Social Transmission and Buffering of Hippocampal Metaplasticity after Stress in Mice.

In social animals, the behavioral and hormonal responses to stress can be transmitted from one individual to another through a social transmission process, and, conversely, social support ameliorates stress responses, a phenomenon referred to as social buffering. Metaplasticity represents activity-dependent synaptic changes that modulate the ability to elicit subsequent synaptic plasticity. Authentic stress can induce hippocampal metaplasticity, but whether transmitted stress has the same ability remains unknown. Here, using an acute restraint-tailshock stress paradigm, we report that both authentic and transmitted stress in adult male mice trigger metaplastic facilitation of long-term depression (LTD) induction at hippocampal CA1 synapses. Using LTD as a readout of persistent synaptic consequences of stress, our findings demonstrate that, in a male-male dyad, stress transmission happens in nearly half of naive partners and stress buffering occurs in approximately half of male stressed mice that closely interact with naive partners. By using a social-confrontation tube test to assess the dominant-subordinate relationship in a male-male dyad, we found that stressed subordinate mice are not buffered by naive dominant partners and that stress transmission is exhibited in ∼60% of dominant naive partners. Furthermore, the appearance of stress transmission correlates with more time spent in sniffing the anogenital area of stressed mice, and the appearance of stress buffering correlates with more time engaged in allogrooming from naive partners. Chemical ablation of the olfactory epithelium with dichlobenil or physical separation between social contacts diminishes stress transmission. Together, our data demonstrate that transmitted stress can elicit metaplastic facilitation of LTD induction as authentic stress.SIGNIFICANCE STATEMENT Social animals can acquire information about their environment through interactions with conspecifics. Stress can induce enduring changes in neural activity and synaptic function. Current studies are already unraveling the transmission and buffering of stress responses between individuals, but little is known about the relevant synaptic changes associated with social transmission and buffering of stress. Here, we show that authentic and transmitted stress can prime glutamatergic synapses onto hippocampal CA1 neurons to undergo long-term depression. This hippocampal metaplasticity is bufferable following social interactions with naive partners. Hierarchical status of naive partners strongly affects the social buffering effect on synaptic consequences of stress. This work provides novel insights into the conceptual framework for synaptic changes with social transmission and buffering of stress.

Hydroquinone-induced FOXP3-ADAM17-Lyn-Akt-p21 signaling axis promotes malignant progression of human leukemia U937 cells.

Hydroquinone (1,4-benzenediol; HQ), a major marrow metabolite of the leukemogen benzene, has been proven to evoke benzene-related hematological disorders and myelotoxicity in vitro and in vivo. The goal of the present study was to explore the role of FOXP3 in HQ-induced malignant progression of U937 human leukemia cells. U937 cells were treated with 5 µM HQ for 24 h, and the cells were re-suspended in serum-containing medium without HQ for 2 days. The same procedure was repeated three times, and the resulting U937/HQ cells were maintained in cultured medium containing 5 µM HQ. Proliferation and colony formation of U937/HQ cells were notably higher than those of U937 cells. Ten-eleven translocation methylcytosine dioxygenase-mediated demethylation of the Treg-specific demethylated region in FOXP3 gene resulted in higher FOXP3 expression in U937/HQ cells than in U937 cells. FOXP3-induced miR-183 expression reduced ß-TrCP mRNA stability and suppressed ß-TrCP-mediated Sp1 degradation, leading to up-regulation of Sp1 expression in U937/HQ cells. Sp1 up-regulation further increased ADAM17 and Lyn expression, and ADAM17 up-regulation stimulated Lyn activation in U937/HQ cells. Moreover, U937/HQ cells showed higher Lyn-mediated Akt activation and cytoplasmic p21 expression than U937 cells did. Abolishment of Akt activation decreased cytoplasmic p21 expression in U937/HQ cells. Suppression of FOXP3, ADAM17, and Lyn expression, as well as Akt inactivation, repressed proliferation and clonogenicity of U937/HQ cells. Together with the finding that cytoplasmic p21 shows anti-apoptotic and oncogenic activities in cancer cells, the present data suggest a role of FOXP3/ADAM17/Lyn/Akt/p21 signaling axis in HQ-induced hematological disorders.

