Upregulation of fibroblast growth factor-receptor messenger RNA expression in rat brain following transient forebrain ischemia

Recently, we demonstrated that transient forebrain ischemia in rats leads to an early and strong induction of basic fibroblast growth factor (bFGF) synthesis in astrocytes in the injured brain regions. In this study, in order to clarify the targets of such raised endogenous bFGF levels, the messenger RNA (mRNA) expression of its receptors (flg and bek) in the hippocampus following transient forebrain ischemia induced by four-vessel occlusion for 20 min was investigated using an in situ hybridization technique. Transient forebrain ischemia induced an increase in the number of flg mRNA-positive cells from an early stage (24 h after ischemia) in the hippocampal CA1 subfield where delayed neuronal death occurred later (48-72 h after ischemia). This increase became more marked with the progression of neuronal death and was still evident in the same area 30 days later. The time course of the appearance and distribution pattern of flg mRNA-positive cells in the CA1 subfield were quite similar to those of bFGF mRNA-positive cells. On the other hand, in situ hybridization for bek mRNA showed only slight and transient (observed 72 h and 5 days after ischemia) increases in the number of mRNA-positive cells in the CA1 subfield following ischemia. The use of in situ hybridization and glial fibrillary acidic protein immunohistochemistry in combination demonstrated that the cells in the CA1 subfield that exhibited ischemia-induced flg or bek mRNA expression were astrocytes. These data indicate that transient forebrain ischemia induces upregulation of fibroblast growth factor-receptor expression, accompanied by increased bFGF expression in astrocytes, and suggest that the increased astrocytic bFGF levels in injured brain regions act on the astrocytes via autocrine systems and are involved in the development and maintenance of astrocytosis.

Influence of transforming growth factor beta 1 and other growth factors on basic fibroblast growth factor level and proliferation of cultured human prostate-derived fibroblasts

Basic fibroblast growth factor (bFGF) has been identified in the human prostate. The level of bFGF has been reported to be elevated in benign prostatic hyperplasia (BPH), compared with normal prostate, suggesting that the growth factor may play a role in this disease of the prostate. Basic FGF is a mitogen for cultured human prostate-derived fibroblasts (PF). PF also synthesize bFGF, suggesting that growth regulation of these cells may be under autocrine control. The current study was undertaken to identify factors that affect PF proliferation and bFGF expression. Transforming growth factor beta 1 (TGF-beta 1) inhibited PF proliferation. The inhibition by TGF-beta 1 was partially overcome by bFGF but not by epidermal growth factor (EGF), platelet-derived growth factor (PDGF), insulin-like growth factor type 1 (IGF-1), or insulin. Incubation of PF with TGF-beta 1 increased bFGF mRNA and immunoreactive bFGF levels in a dose- and time-dependent fashion. None of the other growth factor studies affected bFGF levels. PF were also found to express TGF-beta 1 mRNA, the level of which was increased two- to fivefold by TGF-beta 1. These observations suggest that PF proliferation is controlled by the interaction of two different growth factors. It is possible that bFGF/TGF-beta imbalance in favor of cell proliferation promotes prostatic stromal hyperplasia.

Expression of growth factor peptides and their receptors in neuroendocrine tumors of the digestive system

Neuroendocrine tumors of the digestive system are slow growing neoplasms which often present with pronounced fibrosis around tumor cells and in the peritoneal cavity. In this report 30 midgut carcinoids and endocrine pancreatic tumors were examined for the expression of peptide growth factors and their receptors, both by immunohistochemistry and in situ hybridization. Our data indicate that multiple peptide growth factors, PDGF, TGF-beta, and bFGF are expressed by these tumors. PDGF was expressed on tumor cells and stroma in 70% of tissues examined. PDGF alpha-receptor was seen on clusters of tumor cells and occasionally on adjacent stroma, whereas PDGF beta-receptor was seen only in the stroma. Our data suggest that PDGF may be involved in the autocrine stimulation of tumor cells and stimulation of stromal cell growth through paracrine and possibly autocrine mechanism. In addition, tumor tissues express all three isoforms of TGF-beta in more than half of the tissues examined. Tumor cells produce small latent complexes causing an escape from potent inhibitory effect of TGF-beta and stimulation of stromal cell growth and matrix deposition through paracrine mechanism. bFGF, a potent stimulant of endothelial cell growth, was expressed by all tumor tissues examined. Our data suggest that multiple peptide growth factors may have an important role in tumor progression and desmoplastic reaction accompanying these tumors.

