P38 Mitogen-activated Protein Kinase Cascade Research Articles

Mitochondrial p38 Mitogen-Activated Protein Kinase: Insights into Its Regulation of and Role in LONP1-Deficient Nematodes.

p38 Mitogen-Activated Protein Kinase (MAPK) cascades are central regulators of numerous physiological cellular processes, including stress response signaling. In C. elegans, mitochondrial dysfunction activates a PMK-3/p38 MAPK signaling pathway (MAPKmt), but its functional role still remains elusive. Here, we demonstrate the induction of MAPKmt in worms deficient in the lonp-1 gene, which encodes the worm ortholog of mammalian mitochondrial LonP1. This induction is subjected to negative regulation by the ATFS-1 transcription factor through the CREB-binding protein (CBP) ortholog CBP-3, indicating an interplay between both activated MAPKmt and mitochondrial Unfolded Protein Response (UPRmt) surveillance pathways. Our results also reveal a genetic interaction in lonp-1 mutants between PMK-3 kinase and the ZIP-2 transcription factor. ZIP-2 has an established role in innate immunity but can also modulate the lifespan by maintaining mitochondrial homeostasis during ageing. We show that in lonp-1 animals, ZIP-2 is activated in a PMK-3-dependent manner but does not confer increased survival to pathogenic bacteria. However, deletion of zip-2 or pmk-3 shortens the lifespan of lonp-1 mutants, suggesting a possible crosstalk under conditions of mitochondrial perturbation that influences the ageing process. Furthermore, loss of pmk-3 specifically diminished the extreme heat tolerance of lonp-1 worms, highlighting the crucial role of PMK-3 in the heat shock response upon mitochondrial LONP-1 inactivation.

LIM domain only 7 negatively controls nonalcoholic steatohepatitis in the setting of hyperlipidemia.

Hyperlipidemia has been extensively recognized as a high-risk factor for NASH; however, clinical susceptibility to NASH is highly heterogeneous. The key controller(s) of NASH susceptibility in patients with hyperlipidemia has not yet been elucidated. Here, we aimed to reveal the key regulators of NASH in patients with hyperlipidemia and to explore its role and underlying mechanisms. To identify the predominant suppressors of NASH in the setting of hyperlipidemia, we collected liver biopsy samples from patients with hyperlipidemia, with or without NASH, and performed RNA-sequencing analysis. Notably, decreased Lineage specific Interacting Motif domain only 7 (LMO7) expression robustly correlated with the occurrence and severity of NASH. Although overexpression of LMO7 effectively blocked hepatic lipid accumulation and inflammation, LMO7 deficiency in hepatocytes greatly exacerbated diet-induced NASH progression. Mechanistically, lysine 48 (K48)-linked ubiquitin-mediated proteasomal degradation of tripartite motif-containing 47 (TRIM47) and subsequent inactivation of the c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK) cascade are required for the protective function of LMO7 in NASH. These findings provide proof-of-concept evidence supporting LMO7 as a robust suppressor of NASH in the context of hyperlipidemia, indicating that targeting the LMO7-TRIM47 axis is a promising therapeutic strategy for NASH.

Embryonic Exposure to UV-328 Impairs the Cell Cycle in Zebrafish (Danio rerio) by Inhibiting the p38 MAPK/p53/Gadd45a Signaling Pathway.

The benzotriazole UV stabilizer UV-328 is well known for its potent antioxidative properties; however, there are concerns about how it may affect signaling nodes and lead to negative consequences. This study identified the key signaling cascades involved in oxidative stress in zebrafish (Danio rerio) larvae and evaluated the cell cycle arrests and associated developmental alternations. Exposure to UV-328 at 0.25, 0.50, 1.00, 2.00, and 4.00 μg/L downregulated gene expression associated with oxidative stress (cat, gpx, gst, and sod) and apoptosis (caspase-3, caspase-6, caspase-8, and caspase-9) at 3 days postfertilization (dpf). The transcriptome aberration in zebrafish with disrupted p38 mitogen-activated protein kinase (MAPK) cascades was validated based on decreased mRNA expressions of p38 MAPK (0.36-fold), p53 (0.33-fold), and growth arrest and DNA damage-inducible protein 45 α (Gadd45a) (0.52-fold) after a 3- and 14-day exposure alongside a correspondingly decreased protein expression. The percentage of cells in the Gap 1 (G1) phase increased from 69.60% to a maximum of 77.07% (p < 0.05) in the 3 dpf embryos. UV-328 inhibited the p38 MAPK/p53/Gadd45a regulatory circuit but promoted G1 phase cell cycle arrest, abnormally accelerating the embryo hatching and heart rate. This study provided mechanistic insights that enrich the risk profiles of UV-328.