The Association Between p38 MAPK-Mediated TNF-α/TNFR2 up-Regulation and 2-(4-Aminophenyl)-7-Methoxybenzothiazole-Induced Apoptosis in Human Leukemia U937 Cells.

The primary cause of treatment failures in acute myeloid leukemia is usually associated with defects in the apoptotic pathway. Several studies suggest that 2-(4-aminophenyl)-7-methoxybenzothiazole (7-OMe-APBT) may potentially induce apoptosis of cancer cells. Thus, the present study was conducted to explore the cytotoxic effect of 7-OMe-APBT on human leukemia U937 cells. The apoptosis of human leukemia U937 cells induced by 7-OMe-APBT was characterized by an increase in mitochondrial membrane depolarization, procaspase-8 degradation, and tBid production. Down-regulation of FADD blocked 7-OMe-APBT-induced procaspase-8 degradation and rescued the viability of 7-OMe-APBT-treated cells, suggesting the involvement of a death receptor-mediated pathway in 7-OMe-APBT-induced cell death. Increased TNF-α expression, TNFR2 expression, and p38 MAPK phosphorylation were noted in 7-OMe-APBT-treated cells. Pretreatment with a p38 MAPK inhibitor abolished 7-OMe-APBT-induced TNF-α and TNFR2 up-regulation. 7-OMe-APBT stimulated p38 MAPK/c-Jun-mediated transcriptional up-regulation of TNFR2, while the increased TNF-α mRNA stability led to TNF-α up-regulation in 7-OMe-APBT-treated cells. Treatment with 7-OMe-APBT up-regulated protein phosphatase 2A catalytic subunit α (PP2Acα) expression via the p38 MAPK/c-Jun/ATF-2 pathway, which, in turn, promoted tristetraprolin (TTP) degradation. Pretreatment with a protein phosphatase 2A inhibitor or TTP over-expression abrogated TNF-α up-regulation in 7-OMe-APBT-treated cells. Abolishment of TNF-α up-regulation or knock-down of TNFR1/TNFR2 by siRNA restored the viability of 7-OMe-APBT-treated cells. Taken together, our data indicate a connection between p38 MAPK-mediated TNF-α and TNFR2 up-regulation and 7-OMe-APBT-induced TNF-α-mediated death pathway activation in U937 cells. The same pathway also elucidates the mechanism underlying 7-OMe-APBT-induced death of human leukemia HL-60 cells.

Amsacrine suppresses matrix metalloproteinase-2 (MMP-2)/MMP-9 expression in human leukemia cells.

This study explores the suppression mechanism of amsacrine (4-(9-Acridinylamino)-N-(methanesulfonyl)-m-anisidine hydrochloride) on matrix metalloproteinase-2 (MMP-2) and MMP-9 expression in human leukemia cells. Amsacrine attenuated cell invasion with decreased MMP-2/MMP-9 protein expression and mRNA levels in U937, Jurkat, HL-60, K562, KU812, and MEG-01 cells. Moreover, amsacrine reduced both MMP-2/MMP-9 promoter luciferase activity and MMP-2/MMP-9 mRNA stability in leukemia cells. Studies on amsacrine-treated U937 cells revealed that amsacrine-elicited ROS generation induced JNK and p38 MAPK activation but reduced the phospho-ERK level. Amsacrine-induced ERK inactivation and p38 MAPK/JNK activation were demonstrated to suppress MMP-2/MMP-9 promoter luciferase activity and promote MMP-2/MMP-9 mRNA decay, respectively. p38 MAPK/JNK activation led to up-regulation of protein phosphatase 2A catalytic subunit α (PP2Acα) in amsacrine-treated U937 cells. Okadaic acid (PP2A inhibitor) treatment increased MMP-2/MMP-9 mRNA stability in amsacrine-treated cells, whereas PP2Acα over-expression increased MMP-2/MMP-9 mRNA decay. Amsacrine-induced MMP-2/MMP-9 down-regulation was also related to PP2Acα up-regulation on Jurkat, HL-60, K562, KU812, and MEG-01 cells. Collectively, our data indicate that amsacrine induces MMP-2/MMP-9 down-regulation via simultaneous suppression of genetic transcription and mRNA stability in human leukemia cells.

p38 MAPK/PP2Acα/TTP pathway on the connection of TNF-α and caspases activation on hydroquinone-induced apoptosis.