Basic fibroblast growth factor production in vitro by macrophages exposed to Dacron and polyglactin 910

Macrophage activation by implanted blood-contacting biomaterials modulates smooth muscle cell and endothelial cell ingrowth. The present study evaluates the in vitro interactions between Dacron or polyglactin 910 with macrophages derived from rabbits fed either normal or atherogenic diets. Peritoneal macrophages were cultured in the presence or absence (negative controls) of either biomaterial for 7 weeks. Conditioned media was evaluated for mitogenic activity using a rabbit aortic smooth muscle cell bioassay with or without preincubation with neutralizing anti-basic-FGF antibody. Results demonstrated increased mitogen release from macrophages harvested from the atherosclerotic rabbits. Only macrophages harvested from normal diet fed rabbits increased their mitogen release following exposure to either polyglactin 910 (p < 0.05) or to Dacron (p < 0.005) over controls. The stimulation of mitogen release by polyglactin 910 did not significantly exceed that in response to Dacron. In rabbits fed normal diets neutralization with the anti-basic-FGF antibody inhibited 100% of the Dacron induced mitogen release as compared to 36% of the polyglactin 910 induced mitogen release (p < 0.01). These results demonstrate significant induced mitogen release from macrophages exposed to biomaterials in vitro, much of the smooth muscle cell mitogen represented by basic-FGF.

Basic fibroblast growth factor (bFGF) gene expression and protein production during pubertal development of the seminiferous tubule: follicle-stimulating hormone-induced Sertoli cell bFGF expression

The potential role of basic fibroblast growth factor (bFGF) as a mediator of cell-cell interactions in the growth and development of the testis was examined. Nuclease protection analysis was used to evaluate bFGF gene expression in the testis and other male reproductive tract tissues. bFGF expression was evident in seminal vesicle, prostate, epididymis, and, at low levels, testis of 20-day-old rats. The developmental expression of bFGF in whole testis and isolated somatic cells types was determined. Mesenchymal-derived peritubular cells and epithelial-like Sertoli cells were isolated from prepubertal, midpubertal, and late pubertal rat testes. In whole testis, bFGF expression is predominant early in prepubertal testicular development and decreases with sexual maturity. Both freshly isolated peritubular and Sertoli cells express bFGF at relatively constant levels during pubertal development, with a slight suppression at the late pubertal stages. Freshly isolated mature Leydig cells also expressed low levels of bFGF. Cultured Sertoli and peritubular cells produced bFGF-like proteins, including 18- and 24-kilodalton forms. Interestingly, FSH increased Sertoli cell bFGF gene expression and protein production. Previously, FSH and bFGF have been shown to stimulate immature Sertoli cell growth. The results of the current study suggest that the ability of FSH to regulate testis and Sertoli cell proliferation may in part be indirectly mediated through the local production and action of bFGF. bFGF has also previously been shown to localize in developing germinal cells. Therefore, FSH-induced Sertoli cell bFGF expression may mediate Sertoli-germinal cell interactions involved in the control of the spermatogenic process. Observations demonstrate the presence of bFGF at a time coinciding with active growth of the somatic cell populations of the seminiferous tubule. Potential roles for bFGF in the seminiferous tubule to consider include angiogenesis of the tubule, prepubertal Sertoli cell proliferation, and mediating Sertoli-germinal cell interactions.

Differential expression of acidic and basic FGF in the rat substantia nigra during development

Both acidic (aFGF) and basic (bFGF) fibroblast growth factors have been shown to be present in the adult rat ventral mesencephalon and to exert effects on cultured mesencephalic cells. In the present study we have examined the expression of aFGF and bFGF in the rat ventral mesencephalon at various stages of development. bFGF was present at all ages examined [embryonic day 16 (E16) to postnatal day 90 (P90)]. In contrast, aFGF was not detectable at embryonic and early postnatal ages, but was observed at later (P20, P60, P90) postnatal stages. These data suggest that aFGF and bFGF may have functions in mesencephalic dopamine neurones in different stages of development.

