Expression Of Apoptosis Signal-regulating Kinase 1 Research Articles

ASK1-mediated Apoptosis in Human Lung Fibroblasts

Idiopathic pulmonary fibrosis (IPF) is a chronic, devastating lung disease characterized by progressive fibrosis and dysregulated wound repair that negatively affect lung function. Although lung fibroblasts are important in repair mechanisms following lung injury, differentiation into myofibroblasts in the presence of TGF-β and resistance to apoptosis can promote the progression of pulmonary fibrosis. Apoptosis signal regulating kinase 1 (ASK1) is a member of the mitogen activated protein (MAP) kinase family that is known to promote apoptosis. The objective of this study was to test the hypothesis that ASK1 is an important mediator of apoptosis in lung fibroblasts. Normal human lung fibroblasts were obtained from five donors and cultured in the presence or absence of TGF-β (1ng/mL) for 72h. Apoptosis was assessed by a Caspase-Glo® 3/7 assay following treatment with a combination of cycloheximide and Fas ligand antibody with or without the ASK1 inhibitor, selonsertib. Expression of α-smooth muscle actin (α-SMA), collagen, ASK1, and survivin (a member of the inhibitor of apoptosis protein family) were determined by western blot. Apoptosis was induced in three of the five donor lines, and selonsertib treatment reduced caspase-3/7 activity. These donor lines expressed lower levels of survivin compared with the non-responding lines. TGF-β did not significantly affect these results. As expected, TGF-β stimulated expression of collagen and α-SMA in all donor lines, but this was reduced by treatment with selonsertib. Interestingly, TGF-β caused a reduction in the expression of ASK1 which is consistent with the idea that myofibroblasts in IPF are resistant to apoptosis. These results suggest that ASK1 can promote apoptosis in normal lung fibroblasts, but this is dependent upon the expression of survivin. Supported by VA Merit Award BX005889 (CMW) and NIH grant HL131526 (CMW). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

ASK1-K716R reduces neuroinflammation and white matter injury via preserving blood–brain barrier integrity after traumatic brain injury

BackgroundTraumatic brain injury (TBI) is a significant worldwide public health concern that necessitates attention. Apoptosis signal-regulating kinase 1 (ASK1), a key player in various central nervous system (CNS) diseases, has garnered interest for its potential neuroprotective effects against ischemic stroke and epilepsy when deleted. Nonetheless, the specific impact of ASK1 on TBI and its underlying mechanisms remain elusive. Notably, mutation of ATP-binding sites, such as lysine residues, can lead to catalytic inactivation of ASK1. To address these knowledge gaps, we generated transgenic mice harboring a site-specific mutant ASK1 Map3k5-e (K716R), enabling us to assess its effects and elucidate potential underlying mechanisms following TBI.MethodsWe employed the CRIPR/Cas9 system to generate a transgenic mouse model carrying the ASK1-K716R mutation, aming to investigate the functional implications of this specific mutant. The controlled cortical impact method was utilized to induce TBI. Expression and distribution of ASK1 were detected through Western blotting and immunofluorescence staining, respectively. The ASK1 kinase activity after TBI was detected by a specific ASK1 kinase activity kit. Cerebral microvessels were isolated by gradient centrifugation using dextran. Immunofluorescence staining was performed to evaluate blood–brain barrier (BBB) damage. BBB ultrastructure was visualized using transmission electron microscopy, while the expression levels of endothelial tight junction proteins and ASK1 signaling pathway proteins was detected by Western blotting. To investigate TBI-induced neuroinflammation, we conducted immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR) and flow cytometry analyses. Additionally, immunofluorescence staining and electrophysiological compound action potentials were conducted to evaluate gray and white matter injury. Finally, sensorimotor function and cognitive function were assessed by a battery of behavioral tests.ResultsThe activity of ASK1-K716R was significantly decreased following TBI. Western blotting confirmed that ASK1-K716R effectively inhibited the phosphorylation of ASK1, JNKs, and p38 in response to TBI. Additionally, ASK1-K716R demonstrated a protective function in maintaining BBB integrity by suppressing ASK1/JNKs activity in endothelial cells, thereby reducing the degradation of tight junction proteins following TBI. Besides, ASK1-K716R effectively suppressed the infiltration of peripheral immune cells into the brain parenchyma, decreased the number of proinflammatory-like microglia/macrophages, increased the number of anti-inflammatory-like microglia/macrophages, and downregulated expression of several proinflammatory factors. Furthermore, ASK1-K716R attenuated white matter injury and improved the nerve conduction function of both myelinated and unmyelinated fibers after TBI. Finally, our findings demonstrated that ASK1-K716R exhibited favorable long-term functional and histological outcomes in the aftermath of TBI.ConclusionASK1-K716R preserves BBB integrity by inhibiting ASK1/JNKs pathway in endothelial cells, consequently reducing the degradation of tight junction proteins. Additionally, it alleviates early neuroinflammation by inhibiting the infiltration of peripheral immune cells into the brain parenchyma and modulating the polarization of microglia/macrophages. These beneficial effects of ASK1-K716R subsequently result in a reduction in white matter injury and promote the long-term recovery of neurological function following TBI.

