus–oocyte complexes.

Role of FGF Receptors and Their Pathways in Adrenocortical Tumors and Possible Therapeutic Implications

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy and treatment of advanced disease is challenging. Clinical trials with multi-tyrosine kinase inhibitors in the past have yielded disappointing results. Here, we investigated fibroblast growth factor (FGF) receptors and their pathways in adrenocortical tumors as potential treatment targets. We performed real-time RT-PCR of 93 FGF pathway related genes in a cohort of 39 fresh frozen benign and malignant adrenocortical, 9 non-adrenal tissues and 4 cell lines. The expression of FGF receptors was validated in 166 formalin-fixed paraffin embedded (FFPE) tissues using RNA in situ hybridization (RNAscope) and correlated with clinical data. In malignant compared to benign adrenal tumors, we found significant differences in the expression of 16/94 FGF receptor pathway related genes. Genes involved in tissue differentiation and metastatic spread through epithelial to mesechymal transition were most strongly altered. The therapeutically targetable FGF receptors 1 and 4 were upregulated 4.6- and 6-fold, respectively, in malignant compared to benign adrenocortical tumors, which was confirmed by RNAscope in FFPE samples. High expression of FGFR1 and 4 was significantly associated with worse patient prognosis in univariate analysis. After multivariate adjustment for the known prognostic factors Ki-67 and ENSAT tumor stage, FGFR1 remained significantly associated with recurrence-free survival (HR=6.10, 95%CI: 1.78 - 20.86, p=0.004) and FGFR4 with overall survival (HR=3.23, 95%CI: 1.52 - 6.88, p=0.002). Collectively, our study supports a role of FGF pathways in malignant adrenocortical tumors. Quantification of FGF receptors may enable a stratification of ACC for the use of FGFR inhibitors in future clinical trials.

Hes5.9 Coordinate FGF and Notch Signaling to Modulate Gastrulation via Regulating Cell Fate Specification and Cell Migration in Xenopus tropicalis

Gastrulation drives the establishment of three germ layers and embryonic axes during frog embryonic development. Mesodermal cell fate specification and morphogenetic movements are vital factors coordinating gastrulation, which are regulated by numerous signaling pathways, such as the Wnt (Wingless/Integrated), Notch, and FGF (Fibroblast growth factor) pathways. However, the coordination of the Notch and FGF signaling pathways during gastrulation remains unclear. We identified a novel helix–loop–helix DNA binding domain gene (Hes5.9), which was regulated by the FGF and Notch signaling pathways during gastrulation. Furthermore, gain- and loss-of-function of Hes5.9 led to defective cell migration and disturbed the expression patterns of mesodermal and endodermal marker genes, thus interfering with gastrulation. Collectively, these results suggest that Hes5.9 plays a crucial role in cell fate decisions and cell migration during gastrulation, which is modulated by the FGF and Notch signaling pathways.

Effects of Human Endothelial Progenitor Cell and Its Conditioned Medium on Oocyte Development and Subsequent Embryo Development

Human endothelial progenitor cells (EPCs) secrete numerous growth factors, and they have been applied to regenerative medicine for their roles in angiogenesis as well as neovascularization. Angiogenesis is one of the essential factors for the maturation of ovarian follicles; however, the physiological function of EPCs or their derivatives on in vitro culture systems has not been fully understood. The aim of this study was to evaluate the effectiveness of EPCs and their conditioned medium (EPC-CM) on oocyte development and subsequent embryo development. In the results, the oocyte development and subsequent embryo development were significantly improved in EPCs and the EPC-CM group. In addition, markedly increased levels of growth factors/cytokines, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin growth factor-1 (IGF-1), interleukin-10 (IL-10), and epidermal growth factor (EGF), were observed in medium from the EPC-CM group. Additionally, EPC-CM after in vitro maturation (IVM) had significantly decreased reactive oxygen species (ROS) levels compared to those of other groups. Transcriptional levels of growth factor receptor-related genes (FGFR2, IGF1R) and anti-apoptotic-related gene (BCL2) were significantly upregulated in cumulus cells/oocytes from the EPC-CM group compared with those from the control. Furthermore, the expression levels of cumulus expansion-related genes (PTGS2, TNFAIP6, HAS2) and oocyte-maturation-related factors (GDF9, BMP15) were significantly enhanced in the EPC-CM group. Consequently, the present study provides the first evidence that EPC-CM contains several essential growth factors for oocyte development by regulating genes involved in oocyte maturation.

