JNK Kinase Research Articles

Alternative splicing is coupled to gene expression in a subset of variably expressed genes

Numerous factors regulate alternative splicing of human genes at a co-transcriptional level. However, how alternative splicing depends on the regulation of gene expression is poorly understood. We leveraged data from the Genotype-Tissue Expression (GTEx) project to show a significant association of gene expression and splicing for 6874 (4.9%) of 141,043 exons in 1106 (13.3%) of 8314 genes with substantially variable expression in nine GTEx tissues. About half of these exons demonstrate higher inclusion with higher gene expression, and half demonstrate higher exclusion, with the observed direction of coupling being highly consistent across different tissues and in external datasets. The exons differ with respect to multiple characteristics and are enriched for hundreds of isoform-specific Gene Ontology annotations suggesting an important regulatory mechanism. Notably, splicing-expression coupling of exons with roles in JUN and MAP kinase signalling could play an important role during cell division.

β-Mangostin Alleviates Renal Tubulointerstitial Fibrosis via the TGF-β1/JNK Signaling Pathway.

The epithelial-to-mesenchymal transition (EMT) plays a key role in the pathogenesis of kidney fibrosis, and kidney fibrosis is associated with an adverse renal prognosis. Beta-mangostin (β-Mag) is a xanthone derivative obtained from mangosteens that is involved in the generation of antifibrotic and anti-oxidation effects. The purpose of this study was to examine the effects of β-Mag on renal tubulointerstitial fibrosis both in vivo and in vitro and the corresponding mechanisms involved. As shown through an in vivo study conducted on a unilateral ureteral obstruction mouse model, oral β-Mag administration, in a dose-dependent manner, caused a lesser degree of tubulointerstitial damage, diminished collagen I fiber deposition, and the depressed expression of fibrotic markers (collagen I, α-SMA) and EMT markers (N-cadherin, Vimentin, Snail, and Slug) in the UUO kidney tissues. The in vitro part of this research revealed that β-Mag, when co-treated with transforming growth factor-β1 (TGF-β1), decreased cell motility and downregulated the EMT (in relation to Vimentin, Snail, and N-cadherin) and phosphoryl-JNK1/2/Smad2/Smad3 expression. Furthermore, β-Mag co-treated with SB (Smad2/3 kinase inhibitor) or SP600125 (JNK kinase inhibitor) significantly inhibited the TGF-β1-associated downstream phosphorylation and activation of JNK1/2-mediated Smad2 targeting the Snail/Vimentin axis. To conclude, β-Mag protects against EMT and kidney fibrotic processes by mediating the TGF-β1/JNK/Smad2 targeting Snail-mediated Vimentin expression and may have therapeutic implications for renal tubulointerstitial fibrosis.

Alda-1 attenuation of binge alcohol-caused atrial arrhythmias through a novel mechanism of suppressed c-Jun N-terminal Kinase-2 activity

Holiday Heart Syndrome (HHS) is caused by excessive binge alcohol consumption, and atrial fibrillation (AF) is the most common arrhythmia among HHS patients. AF is associated with substantial morbidity and mortality, making its prevention and treatment of high clinical interest. This study defines the anti-AF action of Alda-1 (an established cardioprotective agent) and the underlying mechanisms of the action in our well-characterized HHS and cellular models. We found that Alda-1 effectively eliminated binge alcohol-evoked Ca2+ triggered activities (Ca2+ waves, prolonged Ca2+ transient diastolic decay) and arrhythmia inducibility in intact mouse atria. We then demonstrated that alcohol impaired human RyR2 channels (isolated from organ donors' hearts). The functional role of alcohol-caused RyR2 channel dysfunction in Ca2+ triggered arrhythmic activities was evidenced in a unique transgenic mouse model with a loss-of-function mutation (RyR2E4872Q+/−). Alda-1 is known to activate aldehyde dehydrogenase 2 (ALDH2), a key enzyme in alcohol detoxification. However, we found an increased level of ALDH2 and a preserved normal balance of pro- vs anti-apoptotic signaling in binge alcohol exposed hearts and H9c2 differentiated myocytes, which suggests that the link of alcohol-ALDH2-apoptosis is unlikely to be a key factor leading to binge alcohol-evoked arrhythmogenicity. We have previously reported that binge alcohol-activated stress response kinase JNK2 causatively drives Ca2+-triggered atrial arrhythmogenicity. Here, we found that JNK2-specific inhibition in either isolated human RyR2 channels or intact mouse atria abolished alcohol-evoked RyR2 channel dysfunction and Ca2+ triggered arrhythmic activities, suggesting a strong alcohol-JNK2-RyR2 interaction in atrial arrhythmogenicity. Furthermore, we revealed, for the first time, that Alda-1 suppresses JNK2 (but not JNK1) enzyme activity independently of ALDH2, which in turn alleviates binge alcohol-evoked Ca2+ triggered atrial arrhythmogenesis. Our findings provide novel mechanistic insights into the anti-arrhythmic action of Alda-1 and suggest that Alda-1 represents a potential preventative agent for AF management for HHS patients.

