Complementary DNA cloning and sequencing of rat ovarian basic fibroblast growth factor and tissue distribution study of its mRNA

Early coronary angiogenesis in response to thyroxine: growth characteristics and upregulation of basic fibroblast growth factor

Although a substantial coronary angiogenesis occurs after thyroid hormone treatment, its regulation and relationship to cardiac hypertrophy are not understood. This study was designed to determine (1) the onset of capillary proliferation, (2) the sites of capillary proliferation, and (3) whether basic fibroblast growth factor (bFGF) upregulation occurs in response to thyroxine administration. Male Sprague-Dawley rats were injected daily with L-thyroxine (T4, 0.2 mg/kg s.c.). Bromodeoxyuridine labeling of capillary endothelial cells increased during the first 24 hours of treatment and peaked after 2 days of treatment. Northern blot analysis revealed a slight increase in bFGF mRNA during this period, followed by a doubling of expression by 48 hours, at which time bFGF protein was also increased. In situ hybridization, used to localize bFGF mRNA, showed an increase in transcripts within 24 hours after T4. This enhancement was uniform in the epimyocardium and endomyocardium. Histochemical analysis (double staining for alkaline phosphatase and dipeptidyl peptidase) of frozen sections, used to discriminate capillary profiles as arteriolar and venular, respectively, showed that growth occurred in the latter, since the percentage of capillary profiles positive for dipeptidyl peptidase was higher than the control value after 4 days of T4 administration. These data indicate that in the thyroxine model of cardiac hypertrophy (1) capillary DNA synthesis occurs after a single injection of thyroxine, (2) capillary growth coincides with an upregulation in bFGF mRNA and increase in bFGF protein, and (3) proliferation occurs in the venular capillaries.

Preconditioning with bright light evokes a protective response against light damage in the rat retina

Constant exposure to bright light induces photoreceptor degeneration and at the same time upregulates the expression of several neurotrophic factors in the retina. At issue is whether the induced neurotrophic factors protect photoreceptors. We used a preconditioning paradigm to show that animals preconditioned with bright light became resistant to subsequent light damage. The preconditioning consisted of a 12-48 hr preexposure, followed by a 48 hr "rest phase" of normal cyclic lighting. The greatest protection was achieved by a 12 hr preexposure. Preconditioning induces a prolonged increase in two endogenous neurotrophic factors: basic fibroblast growth factor (bFGF) and ciliary neurotrophic factor (CNTF). It also stimulates the phosphorylation of extracellular signal-regulated protein kinases (Erks) in both photoreceptors and Müller cells. These findings indicate that exposure to bright light initiates two opposing processes: a fast degenerative process that kills photoreceptors and a relatively slower process that leads to the protection of photoreceptors. The extent of light damage, therefore, depends on the interaction of the two processes. These results also suggest a role of endogenous bFGF and CNTF in photoreceptor protection and the importance of Erk activation in photoreceptor survival.

Glutamate-stimulated proliferation of rat retinal pigment epithelial cells

We investigated the effects of glutamate on cell proliferation and the expression of basic fibroblast growth factor (bFGF) and its receptor (FGF-R1) mRNA in cultured rat retinal pigment epithelial (RPE) cells. The number of primary RPE cells was significantly higher after treatment with 0.2 to 1.0 mM glutamate (maximum at 1.0 mM) for 7 days than in controls. Glutamate-stimulated cell proliferation was abolished by (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), but not by 6,7-dinitroquinoxaline-2,3-dione or L(+)-2-amino-3-phosphonopropionic acid. Proliferation was increased to a similar extent by N-methyl-D-aspartate (NMDA), but not by kainate, alpha-amino-3-hydroxy-3-methyl-4-isoxazolepropionic acid or trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid. NMDA-receptor-like immunoreactivity was detected in most cells cultured. Treatment of cells with glutamate increased the level of bFGF mRNA and, to a lesser extent, that of FGF-R1 mRNA, which peaked 2 and 4 days, respectively, after glutamate was added. The increase in bFGF mRNA induced by glutamate was inhibited by MK-801. These findings suggest that glutamate might stimulate proliferation of RPE cells through activation of NMDA receptors and expression of bFGF and further suggest that glutamate may be involved in the proliferative changes of RPE cells in retinal wound healing.

Differential induction of nerve growth factor and basic fibroblast growth factor mRNA in neonatal and aged rat brain

Stimulation of glucocorticoid or beta-adrenergic receptors (BAR) has been shown to increase nerve growth factor (NGF) biosynthesis in adult rat brain. Little is known about the role of these receptors in the regulation of NGF expression in neonatal and aged brain. We have examined the effect of the synthetic glucocorticoid dexamethasone (DEX) and the BAR agonist clenbuterol (CLE) on the levels of NGF mRNA in neonatal (8 day old), adult (3 month old) and aged (24 month old) rats. By 3 h, DEX (0.5 mg/kg, s.c.) evoked a comparable increase in NGF mRNA in the cerebral cortex and hippocampus in both 8-day and 3-month-old rats. In contrast, CLE (10 mg/kg, i.p.) failed to change NGF mRNA levels in neonatal rats, while increasing (2-3-fold) NGF mRNA levels in the cerebral cortex of adult rats. In 24-month-old rats, both DEX and CLE elicited only a modest increase in NGF mRNA. This increase was, however, anatomically and temporally similar to that observed in adult animals. The weak effect of DEX or CLE was not related to a down-regulation of receptor function because both DEX and CLE were able to elicit a comparable increase in the mRNA levels for basic fibroblast growth factor (FGF2) in neonatal, adult and aged rat brain. Our data demonstrate that induction of NGF expression by neurotransmitter/hormone receptor activation varies throughout life and suggest that pharmacological agents might be useful tools to enhance trophic support in aging.

Regulation of astroglial-derived dopaminergic neurotrophic factors by interleukin-1 beta in the striatum of young and middle-aged mice

Interleukin-1 beta (IL-1 beta) can induce dopaminergic axonal sprouting in the denervated striatum of parkinsonian animals. In order to determine whether IL-1 beta effects on dopaminergic axonal sprouting are mediated by the induction of astroglial-derived dopaminergic neurotrophic factors, effects of IL-1 beta treatment on acidic and basic fibroblast growth factor (aFGF and bFGF) and glial cell line-derived growth factor (GDNF) gene expression were examined in primary striatal astrocyte cultures and after in vivo administration. We found a selective induction of bFGF mRNA synthesis but not aFGF or GDNF mRNA after IL-1 beta treatment both in vitro and in vivo. This suggests that bFGF may be the putative endogenous dopaminergic neurotrophic factor mediating lesion-induced plasticity of dopamine neurons. In addition, to determine why recovery from injury becomes reduced with age, we examined whether there was an aging-associated decline in the ability of IL-1 beta to induce the synthesis of neurotrophic factors in middle-aged animals compared to young mice. Interestingly, IL-1 beta stimulated a greater induction in bFGF mRNA levels in the middle-aged mice compared to young mice. These results suggest that the regulation of bFGF and possibly its receptor signaling efficacy may vary as the brain ages.

Physical exercise induces FGF-2 and its mRNA in the hippocampus

Clinical and experimental evidence indicate that physical activity has a positive impact on brain function; however, the molecular bases for how exercise affects the structure and function of the brain are largely unknown. We have investigated the influences of variable periods of voluntary wheel-running on the expression of basic fibroblast growth factor and its mRNA in various brain regions. Nuclease protection assays revealed that the hippocampus was the only region examined exhibiting changes in FGF-2 mRNA as a result of exercise. FGF-2 mRNA increased to reach a peak by the 4th night of wheel-running. FGF-2 immunoreactivity, normally located in the perinuclear area of astrocytes, following exercise became stronger and appeared to spread to the cytoplasm and processes of astrocytes. Quantification of the FGF-2-immunoreactive astrocytes showed an increase in density between 2 and 4 nights of running in discrete regions of the hippocampus. These results demonstrate that exercise regulates FGF-2 expression and suggest that growth factors are likely mediators of the positive effects of exercise on the brain.