Prospects of circadian clock in joint cartilage development

Altering the food intake, exercise, and sleep patterns have a great influence on the homeostasis of the biological clock. This leads to accelerated aging of the articular cartilage, susceptibility to arthropathy and other aspects. Deficiency or overexpression of certain circadian clock-related genes accelerates the cartilage deterioration and leads to phenotypic variation in different joints. The process of joint cartilage development includes the formation of joint site, interzone, joint cavitation, epiphyseal ossification center, and cartilage maturation. The mechanism by which, biological clock regulates the cell-cycle, growth, metabolism, and other biological processes of chondrocytes is poorly understood. Here, we summarized the interaction between biological clock proteins and developmental pathways in chondrogenesis and provided the evidence from other tissues that further predicts the molecular patterns of these protein-protein networks in activation, proliferation, and differentiation. The purpose of this review is to gain deeper understanding of the evolution of cartilage and its irreversibility seen in damage and aging.

Polysialylation and disease

Polysialic acid (polySia, PSA) is a unique constituent of the glycocalyx on the surface of bacterial and vertebrate cells. In vertebrates, its biosynthesis is highly regulated, not only in quantity and quality, but also in time and location, which allows polySia to be involved in various important biological phenomena. Therefore, impairments in the expression and structure of polySia sometimes relate to diseases, such as schizophrenia, bipolar disorder, and cancer. Some bacteria express polySia as a tool for protecting themselves from the host immune system during invasion. PolySia is proven to be a biosafe material; polySia, as well as polySia-recognizing molecules, are key therapeutic agents. This review first comprehensive outlines the occurrence, features, biosynthesis, and functions of polySia and subsequently focuses on the related diseases.

Adipose-derived stem cells: An appropriate selection for osteogenic differentiation

Mesenchymal stem cells (MSCs) are a major component of various forms of tissue engineering. MSCs have self-renewal and multidifferential potential. Osteogenic differentiation of MSCs is an area of attention in bone regeneration. One form of MSCs are adipose-derived stem cells (ASCs), which can be simply harvested and differentiated into several cell lineages, such as chondrocytes, adipocytes, or osteoblasts. Due to special properties, ASCs are frequently used in vitro and in vivo bone regeneration. Identifying factors involved in osteogenic differentiation of ASCs is important for better understanding the mechanism of osteogenic differentiation. Different methods are used to stimulate osteogenesis of ASCs in literature, including common osteogenic media, growth factors, hormones, hypoxia, mechanical and chemical stimuli, genetic modification, and nanotechnology. This review article provides an overview describing the isolation procedure, characterization, properties, current methods for osteogenic differentiation of ASCs, and their basic biological mechanism.

Environmental epigenetics and epigenetic inheritance in domestic farm animals

Epigenetics refers to molecular factors and processes around DNA that can affect genome activity and gene expression independent of DNA sequence. Epigenetic mechanisms drive developmental processes and have also been shown to be tied to disease development. Many epigenetic studies have been done using plants, rodent, and human models, but fewer have focused on domestic livestock species. The goal of this review is to present current epigenetic findings in livestock species (cattle, pigs, sheep and poultry). Much of this research examined epigenetic effects following exposure to toxicants, nutritional changes or infectious disease in those animals directly exposed, or in the offspring they produced. A limited number of studies in domestic animals have examined epigenetic transgenerational inheritance in the absence of continued exposures. One example used a porcine model to investigate the effect that feeding males a diet supplemented with micronutrients had on liver DNA methylation and muscle mass in grand-offspring (the transgenerational F2 generation). Further research into how epigenetic mechanisms affect the health and production traits of domestic livestock and their offspring is important to elucidate.