Autophagy and unfolded protein response induction: a crosstalk between street rabies virus and the host.

The endoplasmic reticulum (ER) response mechanism to cellular stress is mediated by the unfolded protein response/ER-associated degradation (UPR/ERAD) pathway. A viral infection can trigger ER stress and engage some transcription factors, depending on the host cell and virus type, activating or inhibiting autophagy. The relationship between ER response and autophagy in rabies has not been investigated yet. In the present study, the mouse brain was infected with street rabies virus (SRABV). Total RNA was extracted from the brains of animals, and cDNA was synthesized. Next, real-time PCR assay was performed using specific primers. The expression of hypoxanthine-guanine phosphoribosyltransferase (Hprt), CCAAT/enhancer binding protein homologous protein (CHOP), apoptosis signal-regulating kinase 1 (ASK1), activating transcription factor 6 (ATF6), and caspase 3 (CASP3) genes was also investigated. Based on the results, SRABV caused significant changes in the mRNA expression of ATF6, CHOP, and ASK1 genes in the brains of infected mice in the control group (group V). Treatment of infected cells with the pIRES-EGFP-Beclin-1 vector and rapamycin caused changes in nearly most of the parameters. However, alterations in CASP3 gene expression were only observed when the vector and the virus were simultaneously injected into the cells. Overall, protection and autophagy against cell death induced by SRABV infection can be achieved by activating the ER stress pathway, followed by a marked increase in the expression of ATF6, CHOP, ASK1, and CASP3 genes.

Salidroside inhibited cerebral ischemia/reperfusion-induced oxidative stress and apoptosis via Nrf2/Trx1 signaling pathway.

Cerebral ischemia reperfusion injury (CIRI) is still a serious problem threatening human health. Salidroside (SAL) is a natural phenylpropanoid glycoside compound with antioxidant, anti-inflammatory, and anti-ischemic properties. This study investigated the protective mechanism of SAL on middle cerebral artery occlusion (MCAO)- and oxygen-glucose deprivation/reoxygenation (OGD/R) model-induced CIRI via regulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/thioredoxin 1 (Trx1) axis. The results indicated that SAL (50mg/kg or 100mg/kg, intraperitoneal injection) not only effectively alleviated infarction rate, improved histopathological changes, relieved apoptosis by strengthening the suppression of cleaved caspase-3 and Bax/Bcl-2 proteins and decreased malondialdehyde (MDA) formation, but also increased superoxide dismutase (SOD) and catalase (CAT) activities and upregulated the expressions of Nrf2 and Trx1 on MCAO-induced CIRI rats. SAL also efficiently inhibited apoptosis and decreased oxidative stress in OGD/R-stimulated PC12 cells. Furthermore, blocking the Nrf2/Trx1 pathway using tretinoin, an Nrf2 inhibitor, significantly reversed the protective effect of SAL on OGD/R-induced oxidative stress. Moreover, SAL reduced the expression of apoptosis signal-regulating kinase-1 (ASK1) and mitogen-activated protein kinase (MAPK) family proteins. These results demonstrated that SAL inhibited oxidative stress through Nrf2/Trx1 signaling pathway, and subsequently reduced CIRI-induced apoptosis by inhibiting ASK1/MAPK.