This study investigated tumor necrosis factor-α (TNF-α)-mediated death pathway contribution to hydroquinone (HQ) cytotoxicity in human leukemia U937 cells. HQ-induced apoptosis of human leukemia U937 cells was characterized by the increase in mitochondrial membrane depolarization, procaspase-8 degradation and tBid production. Downregulation of Fas-associated death domain protein (FADD) blocked HQ-induced procaspase-8 degradation and rescued the viability of HQ-treated cells, suggesting the involvement of a death receptor-mediated pathway in HQ-induced cell death. HQ induced increased TNF-α mRNA stability led to TNF-α protein expression upregulation, whereas HQ suppressed TNF-α-mediated NFκB pathway activation. HQ elicited protein phosphatase 2A catalytic subunit α (PP2Acα) upregulation via p38 mitogen-activated protein kinase (MAPK)-mediated CREB/c-Jun/ATF-2 phosphorylation, and PP2Acα upregulation was found to promote tristetraprolin (TTP) degradation. Suppression of p38 MAPK activation and protein phosphatase 2A (PP2A) activity abrogated TNF-α upregulation and procaspase degradation in HQ-treated cells. Overexpression of TTP suppressed HQ-induced TNF-α upregulation and restored the viability of HQ-treated cells. Moreover, TTP overexpression increased TNF-α mRNA decay in HQ-treated cells. Taken together, our data indicate that HQ elicits TNF-α upregulation via p38 MAPK/PP2A-mediated TTP downregulation, and suggest that the TNF-α-mediated death pathway is involved in HQ-induced U937 cell death. The same pathway was also proven to be involved in the HQ-induced death of human leukemia HL-60 and Jurkat cells.

Alcohol consumption is inversely associated with stage 3 chronic kidney disease in middle-aged Taiwanese men.

BACKGROUND: Chronic kidney disease (CKD) is a major global public health burden, but there is limited understanding of the relationship of alcohol consumption with CKD. METHODS: In this cross-sectional multivariable study, all participants of a health check-up program in Ditmanson Medical Foundation Chia-Yi Christian Hospital in Taiwan from 2003 to 2009 (15,353 women and 11,900 men) were included for analysis. Estimated glomerular filtration rate was used to define CKD stage and history of alcohol consumption was obtained by self-reporting. Multivariable logistic regression analyses of gender-specific association of alcohol drinking with stage 3 CKD were conducted. A trend tests was conducted to check the dose-response relationship of alcohol consumption with renal disease. A sensitivity test was conducted to rule out the likelihood of reverse causality. RESULTS: The prevalence of stage 3 CKD was lower in drinkers than non-drinkers (p < 0.001) and the percentage of drinkers with stage 3 CKD was less than that of non-drinkers. Multivariable analysis indicated that alcohol consumption was negatively associated with the presence of stage 3 CKD in men (adjusted odds ratio [aOR] for occasional drinking: 0.68, 95% CI: 0.59 ~ 0.78, p < 0.001; aOR for frequent drinking: 0.47, 95% CI: 0.35 ~ 0.63, p < 0.001). Advanced age, hypertension, anemia, BMI of at least 24, hyperuricemia, and proteinuria were also associated with stage 3 CKD in men. Trend tests indicated lower odds of having stage 3 CKD with increased alcohol consumption in both genders. Subgroup analyses and sensitivity tests also indicated the reverse association between alcohol consumption and stage 3 CKD in men regardless of age, diabetes status, and other risky behaviors. CONCLUSIONS: Alcohol consumption was inversely associated with stage 3 CKD in Taiwanese men. However, considering the potential of other health damage with alcohol consumption, the current results should be interpreted cautiously.