Role of FGF10/FGFR2b Signaling in Mouse Digestive Tract Development, Repair and Regeneration Following Injury

During embryonic development, the rudimentary digestive tract is initially a tube-like structure. It is composed of epithelial cells surrounded by mesenchymal cells. Reciprocal epithelial–mesenchymal interactions progressively subdivide this primitive tube into distinct functional regions: the tongue, the pharynx, the esophagus, the stomach, the duodenum, the small intestine, the cecum, the large intestine, the colon, and the anus as well as the pancreas and the liver. Fibroblast growth factors (Fgfs) constitute a family of conserved small proteins playing crucial roles during organogenesis, homeostasis, and repair after injury. Among them, fibroblast growth factor 10 (Fgf10) has been reported to orchestrate epithelial–mesenchymal interactions during digestive tract development. In mice, loss of function of Fgf10 as well as its receptor fibroblast growth factor receptor 2b (Fgfr2b) lead to defective taste papillae in the tongue, underdeveloped and defective differentiation of the stomach, duodenal, cecal, and colonic atresias, anorectal malformation, as well as underdeveloped pancreas and liver. Fgf signaling through Fgfr2b receptor is also critical for the repair process after gut injury. In the adult mice, a malabsorption disorder called small bowel syndrome is triggered after massive small bowel resection (SBR). In wild-type mice, SBR leads to a regenerative process called gut adaptation characterized by an increase in the diameter of the remaining small intestine as well as by the presence of deeper crypts and longer villi, altogether leading to increased intestinal surface. Intestinal stem cells are key for this regeneration process. Induction of Fgf10 expression in the Paneth cells located in the crypt following SBR suggests a critical role for this growth factor in the process of gut adaptation.

The Role of Fibroblast Growth Factor 23 in Inflammation and Anemia

In patients with chronic kidney disease (CKD), adverse outcomes such as systemic inflammation and anemia are contributing pathologies which increase the risks for cardiovascular mortality. Amongst these complications, abnormalities in mineral metabolism and the metabolic milieu are associated with chronic inflammation and iron dysregulation, and fibroblast growth factor 23 (FGF23) is a risk factor in this context. FGF23 is a bone-derived hormone that is essential for regulating vitamin D and phosphate homeostasis. In the early stages of CKD, serum FGF23 levels rise 1000-fold above normal values in an attempt to maintain normal phosphate levels. Despite this compensatory action, clinical CKD studies have demonstrated powerful and dose-dependent associations between FGF23 levels and higher risks for mortality. A prospective pathomechanism coupling elevated serum FGF23 levels with CKD-associated anemia and cardiovascular injury is its strong association with chronic inflammation. In this review, we will examine the current experimental and clinical evidence regarding the role of FGF23 in renal physiology as well as in the pathophysiology of CKD with an emphasis on chronic inflammation and anemia.

Circadian Vision in Zebrafish: From Molecule to Cell and from Neural Network to Behavior

Most visual system functions, such as opsin gene expression, retinal neural transmission, light perception, and visual sensitivity, display robust day-night rhythms. The rhythms persist in constant lighting conditions, suggesting the involvement of endogenous circadian clocks. While the circadian pacemakers that control the rhythms of animal behaviors are mostly found in the forebrain and midbrain, self-sustained circadian oscillators are also present in the neural retina, where they play important roles in the regulation of circadian vision. This review highlights some of the correlative studies of the circadian control of visual system functions in zebrafish. Because zebrafish maintain a high evolutionary proximity to mammals, the findings from zebrafish research may provide insights for a better understanding of the mechanisms of circadian vision in other vertebrate species including humans.

Bioinformatics prediction and analysis of hub genes and pathways of three types of gynecological cancer

Cervical, endometrial and vulvar cancer are three common types of gynecological tumor that threaten the health of females worldwide. Since their underlying mechanisms and associations remain unclear, a comprehensive and systematic bioinformatics analysis is required. The present study downloaded GSE63678 from the GEO database and then performed functional enrichment analyses, including gene ontology and pathway analysis. To further investigate the molecular mechanisms underlying the three types of gynecological cancer, protein-protein interaction (PPI) analysis was performed. A biological network was generated with the guidance of the Kyoto Encyclopedia of Genes and Genomes database and was presented in Cytoscape. A total of 1,219 DEGs were identified for the three types of cancer, and 25 hub genes were revealed. Pathway analysis and the PPI network indicated that four main types of pathway participate in the mechanism of gynecological cancer, including viral infections and cancer formation, tumorigenesis and development, signal transduction, and endocrinology and metabolism. A preliminary gynecological cancer biological network was constructed. Notably, following all analysis, the phosphoinositide 3-kinase (PI3K)/Akt pathway was identified as a potential biomarker pathway. Seven pivotal hub genes (CCNA2, CDK1, CCND1, FGF2, IGF1, BCL2 and VEGFA) of the three gynecological cancer types were proposed. The seven hub genes may serve as targets in gynecological cancer for prevention and early intervention. The PI3K/Akt pathway was identified as a critical biomarker of the three types of gynecological cancer, which may serve a role in the pathogenesis. In summary, the present study provided evidence that could support the treatment of gynecologic tumors in the future.

