Biomedical subjects

A R Morrison

Publications and source records attributed to A R Morrison.

At least 55 records · Page 3Linked to original sources

PubMed1996

Interleukin-1 beta activates c-jun NH2-terminal kinase subgroup of mitogen-activated protein kinases in mesangial cells.

We investigated whether JNK is activated by interleukin-1 beta (IL-1 beta) in mesangial cells. We performed in-gel kinase assays with His-c-jun-(1-79), which contains the amino-terminal activation domain of c-jun and a mutant His-c-jun in which Ser-63 and Ser-73 of His-c-jun were mutated to Ala as the substrates. JNK1 (p45) and JNK2 (p54) isoforms phosphorylated His-c-jun in mesangial cells. IL-1 beta produced a time- and concentration-dependent increase in JNK activity. IL-1 beta did not phosphorylated the mutant, His-c-jun. The IL-1 beta-activated JNK activity was independent of serum and suppressed by neither tyrosine kinase inhibitors nor protein kinase C inhibitors. JNK was also stimulated by anisomycin and okadaic acid but not by phorbol 12-myristate 13-acetate. The protein synthesis inhibitors and okadaic acid potentiated the IL-1 beta-induced JNK activity. Together, these studies indicate that the novel JNK group of protein kinases may play an important role in the signal transduction pathway initiated by proinflammatory cytokines, such as IL-1 beta in mesangial cells.

Animals↗

PubMed1996

Relationship of ventricular tachycardia to sleep/wakefulness in a model of sudden cardiac death.

Death from some childhood disorders such as sudden infant death syndrome and the congenital long QT syndrome are associated with specific behaviors such as sleep or emotional stress. We studied young German shepherd dogs that die suddenly during presumed sleep. These dogs have inherited ventricular tachycardia (VT) which is most frequent during sinus bradycardia and sinus arrhythmia. We hypothesized that the number of VT complexes (three or more consecutive ectopic complexes) would be greatest during sleep. Moreover, we hypothesized that pauses in the sinus rhythm of greater than 1000 ms would be greatest in the behavior with the most frequent VT. Behavioral states [excited, ambulatory, sitting, lying, rapid eye movement (REM) sleep] were quantified from 24-h video recordings of seven dogs. VT and pauses were quantified for each behavior using simultaneously recorded ECGs. A multivariate model was used to analyze the results. After controlling for time of day, lying, and REM sleep were significantly (p < 0.02) associated with VT, whereas more active behaviors were not. Time of day also independently affected the number of VT complexes. However, behavior and time of day did not account for all of the variability in the number of VT complexes. Pauses were significantly associated with behavior, with the highest number of pauses occurring during lying and REM sleep. However, pauses were not always associated with VT, indicating that a pause was a necessary, but not sufficient, condition for the development of VT. These results suggest that modulation of VT incidence in these animals is multifactorial and that the highest number of VT complexes is associated with the bradycardia that accompanies REM sleep.

Animals↗

PubMed1996

Enhanced prostaglandin synthesis after ultraviolet-B exposure modulates DNA synthesis of lens epithelial cells and lowers intraocular pressure in vivo.

