651
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Han D, Zhao H, Parada C, Hacia JG, Bringas P, Chai Y. A TGFβ-Smad4-Fgf6 signaling cascade controls myogenic differentiation and myoblast fusion during tongue development. Development 2012; 139:1640-50. [PMID: 22438570 DOI: 10.1242/dev.076653] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The tongue is a muscular organ and plays a crucial role in speech, deglutition and taste. Despite the important physiological functions of the tongue, little is known about the regulatory mechanisms of tongue muscle development. TGFβ family members play important roles in regulating myogenesis, but the functional significance of Smad-dependent TGFβ signaling in regulating tongue skeletal muscle development remains unclear. In this study, we have investigated Smad4-mediated TGFβ signaling in the development of occipital somite-derived myogenic progenitors during tongue morphogenesis through tissue-specific inactivation of Smad4 (using Myf5-Cre;Smad4(flox/flox) mice). During the initiation of tongue development, cranial neural crest (CNC) cells occupy the tongue buds before myogenic progenitors migrate into the tongue primordium, suggesting that CNC cells play an instructive role in guiding tongue muscle development. Moreover, ablation of Smad4 results in defects in myogenic terminal differentiation and myoblast fusion. Despite compromised muscle differentiation, tendon formation appears unaffected in the tongue of Myf5-Cre;Smad4(flox/flox) mice, suggesting that the differentiation and maintenance of CNC-derived tendon cells are independent of Smad4-mediated signaling in myogenic cells in the tongue. Furthermore, loss of Smad4 results in a significant reduction in expression of several members of the FGF family, including Fgf6 and Fgfr4. Exogenous Fgf6 partially rescues the tongue myoblast fusion defect of Myf5-Cre;Smad4(flox/flox) mice. Taken together, our study demonstrates that a TGFβ-Smad4-Fgf6 signaling cascade plays a crucial role in myogenic cell fate determination and lineage progression during tongue myogenesis.
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Affiliation(s)
- Dong Han
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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652
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Brooks AN, Kilgour E, Smith PD. Molecular pathways: fibroblast growth factor signaling: a new therapeutic opportunity in cancer. Clin Cancer Res 2012; 18:1855-62. [PMID: 22388515 DOI: 10.1158/1078-0432.ccr-11-0699] [Citation(s) in RCA: 312] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) signaling axis plays an important role in normal organ, vascular, and skeletal development. Deregulation of FGFR signaling through genetic modification or overexpression of the receptors (or their ligands) has been observed in numerous tumor settings, whereas the FGF/FGFR axis also plays a key role in driving tumor angiogenesis. A growing body of preclinical data shows that inhibition of FGFR signaling can result in antiproliferative and/or proapoptotic effects, both in vitro and in vivo, thus confirming the validity of the FGF/FGFR axis as a potential therapeutic target. In the past, development of therapeutic approaches to target this axis has been hampered by our inability to develop FGFR-selective agents. With the advent of a number of new modalities for selectively inhibiting FGF/FGFR signaling, we are now in a unique position to test and validate clinically the many hypotheses that have been generated preclinically.
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Affiliation(s)
- A Nigel Brooks
- Oncology Innovative Medicines, AstraZeneca, Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK
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653
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Abstract
The aging process decreases tissue function and regenerative capacity, which has been associated with cellular senescence and a decline in adult or somatic stem cell numbers and self-renewal within multiple tissues. The potential therapeutic application of stem cells to reduce the burden of aging and stimulate tissue regeneration after trauma is very promising. Much research is currently ongoing to identify the factors and molecular mediators of stem cell self-renewal to reach these goals. Over the last two decades, fibroblast growth factors (FGFs) and their receptors (FGFRs) have stood up as major players in both embryonic development and tissue repair. Moreover, many studies point to somatic stem cells as major targets of FGF signaling in both tissue homeostasis and repair. FGFs appear to promote self-renewing proliferation and inhibit cellular senescence in nearly all tissues tested to date. Here we review the role of FGFs and FGFRs in stem cell self-renewal, cellular senescence, and aging.
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Affiliation(s)
- Daniel L Coutu
- Stem Cell Dynamics Research Unit, Helmholtz Zentrum München, Munich, Germany
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654
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Choi SK, Yoon SR, Calabrese P, Arnheim N. Positive selection for new disease mutations in the human germline: evidence from the heritable cancer syndrome multiple endocrine neoplasia type 2B. PLoS Genet 2012; 8:e1002420. [PMID: 22359510 PMCID: PMC3280958 DOI: 10.1371/journal.pgen.1002420] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 10/19/2011] [Indexed: 01/15/2023] Open
Abstract
Multiple endocrine neoplasia type 2B (MEN2B) is a highly aggressive thyroid cancer syndrome. Since almost all sporadic cases are caused by the same nucleotide substitution in the RET proto-oncogene, the calculated disease incidence is 100-200 times greater than would be expected based on the genome average mutation frequency. In order to determine whether this increased incidence is due to an elevated mutation rate at this position (true mutation hot spot) or a selective advantage conferred on mutated spermatogonial stem cells, we studied the spatial distribution of the mutation in 14 human testes. In donors aged 36-68, mutations were clustered with small regions of each testis having mutation frequencies several orders of magnitude greater than the rest of the testis. In donors aged 19-23 mutations were almost non-existent, demonstrating that clusters in middle-aged donors grew during adulthood. Computational analysis showed that germline selection is the only plausible explanation. Testes of men aged 75-80 were heterogeneous with some like middle-aged and others like younger testes. Incorporating data on age-dependent death of spermatogonial stem cells explains the results from all age groups. Germline selection also explains MEN2B's male mutation bias and paternal age effect. Our discovery focuses attention on MEN2B as a model for understanding the genetic and biochemical basis of germline selection. Since RET function in mouse spermatogonial stem cells has been extensively studied, we are able to suggest that the MEN2B mutation provides a selective advantage by altering the PI3K/AKT and SFK signaling pathways. Mutations that are preferred in the germline but reduce the fitness of offspring increase the population's mutational load. Our approach is useful for studying other disease mutations with similar characteristics and could uncover additional germline selection pathways or identify true mutation hot spots.
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Affiliation(s)
- Soo-Kyung Choi
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California, United States of America
| | - Song-Ro Yoon
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California, United States of America
| | - Peter Calabrese
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California, United States of America
| | - Norman Arnheim
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California, United States of America
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655
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Role of the nuclear receptor coactivator AIB1/SRC-3 in angiogenesis and wound healing. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:1474-84. [PMID: 22342158 DOI: 10.1016/j.ajpath.2011.12.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 11/23/2011] [Accepted: 12/22/2011] [Indexed: 12/19/2022]
Abstract
The nuclear receptor coactivator amplified in breast cancer 1 (AIB1/SRC-3) has a well-defined role in steroid and growth factor signaling in cancer and normal epithelial cells. Less is known about its function in stromal cells, although AIB1/SRC-3 is up-regulated in tumor stroma and may, thus, contribute to tumor angiogenesis. Herein, we show that AIB1/SRC-3 depletion from cultured endothelial cells reduces their proliferation and motility in response to growth factors and prevents the formation of intact monolayers with tight junctions and of endothelial tubes. In AIB1/SRC-3(+/-) and (-/-) mice, the angiogenic responses to subcutaneous Matrigel implants was reduced by two-thirds, and exogenously added fibroblast growth factor (FGF) 2 did not overcome this deficiency. Furthermore, AIB1/SRC-3(+/-) and (-/-) mice showed similarly delayed healing of full-thickness excisional skin wounds, indicating that both alleles were required for proper tissue repair. Analysis of this defective wound healing showed reduced recruitment of inflammatory cells and macrophages, cytokine induction, and metalloprotease activity. Skin grafts from animals with different AIB1 genotypes and subsequent wounding of the grafts revealed that the defective healing was attributable to local factors and not to defective bone marrow responses. Indeed, wounds in AIB1(+/-) mice showed reduced expression of FGF10, FGFBP3, FGFR1, FGFR2b, and FGFR3, major local drivers of angiogenesis. We conclude that AIB1/SRC-3 modulates stromal cell responses via cross-talk with the FGF signaling pathway.
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656
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Abstract
Hair follicles repeatedly cycle through growth (anagen), regression (catagen), and resting (telogen) phases. Although the signaling molecules involved in the anagen and anagen-catagen transition have been studied extensively, the signaling that controls telogen is only partly understood. Here we show that fibroblast growth factor (Fgf)18 is expressed in a hair stem cell niche throughout telogen, and that it regulates the hair cycle through the non-growth phases. When the Fgf18 gene is conditionally knocked out in keratin 5-positive epithelial cells in mice, telogen becomes very short, giving rise to a strikingly rapid succession of hair cycles. In wild-type mice, hair follicle growth during anagen is strongly suppressed by local delivery of FGF18 protein. Our results demonstrate that epithelial FGF18 signaling and its reduction in the milieu of hair stem cells are crucial for the maintenance of resting and growth phase, respectively.
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657
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Huynh MB, Morin C, Carpentier G, Garcia-Filipe S, Talhas-Perret S, Barbier-Chassefière V, van Kuppevelt TH, Martelly I, Albanese P, Papy-Garcia D. Age-related changes in rat myocardium involve altered capacities of glycosaminoglycans to potentiate growth factor functions and heparan sulfate-altered sulfation. J Biol Chem 2012; 287:11363-73. [PMID: 22298772 DOI: 10.1074/jbc.m111.335901] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycosaminoglycans (GAGs) are essential components of the extracellular matrix, the natural environment from which cell behavior is regulated by a number or tissue homeostasis guarantors including growth factors. Because most heparin-binding growth factor activities are regulated by GAGs, structural and functional alterations of these polysaccharides may consequently affect the integrity of tissues during critical physiological and pathological processes. Here, we investigated whether the aging process can induce changes in the myocardial GAG composition in rats and whether these changes can affect the activities of particular heparin-binding growth factors known to sustain cardiac tissue integrity. Our results showed an age-dependent increase of GAG levels in the left ventricle. Biochemical and immunohistological studies pointed out heparan sulfates (HS) as the GAG species that increased with age. ELISA-based competition assays showed altered capacities of the aged myocardial GAGs to bind FGF-1, FGF-2, and VEGF but not HB EGF. Mitogenic assays in cultured cells showed an age-dependent decrease of the elderly GAG capacities to potentiate FGF-2 whereas the potentiating effect on VEGF(165) was increased, as confirmed by augmented angiogenic cell proliferation in Matrigel plugs. Moreover, HS disaccharide analysis showed considerably altered 6-O-sulfation with modest changes in N- and 2-O-sulfations. Together, these findings suggest a physiological significance of HS structural and functional alterations during aging. This can be associated with an age-dependent decline of the extracellular matrix capacity to efficiently modulate not only the activity of resident or therapeutic growth factors but also the homing of resident or therapeutic cells.
