Discovery of the c-Jun N-Terminal Kinase Inhibitor

As a result of emerging biological data suggesting that within the c-Jun N-terminal kinase (JNK) family, JNK1 and not JNK2 or JNK3 may be primarily responsible for fibrosis pathology, we sought to identify JNK inhibitors with an increased JNK1 bias relative to our previous clinical compound tanzisertib (CC-930). This manuscript reports the synthesis and structure-activity relationship (SAR) studies for a novel series of JNK inhibitors demonstrating an increased JNK1 bias. SAR optimization on a series of 2,4-dialkylamino-pyrimidine-5-carboxamides resulted in the identification of compounds possessing low nanomolar JNK inhibitory potency, overall kinome selectivity, and the ability to inhibit cellular phosphorylation of the direct JNK substrate c-Jun. Optimization of physicochemical properties in this series resulted in compounds that demonstrated excellent systemic exposure following oral dosing, enabling in vivo efficacy studies and the selection of a candidate for clinical development, CC-90001, which is currently in clinical trials (Phase II) in patients with idiopathic pulmonary fibrosis (NCT03142191).

Treating cat allergy with monoclonal IgG antibodies that bind allergen and prevent IgE engagement

Acute allergic symptoms are caused by allergen-induced crosslinking of allergen-specific immunoglobulin E (IgE) bound to Fc-epsilon receptors on effector cells. Desensitization with allergen-specific immunotherapy (SIT) has been used for over a century, but the dominant protective mechanism remains unclear. One consistent observation is increased allergen-specific IgG, thought to competitively block allergen binding to IgE. Here we show that the blocking potency of the IgG response to Cat-SIT is heterogeneous. Next, using two potent, pre-selected allergen-blocking monoclonal IgG antibodies against the immunodominant cat allergen Fel d 1, we demonstrate that increasing the IgG/IgE ratio reduces the allergic response in mice and in cat-allergic patients: a single dose of blocking IgG reduces clinical symptoms in response to nasal provocation (ANCOVA, p = 0.0003), with a magnitude observed at day 8 similar to that reported with years of conventional SIT. This study suggests that simply augmenting the blocking IgG/IgE ratio may reverse allergy.

Jun N-terminal kinase as a potential molecular target for prevention and treatment of dermal fibrosis

OBJECTIVES

The hallmark of systemic sclerosis (SSc) is the accumulation of extracellular matrix proteins by pathologically activated fibroblasts. This study analysed the antifibrotic effects of the selective c-Jun N-terminal kinase (JNK) inhibitor, CC-930, which recently entered first clinical trials as a novel antifibrotic approach.

METHODS

Phosphorylated c-Jun was detected by western blot and immunohistochemistry. The model of bleomycin-induced dermal fibrosis and the tight skin 1 (TSK1) mouse model were used to investigate the effects of CC-930 on the prevention of experimental fibrosis. The potential of CC-930 to induce regression of fibrosis was assessed in a modified model of established fibrosis.

RESULTS

Transforming growth factor beta (TGFβ) and platelet-derived growth factor (PDGF) activate JNK and stimulate the phosphorylation of its downstream target c-Jun. Incubation with CC-930 prevented the phosphorylation of c-Jun and reduced the stimulatory levels of these cytokines on the release of collagen. Inhibition of JNK prevented dermal thickening, myofibroblast differentiation and the accumulation of collagen in a dose-dependent manner in mice challenged with bleomycin and in TSK1 mice. In addition to the prevention of fibrosis, treatment with pharmacologically relevant doses of CC-930 also induced regression of established experimental fibrosis.

CONCLUSIONS

These data identify JNK as a downstream mediator of the pro-fibrotic effects of of TGFβ and PDGF in SSc fibroblasts. Selective inhibition of JNK by CC-930 exerted potent antifibrotic effects in vitro and in different models in vivo. JNK might thus be a novel molecular target for the treatment of fibrosis in SSc.

Evaluation of JNK blockade as an early intervention treatment for type 1 diabetic nephropathy in hypertensive rats

BACKGROUND/AIMS

The c-Jun amino-terminal kinase (JNK) signaling pathway is activated in human kidney diseases and promotes renal injury in experimental glomerulonephritis. In this study, we examined whether JNK signaling plays a role in the development of diabetic nephropathy or in regulating hypertension, which exacerbates diabetic renal injury.

METHODS

Diabetes was induced in spontaneously hypertensive rats (SHR) using streptozotocin. At week 16 of diabetes, rats with equivalent hyperglycemia and albuminuria were randomized into groups which received no treatment, vehicle alone or a selective JNK inhibitor (CC-930, 60 mg/kg/bid) for 10 weeks. These rats were assessed for hypertension and progression of renal damage.

RESULTS

At week 16, diabetic rats showed increased kidney JNK activation compared with nondiabetic controls. Effective JNK inhibition was demonstrated at week 26 by reductions in c-Jun phosphorylation. CC-930 did not affect blood pressure, kidney hypertrophy, glomerular hyperfiltration, podocyte loss, glomerular fibrosis or tubulointerstitial injury in diabetic SHR. However, CC-930 reduced macrophages and ccl2 mRNA levels in diabetic kidneys. In contrast, CC-930 exacerbated albuminuria at week 26, which was associated with reduced glomerular mRNA levels of the podocyte-specific molecules, nephrin and podocin.

CONCLUSION

JNK inhibition does not prevent the progression of early diabetic renal injury in hypertensive rats, which contrasts with the ability of JNK inhibition to suppress albuminuria and injury in experimental glomerulonephritis.

JNK signalling in human and experimental renal ischaemia/reperfusion injury

BACKGROUND

Ischaemia/reperfusion (I/R) is an important factor in delayed graft function in renal transplantation and is a determinant of long-term graft outcome. This study examined the role of c-Jun N-terminal kinase (JNK) signalling in human and experimental renal I/R injury.

METHODS

Biopsies obtained 15-20 min after reperfusion of human renal allografts were examined for JNK signalling by immunostaining for phospho-c-Jun. To examine the pathologic role of JNK signalling, a selective JNK inhibitor (CC-401) was administered to rats before or after the induction of a 30-min period of bilateral renal ischaemia followed by reperfusion. Renal function and tubular damage were analysed.

RESULTS

Substantial JNK activation was evident in tubular epithelial cells in kidneys from deceased donors (n = 30) which was less prominent in kidneys from live donors (n = 7) (44.6 +/- 24.8% vs 29.1 +/- 20% p-c-Jun+, respectively; P < 0.05), whereas biopsies of thin basement membrane disease exhibited little, or no, p-c-Jun staining. The degree of p-c-Jun staining correlated with ischaemic time in deceased donor allografts, but not with graft function. Administration of CC-401 to rats prior to bilateral renal I/R prevented acute renal failure and largely prevented tubular damage, leucocyte infiltration and upregulation of pro-inflammatory molecules. However, delaying CC-401 treatment until 1 h after reperfusion (after the peak of JNK activation) had no protective effect.

CONCLUSIONS

We have identified acute activation of the JNK signalling pathway following I/R in human kidney allografts. Experimental studies indicate that blockade of JNK signalling, commenced prior to this activation, can prevent acute tubular necrosis and renal dysfunction secondary to I/R injury.

CC-4047 promotes Th1 cell differentiation and reprograms polarized human Th2 cells by enhancing transcription factor T-bet

The IMiDs immunomodulatory drugs are an expanding family of compounds under investigation in a broad range of diseases because they exhibit immunomodulatory and anti-tumorigenic properties. Although the molecular targets remain unidentified, the broad activity of select IMiDs immunomodulatory drugs on cell signaling pathways and transcription regulation has been partly described. One characteristic of these compounds is their ability to act as a co-stimulus of TCR ligation leading to increased IL-2, TNF-alpha and IFN-gamma expression indicative of a Th1 phenotype. Because clinical evidence for this response has been observed in thalidomide and lenalidomide treated patients, we investigated the effect of CC-4047 on T cell activation and differentiation at the molecular level. We used primary human CD4(+) T cells as a model and found that CC-4047 enhances the expression of transcription factor T-bet in both naive and pre-polarized Th2 cells. This modulation leads to upregulation of Th1 markers and cytokine production. By increasing the expression of T-bet, CC-4047 promotes the differentiation of naive T-cells to Th1 as well as effectively reverting Th2 cells into Th1-like effector cells in vitro. These findings elucidate a novel mechanism of action of CC-4047 on T cell differentiation, suggesting that certain IMiDs immunomodulatory drugs may have expanded clinical application in treating both allergic diseases and certain T cell lymphomas where a predominant Th2 phenotype is displayed.