PURPOSE: To study the functional significance of prostaglandin synthesis after ultraviolet-B (UVB) exposure of cultured human lens epithelial cells and rabbit eyes in vivo. METHODS: Prostaglandin E2 (PGE2) was assayed using a radioimmunoassay (RIA) and mass spectroscopy. An immortalized human lens epithelial cell line (HLE-B3) was exposed to UV irradiation, and the synthesis of PGE2 was compared with the rabbit lens epithelial cell line N/N1003A. Intact human lenses were exposed to UVB in organ culture. [3H]Thymidine incorporation was measured in cultured lens epithelial cells by incubation with the radiolabel. The effects of isobutyl methyl xanthine (IBMX), an inhibitor of phosphodiesterase and of dibutyryl cyclic adenosine monophosphate (cAMP), an analog of cAMP, on PGE2 synthesis and DNA synthesis, were determined. Rabbit eyes were exposed to UVB radiation in vivo. Intraocular pressure was measured at specific times after exposure. Aqueous humor was remove from rabbit eyes, and its PGE2 content was measured by RIA. RESULTS: Cultured human lens epithelial cells (HLE), like rabbit lens epithelial cells (RLE), showed a dose-dependent increase in basal PGE2 synthesis 24 hours after UVB exposure. However, the amount of PGE2 synthesis was 2000-fold higher in the rabbit cells. Ultraviolet-B radiation enhanced the incorporation of [3H]thymidine in lens epithelial cells. Pretreatment of cells with indomethacin reduce PGE2 synthesis and [3H]thymidine incorporation. The human and rabbit cells responded in a similar manner to changes in DNA synthesis after UVB exposure. The addition of IBMX or dbcAMP to indomethacin-treated, UVB-exposed cells restored DNA synthesis toward the levels observed in the UVB-exposed cells. An increase in the concentration of cAMP was observed in lens epithelial cells exposed to exogenous PGE2. PGE2 synthesis in intact human lenses also increased twofold 24 hours after UVB exposure. Exposure of the rabbit eye in vivo to an optimal dose of UVB produced an increase in the PGE2 levels of the lens and the aqueous humor. Measurements of the intraocular pressure (IOP) of the animals showed a decrease in IOP by 2.21 +/- 0.66 and 6.45 +/- 0.79 mm Hg (mean +/- SEM, P = 0.004, t-test) at 6 and 24 hours after UVB exposure, respectively. The decrease in IOP was prevented by pretreatment with indomethacin. Exposure of the rabbit lens to UVB radiation in vivo enhanced [3H]thymidine incorporation twofold into the lens. Pretreatment of rabbits with indomethacin before exposure reduced this response. CONCLUSIONS: Results indicate that UVB exposure enhances PGE2 synthesis in HLE cultures as well as in rabbit lenses irradiated in vivo. This increased PGE2 synthesis is related to the increase in DNA synthesis observed after UVB treatment. The modulation of DNA synthesis in cultured lens epithelial cells after UVB exposure may be mediated by a cAMP-dependent mechanism.

1-Methyl-3-isobutylxanthine↗

PubMed1996

The role of prostaglandins E2 and F2 alpha in ultraviolet radiation-induced cortical cataracts in vivo.

PURPOSE: Previous work has shown that exposure of lens epithelial cells or rabbit eyes in vivo to ultraviolet B (UVB) radiation enhanced prostaglandin (PG)E2 synthesis. Such enhanced PGE2 synthesis was related to the increased DNA synthesis that followed UVB exposure. The current study examined the relationship between enhanced prostaglandin synthesis and UVB-induced cataract formation. METHODS: Seventy albino (New Zealand white) rabbit eyes were exposed to UVB radiation in vivo. Fluence of radiation at the cornea was 2.8 J/cm2, 5.6 J/cm2, or 11.2 J/cm2. Eyes were examined 24 hours after UVB exposure and for as long as 10 days by slit lamp biomicroscopy. Mass spectrometry was used to measure PGE2, PGF2 alpha, and 6-keto-PGF1 alpha content of the lens and iris-ciliary body using authentic standards. To determine the effect of inhibition of prostaglandin synthesis on UVB-induced cataract formation, animals were given indomethacin intraperitoneally. Other pharmacologic agents, such as PGE2, PGF2 alpha, and misoprostol, were applied topically to the eye. The effect of UVB on K+ pump was determined by incubating isolated lenses with [86Rb+]. RESULTS: Twenty-four hours after UVB exposure, PGE2 and PGF2 alpha concentrations in aqueous humor were increased by 100- and 30-fold, respectively. Lens PGE2 and PGF2 alpha increased by 6- and 4-fold, respectively, after UVB radiation exposure. Pretreatment of animals with indomethacin prevented the rise in lens and aqueous humor PGE2 and PGF2 alpha levels. Furthermore, indomethacin was partially protective against UVB cataract formation and lowered cataract severity from stage 3 to stage 1, but it did not prevent UVB-induced lens changes completely. Topical application of PGE2 before UVB exposure completely prevented cataract formation in the UVB-exposed eye. In contrast, topical administration of PGF2 alpha increased cataract severity. UVB-induced cataract formation preceded changes in [86Rb]+ uptake in lenses subsequently incubated in K(+)-free Tyrode's. CONCLUSIONS: Enhanced synthesis of cyclooxygenase products of arachidonic acid metabolism in the lens is associated with UVB-induced cataract formation in albino rabbit eyes, and inhibition of cyclooxygenase by indomethacin decreased the severity of cataracts. PGE2, the principal arachidonic acid metabolite, appears to have a protective role because pretreatment of the eye with topical PGE2 completely prevented UVB-induced cataract formation, whereas PGF2 alpha increased the severity of the cataract. The evidence presented for a role of PGF2 alpha in the development of cataract suggests that caution be exercised in the use of PGF2 alpha derivatives in the therapy of glaucoma.

