C-fos mRNA Content Research Articles

Effects of pyrroloquinoline quinone on proliferation and expression of c-fos, c-jun, CREB and PCNA in cultured Schwann cells

To investigate the effects of pyrroloquinoline quinine (PQQ) on proliferation and expression of c-fos, c-jun, CREB and PCNA in cultured Schwann cells. Schwann cells were cultured and purified in vitro. The purity of Schwann cells was identified by immunofluorescence of S-100. After synchronization of cell cycle by serum-free medium, different concentration of PQQ (0,1, 10, 100, 1,000, 10,000 nmol/L) were added into culture medium for 72 h. Flow cytometry was used to determine cell cycle. The content of c-fos, c-jun, and CREB mRNA were detected by RT-PCR, and the expression of PCNA protein was detected by Western blot. After PQQ treatment, the percentage of cells in G0/G1 phase decreased and the percentage of cells in S and G2/M phase increased. After treated by PQQ at concentration of 1-10,000nmol/L, content of c-fos,c-jun,CREB mRNA was increased by 0.33,0.42 and 0. 52 fold (P < 0. 05). However, at concentration of 1 000 nmol/L, there was no difference in mRNAs content when compare to control (P >0.05). And it showed a decline at concentration of 10,000 nmol/L (P < 0.05). PCNA protein expression was up-regulated at PQQ concentration of 1-100 nmol/L. At 100 nmol/L, the expression increased by 1.17 fold (P < 0.05); However, at 1,000 nmol/L, there was no difference in PCNA expression when compared to control. And 10,000 nmol/L of PQQ inhibited the expression of PCNA (P < 0.05). When treated with PQQ at concentration of 10-100 nmol/L, the proliferation of Schwann cells increased and the expression of c-fos,c-jun, CREB and PCNA was up-regulated.

High-Frequency Field Stimulation of Primary Neurons Enhances Ryanodine Receptor-Mediated Ca2+Release and Generates Hydrogen Peroxide, Which Jointly Stimulate NF-κB Activity

Neuronal electrical activity increases intracellular Ca(2+) concentration and generates reactive oxygen species. Here, we show that high frequency field stimulation of primary hippocampal neurons generated Ca(2+) signals with an early and a late component, and promoted hydrogen peroxide generation via a neuronal NADPH oxidase. Hydrogen peroxide generation required both Ca(2+) entry through N-methyl-D-aspartate receptors and Ca(2+) release mediated by ryanodine receptors (RyR). Field stimulation also enhanced nuclear translocation of the NF-κB p65 protein and NF-κB -dependent transcription, and increased c-fos mRNA and type-2 RyR protein content. Preincubation with inhibitory ryanodine or with the antioxidant N-acetyl L-cysteine abolished the increase in hydrogen peroxide generation and the late Ca(2+) signal component induced by electrical stimulation. Primary cortical cells behaved similarly as primary hippocampal cells. Exogenous hydrogen peroxide also activated NF-κB-dependent transcription in hippocampal neurons; inhibitory ryanodine prevented this effect. Selective inhibition of the NADPH oxidase or N-acetyl L-cysteine also prevented the enhanced translocation of p65 in hippocampal cells, while N-acetyl L-cysteine abolished the increase in RyR2 protein content induced by high frequency stimulation. In conclusion, the present results show that electrical stimulation induced reciprocal activation of ryanodine receptor-mediated Ca(2+) signals and hydrogen peroxide generation, which stimulated jointly NF-κB activity.

Immunocytochemistry and Laser Capture Microdissection for Real-time Quantitative PCR Identify Hindbrain Neurons Activated by Interaction Between Leptin and Cholecystokinin