A pathogenic role for JNK signaling in experimental anti-GBM glomerulonephritis

Activation of the c-Jun NH2-terminal kinase (JNK) signaling pathway is involved in the immune response; however, little is known of its role in immune-induced renal injury. In this study, we examine JNK signaling in the rat anti-glomerular basement membrane (GBM) disease model using CC-401, a specific JNK inhibitor. Animals were given CC-401, vehicle alone or no treatment starting before anti-GBM serum injection and continued treatment until killing. In acute disease, CC-401 blocked JNK signaling and reduced proteinuria in the first 24 h. The transient neutrophil influx seen at 3 h of disease was not affected, however. Continued CC-401 treatment suppressed glomerular and tubulointerstitial damage usually seen at 14 days. The protective effect may be due to modulation of macrophage activation, as CC-401 had no effect upon glomerular macrophage infiltration at day 14 despite the suppression of glomerular lesions and a marked reduction in renal tumor necrosis factor-alpha and inducible nitric oxide synthase messenger RNA levels. Treatment with CC-401 had no apparent effect on T cell or humoral immune responses. These studies suggest that JNK signaling promotes renal injury in acute and progressive rat anti-GBM disease. JNK inhibitors may be a novel therapeutic approach for the treatment of human glomerulonephritis.

Suppression of alloreactivity and allograft rejection by SP600125, a small molecule inhibitor of c-Jun N-terminal kinase

BACKGROUND

c-Jun N-terminal kinase (JNK) is reported to play crucial roles in T-cell activation and differentiation, and SP600125 is a small molecule that inhibits JNK. The aim of this study was to examine immunosuppressive action of this compound.

METHODS

Rat heterotopic heart transplantation, popliteal lymph node (PLN) hyperplasia bioassay and lymphocyte proliferation assay.

RESULTS

SP600125 treatment reduced histological rejection, and dose-dependently extended median survival time of cardiac allografts from 7 days (vehicle) up to 20 days (40 mg/kg/day). Alloantigen-induced PLN hyperplasia was also inhibited by SP600125 in a similar fashion. SP600125 suppressed mixed lymphocyte reaction and OX52-positive lymphocyte proliferation (IC50: 1.5-5.7 microM). Thus, SP600125 inhibits both T-lymphocyte expansion in vitro and T-cell-mediated alloimmune responses in vivo. In addition, SP600125 interacted with cyclosporine additively to prolong cardiac allograft survival.

CONCLUSION

Our data provide the first evidence indicating the potential for JNK as a therapeutic target to inhibit the alloimmune response.

Attenuation of ozone-induced airway inflammation and hyper-responsiveness by c-Jun NH2 terminal kinase inhibitor SP600125

Ozone has potent oxidizing properties, and exposure to ozone causes airway hyper-responsiveness (AHR) and lung inflammation. We determined the importance of c-Jun NH(2) terminal kinase (JNK), a member of the mitogen-activated protein kinase pathway, in ozone-induced AHR and inflammation. SP600125 [anthra[1,9-cd] pyrazol-6 (2H)-one], a specific JNK inhibitor (30 mg/kg) or vehicle, was administered by intraperitoneal injection before and after ozone exposure (3 ppm for 3 h). SP600125 significantly reduced total cells, and neutrophils in bronchoalveolar fluid recovered at 20 to 24 h after exposure and inhibited ozone-induced AHR. Ozone exposure induced activation of JNK in the lung as measured by the expression of phosphorylated-c-Jun, an effect abolished by SP600125. Gene-microarray analysis revealed that ozone increased the expression of over 400 genes by more than 2-fold, including interleukin-6 (IL-6), CXCL1 (keratinocyte cytokine), and CCL2 (monocyte chemoattractant protein-1). SP600125 modulated the expression of a subset of 29 ozone-induced genes; IL-6 and CCL2 expression were further increased, whereas the expression of metallothionein 1, hemopexin, and mitogen-activated 3 kinase 6 was decreased in SP600125-treated ozone-exposed mice. Changes in mRNA for IL-6, CXCL1, and CCL2 were confirmed by real-time polymerase chain reaction. Ozone also decreased the expression of over 500 genes, with the most potent effect on angiopoietin-1. SP600125 modulated the expression of 15 of these genes, and in particular, SP600125 reversed ozone-induced decrease in expression of the redox-sensitive transcription factor, hypoxia-induced factor-1alpha. This study highlights an important role for JNK in response to oxidative stress through modulation of specific inflammatory and redox mediators. Inhibition of JNK with small molecule kinase inhibitors may be a means of reducing ozone-induced inflammation and AHR.

c-Jun N-terminal kinase-dependent mechanisms in respiratory disease

Respiratory diseases pose a multifaceted dilemma. Although the symptoms and pathology are obvious and provide multiple opportunities for therapeutic investigation, at the same time, the molecular complexities and prioritisation are overwhelming. Even within a disease such as asthma, the number of inducers, cell types, secondary mediators, chemical changes, immune responses and tissue modifications is remarkable. One means of therapeutically targeting this complexity is to identify individual factors responsible for regulating multiple disease processes. The mitogen-activated protein kinase family integrates multiple diverse stimuli, and, in turn, initiates a cell response by phosphorylating and thereby modulating the activity of many target proteins. The c-Jun N-terminal kinase is a critical regulator of pro-inflammatory genes, tissue remodelling and apoptosis, and, therefore, represents an attractive target for novel therapies. Pre-clinical and clinical investigation into the efficacy of c-Jun N-terminal kinase inhibitors has been ongoing since the late 1990s. Over the course of this work, hypotheses have shifted as to the role of c-Jun N-terminal kinase in the many processes that promote allergic, inflammatory, obstructive and fibrotic diseases of the lung. Inhibition of c-Jun N-terminal kinase may indeed provide a means of suppressing more pathological mechanisms in respiratory disease than first suspected.

A Pathogenic Role for c-Jun Amino-Terminal Kinase Signaling in Renal Fibrosis and Tubular Cell Apoptosis

Renal fibrosis and tubular apoptosis are common mechanisms of progressive kidney disease. In vitro studies have implicated the c-Jun amino-terminal kinase (JNK) pathway in these processes. Both of the major JNK isoforms, JNK1 and JNK2, are expressed in the kidney, but their relative contribution to JNK signaling is unknown. This study investigated the role of JNK signaling in renal fibrosis and tubular apoptosis in the unilateral ureteral obstruction model using two different approaches: (1) Mice that were deficient in either JNK1 or JNK2 and (2) a specific inhibitor of all JNK isoforms, CC-401. Western blotting and immunostaining identified a marked increase in JNK signaling in the obstructed kidney, with substantial redundancy between JNK1 and JNK2 isoforms. Administration of CC-401 blocked JNK signaling in the rat obstructed kidney and significantly inhibited renal fibrosis in terms of interstitial myofibroblast accumulation and collagen IV deposition. This effect was attributed to suppression of gene transcription for the profibrotic molecules TGF-beta1 and connective tissue growth factor. CC-401 treatment also significantly reduced tubular apoptosis in the obstructed kidney. Genetic deletion of JNK1 or JNK2 did not protect mice from renal fibrosis in the unilateral ureteral obstruction model, but JNK1 deletion did result in a significant reduction in tubular cell apoptosis. In conclusion, this is the first study to demonstrate that JNK signaling plays a pathogenic role in renal fibrosis and tubular apoptosis. Furthermore, JNK1 plays a nonredundant role in tubular cell apoptosis. These studies identify the JNK pathway as a potential therapeutic target in progressive kidney disease.

Pro-inflammatory signaling by Jun-N-terminal kinase in inflammatory bowel disease

Since Jun-N-terminal kinase participates in intracellular signaling cascades resulting in inflammatory responses, inhibiting this pathway may represent a new treatment for inflammatory bowel disease including ulcerative colitis and Crohn's disease. However, the functional significance of the activation of this kinase in inflammatory bowel disease remains unclear. We investigated whether Jun-N-terminal kinase activation is increased in inflammatory bowel disease and analyzed the effects of SP600125, which decreases inflammatory cytokine synthesis by inhibiting the phosphorylation of this kinase. Phosphorylation of the kinase was examined in affected human colon using an enzyme-linked immunosorbent assay and immunohistochemistry. The effect of SP600125 on cytokine production was examined in cultures of patients' leukocytes and colonic tissue. Finally, rats received injection of SP600125 (30 mg/kg, s.c.) or vehicle twice daily 2 h before the induction of colitis with dextran sulfate sodium. SP600125 effects were determined observationally and histologically. Colonic tissue contained increased phosphorylated kinase in patients with inflammatory bowel disease with expression localized to the nucleus of epithelial and lamina propria mononuclear cells in lesions. Culturing mononuclear cells or colonic tissue with SP600125 down-regulated inflammatory cytokine production. Prophylactic treatment with SP600125 significantly reduced clinical and pathological scores in dextran sulfate sodium-treated rats. This first demonstration of the pathogenetic role of Jun-N-terminal kinase in the development of intestinal inflammation suggests that inhibiting its phosphorylation could benefit patients with inflammatory bowel disease.