Fgf3 is crucial for the generation of monoaminergic cerebrospinal fluid contacting cells in zebrafish

In most vertebrates, including zebrafish, the hypothalamic serotonergic cerebrospinal fluid-contacting (CSF-c) cells constitute a prominent population. In contrast to the hindbrain serotonergic neurons, little is known about the development and function of these cells. Here, we identify fibroblast growth factor (Fgf)3 as the main Fgf ligand controlling the ontogeny of serotonergic CSF-c cells. We show that fgf3 positively regulates the number of serotonergic CSF-c cells, as well as a subset of dopaminergic and neuroendocrine cells in the posterior hypothalamus via control of proliferation and cell survival. Further, expression of the ETS-domain transcription factor etv5b is downregulated after fgf3 impairment. Previous findings identified etv5b as critical for the proliferation of serotonergic progenitors in the hypothalamus, and therefore we now suggest that Fgf3 acts via etv5b during early development to ultimately control the number of mature serotonergic CSF-c cells. Moreover, our analysis of the developing hypothalamic transcriptome shows that the expression of fgf3 is upregulated upon fgf3 loss-of-function, suggesting activation of a self-compensatory mechanism. Together, these results highlight Fgf3 in a novel context as part of a signalling pathway of critical importance for hypothalamic development.

Summary: This study highlights Fgf3 in a novel context where it is part of a signalling pathway of critical importance for development of hypothalamic monoaminergic cells in zebrafish.

A phase Ib study of GSK3052230, an FGF ligand trap in combination with pemetrexed and cisplatin in patients with malignant pleural mesothelioma

Background Fibroblast growth factors (FGFs) have a fundamental role in cancer. Sequestering FGFs with GSK3052230 (FP-1039) blocks their ability to activate FGFRs while avoiding toxicities associated with small molecule inhibitors of FGFR, including hyperphosphatemia and retinal, nail, and skin toxicities. Methods A multicenter, open-label, phase Ib study evaluated weekly GSK3052230 added to pemetrexed/cisplatin in patients with treatment-naive, unresectable malignant pleural mesothelioma. Doses were escalated according to a 3 + 3 design, followed by cohort expansion at the maximum tolerated dose (MTD). Endpoints included safety, overall response rate, progression-free survival, and pharmacokinetics. Results 36 patients were dosed at 10, 15, and 20 mg/kg doses of GSK3052230. Three dose-limiting toxicities were observed at 20 mg/kg and one at 15 mg/kg. The MTD was defined as 15 mg/kg and used for cohort expansion. The most common treatment-related adverse events (AEs) were nausea (56%), decreased appetite (36%), infusion reactions (36%), decreased neutrophil counts (36%), and fatigue (33%). The confirmed ORR was 39% (95% CI: 23.1-56.5) (14/36 PRs) and 47% had stable disease (17/36), giving a disease control rate of 86%. At 15 mg/kg GSK3052230 (n = 25), the ORR was 44% (95% CI: 24.4-65.1), and the median PFS was 7.4 months (95% CI: 6.7-13.4). Four patients had disease control for over 1 year, and three were still ongoing. Conclusion At 15 mg/kg weekly, GSK3052230 was well tolerated in combination with pemetrexed/cisplatin and durable responses were observed. Importantly, AEs associated with small molecule inhibitors of FGFR were not observed, as predicted by the unique mechanism of action of this drug.