Characterization and tissue-specific expression of the rat basic fibroblast growth factor antisense mRNA and protein

An RNA transcribed from the antisense strand of the FGF-2 gene has been implicated in the regulation of FGF-2 mRNA stability in amphibian oocytes. We have now cloned and characterized a novel 1. 1-kb mRNA (fgf-as) from neonatal rat liver. In non-central nervous system (CNS) tissues the fgf-as RNA is abundantly expressed in a developmentally regulated manner. The FGF-AS cDNA contains a consensus polyadenylylation signal and a long open reading frame (ORF) whose deduced amino acid sequence predicts a 35-kDa protein with homology to the MutT family of nucleotide hydrolases. Western blot analysis with antibodies against the deduced peptide sequence demonstrates that the FGF-AS protein is expressed in a broad range of non-CNS tissue in the postnatal period. In the developing brain, the abundance of sense and antisense transcripts are inversely related, suggesting a role for the antisense RNA in posttranscriptional regulation of FGF-2 expression in this tissue. The FGF-AS is complementary to two widely separated regions in the long 3' untranslated region of the FGF-2 mRNA, in the vicinity of the proximal and distal polyadenylylation sites. These findings demonstrate that the FGF-2 and fgf-as RNAs are coordinately transcribed on a tissue-specific and developmentally regulated basis and suggest that interaction of the sense and antisense RNAs may result in posttranscriptional regulation of FGF-2 in some tissues.

Expression of basic fibroblast growth factor mRNA after transient focal ischemia: comparison with expression of c-fos, c-jun, and hsp 70 mRNA

We have reported that basic fibroblast growth factor (bFGF) prevents retrograde degeneration of thalamic neurons after middle cerebral artery (MCA) occlusion. To identify the protective mechanism of bFGF, we examined bFGF mRNA expression in a model of transient focal ischemia with in situ hybridization. Compared to c-fos, c-jun, and hsp 70 mRNA expression, upregulation of the bFGF mRNA expression was delayed until 6 h after reperfusion. By 12 h, bFGF mRNA was markedly induced in the peri-infarcted cortex, cingulate cortex, and peri-infarcted white matter. At 24 h and 2 days the induction of bFGF mRNA in these regions persisted, and disappeared by 5 day. The quantitative assessment of bFGF mRNA expression revealed that optical density ratios of the cingulate gyrus and the caudoputamen were significantly higher at 12 h, 24 h, and 2 d after reperfusion than those in sham controls. Microscopic observation indicated bFGF mRNA signals were present in several types of cortical cells, including neurons and nonneuronal cells. Since intrinsic bFGF, released from the damaged tissue, can influence the healing response through receptors upregulated by injury, it is reasonable that this pattern of bFGF mRNA expression parallels the bFGFR mRNA expression previously reported.

Biological activity of interleukin-10 in the central nervous system

Cytokines play a crucial role as mediators of inflammation. Astrocytes and microglia are the two major glial cells involved in the central nervous system immune responses. In this study we examined the effects of interleukin-10 (IL-10), one of the naturally occurring inhibitory cytokines, on different types of glial cells in culture such as rat astrocytes, hamster microglia and C6-2B glioma cells. Phosphorylation of signal transducers and activators of transcription (STAT) proteins was used as a marker for IL-10 activity. Within minutes, IL-10 elicited a strong and weak increase in STAT3 and STAT1 phosphorylation, respectively, in human T lymphocytes, suggesting that STAT3 is a main IL-10 signaling event in these cells. In contrast, IL-10 failed to induce STAT3 in glial cells, but elicited a weak increase in STAT1 phosphorylation in microglia and C6-2B glioma cells only, suggesting that in some glial cell population(s) IL-10 may produce cellular responses via activation of the STAT1 pathway. Moreover, in C6-2B cells, IL-10 elicited a decrease in the level of basic fibroblast growth factor mRNA. A similar decrease was observed in adult rat hypothalamus, indicating that this cytokine may regulate glial production of trophic factors. Our data suggest that IL-10 may play a role in glial cell differentiation and proliferation.

Peptide growth factors and the adrenal cortex

Increasing evidence suggests that the actions of classical stimulants of adrenocortical growth and function, such as ACTH or dietary sodium restriction, may partially be mediated via locally produced regulators. Several peptide growth factors, such as basic fibroblast growth factor, insulin-like growth factors, and transforming growth factor-beta 1, have emerged in recent years as multifunctional molecules that typically play such regulatory roles. Adrenocortical cells are highly responsive to these growth factors, in particular in the regulation of cell growth and differentiated functions, such as steroidogenesis. In addition, growth factor expression in the adrenal cortex has been shown to be regulated by physiological stimulants. The spatial expression, release, and activation of these growth factors may, therefore, locally mediate or amplify the actions of the hypothalamo-pituitary axis and the renin-angiotensin system on adrenocortical proliferation, differentiation, and steroidogenesis.

A cDNA encoding fish fibroblast growth factor-2, which lacks alternative translation initiation

Here, we describe the isolation of a rainbow trout cDNA clone that contains the entire fibroblast growth factor-2 (FGF-2; basic FGF) coding region. Interestingly, the rainbow trout cDNA contains a translation stop codon just upstream of the primary initiating methionine codon and so cannot give rise to the longer forms of FGF-2 that are produced in mammals by alternative translation initiation at leucines farther upstream. Transfection of human FGF-2 cDNA into fish cells shows that fish cells can initiate protein synthesis at an upstream leucine CUG codon; surprisingly, however, synthesis is initiated only at the most 5' CUG and not at the two subsequent CUG codons or the methionine AUG codon also used in mammalian cells. Like other FGF-2 proteins, bacterially produced rainbow trout FGF-2 protein binds tightly to heparin-Sepharose and also promotes the proliferation of fibroblast cells. However, the protein differs from all others previously identified at amino acids 121-123, which are part of the proposed highly conserved receptor-binding domain. Comparisons of the efficacies of recombinant wild-type and mutant rainbow trout FGF-2 proteins demonstrate that these three amino acids are critical to the activity of FGF-2.

Expression of FGF-1 and FGF-2 mRNA during lens morphogenesis, differentiation and growth

PURPOSE

There is now considerable evidence that FGF is involved in lens differentiation and growth throughout life. The aim of this study was to determine potential sites of FGF production in and near the lens during morphogenesis, differentiation and growth.

METHODS

The distribution of FGF-1 and FGF-2 mRNAs was analysed in embryonic, weanling and adult rat eyes by in situ hybridization.

RESULTS

During lens morphogenesis, there was distinct expression of FGF-1, but not FGF-2, in the lens placode and retinal disc cells. Subsequently, both forms of FGF showed similar expression patterns. During lens differentiation, distinct expression of FGFs was associated with elongating primary fiber cells. From embryonic day 20 onwards, lenses showed strongest expression of FGF mRNAs in the transitional zone, where epithelial cells differentiate into fibers, with weaker expression in the anterior epithelium. Messenger RNAs for both FGFs were also localised in ocular tissues near the lens and bordering the ocular media, particularly the cornea, ciliary body, iris and neural retina.

CONCLUSIONS

These findings are consistent with the known distribution of FGF protein in the eye and implicate various ocular tissues as potential sources of FGF that may influence lens cells. Furthermore, the fact that lens cells have the potential for synthesizing FGF, together with evidence from previous studies that lens cells express FGF receptors and respond to lens-derived FGF, raises the possibility that some aspects of lens cell behaviour in situ may be influenced by autocrine mechanism(s) of FGF stimulation.

A common RNA structural motif involved in the internal initiation of translation of cellular mRNAs

The 5'-non-translated regions (5'NTR) of human immunoglobulin heavy chain binding protein (BiP), Antennapedia (Antp) ofDrosophilaand human fibroblast growth factor 2 (FGF-2) mRNAs are reported to mediate translation initiation by an internal ribosome binding mechanism. In this study, we investigate predicted features of the higher order structures folded in these 5'NTR sequences. Statistical analyses of RNA folding detected a 92 nt unusual folding region (UFR) from 129 to 220, close to the initiator AUG in the BiP mRNA. Details of the structural analyses show that the UFR forms a Y-type stem-loop structure with an additional stem-loop in the 3'-end resembling the common structure core found in the internal ribosome entry site (IRES) elements of picornavirus. The Y-type structural motif is also conserved among a number of divergent BiP mRNAs. We also find two RNA elements in the 5'-leader sequence of human FGF-2. The first RNA element (96 nt) is 2 nt upstream of the first CUG start codon located in the reported IRES element of human FGF-2. The second (107 nt) is immediately upstream of the authentic initiator AUG of the main open reading frame. Intriguingly, the folded RNA structural motif in the two RNA elements is conserved in other members of FGF family and shares the same structural features as that found in the 5'NTR of divergent BiP mRNAs. We suggest that the common RNA structural motif conserved in the diverse BiP and FGF-2 mRNAs has a general function in the internal ribosome binding mechanism of cellular mRNAs.