Endoplasmic Reticulum Stress Is Involved in Glucocorticoid-Induced Apoptosis in PC12 Cells.

Objective The present study selected PC12 cells to construct a neuronal injury model induced by glucocorticoids (GC) in vitro, aiming to explore whether the endoplasmic reticulum stress (ERS) PKR-like endoplasmic reticulum kinase (PERK)-activating transcription factor 4 (ATF4)-C/EBP-homologous protein (CHOP) and inositol requirement 1 (IRE1)-apoptosis signal regulating kinase 1 (ASK1)-C-Jun amino-terminal kinase (JNK) signaling pathways are associated with the neuronal injury process induced by GC and provide morphological evidence. Methods Cell models with different doses and different durations of GC exposure were established. The viability of PC12 cells was detected by the CCK-8 assay, and the apoptosis rate of PC12 cells was detected by the flow cytometry assay. The expression of microtubule-associated protein 2 (Map2); glucocorticoids receptor (GR); cellular oncogene fos (C-fos); and ERS-related proteins, glucose-regulated protein 78 (GRP78), p-PERK, p-IRE1, ATF4, ASK1, JNK, and CHOP, was observed by immunofluorescence staining. Results The results of immunofluorescence staining showed that PC12 cells abundantly expressed Map2 and GR. The CCK-8 assay revealed that high-concentration GC exposure significantly inhibited the cell viability of PC12 cells. The flow cytometry assay indicated that high-concentration GC exposure significantly increased the apoptosis rate of PC12 cells. Immunofluorescence staining showed that GC exposure significantly increased the expression of C-fos, GRP78, p-PERK, p-IRE1, ATF4, ASK1, JNK, and CHOP. Treatment with ERS inhibitor 4-phenylbutyric acid (4-PBA) and GR inhibitor RU38486 attenuated related damage and downregulated the expression of the abovementioned proteins. Conclusion High-concentration GC exposure can significantly inhibit the viability of PC12 cells and induce apoptosis. PERK-ATF4-CHOP and IRE1-ASK1-JNK pathways are involved in the above damage process.

Levo-corydalmine attenuates microglia activation and neuropathic pain by suppressing ASK1-p38 MAPK/NF-κB signaling pathways in rat spinal cord

Background and objectivesNeuropathic pain is partially refractory to currently available treatments. Although some studies have reported that apoptosis signal-regulating kinase 1 (ASK1) may inhibit chronic pain, the mechanisms underlying this...

Apoptosis signal-regulating kinase 1 inhibition attenuates human airway smooth muscle growth and migration in chronic obstructive pulmonary disease.

Increased airway smooth muscle (ASM) mass is observed in chronic obstructive pulmonary disease (COPD) which is correlated with disease severity and negatively impact lung function in these patients. Thus, there is clear unmet clinical need for finding new therapies which can target airway remodeling and disease progression in COPD. Apoptosis signal-regulating kinase 1 (ASK1) is a ubiquitously expressed mitogen-activated protein kinase kinase kinase (MAP3K) activated by various stress stimuli, including reactive oxygen species (ROS), tumor necrosis factor (TNF)-α, and lipopolysaccharide (LPS) and is known to regulate cell proliferation. ASM cells from COPD patients are hyper-proliferative to mitogens in vitro. However, the role of ASK1 in ASM growth is not established. Here, we aim to determine the effects of ASK1 inhibition on ASM growth and pro-mitogenic signaling using ASM cells from COPD patients. We found greater expression of ASK1 in ASM-bundles of COPD lung when compared with non-COPD. Pre-treatment of ASM cells with highly selective ASK1 inhibitor, TCASK10 resulted in a dose-dependent reduction in mitogen (FBS, PDGF and EGF; 72 hours)-induced ASM growth as measured by CyQuant assay. Further, molecular targeting of ASK1 using siRNA in ASM cells prevented mitogen-induced cell growth. In addition, to anti-mitogenic potential, ASK1 inhibitor also prevented TGFβ1-induced migration of ASM cells in vitro. Immunoblotting revealed that anti-mitogenic effects are mediated by JNK and p38MAP kinase-signaling pathways as evident by reduced phosphorylation of downstream effectors JNK1/2 and p38MAP kinases respectively with no effect on ERK1/2. Collectively, these findings establish the anti-mitogenic effect of ASK1 inhibition and identify a novel pathway that can be targeted to reduce or prevent excessive ASM mass in COPD.

