Role of ROCK2 in CD4+ cells in allergic airways responses in mice.

BACKGROUND: Rho kinases (ROCKs) contribute to allergic airways disease. ROCKs also play a role in lymphocyte proliferation and migration. OBJECTIVE: To determine the role of ROCK2 acting within CD4+ cells in allergic airways responses. METHODS: ROCK2-haploinsufficient (ROCK2+/- ) and wild-type mice were sensitized with ovalbumin (OVA). ROCK2+/- mice then received either CD4+ cells from ROCK2-sufficient OVA TCR transgenic (OT-II) mice or saline i.v. 48 h before challenge with aerosolized OVA. Wild-type mice received saline before challenge. Allergic airways responses were measured 48 h after the last challenge. Allergic airways responses were also assessed in mice lacking ROCK2 only in CD4+ cells (ROCK2CD4Cre mice) vs. control (CD4-Cre and ROCK2flox/flox ) mice. RESULTS: OVA-induced increases in bronchoalveolar lavage lymphocytes, eosinophils, IL-13, IL-5, and eotaxin were reduced in ROCK2+/- vs. wild-type mice, as were airway hyperresponsiveness and mucous hypersecretion. In ROCK2+/- mice, adoptive transfer with CD4+ cells from OT-II mice restored effects of OVA on lymphocytes, eosinophils, IL-13, IL-5, and mucous hypersecretion to wild-type levels, whereas eotaxin and airway hyperresponsiveness were not affected. ROCK2 inhibitors reduced IL-13-induced release of eotaxin from airway smooth muscle (ASM), similar to effects of these inhibitors on ASM contractility. Despite the ability of adoptive transfer to restore allergic airways inflammation in ROCK2-insufficient mice, allergic inflammation was not different in ROCK2CD4Cre vs. control mice. CONCLUSION: ROCK2 contributes to allergic airways responses likely via effects within ASM cells and within non-lymphocyte cells involved in lymphocyte activation and migration into the airways.

ROCK1 & 2 perform overlapping and unique roles in angiogenesis and angiosarcoma tumor progression.

The serine/threonine protein kinase paralogs ROCK1 & 2 have been implicated as essential modulators of angiogenesis; however their paralog-specific roles in endothelial function are unknown. shRNA knockdown of ROCK1 or 2 in endothelial cells resulted in a significant disruption of in vitro capillary network formation, cell polarization, and cell migration compared to cells harboring non-targeting control shRNA plasmids. Knockdowns led to alterations in cytoskeletal dynamics due to ROCK1 & 2-mediated reductions in actin isoform expression, and ROCK2-specific reduction in myosin phosphatase and cofilin phosphorylation. Knockdowns enhanced cell survival and led to ROCK1 & 2-mediated reduction in caspase 6 and 9 cleavage, and a ROCK2-specific reduction in caspase 3 cleavage. Microarray analysis of ROCK knockdown lines revealed overlapping and unique control of global transcription by the paralogs, and a reduction in the transcriptional regulation of just under 50% of VEGF responsive genes. Finally, paralog knockdown in xenograft angiosarcoma tumors resulted in a significant reduction in tumor formation. Our data reveals that ROCK1 & 2 exhibit overlapping and unique roles in normal and dysfunctional endothelial cells, that alterations in cytoskeletal dynamics are capable of overriding mitogen activated transcription, and that therapeutic targeting of ROCK signaling may have profound impacts for targeting angiogenesis.

Mineralocorticoid receptor blocker eplerenone improves endothelial function and inhibits Rho-associated kinase activity in patients with hypertension.

Hypertension is associated with endothelial dysfunction and activated Rho-associated kinases (ROCKs). The purpose of this study was to evaluate the effects of the selective mineralocorticoid receptor blocker, eplerenone, on endothelial function and ROCK activity in patients with hypertension. The study was carried out over 48 weeks in 60 untreated patients with hypertension who were randomly assigned to eplerenone, nifedipine, and losartan groups. We evaluated the effects of each treatment on flow-mediated vasodilation (FMD) and ROCK activity in peripheral leukocytes. Eplerenone increased FMD and decreased leukocyte ROCK activity. Nifedipine decreased ROCK activity but did not alter FMD. Losartan increased FMD but did not alter ROCK activity. Hypotensive effects were similar in the three groups, as was nitroglycerin-induced vasodilation during the follow-up period. There were no significant differences between the groups with respect to other parameters. The study results show that eplerenone improves endothelial function and inhibits ROCK activity in patients with essential hypertension.