Activation of c-Jun N-terminal kinase (JNK) signalling in experimentally induced gastric lesions in rats

The c-Jun N-terminal kinase (JNK) participates in intracellular signalling cascades that mediate inflammatory responses. Therefore, the JNK signalling may be involved in gastric injury and inhibition of this pathway may form the basis of a new strategy for the treatment of gastric injury. The aim of this study was to determine whether JNK participates in the formation of gastric lesions in an experimental model. Acute gastric injury was induced in Sprague-Dawley rats by intragastric administration of 100% ethanol. The amount of phospho-JNK in the rat stomach was determined using immunohistochemistry and Western analysis. Animals received subcutaneous injections of a specific JNK inhibitor SP600125 or vehicle and the extent of mucosal damage in the stomach was determined. Western analysis revealed early phosphorylation of JNK and, to a lesser extent, p38 as well as late phosphorylation of the p42/44 extracellular signal-related kinases during the development of gastric lesions. JNK was phosphorylated in epithelial cells and in occasional mononuclear cells present at lesion sites. These cells were rarely found in samples from control specimens. Treatment with SP600125 significantly reduced the extent of gastric lesions. These findings indicate that experimental gastric injury is associated with activation of the JNK signalling pathway, and also suggest that JNK inhibitors may play a role in the treatment of gastric injury in humans.

Potential role of c-Jun NH2-terminal kinase in allergic airway inflammation and remodelling: effects of SP600125

Asthma is a chronic inflammatory disease of the airways associated with structural changes such as increased airway smooth muscle mass, which may contribute to impairment of lung function. To determine whether c-Jun NH2-terminal kinase (JNK) of the mitogen-activated protein kinase signalling pathway participated in these changes, the effects of an inhibitor, SP600125 (anthra [1, 9-cd] pyrazole-6 (2H)-one), were examined in a murine model of chronic airway inflammation and remodelling. Mice sensitised to ovalbumin were exposed to ovalbumin aerosol and were treated with SP600125 [30 mg kg(-1) intraperitoneal (i.p.)] on days of exposure. SP600125 significantly reduced eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid, suppressed eosinophilic inflammation within the bronchial submucosa, inhibited goblet cell hyperplasia, and increased airway smooth muscle cell number in allergen-exposed mice. SP600125 also inhibited allergen-induced increase in bronchial responsiveness. SP600125 inhibited JNK activity in the challenged lungs. Although SP 600125 may also have other effects, we conclude that c-Jun NH2-terminal kinase may play a role in allergen-induced inflammation and remodelling associated with bronchial hyperresponsiveness.

Effect of an inhibitor of Jun N-terminal protein kinase, SP600125, in single allergen challenge in sensitized rats

Jun N-terminal kinase (JNK) has been implicated in the pathogenesis of inflammatory diseases including asthma. We examined the effect of SP600125 (anthra [1,9-cd] pyrazol-6 (2H)-one), a novel inhibitor of JNK in a model of asthma. Brown-Norway rats were sensitized to ovalbumin and treated with SP600125 intraperitoneally (90 mg/kg in total). SP600125 inhibited allergen-induced, increased activity of phosphorylated c-jun but not of phosphorylated-MAPKAPK2, indicative of activation of p38 MAPK, in the lung. SP600125 inhibited macrophage (P < 0.04), lymphocyte (P < 0.05), eosinophil (P < 0.04) and neutrophil (P < 0.005) numbers in bronchoalveolar lavage. Eosinophil and T-cell accumulation in the airways, mRNA expression for interleukin-1beta, tumour necrosis factor-beta, interleukin-3, interleukin-4 and interleukin-5, serum levels of allergen-specific immunoglobulin E and bronchial hyperresponsiveness were not affected by SP600125. Selective inhibition of JNK reduced inflammatory cell egress into the airway lumen after single allergen exposure. The role of JNK mitogen-activated protein kinase activation may be limited in the pathogenesis of bronchial hyperresponsiveness after single allergen exposure.

Differential requirement for c-Jun NH2-terminal kinase in TNFalpha- and Fas-mediated apoptosis in hepatocytes

The c-Jun NH2-terminal kinase (JNK) is involved in the regulation of cell death, but its role in tumor necrosis factor (TNF)-alpha- and Fas-mediated apoptosis in primary cells is not well defined. In primary rat hepatocytes expressing an IkappaB superrepressor, the JNK inhibitor SP600125 strongly decreased TNF-alpha-induced cell death, caspase 3 activation, and DNA laddering. In contrast, SP600125 did not rescue mouse hepatocytes from Fas-induced apoptosis. Apoptosis in mouse hepatocytes, induced by human TNF-alpha, was blocked by SP600125, indicating that TNF-receptor (TNF-R) 1-mediated JNK activation is important for TNF-alpha-induced death. However, mouse TNF-alpha was more efficient than human TNF-alpha in activating JNK and killing mouse hepatocytes, suggesting that TNF-R1 and TNF-R2 cooperate in JNK activation and apoptosis. SP600125 rescued actinomycin D-pretreated hepatocytes and hepatocytes expressing a dominant negative c-Jun from TNF-alpha, indicating that JNK exerts its proapoptotic effect independently of transcription and c-Jun. SP600125 delayed the mitochondrial permeability transition, inhibited cytochrome c release and prevented bid degradation after TNF-alpha, suggesting that JNK-regulated proapoptotic factors act upstream of the mitochondria. Moreover, overexpression of JNK1 activated a mitochondrial death pathway in hepatocytes, albeit less efficiently than TNF-alpha. This study demonstrates that JNK augments TNF-alpha-induced apoptosis in hepatocytes through a signaling pathway that is distinct from the pathway by which it regulates proliferation.

Inhibition of cell proliferation and cell cycle progression by specific inhibition of basal JNK activity: evidence that mitotic Bcl-2 phosphorylation is JNK-independent

The c-Jun NH(2)-terminal kinase (JNK) subgroup of mitogen-activated protein kinases has been implicated largely in stress responses, but an increasing body of evidence has suggested that JNK also plays a role in cell proliferation and survival. We examined the effect of JNK inhibition, using either SP600125 or specific antisense oligonucleotides, on cell proliferation and cell cycle progression. SP600125 was selective for JNK in vitro and in vivo versus other kinases tested including ERK, p38, cyclin-dependent protein kinase 1 (CDK1), and CDK2. SP600125 inhibited JNK activity and KB-3 cell proliferation with the same dose dependence, suggesting that inhibition of proliferation was a direct consequence of JNK inhibition. Inhibition of proliferation by SP600125 was associated with an increase in the G(2)-M and apoptotic fractions of cells but was not associated with p53 or p21 induction. Antisense oligonucleotides to JNK2 but not JNK1 caused highly significant inhibition of cell proliferation. Wild-type mouse fibroblasts responded similarly with proliferation inhibition and apoptosis induction, whereas c-jun(-/-) fibroblasts were refractory to the effects of SP600125, suggesting that JNK signaling to c-Jun is required for cell proliferation. Studies in synchronized KB-3 cells indicated that SP600125 delayed transit time through S and G(2)-M phases. Correspondingly, JNK activity increased in late S phase and peaked in late G(2) phase. During synchronous mitotic progression, cyclin B levels increased concomitant with phosphorylation of c-Jun, H1 histone, and Bcl-2. In the presence of SP600125, mitotic progression was prolonged, and c-Jun phosphorylation was inhibited, but neither H1 nor Bcl-2 phosphorylation was inhibited. However, the CDK inhibitor roscovitine inhibited mitotic Bcl-2 phosphorylation. These results indicate that JNK, and more specifically the JNK2 isoform, plays a key role in cell proliferation and cell cycle progression. In addition, conclusive evidence is presented that a kinase other than JNK, most likely CDK1 or a CDK1-regulated kinase, is responsible for mitotic Bcl-2 phosphorylation.