Critical and diverse in vivo roles of apoptosis signal-regulating kinase 1 in animal models of atherosclerosis and cholestatic liver injury.

Apoptosis plays pivotal in vivo roles in not only vital processes, such as cell turnover and embryonic development, but also various inflammatory disorders. However, the role of apoptosis by vascular and hepatic cells in the respective progression of atherosclerosis and liver injury remains controversial. Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase family member that is activated through distinct mechanisms in response to various cytotoxic stressors. ASK1, ubiquitously expressed, is situated in an important upstream position for many signal transduction pathways, which subsequently induce inflammation and/or apoptosis. Our serial in vivo studies have uniquely reported that the expression of phosphorylated ASK1 is variably seen in atherosclerotic lesions or bile-duct-ligation (BDL)-induced injury livers. In mice genetically deficient of ASK1 (ASK1⁻/⁻), activated ASK1 signaling accelerates high-cholesterol-diet-induced necrotic lipid core formation by inducing macrophage apoptosis and enhances ligation injury-induced vascular remodeling via pro-inflammatory reactions and by stimulating apoptosis of smooth muscle cells. In contrast, in models of BDL-induced cholestatic liver injury, the pathogenic roles of ASK1-mediated early necro-inflammation, but not apoptosis, and the proliferation of hepatocytes and cholangiocytes are crucial in subsequent peribiliary fibrosis/fibrogenesis. These animal models of acute to chronic inflammatory diseases show that stimulated ASK1 signaling critically and diversely regulates not only hypercholesterolemia-induced atherosclerosis and injury-induced arteriosclerosis, but also the acute and subacute-to-chronic phase of BDL-induced cholestasis. We herein review the diverse, key in vivo roles of ASK1 signaling in the pathogenesis of inflammatory disorders closely related to metabolic syndrome.

Apoptosis signal-regulating kinase 1 exhibits oncogenic activity in pancreatic cancer.

Pancreatic cancer has an extremely grim prognosis, with an overall 5-year survival rate less than 5%, as a result of its rapid metastasis and late diagnosis. To combat this disease, it is crucial to better understand the molecular mechanisms that contribute to its pathogenesis. Herein, we report that apoptosis signal-regulating kinase 1 (ASK1) is overexpressed in pancreatic cancer tissues and that its expression correlates with the histological grade of pancreatic cancer. The expression of ASK1 is also elevated in pancreatic cancer cell lines at both protein and mRNA levels. In addition, ASK1 promotes the proliferation and stimulates the tumorigenic capacity of pancreatic cancer cells. These functions of ASK1 are abrogated by pharmacological inhibition of its kinase activity or by introduction of a kinase-dead mutation, suggesting that the kinase activity of ASK1 is required for its role in pancreatic cancer. However, the alteration of ASK1 expression or activity does not significantly affect the migration or invasion of pancreatic cancer cells. Collectively, these findings reveal a critical role for ASK1 in the development of pancreatic cancer and have important implications for the diagnosis and treatment of this malignancy.

NQDI-1, an inhibitor of ASK1 attenuates acute perinatal hypoxic-ischemic cerebral injury by modulating cell death.

Apoptosis signal-regulating kinase 1 (ASK1) is a ubiquitously expressed protein kinase, which regulates cell fate in numerous injury conditions. Therefore, ASK1 may be a promising novel therapeutic target for injury. However, the expression and distribution of ASK1 in the perinatal brain following hypoxia-ischemia (HI) remains to be elucidated. In the present study, western blotting and immunofluorescence were used to determine the expression and distribution of ASK1 and any associated downstream targets in the perinatal rat brain following HI. NQDI-1, a specific inhibitor of ASK1 was intracerebroventricularly injected following neonatal rats brain insult for neuroprotection. The results revealed an increased expression of ASK1 and this expression was localized to the neurons and astrocytes, compared with the sham controls. Additionally, it was demonstrated that the ASK1/c-Jun N-terminal kinases (JNK) pathway was involved in the brain damage following HI in neonatal rats. Notably, NQDI-1 significantly inhibited the in vivo expression levels of ASK1, phosphorylated (p-)JNK, p-c-Jun, p53 and caspase 3. Reduced acute hypoxic-ischemic cerebral injury and cell apoptosis was observed following the injection of NQDI-1. Collectively, NQDI-1 attenuated acute perinatal hypoxic-ischemic cerebral injury by inhibiting the expression of ASK1 and cell apoptosis. This may be a promising novel neuroprotective inhibitor for perinatal cerebra injury.