Current evidence suggests that leptin reduces food intake in part by enhancing the hindbrain neuronal response to meal-related gastrointestinal signals, including cholecystokinin (CCK), but the phenotypes of the relevant cells are not known. To identify neurons that participate in this interaction in the rat nucleus of the solitary tract (NTS), we induced c-Fos gene expression in NTS neurons with leptin and CCK. We focused on NTS catecholamine neurons because these cells have been implicated in the feeding response to CCK. Hindbrain sections from rats that received CCK with or without leptin pretreatment were immunostained for c-Fos and tyrosine hydroxylase (TH) by a double immunofluorescence procedure. Leptin pretreatment increased the number of NTS cells expressing c-Fos-like immunoreactivity (cFLI) 3-fold relative to CCK alone, but the number of TH-positive cells with cFLI was increased 6-fold. Next, cells detected by immunofluorescence for TH were collected by laser capture microdissection and pooled for real-time quantitative PCR of c-Fos mRNA. Here, neither le0ptin nor CCK alone affected the relative amount of mRNA in the TH cell-enriched samples, but leptin plus CCK substantially increased c-Fos mRNA content. These histochemical findings identify hindbrain catecholamine cells as potential mediators of the interaction between leptin and CCK.

Na+]i‐induced c‐Fos expression is not mediated by activation of the 5′‐promoter containing known transcriptional elements

In vascular smooth muscle cells and several other cell types, inhibition of Na(+)/K(+)-ATPase leads to the expression of early response genes, including c-Fos. We designed this study to examine whether or not a putative Na(+) (i)/K(+) (i)-sensitive element is located within the c-Fos 5'-UTR from - 650 to + 103 containing all known response elements activated by 'classic' stimuli, such as growth factors and Ca(2+) (i)-raising compounds. In HeLa cells, the highest increment of c-Fos mRNA content was noted after 6 h of Na(+)/K(+)-ATPase inhibition with ouabain that was abolished by actinomycin D, an inhibitor of RNA synthesis. c-Fos protein accumulation in ouabain-treated cells correlated with a gain of Na(+) (i) and loss of K(+) (i). Augmented c-Fos expression was also observed under inhibition of Na(+)/K(+)-ATPase in K(+)-free medium and in the presence of the Na(+) ionophore monensin. The effect of ouabain on c-Fos expression was sharply attenuated under dissipation of the transmembrane Na(+) gradient, but was preserved in the presence of Ca(2+) chelators and the extracellular regulated kinase inhibitor PD98059, thus indicating an Na(+) (i)-mediated, Ca(2+) (i)- and extracellular regulated kinase-independent mechanism of gene expression. In contrast to massive c-Fos expression, we failed to detect any effect of ouabain on accumulation of luciferase driven by the c-Fos 5'-UTR. Negative results were also obtained in ouabain-treated vascular smooth muscle cells and C11 Madin-Darby canine kidney cells possessing augmented c-Fos expression. Our results reveal that Na(+) (i)-induced c-Fos expression is not mediated by the 5'-UTR containing transcriptional elements activated by growth factors and other 'classic stimuli'.

The endogenous lipid oleamide activates serotonin 5-HT7 neurons in mouse thalamus and hypothalamus.

Oleamide is an endogenous lipid that accumulates during sleep deprivation and has hypothermic effects when administered to rodents. The mechanisms for its activity remain unknown. Intraperitoneal injections of oleamide elicited dramatic increases in content of c-fos mRNA and Fos protein in distinct brain regions, including cingulate and somatosensory cortical areas and numerous nuclei of the thalamus and hypothalamus, indicating that there are explicit targets for its action. In the thalamus and hypothalamus a majority of neurons induced for c-fos expression also expressed the serotonin 5-HT7 receptor, an allosteric target for oleamide in in vitro studies. These data suggest that oleamide may act at 5-HT7 receptors to elicit alterations in transcription that result in some of its physiological effects.

Variations of progesterone receptor and c-fos gene expression in the rat uterus after treatment with norethisterone and its A-ring reduced metabolites

It has been suggested that some contraceptive derivatives of 19-nor-testosterone possess estrogenic activity that may facilitate the development of breast cancer. The aim of this work was to investigate the estrogenic properties of norethisterone (NET) and its A-ring–reduced derivatives by determining progesterone receptor (PR) and c-fos mRNA content of two estrogen-regulated genes in the uterus of ovariectomized rats. mRNA content was evaluated by Northern blot 1–6 h after 17β-estradiol administration. The highest PR and c-fos mRNA content was observed 3 h and 2 h after 17β-estradiol administration, respectively. NET did not modify either PR or c-fos mRNA content. In contrast, 5α- and 3β,5α-NET significantly increased mRNA content of both genes. The increase in c-fos mRNA content induced by these reduced compounds was lower than that found with estradiol treatment. The overall results indicate that NET administration can indirectly induce estrogenic effects through the action of its 5α-dihydro and 3β,5α-tetrahydro derivatives.

