Induction of cyclin A gene expression by homocysteine in vascular smooth muscle cells

Homocysteine is an important and independent risk factor for arteriosclerosis. We showed previously that homocysteine stimulates vascular smooth muscle cell proliferation, a hallmark of arteriosclerosis. We show here that homocysteine and serum increased DNA synthesis synergistically in both human and rat aortic smooth muscle cells (RASMCs). Treatment of quiescent RASMCs with 1 mM homocysteine or 2% calf serum for 36 h increased cyclin A mRNA levels by 8- and 14-fold, respectively, whereas homocysteine plus serum increased cyclin A mRNA levels by 40-fold, indicating a synergistic induction of cyclin A mRNA. Homocysteine did not increase the half-life of cyclin A mRNA (2.9 h), but it did increase the transcriptional rate of the cyclin A gene in nuclear run-on experiments. The positive effect of homocysteine on cyclin A gene transcription was confirmed by our finding that homocysteine increased cyclin A promoter activity and ATF-binding protein levels in RASMCs. Finally, 1 mM homocysteine increased cyclin A protein levels and cyclin A-associated kinase activity by threefold. This homocysteine-induced expression lesions by promoting proliferation of vascular smooth muscle cells.

Adrenomedullin stimulates calcium efflux from adrenal chromaffin cells in culture: possible involvement of an Na+/Ca2+ exchange mechanism

The effect of adrenomedullin, a hypotensive peptide, on Ca2+ efflux from cultured bovine adrenal chromaffin cells was examined. Adrenomedullin stimulated the efflux of 45Ca2+ from the cells in a concentration-dependent manner (10(-7)M - 3x10(-6)M). Adrenomedullin did not increase the intracellular free Ca2+ ([Ca2+]i) level and catecholamine secretion. The adrenomedullin-stimulated 45Ca2+ efflux was not inhibited by incubation with Ca2+-free medium, but was inhibited by incubation with Na+-free medium. These results indicate that adrenomedullin stimulates extracellular Na+-dependent 45Ca2+ efflux from cultured bovine adrenal chromaffin cells, probably through its stimulatory effect on membrane Na+/Ca2+ exchange.

Regulatory mechanism of calcium efflux from cultured bovine adrenal chromaffin cells induced by extracellular ATP

The effect of adenosine-5'-triphosphate (ATP) on Ca2+ efflux from cultured bovine adrenal chromaffin cells was examined. ATP stimulated the efflux of 45Ca2+ from the cells in a concentration-dependent manner (0.01-1 mM). The 45Ca2+ efflux from the cells was also stimulated by adenosine-5'-O-(3-thiotriphosphate) (ATP-gamma s), alpha beta-methylene-ATP and adenosine-5'-diphosphate (ADP), but was not by adenosine-5'-monophosphate (AMP) and adenosine. The ATP-stimulated 45Ca2+ efflux was not affected by deprivation of the extracellular Ca2+ and Mg2+, but was dependent on the extracellular Na+ concentrations. ATP increased the influx of 22Na+ into the cells. These results indicate that ATP stimulates extracellular Na(+)-dependent 45Ca2+ efflux from cultured bovine adrenal chromaffin cells, probably through its stimulatory effect on membrane Na+/Ca2+ exchange.

Cloning and functional analysis of the promoter for KDR/flk-1, a receptor for vascular endothelial growth factor

KDR/flk-1 is one of two receptors for vascular endothelial growth factor, a potent angiogenic peptide. KDR/flk-1 is an early marker for endothelial cell progenitors, and its expression is restricted to endothelial cells in vivo. To investigate the molecular mechanisms regulating expression of KDR/flk-1, we cloned and characterized the promoter of the human KDR/flk-1 gene. The transcription start site was localized by primer extension and ribonuclease protection to a nucleotide 303 base pairs (bp) 5' of the initiation methionine codon. The 5'-flanking sequence is rich in G and C residues and contains five Sp1 elements but no TATA consensus sequence. By reporter gene transfection experiments, we found that approximately 4 kilobases of KDR/flk-1 5'-flanking sequence directed high level luciferase activity in bovine aortic endothelial cells; further deletion analysis revealed positive regulatory elements between bp -225 to -164, -95 to -77, -77 to -60, and +105 to +127. Mutation of an atypical GATA sequence between bp +105 and +127 did not affect promoter activity, suggesting that GATA elements are not essential for the high level promoter activity of this gene. Consistent with endothelial cell-restricted expression of KDR/flk-1 mRNA, we found that the 4-kilobase flanking sequence directed high level promoter activity in endothelial cells but not in other cell types. To our knowledge this is the first report characterizing the KDR/flk-1 promoter. Understanding the KDR/flk-1 promoter will allow us to investigate endothelial cell-specific gene regulation and to uncover methods for targeting gene delivery specifically to endothelial cells.

