PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Fibroblast Growth Factor 2”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1992

Promoter region of the murine fibroblast growth factor receptor 2 (bek/KGFR) gene.

Fibroblast growth factors (FGFs) and their receptors play an important role in cell growth, angiogenesis and embryonal development. Four distinct genes encoding fibroblast growth factor receptors (FGFRs) were identified: flg, encoding FGFR1, bek encoding FGFR2, and the genes for FGFR3 and FGFR4. Both FGFR2 and keratinocyte growth factor receptor (KGFR) are encoded by the same gene, bek. To study the regulation of expression of the FGF receptors we analysed the DNA sequence flanking the 5' region of the cDNA of murine FGFR2 to seek elements that control its transcription. A 5-kbp fragment containing the 5' end of the cDNA was isolated from mouse genomic library and used to map the promoter region. We found that the sequence encoding the 5' non-translated region of the FGFR2/KGFR cDNA contains an intron located 210 bp upstream from the translation start site. Using RNAase protection and primer extension, we identified the mRNA start 37 bp upstream from the beginning of the bek cDNA. The promoter activity was found to reside in a 1.3-kbp fragment upstream from the cDNA, and deletion mapping further localized the promoter to a 0.7-kbp fragment. The sequence of this region shows high G+C content (62%), which is particularly emphasized in the 200 bp upstream from the mRNA start (80% G+C). This region contains the CCGCCC, GGGCGG AND GGAGG motifs also found in promoters of other growth factor receptors. Neither TATA nor CAAT boxes were found near the RNA start site. The characterization of this promoter will allow studies of the regulation of expression of the FGFR2 during development and in pathophysiological states. The differences between the promoter sequence of the gene for FGFR2 (bek) and FGFR1 (flg) may explain their differential expression during development.

Animals↗
PubMed1992

Fibroblast growth factor receptor-4 shows novel features in genomic structure, ligand binding and signal transduction.

Fibroblast growth factor (FGF) receptor (FGFR) gene family consists of at least four receptor tyrosine kinases that transduce signals important in a variety of developmental and physiological processes related to cell growth and differentiation. Here we have characterized the binding of different FGFs to FGFR-4. Our results establish an FGF binding profile for FGFR-4 with aFGF having the highest affinity, followed by K-FGF/hst-1 and bFGF. In addition, FGF-6 was found to bind to FGFR-4 in ligand competition experiments. Interestingly, the FGFR-4 gene was found to encode only the prototype receptor in a region where both FGFR-1 and FGFR-2 show alternative splicing leading to differences in their ligand binding specificities and to secreted forms of these receptors. Ligands binding to FGFR-4 induced receptor autophosphorylation and phosphorylation of a set of cellular polypeptides, which differed from those phosphorylated in FGFR-1-expressing cells. Specifically, the FGFR-1-expressing cells showed a considerably more extensive tyrosine phosphorylation of PLC-gamma than the FGFR-4-expressing cells. Structural and functional specificity within the FGFR family exemplified by FGFR-4 may help to explain how FGFs perform their diverse functions.

Alternative Splicing↗
PubMed1992

Coexpression of FGF-5 and bFGF by the retinal pigment epithelium in vitro.

Members of the fibroblast growth factor (FGF) gene family have been proposed to play critical roles in the biology of the outer retina. In this study, in vitro cultures of human retinal pigment epithelial (RPE) cells were surveyed for the expression of FGF gene family members. Northern analysis provided evidence for the expression of the previously reported 7.0 and 3.7 kb basic FGF (bFGF) transcripts and for the 4.0 and 2.1 kb FGF-5 transcripts. Western analysis demonstrated the presence of three bFGF proteins ranging in size from 18 to 26 kDa and three FGF-5 proteins of molecular weights 28.5, 34, and 36 kDa. We were particularly interested in cellular mechanisms which might regulate the steady-state mRNA levels of these genes. It was determined that bFGF message levels decreased with increasing culture density, increased upon serum stimulation and when placed in contact with matrix components found in the extracellular matrix of RPE cells in vivo. In a similar fashion, the steady state mRNA levels for FGF-5 decreased with increasing culture density, increased upon serum stimulation, but appeared to be unaffected by matrix contact.