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Affiliation(s)
- Minh Bao Huynh
- Laboratoire Croissance, Reparation et Regeneration Tissulaires EAC/CNRS-7149, Université Paris Est Créteil, 94010 Créteil, France
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658
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Mu J, Pinkstaff J, Li Z, Skidmore L, Li N, Myler H, Dallas-Yang Q, Putnam AM, Yao J, Bussell S, Wu M, Norman TC, Rodriguez CG, Kimmel B, Metzger JM, Manibusan A, Lee D, Zaller DM, Zhang BB, DiMarchi RD, Berger JP, Axelrod DW. FGF21 analogs of sustained action enabled by orthogonal biosynthesis demonstrate enhanced antidiabetic pharmacology in rodents. Diabetes 2012; 61:505-12. [PMID: 22210323 PMCID: PMC3266413 DOI: 10.2337/db11-0838] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Fibroblast growth factor 21 (FGF21) mitigates many of the pathogenic features of type 2 diabetes, despite a short circulating half-life. PEGylation is a proven approach to prolonging the duration of action while enhancing biophysical solubility and stability. However, in the absence of a specific protein PEGylation site, chemical conjugation is inherently heterogeneous and commonly leads to dramatic loss in bioactivity. This work illustrates a novel means of specific PEGylation, producing FGF21 analogs with high specific activity and salutary biological activities. Using homology modeling and structure-based design, specific sites were chosen in human FGF21 for site-specific PEGylation to ensure that receptor binding regions were preserved. The in vitro activity of the PEGylated FGF21 ana-logs corresponded with the site of PEG placement within the binding model. Site-specific PEGylated analogs demonstrated dramatically increased circulating half-life and enhanced efficacy in db/db mice. Twice-weekly dosing of an optimal FGF21 analog reduced blood glucose, plasma lipids, liver triglycerides, and plasma glucagon and enhanced pancreatic insulin content, islet number, and glucose-dependent insulin secretion. Restoration of insulin sensitivity was demonstrated by the enhanced ability of insulin to induce Akt/protein kinase B phosphorylation in liver, muscle, and adipose tissues. PEGylation of human FGF21 at a specific and preferred site confers superior metabolic pharmacology.
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Affiliation(s)
- James Mu
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Jason Pinkstaff
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
- Corresponding author: Jason Pinkstaff,
| | - Zhihua Li
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Lillian Skidmore
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Nina Li
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Heather Myler
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Qing Dallas-Yang
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Anna-Maria Putnam
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Jun Yao
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Stuart Bussell
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Margaret Wu
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Thea C. Norman
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Carlos G. Rodriguez
- Department of In Vivo Pharmacology, Merck Research Laboratories, Rahway, New Jersey
| | - Bruce Kimmel
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Joseph M. Metzger
- Department of In Vivo Pharmacology, Merck Research Laboratories, Rahway, New Jersey
| | - Anthony Manibusan
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Darin Lee
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
| | - Dennis M. Zaller
- Department of External Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
| | - Bei B. Zhang
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | | | - Joel P. Berger
- Department of Metabolic Disease-Diabetes, Merck Research Laboratories, Rahway, New Jersey
| | - Douglas W. Axelrod
- Departments of Preclinical Sciences and Process Development, Ambrx Inc., La Jolla, California
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659
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Lee SA, Jeong E, Kim EH, Shin MS, Hwang JY, Koh EH, Lee WJ, Park JY, Kim MS. Various oscillation patterns of serum fibroblast growth factor 21 concentrations in healthy volunteers. Diabetes Metab J 2012; 36:29-36. [PMID: 22363919 PMCID: PMC3283824 DOI: 10.4093/dmj.2012.36.1.29] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 09/07/2011] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Fibroblast growth factor 21 (FGF21) was originally identified as a paroxysm proliferator activated receptor-α target gene product and is a hormone involved in metabolic regulation. The purpose of this study was to investigate the diurnal variation of serum FGF21 concentration in obese and non-obese healthy volunteers. METHODS Blood samples were collected from five non-obese (body mass index [BMI] ≤23 kg/m(2)) and five obese (BMI ≥25 kg/m(2)) healthy young men every 30 to 60 minutes over 24 hours. Serum FGF21 concentrations were determined by radioimmunoassay. Anthropometric parameters, glucose, free fatty acid, insulin, leptin, and cortisol concentrations were also measured. RESULTS The serum FGF21 concentrations displayed various individual oscillation patterns. The oscillation frequency ranged between 6 and 12 times per day. The average duration of oscillation was 2.52 hours (range, 1.9 to 3.0 hours). The peaks and troughs of FGF21 oscillation showed no circadian rhythm. However, the oscillation frequency had a diurnal variation and was lower during the light-off period than during the light-on period (2.4 vs. 7.3 times, P<0.001). There was no difference in the total frequency or duration of oscillations between non-obese and obese subjects, but obese individuals had increased numbers of larger oscillations (amplitude ≥0.19 ng/mL). CONCLUSION Various oscillation patterns in serum FGF21 concentration were observed, and reduced oscillation frequencies were seen during sleep. The oscillation patterns of serum FGF21 concentration suggest that FGF21 may be secreted into systemic circulation in a pulsatile manner. Obesity appeared to affect the amplitude of oscillations of serum FGF21.
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Affiliation(s)
- Sang Ah Lee
- Department of Internal Medicine, Jeju National University School of Medicine, Jeju, Korea
| | - Eunheiu Jeong
- Department of Internal Medicine, Seoul Veterans Hospital, Seoul, Korea
| | - Eun Hee Kim
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Mi-Seon Shin
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jenie Yoonoo Hwang
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Eun Hee Koh
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Woo Je Lee
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Joong-Yeol Park
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Min-Seon Kim
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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660
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Beenken A, Eliseenkova AV, Ibrahimi OA, Olsen SK, Mohammadi M. Plasticity in interactions of fibroblast growth factor 1 (FGF1) N terminus with FGF receptors underlies promiscuity of FGF1. J Biol Chem 2012; 287:3067-78. [PMID: 22057274 PMCID: PMC3270963 DOI: 10.1074/jbc.m111.275891] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 09/30/2011] [Indexed: 11/06/2022] Open
Abstract
Tissue-specific alternative splicing in the second half of Ig-like domain 3 (D3) of fibroblast growth factor receptors 1-3 (FGFR1 to -3) generates epithelial FGFR1b-FGFR3b and mesenchymal FGFR1c-FGFR3c splice isoforms. This splicing event establishes a selectivity filter to restrict the ligand binding specificity of FGFRb and FGFRc isoforms to mesenchymally and epithelially derived fibroblast growth factors (FGFs), respectively. FGF1 is termed the "universal FGFR ligand" because it overrides this specificity barrier. To elucidate the molecular basis for FGF1 cross-reactivity with the "b" and "c" splice isoforms of FGFRs, we determined the first crystal structure of FGF1 in complex with an FGFRb isoform, FGFR2b, at 2.1 Å resolution. Comparison of the FGF1-FGFR2b structure with the three previously published FGF1-FGFRc structures reveals that plasticity in the interactions of the N-terminal region of FGF1 with FGFR D3 is the main determinant of FGF1 cross-reactivity with both isoforms of FGFRs. In support of our structural data, we demonstrate that substitution of three N-terminal residues (Gly-19, His-25, and Phe-26) of FGF2 (a ligand that does not bind FGFR2b) for the corresponding residues of FGF1 (Phe-16, Asn-22, and Tyr-23) enables the FGF2 triple mutant to bind and activate FGFR2b. These findings taken together with our previous structural data on receptor binding specificity of FGF2, FGF8, and FGF10 conclusively show that sequence divergence at the N termini of FGFs is the primary regulator of the receptor binding specificity and promiscuity of FGFs.
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Affiliation(s)
- Andrew Beenken
- From the Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Anna V. Eliseenkova
- From the Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Omar A. Ibrahimi
- From the Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Shaun K. Olsen
- From the Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Moosa Mohammadi
- From the Department of Pharmacology, New York University School of Medicine, New York, New York 10016
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661
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Cheng AL, Shen YC, Zhu AX. Targeting fibroblast growth factor receptor signaling in hepatocellular carcinoma. Oncology 2012; 81:372-80. [PMID: 22269894 DOI: 10.1159/000335472] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 11/16/2011] [Indexed: 01/22/2023]
Abstract
Hepatocellular carcinoma (HCC) is the primary type of liver cancer, and both the age-adjusted incidence and mortality of HCC have steadily increased in recent years. Advanced HCC is associated with a very poor survival rate. Despite accumulating data regarding the risk factors for HCC, the mechanisms that contribute to HCC tumorigenesis remain poorly understood. Signaling through the fibroblast growth factor (FGF) family is involved in fibrosis and its progression to cirrhosis of the liver, which is a risk factor for the development of HCC. Furthermore, several alterations in FGF/FGF receptor (FGFR) signaling correlate with the outcomes of HCC patients, suggesting that signaling through this family of proteins contributes to the development or progression of HCC tumors. Currently, there are no established systemic treatments for patients with advanced HCC in whom sorafenib treatment has failed or who were unable to tolerate it. Recently, several multikinase inhibitors that target FGFRs have demonstrated some early evidence of antitumor activity in phase I/II trials. Therefore, this review discusses the molecular implications of FGFR-mediated signaling in HCC and summarizes the clinical evidence for novel FGFR-targeted therapies for HCC currently being studied in clinical trials.
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Affiliation(s)
- Ann-Lii Cheng
- Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan.