Allergen-induced inflammation and airway epithelial and smooth muscle cell proliferation: role of Jun N-terminal kinase

Chronic cellular inflammation and airway wall remodelling with subepithelial fibrosis and airway smooth muscle (ASM) cell hyperplasia are features of chronic asthma. Jun N-terminal kinase (JNK) may be implicated in these processes by regulating the transcriptional activity of activator protein (AP)-1. We examined the effects of an inhibitor of JNK, SP600125 (anthra [1,9-cd] pyrazole-6 (2 H)-one), in a model of chronic allergic inflammation in the rat. Rats sensitised to ovalbumin (OA) were exposed to OA-aerosol every third day on six occasions and were treated with SP600125 (30 mg kg-1 b.i.d; 360 mg in total) for 12 days, starting after the second through to the sixth OA exposure. We measured eosinophilic and T-cell inflammation in the airways, proliferation of ASM cells and epithelial cells by incorporation of bromodeoxyuridine (BrdU), and bronchial responsiveness to acetylcholine. SP600125 significantly reduced the number of eosinophils (P<0.05) and lymphocytes (P<0.05) in bronchoalveolar lavage fluid, suppressed eosinophilic (P<0.05) and CD2+ T-cell (P<0.05) infiltration within the bronchial submucosa, and the increased DNA incorporation in ASM (P<0.05) and epithelial cell incorporation (P<0.05). SP600125 did not alter bronchial hyper-responsiveness observed after chronic allergen exposure. Pathways regulated by JNK positively regulate ASM cell proliferation and allergic cellular inflammation following chronic allergen exposure.

The design and synthesis of novel orally active inhibitors of AP-1 and NF-κB mediated transcriptional activation. SAR of In vitro and In vivo studies

We have developed novel orally active quinazoline analogues as inhibitors of AP-1 and NF-kappaB mediated transcriptional activation. Among the derivatives prepared, 1-[2-(2-thienyl)quinazolin-4-ylamino]-3-methyl-3-pyrroline-2,5-dione (10) showed significant activity in an adjuvant-induced arthritis rat model by reducing the swelling by 65% in the non-injected foot. The synthesis, structure-activity relationship, and in vivo activity are described.

JNK: a new therapeutic target for diabetes

Jun N-terminal kinase (JNK) regulates the transcription factor AP-1, which is implicated in the controlled expression of many genes involved in the immune response. For this reason, drug discovery efforts have focused on the development of JNK inhibitors for chronic inflammatory diseases. However, recent genetic evidence and emerging pharmacological data indicate that activated JNK could be critical in causing diabetes, insulin resistance and obesity. Indeed, if JNK is considered as a stress-activated protein kinase, there appear to be multiple mechanisms through which it might promote diabetes.

c-Jun-N-terminal kinase drives cyclin D1 expression and proliferation during liver regeneration

The c-Jun-N-terminal kinase (JNK) pathway is strongly activated after partial hepatectomy (PH), but its role in hepatocyte proliferation is not known. In this study, JNK activity was blocked with the small molecule inhibitor JNK SP600125 in vivo and in vitro as shown by a reduction of c-Jun phosphorylation, AP-1 DNA binding activity, and c-jun messenger RNA (mRNA) expression. SP600125 inhibited proliferating cell nuclear antigen (PCNA) expression, cyclin D1 mRNA and protein expression and reduced mitotic figures after PH. Survival was reduced significantly 3 days after PH in SP600125-treated versus vehicle-treated rats (3 of 11 vs. 8 of 9, P <.01). In epidermal growth factor (EGF)-treated primary cultures of rat hepatocytes, SP600125 decreased (3)H-thymidine uptake, cyclin D1 mRNA and protein expression, and inhibited the EGF-induced transcription of a cyclin D1 promoter-driven reporter gene. The defective regeneration and the decreased survival in SP600125-treated rats did not result from a major increase in apoptosis as shown by normal levels of caspase 3 activity and only slight increases in apoptotic figures. In conclusion, our data show that JNK drives G0 to G1 transition in hepatocytes and that cyclin D1 is a downstream target of the JNK pathway during liver regeneration.

Potential new therapeutics for Waldenstrom's macroglobulinemia

Thalidomide the first commercially available immune modulatory drug (IMiD), has activity in the treatment of Waldenstrom's macroglobulinemia (WM), as well as multiple myeloma, myelodysplastic syndrome, myelofibrosis with myeloid metaplasia, chronic lymphocytic leukemia (CLL), and B-cell lymphomas. Although its molecular mechanisms of action have not yet been elucidated, thalidomide and the IMiDs affect a variety of cytokines and inflammatory mediators including tumor necrosis factor-alpha (TNFalpha), interleukin (IL)-1beta, interferon gamma (IFNgamma), IL-6, IL-10, IL-12, and COX-2 and angiogenesis factors such as vascular endothelial growth factor (VEGF) and its receptor. The IMiDs also affect adhesion molecules such as ICAM-1, ICAM-2, and L-CAM, in addition to preferentially stimulating CD8 cells and expanding natural killer (NK) cell populations. Since most IMiDs share these properties, it would be expected that the second-generation IMiDs (REVIMID, ACTIMID) would have activity similar to thalidomide in WM with an improved safety profile. TNFalpha and angiogenesis most likely play a role in promoting the growth and development of WM. The selective cytokine inhibitory drugs (SelCIDs) are potent phosphodiesterase 4 (PDE-4) inhibitors that inhibit TNFalpha production and are highly antiangiogenic. In addition, inhibition of PDE-4 induces apoptosis in human CLL lymphocytes. It is therefore expected that the SelCIDs might have activity in Waldenstrom's tumors. Jun N-terminal kinase (JNK) is a component of signaling cascades that modulate apoptosis, the induction of an inflammatory response via the AP-1 pathway, and modulation of cellular proliferation. In a variety of tumors, including multiple myeloma, JNK is induced as part of a protective mechanism. It is hypothesized that inhibition of JNK activity might allow other chemotherapeutic agents to be more effective in a similar manner to corticosteroids. Work is in progress to evaluate this. Inhibitors of the E3 subunit of ubiquitin ligase may also selectively modulate the expression of receptors, growth factors, and transcription factors essential to the growth, survival, and spread of tumors. We hypothesize that the IMiDs, SelCIDs, JNK inhibitors, and ligase inhibitors will be the basis for a new nonchemotherapeutic approach to the treatment of WM and other related diseases.

Differential requirement for NF-kappaB-inducing kinase in the induction of NF-kappaB by IL-1beta, TNF-alpha, and Fas

In this study, we examined the role of the nuclear factor-kappaB (NF-kappaB)-inducing kinase (NIK) in distinct signaling pathways leading to NF-kappaB activation. We show that a dominant-negative form of NIK (dnNIK) delivered by adenoviral (Ad5dnNIK) vector inhibits Fas-induced IkappaBalpha phosphorylation and NF-kappaB-dependent gene expression in HT-29 and HeLa cells. Interleukin (IL)-1beta- and tumor necrosis factor-alpha (TNF-alpha)-induced NF-kappaB activation and kappaB-dependent gene expression are inhibited in HeLa cells but not in Ad5dnNIK-infected HT-29 cells. Moreover, Ad5dnNIK failed to sensitize HT-29 cells to TNF-alpha-induced apoptosis at an early time point. However, cytokine- and Fas-induced signals to NF-kappaB are finally integrated by the IkappaB kinase (IKK) complex, since IkappaBalpha phosphorylation, NF-kappaB DNA binding activity, and IL-8 gene expression were strongly inhibited in HT-29 and HeLa cells overexpressing dominant-negative IKKbeta (Ad5dnIKKbeta). Our findings support the concept that cytokine signaling to NF-kappaB is redundant at the level of NIK. In addition, this study demonstrates for the first time the critical role of NIK and IKKbeta in Fas-induced NF-kappaB signaling cascade.