Blotting, Northern↗
PubMed1992

Regulation of fibroblast growth factor-like protein(s) in the androgen-responsive human prostate carcinoma cell line LNCaP.

Growth of the normal and malignant prostate is known to be regulated by androgens. Part of their effect has been suggested to be mediated through coordinated regulation of secreted growth factors with autocrine function. We now examine the biological role of preferentially paracrine acting factors in growth control of prostate cancer, i.e. fibroblast growth factor(s) (FGF). Coculture experiments using the androgen-responsive human prostate carcinoma cell line LNCaP as feeder cells and the FGF-dependent human adrenal carcinoma SW-13 cell line as target cells show that (i) LNCaP cells induce growth of SW-13 cells, (ii) even higher stimulation of SW-13 cells is seen in the presence of androgen treated LNCaP cells and (iii) a specific anti-bFGF antibody inhibits growth of SW-13 cells induced by androgen treated LNCaP cells; no proliferation of SW-13 cells occurs in the absence of LNCaP cells. Partial purification of the secretory products of LNCaP cells was performed by affinity chromatography using a heparin sepharose column. Fractions were tested for biological activity in a soft agar assay with SW-13 cells. Several activities could be detected, the main activity was eluted with about 1.5 M NaCl. These data suggest that androgen treatment of LNCaP cells leads to enhanced secretion of proteins which belong to the FGF-family.

Adrenal Gland Neoplasms↗
PubMed1992

Characterization of the murine BEK fibroblast growth factor (FGF) receptor: activation by three members of the FGF family and requirement for heparin.

The bek gene encodes a member of the high-affinity fibroblast growth factor receptor family. The BEK/FGFR-2 receptor is a membrane-spanning tyrosine kinase with the typical features of FGF receptors. We have cloned a murine bek cDNA and expressed it in receptor-negative Chinese hamster ovary cells and in 32D myeloid cells. The BEK receptor expressed in Chinese hamster ovary cells binds acidic FGF, basic FGF, and Kaposi FGF equally well but does not bind keratinocyte growth factor or FGF-5 appreciably. Upon treatment with basic FGF or Kaposi FGF, the BEK receptor is phosphorylated and a mitogenic response is achieved. Heparan sulfate proteoglycans have been shown to play an obligate role in basic FGF binding to the high-affinity FLG receptor. Unlike the BEK-expressing Chinese hamster ovary cells, 32D cells expressing the BEK receptor require the addition of exogenous heparin in order to grow in the presence of basic FGF or Kaposi FGF. We show that the addition of heparin greatly enhances the binding of radio-labeled basic FGF to the receptor. Thus the BEK receptor, like FLG, also requires an interaction with heparan sulfate proteoglycans to facilitate binding to its ligands.

Amino Acid Sequence↗
PubMed1992

Repression of myogenic differentiation by aFGF, bFGF, and K-FGF is dependent on cellular heparan sulfate.

We have proposed a model in which fibroblast growth factor (FGF) signalling requires the interaction of FGF with at least two FGF receptors, a heparan sulfate proteoglycan (HSPG) and a tyrosine kinase. Since FGF may be a key mediator of skeletal muscle differentiation, we examined the synthesis of glycosaminoglycans in MM14 skeletal muscle myoblasts and their participation in FGF signalling. Proliferating and differentiated MM14 cells exhibit similar levels of HSPG, while differentiated cells exhibit reduced levels of chondroitin sulfate proteoglycans and heparan sulfate chains. HSPGs, including syndecan, present in proliferating cells bind bFGF, while the majority of chondroitin sulfate and heparan sulfate chains do not. Treatment of skeletal muscle cells with chlorate, a reversible inhibitor of glycosaminoglycan sulfation, was used to examine the requirement of sulfated proteoglycans for FGF signalling. Chlorate treatment reduced glycosaminoglycan sulfation by 90% and binding of FGF to high affinity sites by 80%. Chlorate treatment of MM14 myoblasts abrogated the biological activity of acidic, basic, and Kaposi's sarcoma FGFs resulting in terminal differentiation. Chlorate inhibition of FGF signalling was reversed by the simultaneous addition of sodium sulfate or heparin. Further support for a direct role of heparan sulfate proteoglycans in fibroblast growth factor signal transduction was demonstrated by the ability of heparitinase to inhibit basic FGF binding and biological activity. These results suggest that activation of FGF receptors by acidic, basic or Kaposi's sarcoma FGF requires simultaneous binding to a HSPG and the tyrosine kinase receptor. Skeletal muscle differentiation in vivo may be dependent on FGFs, FGF tyrosine kinase receptors, and HSPGs. The regulation of these molecules may then be expected to have important implications for skeletal muscle development and regeneration.

