Role of apoptosis signal-regulating kinase 1 in left ventricular remodeling in mice / 中国当代儿科杂志

OBJECTIVE@#To study the changes and significance of apoptosis signal-regulating kinase 1 (ASK1) in left ventricular remodeling in FVB/N mice.@*METHODS@#A total of 54 FVB/N mice were randomly divided into 4 groups: 0 d group with 8 mice, 7 d group with 10 mice, 14 d group with 16 mice, and 21 d group with 20 mice. A model of cardiac remodeling was established by intraperitoneal injection of isoproterenol (ISO) at a daily dose of 30 mg/kg, and the 7 d, 14 d, and 21 d groups were injected for 7, 14, and 21 consecutive days respectively. The 0 d group was given intraperitoneal injection of an equal volume of normal saline. Echocardiography was used to measure left ventricular posterior wall thickness at end diastole (dLVPW) and the ratio of heart weight to tibia length (HW/TL) was measured. Hematoxylin-eosin staining was used to measure left ventricular myocardial fiber diameter. Picric-Sirius red staining was used to measure myocardial collagen deposition area in the left ventricle. Quantitative real-time PCR was used to measure the mRNA expression of ASK1, type I collagen (collagen I), and B-type natriuretic peptide (BNP). The mortality rate was observed for each group.@*RESULTS@#There were gradual increases in HW/TL, myocardial fiber diameter, and dLVPW after 0, 7, and 14 days of ISO injection (P0.05), while there was a significant reduction in myocardial fiber diameter (P0.05). There were significant increases in myocardial collagen deposition area and the mRNA expression of collagen I, ASK1, and BNP after 0, 7, 14, and 21 days of ISO injection, which reached the peaks on day 21 (P<0.01). The mRNA expression of ASK1 was positively correlated with myocardial collagen deposition area and the mRNA expression of collagen I and BNP and had a weak correlation with HW/TL, myocardial fiber diameter, and dLVPW. There was a significant increase in the mortality rate of the mice over the time of ISO injection.@*CONCLUSIONS@#The expression of ASK1 in the myocardium is closely associated with left ventricular remodeling. The increase of ASK1 expression may lead to the aggravation of left ventricular remodeling, and the mechanism of which needs further study.

Involvement of miR-Let7A in inflammatory response and cell survival/apoptosis regulated by resveratrol in THP-1 macrophage

BACKGROUND/OBJECTIVES: Resveratrol, a natural polyphenol, has multiple functions in cellular responses including apoptosis, survival, and differentiation. It also participates in the regulation of inflammatory response and oxidative stress. MicroRNA-Let-7A (miR-Let7A), known as a tumor suppressor miRNA, was recently reported to play a crucial role in both inflammation and apoptosis. Therefore, we examined involvement of miR-Let7A in the modulation of inflammation and cell survival/apoptosis regulated by resveratrol. MATERIALS/METHODS: mRNA expression of pro-/anti-inflammatory cytokines and sirtuin 1 (SIRT1), and protein expression of apoptosis signal-regulating kinase 1 (ASK1), p-ASK1, and caspase-3 and cleaved caspase-3 were measured, and cell viability and Hoechst/PI staining for apoptosis were observed in Lipopolysaccharide (LPS)-stimulated human THP-1 macrophages with the treatment of resveratrol and/or miR-Let7A overexpression. RESULTS: Pre-treatment with resveratrol (25-200 µM) resulted in significant recovery of the reduced cell viabilities under LPS-induced inflammatory condition and in markedly increased expression of miR-Let7A in non-stimulated or LPS-stimulated cells. Increased mRNA levels of tumor necrosis factor-α and interleukin (IL)-6 induced by LPS were significantly attenuated, and decreased levels of IL-10 and brain-derived neurotrophic factor were significantly restored by resveratrol and miR-Let7A overexpression, respectively, or in combination. Decreased expression of IL-4 mRNA by LPS stimulation was also significantly increased by miR-Let7A overexpression co-treated with resveratrol. In addition, decreased SIRT1 mRNA levels, and increased p-ASK1 levels and PI-positive cells by LPS stimulation were significantly restored by resveratrol and miR-Let7A overexpression, respectively, or in combination. CONCLUSIONS: miR-Let7A may be involved in the inflammatory response and cell survival/apoptosis modulated by resveratrol in human THP-1 macrophages.