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662
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Ahmad I, Iwata T, Leung HY. Mechanisms of FGFR-mediated carcinogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:850-60. [PMID: 22273505 DOI: 10.1016/j.bbamcr.2012.01.004] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 01/09/2012] [Accepted: 01/10/2012] [Indexed: 12/11/2022]
Abstract
In this review, the evidence for a role of fibroblast growth factor receptor (FGFR) mediated signalling in carcinogenesis are considered and relevant underlying mechanisms highlighted. FGF signalling mediated by FGFR follows a classic receptor tyrosine kinase signalling pathway and its deregulation at various points of its cascade could result in malignancy. Here we review the accumulating reports that revealed the association of FGF/FGFRs to various types of cancer at a genetic level, along with in vitro and in vivo evidences available so far, which indicates the functional involvement of FGF signalling in tumour formation and progression. An increasing number of drugs against the FGF pathways is currently in clinical testing. We will discuss the strategies for future FGF research in cancer and translational approaches.
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Affiliation(s)
- Imran Ahmad
- Beatson Institute for Cancer Research, Bearsden, Glasgow G61 1BD, UK
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663
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Neural cell adhesion molecule differentially interacts with isoforms of the fibroblast growth factor receptor. Neuroreport 2012; 22:727-32. [PMID: 21876469 DOI: 10.1097/wnr.0b013e3283491682] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The fibroblast growth factor receptor (FGFR) can be activated through direct interactions with various fibroblast growth factors or through a number of cell adhesion molecules, including the neural cell adhesion molecule (NCAM). We produced recombinant proteins comprising the ligand-binding immunoglobulin-like modules 2 and 3 of FGFR1b, FGFR1c, FGFR2b, FGFR2c, FGFR3b, FGFR3c, and FGFR4, and found that all FGFR isoforms, except for FGFR4, interacted with NCAM. The binding affinity of NCAM-FGFR interactions was considerably higher for splice variant 'b' than for splice variant 'c'. We suggest that the expression pattern of various FGFR isoforms determines the cell context-specific effects of NCAM signaling through FGFR.
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664
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Singh R, Su J, Brooks J, Terauchi A, Umemori H, Fox MA. Fibroblast growth factor 22 contributes to the development of retinal nerve terminals in the dorsal lateral geniculate nucleus. Front Mol Neurosci 2012; 4:61. [PMID: 22363257 PMCID: PMC3306139 DOI: 10.3389/fnmol.2011.00061] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 12/23/2011] [Indexed: 11/28/2022] Open
Abstract
At least three forms of signaling between pre- and postsynaptic partners are necessary during synapse formation. First, “targeting” signals instruct presynaptic axons to recognize and adhere to the correct portion of a postsynaptic target cell. Second, trans-synaptic “organizing” signals induce differentiation in their synaptic partner so that each side of the synapse is specialized for synaptic transmission. Finally, in many regions of the nervous system an excess of synapses are initially formed, therefore “refinement” signals must either stabilize or destabilize the synapse to reinforce or eliminate connections, respectively. Because of both their importance in processing visual information and their accessibility, retinogeniculate synapses have served as a model for studying synaptic development. Molecular signals that drive retinogeniculate “targeting” and “refinement” have been identified, however, little is known about what “organizing” cues are necessary for the differentiation of retinal axons into presynaptic terminals. To identify such “organizing” cues, we used microarray analysis to assess whether any target-derived “synaptic organizers” were enriched in the mouse dorsal lateral geniculate nucleus (dLGN) during retinogeniculate synapse formation. One candidate “organizing” molecule enriched in perinatal dLGN was FGF22, a secreted cue that induces the formation of excitatory nerve terminals in muscle, hippocampus, and cerebellum. In FGF22 knockout mice, the development of retinal terminals in dLGN was impaired. Thus, FGF22 is an important “organizing” cue for the timely development of retinogeniculate synapses.
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Affiliation(s)
- Rishabh Singh
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center Richmond, VA, USA
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665
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Kadam S, Ghosh S, Stathopoulos A. Synchronous and symmetric migration of Drosophila caudal visceral mesoderm cells requires dual input by two FGF ligands. Development 2012; 139:699-708. [PMID: 22219352 DOI: 10.1242/dev.068791] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Caudal visceral mesoderm (CVM) cells migrate synchronously towards the anterior of the Drosophila embryo as two distinct groups located on each side of the body, in order to specify longitudinal muscles that ensheath the gut. Little is known about the molecular cues that guide cells along this path, the longest migration of embryogenesis, except that they closely associate with trunk visceral mesoderm (TVM). The expression of the fibroblast growth factor receptor (FGFR) heartless and its ligands, pyramus (pyr) and thisbe (ths), within CVM and TVM cells, respectively, suggested FGF signaling may influence CVM cell guidance. In FGF mutants, CVM cells die before reaching the anterior region of the TVM. However, an earlier phenotype observed was that the two cell clusters lose direction and converge at the midline. Live in vivo imaging and tracking analyses identified that the movements of CVM cells were slower and no longer synchronous. Moreover, CVM cells were found to cross over from one group to the other, disrupting bilateral symmetry, whereas such mixing was never observed in wild-type embryos. Ectopic expression of either Pyr or Ths was sufficient to redirect CVM cell movement, but only when the endogenous source of these ligands was absent. Collectively, our results show that FGF signaling regulates directional movement of CVM cells and that native presentation of both FGF ligands together is most effective at attracting cells. This study also has general implications, as it suggests that the activity supported by two FGF ligands in concert differs from their activities in isolation.
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Affiliation(s)
- Snehalata Kadam
- Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
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666
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Li K, Li L, Yang M, Liu H, Boden G, Yang G. The effects of fibroblast growth factor-21 knockdown and over-expression on its signaling pathway and glucose-lipid metabolism in vitro. Mol Cell Endocrinol 2012; 348:21-6. [PMID: 21801806 DOI: 10.1016/j.mce.2011.07.026] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 07/09/2011] [Accepted: 07/12/2011] [Indexed: 10/17/2022]
Abstract
OBJECTIVE The aim of this study was to examine the effects of FGF-21 over- and underexpression on glucose and lipid metabolism in hepatocytes and adipocytes. METHODS FGF-21 over-expressive vectors (pcDNA-FGF-21) and FGF-21 shRNA-expressing vectors (pGenesil-FGF-21) were transfected into Hepa1-6 hepatocyte and 3T3-L1 adipocyte. The levels of FGF-21 in the incubation medium were measured by ELISA. FGF-21 protein levels by Western blot analysis, and glucose uptake rates (GUR) by measuring 2-deoxy-d-glucose uptake. The mRNA expression of transcription factors were determined by real-time quantitative PCR. RESULTS Transfection of pcDNA-FGF-21 significantly increased FGF-21 expression in both Hepa1-6 hepatocytes and 3T3-L1 adipocytes (4.8- and 4.2-fold, respectively p<0.05), while transfection of pGenesil-FGF-21 significantly decreased FGF-21 expressions by 86% and 78%, respectively (p<0.05). In 3T3-L1 adipocytes, the up-regulation of FGF-21markedly increased GUR, decreased intracellular triglyceride (TG) content, up-regulated β-klotho, FGFR1, GLUT-1, IRS-1, ATGL, HSL, and ap2 mRNA expressions (p<0.05). Opposite changes occurred in FGF-21 knockdown adipocytes, except for IRS-1. In hepatocyte, FGF-21 up-regulation reduced HMGR and PEPCK mRNA expression and increased β-klotho, FGFR4 and LDLr expression (p<0.05), whereas down-regulation had the opposite effects. CONCLUSION These data suggest that both FGF-21 knockdown and over-expression led to changes in lipid levels, GUR and transcription factors involved in glucose and lipid metabolism, but that the mechanisms of FGF-21 actions in adipocytes and hepatocytes might be different.
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Affiliation(s)
- Ke Li
- Department of Endocrinology, The Second Affiliated Hospital, Chongqing Medical University, 400010 Chongqing, China
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667
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Abstract
Rodents and primates both show considerable variation in the overall size, the radial and tangential dimensions, folding and subdivisions into distinct areas of their cerebral cortex. Our current understanding of brain development is based on a handful of model systems. A detailed comparative analysis of the cellular and molecular mechanisms that regulate neural progenitor production, cell migration, and circuit assembly can provide much needed insights into the working of neocortical evolution. From the limited comparative data currently available, it is apparent that the emergence and variation of the neuronal progenitor cells have led to the production of increased neuronal populations and the evolution of the cortex. Further diversification and compartmentalization of the germinal zone together with changing proportions of radial glia in the ventricular zone and various intermediate progenitors in the subventricular zone may have been the driving force behind increased cell numbers in larger brains both in rodents and primates. Radial and tangential migratory patterns are both present in rodents and primates, but in different proportions. There are apparent differences between mouse and human in the generation and elaboration of the interneuronal subtypes and also in gene expression patterns associated with the appearance of distinct cortical areas. The increased cortical dimensions and the formation of a more elaborate cortical architecture in primates require a larger and more compartmentalized transient subplate zone during development. More comparative analysis in rodent and primate species with large, small, and smooth and folded brains is needed to reveal the biological significance of the alterations in these cortical developmental programs.
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668
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Understanding the structure-function relationship between FGF19 and its mitogenic and metabolic activities. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 728:195-213. [PMID: 22396171 DOI: 10.1007/978-1-4614-0887-1_13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
FGF19 differs from the classical FGFs in that it has a much-reduced heparan sulfate proteoglycan binding affinity that allows it to act as endocrine hormone. Although FGF19 regulates several different metabolic activities, it still activates downstream signaling pathways through FGF receptors, in a similar manner to that seen in classical FGFs. Aberrant FGF signaling has been implicated in tumor development, and mouse models have confirmed that FGF19 has the potential to induce hepatocellular carcinoma. Treatment with anti-FGF19 antibody suppressed tumor progression in both FGF19 transgenic mice and colon cancer cell xenograft models. FGFR4, the predominant FGF receptor expressed in the liver, may play an important role in FGF19-mediated tumorigenesis. This review reports the current advances in understanding the structure-function relationship between FGF19 and its interactions with FGFRs, its physiological activities, and its differences from FGF21. The review also discusses strategies to separate the mitogenic and metabolic activities for the development of potential therapeutic molecules based on FGF19.
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669
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Abstract
Fibroblast growth factors (FGFs) and their cognate receptors, FGF receptors (FGFRs), play critical roles in a variety of normal developmental and physiological processes. Numerous reports support a role for deregulation of FGF-FGFR signaling, whether it is at the ligand and/or receptor level, in tumor development and progression. The FGF19-FGFR4 signaling axis has been implicated in the pathogenesis of several cancers, including hepatocellular carcinomas in mice and potentially in humans. This chapter focuses on recent progress in the understanding of the molecular mechanisms of FGF19 action and its potential involvement in cancer.