Heparan sulfate potentiates the autocrine action of basic fibroblast growth factor in astrocytes: an in vivo and in vitro study

Increasing evidence indicates that heparan sulfate proteoglycans have a critical role in the regulation of the activity of basic fibroblast growth factor by interacting with it or its receptor. In this study we examined the possibility that heparan sulfate can modulate the basic fibroblast growth factor system at a more fundamental level than activity regulation, by influencing the synthesis of basic fibroblast growth factor and its receptor messenger RNAs. Previous studies in vitro indicate that basic fibroblast growth factor promotes proliferation and differentiation of astrocytes. Accordingly, we examined the possibility that the action of heparan sulfate on the basic fibroblast growth factor system could have a critical role in the modulation of reactivity and/or proliferation of astrocytes in vitro and in vivo. We report that basic fibroblast growth factor applied to pure astrocyte cultures or rat neocortex promoted an increase in the messenger RNA for basic fibroblast growth factor itself and for its receptor. Furthermore, basic fibroblast growth factor applied directly into the brain elicited an increase in messenger RNA for the astrocytic marker glial fibrillary acidic protein. All of these actions, both in vitro and in vivo, were highly potentiated when heparan sulfate was applied in combination with basic fibroblast growth factor. These results suggest that basic fibroblast growth factor regulates astrocytic proliferation or reactivity via an autocrine cascade that involves induction of its own receptor and that this action is modulated by heparan sulfate.

Mutants of basic fibroblast growth factor identify different cellular response programs

Mutations, expected to affect the intracellular routing, i.e. additional nuclear localization sequences (NLS; the natural 23 kDa isoform and a 17D27R mutant) and/or a deletion of amino acids 26-29 (23 delta 26-29 and 17 delta 26-29), were introduced in basic fibroblast growth factor (bFGF). The mutants were assayed for their mitotic activity and their capacity to induce a tissue-specific response in human umbilical vein endothelial cells [HUVECs; induction of urokinase plasminogen activator receptor (u-PAR)], or in rat lens epithelial cells (fibre cell differentiation). In HUVECs, the 17D27R mutant had wild type activity, the 23 kDa and the delta 26-29 proteins were impaired in the induction of both mitosis and u-PAR. The delta 26-29 proteins, but not the 23 kDa protein or 17D27R mutant, were also impaired in receptor binding in that they bound only to a subset of receptors. The concentration of 17 kDa bFGF required for half maximal u-PAR response was 30 fold higher than for the half maximal 3H-thymidine incorporation. Addition of an NLS to bFGF strongly inhibited the induction of fibre cell differentiation, though it had little effect on the stimulation of DNA synthesis. The 17 delta 26-29 kDa mutant had wild type differentiation activity but was a poor mitogen for lens epithelial cells.

Application of an optimised reverse transcriptase-polymerase chain reaction method to determine the cDNA nucleotide sequence of porcine basic fibroblast growth factor

In the present investigation, oligonucleotide primers of high hybridisation stringency have been used in combination with optimised reverse transcriptase-polymerase chain reaction (RT-PCR) methods for the determination of the cDNA sequence corresponding to porcine FGF-2 mRNA present in brain and uterine tissue. Application of these optimised methods have overcome previous limitations associated with the low abundance of the porcine FGF-2 mRNA, and allowed as little as 100 micrograms of tissue to be employed to generate the complete cDNA nucleotide sequences as well as to provide specific template fragments selected for their suitability in subsequent ligation and mutagenesis studies with conventional expression vectors. Comparisons of the cDNA nucleotide and the deduced amino-acid sequence of porcine FGF-2 and the known FGF-2s from other species have indicated nucleotide sequence homologies of 95.5% with the bovine, 94.7% with the human and 88.7% with the rat FGF-2 cDNA whilst amino-acid sequence homologies of 100% with the bovine, 98.7% with the human and 96.8% with the rat FGF-2, respectively, were found. Based on these investigations, application of analogous strategies and methods with low abundance mRNAs related to other members of this family of growth factors, as well as very low abundance mRNAs of other protein growth factor, in the pig should now be readily realised.

Alpha 2-adrenergic agonists induce basic fibroblast growth factor expression in photoreceptors in vivo and ameliorate light damage

We observed an induction of basic fibroblast growth factor (bFGF) mRNA in the rat retina after systemic administration of the alpha 2-adrenergic agonists xylazine and clonidine. A single injection of xylazine or clonidine transiently increased bFGF mRNA. Preinjection of yohimbine, an alpha 2-adrenergic antagonist, completely inhibited this increase. Higher dosage of yohimbine inhibited the baseline expression of bFGF. Of particular interest is the finding that the induced bFGF expression occurred almost exclusively in the inner segment region of photoreceptors. No increase in bFGF mRNA was found in the brain after either xylazine or clonidine injection. Xylazine or clonidine given systemically before and during constant light exposure also reduces photoreceptor degeneration in albino rats. These results indicate that regulation of bFGF expression in photoreceptors is unique in the CNS and suggest that endogenous bFGF promotes photoreceptor survival.

Regulation of connexin-43, GFAP, and FGF-2 is not accompanied by changes in astroglial coupling in MPTP-lesioned, FGF-2-treated parkinsonian mice

Basic fibroblast growth factor (bFGF; FGF-2) has potent trophic effects on developing and toxically impaired midbrain dopaminergic (DAergic) neurons which are crucially affected in Parkinson's disease. The trophic effects of FGF-2 are largely indirect, both in vitro and in vivo, and possibly involve intermediate actions of astrocytes and other glial cells. To further investigate the cellular and molecular mechanisms underlying the restorative actions of FGF-2, and to analyse in more detail the changes within astroglial cells in the MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-lesioned striatum, we have studied striatal expression and regulation of connexin-43 (cx43), the principal gap junction protein of astroglial cells, along with the expression of glial fibrillary acidic protein (GFAP), FGF-2, and functional coupling. Our results show an immediate, yet transient increase in cx43 mRNA, and a sustained increase in FGF-2 mRNA, GFAP-positive cells, and cx43-immunoreactive punctata following the MPTP lesion, without any induction of functional coupling between astrocytes and other glial cells as revealed by dye coupling of patched cells. Unilateral administration of FGF-2 in a piece of gelfoam caused a further increase in cx43-positive punctata immediately adjacent to the implant, which was more pronounced than after application of a gelfoam containing the nontrophic control protein cytochrome C. These changes were parallelled by a small increase in cx43 protein determined by Western blot, but not by alterations in the coupling state of cells in the vicinity of the gelfoam implant. Although our data indicate that MPTP and exogenous FGF-2 may alter expression and protein levels of cx43, they do not support the notion that increases in cellular coupling may underly the trophic and widespread actions of FGF-2 in the MPTP-model of Parkinson's disease.

Increased expression of basic fibroblast growth factor (bFGF) following focal cerebral infarction in the rat

Basic fibroblast growth factor (bFGF) is a polypeptide with potent trophic effects on brain neurons, glia, and endothelial cells. In the current study, we used Northern blotting, in situ hybridization, and immunohistochemical techniques to examine bFGF expression in brain following focal infarction due to permanent occlusion of the proximal middle cerebral artery in mature Sprague-Dawley rats. We found a four-fold increase in bFGF mRNA in tissue surrounding focal infarcts at 1 day after ischemia. In situ hybridization showed that this increase was found throughout several structures in the ipsilateral hemisphere, including frontoparietal, temporal, and cingulate cortex, as well as in caudoputamen, globus pallidus, septal nuclei, nucleus accumbens, and olfactory tubercle. Increased bFGF mRNA expression was associated with cells having the distinct morphological appearance of astroglia in these structures. Immunohistochemistry showed an increase in the size and number of bFGF-immunoreactive (IR) nuclei in these same structures, as well as a shift from nuclear to nuclear plus cytoplasmic localization of immunoreactivity, beginning at 1 day, and peaking at 3 days after ischemia. Double immunostaining identified bFGF-IR cells as astroglia in these structures. (An exception was the piriform cortex, in which both increased bFGF mRNA levels and increased bFGF-IR was found in neurons at 1 day after ischemia). Overall, the peak of increased bFGF expression preceded the peak in expression of the astroglial marker GFAP within the ipsilateral hemisphere. Increased bFGF expression may play an important role in the glial, neuronal, and vascular changes occurring after focal infarction.