Solanine-induced reactive oxygen species inhibit the growth of human hepatocellular carcinoma HepG2 cells.

The aim of the present study was to investigate the effect of solanine on promoting human hepatocellular carcinoma HepG2 cells to produce reactive oxygen species (ROS), and the molecular mechanisms leading to tumor cell apoptosis. Solanine was administered to HepG2 cells in vitro. A selection of probes targeting various cellular localizations of ROS were used to detect ROS expression using flow cytometry. The expression levels of apoptosis-associated proteins, including apoptosis signal-regulating kinase 1 (ASK1) and thioredoxin binding protein 2 (TBP-2), and proliferation-associated proteins, including histone deacetylase 1 (HDAC1), were detected using western blotting. The percentage of cells undergoing apoptosis was measured using an Annexin V-fluorescein isothiocyanate/propidium iodide assay, and cell morphology was examined using Wright's stain followed by inverted microscopy analysis. ROS detection probes 2',7'-dichlorofluorescin diacetate and dihydrorhodamine 123 identified that abundant ROS, including hydroxyl radical (OH-) and hydrogen peroxide (H2O2), were produced in the cytoplasm and mitochondria of the solanine-treated HepG2 cells compared with the control cells (P<0.05). Superoxide anion specific probes dihydroethidium and MitoSOX™ demonstrated that there were no significant alterations in the HepG2 cells following solanine treatment compared with the control cells (P>0.05). Western blotting results revealed that solanine upregulated the expression levels of ASK1 and TBP-2 and enhanced their kinase activities, whereas solanine decreased the expression level of the proliferation-associated protein, HDAC1. The cell apoptotic rate was significantly increased (P<0.0001) in the solanine-treated HepG2 cells compared with the control cells. (P<0.05). Overall, the study indicated that solanine induces HepG2 cells to produce ROS, mainly OH- and H2O2, in a mitochondria-dependent and -independent manner. In addition, solanine stimulates the expression of ASK1 and TBP-2, and their kinase activities, but inhibits the expression of proliferation-associated proteins, such as HDAC1, thus contributing to HepG2 cell apoptosis.

Differential caspase activity in the cortex and striatum with chronic infusion of 3-nitropropionic acid

Systemic administration of 3-nitropropionic acid (3-NP) facilitates the development of select striatal lesions, and some reports provide clues about this pathology. In this study, we investigated the relationship between reduced levels of brain-derived neurotrophic factor (BDNF) in lesioned brain regions and caspase activity, as well as involvement of apoptosis signal-regulating kinase 1 (ASK1) in caspase activation. We analyzed apoptotic cell death, BDNF distribution, caspase-3 activity, caspase-6 activity, ASK1 expression level, and active ASK1 in the cortex and striatum. There were different levels and distributions of these factors within each sub-region. Caspase-6 activity was reduced with down-regulation of ASK1 in the cortex. BDNF protein levels did not decrease in the cortex, but there was replenishment of severely reduced BDNF in the striatum. The present study suggests that an increase in ASK1 in the damaged cortex is related to caspase-6 activation and is involved in cortical depletion of BDNF in the striatum. Furthermore, with systemic infusion of 3-NP, differential expression of ASK1 in the cortex and striatum suggests that this kinase may modulate caspase activation and striatal degeneration.