The association between hyperuricemia and betel nut chewing in Taiwanese men: a cross-sectional study.

BACKGROUND: Studies have associated betel nut chewing with cancers, metabolic syndrome, cardiovascular disorders, chronic kidney disease, and proteinuria. This study investigated whether hyperuricemia is associated with betel nut chewing in men who participated in a health check-up program. METHODS: From hospital records, we identified a total of 11,991 men who participated in the health check-up program from 2003 to 2009. They were divided into hyperuricemic group and non-hyperuricemic group. Laboratory tests, medical history, and status of cigarette smoking, alcohol consumption, and betel nut chewing were compared between the 2 groups. We calculated odds ratio (OR) and 95% confidence interval (CI) of hyperuricemia in association with betel nut consumption and other factors. RESULTS: Compared with the non-hyperuricemic group, the hyperuricemic group was slightly older (59.4 vs. 58.6 years) but less prevalent with betel nut use (11.8 vs. 13.6%, p = 0.003). Multivariable logistic regression analysis showed that hyperuricemia was negatively associated with betel nut chewing (OR 0.75, 95% CI 0.66-0.84), older age (OR 0.84, 95% CI 0.77-0.93), and diabetes mellitus (OR 0.57, 95% CI 0.50-0.64). On the other hand, hyperuricemia was positively associated with body mass index (OR 1.75, 95% CI 1.62-1.90), drinking (OR 1.36, 95% CI 1.25-1.49), hypertension (OR 1.41, 95% CI 1.30-1.52), mixed hyperlipidemia (OR 1.84, 95% CI 1.33-2.54), chronic kidney disease (OR 3.28, 95% CI 2.94-3.65), and proteinuria (OR 1.22, 95% CI 1.08-1.38). Smoking, hypercholesterolemia, and hypertriglyceridemia had no significant association with hyperuricemia. CONCLUSION: Our data suggest that betel nut chewing is negatively associated with hyperuricemia.

Adaphostin promotes caffeine-evoked autocrine Fas-mediated death pathway activation in Bcr/Abl-positive leukaemia cells.

The present study was conducted to verify whether caffeine is beneficial for improving leukaemia therapy. Co-treatment with adaphostin (a Bcr/Abl inhibitor) was found to potentiate caffeine-induced Fas/FasL up-regulation. Although adaphostin did not elicit ASK1 (apoptosis signal-regulating kinase 1)-mediated phosphorylation of p38 MAPK (mitogen-activated protein kinase) and JNK (c-Jun N-terminal kinase), co-treatment with adaphostin notably increased p38 MAPK/JNK activation in caffeine-treated cells. Suppression of p38 MAPK and JNK abrogated Fas/FasL up-regulation in caffeine- and caffeine/adaphostin-treated cells. Compared with caffeine, adaphostin markedly suppressed Akt/ERK (extracellular-signal-regulated kinase)-mediated MKP-1 (MAPK phosphatase 1) protein expression in K562 cells. MKP-1 down-regulation eventually elucidated the enhanced effect of adaphostin on p38 MAPK/JNK activation and subsequent Fas/FasL up-regulation in caffeine-treated cells. Knockdown of p38α MAPK and JNK1, ATF-2 (activating transcription factor 2) and c-Jun by siRNA (small interfering RNA) proved that p38α MAPK/ATF-2 and JNK1/c-Jun pathways were responsible for caffeine-evoked Fas/FasL up-regulation. Moreover, Ca2+ and ROS (reactive oxygen species) were demonstrated to be responsible for ASK1 activation and Akt/ERK inactivation respectively in caffeine- and caffeine/adaphostin-treated cells. Likewise, adaphostin functionally enhanced caffeine-induced Fas/FasL up-regulation in leukaemia cells that expressed Bcr/Abl. Taken together, the results of the present study suggest a therapeutic strategy in improving the efficacy of adaphostin via Fas-mediated death pathway activation in Bcr/Abl-positive leukaemia.