Differential expression of the estrogen-regulated proto-oncogenes c-fos, c-jun, and bcl-2 and of the tumor-suppressor p53 gene in the male mouse chronically infected with Taenia crassiceps cysticerci.

Chronic infection with Taenia crassiceps cysticerci produces a 200-fold increase in serum estradiol levels in male mice. The aim of this study was to investigate the expression pattern of c-fos and c-jun, two estradiol-regulated genes, as well as that of p53 and bcl2 in the testes, spleen, and thymus of male mice infected with T. crassiceps cysticerci. In parasitized animals the c-fos mRNA content was significantly increased in all tissues studied, whereas the c-jun mRNA content was increased only in the thymus. The p53 mRNA content was markedly reduced in all tissues of the parasitized animals analyzed, whereas bcl-2 gene expression was abolished in the thymus. On the other hand, thymic cell analysis performed by flow cytometry showed a diminution in the content of CD3+, CD4+, and CD8+ subpopulations in the parasitized mice. Our results suggest that the increase in estradiol levels of the host should change the expression pattern of several genes that participate in apoptosis regulation in the thymus of male mice during chronic infection with T. crassiceps cysticerci.

Temporal analysis of changes in neuronal c-fos mRNA levels induced by depletion of endoplasmic reticulum calcium stores: effect of clamping cytoplasmic calcium activity at resting levels.

Activation of immediate early gene expression is a key event in stress-induced neuronal cell injury. To study whether changes in cytoplasmic calcium activity are necessary to activate neuronal immediate early gene expression, endoplasmic reticulum (ER) calcium stores of primary neurons were depleted by exposing cells to thapsigargin (Tg), an irreversible inhibitor of ER Ca2+-ATPase. Tg-induced rise in [Ca2+]i and the effect of loading neurons with the cell-permeable calcium chelator BAPTA-AM on this increase in [Ca2+]i were measured in fura-2-loaded cells by fluorescence microscopy. Changes in c-fos mRNA levels were evaluated by quantitative PCR. Tg treatment of neurons produced a pronounced rise in c-fos mRNA levels (approximately 10-fold more than DMSO) which peaked at 1 h after exposure. The Tg-induced rise in c-fos mRNA content was unchanged (hippocampal neurons) or even increased further (cortical neurons) by preloading cells with BAPTA before incubation with Tg. It is concluded that in neuronal cells an increase in cytoplasmic calcium activity is not a prerequisite for a rise in mRNA levels of c-fos. Thus, stress-induced changes in mRNA levels of immediate early genes of neurons may also result from disturbances in ER calcium homeostasis and not necessarily by an overload of cells with calcium ions. The results of the present series of experiments cast further doubt on the widely accepted hypothesis that the stress-induced cytoplasmic overload of neurons with calcium ions is the primary event triggering cell injury.

Differential patterns of c-fos mRNA expression in amygdala during successive stages of odor discrimination learning.

Expression of the activity-dependent gene c-fos was used to assess relative levels of neuronal activation in the amygdala and related structures of rats at different stages of odor discrimination learning. In situ hybridization was used to evaluate c-fos mRNA content within the amygdalar subdivisions, the bed nucleus of the stria terminalis, and the hippocampus. After initial exploration of the test apparatus, c-fos mRNA levels were increased in the medial and, to lesser extent, basolateral subdivisions and remained low in the central division. The balance of amygdala to hippocampal labeling favored hippocampus. Rats engaged in familiar nose-poke responses had comparably elevated labeling in the medial and basolateral divisions and low labeling densities in the central division. The ratio of hippocampal to amygdala labeling was at control levels. Rats required to switch from ad libitum responding to cued responding to odors had high basolateral to medial labeling ratios. This was in marked contrast to the medial dominance found in control and exploration rats. Hybridization was substantially more dense in basolateral amygdala than in hippocampal CA1; this imbalance was unique to the group required to form first associations between odors and rewards. Rats performing an overtrained odor discrimination had the least differentiation between amygdalar subdivisions of any behavioral group. The hippocampus-to-amygdala labeling ratio favored hippocampus and was nearly identical to the ratio in exploration rats. These results demonstrate that the balance of activity within the between limbic structures shifts according to behavioral demands. It is suggested that the balances reflect the availability of pertinent afferent cues, interactions between hippocampus and the extended amygdala, and relative levels of activity in the diffuse projections to the limbic system.