Effects of transplantation of FGF-2-transfected MSCs and XACB on TNF-α expression with avascular necrosis of the femoral head in rabbits

Objective: The present study aimed to investigate the effect of the transplantation of basic fibroblast growth factor (FGF-2) gene-transfected mesenchymal stem cells (MSCs) and xenogeneic antigen-cancellous bone (XACB) on tumor necrosis factor-α (TNF-α) expression with avascular necrosis of the femoral head (ANFH) in rabbits. Methods: The models of steroid-induced osteonecrosis in rabbits were randomly divided into five groups: A (model), B (XACB), C (XACB + MSCs), D (XACB + MSCs + LV), and E (XACB + MSCs + LV-FGF-2) groups. The therapeutic effect was evaluated by Hematoxylin and Eosin (H&E) staining. Immunohistochemical and RT-PCR assays were used to detect the protein and mRNA expression of TNF-α in the femoral head, respectively. Results: At 12 weeks after the operation, the defect in rabbits in group E was completely repaired, while defects in rabbits in the other groups were not completely repaired, and the area of new bone formation was higher, when compared with the other groups (P<0.05). Furthermore, the protein and mRNA expression TNF-α was lower at 3, 6, and 12 weeks after surgery, when compared with the other groups, and the difference was statistically significant (P<0.05). Conclusion: FGF-2/MSCs/XACB could promote the repair of ANFH, and may be correlated to the inhibition of TNF-α expression.

Sialic Acids in Neurology

Sialic acid (Sia) is involved in many biological activities and commonly occurs as a monosialyl residue at the nonreducing terminal end of glycoconjugates. The loss of activity of UDP-GlcNAc2-epimerase/ManNAc kinase, which is a key enzyme in Sia biosynthesis, is lethal to the embryo, which clearly indicates the importance of Sia in embryogenesis. Occasionally, oligo/polymeric Sia structures such as disialic acid (diSia), oligosialic acid (oligoSia), and polysialic acid (polySia) occur in glycoconjugates. In particular, polySia, a well-known epitope that commonly occurs in neuroinvasive bacteria and vertebrate brains, is one of the most well-known and biologically/neurologically important glycotopes in vertebrates. The biological effects of polySia, especially on neural cell-adhesion molecules, have been well studied, and in-depth knowledge regarding polySia has been accumulated. In addition, the importance of diSia and oligoSia epitopes has been reported. In this chapter, the recent advances in the study of diSia, oligoSia, and polySia residues in glycoproteins in neurology, and their history, definition, occurrence, analytical methods, biosynthesis, and biological functions evaluated by phenotypes of gene-targeted mice, biochemical features, and related diseases are described.

Inhibition of FGF/FGFR autocrine signaling in mesothelioma with the FGF ligand trap, FP-1039/GSK3052230

Fibroblast growth factor (FGF) ligand-dependent signaling has a fundamental role in cancer development and tumor maintenance. GSK3052230 (also known as FP-1039) is a soluble decoy receptor that sequesters FGFs and inhibits FGFR signaling. Herein, the efficacy of this molecule was tested in models of mesothelioma, a tumor type shown to express high levels of FGF2 and FGFR1. GSK3052230 demonstrated antiproliferative activity across a panel of mesothelioma cell lines and inhibited growth of tumor xenografts in mice. High expression of FGF2 and FGFR1 correlated well with response to FGF pathway inhibition. GSK3052230 inhibited MAPK signaling as evidenced by decreased phospho-ERK and phospho-S6 levels in vitro and in vivo. Additionally, dose-dependent and statistically-significant reductions in tumor vessel density were observed in GSK3052230-treated tumors compared to vehicle-treated tumors. These data support the role of GSK3052230 in effectively targeting FGF-FGFR autocrine signaling in mesothelioma, demonstrate its impact on tumor growth and angiogenesis, and provide a rationale for the current clinical evaluation of this molecule in mesothelioma patients.

[Molecular biological markers for proliferation, apoptosis, and angiogenesis in diffuse toxic goiter]

The pathogenesis of diffuse toxic goiter has not yet been fully understood. The literature increasing commonly focusses on the issues related to the processes occurring in the thyroid gland itself: proliferation, apoptosis, and angiogenesis.

AIM

to investigate clinical and laboratory parameters, as well as the expression of Ki-67, Bcl-2, Bax, Fas-L, CD34, VEGF, and FGF proteins in various postoperative outcomes of patients operated on for diffuse toxic goiter.

SUBJECTS AND METHODS

The investigation enrolled 24 women who had undergone surgery using the technique described by E.S. Drachinskaya. Immunohistochemical tests were carried out according to the standard protocol. The expression of Ki-67, Bcl-2, Bax, Fas-L, CD 34, VEGF, angiopoietin, and FGF proteins was determined.