Lysophosphatidic acid as a stimulator of Na(+)-dependent Ca2+ efflux from adrenal chromaffin cells

The effect of lysophosphatidic acid (LPA) on Ca2+ efflux from cultured bovine adrenal chromaffin cells was examined. LPA stimulated the efflux of 45Ca2+ from the cells in a concentration dependent manner (10(-7)-10(-5)M). Other lysophospholipids (lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylinositol and lysophosphatidylserine), phosphatidic acid, monoolein and oleic acid had not significant effect on 45Ca2+ efflux from the cells. The LPA-stimulated 45Ca2+ efflux was dependent on the extracellular Na+ concentration and was inhibited by amiloride, inhibitor of Na+/Ca2+ exchange. LPA increased 22Na+ uptake into the cells and this effect was also sensitive to amiloride. These results indicate that LPA stimulates extracellular Na(+)-dependent 45Ca2+ efflux from cultured bovine adrenal chromaffin cells, probably through its stimulatory effect on membrane Na+/Ca2+ exchange.

Potentiation by ouabain of bradykinin-induced catecholamine secretion and calcium influx into cultured bovine adrenal chromaffin cells: evidence for involvement of Na+ influx associated with the bradykinin B2-receptor

The effect of bradykinin (BK), in the presence of ouabain, an inhibitor of Na(+)-K+ ATPase, on catecholamine (CA) secretion was studied in cultured bovine adrenal chromaffin cells, to determine whether Na+, as well as Ca2+, is involved in BK-receptor mediated CA secretion. BK (10(-8)-10(-5) M)-induced CA secretion was markedly potentiated by addition of ouabain (10(-5) M), was blocked by a BK-B2 receptor antagonist, and was decreased in Ca(2+)-free medium. BK-induced increase in 45Ca2+ influx was also potentiated by addition of ouabain. The cultured cells were first incubated with BK for 30 min in Ca(2+)-free medium in the presence or absence of ouabain and then stimulated for 15 min with Ca(2+)-medium without BK or ouabain. Prior stimulation of the cells, BK induced 22Na+ influx and increased Ca(2+)-induced CA secretion and these stimulatory effects of BK were potentiated by added ouabain. When the cells were stimulated with BK and ouabain in Na(+)-free sucrose medium, the Ca(2+)-induced CA secretion was greatly reduced. These results indicated that activation of the BK-B2 receptor and inhibition of the Na+ pump both increase the intracellular Na+ level, resulting in increase in Ca2+ influx and CA secretion.

Physiological significance of plasma sulfoconjugated dopamine: experimental and clinical studies

Sulfoconjugated catecholamines have been regarded simply as metabolites of free catecholamines. However, a conjugated form of the catecholamine, dopamine has recently attracted much attention because it is present at high levels in the plasma of humans and experimental animals. We carried out experimental and clinical studies to determine the physiological significance of this large amount of dopamine conjugate in the plasma. Clinical studies showed that the plasma level of dopamine sulfate decreased significantly during the acute phase of heart failure, whereas that of free dopamine increased. Moreover, the plasma level of conjugated dopamine in patients with essential hypertension was higher than that in control subjects, and being highest in patients with renal hypertension. In experimental studies, we examined the activity for deconjugating DA sulfate in homogenates of organs from dogs. The kidney and liver exhibited the highest activities, and in the heart, the activity was higher in the atrium than the ventricle. We also examined the effect of dopamine sulfate on isolated perfused rat heart. Dopamine sulfate was found to be converted to free dopamine, which was responsible for the positive inotropic action, in atrial tissue. Moreover, deconjugation of DA sulfate to the free form was accelerated by a high work lord on the heart. From these results, we conclude that the formation of dopamine sulfate plays a role in regulating the level of plasma free dopamine and that plasma dopamine sulfate may be a storage or reserve form of dopamine. Free (or active) dopamine may be formed through a deconjugation reaction when necessary.