Animals↗
PubMed1992

Acidic and basic fibroblast growth factors in adult rat heart myocytes. Localization, regulation in culture, and effects on DNA synthesis.

Basic fibroblast growth factor (bFGF) and acidic fibroblast growth factor (aFGF) are involved in the induction of embryonic mesoderm, angiogenesis, neuronal differentiation, and proliferation and survival of many cell types. In cardiac myocytes their roles are not well understood. Effects of fibroblast growth factors on reexpression of fetal actin genes have been reported. In freshly isolated adult rat cardiac myocytes, bFGF mRNA was not detectable by in situ hybridization, although the cells contained significant amounts of bFGF and aFGF as quantified by radioimmunoassays, mitogen assays with immunoneutralization, and Western blotting. After culturing, bFGF mRNA was detected (aFGF mRNA was not studied), and the cells contained 2.5-fold more bFGF and 60% more aFGF than freshly isolated cells. The FGFs were not found in conditioned medium. They were localized, especially in cultured cells, to the nucleus. Cultured myocytes bound fourfold more 125I-FGF than freshly isolated cells and expressed the fibroblast growth factor R-1 (flg) gene. The addition of bFGF or aFGF in serum-free medium to pure populations of myocytes (after 10 days in culture, at which time they are spread, beating, and multinucleated) led to increased thymidine incorporation. Expression of fibroblast growth factors and fibroblast growth factor receptors by adult cardiac myocytes that survive the shock and "dedifferentiation" of culturing may contribute to DNA synthesis and, by analogy, to other cell types, to regulation of ribosomal and actin genes, and to cell survival. These possibilities and their in vivo relevance will require further study.

Animals↗
PubMed1992

A time course for the focal elevation of synthesis of basic fibroblast growth factor and one of its high-affinity receptors (flg) following a localized cortical brain injury.

Traumatic injury to the CNS initiates transient and unsuccessful regeneration of damaged neural pathways, accompanied by reactive gliosis, angiogenesis, and deposition of a dense fibrous glial/meningeal scar at the wound site. Basic fibroblast growth factor (basic FGF) is a CNS protein with potent effects on neurons, glia, fibroblasts, and vascular endothelial cells. Hybridization and immunocytochemical methods were used to examine temporal and spatial changes in distribution and levels of basic FGF protein and mRNA and also of its receptor mRNA (flg), following a defined wound to the cerebral cortex of adult rat brains. In the injured brain, a rapid, transient increase in basic FGF mRNA and protein is readily detectable within 7 d of surgery and thereafter declines in the tissues bordering the lesion. The increased expression is localized to multiple cell types including macrophages, neurons, astrocytes, and vascular endothelial cells. The changes in immunoreactive basic FGF parallel changes in the bioactivity of extracted heparin-binding proteins, which include basic FGF. Focal increases in flg mRNA appear 7 d after injury and subside by 14 d. The changes in local basic FGF synthesis, concentration, localization, and bioactivity suggest that this growth factor may contribute to the cascade of cellular events that occur in CNS wound repair.

Animals↗
PubMed1992

A novel form of fibroblast growth factor receptor 2. Alternative splicing of the third immunoglobulin-like domain confers ligand binding specificity.