Sonic hedgehog promotes synovial inflammation and articular damage through p38 mitogen-activated protein kinase signaling in experimental arthritis

Activated fibroblast-like synoviocytes (FLS) play a pivotal role in synovial inflammation and joint destruction of rheumatoid arthritis (RA). The mechanisms by which sonic hedgehog (SHH) signaling promotes RA FLS-mediated chronic inflammation and tissue damage are not fully understood. The present study aims to determine the role of SHH signaling in the pathogenesis of RA and to explore the potential mechanism(s). We found that the components of SHH signaling were highly expressed in FLS and synovial tissue from patients with RA and in the joint tissue of collagen-induced arthritis (CIA) mice. Overexpression of SHH aggravated the synovial inflammation and joint destruction of CIA and exacerbated cartilage degradation in the cartilage and RA FLS-engrafted severe combined immunodeficiency (SCID) model. Conversely, inhibition of SHH signaling significantly alleviated arthritis severity and reduced cartilage destruction caused by the invasion of RA FLS in vivo. Moreover, we found that p38 mitogen-activated protein kinase (MAPK) cascade was regulated by SHH signaling in RA FLS and the level of phospho-p38 in the joint tissue of CIA was decreased after blockade of SHH signaling. Inhibition of p38 MAPK abolished the effect of SHH overexpression on synovial inflammation and articular destruction of CIA and suppressed the aggressive properties of RA FLS, which were promoted by SHH agonist. In conclusion, our study suggests that SHH signaling aggravates synovial inflammation and joint destruction of experimental arthritis and promotes the abnormal behavior of RA FLS in a p38-dependent manner. SHH-p38 MAPK signaling could be a potential target for the treatment of RA.

MAPK Signaling Pathway Is Essential for Female Reproductive Regulation in the Cabbage Beetle, Colaphellus bowringi.

The mitogen-activated protein kinase (MAPK) signaling pathway is a well-conserved intracellular signal transduction pathway, and has important roles in mammalian reproduction. However, it is unknown whether MAPK also regulates insect reproductive mechanisms. Therefore, we investigated the role of the MAPK signaling pathway in ovarian growth and oviposition in the cabbage beetle Colaphellus bowringi, an economically important pest of Cruciferous vegetables. As an initial step, 14 genes from the extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK (P38) cascades were knocked down using RNA interference (RNAi). The results revealed that RNAi knockdown of MAPK-ERK kinase (MEK), ERK, Kinase suppressor of RAS 2 (KSR2), and P38 induced ovarian development stagnation, low fecundity, and decreased longevity, which indicate that ERK and P38 signaling pathways are important for female C. bowringi survival and reproduction. The potential regulatory role of ERK and P38 pathways in the female reproductive process was investigated using quantitative real-time PCR. We found that ERK pathway possibly regulated ecdysone biosynthesis and P38 pathway possibly involved in the germline stem cell (GSC) development and differentiation. Our findings demonstrated the importance of the MAPK signaling pathway in the female reproduction of insects, and further enhanced the molecular mechanism of female reproductive regulation in insects.

Tribbles pseudokinase NIPI-3 regulates intestinal immunity in Caenorhabditis elegans by controlling SKN-1/Nrf activity.