Prolonged alkylcatechol‐induced expression of c‐jun proto‐oncogene followed by elevation of NGF mRNA in cultured astroglial cells

We have already shown that alkylcatechol markedly enhances synthesis/secretion of nerve growth factor (NGF) in cultured mouse fibroblasts and astroglial cells through immediate accumulation of NGF mRNA and that the stimulatory effect of alkylcatechol on NGF synthesis/secretion is synergistically enhanced by the coadministration of phorbol 12-myristate 13-acetate (PMA). The stimulatory effect on NGF mRNA expression of astroglial cells in culture by 4-methylcatechol (MC), an alkylcatechol, and/or PMA was blocked by treatment of the cells with cycloheximide, suggesting de novo synthesis of some cellular protein(s) is essential for the observed increase in the NGF mRNA level. The exposure to MC and/or PMA caused a rapid increase in c-fos mRNA content, which was immediately followed by an increase in c-jun mRNA, prior to NGF mRNA elevation. The expression of c-fos mRNA was transiently enhanced in all cases of the treatment with MC and/or PMA. The c-jun mRNA expression was also observed transiently when the cells were treated with PMA alone, while the expression of c-jun mRNA was pronounced and long-lasting after the treatment with MC, which was much further enhanced by the coadministration of PMA. The result that the profile of the change in c-jun mRNA expression resembled that in NGF mRNA expression suggests that the increase in c-jun mRNA is responsible for the subsequent increase in NGF mRNA after MC treatment. The contransfection of mouse astroglial cells with expression plasmids of c-fos and/or c-jun and NGF promoter gene showed that simultaneous expression of both c-fos and c-jun genes was necessary to enhance NGF promoter activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertrophic growth of cultured neonatal rat heart cells mediated by type 1 angiotensin II receptor.

Primary cultures of neonatal cardiac myocytes were used to determine the identity of second messengers that are involved in angiotensin II (ANG II) receptor-mediated effects on cardiac hypertrophy and the type of ANG II receptor that is involved in ANG II-induced cell growth. Treatment of myocytes with ANG II significantly increased the protein-to-DNA and the RNA-to-DNA ratios. ANG II accelerated rates of protein synthesis by 24.9%. Intracellular free calcium was transiently increased after ANG II exposure. The activity of protein kinase C in particulate fractions was transiently increased after exposure to ANG II but returned to control level. The activity of protein kinase C in the cytosol was significantly decreased at all times after exposure to ANG II. After ANG II treatment, the content of c-Fos mRNA was increased. The stimulatory effects of ANG II on these parameters were inhibited by the type 1 angiotensin II receptor (AT1) antagonist, losartan. These studies demonstrate that ANG II-induced hypertrophic growth is, at least in part, mediated through AT1 receptors.

Desensitization of c-fos mRNA Expression in Rat Brain Following Cortical Lesions

The effect of cortical lesions on the c-fos mRNA expression in adult rat brain was studied using in situ hybridization and Northern blot analysis. It was observed that the single cortical lesion evoked a rapid increase in the content of c-fos mRNA in whole brain. However, when rats received a second and third cortical injury 4 and 8 h after the first one, there was reduced elevation of c-fos mRNA after the second (60%) and third (75%) injuries in comparison with those seen after a single cortical lesion. These results represent the desensitization period during which the induction of c-fos mRNA by repeated cortical lesions was decreased. On the contrary, when animals were treated with a fourth cortical lesion 24 h after the first injury, with recovery for 16 h after the third one, the levels of c-fos mRNA were again elevated to a degree almost comparable to that seen after the single injury alone. The anatomical distribution of c-fos mRNA-expressing cells after cortical lesions revealed a large increase of hybridization to a heterogeneous population of hippocampal neurons including small cells of stratum granulosum in the dentate gyrus and larger cells within hippocampal stratum pyramidale. A dramatic labeling of neurons with c-fos riboprobe in frontoparietal and piriform cortex was also observed but with predominantly localized hybridization to c-fos mRNA on the damaged side of the cortex following the first and second cortical injury. However, hippocampal distribution of c-fos mRNA-containing cells was bilateral as a result of polysinaptic potentials evoked by cortical lesions.