The fibroblast growth factor receptor 2 (FGFR2) gene is expressed as alternatively spliced mRNAs that encode bacterially expressed kinase, the keratinocyte growth factor receptor, or K-sam. We have now isolated a novel FGFR2 cDNA that is identical with the previously cloned human bacterially expressed kinase, except in the third immunoglobulin-like domain. The ligand binding properties of FGFR2 were studied by expressing the protein in rat L6 muscle myoblasts. Unlike human bacterially expressed kinase which binds acidic and basic FGF with similar affinities, FGFR2 bound acidic FGF with approximately 1000-fold higher affinity than basic FGF. These results indicate that alternative splicing of the FGFR2 gene in the region encoding the carboxyl-terminal half of the third immunoglobulin domain determines the ligand specificity of this group of receptors.

Alternative Splicing↗
PubMed1992

EGF, EGF receptor, basic FGF, TGF beta-1, and IL-1 alpha mRNA in human corneal epithelial cells and stromal fibroblasts.

We sought to determine whether human corneal epithelial cells and stromal fibroblasts synthesize messenger RNAs (mRNA) coding for epidermal growth factor (EGF), EGF receptor, basic fibroblast growth factor (basic FGF), transforming growth factor-beta 1 (TGF-beta 1), and interleukin-1 alpha (IL-1 alpha). Total cellular RNA was extracted from cultured stromal fibroblasts and ex vivo and cultured corneal epithelial cells. Oligo dt-primed complementary DNA (cDNA) was synthesized from each RNA sample. The polymerase chain reaction (PCR) was used to amplify sequences for EGF, EGF receptor, basic FGF, TGF-beta 1, IL-1 alpha, and beta actin from cDNA samples from each cell type. Southern blots of the PCR products were probed with oligonucleotides complementary to internal sequences within each of the amplified products. The amplification products were shown to be specific. For each modulator, the amplification product of the expected size was identified with at least one specific, alternative amplification product. The alternative splicing products suggest that there may be alternative mRNA splicing for each of the modulators studied. Differences were noted in the IL-1 alpha specific amplification products in stromal fibroblasts compared to corneal epithelial cells. EGF and EGF receptor mRNA production in human corneal epithelial cells and stromal fibroblasts suggest an autocrine role for EGF in the physiology of each of these cell types.

Adolescent↗
PubMed1992

Cytokine regulation of nerve growth factor-mediated cholinergic neurotrophic activity synthesized by astrocytes and fibroblasts.

The neurotrophic activity of astrocytes and fibroblasts and its regulation by various cytokines were investigated. Astrocyte conditioned medium (ACM) enhanced the survival of neurons and the proliferation of astrocytes in embryonic cortical cultures grown in serum-free defined medium. However, these results were not affected by acidic fibroblast growth factor, interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF alpha), and transforming growth factor-beta 1. In contrast, ACM induced choline acetyltransferase expression in septal cholinergic neurons via nerve growth factor (NGF)-dependent and -independent mechanisms. However, neither acidic nor basic fibroblast growth factor is involved in this biological activity in ACM. The cytokines listed above mainly stimulate NGF-mediated cholinergic neurotrophic activity in ACM. A combination of IL-1 beta and TNF alpha significantly enhanced choline acetyltransferase activity in septal neurons co-cultured with astrocytes, and this effect was found to be mediated by NGF produced by activated astrocytes. Effects of astrocytes on GABAergic neurons were also examined. ACM was found to increase glutamate decarboxylase activity in neuronal cultures from septum in the presence of Ara-C. However, the cytokines did not enhance this activity in ACM. Moreover, a combination of IL-1 beta and TNF alpha had no effect on glutamate decarboxylase activity in septal neurons co-cultured with astrocytes. In a final set of experiments, cholinergic neurotrophic activity in skin-derived fibroblast conditioned medium (FCM) was examined. FCM was found to possess biological activity similar to that of ACM on septal neurons grown in serum-free defined medium with Ara-C. The cytokines also enhanced NGF-mediated cholinergic neurotrophic activity in FCM. Astrocytes and fibroblasts were found to possess NGF-type and non-NGF-type cholinergic neurotrophic activity, and various cytokines were found to regulate the NGF-type cholinergic neurotrophic activity in both types of cells. NGF produced by astrocytes and fibroblasts that are activated by cytokines is likely to be important for development and regeneration of NGF-sensitive neurons in the central and peripheral nervous systems.