The Moderating Effect of Compassionate Mindfulness on the Psychological Needs and Emotions of Generation Y in the 21st Century in Taiwan.

During the 2020 COVID-19 pandemic in Taiwan, 6.5% of Generation Y required medical treatment for emotional and stress-related mental disorders. This study explores the moderating effect of mindfulness training on psychological needs and emotions to propose effective measures to promote the mental health of Generation Y. This study was carried out by questionnaire, using the data of respondents born in 1980-1999, collected in three different periods for quantitative analysis with compassionate mindfulness as the main variable. The results show that the compassionate mindfulness effect on emotion regulation varies greatly among different educational levels. However, it still plays a positive role in the psychological needs of Generation Y. Most members of Generation Y who receive compassionate mindfulness training have fewer basic needs and more interpersonal trust. They pay more attention to individual-oriented self-realization. Compassionate mindfulness has a greater positive moderating effect on the mental health of women aged 30-39 and those who are highly educated. Compassionate mindfulness has a more positive moderating effect on the psychological needs of members of Generation Y who were born more recently. During the COVID-19 pandemic, providing compassionate mindfulness has a significant positive effect on the prevention of mental disorders of Generation Y in Taiwan.

Depression Risk Factors for Knowledge Workers in the Post-Capitalist Society of Taiwan.

This study aimed to examine the depression risk factors for knowledge workers aged 20-64 in the post-capitalist society of Taiwan. Interview data from 2014 and 2019 were adopted for quantitative analysis of the depression risk by demographic and individual characteristics. The results showed that the depression risks of knowledge workers were not affected by demographic variables in a single period. From 2014 to 2019, the prevalence of high depression risk in knowledge workers aged 20-64 years increased over time. The more attention is paid to gender equality in society, the less the change in the gender depression index gap may be seen. Positive psychological state and family relationships are both depression risk factors and depression protective factors. Being male, married, religious, and aged 45-49 years old were found to be critical risk factors. Variables of individual characteristics could effectively predict depression risk.

Suppression of ADAM17-mediated Lyn/Akt pathways induces apoptosis of human leukemia U937 cells: Bungarus multicinctus protease inhibitor-like protein-1 uncovers the cytotoxic mechanism.

Cell surface proteases have been demonstrated to play an important role in facilitating cell invasion into the extracellular matrix and may contribute significantly to extracellular matrix degradation by metastatic cancer cells. Abundant expression of these enzymes is associated with poor prognosis. Thus, protease inhibitors that repress cell surface proteases may be applicable to cancer therapy. Because soybean Kunitz-type trypsin inhibitor has been found to induce apoptotic death of human leukemia Jurkat cells, anti-leukemia activity of Bungarus multicinctus protease inhibitor-like protein-1 (PILP-1) is thus examined. PILP-1 induced apoptosis of human leukemia U937 cells, characteristic of loss of mitochondrial membrane potential, degradation of procaspase-8, and production of t-Bid. FADD down-regulation neither restored viability of PILP-1-treated cells nor attenuated production of active caspase-8 and t-Bid in PILP-1-treated cells, suggesting that the death receptor-mediated pathway was not involved in the cytotoxicity of PILP-1. It was found that PILP-1-evoked p38 MAPK activation and ERK inactivation led to PILP-1-induced cell death and down-regulation of ADAM17. Knockdown of ADAM17 by siRNA induced death of U937 cells and inactivation of Lyn and Akt. Immunoprecipitation suggested that ADAM17 and Lyn form complexes. Overexpression of ADAM17, LynY507F (gain of function), and constitutively active Akt suppressed the cytotoxic effects of PILP-1. PILP-1-elicited inactivation of Lyn and Akt was abrogated in cells with overexpressed ADAM17 or LynY507F. Taken together, our data indicate that ADAM17-mediated activation of Lyn/Akt maintains the viability of U937 cells and that suppression of the pathway is responsible for PILP-1-induced apoptosis.

Association of betel nut chewing with chronic kidney disease: a retrospective 7-year study in Taiwan.