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670
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Abstract
This chapter will review the various biological actions of the mouse fibroblast growth factor 15 (Fgf15) and human fibroblast growth factor 19 (FGF19). Unlike other members of the fibroblast growth factor (FGF) family, the Fgf15 and FGF19 orthologs do not share a high degree of sequence identity. Fgf15 and FGF19 are members of an atypical subfamily of FGFs that function as hormones. Due to subtle changes in tertiary structure, these FGFs have low heparin binding affinity enabling them to diffuse away from their site of secretion and signal to distant cells. FGF signaling through the FGF receptors is also different for this sub-family, requiring klotho protein cofactors rather than heparin sulfate proteoglycan. Mouse Fgf15 and human FGF19 play key roles in enterohepatic signaling, regulation of liver bile acid biosynthesis, gallbladder motility and metabolic homeostasis.
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671
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Abstract
Calcium (Ca(2+)) and phosphate (PO(4)(3-)) homeostasis are coordinated by systemic and local factors that regulate intestinal absorption, influx and efflux from bone, and kidney excretion and reabsorption of these ions through a complex hormonal network. Traditionally, the parathyroid hormone (PTH)/vitamin D axis provided the conceptual framework to understand mineral metabolism. PTH secreted by the parathyroid gland in response to hypocalcemia functions to maintain serum Ca(2+) levels by increasing Ca(2+) reabsorption and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] production by the kidney, enhancing Ca(2+) and PO(4)(3-) intestinal absorption and increasing Ca(2+) and PO(4)(3-) efflux from bone, while maintaining neutral phosphate balance through phosphaturic effects. FGF23 is a recently discovered hormone, predominately produced by osteoblasts/osteocytes, whose major functions are to inhibit renal tubular phosphate reabsorption and suppress circulating 1,25(OH)(2)D levels by decreasing Cyp27b1-mediated formation and stimulating Cyp24-mediated catabolism of 1,25(OH)(2)D. FGF23 participates in a new bone/kidney axis that protects the organism from excess vitamin D and coordinates renal PO(4)(3-) handling with bone mineralization/turnover. Abnormalities of FGF23 production underlie many inherited and acquired disorders of phosphate homeostasis. This review discusses the known and emerging functions of FGF23, its regulation in response to systemic and local signals, as well as the implications of FGF23 in different pathological and physiological contexts.
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Affiliation(s)
- Aline Martin
- University of Tennessee Health Science Center, Memphis, Tennessee, USA
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672
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Huh SH, Jones J, Warchol ME, Ornitz DM. Differentiation of the lateral compartment of the cochlea requires a temporally restricted FGF20 signal. PLoS Biol 2012; 10:e1001231. [PMID: 22235191 PMCID: PMC3250500 DOI: 10.1371/journal.pbio.1001231] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 11/18/2011] [Indexed: 12/11/2022] Open
Abstract
A large proportion of age-related hearing loss is caused by loss or damage to outer hair cells in the organ of Corti. The organ of Corti is the mechanosensory transducing apparatus in the inner ear and is composed of inner hair cells, outer hair cells, and highly specialized supporting cells. The mechanisms that regulate differentiation of inner and outer hair cells are not known. Here we report that fibroblast growth factor 20 (FGF20) is required for differentiation of cells in the lateral cochlear compartment (outer hair and supporting cells) within the organ of Corti during a specific developmental time. In the absence of FGF20, mice are deaf and lateral compartment cells remain undifferentiated, postmitotic, and unresponsive to Notch-dependent lateral inhibition. These studies identify developmentally distinct medial (inner hair and supporting cells) and lateral compartments in the developing organ of Corti. The viability and hearing loss in Fgf20 knockout mice suggest that FGF20 may also be a deafness-associated gene in humans.
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MESH Headings
- Animals
- Cell Differentiation/genetics
- Cochlea/cytology
- Cochlea/embryology
- Cochlea/metabolism
- Ear, Inner/cytology
- Ear, Inner/embryology
- Ear, Inner/metabolism
- Female
- Fibroblast Growth Factors/genetics
- Fibroblast Growth Factors/metabolism
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/metabolism
- Hearing Loss/genetics
- Hearing Loss/metabolism
- Humans
- Immunohistochemistry
- Male
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Organ Culture Techniques
- Organ of Corti/cytology
- Organ of Corti/embryology
- Organ of Corti/metabolism
- Receptors, Notch/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/genetics
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Affiliation(s)
- Sung-Ho Huh
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jennifer Jones
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Mark E. Warchol
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - David M. Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
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673
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Alternative Splicing of Fibroblast Growth Factor Receptor IgIII Loops in Cancer. J Nucleic Acids 2011; 2012:950508. [PMID: 22203889 PMCID: PMC3238399 DOI: 10.1155/2012/950508] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/27/2011] [Accepted: 08/07/2011] [Indexed: 02/06/2023] Open
Abstract
Alternative splicing
of the IgIII loop of fibroblast growth factor
receptors (FGFRs) 1–3 produces b- and
c-variants of the receptors with distinctly
different biological impact based on their
distinct ligand-binding spectrum. Tissue-specific expression of these splice variants
regulates interactions in embryonic development,
tissue maintenance and repair, and cancer.
Alterations in FGFR2 splicing are involved in
epithelial mesenchymal transition that produces
invasive, metastatic features during tumor
progression.
Recent research has elucidated regulatory factors that determine
the splice choice both on the level of exogenous signaling events
and on the RNA-protein interaction level. Moreover, methodology
has been developed that will enable the in depth analysis of
splicing events during tumorigenesis and provide further insight on
the role of FGFR 1–3 IIIb and IIIc in the pathophysiology of
various malignancies. This paper aims to summarize expression
patterns in various tumor types and outlines possibilities for
further analysis and application.
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674
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Hébert JM. FGFs: Neurodevelopment's Jack-of-all-Trades - How Do They Do it? Front Neurosci 2011; 5:133. [PMID: 22164131 PMCID: PMC3230033 DOI: 10.3389/fnins.2011.00133] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 11/18/2011] [Indexed: 12/02/2022] Open
Abstract
From neurulation to postnatal processes, the requirements for FGF signaling in many aspects of neural precursor cell biology have been well documented. However, identifying a requirement for FGFs in a particular neurogenic process provides only an initial and superficial understanding of what FGF signaling is doing. How FGFs specify cell types in one instance, yet promote cell survival, proliferation, migration, or differentiation in other instances remains largely unknown and is key to understanding how they function. This review describes what we have learned primarily from in vivo vertebrate studies about the roles of FGF signaling in neurulation, anterior–posterior patterning of the neural plate, brain patterning from local signaling centers, and finally neocortex development as an example of continued roles for FGFs within the same brain area. The potential explanations for the diverse functions of FGFs through differential interactions with cell intrinsic and extrinsic factors is then discussed with an emphasis on how little we know about the modulation of FGF signaling in vivo. A clearer picture of the mechanisms involved is nevertheless essential to understand the behavior of neural precursor cells and to potentially guide their fates for therapeutic purposes.
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Affiliation(s)
- Jean M Hébert
- Department of Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA
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675
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Foldynova-Trantirkova S, Wilcox WR, Krejci P. Sixteen years and counting: the current understanding of fibroblast growth factor receptor 3 (FGFR3) signaling in skeletal dysplasias. Hum Mutat 2011; 33:29-41. [PMID: 22045636 DOI: 10.1002/humu.21636] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 09/30/2011] [Indexed: 11/09/2022]
Abstract
In 1994, the field of bone biology was significantly advanced by the discovery that activating mutations in the fibroblast growth factor receptor 3 (FGFR3) receptor tyrosine kinase (TK) account for the common genetic form of dwarfism in humans, achondroplasia (ACH). Other conditions soon followed, with the list of human disorders caused by FGFR3 mutations now reaching at least 10. An array of vastly different diagnoses is caused by similar mutations in FGFR3, including syndromes affecting skeletal development (hypochondroplasia [HCH], ACH, thanatophoric dysplasia [TD]), skin (epidermal nevi, seborrhaeic keratosis, acanthosis nigricans), and cancer (multiple myeloma [MM], prostate and bladder carcinoma, seminoma). Despite many years of research, several aspects of FGFR3 function in disease remain obscure or controversial. As FGFR3-related skeletal dysplasias are caused by growth attenuation of the cartilage, chondrocytes appear to be unique in their response to FGFR3 activation. However, the reasons why FGFR3 inhibits chondrocyte growth while causing excessive cellular proliferation in cancer are not clear. Likewise, the full spectrum of molecular events by which FGFR3 mediates its signaling is just beginning to emerge. This article describes the challenging journey to unravel the mechanisms of FGFR3 function in skeletal dysplasias, the extraordinary cellular manifestations of FGFR3 signaling in chondrocytes, and finally, the progress toward therapy for ACH and cancer.
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676
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Guillemot F, Zimmer C. From cradle to grave: the multiple roles of fibroblast growth factors in neural development. Neuron 2011; 71:574-88. [PMID: 21867876 DOI: 10.1016/j.neuron.2011.08.002] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2011] [Indexed: 01/08/2023]
Abstract
The generation of a functional nervous system involves a multitude of steps that are controlled by just a few families of extracellular signaling molecules. Among these, the fibroblast growth factor (FGF) family is particularly prominent for the remarkable diversity of its functions. FGFs are best known for their roles in the early steps of patterning of the neural primordium and proliferation of neural progenitors. However, other equally important functions have emerged more recently, including in the later steps of neuronal migration, axon navigation, and synaptogenesis. We review here these diverse functions and discuss the mechanisms that account for this unusual range of activities. FGFs are essential components of most protocols devised to generate therapeutically important neuronal populations in vitro or to stimulate neuronal repair in vivo. How FGFs promote the development of the nervous system and maintain its integrity will thus remain an important focus of research in the future.
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Affiliation(s)
- François Guillemot
- Division of Molecular Neurobiology, Medical Research Council, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW71AA, UK.