Analysis of basic fibroblast growth factor in rats with inherited retinal degeneration

In RCS rats, photoreceptors degenerate between postnatal days 20 and 60, secondary to a genetic defect expressed in the neonatal retinal pigmented epithelium (RPE). Previous work has shown delay of the photoreceptor degeneration in this model by intraocular injection of basic fibroblast growth factor (bFGF). Evidence is presented here, from bFGF immunostaining and Northern analysis of bFGF mRNA, for reduced bFGF expression in uncultured RPE of dystrophic RCS pups. It is also shown that in the mutant eyes angiogenesis in the underlying choroid, which normally occurs between postnatal days 7 and 10, is markedly delayed, with irregular distribution of vessels, consistent with a reduction in this known angiogenesis factor. Mutational analysis of the bFGF transcript and gene by denaturing gradient gel electrophoresis and Southern analysis did not, however, reveal abnormalities in the coding sequence of this gene in RCS rats.

Antisense inhibition of basic fibroblast growth factor induces apoptosis in vascular smooth muscle cells

Basic fibroblast growth factor (bFGF), a potent mitogen for many cell types, is expressed by vascular smooth muscle cells and plays a prominent role in the proliferative response to vascular injury. Basic FGF has also been implicated as a survival factor for a variety of quiescent or terminally differentiated cells. Autocrine mechanisms could potentially mediate both proliferation and cell survival. To probe such autocrine pathways, endogenous bFGF production was inhibited in cultured rat vascular smooth muscle cells by the expression of antisense bFGF RNA. Inhibition of endogenous bFGF production induced apoptosis in these cells independent of proliferation, and apoptosis could be prevented by exogenous bFGF but not serum or epidermal growth factor. The induction of apoptosis was associated with an inappropriate entry into S phase. These data demonstrate that interruption of autocrine bFGF signaling results in apoptosis of vascular smooth muscle cells, and that the mechanism involves disruption of normal cell cycle regulation.

Expression of the rat BFGF antisense RNA transcript is tissue-specific and developmentally regulated

The basic fibroblast growth factor (bFGF) gene locus is transcribed into a number of mRNA transcripts including an antisense mRNA derived from the opposite DNA strand of the bFGF gene. Expression of this natural antisense RNA has been implicated in regulation of the bFGF sense mRNA expression and turnover. In the present study we examined the developmental pattern of expression of the bFGF antisense transcript in fetal and postnatal rat tissues. Northern hybridization with a strand-specific cRNA probe detected a 1.5-kb polyadenylated antisense RNA in all tissues examined except brain, in which two transcripts were detected as a doublet of approximately 1.3-1.5 kb in size. The level of antisense transcript expression was markedly tissue- and age-dependent. In the developing brain, both sense and antisense transcripts were detected by Northern hybridization, but the pattern of their expression was inversely related. The 6.0-kb bFGF sense transcript increased in an age-dependent manner from days 3-30 of postnatal development while the antisense transcript decreased to nearly undetectable levels over the same period. In embryonic (days 15-19) liver, kidney, heart and intestine bFGF antisense RNA expression was low but increased dramatically at parturition, rising 5-10-fold over fetal levels by 10 days of age, then declined slowly to a new steady-state level in adult tissues. The level of antisense RNA in these tissues was much higher than that of bFGF sense mRNA, which was undetectable by Northern analysis. Sense and antisense trancripts were also detected in midgestational (11.5 days) embryos by RT-PCR. Antisense expression did not increase when embryos were explanted and cultured for 48 h (9.5-11.5 days). The apparent reciprocal relationship between the abundance of sense and antisense bFGF transcripts in developing brain supports the possibility of a regulatory role for the antisense transcript in this tissue. There was no evidence for a reciprocal relationship between sense and antisense expression in the other tissues examined, indicating that the relationship between sense and antisense RNA expression may be tissue-specific.

Enhanced gene expression of transforming growth factor-alpha and c-met in rat urinary bladder cancer

To investigate the roles of growth factors in bladder cancer, changes in the expression of messenger RNAs (mRNAs) for several growth factors and their receptors were examined during rat bladder carcinogenesis induced with N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN). Northern blot analysis showed that the contents of mRNAs for transforming growth factor-alpha (TGF-alpha) and c-met/hepatocyte growth factor (HGF) receptor increased with BBN treatment. Epidermal growth factor (EGF) receptor mRNA was hardly affected by the treatment; while mRNA for fibroblast growth factor (FGF) receptor 1 and transforming growth factor-beta (TGF-beta) type II receptor decreased with BBN treatment. A rat bladder tumor cell line, NBT-II, expressed both TGF-alpha and c-met mRNAs, and HGF showed apparent scattering and growth-stimulating effects on the cells. These results indicate the possibility that TGF-alpha produced by a bladder cancer, in addition to urinary EGF, plays a role in the development of bladder cancer, and that enhanced cell motility due to activation of the c-met/HGF receptor participates in the invasion and metastasis of the cancer cells.

High and low molecular weight fibroblast growth factor-2 increase proliferation of neonatal rat cardiac myocytes but have differential effects on binucleation and nuclear morphology. Evidence for both paracrine and intracrine actions of fibroblast growth factor-2

Basic fibroblast growth factor (FGF-2) plays a vital role in the growth and differentiation of cardiac myocytes. It exists in high and low molecular weight forms because of the use of alternative initiation codons in the same mRNA. Higher levels of high molecular weight forms (molecular mass of 22 and 21.5 kD) are present in the rat heart during the neonatal stage, whereas the low molecular weight form (molecular mass of 18 kD) is predominant in the adult heart, suggesting different roles in development. Rat FGF-2 cDNAs that can preferentially express high or low molecular weight forms were introduced into neonatal rat ventricular myocyte cultures. Significant and comparable increases in overall cardiac myocyte DNA synthesis and proliferation were seen with 22/21.5- and 18-kD FGF-2 expression. A significantly higher mitotic index was seen in the vicinity of cardiac myocytes overexpressing high or low molecular weight forms of FGF-2 compared with nonoverexpressing cells. This increase was inhibited in the presence of neutralizing antibodies to FGF-2, pointing to a proximity-dependent paracrine effect of 22/21.5- and 18-kD FGF-2 on mitosis. By contrast, overexpression of high but not low molecular weight FGF-2 was associated with a significant increase in binucleation (approximately 36% of cardiac myocytes overexpressing 22/21.5-kD FGF-2 were binucleated compared with 9% of cardiac myocytes overexpressing 18-kD FGF-2), which was not affected by neutralizing antibodies to FGF-2. These results suggest that 22/21.5-kD FGF-2 and 18-kD FGF-2 have similar paracrine effects on proliferation but that 22-21.5-kD FGF-2 exerts a distinct intracrine effect on binucleation.