Differential effects of amiloride on the basal rate and the pressure overload-induced increase in protein synthesis in perfused rat heart.

The purpose of the present study were to determine the contribution of Na+/H+ exchange to pressure overload-induced cardiac hypertrophy and to examine its potential interaction with cAMP-dependent signaling pathway. Isolated rat hearts were perfused as Langendorff preparations with aortic pressure of 60 mmHg. In pressure overload group, aortic pressure was increased to 120 mmHg. cAMP contents in the heart perfused at 2 min were examined by RIA. Rates of protein synthesis were examined by 14C-phenylalanine incorporation into myocardial protein during the second hour of perfusion. Expression of c-fos mRNA in the heart perfused at 1 hour was analyzed by Northern blotting. Elevation of aortic pressure from 60 mmHg to 120 mmHg in perfused rat hearts increased cAMP contents from 4.89 +/- 0.09 to 6.30 +/- 0.28 pmol/mg protein and accelerated rates of protein synthesis from 644 +/- 13 to 860 +/- 49 mmol Phe/g dry heart/hr. Expression of c-fos mRNA was induced by elevated aortic pressure. Amiloride, an inhibitor of Na+/H+ exchange, decreased rates of protein synthesis in a concentration-dependent manner (12.5, 25, 50, 100 microM) but did not change cAMP content (5.25 +/- 0.11 pmol/mg protein) or expression of c-fos mRNA. Furthermore, amiloride did not prevent the increases in cAMP (6.99 +/- 0.34 pmol/mg protein), protein synthesis rates (476 +/- 18 to 689 +/- 31 nmolPhe/g dry heart/hr) and expressions of c-fos mRNA that were induced by elevation of aortic pressure. These results indicate that amiloride, an inhibitor of Na+/H+ exchange system, while influencing rates of protein synthesis, does not play an important role in pressure overload-induced cardiac hypertrophy. The mechanism by which amiloride influences cardiac protein synthesis is independent of the cAMP-dependent mechanism by which pressure overload induces cardiac hypertrophy.

Induction and Desensitization of the c-Fos mRNA Response to Nicotine in Rat Brain

Early rapid response genes such as c-fos are activated in the central nervous system by a variety of agents including psychostimulants. In the present studies, we investigated changes in c-fos mRNA content in several brain regions of the rat in response to nicotine. A single injection of nicotine ip increased the c-fos mRNA content within 30 min and returned toward baseline by 120 min. Significant elevations were induced by 0.5 mg/kg bw nicotine in the medial habenula and by 1.0 mg/kg in the hippocampus, dentate gyrus, and piriform cortex. At 1.0 mg/kg, significantly greater increases in c-fos mRNA levels were present in medial habenula and hippocampus compared to dentate gyrus and in dentate gyrus compared to piriform cortex. Moreover, at 1.0 mg/kg nicotine, increases were significantly less in cerebellar cortex and cingulate gyrus, and these were not dose-dependent. Mecamylamine, a nicotinic cholinergic receptor antagonist, significantly attenuated or eliminated c-fos mRNA response to 1.5 mg/kg nicotine in all regions, except in the cerebellar cortex. Desensitization of the c-fos mRNA response to nicotine was investigated by administering two injections of 2.0 mg/kg nicotine 2 h apart. In the hippocampus, dentate gyrus, and piriform cortex, the first dose of nicotine significantly reduced the c-fos mRNA response to a second dose. The magnitude of desensitization ranged from 43% (piriform cortex) to 81% (hippocampus). In summary, nicotine rapidly elevated the c-fos mRNA content in several rat brain regions. The sensitivity of this response to nicotine and development of desensitization differed among the regions.