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677
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Murakami M, Nguyen LT, Hatanaka K, Schachterle W, Chen PY, Zhuang ZW, Black BL, Simons M. FGF-dependent regulation of VEGF receptor 2 expression in mice. J Clin Invest 2011; 121:2668-78. [PMID: 21633168 DOI: 10.1172/jci44762] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 04/13/2011] [Indexed: 01/19/2023] Open
Abstract
Numerous studies have suggested a link between the angiogenic FGF and VEGF signaling pathways; however, the nature of this link has not been established. To evaluate this relationship, we investigated VEGF signaling in ECs with disrupted FGF signaling in vitro and in vivo. ECs lacking FGF signaling became unresponsive to VEGF, caused by downregulation of VEGF receptor 2 (VEGFR2) expression after reduced Vegfr2 enhancer activation. FGF mediated VEGFR2 expression via activation of Erk1/2. Transcriptional analysis revealed that Ets transcription factors controlled VEGFR2 expression in an FGF- and Erk1/2-dependent manner. Mice with defective FGF signaling exhibited loss of vascular integrity and reduced vascular morphogenesis. Thus, basal FGF stimulation of the endothelium is required for maintenance of VEGFR2 expression and the ability to respond to VEGF stimulation and accounts for the hierarchic control of vascular formation by FGFs and VEGF.
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Affiliation(s)
- Masahiro Murakami
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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678
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Faul C, Amaral AP, Oskouei B, Hu MC, Sloan A, Isakova T, Gutiérrez OM, Aguillon-Prada R, Lincoln J, Hare JM, Mundel P, Morales A, Scialla J, Fischer M, Soliman EZ, Chen J, Go AS, Rosas SE, Nessel L, Townsend RR, Feldman HI, St John Sutton M, Ojo A, Gadegbeku C, Di Marco GS, Reuter S, Kentrup D, Tiemann K, Brand M, Hill JA, Moe OW, Kuro-O M, Kusek JW, Keane MG, Wolf M. FGF23 induces left ventricular hypertrophy. J Clin Invest 2011; 121:4393-408. [PMID: 21985788 DOI: 10.1172/jci46122] [Citation(s) in RCA: 1461] [Impact Index Per Article: 112.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 08/25/2011] [Indexed: 12/11/2022] Open
Abstract
Chronic kidney disease (CKD) is a public health epidemic that increases risk of death due to cardiovascular disease. Left ventricular hypertrophy (LVH) is an important mechanism of cardiovascular disease in individuals with CKD. Elevated levels of FGF23 have been linked to greater risks of LVH and mortality in patients with CKD, but whether these risks represent causal effects of FGF23 is unknown. Here, we report that elevated FGF23 levels are independently associated with LVH in a large, racially diverse CKD cohort. FGF23 caused pathological hypertrophy of isolated rat cardiomyocytes via FGF receptor-dependent activation of the calcineurin-NFAT signaling pathway, but this effect was independent of klotho, the coreceptor for FGF23 in the kidney and parathyroid glands. Intramyocardial or intravenous injection of FGF23 in wild-type mice resulted in LVH, and klotho-deficient mice demonstrated elevated FGF23 levels and LVH. In an established animal model of CKD, treatment with an FGF-receptor blocker attenuated LVH, although no change in blood pressure was observed. These results unveil a klotho-independent, causal role for FGF23 in the pathogenesis of LVH and suggest that chronically elevated FGF23 levels contribute directly to high rates of LVH and mortality in individuals with CKD.
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Affiliation(s)
- Christian Faul
- Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA.
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679
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Alternative splicing in oncogenic kinases: from physiological functions to cancer. J Nucleic Acids 2011; 2012:639062. [PMID: 22007291 PMCID: PMC3189609 DOI: 10.1155/2012/639062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/14/2011] [Indexed: 01/13/2023] Open
Abstract
Among the 518 protein kinases encoded by the human kinome, several of them act as oncoproteins in human cancers. Like other eukaryotic genes, oncogenes encoding protein kinases are frequently subjected to alternative splicing in coding as well as noncoding sequences. In the present paper, we will illustrate how alternative splicing can significantly impact on the physiological functions of oncogenic protein kinases, as demonstrated by mouse genetic model studies. This includes examples of membrane-bound tyrosine kinases receptors (FGFR2, Ret, TrkB, ErbB4, and VEGFR) as well as cytosolic protein kinases (B-Raf). We will further discuss how regular alternative splicing events of these kinases are in some instances implicated in oncogenic processes during tumor progression (FGFR, TrkB, ErbB2, Abl, and AuroraA). Finally, we will present typical examples of aberrant splicing responsible for the deregulation of oncogenic kinases activity in cancers (AuroraB, Jak2, Kit, Met, and Ron).
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680
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Fenwick AL, Bowdin SC, Klatt REM, Wilkie AOM. A deletion of FGFR2 creating a chimeric IIIb/IIIc exon in a child with Apert syndrome. BMC MEDICAL GENETICS 2011; 12:122. [PMID: 21943124 PMCID: PMC3192734 DOI: 10.1186/1471-2350-12-122] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 09/23/2011] [Indexed: 12/26/2022]
Abstract
Background Signalling by fibroblast growth factor receptor type 2 (FGFR2) normally involves a tissue-specific alternative splice choice between two exons (IIIb and IIIc), which generates two receptor isoforms (FGFR2b and FGFR2c respectively) with differing repertoires of FGF-binding specificity. Here we describe a unique chimeric IIIb/c exon in a patient with Apert syndrome, generated by a non-allelic homologous recombination event. Case Presentation We present a child with Apert syndrome in whom routine genetic testing had excluded the FGFR2 missense mutations commonly associated with this disorder. The patient was found to harbour a heterozygous 1372 bp deletion between FGFR2 exons IIIb and IIIc, apparently originating from recombination between 13 bp of identical DNA sequence present in both exons. The rearrangement was not present in the unaffected parents. Conclusions Based on the known pathogenesis of Apert syndrome, the chimeric FGFR2 protein is predicted to act in a dominant gain-of-function manner. This is likely to result from its expression in mesenchymal tissues, where retention of most of the residues essential for FGFR2b binding activity would result in autocrine activation. This report adds to the repertoire of rare cases of Apert syndrome for which a pathogenesis based on atypical FGFR2 rearrangements can be demonstrated.
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Affiliation(s)
- Aimee L Fenwick
- Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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681
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Vega-Hernández M, Kovacs A, De Langhe S, Ornitz DM. FGF10/FGFR2b signaling is essential for cardiac fibroblast development and growth of the myocardium. Development 2011; 138:3331-40. [PMID: 21750042 DOI: 10.1242/dev.064410] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The epicardium serves as a source of growth factors that regulate myocardial proliferation and as a source of epicardial-derived cells (EPDC), which give rise to interstitial cardiac fibroblasts and perivascular cells. These progenitors populate the compact myocardium to become part of the mature coronary vasculature and fibrous skeleton of the heart. Little is known about the mechanisms that regulate EPDC migration into the myocardium or the functions carried out by these cells once they enter the myocardium. However, it has been proposed that cardiac fibroblasts are important for growth of the heart during late gestation and are a source of homeostatic factors in the adult. Here, we identify a myocardial to epicardial fibroblast growth factor (FGF) signal, mediated by FGF10 and FGFR2b, that is essential for movement of cardiac fibroblasts into the compact myocardium. Inactivation of this signaling pathway results in fewer epicardial derived cells within the compact myocardium, decreased myocardial proliferation and a resulting smaller thin-walled heart.
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Affiliation(s)
- Mónica Vega-Hernández
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO 63110, USA
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682
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Abstract
Fibroblast growth factors (fgfs) play important roles in embryonic development and in adult life by controlling cell proliferation, differentiation, and migration. There are 18 known fgfs which activate four fibroblast growth factor receptors (FGFRs), with different isoforms due to alternative splicing. The physical basis behind the specificity of the biological responses mediated by different fgf-FGFR pairs is currently unknown. To gain insight into the specificity of FGFR3c, a membrane receptor which is critical for bone development, we studied, analyzed, and compared the activation of FGFR3c over a wide range of fgf1 and fgf2 concentrations. We found that while the strength of fgf2 binding to FGFR3c is lower than the strength of fgf1 binding, the fgf2-bound dimers exhibit higher phosphorylation of the critical tyrosines in the activation loop. As a result, fgf1 and fgf2 elicit a similar FGFR3c response at low, but not at high, concentrations. The results demonstrate the versatility of FGFR3c response to fgf1 and fgf2 and highlight the complexity in fgf signaling.
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Affiliation(s)
- Fenghao Chen
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
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683
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Yu T, Yaguchi Y, Echevarria D, Martinez S, Basson MA. Sprouty genes prevent excessive FGF signalling in multiple cell types throughout development of the cerebellum. Development 2011; 138:2957-68. [PMID: 21693512 DOI: 10.1242/dev.063784] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Fibroblast growth factors (FGFs) and regulators of the FGF signalling pathway are expressed in several cell types within the cerebellum throughout its development. Although much is known about the function of this pathway during the establishment of the cerebellar territory during early embryogenesis, the role of this pathway during later developmental stages is still poorly understood. Here, we investigated the function of sprouty genes (Spry1, Spry2 and Spry4), which encode feedback antagonists of FGF signalling, during cerebellar development in the mouse. Simultaneous deletion of more than one of these genes resulted in a number of defects, including mediolateral expansion of the cerebellar vermis, reduced thickness of the granule cell layer and abnormal foliation. Analysis of cerebellar development revealed that the anterior cerebellar neuroepithelium in the early embryonic cerebellum was expanded and that granule cell proliferation during late embryogenesis and early postnatal development was reduced. We show that the granule cell proliferation deficit correlated with reduced sonic hedgehog (SHH) expression and signalling. A reduction in Fgfr1 dosage during development rescued these defects, confirming that the abnormalities are due to excess FGF signalling. Our data indicate that sprouty acts both cell autonomously in granule cell precursors and non-cell autonomously to regulate granule cell number. Taken together, our data demonstrate that FGF signalling levels have to be tightly controlled throughout cerebellar development in order to maintain the normal development of multiple cell types.