The effect of ASK1 on vascular permeability and edema formation in cerebral ischemia

Apoptosis signal-regulating kinase-1 (ASK1) is the mitogen-activated protein kinase kinase kinase (MAPKKK) and participates in the various central nervous system (CNS) signaling pathways. In cerebral ischemia, vascular permeability in the brain is an important issue because regulation failure of it results in edema formation and blood–brain barrier (BBB) disruption. To determine the role of ASK1 on vascular permeability and edema formation following cerebral ischemia, we first investigated ASK1-related gene expression using microarray analyses of ischemic brain tissue. We then measured protein levels of ASK1 and vascular endothelial growth factor (VEGF) in brain endothelial cells after hypoxia injury. We also examined protein expression of ASK1 and VEGF, edema formation, and morphological alteration through cresyl violet staining in ischemic brain tissue using ASK1-small interference RNA (ASK1-siRNA). Finally, immunohistochemistry was performed to examine VEGF and aquaporin-1 (AQP-1) expression in ischemic brain injury. Based on our findings, we propose that ASK1 is a regulating factor of vascular permeability and edema formation in cerebral ischemia.

Targeting apoptosis signalling kinase-1 (ASK-1) does not prevent the development of neuropathy in streptozotocin-induced diabetic mice.

Apoptosis signal-regulating kinase-1 (ASK1) is a mitogen-activated protein 3 kinase (MAPKKK/MAP3K) which lies upstream of the stress-activated MAPKs, JNK and p38. ASK1 may be activated by a variety of extracellular and intracellular stimuli. MAP kinase activation in the sensory nervous system as a result of diabetes has been shown in numerous preclinical and clinical studies. As a common upstream activator of both p38 and JNK, we hypothesised that activation of ASK1 contributes to nerve dysfunction in diabetic neuropathy. We therefore wanted to characterize the expression of ASK1 in sensory neurons, and determine whether the absence of functional ASK1 would protect against the development of neuropathy in a mouse model of experimental diabetes. ASK1 mRNA and protein is constitutively expressed by multiple populations of sensory neurons of the adult mouse lumbar DRG. Diabetes was induced in male C57BL/6 and transgenic ASK1 kinase-inactive (ASK1n) mice using streptozotocin. Levels of ASK1 do not change in the DRG, spinal cord, or sciatic nerve following induction of diabetes. However, levels of ASK2 mRNA increase in the spinal cord at 4 weeks of diabetes, which could represent a future target for this field. Neither motor nerve conduction velocity deficits, nor thermal or mechanical hypoalgesia were prevented or ameliorated in diabetic ASK1n mice. These results suggest that activation of ASK1 is not responsible for the nerve deficits observed in this mouse model of diabetic neuropathy.

Abstract 2280: Role of apoptosis signal-regulating kinase 1 in the cell apoptosis in oral leukoplakia

Abstract Oral leukoplakia is a common precancerous lesion. The mechanism is not clear. The aim is to investigate the roles of apoptosis signal-regulating kinase 1(ASK1) in the cell apoptosis in oral leukoplakia. Archival tissue sections of 10 oral leukoplakia,23 oral leukoplakia with mild to moderate dysplasia, 7 normal oral mucosa were detected by real time PCR and immunohistochemical staining of markers of ASK1 and p-ASK1.The cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated nucleotide shift enzyme(TdT) mediated d-UTP end labeling(TUNEL). The results showed The mRNA and protein expression of ASK1 in oral leukoplakia with mild to moderate dysplasia was higher than the normal mucosa(p&amp;lt;0.05).From oral normal mucosa to oral leukoplakia to mild to moderate dysplasia, the expression of p-ASK1 was increased with the increasing grade( p&amp;lt;0.05).The apoptosis in oral leukoplakia and mild to moderate dysplasia increased more than normal mucose(p&amp;lt;0.05). It suggests that ASK1 and p-ASK1 are positive correlation with the increased apoptosis in the development of oral leukoplakia, its related signal pathways and cascade may play an important role in the cell apoptosis in oral leukoplakia. Citation Format: Xiaofei Tang, Jian-Fei Zhang, Wen-wen Niu, Min Zhang. Role of apoptosis signal-regulating kinase 1 in the cell apoptosis in oral leukoplakia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2280. doi:10.1158/1538-7445.AM2014-2280

Heat-shock protein 70 modulates apoptosis signal-regulating kinase 1 in stressed hepatocytes of Mugil cephalus.