Development of Novel 1,3,4‐Trisubstituted Pyrazole Derivatives Bearing Sulfonamide Moiety as Anticancer Agents Targeting JNK Kinases

AbstractIn the present work, a new set of N‐(2‐((4‐(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)pyridine sulfonamide derivatives was synthesized. Final target compounds were tested against JNK1 and JNK2 isoforms. Compounds 8f and 8d showed the highest activity over both JNK isoforms. They showed submicromolar activity over JNK1 (IC50 0.90 µM and 0.96 µM, respectively). They also showed excellent activity over JNK2 (IC50 0.62 µM and 1.07 µM, respectively). Moreover, the final target compounds were tested over HL‐60 and K‐562 cell lines for assessing the in vitro anticancer activity using sorafenib as a positive control. Compound 8f showed the highest potency at IC50 values of 6.21 and 7.43 µM, respectively. Furthermore, compounds 8e and 8g exhibited strong effects on both acute leukemia cancer cell lines with IC50 values of 13.83 and 10.02 µM, respectively, as well as chronic leukemia cancer cell line with IC50 of 12.65 and 9.51 µM, respectively. Compound 8f was also tested to examine its effect on the cell cycle. Finally, a molecular docking study was conducted to understand the plausible binding modes of the most active compounds 8d and 8f within the JNK1 and JNK2 binding sites.

Novel N-Substituted Isatin-Oxoindolin-1H-Benzo[D] Imidazole Fumarate as a New Class of JNK3 Inhibitor: Design, Synthesis, Molecular Modeling and its Biological Activity

Background: A direct synthesis of functionalized dimethyl fumarate derivatives of 2-(2-((E)-(2-oxoindolin-3-ylidene)methyl)-1H-benzo[d]imidazol-1-yl) is achieved via one-pot reac-tion involving 2-methyl-1H-benzo[d]imidazole and appropriate isatin in the presence of DMAD. Methods: Conversely, this one-pot reaction furnished, upon conduction at 60 o C, the 2-(2-((E)-(2-oxoindolin-3-ylidene)methyl)-1H-benzo[d]imidazol-1-yl) products. The biological activities were evaluated against JNK3 kinase. We chose to dock the compounds into the JNK3 binding site in order to comprehend the molecular underpinnings of the observed bioactivities. Results: The structures of the synthesized compound adduct were evidenced from NMR and MS spectral data and further confirmed by single-crystal X-ray diffraction. The biological activities revealing that the introduction of an alkyl group at the 1-position of the isatin moiety produced JNK3 inhibitors with IC50 values in the low micromolar range. Conclusion: This study synthesized a unique compound using a three-component method. Com-pound 4d showed high antitumor activity (IC50 = 6.5 μM) against JNK3 inhibitors, while com-pounds 4c, 4d, and 4f exhibited high selectivity. The research highlights the effectiveness of the one-pot reaction in creating medically useful hybrid compounds, marking a significant advance in medicinal chemistry.

JNK Kinase regulates cachexia like syndrome in scribble knockdown tumor model of Drosophila melanogaster

Cachexia and systemic organ wasting are metabolic syndrome often associated with cancer. However, the exact mechanism of cancer associated cachexia like syndrome still remain elusive. In this study, we utilized a scribble (scrib) knockdown induced hindgut tumor to investigate the role of JNK kinase in cachexia like syndrome. Scrib, a cell polarity regulator, also acts as a tumor suppressor gene. Its loss and mis-localization are reported in various type of malignant cancer-like breast, colon and prostate cancer. The scrib knockdown flies exhibited male lethality, reduced life span, systemic organ wasting and increased pJNK level in hindgut of female flies. Interestingly, knocking down of human JNK Kinase analogue, hep, in scrib knockdown background in hindgut leads to restoration of loss of scrib mediated lethality and systemic organ wasting. Our data showed that scrib loss in hindgut is capable of inducing cancer associated cachexia like syndrome. Here, we firstly report that blocking the JNK signaling pathway effectively rescued the cancer cachexia induced by scrib knockdown, along with its associated gut barrier disruption. These findings have significantly advanced our understanding of cancer cachexia and have potential implications for the development of therapeutic strategies. However, more research is needed to fully understand the complex mechanisms underlying this condition.