Role of Rho kinase isoforms in murine allergic airway responses.

Inhibition of Rho-associated coiled-coil forming kinases (ROCKs) reduces allergic airway responses in mice. The purpose of this study was to determine the roles of the two ROCK isoforms, ROCK1 and ROCK2, in these responses. Wildtype (WT) mice and heterozygous ROCK1 and ROCK2 knockout mice (ROCK1(+/-) and ROCK2(+/-), respectively) were sensitised and challenged with ovalbumin. ROCK expression and activation were assessed by western blotting. Airway responsiveness was measured by forced oscillation. Bronchoalveolar lavage was performed and the lungs were fixed for histological assessment. Compared with WT mice, ROCK1 and ROCK2 expression were 50% lower in lungs of ROCK1(+/-) and ROCK2(+/-) mice, respectively, without changes in the other isoform. In WT lungs, ROCK activation increased after ovalbumin challenge and was sustained for several hours. This activation was reduced in ROCK1(+/-) and ROCK2(+/-) lungs. Airway responsiveness was comparable in WT, ROCK1(+/-), and ROCK2(+/-) mice challenged with PBS. Ovalbumin challenge caused airway hyperresponsiveness in WT, but not ROCK1(+/-) or ROCK2(+/-) mice. Lavage eosinophils and goblet cell hyperplasia were significantly reduced in ovalbumin-challenged ROCK1(+/-) and ROCK2(+/-) versus WT mice. Ovalbumin-induced changes in lavage interleukin-13, interleukin-5 and lymphocytes were also reduced in ROCK1(+/-) mice. In conclusion, both ROCK1 and ROCK2 are important in regulating allergic airway responses.

Simvastatin decreases IL-6 and IL-8 production in epithelial cells.

Many cardiovascular studies have suggested that 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors (statins) have anti-inflammatory effects independent of cholesterol lowering. As a chronic inflammatory disease, periodontitis shares some mechanisms with atherosclerosis. Since oral epithelial cells participate importantly in periodontal inflammation, we measured simvastatin effects on interleukin-6 and interleukin-8 production by cultured human epithelial cell line (KB cells) in response to interleukin-1alpha. Simvastatin decreased production, an effect reversed by adding mevalonate or geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. Simvastatin was found to reduce NF-kappaB and AP-1 promoter activity in KB cells. Dominant-negative Rac1 severely inhibited interleukin-1alpha-induced NF-kappaB and AP-1 promoter activity. Our results may indicate an anti-inflammatory effect of simvastatin on human oral epithelial cells, apparently involving Rac1 GTPase inhibition.

Lipid management with statins. The lower the better?

The primary and not yet accomplished goal remains to treat all patients with coronary heart disease to the LDL cholesterol target < 100 mg/dl. To date there is no conclusive evidence for a recommendation of a LDL cholesterol goal lower than 100 mg/dl for all patients. Patients with high vascular risk benefit from statin therapy irrespective of cholesterol levels, underlining the importance of the assessment of global vascular risk as the basis of modern lipid therapy.

Statins: potent vascular anti-inflammatory agents.

Atherosclerosis is a multifactorial condition that can result in cardiovascular disease. Statin therapy is thought to mediate cardioprotective effects that influence endothelial function, inflammatory responses, plaque stability and thrombus formation, processes involved in atherosclerosis. Although reduction in low-density lipoprotein cholesterol (LDL-C) potentially plays a role in all of these effects, several lines of evidence also implicate nonlipidmediated 'pleiotropic' effects. For example, statin therapy confers a lower risk for coronary heart disease than placebo in patients with comparable serum cholesterol levels, and confers a greater magnitude of clinical benefit than expected based on LDL-C levels alone. Moreover, while nonstatin lipid-lowering therapy does not necessarily reduce stroke risk, statins have shown a significant reduction in stroke. Statins exert their pleiotropic effects, in part, by improving endothelial function via up-regulation of endothelial nitric oxide synthase enzyme activity. Markers of inflammation such as high sensitivity C-reactive protein have been also shown to add further prognostic information about patients at risk of cardiovascular disease who may benefit from statin therapy. Further studies are still needed to determine whether statins have direct effects on inflammatory pathways.