Augmented production of heparin-binding mitogenic proteins by preadipocytes from massively obese persons

Basic fibroblast growth factor (bFGF) stimulates the replication of preadipocytes and inhibits their differentiation. In this study we explored whether the same or related polypeptides were produced locally and acted by paracrine/autocrine mechanisms in adipose tissue. Omental preadipocytes from 7 lean and 10 massively obese (> 170% reference) subjects were grown to confluence in subculture. Total RNA was hybridized with a synthetic deoxynucleotide for human bFGF. In the case of all cell strains, there was expression of two major bFGF transcripts, 7.0 and 3.7 kb. Although there was considerable variation in the degree of expression, preadipocytes from massively obese subjects revealed much greater expression than did cells from the lean (P < 0.001). In studies of conditioned media prepared with preadipocytes, the presence of proteins belonging to the heparin-binding (fibroblast) growth factor family was indicated by Western blot analysis, for a 66-kD protein with anti-(1-24)bFGF, and for a 32-kD protein with anti-(40-63)bFGF antibodies. The relative quantity of the 66-kD protein correlated with body mass index at r = 0.72. bFGF-related proteins probably function normally to maintain an appropriate complement of adipocyte precursors. The augmented expression of heparin-binding growth factors in preadipocytes from some massively obese people probably contributes to the excessive cellularity of their fat depots.

Over-expression of fibroblast growth factors in Xenopus embryos

A number of forms of fibroblast growth factor (FGF) were over-expressed within Xenopus embryos by injection of synthetic FGF mRNAs into fertilized eggs. Injected embryos showed abnormalities in development which were mainly secondary to a disruption of gastrulation movements. The effects observed after injection of bFGF mRNA, however, were much less severe than those observed after injection of an altered form of bFGF mRNA which differs only by the addition of a signal sequence for secretion, or of another member of the FGF family, kFGF, which is normally efficiently secreted. All forms of FGF caused the induction of mesoderm in animal cap explants isolated from blastulae, but the amount of bFGF mRNA required to induce the formation of significant levels of mesoderm was higher by a factor of over a hundred than that of the FGFs which contain a signal sequence for secretion. Over-expressed bFGF accumulated in the nuclei of blastulae but did not necessarily cause mesoderm formation. These results show that FGFs must be secreted from the cells in which they are synthesised in order to act efficiently as mesoderm inducing factors and suggest that bFGF itself, which does not contain a signal sequence for secretion, is unlikely to be directly involved in mesoderm induction during early embryonic development.

BHK-21-derived cell lines that produce basic fibroblast growth factor, but not parental BHK-21 cells, initiate neuronal differentiation of neural crest progenitors

We present evidence that basic fibroblast growth factor (bFGF)-producing cells stimulate primary differentiation of neurons from neural crest progenitors. Baby hamster kidney (BHK-21) cells were stably cotransfected with plasmid pSV2/neo, which contains the gene conferring resistance to the neomycin analog G418 and expression vectors containing the human bFGF cDNA. Various clones, which differed in their bFGF production levels, were isolated. Homogeneous neural crest cells were cultured on monolayers of bFGF-producing, BHK-21-derived cell lines. While the parental BHK-21 cells, which do not produce detectable bFGF, had poor neurogenic ability, the various bFGF-producing clones promoted a 1.5- to 4-fold increase in neuronal cell number compared to the parental cells. This increase was correlated with the levels of bFGF produced by the different transfected clones, which ranged between 2.3 and 140 ng/mg protein. In contrast, no stimulation of neuronal differentiation was observed when neural crest cells were grown on monolayers of parental BHK cells transfected with plasmid pSV2/neo alone, or on a parental BHK-derived clone, which secretes high amounts of recombinant vascular endothelial growth factor (VEGF). Furthermore, the neuron-promoting ability of bFGF-producing cells could be mimicked by addition of exogenous bFGF to neural crest cells grown on the parental BHK line. A similar treatment of neural crest cells grown on laminin substrata, instead of BHK cells, resulted in increased survival of non-neuronal cells, but not of neurons (see also Kalcheim, C. 1989, Dev. Biol. 134, 1–10). Taken together, these results suggest that bFGF stimulates neuronal differentiation of neural crest cells by a cell-mediated signalling mechanism.