Comprehensive Phytochemical Profiling, GC-MS Analysis, Molecular Docking and Antiproliferative Activity of Ethanol Fraction of <i>Tabernaemontana coronaria</i> and <i>Thunbergia alata</i>

Objective: Current study involves the phytochemical examination, GC MS testing of ethanol fraction of leaves of two plants Tabernaemontana coronaria and Thunbergia alata. Methods: Both ethanol fractions of selected plants were subjected to In vitro antiproliferative activity by employing MTT assay on A549 cell lines. Zebra Fish fin model and zebra fish embryo tests were employed to assess the fin regeneration and effect on angiogenesis respectively. Results: The phytochemical screening discovered existence of terpenoids, proteins, carbohydrates, phenols, tannins, saponins, flavonoids, glycosides, and alkaloids in both T. coronaria and T. alata. The GC MS profile of the ethanol portion of T. coronaria leaves identified 16 components, while the ethanol fraction of T. alata leaves had 14 components. The molecular docking experiments showed that compound 1 and compound 4 had favorable docking energies of -8.7 kcal.mol-1and -8.2 kcal.mol-1, correspondingly, in the site of JNK-1 kinase. Compound 4 established hydrogen bond interactions with Ser34 and Asp169 in the catalytic and DFG motif regions of the JNK-1, respectively. Compounds 3 and 7, with docking energies of -6.4 and -7.9 kcal.mol-1, correspondingly, also resided in active motif of JNK-1. Compound 2 had docking energy of -5.4 kcal.mol-1 and was well placed in the protein cavity. Regarding the binding of compounds in the KAS III, compound 4 had an excellent docking energy of -8.0kcal.mol-1, and compound 2 had docking energy -5.9 kcal.mol-1. Both compounds were well placed in the active pocket of KAS III macromolecule and established hydrogen bond interactions with Asn260 and Arg262. Compound 4 also established hydrophobic contacts with Arg46 and Arg223. Conclusion: The study states that T. coronaria and T. alata treatment strongly inhibited A549 cells viability, and cell volume expansion, which result in cell proliferation. Likewise, a noteworthy decrease in fin regeneration and reduction in percentage vessel growth was observed in zebra fish and embryo assays.

Abstract Tu074: A Potential Link Between Stress Kinase JNK2 and AKAP-1 in Catecholamine-Induced Acute Heart Failure

Takotsuba Syndrome (TTS) is a type of emotional/physical stress-induced heart failure (HF). Stress-elevated catecholamines activate adrenergic signaling. Cardiac A-Kinase Anchoring Protein-1 (AKAP1) is known to regulate the adrenergic signaling via protein complex formation and phosphorylation. We recently discovered that activation of the stress response kinase JNK2 is critical in HF onset. Whether AKAP1 is involved with stress-activated JNK2 and HF onset remains completely unknown. Isoproterenol (Iso; synthetic catecholamine) effects on JNK2 activation were assessed in left ventricles (LV) from Iso-treated wildtype (WT) mice (67 mg/kg i.p., 2 days) and in heterologous HEK-RyR2 cells (inducible cardiac ryanodine receptor-2; myocyte mimic; 5 mM Iso, 24 h). A JNK2 effect on cardiac function was reflected by cardiac output (CO) using echocardiography in cardiac-specific MKK7D (inducible overexpression of active MKK7D; a JNK upstream activator) and MKK7D-JNK2KD (50% JNK2 knockdown in MKK7D) mice. The AKAP1-JNK2 link was assessed using immunoprecipitation (IP) and immunoblotting in tGFP -JNK2 and/or FLAG -AKAP1 transfected HEK293 cells. Iso-WT LV had increased JNK phosphorylation (JNK-p, activated) and reduced SERCA2 (a hallmark of HF) vs controls. Likely, MKK7-induction in MKK7D LV increased JNK2 and JNK-p (vs WT-littermates; p<0.05, n=5,4), which led to reduced CO by 68% (n=5,6, p<0.01) and downregulated SERCA2 by 79% (p<0.01, n=4,8), also evidenced by preserved CO and SERCA2 in MKK7D-JNK2KD mice (50% ablated JNK2; n=9). Moreover, Iso treatment in HEK-RyR2 cells activated JNK2, but not JNK1, compared to sham controls. Intriguingly, we found that JNK2 was associated with AKAP1, given the co-IP of tGFP -JNK2 with anti- FLAG antibody pulldown of FLAG -AKAP1 co-transfected HEK293 cells (n=3). Further, overexpressed FLAG -AKAP1 increased the phosphorylation of co-transfected tGFP -JNK2 as well as endogenous JNK (p<0.01 & p<0.001, n=3,3), while the notable JNK downstream target c-Jun also showed increased phosphorylation (c-Jun-p; p<0.05, n=3,3), supporting a previously unrecognized role for AKAP1 in JNK2 activation. In total, our findings suggest that stress activates JNK2 via an adrenergic-AKAP1 activation pathway to drive HF/TTS onset.