Sodium tanshinone II A sulfonate ameliorates microcirculatory disturbance of small intestine by attenuating the production of reactie oxygen species in rats with sepsis / 中国结合医学杂志

<p><b>OBJECTIVE</b>To examine whether sodium tanshinone II A sulfonate (STS), the main effective component of Salvia miltiorrhiza is effective in relieving the microcirculatory disturbance of small intestine by suppressing the production of reactive oxygen species (ROS) in rats with sepsis.</p><p><b>METHODS</b>A rat model of sepsis was induced by cecal ligation and puncture (CLP). Rats (n =40) were randomly divided into 4 groups: sham-operated group (sham, n =10), sepsis group (CLP, n =10), STS treatment group (STS, n =10) and ROS scavenger dimethylthiourea (DMTU, n =10) group. Animals in the STS group were injected with STS (1 mg/kg) for 10 min through the right external jugular vein after the CLP operation, and animals in the CLP group were given the same volume of normal saline after the CLP operation. Animals in the DMTU group were intraperitoneally injected with 5 mL/kg of 20% DMTU 1 h before CLP. The histopathologic changes in the intestinal tissues and changes of mesenteric microcirculation were observed. The levels of ROS in intestinal tissues from each group were qualitatively evaluated using a fluorescent microscope. The expressions of apoptosis signal-regulating kinase (ASK1), phosphorylated ASK1 (phospho-ASK1), p38 mitogen-activated protein kinases (p38 MAPK), phosphorylated p38 MAPK (phospho-p38 MAPK) and tissue factor (TF) were determined by Western blotting.</p><p><b>RESULTS</b>It was shown that there were obvious microcirculatory disturbance (P <0.05) and tissue injuries in intestinal tissues after CLP operation. The levels of ROS production, phospho-ASK1, phospho-p38 MAPK and TF were increased. Both STS and DMTU suppressed ROS, phospho-ASK1, phospho-p38 MAPK and TF production, and ameliorated the microcirculatory disturbance and tissues injury (P <0.01).</p><p><b>CONCLUSION</b>STS can ameliorate the microcirculatory disturbance of the small intestine by attenuating the production of ROS in rats with sepsis.</p>

Role of PRKCD and ASK1 in U937 cell differentiation / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the expression of ASK1 and PRKCD in the process of monocyte differentiation, and explore their role in functional changes of hypersplenism spleen macrophages (Mφ) in portal hypertension (PH).</p><p><b>METHODS</b>U937 cells were stimulated to differentiate into monocyte/macrophage-like cells by cultivation in PMA and the mRNA expressions of ASK1 and PRKCD were detected by q-PCR and the changes of protein expression were identified by western blot analysis. The secretion of phagocytose related cytokines such as IL-10 and TNF-α were tested by ELISA, and the function of the macrophage-like cells were studied by chicken red blood cell phagocytose test.</p><p><b>RESULTS</b>The expressions of PRKCD and ASK1 mRNA were gradually decreased along with the cell differentiation, while the secretion of TNF-α was increased, IL-10 secretion reached a maximum at 24 h after PAM stimulation, and then gradually fell. The expression of ASK1 and p-ASK1 were rapidly increased compared with the non-stimulated U937 cells, while the expression of PRKCD and p-PRKCD were sightly declined. The phagocytose test show that U937 cells induced with PMA were able to swallow the chicken red blood cell.</p><p><b>CONCLUSION</b>Up-regulated protein expression of ASK1 and p-ASK1 and down-regulated protein expression of PRKCD and p-PRKCD in the process of PMA induced monocyte differentiation, are consist with the expression changes of splenic macrophage phagocytosis in hypersplenism, which leads to increased activity of Mφ.</p>

Effect of suppressing apoptosis signal regulating kinase 1 on GFAP and vimentin expression and hindlimb mobility in rats after spinal cord injury / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of suppressing apoptosis signal regulating kinase 1 (ASK1) on glial fibrillary acidic protein (GFAP) and vimentin expressions at the injury site and on hindlimb mobility in rats after spinal cord injury (SCI).</p><p><b>METHODS</b>The rat models of SCI were established by extradural compression of the spinal cord using an aneurysm clip. The injured rats were treated with normal saline (model group), ASK1 specific inhibitor thioredoxin (Trx group), or ASK1 monoclonal antibody (Anti-ASK1 group), and the rats receiving a sham operation underwent laminectomy without SCI. The expression of GFAP and vimentin were detected by Western blotting and immunofluorescence assay at 1, 7, 14 and 28 days after SCI. The motion function of the hindlimbs of the injured rats was assessed with Basso Beattie Bresnahan (BBB) scores, and somatosensory-evoked potentials (SEP) and motor-evoked potentials (MEP) were determined to examine the electrophysiological changes.</p><p><b>RESULTS</b>At 1 day after SCI, the expressions of GFAP and vimentin showed no significant differences among the groups; at 7, 14 and 28 days after SCI, GFAP and vimentin expressions significantly increased in Trx and Anti-ASK1 groups compared with those in the model group (P<0.01). The BBB scores showed no significant differences among the groups at 1, 7 and 14 days after SCI, while at 28 days, the BBB scores in Trx and Anti-ASK1 groups were significantly higher than those in the model group (P<0.01). At 28 days after SCI, the latent period of SEP and MEP decreased and the amplitude increased significantly in Trx and Anti-ASK1 groups compared with that in the model group (P<0.01).</p><p><b>CONCLUSION</b>Blocking ASK1 can inhibit the expression of GFAP and vimentin in glial scars and improve the outcomes of hindlimb mobility in rats after SCI.</p>