AIM: Only few studies have reported that betel nut (BN) chewing is independently associated with chronic kidney disease (CKD); however, the sample size was relatively small. This study was to explore further the association between BN chewing and CKD using a larger case series. METHODS: We retrospectively reviewed the records of a health check-up program from 2003 to 2009. Laboratory tests, medical history and status of cigarette smoking, alcohol drinking and BN chewing were compared between CKD and non-CKD groups. We checked interaction effects between BN chewing and all other covariates, and conducted multivariate logistic regression analysis to explore the risk of CKD with BN chewing. RESULTS: A total of 27 482 participants (15 491 females and 11 991 males, mean age 58.02 ± 11.85 years) were included in the study, of whom 4519 (16.4%) had CKD and 1608 (5.9%) chewed BN. CKD prevalence in the chewers was higher than in the non-chewers in all age groups per decade. BN chewing was significantly associated with CKD in overall subjects (odds ratio (OR) = 1.23, P = 0.027) and also in the male (OR = 1.23, P = 0.035), non-drinking (OR = 1.62, P = 0.000), non-diabetic (OR = 1.27, P = 0.021), and non-proteinuric groups (OR = 1.30, P = 0.013). This relationship was insignificant in female, drinking, diabetic and proteinuric groups. CONCLUSION: The association between BN chewing and CKD seemed conditional on demographics, health behaviours, and underlying co-morbidities. This association should be interpreted cautiously.

A reporter system for enriching CRISPR/Cas9 knockout cells in technically challenging settings like patient models.

CRISPR/Cas9 represents a valuable tool to determine protein function, but technical hurdles limit its use in challenging settings such as cells unable to grow in vitro like primary leukemia cells and xenografts derived thereof (PDX). To enrich CRISPR/Cas9-edited cells, we improved a dual-reporter system and cloned the genomic target sequences of the gene of interest (GOI) upstream of an out-of-frame fluorochrome which was expressed only upon successful gene editing. To reduce rounds of in vivo passaging required for PDX leukemia growth, targets of 17 GOI were cloned in a row, flanked by an improved linker, and PDX cells were lentivirally transduced for stable expression. The reporter enriched scarce, successfully gene-edited PDX cells as high as 80%. Using the reporter, we show that KO of the SRC-family kinase LYN increased the response of PDX cells of B precursor cell ALL towards Vincristine, even upon heterozygous KO, indicating haploinsufficiency. In summary, our reporter system enables enriching KO cells in technically challenging settings and extends the use of gene editing to highly patient-related model systems.

In vivo inducible reverse genetics in patients' tumors to identify individual therapeutic targets.

High-throughput sequencing describes multiple alterations in individual tumors, but their functional relevance is often unclear. Clinic-close, individualized molecular model systems are required for functional validation and to identify therapeutic targets of high significance for each patient. Here, we establish a Cre-ERT2-loxP (causes recombination, estrogen receptor mutant T2, locus of X-over P1) based inducible RNAi- (ribonucleic acid interference) mediated gene silencing system in patient-derived xenograft (PDX) models of acute leukemias in vivo. Mimicking anti-cancer therapy in patients, gene inhibition is initiated in mice harboring orthotopic tumors. In fluorochrome guided, competitive in vivo trials, silencing of the apoptosis regulator MCL1 (myeloid cell leukemia sequence 1) correlates to pharmacological MCL1 inhibition in patients´ tumors, demonstrating the ability of the method to detect therapeutic vulnerabilities. The technique identifies a major tumor-maintaining potency of the MLL-AF4 (mixed lineage leukemia, ALL1-fused gene from chromosome 4) fusion, restricted to samples carrying the translocation. DUX4 (double homeobox 4) plays an essential role in patients' leukemias carrying the recently described DUX4-IGH (immunoglobulin heavy chain) translocation, while the downstream mediator DDIT4L (DNA-damage-inducible transcript 4 like) is identified as therapeutic vulnerability. By individualizing functional genomics in established tumors in vivo, our technique decisively complements the value chain of precision oncology. Being broadly applicable to tumors of all kinds, it will considerably reinforce personalizing anti-cancer treatment in the future.