Expression and regulation of inducible IkappaB kinase (IKK-i) in human fibroblast-like synoviocytes

IkappaB kinase (IKK) plays a key role in the regulation of nuclear factor kappaB (NF-kappaB). We previously demonstrated the expression of two kinases, IKK1 and IKK2, in fibroblast-like synoviocytes (FLS) and determined their functional consequences for inflammatory gene expression in vitro and in vivo. Recently, a novel inducible IkappaB kinase has been described, namely, IKK-i or IKK-epsilon, which is functionally and structurally distinct from constitutively expressed IKK1 and IKK2. Therefore, we investigated the expression and regulation of this novel kinase in FLS from patients with rheumatoid arthritis and osteoarthritis. Interestingly, constitutive gene expression and protein expression were observed in all cell lines examined. TNFalpha stimulation for 24 h increased IKK-i expression 7.2 +/- 1.8-fold in FLS (P < 0.02). IL-1 also significantly increased IKK-i gene expression. Time course experiments demonstrated that IKK-i gene expression increased within 3 h of TNFalpha stimulation and persisted for at least 24 h. Dose-response studies showed that as little as 1 ng/ml of TNFalpha increased IKK-i gene expression. Constitutive IKK-1 gene expression was also noted in rheumatoid arthritis, osteoarthritis, and normal synovium. This is the first report demonstrating constitutive expression and cytokine regulation of this novel kinase in primary human synovial cells.

SP600125, an anthrapyrazolone inhibitor of Jun N-terminal kinase

Jun N-terminal kinase (JNK) is a stress-activated protein kinase that can be induced by inflammatory cytokines, bacterial endotoxin, osmotic shock, UV radiation, and hypoxia. We report the identification of an anthrapyrazolone series with significant inhibition of JNK1, -2, and -3 (K(i) = 0.19 microM). SP600125 is a reversible ATP-competitive inhibitor with >20-fold selectivity vs. a range of kinases and enzymes tested. In cells, SP600125 dose dependently inhibited the phosphorylation of c-Jun, the expression of inflammatory genes COX-2, IL-2, IFN-gamma, TNF-alpha, and prevented the activation and differentiation of primary human CD4 cell cultures. In animal studies, SP600125 blocked (bacterial) lipopolysaccharide-induced expression of tumor necrosis factor-alpha and inhibited anti-CD3-induced apoptosis of CD4(+) CD8(+) thymocytes. Our study supports targeting JNK as an important strategy in inflammatory disease, apoptotic cell death, and cancer.

TAK1/JNK and p38 have opposite effects on rat hepatic stellate cells

After liver injury, hepatic stellate cells (HSCs) undergo a process of activation with expression of smooth muscle alpha-actin (alpha-SMA), an increased proliferation rate, and a dramatic increase in synthesis of type I collagen. The intracellular signaling mechanisms of activation and perpetuation of the activated phenotype in HSCs are largely unknown. In this study the role of the stress-activated protein kinases, c-Jun N-terminal kinase (JNK) and p38, were evaluated in primary cultures of rat HSCs. The effect of JNK was assessed by using an adenovirus expressing a dominant negative form of transforming growth factor beta (TGF-beta)-activated kinase 1 (TAK1) (Ad5dnTAK1) and a new selective pharmacologic inhibitor SP600125. The effect of p38 was assessed with the selective pharmacologic inhibitor SB203580. These kinases were inhibited starting either in quiescent HSCs (culture day 1) or in activated HSCs (culture day 5). Although blocking TAK1/JNK and p38 decreased the expression of alpha-SMA protein in early stages of HSC activation, no effect was observed when TAK1/JNK or p38 were inhibited in activated HSCs. JNK inhibition increased and p38 inhibition decreased collagen alpha1(I) mRNA level as measured by RNase protection assays, with maximal effects observed in early stages of HSC activation. Furthermore, TAK1/JNK inhibition decreased HSC proliferation, whereas p38 inhibition led to an increased proliferation rate of HSCs, independently of its activation status. These results show novel roles for the TAK1/JNK pathway and p38 during HSC activation in culture. Despite similar activators of TAK1/JNK and p38, their functions in HSCs are distinct and opposed.

Inhibitor of nuclear factor kappaB kinase beta is a key regulator of synovial inflammation

OBJECTIVE

Inhibitor of nuclear factor kappaB kinase beta (IkappaB kinase beta, or IKKbeta) has emerged as a key regulator of the transcription factor nuclear factor kappaB (NF-kappaB). Since IKKbeta could have both pro- and antiinflammatory activity, we examined whether its constitutive activation was sufficient to cause a chronic inflammatory disease such as rheumatoid arthritis.

METHODS

Normal Lewis rats were evaluated for paw swelling by plethysmometry and histologic assessment after intraarticular injection of an adenoviral construct encoding the IKKbeta wild-type gene (Ad.IKKbeta-wt); controls received an adenoviral construct encoding green fluorescent protein (Ad.GFP). The rats were killed after 7 days. Additionally, rats were killed 48 hours after intraarticular injection of Ad.IKKbeta-wt or Ad.GFP for studies of IKK activity and NF-kappaB binding. For studies of the effects of inhibition of IKKbeta activity, Lewis rats were immunized with Mycobacterium tuberculosis in mineral oil. The ankle joints were injected on day 12 with an adenoviral construct encoding IKKbeta K-->M (dominant negative, IKKbeta-dn) or Ad.GFP. We evaluated paw swelling and NF-kappaB expression on day 25.

RESULTS

Intraarticular gene transfer of IKKbeta-wt into the joints of normal rats resulted in significant paw swelling and histologic evidence of synovial inflammation. Increased IKK activity was detectable in the IKKbeta-wt-injected ankle joints, coincident with enhanced NF-kappaB DNA binding activity. Intraarticular gene transfer of IKKbeta-dn significantly ameliorated the severity of adjuvant arthritis, accompanied by a significant decrease in NF-kappaB DNA expression in the joints of Ad.IKKbeta-dn-treated animals.

CONCLUSION

IKKbeta plays a key role in rodent synovial inflammation. Intraarticular gene therapy to inhibit IKKbeta activity represents an attractive strategy for the treatment of chronic arthritis.

NF-kappaB stimulates inducible nitric oxide synthase to protect mouse hepatocytes from TNF-alpha- and Fas-mediated apoptosis

BACKGROUND AND AIMS

Hepatocyte apoptosis is induced by tumor necrosis factor alpha (TNF-alpha) and Fas ligand. Although nuclear factor-kappaB (NF-kappaB) activation protects hepatocytes from TNF-alpha-mediated apoptosis, the NF-kappaB responsive genes that protect hepatocytes are unknown. Our aim was to study the role of NF-kappaB activation and inducible nitric oxide synthases (iNOSs) in TNF-alpha- and Fas-mediated apoptosis in hepatocytes.

METHODS

Primary cultures of hepatocytes from wild-type and iNOS knockout mice were treated with TNF-alpha, the Fas agonistic antibody Jo2, a nitric oxide (NO) donor (S-nitroso-N-acetylpenicillamine), an NO inhibitor (N(G)-methyl-L-arginine acetate), and/or adenovirus-expressing NF-kappaB inhibitors.

RESULTS

The IkappaB superrepressor and a dominant-negative form of IkappaB kinase beta (IKKbeta) inhibited NF-kappaB binding activity by TNF-alpha or Jo2 and sensitized hepatocytes to TNF-alpha- and Jo2-mediated apoptosis. TNF-alpha and Jo2 induced iNOS messenger RNA and protein levels through the induction of NF-kappaB. S-nitroso-N-acetylpenicillamine inhibited Bid cleavage, the mitochondrial permeability transition, cytochrome c release, and caspase-8 and -3 activity, and reduced TNF-alpha- and Fas-mediated death in hepatocytes expressing IkappaB superrepressor. N(G)-methyl-L-arginine acetate partially sensitized hepatocytes to TNF-alpha- and Fas-mediated cell killing. TNF-alpha alone or Jo2 alone induced moderate cell death in hepatocytes from iNOS(-)/(-) mice.

CONCLUSIONS

NO protects hepatocytes from TNF-alpha- and Fas-mediated apoptosis. Endogenous iNOS, which is activated by NF-kappaB via IKKbeta, provides partial protection from apoptosis.