Abstract Or117: JNK2-mediated gut-heart crosstalk in aging-associated AF pathogenesis.

Introduction: Aging is an independent risk factor for atrial fibrillation (AF). We recently revealed a critical role of activated cardiac stress kinase JNK2 in AF risk. Yet, the mechanisms underlying JNK2 activation in the aged heart remain unclear. Emerging evidence suggests that organ crosstalk critically contributes to the development of heart diseases. Interestingly, increased AF episodes were clinically observed in patients with active gastrointestinal (GI) diseases (with a hallmark of enhanced intestinal epithelial barrier permeability (‘leaky gut’), but reduced AF during remission. While both GI dysfunction and enhanced AF risk are seen in aged humans and animal models, whether aging-associated leaky gut leads to AF pathogenesis through activated JNK2 remains unknown. Methods: To assess the leaky gut and AF link, young (Yg, 2 mo) wildtype (WT) and JNK2dn mice (cardiac-specific overexpression of inactive dominant negative (dn) JNK2) were used for aged fecal matter transplant (FMT), while aged (Ag, 24 mo) mice were transplanted with Yg fecal matter to rescue aging-associated AF. Atrial tachycardia/fibrillation (AT/AF) incidence was measured using our well-established protocol, and GI permeability was measured using a serum dextran (4-kDa) FITC fluorescence assay 7 days post-FMT. Results: Aged WT mice had an elevated FITC level (4.9±1.5 µg/ml vs 0.98±0.04 µg/ml; n=11,8; p<0.01) with increased AT/AF inducibility compared to Yg mice (n=7,10; p<0.05). Interestingly, Yg WT recipients subjected to aged FMT (Ag-to-Yg) exhibited an ~3-fold increase in GI permeability (n=14; p<0.01) and significantly enhanced AT/AF inducibility relative to Yg sham controls (8 of 13 vs 0 of 10; p<0.05), while Yg-to-Yg FMT did not alter GI permeability and AT/AF inducibility in Yg recipients (0 of 5, p=NS). Strikingly, cardiac-specific JNK2 inhibition prevented aged-FMT-caused AT/AF in Yg JNK2dn recipient mice (0 of 10; p<0.01), suggesting that activated cardiac JNK2 underlies leaky gut-evoked AF in aging. Further, Yg-to-Ag FMT eliminated aged-associated AT/AF inducibility in aged recipients (0 of 6). Conclusion: Aging-associated GI dysfunction enhances cardiac JNK2 activation, which in turn drives AF risk. Targeting cardiac JNK2 could be a novel anti-AF therapeutic strategy.

Abstract Tu040: A Novel Anti-Thrombotic and Anti-AF Drug without an Adverse Bleeding Problem

Introduction: Aging is an independent risk factor of atrial fibrillation (AF), which leads to a high mortality due to thromboembolic stroke. But available antithrombotic therapies are limited for the aged AF patients due to aging-associated bleeding risk. We recently revealed critical roles of activated cardiac stress kinase JNK2 in both enhanced AF risk and thrombogenesis in aging through a mechanism of heart-platelet crosstalk. Here, we assessed anti-thrombotic potentials of JNK2 inhibition. Methods: Young (Yg) and aged (2 vs 24 mo) wildtype (WT) mice with and without a JNK2-specific inhibitor (JNK2I, 5 mg/kg i.p.; every other day/4 doses) or meloxicam (0.5 mg/kg/day, i.p.; five days) treatment were used for in vivo FeCl 3 -induced carotid artery occlusion (thrombus formation) and tail bleeding assays. The effects of cardiac JNK2-specific inhibition in thrombogenesis and bleeding were assessed in our unique cardiac-specific mice of MKK7D (inducible overexpression of active MKK7D, a JNK upstream activator) and MKK7D-JNK2dn (overexpressed inactive dominant negative (dn) JNK2 to competitively inhibit endogenous JNK2 in MKK7D mice). Results: Aged mice had a shortened artery occlusion time compared to Yg (5.8±0.2 min vs. 7.1±0.2 min, p<0.001, n=12,7). JNK2I reversed the occlusion time in aged mice to that seen in Yg (p=NS, n=8,7). Yg MKK7D mice also showed a shortened occlusion time compared to WT-controls (p<0.001, n=9,8) that was rescued by cardiac-specific JNK2 inhibition in MKK-JNK2dn mice (p=NS, n=5,8), suggesting a key role of cardiac JNK2 in thrombus formation. Next, we found that 40% of aged WT mice had continuous bleeding compared to its absence in Yg WT. However, meloxicam (an anti-platelet NSAID drug) increased continuous bleeding risk in both aged (83% had it) and Yg (20%) and prolonged the initial clotting time in aged mice (385±56s vs 84±18s in aged controls; p<0.001, n=8,6). In contrast, JNK2I eliminated this bleeding issue, evidenced from the absence of continuous bleeding and shortened initial clotting time compared to aged controls (p=NS, n=8,8). Conclusion: Heart JNK2 enhances thrombotic risk in the blood. JNK2 inhibition could be a promising anti-thrombotic and anti-AF therapeutic approach without adverse bleeding for aged AF patients.