Expression of basic fibroblast growth factor, FGFR1 and FGFR2 in normal and malignant human breast, and comparison with other normal tissues

The expression of basic fibroblast growth factor (bFGF) and two of its receptors, FGFR1 and FGFR2, was detected using the polymerase chain reaction, and quantified by comparison to the relative amount of product obtained following co-amplification of the ubiquitous glyceraldehyde phosphate dehydrogenase transcript. Varying levels were found in the vast majority of both cancer and non-malignant breast biopsies as well as in samples of several other normal human tissues. Significantly less bFGF was present in cancers (P less than 0.0001). Similarly, FGFR2 product was also much less in cancer tissues (P = 0.0078), as was FGFR1 (P = 0.002). FGFR1 levels in cancers tended to be higher in those which were oestrogen receptor positive (P less than 0.06). Amplification of different coding regions showed evidence of variant forms of FGFR1 RNA. Cancers appeared to have a significantly greater proportion of PCR product corresponding to the region between the third immunoglobulin like domain and the tyrosine kinase domain (P = 0.046). Differential expression was observed in breast cell lines, with bFGF in the normal derived HBL100, HBR SV1.6.1 and 184A1 but little or none in ZR-75-1, MCF-7, T47D and MDA-MB-231. FGFR1 was present in most of these but FGFR2 was absent from T47D, MDA-MB-231 and HBL100. ZR-75-1 cells had a marked preponderance of FGFR1 variants lacking part of the coding sequence. Aberrant receptor processing may provide clues concerning the role of FGF's and their potential involvement in malignancy.

A rapid procedure for production of human basic fibroblast growth factor in Escherichia coli cells

Human basic fibroblast growth factor has been expressed in Escherichia coli cells at a level of 2-3 mg/l culture, using a rapid procedure which requires only simple DNA manipulative work. The recombinant material has the same potency as natural basic fibroblast growth factor from bovine pituitary glands.

Production of mitogenic factor(s) by ovine corpora lutea throughout the estrous cycle

To evaluate secretion of mitogenic factors by ovine corpora lutea (CL) at several stages of development, luteal explants from days 5 (n = 12 ewes), 10 (n = 6 ewes), and 15 (n = 6 ewes) of the estrous cycle were incubated in serum-free medium for 24 h. Luteal-conditioned media (LCM) were evaluated for their ability to stimulate proliferation of endothelial, BALB/3T3, and ovarian granulosa cells. After mitogenic activity of LCM from individual animals was evaluated, pools of LCM from each day of the estrous cycle were subjected to anion-exchange, cation-exchange, and heparin-affinity chromatography to characterize mitogenic activity. Pools of LCM also were utilized for ultrafiltration, heat-treatment, trypsin-treatment, and immunoneutralization studies. Results demonstrated that ovine CL secrete mitogenic activity that stimulates (P less than 0.01) proliferation of endothelial (135.7 +/- 5.3% of control) and granulosa cells (188.9 +/- 2.9%) but not 3T3 (103.2 +/- 2.5%) cells. Differences between stages of luteal development were not observed. The mitogenic activity bound to diethylaminoethyl-Sephacel and heparin-agarose, but not to carboxymethyl-Sepharose, indicating that ovine luteal mitogenic factor(s) is anionic and may belong to the heparin-binding growth factor (HBGF) family. In addition, the mitogenic activity was heat-labile, trypsin-sensitive, and appeared to have a M(r) greater than 100,000. Mitogenic activity for endothelial cells was partially neutralized with a specific antibody against HBGF-1 and was completely abolished with a specific antibody against HBGF-2. Moreover, HBGF-1 and HBGF-2 were immunolocalized in histological sections of CL from days 5 (n = 5 ewes), 10 (n = 5 ewes), and 15 (n = 5 ewes) after estrus. These findings are the first report of a major mitogenic factor(s) produced by cyclic ovine CL and indicate this factor is an HBGF-2-like molecule.