Differential role of I kappa B kinase 1 and 2 in primary rat hepatocytes

Nuclear factor-kappa B (NF-kappa B) protects hepatocytes from undergoing apoptosis during embryonic development and during liver regeneration. Activation of NF-kappa B is mediated through phosphorylation of its inhibitor, I kappa B, by a kinase complex that contains 2 I kappa B kinases. We analyzed the differential role of I kappa B kinase 1 (IKK1) and I kappa B kinase 2 (IKK2) in tumor necrosis factor alpha (TNF-alpha)- and interleukin-1 beta (IL-1 beta)-mediated NF-kappa B activation in primary rat hepatocytes. Maximal induction of IKK activity was observed 5 minutes after TNF-alpha and 15 minutes after IL-1 beta treatment, and activated IKK was able to phosphorylate GST-I kappa B (1-54) and GST-p65 (354-551), but not a GST-p65 (354-551) substrate with a serine-to-alanine substitution at position 536. Infection with an adenovirus containing catalytically inactive IKK2K44M (Ad5IKK2dn) completely blocked both TNF-alpha- and IL-1 beta-induced GST-I kappa B and GST-p65 phosphorylation, I kappa B degradation, and NF-kappa B DNA binding. Adenovirally transduced, catalytically inactive IKK1K44M (Ad5IKK1dn) reduced IKK activity and NF-kappa B DNA binding only slightly. Accordingly, Ad5IKK2dn induced apoptosis in 75% (+/-6%) of hepatocytes after 12 hours of TNF-alpha, which was accompanied by activation of caspases 3 and 8, nuclear fragmentation, and DNA laddering. In contrast, Ad5IKK1dn led to 21% (+/-2%) apoptosis in TNF-alpha-treated hepatocytes after 12 hours and comparatively low activity of caspases 3 and 8. Furthermore, Ad5IKK2dn completely blocked the induction of inducible nitric oxide synthase (iNOS), whereas Ad5IKK1dn had no influence on the expression of iNOS. Thus, IKK2 is the main mediator for cytokine-induced NF-kappa B activation in primary hepatocytes and protects against TNF-alpha-induced apoptosis, whereas IKK1 kinase activity is not required for NF-kappa B activation.

Inhibitors of NF-kappaB and AP-1 gene expression: SAR studies on the pyrimidine portion of 2-chloro-4-trifluoromethylpyrimidine-5-[N-(3', 5'-bis(trifluoromethyl)phenyl)carboxamide]

We investigated the structure-activity relationship studies of N-[3, 5-bis(trifluoromethyl)phenyl][2-chloro-4-(trifluoromethyl)pyrimidin-5 -yl]carboxamide (1), an inhibitor of transcription mediated by both NF-kappaB and AP-1 transcription factors, with the goal of improving its potential oral bioavailability. Compounds were examined for cell-based activity, were fit to Lipinski's rule of 5, and were examined for potential gastrointestinal permeability using the intestinal epithelial cell line, Caco-2. Selected groups were substituted at the 2-, 4-, and 5-positions of the pyrimidine ring using solution-phase combinatorial methodology. The introduction of a fluorine in the place of 2-chlorine of 1 resulted in a compound with comparable activity. However, other substitutions at the 2-position resulted in a loss of activity. The trifluoromethyl group at the 4-position could be replaced with a methyl, ethyl, chlorine, or phenyl without a substantial loss of activity. The carboxamide group at the 5-position is critical for activity. If it was moved to the 6-position, the activity was lost. The 2-methyl analogue of 1 (81) showed comparable in vitro activity and improved Caco-2 permeability compared to 1.

Gold(I) and silver(I) metallocryptates based on 2,9-bis(diphenylphosphino)-1,8-naphthyridine

In acetonitrile the rigid diphosphine ligand 2,9-bis(diphenylphosphino)-1,8-naphthyridine (dppn) reacts with (SMe2)AuCl in the presence of NaPF6 to produce a pale-yellow material identified as [Au2Na(mu-dppn)3](PF6)3 (1). In acetonitrile dppn reacts with 2 equiv of (SMe2)AuCl to form the simple Au-Cl adduct of the ligand, Au2Cl2dppn (2). In a fashion analogous to that of the synthesis of 1, the reaction of equimolar AgNO3 with dppn produces the trimetallic species [Ag2(mu-dppn)3Ag](PF6)3 (3) as a bright-yellow material. 1, 2, and 3 were characterized by 31P(1H) NMR spectroscopy, electronic absorption spectroscopy, X-ray crystallography, emission spectroscopy, and elemental analysis. Additionally 1 was further characterized by cyclic voltammetry and mass spectrometry. 1.4.5CH3CN.0.5(C2H5)2O (C107H72Au2F18N10.5NaO) crystallizes in the triclinic space group P1 with a = 15.408(3) A, b = 17.295(3) A, c = 22.425(5) A, alpha = 73.68(1) degrees, beta = 77.32(1) degrees, gamma = 74.18(1) degrees, V = 5451.4(19) A3, and Z = 2. C32H24Au2Cl2N2P2 (2) crystallizes in the monoclinic space group Cc with a = 10.936(2) A, b = 19.860(5) A, c = 20.864(2) A, beta = 118.182(1) degrees, V = 3127.3(8) A3, and Z = 4. Compound 3 crystallizes as the bis-DMSO adduct (C101H84Cl2F18N6O2P9S2) in the monoclinic space group C2/c with a = 28.825(7) A, b = 17.013(3) A, c = 23.916(7) A, beta = 115.23(1) degrees, V = 10609.6(44) A3, and Z = 4. The structures of 1 and 3 contain a three-coordinate metal capping the metallocryptate with an encapsulated ion. The central Ag(I) ion in 3 is positioned off-center to form a short Ag...Ag interaction of 3.145(2) A, while the central Na+ ion of 1 is centrally positioned with long Au...Na interactions of approximately 3.5 A. The solution-state properties of 1 were probed. 1 is emissive, as are the Li, K, and Cs analogues.

Primary human CD4+ T cells contain heterogeneous I kappa B kinase complexes: role in activation of the IL-2 promoter

NF-kappa B transcription factors play an important role in the activation of the IL-2 gene in response to TCR ligation. The release of NF-kappa B factors to the nucleus requires phosphorylation and degradation of the inhibitory kappa-B proteins (I kappa Bs). I kappa B alpha and I kappa B beta phosphorylation is dependent on dual signaling by the TCR and the CD28 accessory receptor. This pathway involves a multisubunit I kappa B kinase (IKK) complex, which includes the IKK alpha (IKK-1) and IKK beta (IKK-2) kinases. We demonstrate that stimulation of primary human CD4+ T cells by CD3/CD28 activates two distinct endogenous IKK complexes, a heterodimeric IKK alpha/beta and a homodimeric IKK beta complex. IKK beta overexpression in a Jurkat cell line resulted in the formation of a constitutively active IKK complex, which was CD3/CD28 inducible. In contrast, ectopic expression of IKK alpha assembled into a complex with negligible I kappa B kinase activity. Moreover, IKK beta, but not IKK alpha, overexpression enhanced transcriptional activation of the CD28 response element in the IL-2 promoter. Conversely, only kinase-inactive IKK beta interfered in the activation of the IL-2 promoter. Sodium salicylate, an inhibitor of IKK beta, but not IKK alpha, activity, inhibited IL-2 promoter activation as well as IL-2 secretion and interfered in activation of both the heterodimeric as well as the homodimeric IKK complexes in primary CD4+ T cells. Taken together, these data demonstrate the presence of an IKK beta-mediated signaling pathway that is activated by TCR and CD28 coligation and regulates IL-2 promoter activity.

Primary Human CD4+ T Cells Contain Heterogeneous IκB Kinase Complexes: Role in Activation of the IL-2 Promoter

NF-κB transcription factors play an important role in the activation of the IL-2 gene in response to TCR ligation. The release of NF-κB factors to the nucleus requires phosphorylation and degradation of the inhibitory κ-B proteins (IκBs). IκBα and IκBβ phosphorylation is dependent on dual signaling by the TCR and the CD28 accessory receptor. This pathway involves a multisubunit IκB kinase (IKK) complex, which includes the IKKα (IKK-1) and IKKβ (IKK-2) kinases. We demonstrate that stimulation of primary human CD4+ T cells by CD3/CD28 activates two distinct endogenous IKK complexes, a heterodimeric IKKα/β and a homodimeric IKKβ complex. IKKβ overexpression in a Jurkat cell line resulted in the formation of a constitutively active IKK complex, which was CD3/CD28 inducible. In contrast, ectopic expression of IKKα assembled into a complex with negligible IκB kinase activity. Moreover, IKKβ, but not IKKα, overexpression enhanced transcriptional activation of the CD28 response element in the IL-2 promoter. Conversely, only kinase-inactive IKKβ interfered in the activation of the IL-2 promoter. Sodium salicylate, an inhibitor of IKKβ, but not IKKα, activity, inhibited IL-2 promoter activation as well as IL-2 secretion and interfered in activation of both the heterodimeric as well as the homodimeric IKK complexes in primary CD4+ T cells. Taken together, these data demonstrate the presence of an IKKβ-mediated signaling pathway that is activated by TCR and CD28 coligation and regulates IL-2 promoter activity.