Chronic continuous infusion of (-)nicotine reduces basic fibroblast growth factor messenger RNA levels in the ventral midbrain of the intact but not of the 6-hydroxydopamine-lesioned rat

A negative correlation has been found between smoking and Parkinson's disease. There is evidence to suggest that this correlation appears to be associated with a neuroprotective role of nicotine for dopamine neurons at least in relation to mechanical injury. However, 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP) neurotoxicity to dopamine neurons is enhanced by chronic continuous (-)nicotine. More recently, basic fibroblast growth factor has been found to possess neurotrophic activities for many nerve cells including the dopamine cells in vivo and in vitro. Therefore, it is of interest to explore a possible effect of nicotine on basic fibroblast growth factor expression in the ventral midbrain of intact and 6-hydroxydopamine-lesioned rats and how treatment with nicotine can alter the 6-hydroxydopamine-induced injury of the nigral dopamine nerve cells as evaluated by dopamine biochemistry. In the present paper, an analysis of the effects of chronic continuous infusion of (-)nicotine via minipumps was carried out on basic fibroblast growth factor expression in the vental midbrain of the intact male rat and of the 6-hydroxydopamine lesioned rat. A quantitative messenger RNA protection assay analysis was used as well as an immunocytochemical analysis in the substantia nigra. Our findings give evidence that a two-week continuous infusion with (-)nicotine in the intact rat leads to substantial and dose-related (0.03-0.3 mg/kg per h) reductions of basic fibroblast growth factor messenger RNA levels in the ventral midbrain. These changes are not associated with changes in neuronal and glial basic fibroblast growth factor immunoreactivity in this region with the antibodies used. However, a one-week continuous infusion with (-)nicotine (0.125 mg/kg per h) failed to significantly alter the basic fibroblast growth factor messenger RNA levels in the ventral midbrain of solvent and 6-hydroxydopamine-injected rats and thus also the 6-hydroxydopamine-induced increase of basic fibroblast growth factor messenger RNA levels in the ventral midbrain of the lesioned side observed at this time-interval and known to be of astroglial origin [Chadi G. et al. (1994) Neuroscience 61, 891-910]. In agreement, the 6-hydroxydopamine-induced depletion of dopamine in the neostriatum was unaltered by the nicotine treatment (0.125 mg/kg per h). Thus, chronic continuous (-)nicotine treatment may lead to a reduced basic fibroblast growth factor trophic tone in the ventral midbrain of the intact but not of the 6-hydroxydopamine-lesioned rat neither on the lesioned nor on the unlesioned side of the ventral midbrain. It seems possible that chronic nicotine treatment mainly reduces basic fibroblast growth factor messenger RNA levels of neuronal origin, since the astroglial messenger RNA levels dominate after the 6-hydroxydopamine-induced lesions.

Correlation between increased AP-1NGF binding activity and induction of nerve growth factor transcription by multiple signal transduction pathways in C6-2B glioma cells

Transcription mechanisms regulating nerve growth factor (NGF) gene expression in the CNS are yet to be thoroughly understood. We have used C6-2B rat glioma cells to characterize the signal transduction pathways that contribute to transcriptional and posttranscriptional regulation of NGF mRNA. Because the NGF promoter contains an AP-1 consensus sequence, we have investigated whether increases in AP-1 binding activity correlate with enhanced NGF mRNA expression. Gel mobility shift assays using an oligonucleotide homologous to the AP-1 responsive element of the rat NGF gene (AP-1NGF) revealed that 12-O-tetradecanoyl phorbol-13-acetate (TPA) and, to a lesser extent, isoproterenol (ISO) and thapsigargin, a microsomal Ca(2+)-ATPase inhibitor, stimulated binding to AP-1NGF within 2 h. All of these stimuli increased NGF mRNA levels within 3 h. Cycloheximide pretreatment blocked the TPA and ISO-mediated binding to AP-1NGF suggesting that de novo synthesis of c-Fos/c-Jun may be required for the transcriptional regulation of NGF gene. Nuclear run-on assays and NGF mRNA decay studies revealed that TPA increases NGF transcription whereas ISO affects both transcription and mRNA stabilization. We propose that (i) different signal transduction mechanisms regulate the expression of the NGF gene in cells derived from the CNS, and (ii) both mRNA transcription and stability account for the cAMP-mediated increase in NGF mRNA levels.

Immunohistochemical localization of basic fibroblast growth factor in bovine ovarian follicles

Basic fibroblast growth factor (bFGF, FGF2) controls cell proliferation and differentiation in many organs and tissues. In the ovary, cells proliferate and differentiate during folliculogenesis and during formation of the corpus luteum. While previous studies have inferred a role for bFGF in these processes, the precise contribution of bFGF to follicular activation or recruitment has not been established. For this reason, bFGF was immunolocalized in bovine follicles, using anti-bFGF immunoglobulin specific for the 1-24-amino acid terminus of the 18-kDa peptide. Basic FGF was immunolocalized to the cytoplasm of oocytes from bovine primordial and primary follicles. Strong immunostaining was also observed in corpora lutea, the ovarian surface epithelium, and smooth muscle cells surrounding blood vessels, while substantial levels of immunostaining were also present in cells of the theca interna. In most of the healthy antral follicles examined, the three or so layers of granulosa cells which were closest to the basement membrane were also stained, with greatest levels of staining at the most basal region of each cell. Atretic antral follicles had significant and uniform levels of immunostaining throughout the theca interna and the membrana granulosa. Immunostaining as described above was reduced to background levels when the primary specific immunoglobulin was preabsorbed with a 350 molar excess of peptide comprising the NH2-terminal 24 amino acids of bFGF. Based upon our previous observations and those reported here, we propose that basic fibroblast growth factor is synthesized by immature oocytes, especially those from primordial and primary follicles, and that bFGF has a potential role in activating follicle growth via stimulation of granulosa cell proliferation and follicular basement membrane synthesis.

Adrenalectomy reduces FGF-1 and FGF-2 gene expression in specific rat brain regions and differently affects their induction by seizures

We have previously reported that limbic seizures regulate the gene expression of fibroblast growth factor-2 (basic, FGF-2) according to a specific spatio-temporal pattern. In the present paper we have investigated the role of adrenal hormones on seizure-induced elevation of fibroblast growth factor-1 (acidic, FGF-1) and FGF-2 gene expression. Adrenalectomy reduces FGF-2 mRNA expression in specific brain regions, such as frontal cortex, hippocampus and striatum, whereas FGF-1 mRNA levels were decreased only in the frontal cortex. The injection of kainic acid in adrenalectomized rats produced a widespread increase of FGF-2 mRNA with a pattern similar to sham animals as indicated by in situ hybridization. In contrast, although kainate-induced elevation of FGF-1 mRNA in the hippocampus was not influenced by adrenalectomy, its induction in frontal cortex was prevented by this surgery procedure. Taken together, these data indicate that adrenal hormones play a role in the regulation of the gene expression for fibroblast growth factors, but different mechanisms are operative in their induction following seizure activity.

A long-term receptor stimulation is requisite for angiotensin II-dependent DNA synthesis in vascular smooth muscle cells from spontaneously hypertensive rats

Angiotensin II stimulates DNA synthesis in aortic smooth muscle cells prepared from spontaneously hypertensive rats, with maximal levels detected 20 h after stimulation. Angiotensin II receptor antagonists inhibited the angiotensin II-induced DNA synthesis. In particular, the noncompetitive antagonist 2-ethoxy-1-[[2'(1 H-tetrazol-5-yl) biphenyl-4-yl]methyl]-1 H-benzimidazole-7-carboxylic acid (CV11974) was more effective than expected from its affinity for the angiotensin II receptor and its potency for inhibiting angiotensin II-induced increase in cytosolic free Ca2+ concentration 2-n-Butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1 H-tetrazol-5-yl)biphenyl-4-yl) methyl]imidazole, potassium salt (losartan), one of the antagonists, inhibited angiotensin II-induced DNA synthesis by 92% and 79%, even when added 2 and 4 h after angiotensin II stimulation, respectively. Angiotensin II also increases the mRNA of platelet-derived growth factor-A chain and basic fibroblast growth factor. The increase was observed within 4 h after angiotensin II stimulation. In this case, the addition of losartan at 4 h after angiotensin II stimulation hardly influenced the time course of the mRNA level of growth factors. Also, conditioned media of cells stimulated with angiotensin II did not influence DNA synthesis in the presence of CV11974. These results suggest that sustained receptor stimulation with angiotensin II is required for DNA synthesis in addition to the early intracellular signaling following phospholipase C activation in a manner independent of the induction of growth factors such as platelet-derived growth factor-AA and basic fibroblast growth factor.