Apoptosis signal-regulating kinase 1 (ASK1) is linked to neural stem cell differentiation after ischemic brain injury

Neural stem cells (NSCs) have been suggested as a groundbreaking solution for stroke patients because they have the potential for self-renewal and differentiation into neurons. The differentiation of NSCs into neurons is integral for increasing the therapeutic efficiency of NSCs during inflammation. Apoptosis signal-regulating kinase 1 (ASK1) is preferentially activated by oxidative stress and inflammation, which is the fundamental pathology of brain damage in stroke. ASK1 may be involved in the early inflammation response after stroke and may be related to the differentiation of NSCs because of the relationship between ASK1 and the p38 mitogen-activated protein kinase pathway. Therefore, we investigated whether ASK1 is linked to the differentiation of NSCs under the context of inflammation. On the basis of the results of a microarray analysis, we performed the following experiments: western blot analysis to confirm ASK1, DCX, MAP2, phospho-p38 expression; fluorescence-activated cell sorting assay to estimate cell death; and immunocytochemistry to visualize and confirm the differentiation of cells in brain tissue. Neurosphere size and cell survival were highly maintained in ASK1-suppressed, lipopolysaccharide (LPS)-treated brains compared with only LPS-treated brains. The number of positive cells for MAP2, a neuronal marker, was lower in the ASK1-suppressed group than in the control group. According to our microarray data, phospho-p38 expression was inversely linked to ASK1 suppression, and our immunohistochemistry data showed that slight upregulation of ASK1 by LPS promoted the differentiation of endogenous, neuronal stem cells into neurons, but highly increased ASK1 levels after cerebral ischemic damage led to high levels of cell death. We conclude that ASK1 is regulated in response to the early inflammation phase and regulates the differentiation of NSCs after inflammatory-inducing events, such as ischemic stroke.

ASK1 is Involved in EBV LMP1-induced NF-kappaB Activation

Epstein-Barr virus (EBV) latent infection transforms B lymphocytes into proliferating lymphoblastoid cell lines (LCLs). EBV latent infection membrane protein 1 (LMP1) is required for EBV-mediated B lymphocyte transformation, and LMP1-induced NF-kappaB activation is essential for LCL survival. Previously, it was reported that the level of reactive oxygen species (ROS) and the expression of apoptosis signal-regulating kinase 1 (ASK1) are elevated in EBV-positive Burkitt's lymphoma (BL) cells, the potential role of ASK1 in LMP1-induced NF-kappaB activation was thus investigated in this study. In EBV-positive BL cells, ASK1 was highly expressed and activated. In addition, TRAF6-ASK1 interaction was significantly increased in EBV-positive BL cells. Interestingly, the expression of LMP1 alone facilitated ASK1 activation. The expression of a dominant negative ASK1 mutant (ASK1KM) strongly blocked LMP1-induced NF-kappaB activation. Furthermore, LMP1-induced NF-kappaB activation was significantly reduced in ASK1 knock out (ASK1-/-) mouse embryonic fibroblasts (MEFs). Taken together, these results demonstrate that ASK1 is activated by LMP1 and is critical for LMP1-induced NF-kappaB activation.

Relationship between MAP3K5 and Epstein-Barr virus-encoded miR-BART22 expression in nasopharyngeal carcinoma / 南方医科大学学报

<p><b>OBJECTIVE</b>To detect the expression of MAP3K5 and miR-BART22 encoded by Epstein-Barr virus and explore their relationship in nasopharyngeal carcinomas (NPCs).</p><p><b>METHODS</b>Fifty-three archived specimens of NPCs and 30 nasopharyngitis specimens were collected for detecting the expression of EBERs and miR-BART22 by in situ hybridization, and the expression of MAP3K5 was detected using immunohistochemistry. Ten fresh NPC and 10 fresh nasopharyngitis specimens were also obtained for determining the protein expression of MAP3K5 by Western blotting.</p><p><b>RESULTS</b>EBERs were positive in all the 53 NPC specimens, and miR-BART22 was positive in 49 specimens; all the 30 nasopharyngitis specimens were negative for EBER or miR-BART22. In the 53 NPC tissues, 50 were negative for MAP3K5 expression in the cancer areas but positive in the adjacent mucosal areas, with the other 3 specimens showing a weak positivity (+). In the 30 nasopharyngitis specimens, 25 showed strong MAP3K5 positivity, 3 showed weak positivity and 2 were negative for MAP3K5 (P<0.001). Western blotting showed that the expression of MAP3K5 protein was significantly higher in nasopharyngitis than in NPC tissues (P=0.029). The expression of MAP3K5 and miR-BART22 was inversely correlated (P<0.001).</p><p><b>CONCLUSION</b>Compared with the adjacent mucosal tissues, NPC tissues have a lower expression of MAP3K5 but a higher expression of miR-BART22. The expression of MAP3K5 and miR-BART22 is inversely correlated, suggesting the possibility of MAP3K5 to serve as target gene of EBV miR-BART22. miR-BART22 may inhibit the expression of MAP3K5, thus reducing the protein phosphorylation of MAPK pathway downstream genes, inhibiting NPC cell apoptosis, preventing their differentiation and promoting their escape from immune surveillance.</p>