6-Ketoprostaglandin F1 alpha↗

PubMed1995

REM sleep inhibition by desipramine: evidence for an alpha-1 adrenergic mechanism.

The acute administration of drugs that block norepinephrine (NE) reuptake suppresses rapid eye movement (REM) sleep in cats and other mammals. The mechanism is presumed to involve NE acting on cells in a pontine REM sleep-generator region. Postsynaptic noradrenergic receptor mechanisms have not been identified. In the present experiments, we tested the ability of the alpha-1 antagonist prazosin and the beta antagonist propranolol to reverse the REM sleep suppression produced by the NE reuptake blocker desipramine (DMI) in the cat. DMI reduced the number of REM sleep episodes, the REM percentage (REM sleep time/total sleep time), and the average REM sleep episode duration. The co-administration of prazosin, but not propranolol, increased the REM percentage and the average REM sleep episode duration toward the placebo level. The co-administration of the peripherally-acting, anti-hypertensive agent hydralazine did not reverse the DMI-induced REM sleep suppression. While the identity of the brain region(s) involved in mediating the alpha-1 noradrenergic suppression of REM sleep by DMI remains unclear, there is reason to consider forebrain structures including the amygdala as well as the pontine areas that generally have been implicated in REM sleep control.

Adrenergic Uptake Inhibitors↗

PubMed1995

Regulation of heme oxygenase mRNA in mesangial cells: prostaglandin E2 negatively modulates interleukin-1-induced heme oxygenase-1 mRNA.

Heme oxygenase (EC 1.14.99.3) is the rate-limiting enzyme in heme catabolism. Several lines of evidence suggest a possible role for heme oxygenase in the inflammatory process and in cellular signaling. We have evaluated the regulation of heme oxygenase-1 mRNA induction by the inflammatory stimuli, phorbol 12,13-myristate acetate, heat shock and interleukin-1 beta in cultured rat mesangial cells. Phorbol 12,13-myristate acetate and heat shock rapidly (maximal at 2-3 hrs) induced heme oxygenase-1 mRNA. The effect of interleukin-1 beta on heme oxygenase-1 mRNA induction was slower (maximal at 12 hrs) and modest. However, in the presence of a cyclooxygenase inhibitor, indomethacin, interleukin-1 beta strongly induced heme oxygenase-1 mRNA. The addition of exogenous PGE2 reversed the effect of indomethacin. These data suggest that pro-inflammatory stimuli increase heme oxygenase-1 mRNA expression in rat mesangial cells and that interleukin-1 beta-induced heme oxygenase-1 mRNA level is negatively modulated by PGE2.

Animals↗

PubMed1995

Stimulus-elicited behavior in rapid eye movement sleep without atonia.