Intracellular signaling pathways required for rat vascular smooth muscle cell migration. Interactions between basic fibroblast growth factor and platelet-derived growth factor

Intracellular signaling pathways activated by both PDGF and basic fibroblast growth factor (bFGF) have been implicated in the migration of vascular smooth muscle cells (VSMC), a key step in the pathogenesis of many vascular diseases. We demonstrate here that, while bFGF is a weak chemoattractant for VSMCs, it is required for the PDGF-directed migration of VSMCs and the activation of calcium/calmodulin-dependent protein kinase II (CamKinase II), an intracellular event that we have previously shown to be important in the regulation of VSMC migration. Neutralizing antibodies to bFGF caused a dramatic reduction in the size of the intracellular calcium transient normally seen after PDGF stimulation and inhibited both PDGF-directed VSMC migration and CamKinase II activation. Partially restoring the calcium transient with ionomycin restored migration and CamKinase II activation as did the forced expression of a mutant CamKinase II that had been "locked" in the active state by site-directed mutagenesis. These results suggest that bFGF links PDGF receptor stimulation to changes in intracellular calcium and CamKinase II activation, reinforcing the central role played by CamKinase II in regulating VSMC migration.

Chronic ethanol administration decreases brain-derived neurotrophic factor gene expression in the rat hippocampus

We have previously demonstrated that chronic ethanol consumption decreases neurotrophic activity in hippocampal extracts, as assessed by a chick dorsal root ganglia bioassay, but has no effect on hippocampal NGF mRNA or NGF protein levels. We presently report that hippocampal mRNAs encoding neurotrophin-3 and basic fibroblast growth factor are also unaffected. However, in contrast, brain-derived neurotrophic factor mRNA is reliably decreased, thereby suggesting that ethanol-induced damage of the septohippocampal system may at least partially result from an ethanol-induced decrease in hippocampal brain-derived neurotrophic factor expression.

Transforming growth factor-beta 1 and fibroblast growth factors in rat growth plate

Chondrocytes in the growth plate progress in an orderly fashion from resting through proliferating to hypertrophic cells. In the region of hypertrophic chondrocytes, the cartilage is invaded by capillary loops and endochondral ossification is initiated. It is currently believed that growth factors may regulate the proliferation and maturation of chondrocytes and the synthesis of extracellular matrix in the growth plate. The ordered sequence of proliferation and differentiation observed in the growth plate provides a unique opportunity to study the role of acidic fibroblast growth factor, basic fibroblast growth factor, and transforming growth factor-beta 1 in the regulation of these processes. In this study, expression of the mRNA of these growth factors was examined using total RNA extracted from the physis and epiphysis of rat tibias. Transforming growth factor-beta 1 mRNA was detected by Northern hybridization. Expression of the genes encoding acidic and basic fibroblast growth factors was demonstrated by polymerase chain reaction amplification. In addition, using polyclonal antibodies against these growth factors, we localized them by immunohistochemical analysis. Strong intracellular staining with a predominantly nuclear pattern was observed in chondrocytes from the proliferating and upper hypertrophic zones. In contrast, chondrocytes in the resting zone stained only faintly for the presence of these growth factors. Some chondrocytes in the resting zone adjacent to the proliferating zone stained with these antibodies, and the antibodies also stained cells in the zone of Ranvier, which regulates latitudinal bone growth. Lastly, the location of transforming growth factor-beta 1 was examined further with use of a polyclonal antipeptide antibody specific for its extracellular epitope.(ABSTRACT TRUNCATED AT 250 WORDS)

Single step purification of biologically active recombinant rat basic fibroblast growth factor by immobilized metal affinity chromatography

The construction and use of a plasmid which allows the expression and single step purification of recombinant rat basic fibroblast growth factor (bFGF) is described. A cDNA encoding rat bFGF was subcloned into the expression plasmid pQE-9 (Qiagen) in such a way that the bFGF which is produced from the resulting construct contains 6 histidine residues near the amino terminus. The resulting plasmid, pQE-9-bFGF, was expressed in the E. coli strain M15[pREP4] and the 6 x His-bFGF was purified to homogeneity from the soluble fraction of the bacterial cell lysate in a single step by affinity chromatography on a nickel chelate resin. About 5 mg of 6 x His-bFGF was obtained from the soluble fraction from one liter of bacterial cell culture. Testing of the 6 x His-bFGF in a PC12 cell differentiation assay showed that its activity was comparable to the activities for native bFGF and recombinant bFGF purified by multistep methods.

Factors involved in capillary growth in the heart

Growth of capillaries in the heart occurs under physiological circumstances during endurance exercise training, exposure to high altitude and/or cold, and changes in cardiac metabolism or heart rate elicited by modification of thyroid hormone levels. Capillary growth in all these conditions can be linked with increased coronary blood flow, decreased heart rate, or both. This paper brings evidence that, although increased blood flow due to long-term administration of coronary vasodilators results in capillary growth, a long-term decrease in heart rate induced by electrical bradycardial pacing in rabbits and pigs, or by chronic administration of a bradycardic drug, alinidine, in rats, stimulates capillary growth with little or no change in coronary blood flow. Decreased heart rate results in increased capillary wall tension, increased end-diastolic volume and increased force of contraction, and thus stretch of the capillary wall. This could lead to release of various growth factors possibly stored in the capillary basement membrane. Correlation was found between capillary density (CD) and the levels of low molecular endothelial cell stimulating angiogenic factor (ESAF) both in rabbit and pig hearts with CD increased by pacing. There was no relation between expression of mRNA for basic fibroblast growth factor and CD in sham-operated and paced rabbit hearts. In contrast, mRNA for TGF beta was increased in paced hearts, and the possible role of this factor in the regulation of capillary growth induced by bradycardia is discussed.

Expression of acidic FGF mRNA in rat auditory brainstem during postnatal maturation

In situ hybridization was used to investigate the mRNA distribution of acidic and basic fibroblast growth factor (aFGF and bFGF) in the auditory brainstem of neonatal and adult rats. bFGF mRNA was not detected at any age. In adult rats, aFGF mRNA was strongly expressed in the principal neurons of the anteroventral and posteroventral cochlear nuclei, but not in the octopus cells. In the dorsal cochlear nucleus, aFGF mRNA was seen only in scattered smaller vertical cells. aFGF was strongly expressed in the nucleus of the trapezoid body and in all periolivary cell groups, but not in the medial and lateral olivary nuclei. No expression was observed in the lemniscal nuclei or in the central nucleus of the inferior colliculus, but large neurons in the external zone of the colliculus were labeled. Developmentally, low levels of aFGF expression appeared in the cochlear nuclei and olivary nuclei between P0 and P6. This expression increased rapidly during the onset of hearing, between P10 and P14, and reached adult level by P14-P17. Labeling in collicular neurons appeared slightly later. The results suggest that the appearance of strong aFGF mRNA expression is related to the onset of function.

The role of angiogenesis in the tumor growth of Syrian hamster pancreatic cancer cell line HPD-NR

BACKGROUND/AIMS

New therapeutic approach is required for pancreatic cancer, one of the most intractable malignancies. The role of angiogenesis in the tumor growth of a Syrian hamster pancreatic cancer cell line HPD-NR, which closely resembles its human counterpart, was investigated.

METHODS

Angiogenic activity was measured as stimulation of growth of human umbilical vein endothelial cells (HUVEC), and angiogenic factors produced by HPD-NR cells were identified by reverse-transcription polymerase chain reaction and Northern blot analysis. Then in vitro and in vivo antitumor effects of a potent angiogenesis inhibitor, O-(chloroacetylcarbamoyl)fumagillol (AGM-1470), were examined.

RESULTS

The conditioned medium of HPD-NR cells stimulated the growth of HUVEC, and four hamster angiogenic factors were detected with an overexpression of transforming growth factor alpha and vascular endothelial growth factor messenger RNAs. AGM-1470 specifically inhibited the growth of HUVEC and that of HPD-NR tumors in vivo with decreased vascularity of the tumors but not the growth of HPD-NR cells in vitro.

CONCLUSIONS

The results suggest that angiogenesis plays an important role in tumor growth of HPD-NR cells and can be a new target of medical therapy for pancreatic cancer.