RESULTS

The patients with postoperative thyrotoxicosis were ascertained to have a significantly greater expression of anti-apoptotic protein Bcl-2, proliferation marker Ki-67, vascular factors (FGF, VEGF), and CD 34.

CONCLUSION

The relative expression area of the anti-apoptotic protein Bcl-2 of more than 2.19 or the proliferation protein Ki-67 of more than 1.059 was found to predict the development of postoperative thyrotoxicosis with an accuracy of higher than 85%.

Omics and cytokine discovery in fish: Presenting the Yellowtail kingfish (Seriola lalandi) as a case study

A continued programme of research is essential to overcome production bottlenecks in any aquacultured fish species. Since the introduction of genetic and molecular techniques, the quality of immune research undertaken in fish has greatly improved. Thousands of species specific cytokine genes have been discovered, which can be used to conduct more sensitive studies to understand how fish physiology is affected by aquaculture environments or disease. Newly available transcriptomic technologies, make it increasingly easier to study the immunogenetics of farmed species for which little data exists. This paper reviews how the application of transcriptomic procedures such as RNA Sequencing (RNA-Seq) can advance fish research. As a case study, we present some preliminary findings using RNA-Seq to identify cytokine related genes in Seriola lalandi. These will allow in-depth investigations to understand the immune responses of these fish in response to environmental change or disease and help in the development of therapeutic approaches.

Effect of Fetal Mouse Lung Tissue Co-Culture on In Vitro Maturation of Mouse Immature Oocytes

OBJECTIVES

The aim of this study was to evaluate the fetal mouse lung tissue co-culture on in vitro maturation (IVM) of mouse immature oocytes.

MATERIALS AND METHODS

In this experimental study, germinal vesicle (GV) oocytes from ovaries of a group of 25 female mice, 6-8 weeks of age, were dissected after being stimulated by 7.5 IU pregnant mare serum gonadotropin (PMSG) through an intraperitoneal (IP) injection. The fetal lung tissues were then prepared and cultured individually. A total number of 300 oocytes were cultured in the following three groups for 24 hours: control group (n=100) containing only base medium, group I (n=100) containing base medium co-cultured with 11.5- to 12.5-day old fetal mouse lung tissues, and group II (n=100) containing base medium co-cultured with 12.5- to 13.5-day old fetal mouse lung tissues. The proportion of GV and metaphase І (MI) oocytes matured into MІІ oocytes were compared among the three groups using analysis of variance (ANOVA). Correlation test were also used to evaluate the successful rate of IVM oocytes.

RESULTS

The proportions of GV oocytes reaching MІІ stage were 46, 65, and 56%, in control, I and II groups, respectively (P<0.05). The percentage of the oocytes remaining at the GV stage were higher in control group as compared with two treatment groups (P<0.05).

CONCLUSIONS

This study indicated that fetal mouse lung tissue co-culture method increased the percentage of GV oocytes reaching MII stage.

Role of fibroblast growth factors in bone regeneration

Bone is a metabolically active organ that undergoes continuous remodeling throughout life. However, many complex skeletal defects such as large traumatic bone defects or extensive bone loss after tumor resection may cause failure of bone healing. Effective therapies for these conditions typically employ combinations of cells, scaffolds, and bioactive factors. In this review, we pay attention to one of the three factors required for regeneration of bone, bioactive factors, especially the fibroblast growth factor (FGF) family. This family is composed of 22 members and associated with various biological functions including skeletal formation. Based on the phenotypes of genetically modified mice and spatio-temporal expression levels during bone fracture healing, FGF2, FGF9, and FGF18 are regarded as possible candidates useful for bone regeneration. The role of these candidate FGFs in bone regeneration is also discussed in this review.