Oxidative stress causes damage at the cellular level and activates a number of signaling pathways. Heat-shock proteins (HSPs) play an important role in repair and protective mechanisms under cell response to stress conditions. HSP70 has been shown to act as an inhibitor of apoptosis. Apoptosis signal-regulating kinase-1 (ASK1) activity is regulated at multiple levels, one of which is through inhibition by cytosolic chaperons HSP70. The current study was aimed to investigate the alteration in signaling molecules that allow the fish to survive under stressed natural field conditions. The study also investigates the variation in biomolecular composition of hepatocytes by using Fourier transform infrared spectroscopy. The impact of stress on hepatocytes was assessed by measuring the level of lipid peroxides (LPO), catalase activity (CAT) and assessing the changes in hepatocytes of Mugil cephalus inhabiting Kovalam and Ennore estuaries. The expression of HSP70 and ASK1 were analyzed by immunoblot analysis and ELISA, respectively. The spectral analysis showed variations in biomolecular composition of hepatocytes at a wave number region of 4,000-400 cm(-1). There was significant decrease of CAT activity (p < 0.01) (25 %) with significant increase of LPO (p < 0.001) (35 %) and HSP70 (p < 0.001) and insignificant increase of ASK1 (p < 0.05) (16 %) in fish hepatocytes inhabiting Ennore estuary than Kovalam estuary. In conclusion, the present study suggests that the survival of fish in the Ennore estuary under stressed condition may be due to the upregulation of HSP70 that mediates the altered signal pathway which promotes cellular resistance against apoptosis.

Apoptosis signal-regulating kinase 1 is associated with the effect of claudin-6 in breast cancer

BackgroundPrevious studies have demonstrated that claudin-6 functions as a cancer suppressor in human MCF-7 breast cancer cells. The growth inhibitory effect could be attributed to inhibition of cell proliferation and induction of apoptosis. The purpose of the current study was to examine the involvement of apoptosis signal-regulating kinase 1 (ASK1) in the anticancer effect of claudin-6.MethodsImmunohistochemical analysis was performed to evaluate the ASK1 protein expression and the correlation between ASK1, claudin-6 and clinicopathological features in 85 samples of breast invasive ductal carcinomas (IDC). Western blotting and RT-PCR was carried out to examine the expression of ASK1 and claudin-6 in MCF-7 cell clones transfected with claudin-6.ResultsImmunohistochemical analysis showed that ASK1 expression was significantly related with that of claudin-6 in breast invasive ductal carcinomas (P < 0.05). In addition, a positive correlation between ASK1 and C-erb B 2 protein expression was identified (P < 0.05). Western blotting and RT-PCR consistently revealed that the level of ASK1 protein and mRNA was upregulated in MCF-7 cell clones transfected with claudin-6.ConclusionsOur data suggests, for the first time, that the ASK1 signal may play a positive role in the inhibitory effect of claudin-6 in breast cancer.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1200314318763661

Abstract 3133: Apoptosis signal-regulating kinase 1 and cyclin D1 compose a positive feedback loop contributing to tumor growth in gastric cancer