Caffeine induces matrix metalloproteinase-2 (MMP-2) and MMP-9 down-regulation in human leukemia U937 cells via Ca2+/ROS-mediated suppression of ERK/c-fos pathway and activation of p38 MAPK/c-jun pathway.

Caffeine attenuated invasion of human leukemia U937 cells with characteristic of decreased protein expression and mRNA levels of matrix metalloproteinase-2 (MMP-2) and MMP-9. Down-regulation of MMP-2 and MMP-9 in U937 cells was abrogated by abolishment of caffeine-elicited increase in intracellular Ca(2+) concentration and ROS generation. Pretreatment with BAPTA-AM (Ca(2+) chelator) and N-acetylcysteine (ROS scavenger) abolished caffeine-induced ERK inactivation and p38 MPAK activation. Moreover, caffeine treatment led to MAPK phosphatase-1 (MKP-1) down-regulation and protein phosphatase 2A catalytic subunit (PP2Ac) up-regulation, which were involved in cross-talk between p38 MAPK and ERK. Transfection of constitutively active MEK1 or pretreatment with SB202190 (p38 MAPK inhibitor) restored MMP-2 and MMP-9 protein expression in caffeine-treated cells. Caffeine treatment repressed ERK-mediated c-Fos phosphorylation but evoked p38 MAPK-mediated c-Jun phosphorylation. Knock-down of c-Fos and c-Jun by siRNA reflected that c-Fos counteracted the effect of c-Jun on MMP-2/MMP-9 down-regulation. Taken together, our data indicate that MMP-2/MMP-9 down-regulation in caffeine-treated U937 cells is elicited by Ca(2+)/ROS-mediated suppression of ERK/c-Fos pathway and activation of p38 MAPK/c-Jun pathway.

Suppression of ERK signaling evokes autocrine Fas-mediated death in arachidonic acid-treated human chronic myeloid leukemia K562 cells.

Arachidonic acid (AA)-induced apoptotic death of K562 cells (human chronic myeloid leukemic cells) was characteristic of reactive oxygen species (ROS) generation and mitochondrial depolarization. N-Acetylcysteine pretreatment rescued viability of AA-treated cells and abolished mitochondrial depolarization. In contrast to no significant changes in phospho-JNK and phospho-ERK levels, AA evoked notable activation of p38 MAPK. Unlike that of JNK and p38 MAPK, ERK suppression further reduced the viability of AA-treated cells. Increases in Fas/FasL protein expression, caspase-8 activation, the production of tBid and the loss of mitochondrial membrane potential were noted with K562 cells that were treated with a combination of U0126 and AA. Down-regulation of FADD attenuated U0126-evoked degradation of procaspase-8 and Bid. Abolition of p38 MAPK activation abrogated U0126-elicited Fas/FasL up-regulation in AA-treated cells. U0126 pretreatment suppressed c-Fos phosphorylation but increased p38 MAPK-mediated c-Jun phosphorylation. Knock-down of c-Fos and c-Jun protein expression by siRNA suggested that c-Fos counteracted the effect of c-Jun on Fas/FasL up-regulation. Taken together, our data indicate that AA induces the ROS/mitochondria-dependent death pathway and blocks the ERK pathway which enhances the cytotoxicity of AA through additionally evoking an autocrine Fas-mediated apoptotic mechanism in K562 cells.

Calcium-stimulated mitogen-activated protein kinase activation elicits Bcl-xL downregulation and Bak upregulation in notexin-treated human neuroblastoma SK-N-SH cells.