LncRNA-MALAT1 Promotes Angiogenesis of Thyroid Cancer by Modulating Tumor-Associated Macrophage FGF2 Protein Secretion

Tumor-associated macrophages (TAMs) in the tumor microenvironment have been associated with enhanced tumor progression. In this study, we investigated the role and molecular mechanisms of MALAT1 in TAMs derived from thyroid cancer. The expression of MALAT1 and FGF2 in thyroid cancer tissues and cells were measured by quantitative real-time PCR and Western blot. TAMs were transfected with indicated constructs. Then the culture medium (CM) from TAMs was harvested for assay. Secreted FGF2 protein levels and TNF-α, IL-12, and IL-10 levels were detected by ELISA. The cell proliferation, migration, and invasion of FTC133 cells were determined with a CCK-8 assay and a Transwell assay, respectively. In addition, HUVEC vasculature formation was measured by matrigel angiogenesis assay. The higher levels of MALAT-1 and FGF2 were observed in thyroid cancer tissues and in thyroid cancer cells compared to that in the control. Besides, in the presence of si-MALAT1, the levels of TNF-α and IL-12 were significantly up-regulated whereas IL-10 was down-regulated in the CM from TAMs. Moreover, down-regulation of MALAT1 in TAMs reduced proliferation, migration, and invasion of FTC133 cells and inhibited angiogenesis. However, overexpression of FGF2 blocked the effects of MALAT1 siRNAs on cell migration, invasion, and angiogenesis. Our results suggest that MALAT1-mediated FGF2 protein secretion from TAMs inhibits inflammatory cytokines release, promotes proliferation, migration, and invasion of FTC133 cells and induces vasculature formation. J. Cell. Biochem. 118: 4821-4830, 2017. © 2017 Wiley Periodicals, Inc.

Fibroblast Growth Factors in the Gastrointestinal Tract: Twists and Turns

Fibroblast growth factors (FGFs) are a family of conserved peptides that play an important role in the development, homeostasis, and repair processes of many organ systems, including the gastrointestinal tract. All four FGF receptors and several FGF ligands are present in the intestine. They play important roles in controlling cell proliferation, differentiation, epithelial cell restitution, and stem cell maintenance. Several FGFs have also been proven to be protective against gastrointestinal diseases such as inflammatory bowel diseases or to aid in regeneration after intestinal loss associated with short bowel syndrome. Herein, we review the multifaceted actions of canonical FGFs in intestinal development, homeostasis, and repair in rodents and humans. Developmental Dynamics 246:344-352, 2017. © 2016 Wiley Periodicals, Inc.

Genetic insights into the mechanisms of Fgf signaling

The fibroblast growth factor (Fgf) family of ligands and receptor tyrosine kinases is required throughout embryonic and postnatal development and also regulates multiple homeostatic functions in the adult. Here, Brewer et al. review the mechanisms of Fgf signaling by focusing on genetic strategies that enable in vivo analysis.

The fibroblast growth factor (Fgf) family of ligands and receptor tyrosine kinases is required throughout embryonic and postnatal development and also regulates multiple homeostatic functions in the adult. Aberrant Fgf signaling causes many congenital disorders and underlies multiple forms of cancer. Understanding the mechanisms that govern Fgf signaling is therefore important to appreciate many aspects of Fgf biology and disease. Here we review the mechanisms of Fgf signaling by focusing on genetic strategies that enable in vivo analysis. These studies support an important role for Erk1/2 as a mediator of Fgf signaling in many biological processes but have also provided strong evidence for additional signaling pathways in transmitting Fgf signaling in vivo.

Fibroblast growth factor receptor signaling in hereditary and neoplastic disease: biologic and clinical implications

Fibroblast growth factors (FGFs) and their receptors (FGFRs) are transmembrane growth factor receptors with wide tissue distribution. FGF/FGFR signaling is involved in neoplastic behavior and also development, differentiation, growth, and survival. FGFR germline mutations (activating) can cause skeletal disorders, primarily dwarfism (generally mutations in FGFR3), and craniofacial malformation syndromes (usually mutations in FGFR1 and FGFR2); intriguingly, some of these activating FGFR mutations are also seen in human cancers. FGF/FGFR aberrations reported in cancers are mainly thought to be gain-of-function changes, and several cancers have high frequencies of FGFR alterations, including breast, bladder, or squamous cell carcinomas (lung and head and neck). FGF ligand aberrations (predominantly gene amplifications) are also frequently seen in cancers, in contrast to hereditary syndromes. There are several pharmacologic agents that have been or are being developed for inhibition of FGFR/FGF signaling. These include both highly selective inhibitors as well as multi-kinase inhibitors. Of note, only four agents (ponatinib, pazopanib, regorafenib, and recently lenvatinib) are FDA-approved for use in cancer, although the approval was not based on their activity against FGFR. Perturbations in the FGFR/FGF signaling are present in both inherited and malignant diseases. The development of potent inhibitors targeting FGF/FGFR may provide new tools against disorders caused by FGF/FGFR alterations.