Alert wakefulness (W) and rapid eye movement sleep (REM) are remarkably similar on several measures of brain activity, but 2 differences in REM are reduced sensory responsiveness and atonia in postural muscles. Pontine tegmental lesions create REM without atonia (REM-A), releasing motor behavior. In 9 cats, we studied the acoustic startle reflex (ASR), orienting (OR), and ponto-geniculo-occipital waves (PGOE) elicited by tones during W, REM, REM-A, and non-REM (NREM). OR occurred in W and REM-A, being most complete in cats with the most elaborate spontaneous behavior. ASR occurred in W, NREM, and REM-A in lesioned cats. In normal cats, ASR rarely appeared in NREM and REM. PGOE had similar characteristics in both groups. The similarity of REM to W is particularly obvious when cats lack motoneuronal inhibition.

Acoustic Stimulation↗

PubMed1995

IL-1 beta regulates rat mesangial cyclooxygenase II gene expression by tyrosine phosphorylation.

The pro-inflammatory cytokine, interleukin-1 beta, induces the mRNA for prostaglandin endoperoxide synthase II gene in renal mesangial cells. This inductive effect is selective for prostaglandin endoperoxide synthase II and not prostaglandin endoperoxide synthase I. In the present experiments IL-1 beta increased COX II mRNA, and this was inhibited by genistein and herbimycin A, both inhibitors of protein tyrosine kinases. The dose dependent effect of genistein on inhibition of mRNA for COX II correlated with the inhibition of the release of PGE2 into the media. Induction of COX II by interleukin-1 beta was mimicked by incubating the cells in the presence of a protein tyrosine phosphatase inhibitor, vanadate. These experiments also illustrate selective induction of COX II mRNA without induction of COX I mRNA. Western analysis utilizing antiphosphotyrosine antibodies demonstrated in whole lysates of mesangial cells treated with interleukin-1 beta that the transient phosphorylation of several proteins occurred. Interleukin-1 beta induced the transient phosphorylation of a protein of about 39/40 kD. Similarly, vanadate also produced a rapid and transient phosphorylation of a protein of about 39/40 kD in addition to other proteins. Immunoprecipitation of mesangial cell lysates with agarose conjugated antiphosphotyrosine antibody and Western analysis of precipitated proteins with anti-ERK2 antibody demonstrate that the 39/40 kD protein phosphorylated on tyrosine is ERK2 and suggests participation of one of the MAP kinase family of extracellular receptor kinases in IL-1 beta stimulated induction of the COX II gene.

Animals↗

PubMed1995

Tyrosine kinase activation is necessary for inducible nitric oxide synthase expression by interleukin-1 beta.

The inflammatory cytokine interleukin-1 (IL-1) induces the inducible form of nitric oxide synthase (iNOS) with an increase in nitric oxide in rat mesangial cells. However, the cellular mechanisms that underlie the induction of iNOS by IL-1 beta in mesangial cells has not been clarified. Because we have shown that tyrosine kinase inhibitors attenuate IL-1 beta-induced cyclooxygenase expression and prostaglandin production, we investigated the effect of tyrosine kinase inhibitors on IL-1 beta-induced nitrite production and iNOS mRNA expression in rat mesangial cells. The tyrosine kinase inhibitors genistein and herbimycin A attenuated IL-1 beta-induced nitrite production in a dose-dependent manner. In addition, both of these inhibitors blocked IL-1 beta-induced iNOS mRNA expression. These data suggest that tyrosine kinase(s) plays a central role in IL-1 beta signaling to induce iNOS in rat mesangial cells.

Amino Acid Oxidoreductases↗

PubMed1995

Metabolic effects of fatty acid-bearing albumin on a proximal tubule cell line.