NF-κB Regulation by IκB Kinase in Primary Fibroblast-Like Synoviocytes

NF-κB is a key regulator of inflammatory gene transcription and is activated in the rheumatoid arthritis (RA) synovium. In resting cells, NF-κB is retained as an inactive cytoplasmic complex by its inhibitor, IκB. Phosphorylation of IκB targets it for proteolytic degradation, thereby releasing NF-κB for nuclear translocation. Recently, two related IκB kinases (IKK-1 and IKK-2) were identified in immortalized cell lines that regulate NF-κB activation by initiating IκB degradation. To determine whether IKK regulates NF-κB in primary cells isolated from a site of human disease, we characterized IKK in cultured fibroblast-like synoviocytes (FLS) isolated from synovium of patients with RA or osteoarthritis. Immunoreactive IKK protein was found to be abundant in both RA and osteoarthritis FLS by Western blot analysis. Northern blot analysis showed that IKK-1 and IKK-2 genes were constitutively expressed in all FLS lines. IKK function in FLS extracts was determined by measuring phosphorylation of recombinant IκB in vitro. IKK activity in both RA and osteoarthritis FLS was strongly induced by TNF-α and IL-1 in a concentration-dependent manner. Activity was significantly increased within 10 min of stimulation and declined to near basal levels within 80 min. Activation of IKK in FLS was accompanied by phosphorylation and degradation of endogenous IκBα as determined by Western blot analysis. Concomitant activation and nuclear translocation of NF-κB was documented by EMSA and immunohistochemistry. Transfection with a dominant negative IKK-2 mutant prevented TNF-α-mediated NF-κB nuclear translocation, whereas a dominant negative IKK-1 mutant had no effect. This is the first demonstration that IKK-2 is a pivotal regulator of NF-κB in primary human cells.

NF-kappa B regulation by I kappa B kinase in primary fibroblast-like synoviocytes

NF-kappa B is a key regulator of inflammatory gene transcription and is activated in the rheumatoid arthritis (RA) synovium. In resting cells, NF-kappa B is retained as an inactive cytoplasmic complex by its inhibitor, I kappa B. Phosphorylation of I kappa B targets it for proteolytic degradation, thereby releasing NF-kappa B for nuclear translocation. Recently, two related I kappa B kinases (IKK-1 and IKK-2) were identified in immortalized cell lines that regulate NF-kappa B activation by initiating I kappa B degradation. To determine whether IKK regulates NF-kappa B in primary cells isolated from a site of human disease, we characterized IKK in cultured fibroblast-like synoviocytes (FLS) isolated from synovium of patients with RA or osteoarthritis. Immunoreactive IKK protein was found to be abundant in both RA and osteoarthritis FLS by Western blot analysis. Northern blot analysis showed that IKK-1 and IKK-2 genes were constitutively expressed in all FLS lines. IKK function in FLS extracts was determined by measuring phosphorylation of recombinant I kappa B in vitro. IKK activity in both RA and osteoarthritis FLS was strongly induced by TNF-alpha and IL-1 in a concentration-dependent manner. Activity was significantly increased within 10 min of stimulation and declined to near basal levels within 80 min. Activation of IKK in FLS was accompanied by phosphorylation and degradation of endogenous I kappa B alpha as determined by Western blot analysis. Concomitant activation and nuclear translocation of NF-kappa B was documented by EMSA and immunohistochemistry. Transfection with a dominant negative IKK-2 mutant prevented TNF-alpha-mediated NF-kappa B nuclear translocation, whereas a dominant negative IKK-1 mutant had no effect. This is the first demonstration that IKK-2 is a pivotal regulator of NF-kappa B in primary human cells.

IkappaB kinase (IKK)-associated protein 1, a common component of the heterogeneous IKK complex

Activation of the transcription factor NF-kappaB is controlled by the sequential phosphorylation, ubiquitination, and degradation of its inhibitory subunit, IkappaB. We recently purified a large multiprotein complex, the IkappaB kinase (IKK) signalsome, which contains two regulated IkappaB kinases, IKK1 and IKK2, that can each phosphorylate IkappaBalpha and IkappaBbeta. The IKK signalsome contains several additional proteins presumably required for the regulation of the NFkappaB signal transduction cascade in vivo. In this report, we demonstrate reconstitution of IkappaB kinase activity in vitro by using purified recombinant IKK1 and IKK2. Recombinant IKK1 or IKK2 forms homo- or heterodimers, suggesting the possibility that similar IKK complexes exist in vivo. Indeed, in HeLa cells we identified two distinct IKK complexes, one containing IKK1-IKK2 heterodimers and the other containing IKK2 homodimers, which display differing levels of activation following tumor necrosis factor alpha stimulation. To better elucidate the nature of the IKK signalsome, we set out to identify IKK-associated proteins. To this end, we purified and cloned a novel component common to both complexes, named IKK-associated protein 1 (IKKAP1). In vitro, IKKAP1 associated specifically with IKK2 but not IKK1. Functional analyses revealed that binding to IKK2 requires sequences contained within the N-terminal domain of IKKAP1. Mutant versions of IKKAP1, which either lack the N-terminal IKK2-binding domain or contain only the IKK2-binding domain, disrupt the NF-kappaB signal transduction pathway. IKKAP1 therefore appears to mediate an essential step of the NF-kappaB signal transduction cascade. Heterogeneity of IKK complexes in vivo may provide a mechanism for differential regulation of NF-kappaB activation.

Role of IKK1 and IKK2 in lipopolysaccharide signaling in human monocytic cells

Mononuclear phagocytes play a major role in immune and inflammatory responses. Bacterial lipopolysaccharide (LPS) induces monocytes to express a variety of genes by activating the NF-kappaB/Rel transcription factor family. Recently, we have reported that the tumor necrosis factor and interleukin 1 signaling pathways activate two kinases, IKK1 and IKK2. Phosphorylation of the IkappaB cytoplasmic inhibitors, IkappaBalpha, IkappaBbeta, and IkappaBepsilon, by these kinases triggers proteolytic degradation and the release of NF-kappaB/Rel proteins into the nucleus. At present, the role of the IKKs in LPS signaling has not been investigated. Here, we report that LPS induces IKK activity in human monocytes and THP-1 monocytic cells. The kinetics of activation of kinase activity in monocytic cells are relatively slow with maximal activity observed at 60 min, which coincides with the degradation of IkappaBs and the nuclear translocation of NF-kappaB. In transfection experiments, overexpression of wild type IKK1, a dominant negative mutant IKK1 (K44M), or wild type IKK2 did not affect LPS-induced kappaB-dependent transcription in monocytic cells. In contrast, a dominant negative mutant of IKK2 inhibited LPS induction of kappaB-dependent transcription in a dose-dependent manner. These results indicate that LPS induction of kappaB-dependent gene expression in human monocytic cells requires activation of IKK2.

Selective inhibition of TNF-alpha induced cell adhesion molecule gene expression by tanapox virus

Poxviruses encode virulence factors that have been identified as proteins that are secreted from infected host cells. Some of these secretory proteins impede host immune defences. We have previously demonstrated that tanapox virus (TPV) infected cells secrete an early 38 kDa glycopeptide that binds to human (h) interferon-gamma, hIL-2, and hIL-5. We now show an additional activity in the supernatant from TPV infected cells that down-regulates the expression of tumour necrosis factor-alpha (TNF-alpha) induced cell adhesion molecule gene expression. This activity was not detected in mock infected cells. Enzyme linked immunosorbent assays (ELISA) on primary human endothelial cells, show the induction of E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) following TNF-alpha or IL-1 beta treatment, as expected. Supernatant from TPV infected cells significantly decreased the TNF-alpha but not IL-1 beta-induced expression of these molecules. Mobility shift assays and Northern blot analyses further show that the supernatant from TPV infected cells inhibited TNF-alpha-induced activation of the nuclear transcription factor-kappa B (NF-kappa B) and transcriptional activation of the E-selectin, VCAM-1 and ICAM-1 genes. Based on TNF-alpha affinity chromatography, this activity appears to be associated with a 38 kDa glycopeptide.