Cross-coupling between the oestrogen receptor and phosphoinositide 3-kinase.

Gender differences in cardiovascular mortality are well documented and oestrogen replacement therapy in post-menopausal women is associated with improved outcomes from cardiovascular events. Indeed, oestrogen therapy has been shown to restore endothelial function in post-menopausal women and reduce the development of atherosclerotic lesions. Despite extensive evidence on the beneficial effect of oestrogen, relatively little is known regarding the molecular signalling mechanism(s) by which oestrogen exerts some of its vascular effects. While the nuclear function of the oestrogen receptor is clearly established, previous studies regarding the membrane and cytoplasmic actions of oestrogen remain inconclusive. Cross-coupling of the oestrogen receptor to phosphoinositide 3-kinase signalling suggests a potentially critical non-nuclear action of the oestrogen receptor and considerably broadens our understanding of the cellular effects of oestrogen.

Salicylates and vascular smooth muscle cell proliferation: molecular mechanisms for cell cycle arrest.

Salicylates are effective prophylactic treatment strategies for myocardial infarction and ischemic strokes. Recent evidence suggests that high doses of salicylates may exert direct, platelet-independent effects on the vascular wall. Salicylate and aspirin, in concentrations between 1 and 5 mM, effectively inhibit vascular smooth muscle cell proliferation and DNA synthesis without inducing cellular toxicity or apoptosis. This inhibition is associated with effects on specific cell-cycle regulatory molecules, and may proceed via downregulation of the transcription factor, nuclear factor (NF)-kappaB. High-dose salicylates and selective NF-kappaB inhibitors may, therefore, play an important role in the management of vascular proliferative disorders.

Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors.

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors or statins are potent inhibitors of cholesterol biosynthesis. Several large clinical trials have demonstrated the beneficial effects of statins in the primary and secondary prevention of coronary heart disease. However, the overall clinical benefits observed with statin therapy appear to be greater than what might be expected from changes in lipid profile alone, suggesting that the beneficial effects of statins may extend beyond their effects on serum cholesterol levels. Indeed, recent experimental and clinical evidence indicates that some of the cholesterol-independent or "pleiotropic" effects of statins involve improving or restoring endothelial function, enhancing the stability of atherosclerotic plaques, and decreasing oxidative stress and vascular inflammation. Many of these pleiotropic effects of statins are mediated by their ability to block the synthesis of important isoprenoid intermediates, which serve as lipid attachments for a variety of intracellular signaling molecules. In particular, the inhibition of small GTP-binding proteins, Rho, Ras, and Rac, whose proper membrane localization and function are dependent on isoprenylation, may play an important role in mediating the direct cellular effects of statins on the vascular wall.

Statins as antioxidant therapy for preventing cardiac myocyte hypertrophy.

Cardiac hypertrophy is a major cause of morbidity and mortality worldwide. The hypertrophic process is mediated, in part, by small G proteins of the Rho family. We hypothesized that statins, inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, inhibit cardiac hypertrophy by blocking Rho isoprenylation. We treated neonatal rat cardiac myocytes with angiotensin II (AngII) with and without simvastatin (Sim) and found that Sim decreased AngII-induced protein content, [3H] leucine uptake, and atrial natriuretic factor (ANF) promoter activity. These effects were associated with decreases in cell size, membrane Rho activity, superoxide anion (O2*-) production, and intracellular oxidation, and were reversed with L-mevalonate or geranylgeranylpyrophosphate, but not with farnesylpyrophosphate or cholesterol. Treatments with the Rho inhibitor C3 exotoxin and with cell-permeable superoxide dismutase also decreased AngII-induced O2*- production and myocyte hypertrophy. Overexpression of the dominant-negative Rho mutant N17Rac1 completely inhibited AngII-induced intracellular oxidation and ANF promoter activity, while N19RhoA partially inhibited it, and N17Cdc42 had no effect. Indeed, Sim inhibited cardiac hypertrophy and decreased myocardial Rac1 activity and O2*- production in rats treated with AngII infusion or subjected to transaortic constriction. These findings suggest that statins prevent the development of cardiac hypertrophy through an antioxidant mechanism involving inhibition of Rac1.