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Affiliation(s)
- Tian Yu
- Department of Craniofacial Development, King's College London, London, UK
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684
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Zhao G, Li WY, Chen D, Henry JR, Li HY, Chen Z, Zia-Ebrahimi M, Bloem L, Zhai Y, Huss K, Peng SB, McCann DJ. A novel, selective inhibitor of fibroblast growth factor receptors that shows a potent broad spectrum of antitumor activity in several tumor xenograft models. Mol Cancer Ther 2011; 10:2200-10. [PMID: 21900693 DOI: 10.1158/1535-7163.mct-11-0306] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The fibroblast growth factor receptors (FGFR) are tyrosine kinases that are present in many types of endothelial and tumor cells and play an important role in tumor cell growth, survival, and migration as well as in maintaining tumor angiogenesis. Overexpression of FGFRs or aberrant regulation of their activities has been implicated in many forms of human malignancies. Therefore, targeting FGFRs represents an attractive strategy for development of cancer treatment options by simultaneously inhibiting tumor cell growth, survival, and migration as well as tumor angiogenesis. Here, we describe a potent, selective, small-molecule FGFR inhibitor, (R)-(E)-2-(4-(2-(5-(1-(3,5-Dichloropyridin-4-yl)ethoxy)-1H-indazol-3yl)vinyl)-1H-pyrazol-1-yl)ethanol, designated as LY2874455. This molecule is active against all 4 FGFRs, with a similar potency in biochemical assays. It exhibits a potent activity against FGF/FGFR-mediated signaling in several cancer cell lines and shows an excellent broad spectrum of antitumor activity in several tumor xenograft models representing the major FGF/FGFR relevant tumor histologies including lung, gastric, and bladder cancers and multiple myeloma, and with a well-defined pharmacokinetic/pharmacodynamic relationship. LY2874455 also exhibits a 6- to 9-fold in vitro and in vivo selectivity on inhibition of FGF- over VEGF-mediated target signaling in mice. Furthermore, LY2874455 did not show VEGF receptor 2-mediated toxicities such as hypertension at efficacious doses. Currently, this molecule is being evaluated for its potential use in the clinic.
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Affiliation(s)
- Genshi Zhao
- Cancer Research, DC0434, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
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685
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Ratzka A, Baron O, Grothe C. FGF-2 deficiency does not influence FGF ligand and receptor expression during development of the nigrostriatal system. PLoS One 2011; 6:e23564. [PMID: 21876757 PMCID: PMC3158085 DOI: 10.1371/journal.pone.0023564] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 07/21/2011] [Indexed: 11/21/2022] Open
Abstract
Secreted proteins of the fibroblast growth factor (FGF) family play important roles during development of various organ systems. A detailed knowledge of their temporal and spatial expression profiles, especially of closely related FGF family members, are essential to further identification of specific functions in distinct tissues. In the central nervous system dopaminergic neurons of the substantia nigra and their axonal projections into the striatum progressively degenerate in Parkinson's disease. In contrast, FGF-2 deficient mice display increased numbers of dopaminergic neurons. In this study, we determined the expression profiles of all 22 FGF-ligands and 10 FGF-receptor isoforms, in order to clarify, if FGF-2 deficiency leads to compensatory up-regulation of other FGFs in the nigrostriatal system. Three tissues, ventral mesencephalon (VM), striatum (STR) and as reference tissue spinal cord (SC) of wild-type and FGF-2 deficient mice at four developmental stages E14.5, P0, P28, and adult were comparatively analyzed by quantitative RT-PCR. As no differences between the genotypes were observed, a compensatory up-regulation can be excluded. Moreover, this analysis revealed that the majority of FGF-ligands (18/22) and FGF-receptors (9/10) are expressed during normal development of the nigrostriatal system and identified dynamic changes for some family members. By comparing relative expression level changes to SC reference tissue, general alterations in all 3 tissues, such as increased expression of FGF-1, -2, -22, FgfR-2c, -3c and decreased expression of FGF-13 during postnatal development were identified. Further, specific changes affecting only one tissue, such as increased FGF-16 (STR) or decreased FGF-17 (VM) expression, or two tissues, such as decreased expression of FGF-8 (VM, STR) and FGF-15 (SC, VM) were found. Moreover, 3 developmentally down-regulated FGFs (FGF-8b, FGF-15, FGF-17a) were functionally characterized by plasmid-based over-expression in dissociated E11.5 VM cell cultures, however, such a continuous exposure had no influence on the yield of dopaminergic neurons in vitro.
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Affiliation(s)
- Andreas Ratzka
- Institute of Neuroanatomy, Hannover Medical School, Hannover, Germany
| | - Olga Baron
- Institute of Neuroanatomy, Hannover Medical School, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Claudia Grothe
- Institute of Neuroanatomy, Hannover Medical School, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
- * E-mail:
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686
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Yan D, Chen D, Cool SM, van Wijnen AJ, Mikecz K, Murphy G, Im HJ. Fibroblast growth factor receptor 1 is principally responsible for fibroblast growth factor 2-induced catabolic activities in human articular chondrocytes. Arthritis Res Ther 2011; 13:R130. [PMID: 21835001 PMCID: PMC3239372 DOI: 10.1186/ar3441] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 06/06/2011] [Accepted: 08/11/2011] [Indexed: 02/01/2023] Open
Abstract
INTRODUCTION Cartilage degeneration driven by catabolic stimuli is a critical pathophysiological process in osteoarthritis (OA). We have defined fibroblast growth factor 2 (FGF-2) as a degenerative mediator in adult human articular chondrocytes. Biological effects mediated by FGF-2 include inhibition of proteoglycan production, up-regulation of matrix metalloproteinase-13 (MMP-13), and stimulation of other catabolic factors. In this study, we identified the specific receptor responsible for the catabolic functions of FGF-2, and established a pathophysiological connection between the FGF-2 receptor and OA. METHODS Primary human articular chondrocytes were cultured in monolayer (24 hours) or alginate beads (21 days), and stimulated with FGF-2 or FGF18, in the presence or absence of FGFR1 (FGF receptor 1) inhibitor. Proteoglycan accumulation and chondrocyte proliferation were assessed by dimethylmethylene blue (DMMB) assay and DNA assay, respectively. Expression of FGFRs (FGFR1 to FGFR4) was assessed by flow cytometry, immunoblotting, and quantitative real-time PCR (qPCR). The distinctive roles of FGFR1 and FGFR3 after stimulation with FGF-2 were evaluated using either pharmacological inhibitors or FGFR small interfering RNA (siRNA). Luciferase reporter gene assays were used to quantify the effects of FGF-2 and FGFR1 inhibitor on MMP-13 promoter activity. RESULTS Chondrocyte proliferation was significantly enhanced in the presence of FGF-2 stimulation, which was inhibited by the pharmacological inhibitor of FGFR1. Proteoglycan accumulation was reduced by 50% in the presence of FGF-2, and this reduction was successfully rescued by FGFR1 inhibitor. FGFR1 inhibitors also fully reversed the up-regulation of MMP-13 expression and promoter activity stimulated by FGF-2. Blockade of FGFR1 signaling by either chemical inhibitors or siRNA targeting FGFR1 rather than FGFR3 abrogated the up-regulation of matrix metalloproteinases 13 (MMP-13) and a disintegrin and metalloproteinase with a thrombospondin type 1 motif 5 (ADAMTS5), as well as down-regulation of aggrecan after FGF-2 stimulation. Flow cytometry, qPCR and immunoblotting analyses suggested that FGFR1 and FGFR3 were the major FGFR isoforms expressed in human articular chondrocytes. FGFR1 was activated more potently than FGFR3 upon FGF-2 stimulation. In osteoarthritic chondrocytes, FGFR3 was significantly down regulated (P < 0.05) with a concomitant increase in the FGFR1 to FGFR3 expression ratio (P < 0.05), compared to normal chondrocytes. Our results also demonstrate that FGFR3 was negatively regulated by FGF-2 at the transcriptional level through the FGFR1-ERK (extracellular signal-regulated kinase) signaling pathway in human articular chondrocytes. CONCLUSIONS FGFR1 is the major mediator with the degenerative potential in the presence of FGF-2 in human adult articular chondrocytes. FGFR1 activation by FGF-2 promotes catabolism and impedes anabolism. Disruption of the balance between FGFR1 and FGFR3 signaling ratio may contribute to the pathophysiology of OA.
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Affiliation(s)
- Dongyao Yan
- Department of Biochemistry, Rush University Medical Center, 1735 W Harrison Street, Chicago, IL 60612, USA
| | - Di Chen
- Department of Biochemistry, Rush University Medical Center, 1735 W Harrison Street, Chicago, IL 60612, USA
| | - Simon M Cool
- Department of Stem Cells and Tissue Repair, Institute of Medical Biology, A*STAR, 8A Biomedical Grove, #06-06 Immunos, 138648 Singapore
- Division of Musculoskeletal Oncology, Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, 119074 Singapore
| | - Andre J van Wijnen
- Division of Musculoskeletal Oncology, Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, 119074 Singapore
- Department of Cell Biology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Katalin Mikecz
- Orthopedic Surgery, Rush University Medical Center, 1735 W Harrison Street, Chicago, IL 60612, USA
| | - Gillian Murphy
- Department of Oncology, Cambridge University, Cancer Research Institute, Li Ka Shing Center, Robinson Way, Cambridge, CB2 ORE, UK
| | - Hee-Jeong Im
- Department of Biochemistry, Rush University Medical Center, 1735 W Harrison Street, Chicago, IL 60612, USA
- Department of Internal Medicine, Section of Rheumatology, Rush University Medical Center, 1735 W Harrison Street, Chicago, IL 60612, USA
- Orthopedic Surgery, Rush University Medical Center, 1735 W Harrison Street, Chicago, IL 60612, USA
- Department of Bioengineering, University of Illinois, 1304 West Springfield Avenue, Chicago, IL 60612, USA
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687
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Gattineni J, Twombley K, Goetz R, Mohammadi M, Baum M. Regulation of serum 1,25(OH)2 vitamin D3 levels by fibroblast growth factor 23 is mediated by FGF receptors 3 and 4. Am J Physiol Renal Physiol 2011; 301:F371-7. [PMID: 21561999 PMCID: PMC3154596 DOI: 10.1152/ajprenal.00740.2010] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 05/08/2011] [Indexed: 12/29/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone implicated in the pathogenesis of several hypophosphatemic disorders. FGF23 causes hypophosphatemia by decreasing the expression of sodium phosphate cotransporters (NaPi-2a and NaPi-2c) and decreasing serum 1,25(OH)(2)Vitamin D(3) levels. We previously showed that FGFR1 is the predominant receptor for the hypophosphatemic actions of FGF23 by decreasing renal NaPi-2a and 2c expression while the receptors regulating 1,25(OH)(2)Vitamin D(3) levels remained elusive. To determine the FGFRs regulating 1,25(OH)(2)Vitamin D(3) levels, we studied FGFR3(-/-)FGFR4(-/-) mice as these mice have shortened life span and are growth retarded similar to FGF23(-/-) and Klotho(-/-) mice. Baseline serum 1,25(OH)(2)Vitamin D(3) levels were elevated in the FGFR3(-/-)FGFR4(-/-) mice compared with wild-type mice (102.2 ± 14.8 vs. 266.0 ± 34.0 pmol/l; P = 0.001) as were the serum levels of FGF23. Administration of recombinant FGF23 had no effect on serum 1,25(OH)(2)Vitamin D(3) in the FGFR3(-/-)FGFR4(-/-) mice (173.4 ± 32.7 vs. 219.7 ± 56.5 pmol/l; vehicle vs. FGF23) while it reduced serum 1,25(OH)(2)Vitamin D(3) levels in wild-type mice. Administration of FGF23 to FGFR3(-/-)FGFR4(-/-) mice resulted in a decrease in serum parathyroid hormone (PTH) levels and an increase in serum phosphorus levels mediated by increased renal phosphate reabsorption. These data indicate that FGFR3 and 4 are the receptors that regulate serum 1,25(OH)(2)Vitamin D(3) levels in response to FGF23. In addition, when 1,25(OH)(2)Vitamin D(3) levels are not affected by FGF23, as in FGFR3(-/-)FGFR4(-/-) mice, a reduction in PTH can override the effects of FGF23 on renal phosphate transport.