The ATF site mediates downregulation of the cyclin A gene during contact inhibition in vascular endothelial cells

Contact inhibition mediates monolayer formation and withdrawal from the cell cycle in vascular endothelial cells. In studying the cyclins--key regulators of the cell cycle--in bovine aortic endothelial cells (BAEC), we found that levels of cyclin A mRNA decreased in confluent BAEC despite the presence of 10% fetal calf serum. We then transfected into BAEC a series of plasmids containing various lengths of the human cyclin A 5' flanking sequence and the luciferase gene. Plasmids containing 3,200, 516, 406, 266, or 133 bp of the human cyclin A promoter directed high luciferase activity in growing but not confluent BAEC. In contrast, a plasmid containing 23 bp of the cyclin A promoter was associated with a 65-fold reduction in activity in growing BAEC, and the promoter activities of this plasmid were identical in both growing and confluent BAEC. Mutation of the activating transcription factor (ATF) consensus sequence at bp -80 to -73 of the cyclin A promoter decreased its activity, indicating the critical role of the ATF site. We identified by gel mobility shift analysis protein complexes that bound to the ATF site in nuclear extracts from growing but not confluent BAEC and identified (with antibodies) ATF-1 as a binding protein in nuclear extracts from growing cells. Also, ATF-1 mRNA levels decreased in confluent BAEC. Taken together, these data suggest that the ATF site and its cognate binding proteins play an important role in the downregulation of cyclin A gene expression during contact inhibition.

Disappearance of cyclin A correlates with permanent withdrawal of cardiomyocytes from the cell cycle in human and rat hearts

The regulated expression of cyclins controls the cell cycle. Because cardiomyocytes in adult mammals withdraw permanently from the cell cycle and thus cannot regenerate after injury, we examined cyclin expression during development by comparing cyclin A-E mRNA levels in fetal and adult human hearts. Cyclin B mRNA was detectable in adult hearts, although at a level markedly lower than that in fetal hearts. Levels of cyclin C, D1, D2, D3, and E mRNA were essentially identical in the two groups. In contrast, cyclin A mRNA was undetectable in adult hearts whereas cyclin A mRNA and protein were readily detectable in fetal hearts and cardiomyocytes, respectively. We then measured cyclin A mRNA and protein levels in rat hearts at four stages of development (fetal and 2, 14, and 28 d). Cyclin A mRNA and protein levels decreased quickly after birth (to 37% at day 2) and became undetectable within 14 d, an observation consistent with reports that cardiomyocytes stop replicating in rats by the second to third postnatal week. This disappearance of cyclin A gene expression in human and rat hearts at the time cardiomyocytes become terminally differentiated suggests that cyclin A downregulation is important in the permanent withdrawal of cardiomyocytes from the cell cycle.

The forms and the levels of fecal PMN-elastase in patients with colorectal diseases

OBJECTIVES

To compare the form of polymorphonuclear leukocyte (PMN)-elastase in feces with that in plasma and to investigate the usefulness of measuring fecal PMN-elastase levels in patients with colorectal diseases.

METHODS

We examined PMN-elastase complexed with alpha 1-antitrypsin (alpha 1-AT), chymotrypsin, and alpha 2-macroglobulin by ELISA in feces and plasma. Fecal levels of total PMN-elastase were determined in patients with colonic polyp (N = 19), colonic cancer (N = 20), ulcerative colitis (UC; N = 36), colonic Crohn's disease (CD; N = 26), and in control subjects (N = 20).

RESULTS

Most PMN-elastase was not complexed with alpha 1-AT, chymotrypsin, or alpha 2-macroglobulin in feces, whereas most plasma PMN-elastase was complexed with alpha 1-AT. Fecal concentrations and daily fecal excretion of PMN-elastase were significantly increased in patients with active UC (medians 54.8 micrograms/g, 15.14 mg/day) and active CD (41.5 micrograms/g, 10.24 mg/day) compared to those values in control subjects (0.6 micrograms/g, 0.11 mg/day) and in patients with colonic cancer (2.5 micrograms/g, 0.33 mg/day). In inactive UC and CD, these values (3.4 micrograms/g, 0.52 mg/day and 5.2 micrograms/g, 0.59 mg/day, respectively) were significantly lower than in active UC and CD, respectively. In UC, all patients whose rectal biopsies showed infiltration of PMN had high fecal PMN-elastase levels.

CONCLUSIONS

Our results suggest that the measurement of fecal PMN-elastase concentrations are useful for monitoring the disease activity of UC and CD, especially when evaluating whether intestinal inflammation has disappeared completely.