Abstract Mo065: An Anti-arrhythmic Action and Novel Molecular Mechanisms of Alda-1 in Holiday Heart Syndrome

Introduction: Holiday Heart Syndrome (HHS) is caused by excessive binge alcohol intake. Atrial fibrillation (AF) is the most common arrhythmia in HHS patients. With a worldwide rising trend in heavy alcohol consumption despite significant prevention efforts, effective drugs against alcohol-evoked AF are in urgent need. Methods: We assessed the effect of Alda-1, a cardiac protective agent, on mitigating binge alcohol-evoked AF and alcohol-activated stress kinase JNK2 in 50mM alcohol-exposed (24hr) H9c2 differentiated myocytes and in a well-characterized HHS mouse model (2g/kg ethanol i.p., 4 injections, every other day). Alda-1’s effect on alcohol-evoked RyR2 channel-mediated Ca 2+ waves/sparks & tachycardia/fibrillation (AT/AF) incidence were measured in intact mouse atria. RyR2 channel open probability was assessed in human RyR2 single-channel recordings. Results: We found that Alda-1 significantly reduced atrial arrhythmia inducibility in HHS mouse atria, as evidenced by a decreased incidence of alcohol-evoked AT/AF (0 vs. 0.21 incidences/pacing attempts/animal; n=6, 8). Alda-1 is an agonist of aldehyde dehydrogenase 2 (ALDH2; a key enzyme in alcohol detoxification), which inhibits cellular apoptosis. We found that ALDH2 was increased by 42%±6 in HHS mice compared to controls, and which remained elevated upon Alda-1 treatment (n=6,7,7; p<0.05). HHS hearts showed unchanged apoptotic signaling pathways, suggesting alternative mechanisms in AF genesis. Our lab recently revealed a critical role of activated cardiac stress kinase JNK2 in AF risk. Intriguingly, Alda-1 suppressed alcohol-activated JNK2 by 70%±13 (immunoprecipitated JNK2-specific activity; n=9,9, p<0.001) (but not JNK1, the other cardiac JNK isoform) in cells, while JNK2 inhibition alleviated alcohol-evoked RyR2 channel dysfunction in human RyR2 channels as well as Ca 2+ -triggered atrial arrhythmic activities and AT/AF (0 out of 8; p<0.05) in intact mouse hearts. Conclusion: Alda-1 effectively mitigates binge alcohol-evoked atrial arrhythmogenesis by suppressing JNK2 activity independently of an ALDH2-mediated anti-apoptosis effect. Our findings highlight the potential of Alda-1 as a therapeutic agent for the increasing incidence of alcohol-evoked AF.

New substituted benzoxazine derivatives as potent inducers of membrane permeability and cell death

The search for new agents targeting different forms of cell death is an important research focus for developing new and potent antitumor therapies. As a contribution to this endeavor, we have designed and synthesized a series of new substituted 3,4-dihydro-2H-1,4-benzoxazine derivatives. These compounds have been evaluated for their efficacy against MCF-7 breast cancer and HCT-116 colon cancer cell lines. Overall, substituting this heterocycle led to improved antiproliferative activity compared to the unsubstituted derivative 1. The most active compounds, 2b and 4b, showed IC50 values of 2.27 and 3.26 μM against MCF-7 cells and 4.44 and 7.63 μM against HCT-116 cells, respectively. To investigate the mechanism of action of the target compounds, the inhibition profile of 8 kinases involved in cell signaling was studied highlighting residual activity on HER2 and JNK1 kinases. 2b and 4b showed a consistent binding mode to both receptor kinases, establishing significant interactions with known and catalytically important domains and residues. Compounds 2b and 4b exhibit potent cytotoxic activity by disrupting cell membrane permeability, likely triggering both inflammatory and non-inflammatory cell death mechanisms. This dual capability increases their versatility in the treatment of different stages or types of tumors, providing greater flexibility in clinical applications.