IKK-1 and IKK-2: cytokine-activated IkappaB kinases essential for NF-kappaB activation

Activation of the transcription factor nuclear factor kappa B (NF-kappaB) is controlled by sequential phosphorylation, ubiquitination, and degradation of its inhibitory subunit IkappaB. A large multiprotein complex, the IkappaB kinase (IKK) signalsome, was purified from HeLa cells and found to contain a cytokine-inducible IkappaB kinase activity that phosphorylates IkappaB-alpha and IkappaB-beta. Two components of the IKK signalsome, IKK-1 and IKK-2, were identified as closely related protein serine kinases containing leucine zipper and helix-loop-helix protein interaction motifs. Mutant versions of IKK-2 had pronounced effects on RelA nuclear translocation and NF-kappaB-dependent reporter activity, consistent with a critical role for the IKK kinases in the NF-kappaB signaling pathway.

A model lightning safety policy for athletics

OBJECTIVE

The purpose of this paper is to present a model policy on lightning safety for athletic trainers.

BACKGROUND

Among college athletic programs in the United States there is a serious lack of written policy on lightning safety. Available evidence shows that most National Collegiate Athletic Association (NCAA) Division I institutions, even though they are located in high lightning activity areas of the country, do not have formal, written lightning safety policies.

CLINICAL ADVANTAGES/ RECOMMENDATIONS

The policy presented herein, which is at the forefront of such policies, is the lightning safety policy written as part of a policies and procedures manual for the division of sports medicine at a public NCAA Division I university. This is a policy based on practicality that utilizes the "flash-to- bang" method for determining the distance of lightning activity from the observer. The policy begins with the importance of prevention, including the daily monitoring of weather reports. The policy defines a "safe shelter" and specifies the chain of command for determining who removes a team or individuals from an athletic site in the event of dangerous lightning activity.

Glucose transport in a murine mammary epithelial cell line

The glucose transport systems of the COMMA-D cell line (a murine mammary epithelial cell line) were examined using 2-deoxyglucose as substrate. The kinetics and inhibition studies with other sugars including xylose suggested that the transport system had properties of both GLUT-1 and Glut-3. Subsequent analysis of mRNA transcripts using cDNAs for GLUT-1 to 4 showed that only GLUT-1 was expressed in the COMMA-D cells. The results highlight the fact that kinetic and substrate specificity are not sufficient, by themselves, for the identification and characterisation of GLUT isoforms in cultured cells.

Interleukin-4 suppression of tumor necrosis factor alpha-stimulated E-selectin gene transcription is mediated by STAT6 antagonism of NF-kappaB

Interleukin-4 (IL-4), an immunoregulatory cytokine secreted from activated T-helper 2 lymphocytes, eosinophils, and mast cells, stimulates the expression of a number of immune system genes via activation of the transcription factor, STAT6. However, IL-4 can concomitantly suppress the expression of other immune-related gene products, including kappa light chain, FcgammaRI, IL-8, and E-selectin. We demonstrate that IL-4 activates STAT6 in human vascular endothelial cells and that two STAT6 binding sites are present in the promoter of the E-selectin gene. IL-4-induced STAT6 binding does not activate E-selectin transcription but instead suppresses tumor necrosis factor alpha-induced expression of the E-selectin gene. STAT6 was found to compete for binding to a region in the E-selectin gene promoter containing overlapping STAT6 and NF-kappaB binding sites, effectively acting as an antagonist of NF-kappaB binding and transcriptional activation. This novel mechanism for IL-4-mediated inhibition of inflammatory gene expression provides an example of a STAT factor acting as a transcriptional repressor rather than an activator.

Persistence of supercompensated muscle glycogen in trained subjects after carbohydrate loading

Several carbohydrate (CHO)-loading protocols have been used to achieve muscle glycogen supercompensation and prolong endurance performance. This study assessed the persistence of muscle glycogen supercompensation over the 3 days after the supercompensation protocol. Trained male athletes completed a 6-day CHO-loading protocol that included cycle ergometer exercise and dietary manipulations. The 3-day depletion phase began with 115 min of cycling at 75% peak oxygen uptake followed by 3 x 60-s sprints and included the subjects consuming a low-CHO/high-protein/high-fat (10:41:49%) diet. Subjects cycled 40 min at the same intensity for the next 2 days. During the 3-day repletion phase, subjects rested and consumed a high-CHO/low-protein/low-fat (85:08:07%) diet, including a glucose-polymer beverage. A 3-day postloading phase followed, which involved a moderately high CHO diet (60%) and no exercise. Glycogen values for vastus lateralis biopsies at baseline and postloading days 1-3 were 408 +/- 168 (SD), 729 +/- 222, 648 +/- 186, and 714 +/- 196 mmol/kg dry wt, respectively. The CHO-loading protocol increased muscle glycogen by 1.79 times baseline, and muscle glycogen remained near this level during the 3-day postloading period. Results indicate that supercompensated muscle glycogen levels can be maintained for at least 3 days in a resting athlete when a moderate-CHO diet is consumed.

Identification of signal-induced IkappaB-alpha kinases in human endothelial cells

Activation of the nuclear transcription factor-kappaB is an early event in endothelial activation. NF-kappaB activation is regulated by the inducible phosphorylation and subsequent degradation of the inhibitory subunit IkappaB-alpha. We identified two discrete kinases of approximately 36 and 41 kDa in the cytoplasm of human umbilical vein endothelial cells that specifically bind to and phosphorylate the IkappaB-alpha subunit. IkappaB-alpha kinase activity is transiently elevated following treatment with either tumor necrosis factor alpha, interleukin-1beta, or bacterial lipopolysaccharides and precedes activation of either mitogen-activated kinase or Jun kinase. Furthermore, activation of the IkappaB-alpha kinases precedes both the appearance of hyperphosphorylated IkappaB-alpha and its subsequent degradation, as well as the translocation of NF-kappaB to the nucleus. Deletion mutagenesis of the IkappaB-alpha polypeptide revealed that these kinases bind in or around the ankyrin repeat domains and phosphorylate residues within the C terminus. These kinases, however, were not identical to casein kinase II and displayed a pharmacologic profile distinct from other known kinases. These kinases may represent components of a signal transduction pathway regulating IkappaB-alpha levels in vascular endothelium.

Isolation of cDNAs and tissue specific expression of ovine glucose transporters

The facilitative glucose transporters are a family of proteins responsible for the transmembrane transport of glucose and other hexose sugars (1,2). In mammals, the seven glucose transporter isoforms display a characteristic tissue distribution reflecting the physiological requirement and metabolism of glucose. This report describes the isolation and sequencing of the full length ovine GLUT-3 cDNA and the tissue distribution of ovine GLUT-1 and GLUT-3 mRNA. The ovine GLUT-3 cDNA is 3854 base pairs and the coding nucleotides show 82% and 79% homology with the human and mouse GLUT-3 sequences respectively. In addition, a reverse transcriptase-polymerase chain reaction strategy is described for the rapid isolation of mammalian cDNA subclones for GLUT-1, GLUT-2 and GLUT-4. This method has been used to isolate the corresponding ovine subclones.

Interaction between adrenergic and peptide stimulation in the rat pineal: pituitary adenylate cyclase-activating peptide

The 27 amino acid peptide, pituitary adenylate cyclase-activating polypeptide (PACAP-27), and its 38 amino acid analogue, PACAP-38, stimulate serotonin-N-acetyltransferase (NAT) activity and N-acetylserotonin (NAS) and melatonin content of pineal glands from adult rats. Maximal stimulation of rat pineal NAT by PACAP-38 is not increased further significantly by concurrent stimulation with the two related peptides, vasoactive intestinal polypeptide (VIP) and/or peptide N-terminal histidine C-terminal isoleucine (PHI). Isoproterenol was a more potent inducer of NAT activity than any of these peptides alone or in combination. PACAP-38 also stimulates melatonin production by chicken pineal cells in culture as does VIP. Stimulation by both was not greater than after either alone. Prior stimulation of rat pineal NAT activity with VIP, PHI, or PACAP-38 reduces the magnitude of subsequent stimulation with PACAP-38 or forskolin. Concurrent stimulation of alpha-receptors or treatment with active phorbol ester augments rat pineal response to PACAP-38 stimulation just as it increases the response to VIP, PHI, and beta-receptor stimulation. Pineals from newborn rats respond to PACAP-38 with an increase in NAT activity and the increase is augmented by concomitant alpha 1-adrenergic stimulation. The putative PACAP inhibitor PACAP (6-38) and the putative VIP inhibitor (Ac-Tyr,D-Phe)-GRF 1-29 amide, in 100-1,000-fold excess, did not affect the stimulatory activity of any of the peptides. Pineal melatonin concentration parallels changes in pineal NAT activity.