Induction of vascular endothelial growth factor gene expression by interleukin-1 beta in rat aortic smooth muscle cells

Vascular endothelial growth factor (VEGF) is a potent and specific mitogen for vascular endothelial cells and promotes neovascularization in vivo. To determine whether interleukin-1 beta (IL-1 beta), which is present in atherosclerotic lesions, induces VEGF gene expression in vascular smooth muscle cells, we performed RNA blot analysis on rat aortic smooth muscle cells (RASMC) with a rat VEGF cDNA probe. IL-1 beta increased VEGF mRNA levels in RASMC in a time- and dose-dependent manner. As little as 0.1 ng/ml IL-1 beta increased VEGF mRNA levels by 2-fold and 10 ng/ml IL-1 beta increased VEGF mRNA by 4-fold. We also measured the half-life of VEGF mRNA and performed nuclear run-on experiments before and after addition of IL-1 beta to see if IL-1 beta increased VEGF mRNA levels by stabilizing the mRNA or by increasing its rate of transcription. The normal, 2-h half-life of VEGF mRNA in RASMC was lengthened to 3.2 h (60%) by IL-1 beta, and IL-1 beta increased the rate of VEGF gene transcription by 2.1-fold. In immunoblot experiments with an antibody specific for VEGF, we found that IL-1 beta increased VEGF protein levels in RASMC by 3.3-fold. Together these data indicate that IL-1 beta induces VEGF gene expression in smooth muscle cells. This IL-1 beta-induced expression of VEGF may accelerate the progression of atherosclerotic lesions by promoting the development of new blood vessels.

Regulation of heparin-binding epidermal growth factor-like growth factor mRNA levels by hypertrophic stimuli in neonatal and adult rat cardiac myocytes

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a recently characterized member of the EGF family of peptide signaling factors that acts as an early response gene to growth stimuli in vascular smooth muscle cells, as well as being a potent mitogen for these cells. As many of these growth stimuli also induce a hypertrophic response in heart muscle, we examined the regulation of HB-EGF mRNA abundance and function in primary cultures of neonatal rat ventricular myocytes and adult rat ventricular myocytes (ARVM). HB-EGF mRNA levels increased 40- and 6-fold in neonatal rat ventricular myocytes and ARVM, respectively, following a 2-4-h exposure to the alpha-adrenergic agonist phenylephrine, a known hypertrophic stimulus for these cells. Phenylephrine had no effect on HB-EGF mRNA stability, and induction of HB-EGF could be blocked completely by actinomycin D. HB-EGF mRNA abundance was also increased 15-fold in ARVM maintained in defined medium that had been induced to contract at 3 Hz by continual uniform electric field stimulation, a mechanical stimulus that we have shown preserves contractile function and induces cell growth in vitro. To determine whether cardiac myocytes would respond to exogenous HB-EGF, quiescent ARVM were exposed to defined medium conditioned by transfected COS MT cells overexpressing HB-EGF. These myocytes exhibited nearly a 2-fold increase in protein content at 24 h compared with unstimulated control ARVM exposed to medium conditioned by COS cells transfected with the plasmid vector alone. Thus, neonatal and adult cardiac muscle cells respond to both neurohumoral and mechanical growth stimuli with a marked increase in HB-EGF mRNA, which may act as an early response gene to facilitate hypertrophic growth in these cells.

Role of Ca2+ and protein kinase C in shear stress-induced actin depolymerization and endothelin 1 gene expression

Vascular endothelial cells adapt to changes in blood flow by altering the cell architecture and by producing various substances. We have previously reported that low shear stress induces endothelin 1 (ET-1) expression in endothelial cells and that this induction is mediated by depolymerization of actin fiber. In the present study, we examined the role of Ca2+ and protein kinase C (PKC) in shear stress-induced actin depolymerization and subsequent ET-1 gene expression. Exposure of cultured porcine aortic endothelial cells to low shear stress (5 dyne/cm2) for 3 hours increased the ratio of G-actin to total actin from 54 +/- 0.8% to 80 +/- 1.0%. This shear stress-induced actin depolymerization was completely blocked by chelation of extracellular Ca2+ with EGTA and partially inhibited by intracellular Ca2+ chelation with the tetraacetoxymethyl ester of BAPTA (BAPTA/AM). Pretreatment with staurosporine, a PKC inhibitor, or desensitization of PKC by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) for 24 hours also resulted in partial inhibition of shear stress-induced actin depolymerization. Although PKC activation by TPA mildly increased G-actin content, the effect of TPA and shear stress on actin depolymerization was not additive. Moreover, shear stress-induced ET-1 gene expression was inhibited by EGTA, BAPTA/AM, and staurosporine to a degree similar to the inhibition of actin depolymerization. In contrast, ET-1 gene expression induced by cytochalasin B, an actin-disrupting agent, was not affected by staurosporine.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative evaluation of intraarterial lymphocyte injection therapy for lymph edema using MR imaging