Neuroprotective Effects of Metformin on Cerebral Ischemia-Reperfusion Injury: Modulation of JNK and p38 MAP Kinase Signaling Pathways.

Cerebral ischemia-reperfusion injury (CIRI) is a significant pathological process in stroke, characterized by neuronal cell death and neurological dysfunction. Metformin, commonly used for diabetes management, has been noted for its neuroprotective properties, though its effects on CIRI and the mechanisms involved remain unclear. This study explored the neuroprotective impact of metformin on CIRI, focusing on its potential to modulate the c-Jun N-terminal kinase (JNK) and p38 MAP kinase (p38) signaling pathways. Using in vitro models of oxygen-glucose deprivation/reperfusion (OGD/R) in neuronal cells and in vivo mouse models of middle cerebral artery occlusion (MCAO), the effects of metformin were assessed. Cell viability was measured with Cell Counting Kit-8 (CCK-8), protein expression via Western Blot (WB), and apoptosis through flow cytometry. The extent of brain injury in mice was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining, while JNK and p38 activation statuses were detected through WB and phospho-JNK (p-JNK) immunofluorescence staining. Results showed that metformin significantly improved the viability of HT22 cells post-OGD/R, reduced apoptosis, and decreased OGD/R-induced phosphorylation of JNK and p38 in vitro. In vivo, metformin treatment notably reduced brain infarct volume in MCAO mice, inhibited p-p38 and p-JNK expression, and enhanced neurological function. These findings suggest that metformin exerts neuroprotective effects against CIRI by modulating the JNK/p38 signaling pathway, highlighting its potential therapeutic value in treating cerebral ischemia-reperfusion injury and paving the way for clinical applications.

IL-1β-Induced CXCL10 Expression in THP-1 Monocytic Cells Involves the JNK/c-Jun and NF-κB-Mediated Signaling.

CXCL10 (IP-10) plays a key role in leukocyte homing to the inflamed tissues and its increased levels are associated with the pathophysiology of various inflammatory diseases including obesity and type 2 diabetes. IL-1β is a key proinflammatory cytokine that is found upregulated in meta-inflammatory conditions and acts as a potent activator, inducing the expression of cytokines/chemokines by immune cells. However, it is unclear whether IL-1β induces the expression of CXCL10 in monocytic cells. We, therefore, determined the CXCL10 induction using IL-1β in THP1 monocytic cells and investigated the mechanisms involved. Monocytes (human monocytic THP-1 cells) were stimulated with IL-1β. CXCL10 gene expression was determined with real-time RT-PCR. CXCL10 protein was determined using ELISA. Signaling pathways were identified by using Western blotting, inhibitors, siRNA transfections, and kinase assay. Our data show that IL-1β induced the CXCL10 expression at both mRNA and protein levels in monocytic cells (p = 0.0001). Notably, only the JNK inhibitor (SP600125) significantly suppressed the IL-1β-induced CXCL10 expression, while the inhibitors of MEK1/2 (U0126), ERK1/2 (PD98059), and p38 MAPK (SB203580) had no significant effect. Furthermore, IL-1β-induced CXCL10 expression was decreased in monocytic cells deficient in JNK/c-Jun. Accordingly, inhibiting the JNK kinase activity markedly reduced the IL-1β-induced JNK/c-Jun phosphorylation in monocytic cells. NF-κB inhibition by Bay-117085 and resveratrol also suppressed the CXCL10 expression. Our findings provide preliminary evidence that IL-1β stimulation induces the expression of CXCL10 in monocytic cells which requires signaling via the JNK/c-Jun/NF-κB axis.

The Role and Efficacy of JNK Inhibition in Inducing Lung Cancer Cell Death Depend on the Concentration of Cisplatin.