Overexpression of cytochrome P450 CYP2J2 protects against hypoxia-reoxygenation injury in cultured bovine aortic endothelial cells.

CYP2J2 is abundant in human heart and its arachidonic acid metabolites, the epoxyeicosatrienoic acids (EETs), have potent vasodilatory, antiinflammatory and cardioprotective properties. This study was designed to examine the role of CYP2J2 in hypoxia-reoxygenation-induced injury in cultured bovine aortic endothelial cells (BAECs). Early passage BAECs were exposed to 24-h hypoxia followed by 4-h reoxygenation (HR). HR resulted in cell injury, as indicated by significant increases in lactate dehydrogenase (LDH) release and trypan blue stained cells (p < 0.01) and was associated with a decrease in CYP2J2 protein expression. Transfection of BAECs with the CYP2J2 cDNA resulted in increased CYP2J2 expression and arachidonic acid epoxygenase activity, compared with cells transfected with an irrelevant green fluorescent protein (GFP) cDNA. HR induced significant injury in GFP-transfected BAECs, as indicated by increases in LDH release and trypan blue-stained cells (p < 0.01); however, the HR-induced injury was markedly attenuated in CYP2J2-transfected cells (p < 0.01). HR increased cellular 8-iso-prostaglandin F(2alpha) (p < 0.05), and decreased eNOS expression, L-arginine uptake and conversion, and nitrite production (p < 0.01) in GFP-transfected BAECs. CYP2J2 transfection attenuated the HR-induced increase in 8-iso-prostaglandin F(2alpha) (p < 0.05) and decreased the amount of extracellular superoxide detected by cytochrome c reduction under normoxic conditions (p < 0.05) but did not significantly affect HR-induced decreases in eNOS expression, L-arginine uptake and conversion, and nitrite production. Treatment of BAECs with synthetic EETs and/or epoxide hydrolase inhibitors also showed protective effects against HR injury (p < 0.05). These observations suggest: (1) HR results in endothelial injury and decreased CYP2J2 expression; (2) transfection with the CYP2J2 cDNA protects against HR injury; and (3) the cytoprotective effects of CYP2J2 may be mediated, at least in part, by antioxidant effects.

Mevastatin, an HMG-CoA reductase inhibitor, reduces stroke damage and upregulates endothelial nitric oxide synthase in mice.

BACKGROUND AND PURPOSE: The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) lower serum cholesterol and decrease the incidence of stroke and cardiovascular disease. There is growing evidence that statins exert some of their beneficial effects independent of cholesterol lowering. Indeed, we have previously demonstrated that chronic simvastatin administration upregulates endothelial nitric oxide synthase (eNOS), resulting in more functional protein, augmentation of cerebral blood flow, and neuroprotection in a murine model of cerebral ischemia. In this report we examined whether another member of the statin family shared these effects and whether eNOS upregulation is sustained with longer treatment. METHODS: Mevastatin (2 mg/kg or 20 mg/kg per day) was administered to 18- to 22-g male mice for 7, 14, or 28 days before 2-hour middle cerebral artery occlusion with the use of the filament model (n=9 to 12). Neurological deficits and cerebral infarct volumes were assessed at 24 hours. Arterial blood pressure and gases, relative cerebral blood flow, and blood cholesterol levels were monitored in a subset of animals (n=5). Absolute cerebral blood flow was measured by the [(14)C]iodoamphetamine indicator fractionation technique (n=6). eNOS mRNA and protein levels were determined. RESULTS: Mevastatin increased levels of eNOS mRNA and protein, reduced infarct size, and improved neurological deficits in a dose- and time-dependent manner. Greatest protection was seen with 14- and 28-day high-dose treatment (26% and 37% infarct reduction, respectively). Cholesterol levels were reduced only after 28 days of treatment and did not correlate with infarct reduction. Baseline absolute cerebral blood flow was 30% higher after 14-day high-dose treatment. CONCLUSIONS: Chronic prophylactic treatment with mevastatin upregulated eNOS and augmented cerebral blood flow. These changes occurred in the absence of changes in serum cholesterol levels, were sustained for up to 1 month of treatment, and resulted in neuroprotection after middle cerebral artery occlusion.