Animals↗
PubMed2026

Mesenchymal Stem Cell-Derived Exosomes Combined With 3-Dimensional Hyaluronan-Based Scaffold Promote Tendon-to-Bone Tunnel Healing.

PURPOSE: Tendon-to-bone healing remains a major clinical challenge due to poor regenerative capacity at the enthesis. This study aimed to evaluate the effects of mesenchymal stem cell-derived exosomes combined with a 3-dimensional hyaluronan-based scaffold on graft healing within bone tunnels. This study was conducted in accordance with the ARRIVE (Animal Research: Reporting of In Vivo Experiments) guidelines. METHODS: A total of 128 tendon-bone models were created in 64 Sprague-Dawley rats, randomized into four groups: control, exosome-only, scaffold-only, and exosome-loaded scaffold. At weeks 4 and 8 postoperatively, samples were analyzed histologically (hematoxylin-eosin, Masson Trichrome), immunohistochemically (fibroblast growth factor 2, bone morphogenetic protein 2), and biomechanically (maximum failure load). RESULTS: At both time points, the exosome-loaded scaffold group demonstrated significantly enhanced vascularization, cellular activity, and collagen fiber continuity and parallelism compared to all other groups (P < .05). Fibroblast growth factor 2 and bone morphogenetic protein 2 expression levels were highest in the exosome-loaded scaffold group, indicating early activation of proregenerative pathways. Biomechanically, this group also exhibited the greatest maximum failure load (15.64 &#xb1; 0.86 N at week 4; 22.97 &#xb1; 2.86 N at week 8), suggesting superior tendon-to-bone integration. The exosome-only group showed delayed but comparable improvements by week 8. CONCLUSIONS: Combining mesenchymal stem cell-derived exosomes with a 3-dimensional hyaluronan-based polycaprolactone/tricalcium phosphate scaffold enhances early and sustained healing at the tendon-bone interface. This cell-free, biocompatible strategy significantly improves vascularization, growth factor expression, collagen organization, and mechanical strength. These findings support its potential as a clinically translatable approach for improving tendon-to-bone healing outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Animals↗
PubMed1992

Cooperative regulation of nerve growth factor synthesis and secretion in fibroblasts and astrocytes by fibroblast growth factor and other cytokines.

Acidic fibroblast growth factor (aFGF) enhances nerve growth factor (NGF) synthesis by astrocytes obtained from various brain regions. NGF secretion by fibrous-shaped astrocytes transformed by dibutyryl-cAMP (db-cAMP) pretreatment was less than that by untreated astrocytes. However, aFGF also enhanced NGF secretion by fibrous-shaped astrocytes. The effects of various kinds of intracellular signaling modulators on NGF synthesis were examined. None of the following second messenger effectors had an effect on NGF synthesis: protein kinase C (PKC) agonist (phorbol myristate acetate (PMA)) or antagonist (sphingosine (SP)). LiCl, and ionomycin (Iono). Further, increases of intracellular cAMP by forskolin (FK) or db-cAMP have no significant effect on NGF synthesis in astrocytes under a standard culture condition. However, NGF synthesis by astrocytes in the presence of aFGF was significantly enhanced by db-cAMP, but not by FK or sodium butyrate. These results indicate that an excessive amount of cAMP enhances the effect of aFGF on NGF synthesis in astrocytes. NGF synthesis in astrocytes was not affected by treatment with anti-aFGF or anti-bFGF neutralizing antibodies, indicating that FGFs are not involved in the autocrine regulation of NGF synthesis in astrocytes. Transforming growth factor-beta 1 (TGF-beta 1), which inhibits some effects of FGFs, increased NGF synthesis in concert with aFGF. Furthermore, the highest NGF synthesis was observed when astrocytes were stimulated by all of the following cytokines: aFGF, interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha) and TGF-beta 1. The mechanism regulating NGF synthesis in fibroblasts obtained from prenatal rat skin was also investigated. Acidic FGF, basic FGF (bFGF), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), transforming growth factor-alpha (TGF-alpha), TGF-beta 1, IL-1 beta, and TNF-alpha were found to be regulators of NGF synthesis in skin fibroblasts. Among these cytokines, aFGF is the most potent regulator of NGF synthesis in fibroblasts. NGF synthesis by skin fibroblasts, either in the presence or absence of aFGF, was not modified by any of the following: FK, PMA, SP, LiCl, and Iono. However, db-cAMP significantly enhanced NGF synthesis in both conditions. Sodium butyrate enhanced NGF synthesis in the presence of aFGF, but not in the absence of aFGF. These results suggest that an excessive amount of cAMP and butyrate moiety regulate NGF synthesis in skin fibroblasts in different ways.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMedDate not supplied