Phosphorothioate antisense oligonucleotides against basic fibroblast growth factor inhibit anchorage-dependent and anchorage-independent growth of a malignant glioblastoma cell line

Basic fibroblast growth factor (bFGF) is a broad spectrum mitogen for many cells of neuroectodermal origin, including glial cells. The human malignant glioblastoma cell line U87-MG expresses high steady state levels of the bFGF mRNA and contains abundant stores of biologically active bFGF protein. In the present study we have examined the contribution of endogenous bFGF to the autocrine growth of these cells. Using reverse transcription-polymerase chain reaction, U87-MG cells were shown to express the mRNAs for both bFGF and the bFGF receptor, confirming the existence of the basic requirements for an autocrine loop. Addition of 5 microM bFGF-specific antisense oligonucleotide to U87-MG cultures significantly inhibited the growth rate of these cells within 48 h and blocked proliferation beyond 2 days. The corresponding bFGF-specific sense oligonucleotide did not significantly inhibit cell proliferation over the course of these experiments. Similarly, antisense oligonucleotides significantly inhibited colony formation in soft agar, while the sense sequence was without effect. Western blotting with antihuman bFGF revealed that U87-MG cells synthesize three isoforms of bFGF, approximately 18, 23, and 25 kilodaltons (kDa) in size. The 23- and 25-kDa isoforms together comprise approximately 80% of the total cellular stores of bFGF. Antisense treatment for 4 days reduced the abundance of the 23- and 25-kDa isoforms by 64-74%, but had little effect on the 18-kDa isoform. The inhibitory effect of the antisense oligonucleotides on anchorage-dependent proliferation was reversed by the addition of recombinant 18-kDa human bFGF.(ABSTRACT TRUNCATED AT 250 WORDS)

Basic fibroblast growth factor production and growth factor receptors as potential targets for melanoma therapy

A number of growth factors can stimulate the proliferation of human malignant melanoma cell lines. We investigated the effects of exogenous growth factors including basic fibroblast growth factor (bFGF), epidermal growth factor, transforming growth factor-alpha, insulin, insulin-like growth factor-I (IGF-I), acidic fibroblast growth factor, platelet-derived growth factor, transforming growth factor-beta and nerve growth factor on six human metastatic melanoma cell lines. The mitogenic activity of each growth factor was tested using the [3H]thymidine incorporation assay. There was a variable response of the different cell lines to most growth factors. All of the melanoma cell lines tested responded to IGF-I. Furthermore, the effects of growth factors were additive, a combination of bFGF and IGF-I having the greatest effect on three melanoma cell lines tested. The quantitative radioimmunoassay for bFGF and [125I]bFGF binding assay revealed that all of these melanoma cell lines produced bFGF and expressed high affinity receptors for bFGF. A 20-mer antisense oligodeoxynucleotide against the AUG initiation site of the bFGF coding region inhibited the proliferation of Mel-Tang by 40% (p less than 0.0001) and that of SK-MEL-5 by 20% (p less than 0.005), suggesting that these cell lines are at least under partial autocrine control of proliferation by bFGF. The presence of bFGF receptors on a high percentage of melanoma cell lines makes these a potential target for melanoma therapy.

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.

Rat prostate cancer cell line-specific production and apparent secretion of heparin-binding growth factors

Cultured C3 and T5 AXC/SSh rat prostate cancer cells and their conditioned media contained 1000-fold more heparin-binding mitogens than did normal AXC/SSh rat prostates. Immunological analyses confirmed that rat ventral prostate contained only a 17.5 kilodalton (kDa) basic fibroblast growth factor (bFGF)-like mitogen. In contrast, combined immunological and metabolic radiolabeling analyses showed that C3 cells contained 23/24 and 14 kDa bFGF-like polypeptides, whereas the principal bFGF-like polypeptides of C3 cell conditioned medium were proteins having masses of 17.5 and 14 kDa. Identical analyses showed that T5 cells contained 17.5 and 14 kDa bFGF-like polypeptides, whereas the principal bFGF-like polypeptides of T5 cell conditioned medium were proteins having masses of 17.5, 16, and 14 kDa. We found that bFGF-like proteins of mass less than 17.5 kDa, which were present in conditioned medium, were not derived by proteolysis of higher molecular weight bFGF-like mitogens after these were processed into conditioned medium. Northern analyses showed that normal prostate and prostate cancer cells contained acidic fibroblast growth factor transcripts of 6.5 and 3.4 kilobases (kb) and bFGF transcripts of 6.0 and 2.5 kb. Prostate cancer cells also contained a 12-kb bFGF transcript that was not present in normal prostate. Southern analysis of restriction endonuclease-digested normal prostate or prostate cancer cell genomic DNA showed that the 12-kb bFGF transcript was not the product of a rearranged bFGF gene. Our data show that rat prostate cancer cells contain bFGF-like polypeptides of mass 14 to 23/24 kDa and suggest that these cells secrete bFGF-like polypeptides.