Fgf regulates dedifferentiation during skeletal muscle regeneration in adult zebrafish

Fibroblast growth factors (Fgfs) regulate critical biological processes such as embryonic development, tissue homeostasis, wound healing, and tissue regeneration. In zebrafish, Fgf signaling plays an important role in the regeneration of the spinal cord, liver, heart, fin, and photoreceptors, although its exact mechanism of action is not fully understood. Utilizing an adult zebrafish extraocular muscle (EOM) regeneration model, we demonstrate that blocking Fgf receptor function using either a chemical inhibitor (SU5402) or a dominant-negative transgenic construct (dnFGFR1a:EGFP) impairs muscle regeneration. Adult zebrafish EOMs regenerate through a myocyte dedifferentiation process, which involves a muscle-to-mesenchyme transition and cell cycle reentry by differentiated myocytes. Blocking Fgf signaling reduced cell proliferation and active caspase 3 levels in the regenerating muscle with no detectable levels of apoptosis, supporting the hypothesis that Fgf signaling is involved in the early steps of dedifferentiation. Fgf signaling in regenerating myocytes involves the MAPK/ERK pathway: inhibition of MEK activity with U0126 mimicked the phenotype of the Fgf receptor inhibition on both muscle regeneration and cell proliferation, and activated ERK (p-ERK) was detected in injured muscles by immunofluorescence and western blot. Interestingly, following injury, ERK2 expression is specifically induced and activated by phosphorylation, suggesting a key role in muscle regeneration. We conclude that the critical early steps of myocyte dedifferentiation in EOM regeneration are dependent on Fgf signaling.

Genome-wide patterns of copy number variation in the Chinese yak genome

Background

Copy number variation (CNV) represents an important source of genetic divergence that can produce drastic phenotypic differences and may therefore be subject to selection during domestication and environmental adaptation. To investigate the evolutionary dynamics of CNV in the yak genome, we used a read depth approach to detect CNV based on genome resequencing data from 14 wild and 65 domestic yaks and determined CNV regions related to domestication and adaptations to high-altitude.

Results

We identified 2,634 CNV regions (CNVRs) comprising a total of 153 megabases (5.7 % of the yak genome) and 3,879 overlapping annotated genes. Comparison between domestic and wild yak populations identified 121 potentially selected CNVRs, harboring genes related to neuronal development, reproduction, nutrition and energy metabolism. In addition, we found 85 CNVRs that are significantly different between domestic yak living in high- and low-altitude areas, including three genes related to hypoxia response and six related to immune defense. This analysis shows that genic CNVs may play an important role in phenotypic changes during yak domestication and adaptation to life at high-altitude.

Conclusions

We present the first refined CNV map for yak along with comprehensive genomic analysis of yak CNV. Our results provide new insights into the genetic basis of yak domestication and adaptation to living in a high-altitude environment, as well as a valuable genetic resource that will facilitate future CNV association studies of important traits in yak and other bovid species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2702-6) contains supplementary material, which is available to authorized users.

An Fgf-Shh signaling hierarchy regulates early specification of the zebrafish skull

The neurocranium generates most of the craniofacial skeleton and consists of prechordal and postchordal regions. Although development of the prechordal is well studied, little is known of the postchordal region. Here we characterize a signaling hierarchy necessary for postchordal neurocranial development involving Fibroblast growth factor (Fgf) signaling for early specification of mesodermally-derived progenitor cells. The expression of hyaluron synthetase 2 (has2) in the cephalic mesoderm requires Fgf signaling and Has2 function, in turn, is required for postchordal neurocranial development. While Hedgehog (Hh)-deficient embryos also lack a postchordal neurocranium, this appears primarily due to a later defect in chondrocyte differentiation. Inhibitor studies demonstrate that postchordal neurocranial development requires early Fgf and later Hh signaling. Collectively, our results provide a mechanistic understanding of early postchordal neurocranial development and demonstrate a hierarchy of signaling between Fgf and Hh in the development of this structure.