Five patients with unilateral leg lymph edema had intraarterial injections of lymphocytes in the affected leg with consequent improvement in 3. To assess the degree of lymph edema, T2 and intensity ratio between the 2 legs in STIR images were used. Mean and SD of T2 values in the subcutaneous tissue were measured using a triple echo sequence and found larger on the edematous side than in the opposite extremity. The mean T2 shortening obtained after the lymphocyte therapy correlated well with the reduction of limb circumference. Mean T2 reflects the fluid content, and SD of T2 the fluid distribution in the subcutaneous tissue. The degree of lymph edema and the effect of therapy can be evaluated quantitatively by measuring the value of the T2 relaxation time.

Inhibition by ouabain of palytoxin-induced catecholamine secretion and calcium influx into cultured bovine adrenal chromaffin cells

The effect of ouabain on palytoxin (PTX)-induced catecholamine secretion from cultured bovine adrenal chromaffin cells was examined in relation to its effect on calcium (Ca2+) influx into the cells. Ouabain showed concentration-dependent inhibition of catecholamine secretion induced by PTX. Ouabain also inhibited [45Ca]2+ influx induced by PTX, this inhibition being parallel with that of catecholamine secretion. The inhibitory effects of ouabain on PTX-induced catecholamine secretion and [45Ca]2+ influx were both overcome by increasing the concentrations of PTX, indicating that ouabain inhibited the actions of PTX in a competitive manner. These results suggest that the ouabain-sensitive (or-binding) site on the cell membrane might be the target site of action of PTX, which causes an increase in Ca2+ permeability and initiation of catecholamine secretion.

Promotion of vascular smooth muscle cell growth by homocysteine: a link to atherosclerosis

Plasma homocysteine levels are elevated in 20-30% of all patients with premature atherosclerosis. Although elevated homocysteine levels have been recognized as an independent risk factor for myocardial infarction and stroke, the mechanism by which these elevated levels cause atherosclerosis is unknown. To understand the role of homocysteine in the pathogenesis of atherosclerosis, we examined the effect of homocysteine on the growth of both vascular smooth muscle cells and endothelial cells at concentrations similar to those observed in clinical studies. As little as 0.1 mM homocysteine caused a 25% increase in DNA synthesis, and homocysteine at 1 mM increased DNA synthesis by 4.5-fold in rat aortic smooth muscle cells (RASMC). In contrast, homocysteine caused a dose-dependent decrease in DNA synthesis in human umbilical vein endothelial cells. Homocysteine increased mRNA levels of cyclin D1 and cyclin A in RASMC by 3- and 15-fold, respectively, indicating that homocysteine induced the mRNA of cyclins important for the reentry of quiescent RASMC into the cell cycle. Furthermore, homocysteine promoted proliferation of quiescent RASMC, an effect markedly amplified by 2% serum. The growth-promoting effect of homocysteine on vascular smooth muscle cells, together with its inhibitory effect on endothelial cell growth, represents an important mechanism to explain homocysteine-induced atherosclerosis.

Transforming growth factor-beta 1, but not dexamethasone, down-regulates nitric-oxide synthase mRNA after its induction by interleukin-1 beta in rat smooth muscle cells

Nitric oxide (NO), which accounts for the biologic properties of endothelium-derived relaxing factor, is synthesized from L-arginine by nitric-oxide synthase (NOS). Two classes of NOS have been identified: a constitutive, calcium-dependent isozyme (cNOS) and an inducible, calcium-independent isozyme (iNOS). NO is generated after the induction of iNOS by cytokines such as interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha. As a potent vasodilator, NO may have an important role in the severe hypotension of septic shock. We investigated whether dexamethasone and transforming growth factor-beta 1 (TGF-beta 1) suppress iNOS mRNA after its induction by IL-1 beta. We found that IL-1 beta induced iNOS mRNA in rat aortic smooth muscle cells (RASMC) in a dose- and time-dependent fashion. IL-1 beta promoted a dramatic and prolonged induction of RASMC iNOS mRNA that peaked at 48 h. Dexamethasone prevented this induction of iNOS mRNA only when given before the addition of IL-1 beta. In contrast, TGF-beta 1 inhibited the induction of iNOS mRNA and NO production in RASMC both before and after the addition of IL-1 beta. After 24 h of IL-1 beta stimulation, TGF-beta 1 down-regulated the iNOS mRNA that had been induced during this initial time period. In nuclear run-on experiments, we found that the down-regulation of iNOS mRNA by TGF-beta 1 in RASMC occurred at the transcriptional level. Our observation that TGF-beta 1 mediates inhibition of RASMC iNOS mRNA after its induction by cytokines may be an important insight into the treatment of septic shock.