Heterogeneity of human neuroblastoma cell lines in their proliferative responses to basic FGF, NGF, and EGF: correlation with expression of growth factors and growth factor receptors

Growth factors can induce both proliferation or differentiation of neuroblastoma (NB) cells through interaction with specific receptors. Using two automated colorimetric assays for determinations of cell numbers, the present study demonstrates that a) different NB and neuroepithelioma cell lines show distinct responses, both qualitatively and quantitatively, to basic FGF (bFGF), NGF, and EGF; b) even closely related NB cell lines (e.g., SK-N-SH, SH-SY5Y, and SHEP) do not respond uniformly to these factors; c) responses of the two neuroepithelioma cell lines employed (SK-N-MC and CHP-100) differ, but match those of certain NB cell lines; and d) two growth factors, bFGF and EGF, may both stimulate or inhibit proliferation, depending on the cell line studied. Specifically, IMR-32, SK-N-SH, and SH-SY5Y showed a mitogenic response to each growth factor. Maximal proliferative responses ranged from 204-355% as compared to controls (100%). GICAN was stimulated by NGF (199%), and SK-N-MC and NMB by EGF (282 and 140%, respectively), but other factors were ineffective. CHP-100 and GIMEN were inhibited by bFGF. NGF and EGF were not effective on CHP-100 cells, while EGF caused an arrest of mitogenic activity in GIMEN cells, and NGF stimulated their proliferation. Cell lines SHEP and LAN1 did not respond to any factor. To begin to analyze putative relationships of growth factor responsiveness and growth factor/growth factor receptor expressions, IMR-32, GIMEN, and LAN1 cell lines were studied for the presence of bFGF, NGF, FGF receptors (R)-1 (flg) and FGFR-4, trk, and low-affinity NGF receptor (p75) mRNAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of nerve growth factor and basic fibroblast growth factor mRNA following clenbuterol: contrasting anatomical and cellular localization

RNase protection assay and in situ hybridization were used to analyze the temporal and cellular changes in nerve growth factor (NGF) and basic fibroblast growth factor (bFGF) mRNA content evoked by the lipophilic beta-adrenergic receptor agonist clenbuterol in adult rat brain. Clenbuterol elicited a threefold increase in NGF mRNA expression which was limited to the cerebral cortex. This increase was maximal at 5 h, still evident by 10 h, and declined to control levels by 24 h. By 10 h NGF protein was also increased. Elevated NGF mRNA hybridization following clenbuterol was localized in the superficial cortical layers II and III in large Nissl-pale cells, suggesting that NGF mRNA induction occurs in neurons. In the same animals, clenbuterol induced a twofold increase in the levels of bFGF mRNA in cerebral cortex and hippocampus. This increase was localized primarily in glial cells as demonstrated by bFGF mRNA hybridization over all cortical regions and by labeling of the stratum lacunosum moleculare of the hippocampus. Our results suggest that enhanced noradrenergic tone regulates expression of these two trophic factors by different synaptic mechanisms and suggest that neurotransmitter(s) can coordinate trophic influences on different cell populations.

Cellular events in the evolution of experimental diabetic nephropathy

In several models of progressive glomerular disease, mesangial cell proliferation, phenotypic change and increased growth factor expression precede up-regulation of genes for extracellular matrix components (ECM) and mesangial expansion. To examine these events in diabetic nephropathy (DN) we conducted sequential studies of glomeruli in rats with streptozotocin induced DN. We found prominent mesangial cell proliferation at three days (4.34 +/- 2.24 PCNA + cells/glom vs. 1.6 +/- 0.74 in controls, P < 0.001) associated with increased alpha-actin expression. PDGF B-chain mRNA was slightly increased at day one, and PDGF B-chain immunostaining was slightly increased at days one and six. Staining for bFGF was significantly increased at three days (2.2 +/- 0.6 vs. 1.2 +/- 0.1 in controls, P < 0.01). There was also an early increase in platelets in glomeruli of diabetic animals, and platelet depletion significantly inhibited the early phase of proliferation. In addition to mesangial cell proliferation, a prominent glomerular macrophage infiltration began at day three and peaked at day 30 (3.94 +/- 1.47 vs. 2.08 +/- 1.13 in controls, P < 0.01). TGF-beta mRNA increased at days 14 and 30. Insulin treatment prevented mesangial cell proliferation, actin expression, and macrophage infiltration, and normalized TGF-beta expression at 14 and 30 days. These multiple cellular events preceded any detectable increases in glomerular gene expression or deposition of collagen I, IV or laminin.

Expression of FGF-2 and FGF receptor type 1 in the adult rat brainstem: effect of colchicine

In the adult rat brainstem, neuronal subpopulations of several motor and sensory nuclei display basic fibroblast growth factor (bFGF or FGF-2) immunoreactivity (IR; Grothe et al. J. Comp. Neurol. 305:328-336). In the present study we demonstrate that FGF-2-IR correlates with staining for the high-affinity FGF-receptor 1. Intracerebroventricular injection of colchicine leads to the disappearance or substantial reduction of FGF-2-IR in the hypoglossal, facial, trigeminal motor, trochlear, and mesencephalic trigeminal nuclei. In contrast, FGF-2-IR appears in many perikarya of the red nucleus and the medial nucleus of the trapezoid body, whereas in control rats both nuclei showed immunostained fibers and almost no immunoreactive cell bodies. This dramatic change of FGF-2-IR could be explained by the ability of colchicine to block fast axonal transport. Cranial nuclei may internalize FGF-2 at the periphery via high-affinity receptors and retrogradely transport the molecule to their perikarya. The red nucleus and the medial nucleus of the trapezoid body may synthesize FGF-2 and provide the growth factor to afferent or efferent neurons. The presence of FGF-2 mRNA in brainstem extract and the absence of the FGF-2 transcript in extracts of the hypoglossal nucleus corroborate this suggestion. The effect of colchicine on FGF-2-IR in the brainstem nuclei suggests that FGF-2 could be specifically retrogradely transported in other cranial nuclei, in addition to the hypoglossal system. Together with the ability of FGF-2 to stimulate neuronal survival, this result strongly supports the hypothesis that FGF-2 is acting as a neurotrophic factor on specific central neuron populations.

Insulin-like growth factor-1 mRNA is increased in deafferented hippocampus: spatiotemporal correspondence of a trophic event with axon sprouting

Deafferentation is known to induce axonal sprouting in adult brain, but the signals that direct this response are not understood. To evaluate the possible roles of insulin-like growth factor-1 (IGF-1) and basic fibroblast growth factor (bFGF) in central axonal sprouting, the present study used in situ hybridization to evaluate IGF-1 and bFGF mRNA expression in entorhinal deafferented rat hippocampus. Alternate tissue sections were processed for Fink-Heimer impregnation of axonal degeneration, Bandeiraea simplicifolia (BS-1) labeling of microglia, and glial fibrillary acidic protein immunocytochemistry. In control hippocampus, IGF-1 mRNA was localized to a few neurons, with no labeled cells in the dentate gyrus molecular layer; bFGF cRNA hybridization was diffuse in dendritic fields but was dense in CA2 stratum pyramidale. Both mRNA species were increased by deafferentation. The distribution of elevated IGF-1 mRNA corresponded precisely to fields of axonal degeneration and was greatest in the dentate gyrus outer molecular layer and stratum lacunosum moleculare. In these fields, IGF-1 mRNA was elevated by 2 days, reached maximal levels at 4 days, and declined by 10 days postlesion. Double labeling revealed that the majority of IGF-1 cRNA-labeled cells were microglia. In deafferented hippocampus, bFGF mRNA was broadly increased across fields both containing and lacking axonal degeneration. In the dentate, bFGF mRNA levels peaked at 5 days postlesion and remained elevated through 14 days. These results demonstrate that reactive microglia within deafferented hippocampal laminae express IGF-1 mRNA just prior to and during the period of reactive axonal growth and suggest that IGF-1 plays a role in directing the sprouting of spared afferents into these fields.

Basic fibroblast growth factor increases dopaminergic graft survival and function in a rat model of Parkinson's disease

The clinical use of fetal neural grafts as an intracerebral source of dopamine for patients with Parkinson's disease has met with limited success. Since basic fibroblast growth factor (bFGF) enhances the survival and growth of dopaminergic neurons in vitro, we explored whether cells genetically modified to produce bFGF would improve the functional efficacy of dopaminergic neurons implanted into rats with experimental Parkinson's disease. Results show that bFGF-producing cells grafted together with fetal dopamine neurons have potent growth-promoting effects on the implanted neurons in vivo. Moreover, rats implanted with such co-grafts display the most pronounced behavioural improvements post-grafting. These findings not only provide insight into the function of bFGF in situ, but also suggest an approach for enhancing the survival and function of dopamine neurons grafted into the damaged brain.