Basic fibroblast growth factor in cells derived from Dupuytren's contracture: synthesis, presence, and implications for treatment of the disease

Dupuytren's contracture (DC) is associated with fibroblast and endothelial cell proliferation. We have identified a fibroblast and endothelial cell mitogen, basic fibroblast growth factor (FGF), in cells derived from this tissue and characterized the effects of this growth factor on DC cells. Northern blot analysis of DC cells reveals the presence of basic FGF mRNA species, and the DC cells coexpress multiple forms of basic FGF. Radioreceptor assays establish that the DC cells have high-affinity binding sites for basic FGF and proliferate in response to exogenous recombinant basic FGF. Furthermore, a conjugate between saporin (a ribosome-inactivating protein) and basic FGF, which is cytotoxic to cells possessing the basic FGF receptor, is also cytotoxic to DC cells. The possibility that basic FGF-saporin could be a potential therapeutic agent for prevention of recurrence of the disease after surgery is discussed.

Beta-amyloid stimulates glial cells in vitro to produce growth factors that accumulate in senile plaques in Alzheimer's disease

The effects of a synthetic homolog of beta-amyloid (beta 1-42) on the secretion of interleukin-1 (IL-1) and basic fibroblast growth factor (bFGF) from cultures of microglia and astrocytes, cells that surround beta-amyloid-containing plaques in Alzheimer's disease, were examined. Our results show that beta-amyloid not only enhances glial cell secretion of these factors, it stimulates the proliferation and morphological transformation of microglia. Since IL-1 and bFGF are known to elevate the synthesis of the beta-amyloid precursor protein and other plaque components, it is suggested that in this way, cascades may arise that contribute to the process of plaque development.

Localization of basic fibroblast growth factor (bFGF) in a metastatic cell line (AT-3) established from the Dunning prostatic carcinoma of rat: application of a specific monoclonal antibody

Localization of basic fibroblast growth factor (bFGF) in a metastatic cell line, AT-3, established from the Dunning prostatic carcinoma of rat was determined by two immunological techniques using a specific monoclonal antibody against bFGF. Concentration of bFGF in cell extract was measured by sandwich radioimmunoassay (RIA) with heparin-Sepharose and 125I-labeled monoclonal antibody. bFGF concentration in the extract of AT-3 cells increased with increasing concentration of NaCl in extraction buffer. Localization of bFGF in AT-3 cells was determined by counting radioactivity of 125I-labeled monoclonal antibody binding to AT-3 cells before or after increasing permeability of the cells. The binding increased significantly by this treatment, indicating that bFGF within the cells was detected.

TNF alpha, IL-1 alpha and bFGF are implicated in the complex disease of GM-CSF transgenic mice

Transgenic mice aberrantly expressing the granulocyte-macrophage colony stimulating factor (GM-CSF) gene develop an unusual syndrome of blindness, tissue damage and wasting which is associated with accumulations of hemopoietic cells. In order to further characterize this disease state, we have used messenger RNA detection techniques to show that the genes for tumor necrosis factor (TNF alpha), interleukin-1 alpha (IL-1 alpha) and basic fibroblast growth factor (bFGF) are expressed at abnormally high levels in both macrophages and granulocytes in transgenic mice. Furthermore, since these cell types also express the GM-CSF transgene, it is likely that they are autocrine stimulated by GM-CSF. These observations raise the possibilities that, first, the expression of tumor necrosis factor alpha, interleukin-1 alpha and basic fibroblast growth factor in hemopoietic cells is a direct consequence of their autostimulation by GM-CSF, and second, that these cytokines may be responsible for some aspects of the transgenic mouse disease.