Abstract Gastric cancer is a common cancer worldwide, associated with a high mortality despite its declining incidence in recent decades. Although the role of H. pylori in causing mucosal effects has been investigated, which molecular signal(s) initiate the program of irreversible transformation remain unclear, and thus molecular targeting therapies for GC have not been well established. Mitogen-activated protein kinase (MAPK) pathways regulate multiple cellular functions and have been demonstrated to be highly active in many types of human cancers, and we have previously reported that c-Jun-N-terminal kinase 1 (JNK1) is important for gastric tumorigenesis. Apoptosis signal-regulating kinase 1 (ASK1) is an upstream MAPK known to be involved in apoptosis, inflammation, and carcinogenesis. In the current study, we investigated the role of ASK1 in the development of gastric cancer. In human gastric cancer specimens, we observed increased ASK1 expression compared to non-tumor epithelium, while we found no difference between colon cancer and non-tumor colon epithelium. Using the chemically induced murine gastric tumorigenesis model, we observed increased tumor ASK1 expression, and ASK1 knockout mice displayed both a lower number and smaller tumor size compared to wild-type mice. In gastric cancer cell lines, immunoprecipitation analysis revealed constitutive ASK1 activation in several cell lines. ASK1 siRNA inhibited cell proliferation through the accumulation of cells in G1 phase of the cell cycle, and reduced cyclin D1 expression in gastric cancer cells, while these effects were uncommon in other cancer cells, suggesting that the ASK1-dependent regulation of the cyclin D1 level and cellular proliferation is specific to gastric cancer. Overexpression of ASK1 induced the transcription of cyclin D1 through AP-1 activation in a kinase-dependent manner. In addition, we found that the expression of ASK1 was elevated following epidermal growth factor (EGF) or Helicobacter pylori (H.pylori) treatment in control cells but not in cyclin D1 silencing cells. Overexpression of cyclin D1 enhanced phosphorylation of Rb, followed by the increase in ASK1 expression. Chromatin immunoprecipitation (ChIP) assay showed that cyclin D1 expression increase E2F1 binding to ASK1 promoter, suggesting that the levels of ASK1 were regulated by cyclin D1 through the Rb-E2F pathway. Exogenous ASK1 induced cyclin D1 expression, followed by an elevated expression of endogenous ASK1. These results indicate an autoregulatory mechanism of ASK1 in the development of gastric cancer. Through targeting this positive feedback loop, ASK1 may present a potential therapeutic target for the treatment of advanced gastric cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3133. doi:10.1158/1538-7445.AM2011-3133

Apoptosis Signal-Regulating Kinase1 is Inducible by Protein Kinase Cδ and Contributes to Phorbol Ester-Mediated G1 Phase Arrest Through Persistent JNK Activation

Although protein kinase Cδ (PKCδ) has been suggested in the negative control of the cell cycle machinery in many types of cancer cells, its underlying mechanisms are partly understood. Here we report that the expression of apoptosis signal-regulating kinase1 (ASK1) is inducible in a PKCδ-dependent manner, and contributes to phorbol ester-induced cell cycle arrest through persistent JNK activation in breast cancer epithelial cells. Activation of PKC with phorbol 12-myristate 13-acetate (PMA) gradually up-regulated the expression of ASK1 mRNA and protein, and subsequently enhanced its catalytic activity in MCF-7 cells. Importantly, such PMA-induced ASK1 expression was completely abolished by pretreatment of rottlerin, a specific PKCδ inhibitor or by knocking down the expression of PKCδ, while ectopic expression of a constitutively active form of PKCδ strongly up-regulated ASK1 expression. We also found that the persistent activation of mitogen-activated protein kinase, JNK in response to PMA was greatly attenuated by RNA interference-mediated knockdown of ASK1. Taken together, these results suggest that inducible expression of ASK1 by PKCδ contributes to the G1 arrest by enhancing persistent JNK signaling activation which represents a novel alternative mechanism of PKCδ-dependent cell cycle arrest and limiting proliferation of breast cancer epithelial cells.

Apoptosis signal-regulating kinase 1 and cyclin D1 compose a positive feedback loop contributing to tumor growth in gastric cancer

Mitogen-activated protein kinase (MAPK) pathways regulate multiple cellular functions and are highly active in many types of human cancers. Apoptosis signal-regulating kinase 1 (ASK1) is an upstream MAPK involved in apoptosis, inflammation, and carcinogenesis. This study investigated the role of ASK1 in the development of gastric cancer. In human gastric cancer specimens, we observed increased ASK1 expression, compared to nontumor epithelium. Using a chemically induced murine gastric tumorigenesis model, we observed increased tumor ASK1 expression, and ASK1 knockout mice had both fewer and smaller tumors than wild-type (WT) mice. ASK1 siRNA inhibited cell proliferation through the accumulation of cells in G1 phase of the cell cycle, and reduced cyclin D1 expression in gastric cancer cells, whereas these effects were uncommon in other cancer cells. ASK1 overexpression induced the transcription of cyclin D1, through AP-1 activation, and ASK1 levels were regulated by cyclin D1, via the Rb-E2F pathway. Exogenous ASK1 induced cyclin D1 expression, followed by elevated expression of endogenous ASK1. These results indicate an autoregulatory mechanism of ASK1 in the development of gastric cancer. Targeting this positive feedback loop, ASK1 may present a potential therapeutic target for the treatment of advanced gastric cancer.