Timing of protooncogene expression varies in toxin‐induced liver regeneration

Hepatic expression of the protooncogenes c-fos and c-myc occurs within 2 h after partial hepatectomy, and these immediate early genes are thought to prime the hepatocytes for subsequent proliferation. To examine whether such gene activation occurred in the setting of hepatocyte proliferation after toxic liver injury, protooncogene expression was examined during the regenerative response following liver injury from carbon tetrachloride (CCl4) or galactosamine (GalN). The pattern of protooncogene expression after CCl4 mirrored that seen after partial hepatectomy, with rises in c-fos and c-myc mRNA content within 2 h, and then a rapid return to baseline levels. In contrast, early c-fos and c-myc expression did not occur after GalN injury. Instead GalN-induced regeneration led to a delayed, and prolonged c-fos and c-myc activation which peaked 24-48 h after injury. Increases in c-jun, jun-B, and jun-D mRNA levels also occurred in both models at times similar to the rises of c-fos and c-myc expression. Although the timing of DNA synthesis was identical after GalN or CCl4 treatment, the proliferative response after GalN injury was significantly less than that of CCl4, and marked by the histologic appearance of oval cells. The coadministration of 2-acetylaminofluorene, an inhibitor of differentiated hepatocyte proliferation, together with CCl4 altered the usual pattern of post-CCl4 protooncogene expression to one resembling that seen after GalN injury. Thus, the timing of protooncogene expression during liver regeneration may vary considerably. These variations may influence the nature of the proliferative response in terms of which cell type(s) proliferates, and the amount of regeneration that ensues.

Temporal and spatial preferences of c- fos mRNA expression in the rat brain following cortical lesion

The expression of the proto-oncogene c-fos is increased in neuronal cells by a number of stimuli and the usefulness of this gene as a marker of neuronal activity has been demonstrated. The temporal and spatial expression of c-fos mRNA following the induction of a unilateral cortical lesion have been investigated in the rat brain by Northern blot analysis and in situ hybridization histochemistry. It was observed that the lesion evoked a rapid increase (20-fold) in the content of c-fos mRNA in the ipsilateral cortex, whereas in the contralateral cortex c-fos mRNA expression was more modest (7-fold). In the whole hippocampus a large and very rapid increase (17-fold) of c-fos mRNA expression was detected. The effect of a cortical lesion on Ca2+ uptake and membrane potential was also investigated. Using synaptosomes as a model system, we have provided evidence that Ca2+ entry via membrane depolarization increases in coordination with c-fos gene expression in neuronal cells. The principal conclusions from this study are that cortical lesions induce transient expression of the c-fos gene in specific neuronal cells of the rat brain.

The regulation by growth hormone of lipoprotein lipase gene expression is mediated by c-fos protooncogene.

GH has been previously shown in Ob1771 adipose cells to activate transiently the expression of c-fos gene by a protein kinase-C-dependent pathway and to modulate, at last in part by a protein kinase-C-dependent pathway, the expression of the lipoprotein lipase (LPL) gene. In Ob1771 cells exposed to GH, under conditions where protein synthesis is inhibited by cycloheximide, the modulation of LPL gene expression is prevented, suggesting that synthesis of trans-acting factor(s) is required to modulate LPL gene expression. The present results indicate the involvement of c-Fos protein in this modulation; this involvement is supported by various lines of evidence: 1) upon GH stimulation, the increase in c-fos mRNA content is followed by the emergence of c-Fos protein within the nucleus, and this emergence precedes the increase in LPL mRNA content; 2) in GH-treated Ob1771 cells, exposure to antisense sof oligonucleotides abolishes the synthesis of c-Fos protein; and 3) at the same time, the increase in LPL mRNA content and LPL activity does not occur, whereas sense fos oligonucleotides show no effect. It is concluded that c-Fos protein plays an intermediary role in the modulation of LPL gene expression by GH.

The presence of functional estrogen receptors in intestinal epithelial cells.