Basic fibroblast growth factor is synthesized and released by isolated ovine fetal growth plate chondrocytes: potential role as an autocrine mitogen

Basic fibroblast growth factor (basic FGF) is a mitogen for isolated epiphyseal growth plate chondrocytes. To determine whether basic FGF might function as an autocrine stimulus to longitudinal skeletal growth in utero, we investigated the synthesis and release of basic FGF by isolated growth plate chondrocytes from the ovine fetus, the expression of mRNA for a high affinity basic FGF receptor by these cells, and the contribution of endogenous basic FGF to the DNA synthetic rate of the cells in vitro. Chondrocytes were isolated from the proximal tibial growth plate of the lamb fetuses between 35 and 132 days' gestation using collagenase, and were cultured in monolayer before use between passages 3 and 6. Viability was confirmed over the duration of the experiments by the exclusion of trypan blue, and an absence of lactate dehydrogenase accumulation in conditioned medium. Immunocytochemistry of chondrocyte monolayers showed immunoreactive basic FGF to be present in the cytoplasm of approximately 80% of sub-confluent cells which was accompanied by pronounced nuclear staining in approximately 30% of cells. Serum-free, conditioned culture medium, extracellular matrix and chondrocyte cytoplasm contained 52 +/- 2 pM/micrograms DNA, 66 +/- 2 pM/micrograms DNA and 22 +/- 3 pM/micrograms DNA basic FGF, respectively (mean +/- S.E.M., n = 8 fetuses), for cells obtained from animals of 35-40 days' gestation when assessed by radioimmunoassay. Chondrocyte-conditioned medium increased endothelial cell proliferation in vitro (a specific bio-assay for basic FGF and related peptides); and the mitogenic activity was removed from conditioned medium by incubation with heparin-Sepharose demonstrating that this was due to heparin-binding protein(s). Western blot analysis of conditioned medium using a specific basic FGF antibody revealed a single immunoreactive protein of approximately 18 kDa molecular size. The appearance of radiommunoassayable basic FGF in conditioned medium, extracellular matrix, and chondrocyte cytoplasm observed during culture was blocked by co-incubation with cycloheximide. The levels of immunoreactive basic FGF present in each compartment decreased with gestational age as did basal DNA synthetic rate assessed by the incorporation of [3H] thymidine. Incubation of chondrocytes with transforming growth factor beta, resulted in a significant increase while exposure to insulin-like growth factors or insulin caused a decrease, in the content and release of basic FGF. Basic FGF presence was unaltered when medium was supplemented with varying amounts of glucose (2.7-16.7 mM). In situ hybridization on cell monolayers using a cRNA probe encoding the high affinity flg receptor for FGFs showed an abundant expression of mRNA for the receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization of bFGF mRNA in cyclic rat ovary, diethylstilbesterol primed rat ovary, and cultured rat granulosa cells

Evidence from in vitro studies strongly implicates basic fibroblast growth factor (bFGF) as a local regulator of ovarian function. However, the in vivo function of this growth factor in the ovary is uncertain. The objective of this study has thus been to investigate the biological role of bFGF in the rat ovary by monitoring bFGF gene expression using in situ hybridization in 3 systems; (1) the naturally cycling ovary, (2) ovaries of immature rats treated with diethylstilbesterol (DES), and (3) primary rat granulosa cell cultures. The rat estrus cycle can be divided into 4 stages as determined by vaginal cytology; diestrus, proestrus, estrus and metestrus. bFGF mRNA transcripts were localized to granulosa and theca cells of developing follicles during proestrus and estrus and in the corpus luteum following ovulation during metestrus. The estrogen analogue DES induced extensive in vivo folliculogenesis and high levels of bFGF mRNA in both granulosa and theca cells when compared to controls. Detectable levels of bFGF mRNA were also observed in primary granulosa cell cultures grown to high density. Employment of this in situ hybridization procedure has enabled the in vivo cellular sources of bFGF mRNA to be identified and the time course of expression during the estrus cycle to be monitored. The biological significance of this expression and the interplay between bFGF, extra- and intra-ovarian modulators are discussed.