Activation of Galpha s mediates induction of tissue-type plasminogen activator gene transcription by epoxyeicosatrienoic acids.

The epoxyeicosatrienoic acids (EETs) are products of cytochrome P450 (CYP) epoxygenases that have vasodilatory and anti-inflammatory properties. Here we report that EETs have additional fibrinolytic properties. In vascular endothelial cells, physiological concentrations of EETs, particularly 11,12-EET, or overexpression of the endothelial epoxygenase, CYP2J2, increased tissue plasminogen activator (t-PA) expression by 2.5-fold without affecting plasminogen activator inhibitor-1 expression. This increase in t-PA expression correlated with a 4-fold induction in t-PA gene transcription and a 3-fold increase in t-PA fibrinolytic activity and was blocked by the CYP inhibitor, SKF525A, but not by the calcium-activated potassium channel blocker, charybdotoxin, indicating a mechanism that does not involve endothelial cell hyperpolarization. The t-PA promoter is cAMP-responsive, and induction of t-PA gene transcription by EETs correlated with increases in intracellular cAMP levels and, functionally, with cAMP-driven promoter activity. To determine whether increases in intracellular cAMP levels were due to modulation of guanine nucleotide-binding proteins, we assessed the effects of EETs on Galpha(s) and Galpha(i2). Treatment with EETs increased Galpha(s), but not Galpha(i2), GTP-binding activity by 3.5-fold. These findings indicate that EETs possess fibrinolytic properties through the induction of t-PA and suggest that endothelial CYP2J2 may play an important role in regulating vascular hemostasis.

Regulation of myogenic terminal differentiation by the hairy-related transcription factor CHF2.

We have recently cloned a novel basic helix-loop-helix factor, CHF2, that functions as a transcriptional repressor. To address its role in the regulation of myogenic terminal differentiation, we analyzed its expression pattern during C2C12 mouse myotube formation. In undifferentiated myoblasts, CHF2 is expressed at high levels. After induction of myotube formation in low serum, CHF2 expression is barely detectable at 3 days after induction. Myogenin expression, in contrast, peaks at 3 days. In transiently transfected 10T1/2 embryonic fibroblasts, CHF2 inhibited MyoD-dependent activation of the myogenin promoter in a dose-dependent fashion. Electrophoretic mobility shift analysis indicated that CHF2 inhibits the binding of the MyoD.E47 heterodimer to the E-box binding site. CHF2 also inhibited myogenic conversion of 10T1/2 cells by MyoD, as measured by skeletal myosin heavy chain protein expression. Coimmunoprecipitation analysis indicated that CHF2 forms a protein complex with MyoD. Mutational analysis of CHF2 indicated that the repression activity for both transcription and myogenic conversion mapped to a hydrophobic carboxyl-terminal region and did not require either the basic helix-loop-helix or YRPW motifs. Our data indicate that CHF2 functions as a transcriptional repressor of myogenesis by formation of an inactive heterodimeric complex with MyoD and likely plays an important role in muscle development.

Induction of endothelial-leukocyte interaction by interferon-gamma requires coactivation of nuclear factor-kappaB.

To determine whether nuclear factor (NF)-kappaB is necessary to confer endothelial cell responsiveness to interferon (INF)-gamma in terms of vascular cell adhesion molecule (VCAM)-1 expression and leukocyte adhesion, human endothelial cells were treated with IFN-gamma in the presence of low concentrations (LCs) of interleukin (IL)-1alpha (

Simvastatin upregulates coronary vascular endothelial nitric oxide production in conscious dogs.