Transfection with bFGF sense and antisense cDNA resulting in modification of malignant glioma growth

Aberrant autocrine control by peptide growth factors is a possible mechanism by which disordered regulation of cell proliferation may occur. The authors used the C6 glioma cell line as a model to study the role of basic fibroblast growth factor (bFGF) in tumor growth by transfection with bFGF complementary deoxyribonucleic acid in both the sense and antisense orientation. Clones with high messenger ribonucleic acid expression of the sense construct have increased proliferation in cell culture and increased levels of intracellular and extracellular bFGF. Clones with high expression of the antisense construct show decreased proliferation in culture and reduced levels of immunologically detectable bFGF.

Basic fibroblast growth factor alterations during development of monocrotaline-induced pulmonary hypertension in rats

The chemical signaling pathways which orchestrate lung cell responses in hypertensive pulmonary vascular disease are poorly understood. The present study examined temporal alterations in lung basic Fibroblast Growth Factor (bFGF) in a well characterized rat model of monocrotaline (MCT)-induced pulmonary hypertension. By immunohistochemical analysis, there were progressive increases in bFGF in airway, vascular and gas exchange regions of MCT-treated rat lungs. Increases in bFGF preceded the onset of right ventricular hypertrophy at day 21 after MCT administration. Enhanced bFGF immunostaining was observed as early as day 4 in focal areas of the parenchyma, and by day 14 there was enhanced bFGF staining in alveolar macrophages, neutrophils and alveolar septa, which persisted through day 21. In conducting airways, there was elevated bFGF immunostaining in the smooth muscle cell (SMC) layer by days 4 and 7 and in the ciliated epithelium and its basement membrane at days 14 and 21. Cells morphologically similar to Clara cells in the luminal surfaces of bronchioles stained intensely on days 14 and 21. In the nucleus and cytoplasm of medial SMCs within pulmonary arteries, there was a progressive increase in bFGF staining starting at day 4. Lung bFGF mRNA was increased slightly at days 1, 4 and 7, while lung bFGF protein, as judged by western blot analysis, was increased at days 14 and 21 compared to controls. The present results, considered in teh light of teh documented roles of bFGF in vascular cell migration, growth and synthesis of extracellular matrix components, suggest that bFGF may contribute to the structural remodeling processes underlying the development of chronic pulmonary hypertension in MCT-treated rats.

Storage, metabolism, and processing of 125I-fibroblast growth factor-2 after intracerebral injection

Basic fibroblast growth factor (FGF-2) is a potent trophic agent for both neuronal and non-neuronal cells of the mammalian CNS. It can enhance survival and neurite outgrowth of a variety of neuronal types in vitro and in vivo, and recently has been shown to stimulate neuroblast proliferation in culture. To determine the most effective means of introducing FGF-2 into the brain, and to further our understanding of the behavior of exogenous FGF-2 following intracerebral injection, we examined the diffusion and degradation of 125I-FGF-2 following intraventricular or intraparenchymal injection. SDS-PAGE and autoradiography show that when radiolabelled FGF-2 is injected into the parenchyma of the rat brain, it remains at the site of injection where it is detectable for several days. During this time, it is slowly metabolized to 2 specific heparin-binding metabolic fragments that are virtually identical to the ones described for its metabolism by neurons and astrocytes in vitro. Microscopic examination and autoradiography of these tissue sections show that within these areas, FGF-2 diffuses throughout the site of injection. Initially, it migrates along adjacent fiber tracts, binds to specific cells and to basement membranes of the microvasculature, but later on it remains associated to basement membranes and non-neuronal cells. Based on its slow clearance and slow rate metabolic degradation, this FGF-2 is presumed to be in a sequestered form and to have limited activity. In contrast, the intraventricular injection of 125I-FGF leads to a rapid clearance, with some binding to ependymal cells lining the ventricles and little translocation into the parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-1 beta increases basic fibroblast growth factor mRNA expression in adult rat brain and organotypic hippocampal cultures

In situ hybridization was used to study the effect of IL-1 beta on acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) mRNA expression in rat brain. Intraventricular injection of recombinant human IL-1 beta did not affect hybridization to aFGF mRNA but did induce significant and widespread increases in hybridization to bFGF mRNA. IL-1 beta induced increases in bFGF mRNA were bilaterally distributed and appeared to correspond with the distribution of non-neuronal cells. Thus, hybridization was increased in regions of both gray and white matter (e.g., corpus callosum), the ependymal lining of the third ventricle, and the pia matter. In hippocampus of IL-1 beta injected rats, hybridization was markedly increased in the molecular layers but not significantly increased in the neuronal cell layers. Elevations in bFGF mRNA were transient, peaking at 8 h postinjection in most areas. To determine if IL-1 beta effects were independent of activation of the hypothalamo-pituitary-adrenal axis, and to compare the cellular localization of increases in bFGF mRNA expression induced by IL-1 beta and bFGF, the regulation of bFGF expression was also studied in organotypic hippocampal slice cultures. Treatment of cultures with either IL-1 beta or bFGF stimulated the same general distribution of increases in bFGF mRNA as seen after IL-1 beta treatment in vivo with an additional effect on immature neurons within the hilar side of stratum granulosum; hybridization of bFGF mRNA was not increased in association with the more mature neurons of stratum pyramidale or stratum granulosum. Colocalization of bFGF cRNA hybridization with immunostaining for glial fibrillary acidic protein demonstrated that increases in bFGF mRNA induced both by IL-1 beta in vivo and in vitro and by bFGF in vitro were largely associated with astroglial cells. These findings suggest that IL-1 beta induction of bFGF contributes to the coactivation of these substances following various forms of insult to the CNS and initiates a cascade of trophic interactions that regulates processes of glial proliferation, neurotrophic factor expression, and neuroprotection.

Steroidogenic adrenocortical cells synthesize alpha 2-macroglobulin in vitro, not in vivo

We previously identified alpha 2-macroglobulin as the major protein secreted by primary cultures of adrenocortical cells. We report here that in the adrenal gland, the distribution of alpha 2-macroglobulin in the adrenocortical tissue is restricted to the endothelium of blood vessels and that no immunoreactivity is found in steroidogenic cells. A time course study revealed that freshly dissociated bovine adrenocortical cells were void of alpha 2-macroglobulin immunoreactivity whereas the proportion of alpha 2-macroglobulin-positive cells reached more than two-thirds of the population between day 4 and day 7 of culture. Double immunoenzymatic labeling of 6-day-old cultures revealed a co-localization of alpha 2-macroglobulin and the steroidogenic enzyme P-450SCC. Treatment of 5-day-old cultures (expressing alpha 2-macroglobulin) for 24 h by either ACTH (10(-9)-10(-6) M) or alpha 2-macroglobulin (2.5 mg/ml) resulted in a marked decrease of the expression of alpha 2-macroglobulin. These data indicate that ACTH and plasmatic alpha 2-macroglobulin could physiologically repress alpha 2-macroglobulin expression in the adrenal cortex in vivo.

Basic fibroblast growth factor (FGF-2) in renal cell carcinoma, which is indistinguishable from that in normal kidney, is involved in renal cell carcinoma growth

To investigate the role of basic fibroblast growth factor (FGF) in renal cell carcinoma growth, we have analyzed the expression of mRNA of basic FGF. In 7 of 15 cases, basic FGF mRNA level in renal cell carcinoma tissues was higher than that in corresponding normal tissues. However, the tumor-to-normal ratios of expression levels are chiefly less than 2.0 and, in 5 cases, are even less than 1.0. Furthermore, there was no correlation between the ratio and the clinical stage. In protein analysis, we could not find any difference between basic FGF extracted from renal cell carcinomas and that from normal kidney tissues in bioactivity, immunoreactivity, molecular weight and affinity to heparin. On the other hand, anti-basic FGF monoclonal antibody inhibited the growth of a renal cell carcinoma cell line, VMRC-RCW, and this inhibition was reversed by an extraphysiological amount of exogenous basic FGF (100 ng./ml.). These results suggest that basic FGF itself may have no pivotal role in renal cell carcinoma etiology but is involved in the growth of renal cell carcinomas in an autocrine manner.