In glomerular disease, fatty acids carried on albumin are taken up by the proximal tubule with filtered albumin. We postulate that the fatty acids carried on filtered albumin could contribute to the deleterious effects of proteinuria. The effects of fatty acid-albumin complexes on lipid metabolism have been studied in opossum kidney (OK) cells, a proximal tubule cell line. OK cells transported two-thirds of [14C]palmitate-albumin (5 mg/ml) intracellularly within 16 h. [14C]palmitate-albumin was distributed into phosphatidylcholines, phosphatidylinositols, and tri- and diglycerides. 14C-labeled unsaturated fatty acid albumins (oleate, linoleate, and arachidonate) showed preferential incorporation into triglycerides, with lesser incorporation into phospholipids. Studies of total lipid pools showed that fatty acid-albumin uptake produced a particularly marked increase in total triglyceride levels (approximately 10-fold). Oil red O staining of OK cells cultured with oleate-albumin showed a marked increase in intracellular lipid droplets, compared with cells cultured with delipidated albumin, consistent with triglyceride accumulation. Less than 1% of [14C]palmitate taken up was isolated as intracellular free fatty acid. Less than 5% of [14C]palmitate internalized was oxidized to 14CO2. Different fatty acids, when taken up by the OK cell, have distinct metabolic fates. Each fatty acid is incorporated in a characteristic fashion into certain complex lipids, possibly dependent on the presence or absence of double bonds. We propose that this may have functional consequences for the proximal tubule in the human nephrotic syndrome.

Animals↗

PubMed1995

Interleukin-1 beta induces interstitial collagenase gene expression and protein secretion in renal mesangial cells.

Degradation and tissue remodeling of the extracellular matrix in the normal glomerulus occur through the coordinate action of neutral metalloproteinases, which are in turn regulated by specific inhibitors. Many of these proteins can be secreted by mesangial cells. In the current study, gene regulation of a rat matrix metalloproteinase, interstitial collagenase and its tissue inhibitor of metalloproteinase-1 (TIMP-1), was investigated by Northern blot analysis. Stimulation of rat mesangial cell (RMC) collagenase by interleukin 1 beta (IL-1 beta) produced an increase (> 45-fold) in mRNA which peaked at 12 h. Lesser effects on the TIMP-1 mRNA expression were observed in response to IL-1 beta. Indomethacin did not influence the effect of IL-1 beta on collagenase, and exogenous prostaglandin E2 had no significant effect either on basal or IL-1 beta-stimulated mRNA levels. Collagenase was secreted into the media and showed minimal gelatinolytic activity at 36-h stimulation with IL-1 beta by zymography. By Western immunoblotting, we demonstrated with 24 h of stimulation the secretion of the active form of collagenase, which further increased after 36 h with IL-1 beta compared with the control. When RMC were retreated with genistein and herbimycin A, both inhibited collagenase mRNA induction by IL-1 beta. These data suggest that IL-1 beta stimulates interstitial collagenase synthesis and activation and that a tyrosine kinase pathway is involved in the signal transduction mechanisms and is not dependent on endogenous prostaglandin biosynthesis. Recently, a third interstitial collagenase (collagenase-3) has been identified from breast carcinoma. This cDNA is 84% identical to the rat interstitial collagenase cDNA probe we have utilized in this study and thus may represent the rat homologue of the human collagenase-3 now called matrix metalloproteinase (MMP)-13.

Animals↗

PubMed1995

Amygdaloid control of alerting and behavioral arousal in rats: involvement of serotonergic mechanisms.

The role of 5-HT mechanisms in the amygdala in the modulation of sleep and arousal states and PGO waves was examined. Studies of the amygdala suggest that it provides a neural mechanism by which emotionally-relevant or significant stimuli may influence behavioral state and alerting mechanisms. The amygdala projects massively (via the central nucleus) into brainstem regions involved in alerting and in the generation of REM and PGO waves. Serotonergic innervation of the amygdala comes from DRN and to a lesser degree MRN. Microinjections of 5-HT into the amygdala produced short-latency changes of state from NREM and REM with the effect being relatively greater in REM. Microinjections of the 5-HT antagonist, methysergide, increased sleep efficiency and increased PGO wave frequency in waking and NREM. These results demonstrate an important role for the amygdala in the control of behavioral state and alerting mechanisms and suggest that 5-HT exerts some of its regulatory effects via an influence on forebrain regions.