Dyrk1A Positively Stimulates ASK1-JNK Signaling Pathway during Apoptotic Cell Death

Dual-specificity tyrosine (Y)-phosphorylation-regulated protein kinase 1A (Dyrk1A) is the mammalian homologue of Drosophila melanogaster minibrain and its human gene is mapped to the Down syndrome critical region of chromosome 21. Dyrk1A phosphorylates several transcription factors, including NFAT and CREB and a number of cytosolic proteins such as APP, tau, and alpha-synuclein. Although Dyrk1A is involved in the control of cell growth and postembryonic neurogenesis, its potential role during cell death and signaling pathway is not clearly understood. In the present study, we show that Dyrk1A is activated under the condition of apoptotic cell death. In addition, Dyrk1A is coupled to JNK1 activation, and directly interacts with apoptosis signal-regulating kinase 1 (ASK1). Moreover, Dyrk1A positively regulates ASK1-mediated JNK1-signaling, and appears to directly phosphorylate ASK1. These data indicate that Dyrk1A regulates cell death through facilitating ASK1-mediated signaling events.

Effects of berberine on the pancreatic beta cell apoptosis in rats with insulin resistance / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the effects of berberine on the pancreatic 13 cell apoptosis in rats with insulin resistance (IR).</p><p><b>METHODS</b>IR Wistar rat model was established by feeding with high fructose diet. After 6-week treatment of berberine, oral glucose tolerance test (OGTT) was performed. Then fasting insulin level (Fins) was detected and insulin sensitivity index (ISI) calculated. The islet was isolated and purified. The pancreatic p3 cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL). The apoptosis-related protein ASK1 and Caspase-12 expressions were examined by immunohistochemical assay.</p><p><b>RESULTS</b>Compared with the normal group, the blood glucose at 0 and 1 h increased, the Fins increased and ISI decreased, the blood lipids were disarranged, the pancreatic beta cell apoptosis increased, and ASK1 and Caspase-12 protein expressions increased in IR rats. Compared with the model group, the blood glucose at 0 and 1 h and the Fins decreased, ISI increased, the disarranged blood lipids were improved, the pancreatic beta cell apoptosis decreased, and the ASK1 expression decreased, but with no obvious change in the Caspase-12 expressions in the berberine group.</p><p><b>CONCLUSIONS</b>Berberine could alleviate IR state in IR rats and inhibit pancreatic 13 cell apoptosis. Its mechanism might be correlated with the inhibition of ASK1 protein expressions.</p>

Molecular Mechanism of Reactive Oxygen Species-dependent ASK1 Activation in Innate Immunity

Apoptosis signal-regulating kinase 1 (ASK1), a mitogen- activated protein kinase kinase kinase, plays pivotal roles in stress responses. In addition, ASK1 has emerged as a key regulator of immune responses elicited by pathogen-associated molecular patterns (PAMPs) and endogenous danger signals. Recent studies have demonstrated that reactive oxygen species (ROS)-dependent activation of ASK1 is required for LPS-stimulated cytokine production as well as extracellular ATP-induced apoptosis in immune cells. The mechanism of ROS-dependent regulation of ASK1 activity by thioredoxin and TRAFs has been well characterized. In this review, we focus on the molecular details of the activation of ASK1 and its involvement in innate immunity.

Molecular Mechanism of Reactive Oxygen Species-dependent ASK1 Activation in Innate Immunity

Apoptosis signal-regulating kinase 1 (ASK1), a mitogen- activated protein kinase kinase kinase, plays pivotal roles in stress responses. In addition, ASK1 has emerged as a key regulator of immune responses elicited by pathogen-associated molecular patterns (PAMPs) and endogenous danger signals. Recent studies have demonstrated that reactive oxygen species (ROS)-dependent activation of ASK1 is required for LPS-stimulated cytokine production as well as extracellular ATP-induced apoptosis in immune cells. The mechanism of ROS-dependent regulation of ASK1 activity by thioredoxin and TRAFs has been well characterized. In this review, we focus on the molecular details of the activation of ASK1 and its involvement in innate immunity.