Toxicity and the emergence of resistance are the main challenges in cancer treatment. The optimal dose of cisplatin, one of the most widely used chemotherapeutic anticancer drugs, is currently being widely debated. Furthermore, the dose-dependent molecular mechanisms of its action are poorly understood. To assess the role of protein kinase JNK (cJun N-terminal kinase) signaling in lung cancer treatment, we combined small-molecule JNK inhibitors and cisplatin. Wild-type p53 (tumor suppressor transcription factor TP53) and mutated RAS-bearing lung adenocarcinoma cell line A549 was used as a model in our studies. Here, we demonstrate cisplatin concentration-dependent opposing roles of JNK in killing cancer cells: a cell-protective role at low cisplatin concentrations and an apoptosis-promoting (or neutral) role at high concentrations. Time- and dose-dependent activation of pro-survival protein kinase AKT and TP53 was shown, with similar activation dynamics in cells exposed to different (low and high) cisplatin concentrations. Selective inhibition of AKT and activation of TP53 (expression and phosphorylation) led to a decrease in cell survival, indicating their involvement in cisplatin-induced cell death regulation. The activation levels of TP53 and AKT in cisplatin-treated A549 cells after cotreatment with the JNK inhibitor SP600125 correlated with their role in regulating cell death. TP53 and AKT were proposed as signaling proteins mediating the outcome of JNK inhibition in A549 cells exposed to different concentrations of cisplatin. Our findings suggest that a combination of stress kinase JNK inhibition and low-dose cisplatin, together with manipulation of drug-induced signaling, could be considered as a promising treatment strategy for certain lung cancers.

DUSP8 Promotes IL-9 Transcription by Inactivating Pur-α leading to asthma and atopic dermatitis

Abstract Dual-specificity phosphatase 8 (DUSP8) is a member of the DUSP family. DUSP8 dephosphorylates and inactivates the kinase JNK. DUSP8 protein levels are predominantly expressed in CD4+ T cells and platelets. DUSP8 dephosphorylates and inactivates specifically JNK in Jurkat T cells; however, the in vivo role of DUSP8 in T cells remains unclear. Using T-cell-specific DUSP8 conditional knockout (T-DUSP8 cKO, DUSP8f/f;CD4-Cre) mice, mass spectrometry, and chromatin-immunoprecipitation sequencing, we found that DUSP8 stimulated IL-9 gene expression and Th9 differentiation. TGF-β stimulated DUSP8 phosphatase activity in T cells. Mechanistically, DUSP8 dephosphorylated the transcriptional repressor Pur-α upon TGF-β signaling, leading to the nuclear export of Pur-α and subsequent IL-9 transcriptional activation. Furthermore, Il-9 mRNA levels in murine T cells were induced in Pur-α knockout. Reduction of IL-9 levels in T cells of T-DUSP8 cKO mice was reversed by Pur-α heterozygous knockout. Consistently, T-DUSP8 cKO mice displayed reduction of IL-9 and Th9-mediated immune responses in allergy, autoimmune responses, and anti-tumor immunity. Remarkably, DUSP8 overexpression and DUSP8-Pur-α interaction indeed occurred in the peripheral blood T cells of patients with asthma or atopic dermatitis, contributing to IL-9 overproduction in patients’ T cells. Thus, DUSP8 plays a critical role in the pathogenesis of asthma and atopic dermatitis, as well as autoimmune disease and cancer.

Hepatic Sirt6 activation abrogates acute liver failure.

Acute liver failure (ALF) is a deadly illness due to insufficient detoxification in liver induced by drugs, toxins, and other etiologies, and the effective treatment for ALF is very limited. Among the drug-induced ALF, acetaminophen (APAP) overdose is the most common cause. However, the molecular mechanisms underlying APAP hepatoxicity remain incompletely understood. Sirtuin 6 (Sirt6) is a stress responsive protein deacetylase and plays an important role in regulation of DNA repair, genomic stability, oxidative stress, and inflammation. Here, we report that genetic and pharmacological activation of Sirt6 protects against ALF in mice. We first observed that Sirt6 expression was significantly reduced in the liver tissues of human patients with ALF and mice treated with an overdose of APAP. Then we developed an inducible Sirt6 transgenic mice for Cre-mediated overexpression of the human Sirt6 gene in systemic (Sirt6-Tg) and hepatic-specific (Sirt6-HepTg) manners. Both Sirt6-Tg mice and Sirt6-HepTg mice exhibited the significant protection against APAP hepatoxicity. In contrast, hepatic-specific Sirt6 knockout mice exaggerated APAP-induced liver damages. Mechanistically, Sirt6 attenuated APAP-induced hepatocyte necrosis and apoptosis through downregulation of oxidative stress, inflammation, the stress-activated kinase JNK activation, and apoptotic caspase activation. Moreover, Sirt6 negatively modulated the level and activity of poly (ADP-ribose) polymerase 1 (PARP1) in APAP-treated mouse liver tissues. Importantly, the specific Sirt6 activator MDL-800 exhibited better therapeutic potential for APAP hepatoxicity than the current drug acetylcysteine. Furthermore, in the model of bile duct ligation induced ALF, hepatic Sirt6-KO exacerbated, but Sirt6-HepTg mitigated liver damage. Collectively, our results demonstrate that Sirt6 protects against ALF and suggest that targeting Sirt6 activation could be a new therapeutic strategy to alleviate ALF.