Notechis scutatus scutatus notexin induced apoptotic death of SK-N-SH cells accompanied with downregulation of Bcl-xL, upregulation of Bak, mitochondrial depolarization, and ROS generation. Upon exposure to notexin, Ca(2+)-mediated JNK and p38 MAPK activation were observed in SK-N-SH cells. Production of ROS was a downstream event followed by Ca(2+)-mediated mitochondrial alteration. Notexin-induced cell death, mitochondrial depolarization, and ROS generation were suppressed by SB202190 (p38 MAPK inhibitor) and SP600125 (JNK inhibitor). Moreover, phospho-p38 MAPK and phospho-JNK were proved to be involved in Bcl-xL degradation, and overexpression of Bcl-xL attenuated the cytotoxic effect of notexin. Bak upregulation was elicited by p38 MAPK-mediated ATF-2 activation and JNK-mediated c-Jun activation. Suppression of Bak upregulation by ATF-2 siRNA or c-Jun siRNA attenuated notexin-evoked mitochondrial depolarization and rescued viability of notexin-treated cells. Taken together, our data indicate that notexin-induced apoptotic death of SK-N-SH cells is mediated through mitochondrial alteration triggering by Ca(2+)-evoked p38 MAPK/ATF-2 and JNK/c-Jun signaling pathways.

Taiwan cobra phospholipase A2-elicited JNK activation is responsible for autocrine fas-mediated cell death and modulating Bcl-2 and Bax protein expression in human leukemia K562 cells.

Phospholipase A(2) (PLA(2)) from Naja naja atra venom induced apoptotic death of human leukemia K562 cells. Degradation of procaspases, production of tBid, loss of mitochondrial membrane potential, Bcl-2 degradation, mitochondrial translocation of Bax, and cytochrome c release were observed in PLA(2)-treated cells. Moreover, PLA(2) treatment increased Fas and FasL protein expression. Upon exposure to PLA(2), activation of p38 MAPK (mitogen-activated protein kinase) and JNK (c-Jun NH(2)-terminal kinase) was found in K562 cells. SB202190 (p38 MAPK inhibitor) pretreatment enhanced cytotoxic effect of PLA(2) and led to prolonged JNK activation, but failed to affect PLA(2)-induced upregulation of Fas and FasL protein expression. Sustained JNK activation aggravated caspase8/mitochondria-dependent death pathway, downregulated Bcl-2 expression and increased mitochondrial translocation of Bax. SP600125 (JNK inhibitor) abolished the cytotoxic effect of PLA(2) and PLA(2)-induced autocrine Fas death pathway. Transfection ASK1 siRNA and overexpression of dominant negative p38alpha MAPK proved that ASK1 pathway was responsible for PLA(2)-induced p38 MAPK and JNK activation and p38alpha MAPK activation suppressed dynamically persistent JNK activation. Downregulation of FADD abolished PLA(2)-induced procaspase-8 degradation and rescued viability of PLA(2)-treated cells. Taken together, our results indicate that JNK-mediated autocrine Fas/FasL apoptotic mechanism and modulation of Bcl-2 family proteins are involved in PLA(2)-induced death of K562 cells.

Taiwan cobra phospholipase A2 elicits posttranscriptional up-regulation of ADAM17 in human neuroblastoma SK-N-SH cells.

Taiwan cobra phospholipase A(2) (PLA(2)) treatment promoted proADAM17 processing into mature ADAM17 in human neuroblastoma SK-N-SH cells. The abolishment of catalytic activity caused a drastic drop in the PLA(2) ability to induce ADAM17 maturation, and lysophosphatidylcholine treatment mimicked the effect of PLA(2). ADAM17 activity measurement, ADAM17 cell surface levels, TNFR2 ectodomain shedding, and ADAM17 mRNA transcription supported that posttranscriptional up-regulation of ADAM17 occurred in PLA(2)-treated SK-N-SH cells. PLA(2) treatment induced p38 MAPK activation and ERK inactivation. p38 MAPK activation suppression by SB202190 (p38 MAPK inhibitor) abolished posttranscriptional up-regulation of ADAM17 in PLA(2)-treated cells, while treatment with U0126 (MEK1 and MEK2 inhibitor) increased ADAM17 maturation in SK-N-SH cells. Constitutively active MEK1 expression abrogated PLA(2)-induced ADAM17 maturation. Taken together, our data indicate that PLA(2)-evoked p38 MAPK activation and ERK inactivation are involved in ADAM17 posttranscriptional up-regulation, and suggest that the action of PLA(2) is catalytic activity-dependent.