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Affiliation(s)
- Jyothsna Gattineni
- Dept. of Pediatrics, U.T. Southwestern Medical Center, Dallas, TX 75390-9063, USA.
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688
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Fukui L, Henry JJ. FGF signaling is required for lens regeneration in Xenopus laevis. THE BIOLOGICAL BULLETIN 2011; 221:137-45. [PMID: 21876116 PMCID: PMC3442785 DOI: 10.1086/bblv221n1p137] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In species of the frog genus Xenopus, lens regeneration occurs through a process of transdifferentiation, in which cornea epithelial cells presumably undergo dedifferentiation and subsequently redifferentiate to form a new lens. Experimental studies have shown that the retina provides the key signal required to trigger this process once the original lens is removed. A previous study showed that addition of an exogenous fibroblast growth factor (i.e., FGF1 protein) could initiate transdifferentiation of cornea epithelial cells in culture. To determine the role of FGF signaling in X. laevis lens regeneration, we have examined the presence of specific FGFs and their receptors (FGFRs) during this process and evaluated the necessity of FGFR signaling. Reverse transcriptase-polymerase chain reaction analyses reveal that a number of FGF family members are expressed in cornea epithelium and retinal tissues both before and during the process of lens regeneration. Of these, FGF1, FGF8, and FGF9 are expressed principally in retinal tissue and not in the cornea epithelium. Hence, these ligands could represent key signaling factors originating from the retina that trigger regeneration. The results of experiments using an in vitro eye culture system and an FGFR inhibitor (SU5402) suggest that FGFR signaling is required for lens regeneration in Xenopus.
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Affiliation(s)
- Lisa Fukui
- University of Illinois, Department of Cell and Developmental Biology, Urbana, Illinois 61801, USA
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689
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Liu P, Chen L, Bai X, Karaplis A, Miao D, Gu N. Impairment of spatial learning and memory in transgenic mice overexpressing human fibroblast growth factor-23. Brain Res 2011; 1412:9-17. [PMID: 21824606 DOI: 10.1016/j.brainres.2011.07.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2011] [Revised: 07/01/2011] [Accepted: 07/12/2011] [Indexed: 12/17/2022]
Abstract
Fibroblast growth factor-23 (FGF-23) is a potent circulating phosphaturic factor associated with renal phosphate wasting. Effects of FGF-23 on skeleton, phosphate homeostasis, and cardiovascular system have been investigated; however, the effect of FGF-23 on the central nervous system (CNS) is unknown. To assess whether FGF-23 influences the function and structure of the CNS and whether the effect of FGF-23 on the CNS is mediated by FGF receptors directly or by hypophosphatemia indirectly, FGF-23 transgenic mice and their wild-type littermates were fed a normal diet or a high-phosphate diet containing a normal diet plus 1.25% phosphate in drinking water from weaning for 5weeks and the phenotypes of the CNS were compared between FGF-23 transgenic mice and their wild-type littermates on the same diet. At the end of this time period, transgenic animals on the normal diet showed impaired spatial learning and memory. Furthermore, these mice exhibited the impairment of long-term potentiation in hippocampal CA1 region, and the reduction of hippocampal adenosine-triphosphate content and of choline acetyltransferase-positive neurons in basal forebrain, possibly as pathogenetic factors contributing to the cognitive deficit. The central nervous phenotypes of transgenic mice were rescued following improved hypophosphatemia by the high-phosphate diet intake. This study demonstrates that FGF-23 overexpression can result in abnormalities in the CNS mediated by the secondary severe hypophosphatemia.
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Affiliation(s)
- Peidang Liu
- Department of Toxicology, School of Public Health, Southeast University, Nanjing 210009, PR China
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690
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Fibroblast growth factor receptors as therapeutic targets in human melanoma: synergism with BRAF inhibition. J Invest Dermatol 2011; 131:2087-95. [PMID: 21753785 DOI: 10.1038/jid.2011.177] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cutaneous melanoma is a tumor with rising incidence and a very poor prognosis at the disseminated stage. Melanomas are characterized by frequent mutations in BRAF and also by overexpression of fibroblast growth factor 2 (FGF2), offering opportunities for therapeutic intervention. We investigated inhibition of FGF signaling and its combination with dacarbazine or BRAF inhibitors as an antitumor strategy in melanoma. The majority of melanoma cell lines displayed overexpression of FGF2 but also FGF5 and FGF18 together with different isoforms of FGF receptors (FGFRs) 1-4. Blockade of FGF signals with dominant-negative receptor constructs (dnFGFR1, 3, or 4) or small-molecule inhibitors (SU5402 and PD166866) reduced melanoma cell proliferation, colony formation, as well as anchorage-independent growth, and increased apoptosis. DnFGFR constructs also significantly inhibited tumor growth in vivo. Combination of FGF inhibitors with dacarbazine showed additive or antagonistic effects, whereas synergistic drug interaction was observed when combining FGFR inhibition with the multikinase/BRAF inhibitor sorafenib or the V600E mutant-specific BRAF inhibitor RG7204. In conclusion, FGFR inhibition has antitumor effects against melanoma cells in vitro and in vivo. Combination with BRAF inhibition offers a potential for synergistic antimelanoma effects and represents a promising therapeutic strategy against advanced melanoma.
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691
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Wu X, Yan Q, Huang Y, Huang H, Su Z, Xiao J, Zeng Y, Wang Y, Nie C, Yang Y, Li X. Isolation of a novel basic FGF-binding peptide with potent antiangiogenetic activity. J Cell Mol Med 2011; 14:351-6. [PMID: 20414975 PMCID: PMC3837584 DOI: 10.1111/j.1582-4934.2008.00506.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Basic fibroblast growth factor (bFGF), which plays an important role in tumour angiogenesis and progression, provides a potential target for cancer therapy. Here we screened a phage display heptapeptide library with bFGF and identified 11 specific bFGF-binding phage clones. Two of these clones had identical sequence and the corresponding peptide (referred to as P7) showed high homology to the immunoglobulin-like (Ig-like) domain III (D3) of high-affinity bFGF receptors, FGFR1 (IIIc) and FGFR2 (IIIc). The P7 peptide and its corresponding motif in D3 of FGFRs both carried negative charges and shared similar hydrophobic profiles. Functional analysis demonstrated that synthetic P7 peptides mediate strong inhibition of bFGF-induced cell proliferation and neovascularization. Our results demonstrate that the P7 peptide is a potent bFGF antagonist with strong antiangiogenetic activity, and might have therapeutic potential in cancer therapy.
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Affiliation(s)
- Xiaoping Wu
- School of Pharmaceutical Science, Key Laboratory of Biotechnology and Pharmaceutical Engineering of Zhejiang Province, Wenzhou Medical College, Wenzhou, China
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692
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Nakajima T, Hayashi S, Iguchi T, Sato T. The role of fibroblast growth factors on the differentiation of vaginal epithelium of neonatal mice. Differentiation 2011; 82:28-37. [DOI: 10.1016/j.diff.2011.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 02/23/2011] [Accepted: 03/28/2011] [Indexed: 11/26/2022]
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693
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Kralisch S, Fasshauer M. Fibroblast growth factor 21: effects on carbohydrate and lipid metabolism in health and disease. Curr Opin Clin Nutr Metab Care 2011; 14:354-9. [PMID: 21505329 DOI: 10.1097/mco.0b013e328346a326] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The review summarizes recent findings examining the effects of fibroblast growth factor (FGF) 21 on carbohydrate and lipid metabolism with emphasis on publications from 2010. RECENT FINDINGS FGF21 is considered to be a metabolic hormone rather than a traditional growth factor. Recent studies identified the important role of FGF21 in regulation of energy balance. Thus, the protein regulates hepatic metabolism and improves insulin sensitivity. Furthermore, central FGF21 action in the brain increases energy expenditure and insulin sensitivity in rodents. Interestingly, FGF21 expression is elevated in the adaptive response to fasting but also regulated by feeding-induced mechanisms. Moreover, FGF21 levels are elevated in obese animals and positively correlate with BMI in humans suggesting obesity as a FGF21-resistant state. SUMMARY FGF21 is a metabolic hormone that is regulated by nutritional status and influences glucose and lipid metabolism by central and peripheral mechanisms. Future research is needed to expand our understanding of the diagnostic and therapeutic relevance of FGF21-dependent pathways in humans.