Receptor phenotype underlies differential response of hepatocytes and nonparenchymal cells to heparin-binding fibroblast growth factor type 1 (aFGF) and type 2 (bFGF).

Heparin-binding fibroblast growth factors (HBGF) have been implicated in the regeneration of both parenchymal and nonparenchymal cells of the liver. The response to and phenotype of hepatocyte receptors for HBGF-1 (acidic fibroblast growth factor) and HBGF-2 (basic fibroblast growth factor) were compared to keratinocytes, fibroblasts, and endothelial cells. HBGF-1 stimulated DNA synthesis in hepatocytes, keratinocytes, fibroblasts, and endothelial cells whereas activity of HBGF-2 was limited to fibroblasts and endothelial cells. HBGF-2 antagonized the mitogenic activity of HBGF-1 for hepatocytes and keratinocytes. Hepatocytes and keratinocytes exhibited both high- and low-affinity, nonmatrix receptor sites for HBGF-1, but only low-affinity sites for HBGF-2. The mesenchymal cells displayed only high-affinity sites for both HBGF-1 and HBGF-2. Northern blot and immunochemical analysis revealed that the expression of HBGF receptor genes bek and flg are partitioned between normal hepatocytes and nonparenchymal cells, respectively. Expression of epithelial cell-specific, mesenchymal cell-derived HBGF-7 (keratinocyte growth factor) mRNA in regenerating liver tissue was undetectable relative to HBGF-1. The results support a multifunctional role of HBGF-1 acting through different receptor phenotypes in hepatocyte and nonparenchymal cells during liver regeneration.

Animals↗
PubMed1992

Mitotic potential of adult rat oligodendrocytes in culture.

The proliferation of adult oligodendrocytes (OLGs) was examined in response to membrane bound and soluble mitogens. OLGs were isolated according to Vick, et al., J Neurosci Res 25:524-534, 1990, and co-cultured with dorsal root ganglia (DRGs). Less than 5% of the total cells incorporated a 48 hr pulse of 3H thymidine during the first 4 days of co-culture. From day 4 to day 6 there was a dramatic increase in proliferation which reached a plateau at 40% and gradually decreased to 25% from days 10 to 20 of co-culture. Axolemma-enriched fractions (AEF) were weak mitogens for OLGs (less than 5% proliferation after 7 days of stimulation), however, heparin extracts of AEF were five-fold more mitogenic than the AEF from which they were derived. Basic and acidic fibroblast growth factor were effective mitogens for the adult OLGs (labelling indices of 28% and 12%, respectively) provided that the cells were treated for 7 days with the growth factor and that the cells had been in culture for at least 14 days. Other soluble growth factors (IL-2 and PDGF) gave no mitotic response. We conclude that adult OLGs are mitotically responsive to mitogens provided that (1) the adult OLG has been cultured for sufficient time (14 days, acidic or basic fibroblast growth factor); (2) the axonal mitogen is allowed to interact with the OLG for a sufficient time (neuritic mitogen); and (3) the axonal mitogen is presented to the OLG in an activated form (AEF-heparin extract).

Animals↗