Statin drugs can upregulate endothelial nitric oxide (NO) synthase (eNOS) in isolated endothelial cells independent of lipid-lowering effects. We investigated the effect of short-term simvastatin administration on coronary vascular eNOS and NO production in conscious dogs and canine tissues. Mongrel dogs were instrumented under general anesthesia to measure coronary blood flow (CBF). Simvastatin (20 mg. kg(-1). day(-1)) was administered orally for 2 wk; afterward, resting CBF was found to be higher compared with control (P < 0.05) and veratrine- (activator of reflex cholinergic NO-dependent coronary vasodilation) and ACh-mediated coronary vasodilation were enhanced (P < 0.05). Response to endothelium-independent vasodilators, adenosine and nitroglycerin, was not potentiated. After simvastatin administration, plasma nitrate and nitrite (NO(x)) levels increased from 5.22 +/- 1.2 to 7. 79 +/- 1.3 microM (P < 0.05); baseline and agonist-stimulated NO production in isolated coronary microvessels were augmented (P < 0.05); resting in vivo myocardial oxygen consumption (MVO(2)) decreased from 6.8 +/- 0.6 to 5.9 +/- 0.4 ml/min (P < 0.05); NO-dependent regulation of MVO(2) in response to NO agonists was augmented in isolated myocardial segments (P < 0.05); and eNOS protein increased 29% and eNOS mRNA decreased 50% in aortas and coronary vascular endothelium. Short-term administration of simvastatin in dogs increases coronary endothelial NO production to enhance NO-dependent coronary vasodilation and NO-mediated regulation of MVO(2).

Inhibition of vascular smooth muscle cell proliferation by sodium salicylate mediated by upregulation of p21(Waf1) and p27(Kip1).

BACKGROUND: Salicylates may have direct vascular effects by mechanisms that are independent of platelet inhibition. METHODS AND RESULTS: We investigated the effect of salicylates on vascular smooth muscle cell (SMC) proliferation in response to platelet-derived growth factor (PDGF) in vitro. Salicylate concentrations of 5 and 10 mmol/L inhibited serum- or PDGF-induced SMC cell count and [(3)H]thymidine incorporation by 62% and 81%, respectively. There was no evidence of cellular toxicity or apoptosis as determined by trypan blue exclusion and FACS analyses. Because cell cycle progression is regulated by hyperphosphorylation of the retinoblastoma (Rb) protein, we examined the effects of salicylate on Rb hyperphosphorylation. Treatment with salicylate, but not indomethacin, inhibited nuclear factor-kappaB activation and completely abolished Rb hyperphosphorylation in PDGF-treated SMCs. This effect was associated with a decrease in cyclin-dependent kinase (Cdk)-2 and, to a lesser extent, Cdk-6, but not Cdk-4 activity, without changes in Cdk-2, -4, and -6 and cyclin D and E protein levels. Because Cdk-2 activity is regulated by the Cdk inhibitors p21(Waf1) and p27(Kip1), we studied the effects of salicylate on p21(Waf1) and p27(Kip1) expression. Treatment with salicylate prevented PDGF-induced downregulation of p21(Waf1) and p27(Kip1) but not of the Cdk-4/-6 inhibitor p16(Ink4). CONCLUSIONS: These findings indicate that high doses of salicylates inhibit SMC proliferation by cell cycle arrest at the G(1)-S phase and suggest a beneficial role for high-dose salicylates in the treatment of vascular proliferative disorders.

Interaction of oestrogen receptor with the regulatory subunit of phosphatidylinositol-3-OH kinase.

Oestrogen produces diverse biological effects through binding to the oestrogen receptor (ER). The ER is a steroid hormone nuclear receptor, which, when bound to oestrogen, modulates the transcriptional activity of target genes. Controversy exists, however, concerning whether ER has a role outside the nucleus, particularly in mediating the cardiovascular protective effects of oestrogen. Here we show that the ER isoform, ER alpha, binds in a ligand-dependent manner to the p85alpha regulatory subunit of phosphatidylinositol-3-OH kinase (PI(3)K). Stimulation with oestrogen increases ER alpha-associated PI(3)K activity, leading to the activation of protein kinase B/Akt and endothelial nitric oxide synthase (eNOS). Recruitment and activation of PI(3)K by ligand-bound ER alpha are independent of gene transcription, do not involve phosphotyrosine adapter molecules or src-homology domains of p85alpha, and extend to other steroid hormone receptors. Mice treated with oestrogen show increased eNOS activity and decreased vascular leukocyte accumulation after ischaemia and reperfusion injury. This vascular protective effect of oestrogen was abolished in the presence of PI(3)K or eNOS inhibitors. Our findings define a physiologically important non-nuclear oestrogen-signalling pathway involving the direct interaction of ER alpha with PI(3)K.