Reproductive and maturational nutritive needs are examples of situations in which alterations in circulating concentrations of estrogens are associated with changes in intestinal epithelial function. However, it is not clear that any of these effects is due to direct interaction of estrogen with intestinal epithelial estrogen receptors (ER). The experiments reported here were designed to determine whether the small intestinal epithelium contains functional ER and might, therefore, be an estrogen-responsive tissue. IEC-6 cells, a non-transformed line of cells isolated from rat small intestinal crypts, were used for many of the experiments, because they provide a pure preparation of crypt epithelial cells. IEC-6 cells were found to exhibit specific saturable binding of estradiol with a Kd of 5 x 10(-10) M and approximately 100 binding sites/cell. Reverse transcriptase-polymerase chain reaction demonstrated that IEC-6 cells as well as epithelial cells from each segment of the rat intestine (duodenum, jejunum, ileum, and colon) contained ER mRNA of the sequence determined from rat uterus. Estradiol was shown to stimulate IEC-6 cell c-fos mRNA content rapidly and transiently in a manner analogous to that which has been previously demonstrated for other estrogen-responsive tissues. These data demonstrate that intestinal epithelial cells contain ER capable of regulating gene transcription and provide the basis for future studies designed to elucidate the role of estrogens in the regulation of intestinal epithelial function and pathophysiology.

The presence of functional estrogen receptors in intestinal epithelial cells

Reproductive and maturational nutritive needs are examples of situations in which alterations in circulating concentrations of estrogens are associated with changes in intestinal epithelial function. However, it is not clear that any of these effects is due to direct interaction of estrogen with intestinal epithelial estrogen receptors (ER). The experiments reported here were designed to determine whether the small intestinal epithelium contains functional ER and might, therefore, be an estrogen-responsive tissue. IEC-6 cells, a non-transformed line of cells isolated from rat small intestinal crypts, were used for many of the experiments, because they provide a pure preparation of crypt epithelial cells. IEC-6 cells were found to exhibit specific saturable binding of estradiol with a Kd of 5 x 10(-10) M and approximately 100 binding sites/cell. Reverse transcriptase-polymerase chain reaction demonstrated that IEC-6 cells as well as epithelial cells from each segment of the rat intestine (duodenum, jejunum, ileum, and colon) contained ER mRNA of the sequence determined from rat uterus. Estradiol was shown to stimulate IEC-6 cell c-fos mRNA content rapidly and transiently in a manner analogous to that which has been previously demonstrated for other estrogen-responsive tissues. These data demonstrate that intestinal epithelial cells contain ER capable of regulating gene transcription and provide the basis for future studies designed to elucidate the role of estrogens in the regulation of intestinal epithelial function and pathophysiology.

Acidic fibroblast growth factor modulates gene expression in the rat thyroid in vivo.

We have recently demonstrated that the iv administration of acidic fibroblast growth factor (a-FGF) to rats for 6 days results in a marked increase in thyroid weight with colloid accumulation and flat, quiescent follicular cells. Whereas a-FGF administration consistently increases thyroid weight, there are only minor alterations in serum TSH and thyroid hormones, and no change in intrathyroidal metabolism of 125I metabolism. In the present work, we studied the effects of 1 or 6 daily injections of a-FGF (60 micrograms/kg BW) or vehicle on the mRNA levels for histone, c-fos, actin, type I 5' deiodinase (5'D-I), thyroid peroxidase, and thyroglobulin and cathepsin D in the thyroid, liver and bone. Rats were sacrificed 0.5, 2, 4, 8 and 24 h after the 1st or the 6th a-FGF injection and thyroid, liver, and calvarium were removed. The relative amounts of mRNAs were determined by slot blot analysis. There was a 43% increase in thyroid weight in rats treated with a-FGF for 6 days compared to vehicle-treated rats. We observed an increase in c-fos mRNA content in the thyroid gland 0.5 to 4 h after 1 or 6 injections of a-FGF. In contrast, treatment with a-FGF for 1 or 6 days did not affect histone mRNA content, a marker of proliferative activity or actin mRNA levels. Treatment with a-FGF caused a marked decrease in thyroid 5' D-I mRNA content in the thyroid. The decrease was present 2 h after the first injection and reached a nadir 8 h later.(ABSTRACT TRUNCATED AT 250 WORDS)