Amygdala↗

PubMed1994

Cross-talk between cyclooxygenase and nitric oxide pathways: prostaglandin E2 negatively modulates induction of nitric oxide synthase by interleukin 1.

The inflammatory cytokine interleukin 1 beta (IL-1 beta) induces both cyclooxygenase (COX) and nitric oxide synthase (NOS) with increases in the release of prostaglandin (PG) and nitric oxide (NO) by mesangial cells. Recently, activation of the COX enzyme by NO has been described. However, the effects of COX products (PGs) on the NO pathway have not been fully clarified. Thus we determined the effect of COX inhibition and exogenous PGs on NO production and NOS induction in rat mesangial cells. A COX inhibitor, indomethacin, enhanced IL-1 beta-induced steady-state level of the inducible NOS (iNOS) mRNA and nitrite production. The effect of indomethacin was dose dependently reversed by the replacement of endogenous PGE2 with exogenous PGE2, which is the predominant product of the COX pathway in rat mesangial cells. In contrast to PGE2, a stable analog of PGI2, carba prostacyclin, enhanced IL-1 beta-induced iNOS mRNA levels and nitrite production. Forskolin, an activator of the adenylate cyclase, mimicked the effect of carba prostacyclin but not PGE2. These data suggest that (i) endogenous PGE2 downregulates iNOS induction, (ii) this inhibitory effect of PGE2 on iNOS induction is not mediated by activation of adenylate cyclase, and (iii) exogenous PGI2 stimulates COX induction possibly by activation of adenylate cyclase.

Amino Acid Oxidoreductases↗

PubMed1994

Rapid eye movement sleep disturbance in posttraumatic stress disorder.

The subjective sleep disturbance in posttraumatic stress disorder (PTSD), including the repetitive, stereotypical anxiety dream, suggests dysfunctional rapid eye movement (REM) sleep mechanisms. The polysomnograms of a group of physically healthy combat veterans with current PTSD were compared with those of an age-appropriate normal control group. Tonic and phasic REM sleep measures in the PTSD subjects were elevated on the second night of recorded sleep. Increased phasic REM sleep activity persisted in the PTSD group on the subsequent night. During the study, an anxiety dream occurred in a PTSD subject in REM sleep. The results are consistent with the view that a dysregulation of the REM sleep control system, particularly phasic event generation, may be involved in the pathogenesis of PTSD. The finding of a specific disturbance of sleep unique to PTSD may have significant implications for the design of effective treatments for PTSD.

Adult↗

PubMed1994

Central administration of two 5-HT receptor agonists: effect on REM sleep initiation and PGO waves.

Cholinergic neurons in the pedunculopontine tegmental (PPT) and the laterodorsal tegmental (LDT) nuclei are implicated in the generation of rapid eye movement sleep (REM) and ponto-geniculo-occipital (PGO) waves. Serotonin (5-HT) has a role in sleep-wake regulation and appears to inhibit PGO wave generation. We studied the effects of the central infusion of the relatively specific 5-HT1A receptor agonist 8-hydroxy-2-(n-dipropylamino)tetralin (DPAT) and the less specific 5-HT1 receptor agonist 1(3-chlorophenyl)piperazine (mCPP) on the regulation of REM and on PGO wave generation. DPAT (0.0, 0.002, 0.01, 0.08, and 0.8 microgram/0.5 microliter normal saline) and mCPP (0.0, 0.02, 0.2, 2.0, and 20.0 micrograms/0.5 microliter normal saline) were infused unilaterally into the peribrachial region of PPT (PB) in cats. Additionally, DPAT (0.01 microgram/0.5 microliter) was infused bilaterally into PB in a separate experiment. Low dosages of DPAT (unilateral or bilateral) decreased successful entrances into REM (0.01 microgram) and time spent asleep (0.002 microgram and 0.01 microgram) without affecting outward behavior. No dosage of mCPP significantly decreased the number of REM episodes, and neither drug decreased REM episode duration once REM had been entered. Neither drug affected the rate of PGO waves independently of modulating behavioral state. We propose that 5-HT1A receptor mechanisms have an inhibitory role in actual REM initiation, possibly by facilitating endogenously generated excitation of brainstem startle mechanisms at the onset of REM.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1994

Motor dysfunction during sleep in posttraumatic stress disorder.