The Wingless planar cell polarity pathway is essential for optimal activity-dependent synaptic plasticity.

From fly to man, the Wingless (Wg)/Wnt signaling molecule is essential for both the stability and plasticity of the nervous system. The Drosophila neuromuscular junction (NMJ) has proven to be a useful system for deciphering the role of Wg in directing activity-dependent synaptic plasticity (ADSP), which, in the motoneuron, has been shown to be dependent on both the canonical and the noncanonical calcium Wg pathways. Here we show that the noncanonical planar cell polarity (PCP) pathway is an essential component of the Wg signaling system controlling plasticity at the motoneuron synapse. We present evidence that disturbing the PCP pathway leads to a perturbation in ADSP. We first show that a PCP-specific allele of disheveled (dsh) affects the de novo synaptic structures produced during ADSP. We then show that the Rho GTPases downstream of Dsh in the PCP pathway are also involved in regulating the morphological changes that take place after repeated stimulation. Finally, we show that Jun kinase is essential for this phenomenon, whereas we found no indication of the involvement of the transcription factor complex AP1 (Jun/Fos). This work shows the involvement of the neuronal PCP signaling pathway in supporting ADSP. Because we find that AP1 mutants can perform ADSP adequately, we hypothesize that, upon Wg activation, the Rho GTPases and Jun kinase are involved locally at the synapse, in instructing cytoskeletal dynamics responsible for the appearance of the morphological changes occurring during ADSP.

Unveiling the signaling network of FLT3-ITD AML improves drug sensitivity prediction.

Currently, the identification of patient-specific therapies in cancer is mainly informed by personalized genomic analysis. In the setting of acute myeloid leukemia (AML), patient-drug treatment matching fails in a subset of patients harboring atypical internal tandem duplications (ITDs) in the tyrosine kinase domain of the FLT3 gene. To address this unmet medical need, here we develop a systems-based strategy that integrates multiparametric analysis of crucial signaling pathways, and patient-specific genomic and transcriptomic data with a prior knowledge signaling network using a Boolean-based formalism. By this approach, we derive personalized predictive models describing the signaling landscape of AML FLT3-ITD positive cell lines and patients. These models enable us to derive mechanistic insight into drug resistance mechanisms and suggest novel opportunities for combinatorial treatments. Interestingly, our analysis reveals that the JNK kinase pathway plays a crucial role in the tyrosine kinase inhibitor response of FLT3-ITD cells through cell cycle regulation. Finally, our work shows that patient-specific logic models have the potential to inform precision medicine approaches.

Deregulated JNK signaling enhances apoptosis during hyperthermia

Purpose c-Jun N-terminal kinases (JNKs) comprise a subfamily of mitogen-activated protein kinases (MAPKs). The JNK group is known to be activated by a variety of stimuli. However, the molecular mechanism underlying heat-induced JNK activation is largely unknown. The aim of this study was to clarify how JNK activity is stimulated by heat. Methods and materials The expression levels of various MAPK members in HeLa cells, with or without hyperthermia treatment, were evaluated via western blotting. The kinase activity of MAPK members was assessed through in vitro kinase assays. Cell death was assessed in the absence or presence of siRNAs targeting MAPK-related members. Results Hyperthermia decreased the levels of MAP3Ks, such as ASK1 and MLK3 which are JNK kinase kinase members, but not those of the downstream MAP2K/SEK1 and MAPK/JNK. Despite the reduced or transient phosphorylation of ASK1, MLK3, or SEK1, downstream JNK was phosphorylated in a temperature-dependent manner. In vitro kinase assays demonstrated that heat did not directly stimulate SEK1 or JNK. However, the expression levels of DUSP16, a JNK phosphatase, were decreased upon hyperthermia treatment. DUSP16 knockdown enhanced the heat-induced activation of ASK1–SEK1–JNK pathway and apoptosis. Conclusion JNK was activated in a temperature-dependent manner despite reduced or transient phosphorylation of the upstream MAP3K and MAP2K. Hyperthermia-induced degradation of DUSP16 may induce activation of the ASK1–SEK1–JNK pathway and subsequent apoptosis.