Effects of the potassium channel openers cromakalim and pinacidil on catecholamine secretion and calcium mobilization in cultured bovine adrenal chromaffin cells

The effects of two K+ channel openers, cromakalim and pinacidil, on voltage-dependent and receptor-mediated catecholamine secretion and Ca2+ mobilization in bovine adrenal chromaffin cells were studied to determine the role of membrane K+ channels in the regulation of a Ca(2+)-dependent secretory process. Both cromakalim and pinacidil stimulated the efflux of 86Rb (used to monitor K+ permeability) from preloaded cells. Cromakalim and pinacidil did not affect the catecholamine secretion induced by excessive depolarization with 56 mM K+, but inhibited that induced by moderate depolarization with 31 mM K+ in a concentration-dependent manner (1 microM-100 microM). The 31 mM K(+)-induced 45Ca2+ influx and increase in intracellular free Ca2+ concentration [Ca2+]i were also inhibited by these agents at similar concentrations to those for inhibition of catecholamine secretion. Cromakalim and pinacidil inhibited catecholamine secretion, 45Ca2+ influx and increase in [Ca2+]i induced by stimulation of nicotinic acetylcholine (ACh) receptors with carbamylcholine. Furthermore, both cromakalim and pinacidil inhibited the increase in [Ca2+]i induced by carbamylcholine in the absence of extracellular Ca2+, which is thought to be mediated by muscarinic ACh receptors. On the other hand, they did not affect catecholamine secretion induced by Bay-K 8644, Ba2+, A23187, histamine or bradykinin. These results indicate that the K+ channel openers, cromakalim and pinacidil, selectively inhibit catecholamine secretion induced by moderate depolarization or by nicotinic ACh receptor stimulation by inhibiting Ca2+ influx and increase in [Ca2+]i. Furthermore, the results suggest that these K+ channel openers-sensitive membrane K+ channels are involved in the regulation of catecholamine secretion mainly indirectly through effects on the voltage-dependent membrane Ca2+ channels.

Estradiol-17 beta regulates the induction of VCAM-1 mRNA expression by interleukin-1 beta in human umbilical vein endothelial cells

We examined the effect of estradiol-17 beta on the expression of vascular cell adhesion molecule-1 (VCAM-1), an adhesion molecule, in human umbilical vascular endothelial cells. After preincubation with estradiol-17 beta for 24 hours, cells were treated for 4 h with 0.5 micrograms/ml recombinant human interleukin-1 beta. The RNase protection assay was performed using an [alpha-32P]-labeled 121 base pair VCAM-1 cRNA probe. Preincubation with estradiol-17 beta (250 or 500 pg/ml) suppressed the induction of VCAM-1 mRNA expression by interleukin-1 beta. VCAM-1 staining with a monoclonal antibody decreased when cells were incubated with estradiol-17 beta at 250 and 500 pg/ml, while staining was detectable when cells were treated with interleukin-1 beta at 0.5 micrograms/ml. In conclusion, estradiol-17 beta regulates the induction of VCAM-1 gene expression by interleukin-1 beta in human umbilical vein endothelial cells.

Shear stress increases heparin-binding epidermal growth factor-like growth factor mRNA levels in human vascular endothelial cells

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a recently identified potent vascular smooth muscle cell (SMC) mitogen. We investigated the effect of shear stress on human HB-EGF mRNA levels in cultured human umbilical vein endothelial cells (HUVEC). In response to shear stress (8 dyne/cm2), HB-EGF mRNA levels in HUVEC increased rapidly, peaked at 3 h, and returned to near base line at 7 h. The shear stress-induced HB-EGF gene expression in HUVEC is completely blocked by 12-O-tetra-decanoylphorbol-13-acetate pre-treatment, suggesting the induction of HB-EGF is mediated by protein kinase C.