Original Article
Cloning and Expression of Fibroblast Growth Factor Receptor-1 Isoforms in the Mouse Heart: Evidence for Isoform Switching During Heart Development

https://doi.org/10.1006/jmcc.1994.1164Get rights and content

Abstract

Basic (b) fibroblast growth factor (FGF) mediates various biological responses including mitogenesis and angiogenesis by binding to specific cell surface receptors of the tyrosine kinase family. The bFGF receptor-1 (FGFR1) exists in short and long isoforms due to alternate RNA splicing. Minor alterations in the amino acid sequence have also led to reports of different FGFR1 isoforms in different tissues even in the same species. In the absence of any sequence for heart FGFR1 and accumulating evidence for a role of bFGF in heart growth and differentiation, we cloned FGFR1 from embryonic mouse hearts. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to generate full-length short (2259 base pairs) and long (2526 base pairs) forms of FGFR1 cDNAs which generated 86 and 102 kDa proteins, respectively, following in vitro translation. Embryonic mouse heart FGFR1 differed by seven amino acids from the reported sequence for mouse neuroepithelial FGFR1 and appeared more similar to human placental FGFR1. A single FGFR1 transcript of ∼4.3 kb was seen in RNA isolated from embryonic as well as adult mouse hearts. There was a decrease (∼8.5-fold) in FGFR1 RNA levels in the adult. The majority of FGFR1 transcripts in the adult as well as embryonic heart contained exon IIIc (FGFR1-IIIc) which is associated with isoforms that display the highest affinity for bFGF. However, the relative ration of short versus long FGFR1 RNA expression was 0.5 in the embryonic heart compared to 5.9 in the adult heart. These results indicate that: (i) structurally distinct short and long FGFR1 isoform RNAs are expressed in the embryonic and adult heart; (ii) FGFR1-IIIc is the major form of receptor expressed in the embryonic as well as adult heart; (iii) the transition from the embryo to the adult stage is associated with a decrease but not absence of FGFR1 RNA expression; and (iv) long FGFR1-isoforms are more abundant in the embryo while short FGFR1 isoforms predominate in the adult.

References (0)

Cited by (47)

  • The FGF21 Receptor Signaling Complex: Klothoβ, FGFR1c, and Other Regulatory Interactions

    2016, Vitamins and Hormones
    Citation Excerpt :

    Conversely, malignant astrocytomas have been shown to express both FGFR1α and FGFR1β isoforms, while normal fetal and adult brain express only FGFR1α (Yamaguchi, Saya, Bruner, & Morrison, 1994). Similarly, while the “long” (α) isoform of FGFR1 was expressed in embryonic mouse heart, only the “short” (β) FGFR1 isoform was detected in adult heart (Jin et al., 1994). Similarly, FGFR2α and FGFR2β isoforms have also been shown to be differentially expressed during amphibian development (Shi, Launay, Fromentoux, Feige, & Boucaut, 1994).

  • Leupeptin enhances cell surface localization of fibroblast growth factor receptor 1 in adult sensory neurons by increased recycling

    2012, European Journal of Cell Biology
    Citation Excerpt :

    Collectively, our data indicate that enhanced recycling of FGFR1 strongly promotes axonal elongation, but not axonal branching, of adult DRG neurons in vitro. We used FGFR1 IIIc (three Ig-like domains in the extracellular domain) coupled to EGFP (FGFR1-EGFP; Jin et al., 1994) for transfection of PC12 pheochromocytoma cells and dissociated DRG neuron cultures. Stable PC12 cell FGFR1-EGFP transfectants were generated as described before (Hausott et al., 2008; clone L1 was used for this study) and cultured in collagen-coated optical plastic dishes (Ibidi, Austria) under standard conditions in a humidified atmosphere at 37 °C with 5% CO2.

  • Inhibition of fibroblast growth factor receptor 1 endocytosis promotes axonal branching of adult sensory neurons

    2011, Neuroscience
    Citation Excerpt :

    FGFR1 IIIc (three Ig-like domains in the extracellular domain) coupled to EGFP (FGFR1-EGFP; Jin et al., 1994) was used for transfection of PC12 cells and DRG neurons.

  • Endothelium-targeted overexpression of constitutively active FGF receptor induces cardioprotection in mice myocardial infarction

    2009, Journal of Molecular and Cellular Cardiology
    Citation Excerpt :

    The biological effects of extracellular FGF2 are mediated by binding to high-affinity FGFR1–4 of the tyrosine kinase family [11]. FGFR-1 is the best studied FGFR in embryonic, neonatal, and adult cardiomyocytes [12,13]. Activated FGFRs recruit and phosphorylate other signaling molecules, culminating in the activation of major signal transduction pathways such as all three branches of the mitogen activated protein kinase (MAPK pathway), the phospholipase C/protein kinase C (PKC)-, and PI3-kinase/Akt- and Src-associated pathways [14], leading to cell proliferation and differentiation, whereas FGFR also transmits negative cell proliferative effects by inhibition of the Ras/MAPK pathway or induction of cell cycle inhibitors [15].

  • Promotion of neurite outgrowth by fibroblast growth factor receptor 1 overexpression and lysosomal inhibition of receptor degradation in pheochromocytoma cells and adult sensory neurons

    2008, Neuroscience
    Citation Excerpt :

    RPMI 1640 cell culture medium (Gibco Invitrogen, Lofer, Austria) supplemented with 10% horse serum (Gibco Invitrogen), 5% fetal bovine serum (Gibco Invitrogen) and antibiotic-antimycotic (100 units/ml penicillin, 100 μg/ml streptomycin, 0.25 μg/ml amphotericin, Gibco Invitrogen) was changed two times a week. FGFR1S (FGFR1β, two Ig-like domains, IgIIIc) and FGFR1L (FGFR1α, three Ig-like domains, IgIIIc) fused to EGFP (gifts from Dr. P. Cattini; the study was supported by the Medical University Innsbruck, Christoph-Probst-Platz Innrain 52, A-6020 Innsbruck; Jin et al., 1994) were applied for transfection. PC12 cells were transfected using the Amaxa Nucleofector™ (program U-29).

View all citing articles on Scopus
View full text