A subjective disturbance of sleep, including the occurrence of repetitive, stereotypical anxiety dreams, is characteristic of posttraumatic stress disorder (PTSD). The phenomenology of the PTSD anxiety dream has seemed most consistent with an underlying rapid eye movement (REM) sleep dysfunction. However, motor behavior reportedly can accompany PTSD dreams, and normal REM sleep typically involves a nearly total paralysis of the body musculature. As a means of understanding this discrepancy, anterior tibialis muscle activity during sleep was studied in a group of Vietnam combat veterans with current PTSD and in an age-matched normal control group. The PTSD subjects had a higher percentage of REM sleep epochs with at least one prolonged twitch burst; they also were more likely to have periodic limb movements in sleep, during nonrapid eye movement sleep. Both these forms of muscle activation also have been observed in REM behavior disorder (RBD), a parasomnia characterized by the actual enactment of dream sequences during REM sleep. The identification of RBD-like signs in PTSD adds to the evidence for a fundamental disturbance of REM sleep phasic mechanisms in PTSD.

Electrooculography↗

PubMed1994

Regulation of prostaglandin endoperoxide synthase gene expression in rat mesangial cells by interleukin-1 beta.

In primary cultures of rat mesangial cells from passage 3 to 6, interleukin-1 beta (IL-1) induced a time-dependent increase in prostaglandin E2 (PGE2) formation and release into the extracellular medium. This increase was associated with a dramatic upregulation of the steady-state levels of mRNA for the prostaglandin endoperoxide synthetase (PES)-2 gene transcript as demonstrated by Northern analysis. In contrast, there did not appear to be a significant increase in the mRNA levels for a 2.8-kb transcript for the PES-1 gene. At 18 h of exposure to IL-1, the steady-state level of message for PES-2 remained elevated at 50% of the 2-h time point. Culturing the cells in the presence of cycloheximide and IL-1 demonstrated a superinduction of the PES-2 message without any change in PES-1 message. The tumor-promoting phorbol ester, phorbol myristate acetate (PMA), was also associated with an upregulation of the message for the PES-2 gene and did not influence the levels of the message for the PES-1 gene as demonstrated by Northern analysis. Dexamethasone (Dex) inhibited to control levels the induction by PMA, but the induction of the message by IL-1 was only inhibited 30%. Despite 70% of the message being present by 2 h of induction, Dex was capable of totally inhibiting the inductive effect of IL-1 with respect to PGE2 biosynthesis. Immunocytochemical studies demonstrated a dramatic induction of PES-2 protein by IL-1, which was inhibited by Dex. The data suggest that Dex inhibits the translation of the PES-2 protein.

Animals↗

PubMed1994

IL-1 beta stabilizes COX II mRNA in renal mesangial cells: role of 3'-untranslated region.

We stimulated rat mesangial cells for different time intervals with interleukin-1 beta (IL-1 beta) and phorbol 12-myristate 13-acetate, prepared cytoplasmic extracts, and examined these extracts for the presence of RNA binding proteins by gel mobility shift assays. Here we report that the 3'-untranslated region (3'-UNTR) of the prostaglandin endoperoxide synthase II (COX II) gene is responsible for posttranscriptional regulation of the response to IL-1 beta. Two cytosolic transacting factors of 65 and 45 kDa, respectively, have been detected that bind to the 3'-UNTR. Competition with excess RNA and acid phosphatase treatment of the cytoplasmic extract suggest the binding is specific and that phosphorylation is required for these rapid binding events. These experiments suggest that IL-1 beta induces the phosphorylation of cytosolic factors, which bind to the 3'-UNTR of COX II mRNA, and stabilizes the message.

Acid Phosphatase↗