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Affiliation(s)
- Susan Kralisch
- IFB AdiposityDiseases, Leipzig University Medical Center, Medical Department, University of Leipzig, Leipzig, Germany
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694
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Dabrowski A, Umemori H. Orchestrating the synaptic network by tyrosine phosphorylation signalling. J Biochem 2011; 149:641-53. [PMID: 21508038 PMCID: PMC3143439 DOI: 10.1093/jb/mvr047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 04/08/2011] [Indexed: 01/07/2023] Open
Abstract
The establishment of a functional brain requires coordinated and stereotyped formation of synapses between neurons. For this, trans-synaptic molecular cues (synaptic organizers) are exchanged between a neuron and its target to organize appropriate synapses. The understanding of signalling mechanisms by which such synaptic organizers lead to synapse formation is just being elucidated. However, recent studies revealed that some of these cues act through receptor protein tyrosine kinases (RPTKs) or phosphatases (RPTPs). Synaptogenic RPTKs and RPTPs pattern synaptic network through affecting local protein-protein binding dynamics, changing the phosphorylation state of signalling cascades, or promoting gene expression. Each RPTK or RPTP has distinct roles in synapse formation, serving at different synapses or showing differential synaptogenic effects. Thus, tyrosine phosphorylation signalling plays critical roles in building the orchestrated synaptic circuitry in the brain.
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Affiliation(s)
- Ania Dabrowski
- Molecular & Behavioral Neuroscience Institute, Medical Scientist Training Program, Neuroscience Graduate Program and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Hisashi Umemori
- Molecular & Behavioral Neuroscience Institute, Medical Scientist Training Program, Neuroscience Graduate Program and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
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695
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Chen Q, Jiang Y, An Y, Zhao N, Zhao Y, Yu C. Soluble FGFR4 extracellular domain inhibits FGF19-induced activation of FGFR4 signaling and prevents nonalcoholic fatty liver disease. Biochem Biophys Res Commun 2011; 409:651-6. [PMID: 21616061 DOI: 10.1016/j.bbrc.2011.05.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 05/11/2011] [Indexed: 12/30/2022]
Abstract
Fibroblast growth factor receptor 4 (FGFR4) is a transmembrane tyrosine kinase receptor that plays a crucial role in the regulation of hepatic bile acid and lipid metabolism. FGFR4 underlies high-fat diet-induced hepatic steatosis, suggesting that inhibition of FGFR4 activation may be an effective way to prevent or treat nonalcoholic fatty liver disease (NAFLD). To determine whether neutralization of FGFR4 ligands by soluble FGFR4 extracellular domain (FGFR4-ECD) can inhibit the activation of FGFR4, we constructed FGFR4-ECD expression vector and showed that FGFR4-ECD was effectively expressed in cells and secreted into culture medium. FGFR4-ECD inhibited FGF19-induced activation of FGFR4 signaling and reduced steatosis of HepG2 induced by palmitic acid in vitro. Furthermore, in a tetracycline-induced fatty liver model, expression of FGFR4-ECD in mouse liver reduced the accumulation of hepatic lipids and partially restored the expression of peroxisome proliferator-activated receptor α (PPARα), which promotes the mitochondrial fatty acid beta-oxidation but is repressed by tetracycline. Taken together, these results demonstrate that FGFR4-ECD can block FGFR4 signaling and prevent hepatic steatosis, highlighting the potential value of inhibition of FGFR4 signaling as a method for therapeutic intervention against NAFLD.
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Affiliation(s)
- Qiang Chen
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, China
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696
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Martínez-Frías ML, Egüés X, Puras A, Hualde J, de Frutos CA, Bermejo E, Nieto MA, Martínez S. Thanatophoric dysplasia type II with encephalocele and semilobar holoprosencephaly: Insights into its pathogenesis. Am J Med Genet A 2011; 155A:197-202. [PMID: 21204232 DOI: 10.1002/ajmg.a.33765] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Thanatophoric dysplasia (TD) is a lethal form of short-limb skeletal dysplasia that is associated with macrocephaly, and variably cloverleaf skull. Two types of TD are clinically recognized, TD1 and TD2, mainly distinguished by their radiographic characteristics. The differences between the two are principally observed in the femur, which appears curved in TD1, while it remains straight but with a proximal medial spike in TD2, and are a less severe overall affectation in TD2. Both types of TD are caused by mutations in different functional domains of the FGFR3 gene. However, whereas several mutations in the different domains of FGFR3 cause TD1, the K650E mutation involving the change of a lysine to glutamic acid ("Lys650Glu") has been found in all TD2 cases to date. Here we describe a newborn infant with TD2 associated with brain defects that have either been infrequently observed (encephalocele) or not hitherto described (holoprosencephaly). Based on recent studies, we consider encephaloceles described in TD to be pseudoencephaloceles, since they are secondary to the intracranial pressure generated by severe hydrocephaly and to severe cranial structural anomalies. Finally, to analyze the mechanisms of holoprosencephaly observed in the case described here, we include a concise review on the current understanding of how FGFs and their receptors are expressed in the rostral signaling center (particularly Fgf8). In addition, we evaluated recent observations that FGF ligands and receptors (including FGFR3) act in concert to organize the whole telencephalon activity, rather than independently patterning different areas.
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Affiliation(s)
- M L Martínez-Frías
- ECEMC, Centro de Investigación de Anomalías Congénitas, Instituto de Salud Carlos III, Madrid, Spain.
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697
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Sims-Lucas S, Cusack B, Baust J, Eswarakumar VP, Masatoshi H, Takeuchi A, Bates CM. Fgfr1 and the IIIc isoform of Fgfr2 play critical roles in the metanephric mesenchyme mediating early inductive events in kidney development. Dev Dyn 2011; 240:240-9. [PMID: 21128305 DOI: 10.1002/dvdy.22501] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Fibroblast growth factor receptors (Fgfrs) have critical roles in kidney development. FgfrIIIb is thought to act in epithelium, while FgfrIIIc functions in mesenchyme. We aimed to determine roles of Fgfr2IIIc in kidney development. Mice with deletion of Fgfr2IIIc (Fgfr2IIIc-/-) had normal kidneys. Combination of Fgfr2IIIc-/- with conditional deletion of Fgfr1 in metanephric mesenchyme (MM) (Fgfr1(Mes-/-)Fgfr2IIIc-/-) had small but identifiable MM at embryonic day (E) 10.5, expressing mesenchymal markers including Eya1, Six2, Pax2, and Gdnf (unlike Fgfr1/2(Mes-/-) mice that have no obvious MM). E11.5 Fgfr1(Mes-/-)Fgfr2IIIc-/- mice had rudimentary MM expressing only Eya1. Control, Fgfr2IIIc-/-, and Fgfr1(Mes-/-)Fgfr2IIIc-/- kidney mesenchymal tissues also express Fgfr2IIIb. In ureteric lineages, E10.5 Fgfr1(Mes-/-)Fgfr2IIIc-/- embryos had ureteric outgrowth (sometimes multiple buds); however, by E11.5 Gdnf absence lead to no ureteric elongation or branching (similar to Fgfr1/2(Mes-/-) mice). Beyond E12.5, Fgfr1(Mes-/-)Fgfr2IIIc-/- mice had no renal tissue. In conclusion, Fgfr2IIIc and Fgfr1 in kidney mesenchyme (together) are critical for normal early renal development.
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Affiliation(s)
- Sunder Sims-Lucas
- Rangos Research Center, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA
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698
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Peterslund JM, Serup P. Activation of FGFR(IIIc) isoforms promotes activin-induced mesendoderm development in mouse embryonic stem cells and reduces Sox17 coexpression in EpCAM+ cells. Stem Cell Res 2011; 6:262-75. [DOI: 10.1016/j.scr.2011.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 02/17/2011] [Accepted: 02/18/2011] [Indexed: 01/04/2023] Open
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699
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Identification and characterization of an inhibitory fibroblast growth factor receptor 2 (FGFR2) molecule, up-regulated in an Apert Syndrome mouse model. Biochem J 2011; 436:71-81. [DOI: 10.1042/bj20100884] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AS (Apert syndrome) is a congenital disease composed of skeletal, visceral and neural abnormalities, caused by dominant-acting mutations in FGFR2 [FGF (fibroblast growth factor) receptor 2]. Multiple FGFR2 splice variants are generated through alternative splicing, including PTC (premature termination codon)-containing transcripts that are normally eliminated via the NMD (nonsense-mediated decay) pathway. We have discovered that a soluble truncated FGFR2 molecule encoded by a PTC-containing transcript is up-regulated and persists in tissues of an AS mouse model. We have termed this IIIa–TM as it arises from aberrant splicing of FGFR2 exon 7 (IIIa) into exon 10 [TM (transmembrane domain)]. IIIa–TM is glycosylated and can modulate the binding of FGF1 to FGFR2 molecules in BIAcore-binding assays. We also show that IIIa–TM can negatively regulate FGF signalling in vitro and in vivo. AS phenotypes are thought to result from gain-of-FGFR2 signalling, but our findings suggest that IIIa–TM can contribute to these through a loss-of-FGFR2 function mechanism. Moreover, our findings raise the interesting possibility that FGFR2 signalling may be a regulator of the NMD pathway.
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700
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Frontini MJ, Nong Z, Gros R, Drangova M, O'Neil C, Rahman MN, Akawi O, Yin H, Ellis CG, Pickering JG. Fibroblast growth factor 9 delivery during angiogenesis produces durable, vasoresponsive microvessels wrapped by smooth muscle cells. Nat Biotechnol 2011; 29:421-7. [PMID: 21499246 DOI: 10.1038/nbt.1845] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 03/14/2011] [Indexed: 12/13/2022]
Abstract
The therapeutic potential of angiogenic growth factors has not been realized. This may be because formation of endothelial sprouts is not followed by their muscularization into vasoreactive arteries. Using microarray expression analysis, we discovered that fibroblast growth factor 9 (FGF9) was highly upregulated as human vascular smooth muscle cells (SMCs) assemble into layered cords. FGF9 was not angiogenic when mixed with tissue implants or delivered to the ischemic mouse hind limb, but instead orchestrated wrapping of SMCs around neovessels. SMC wrapping in implants was driven by sonic hedgehog-mediated upregulation of PDGFRβ. Computed tomography microangiography and intravital microscopy revealed that microvessels formed in the presence of FGF9 had enhanced capacity to receive flow and were vasoreactive. Moreover, the vessels persisted beyond 1 year, remodeling into multilayered arteries paired with peripheral nerves. This mature physiological competency was attained by targeting mesenchymal cells rather than endothelial cells, a finding that could inform strategies for therapeutic angiogenesis and tissue engineering.
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Affiliation(s)
- Matthew J Frontini
- Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada
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