In Caenorhabditis elegans, ROS generated in response to intestinal infection induces SKN-1, a protective transcription factor homologous to nuclear factor erythroid 2-related factor 1 or 2 (NRF1/2) in mammals. Many factors regulate SKN-1, including the p38 mitogen-activated protein kinase (MAPK) cascade that activates SKN-1 by phosphorylation. In this work, another positive regulator of SKN-1 is identified: NIPI-3, a Tribbles pseudokinase. NIPI-3 has been reported to protect against intestinal infection by negatively regulating the CCAT enhancer binding protein (C/EBP) bZIP transcription factor CEBP-1. Here we demonstrate that CEBP-1 positively regulates the vhp-1 transcript, which encodes a phosphatase that dephosphorylates the p38 MAPK called PMK-1. The increased levels of VHP-1 caused by CEBP-1 transcriptional enhancement result in less PMK-1 phosphorylation, affecting SKN-1 activity and intestinal resistance to the pathogen. Thedata support a model in which NIPI-3's negative regulation of CEBP-1 decreases VHP-1 phosphatase activity, allowing increased stimulation of SKN-1 activity by the p38 MAPK phosphorylation cascade in the intestine.

Nuclear P38: Roles in Physiological and Pathological Processes and Regulation of Nuclear Translocation.

The p38 mitogen-activated protein kinase (p38MAPK, termed here p38) cascade is a central signaling pathway that transmits stress and other signals to various intracellular targets in the cytoplasm and nucleus. More than 150 substrates of p38α/β have been identified, and this number is likely to increase. The phosphorylation of these substrates initiates or regulates a large number of cellular processes including transcription, translation, RNA processing and cell cycle progression, as well as degradation and the nuclear translocation of various proteins. Being such a central signaling cascade, its dysregulation is associated with many pathologies, particularly inflammation and cancer. One of the hallmarks of p38α/β signaling is its stimulated nuclear translocation, which occurs shortly after extracellular stimulation. Although p38α/β do not contain nuclear localization or nuclear export signals, they rapidly and robustly translocate to the nucleus, and they are exported back to the cytoplasm within minutes to hours. Here, we describe the physiological and pathological roles of p38α/β phosphorylation, concentrating mainly on the ill-reviewed regulation of p38α/β substrate degradation and nuclear translocation. In addition, we provide information on the p38α/β ’s substrates, concentrating mainly on the nuclear targets and their role in p38α/β functions. Finally, we also provide information on the mechanisms of nuclear p38α/β translocation and its use as a therapeutic target for p38α/β-dependent diseases.

Mapping p38α mitogen-activated protein kinase signaling by proximity-dependent labeling.

Mitogen-activated protein (MAP) kinase signaling is central to multiple cellular responses and processes. MAP kinase p38α is the best characterized member of the p38 MAP kinase family. Upstream factors and downstream targets of p38α have been identified in the past by conventional methods such as coimmunoprecipitation. However, a complete picture of its interaction partners and substrates in cells is lacking. Here, we employ a proximity-dependent labeling approach using biotinylation tagging to map the interactome of p38α in cultured 293T cells. Fusing the advanced biotin ligase BioID2 to the N-terminus of p38α, we used mass spectrometry to identify 37 biotin-labeled proteins that putatively interact with p38α. Gene ontology analysis confirms known upstream and downstream factors in the p38 MAP kinase cascade (e.g., MKK3, MAPKAPK2, TAB2, and c-jun). We furthermore identify a cluster of zinc finger (ZnF) domain-containing proteins that is significantly enriched among proximity-labeled interactors and is involved in gene transcription and DNA damage response. Fluorescence imaging and coimmunoprecipitation with overexpressed p38α in cells supports an interaction of p38α with ZnF protein XPA, a key factor in the DNA damage response, that is promoted by UV irradiation. These results define an extensive network of interactions of p38α in cells and new direct molecular targets of MAP kinase p38α in gene regulation and the DNA damage response.

Early-life long-term exposure to ZnO nanoparticles suppresses innate immunity regulated by SKN-1/Nrf and the p38 MAPK signaling pathway in Caenorhabditis elegans

The widespread use of zinc oxide nanoparticles (ZnO-NPs) has led to their release into the environment, and they thus represent a potential risk for both humans and ecosystems. However, the negative impact of ZnO-NPs on the immune system, especially in relation to host defense against pathogenic infection and its underlying regulatory mechanisms, remains largely unexplored. This study investigated the effects of early-life long-term ZnO-NPs exposure (from L1 larvae to adults) on innate immunity and its underlying mechanisms using a host–pathogen Caenorhabditis elegans model, and this was compared with the effect of ionic Zn. The results showed that the ZnO-NPs taken up by C. elegans primarily accumulated in the intestine and that early-life long-term ZnO-NPs exposure at environmentally relevant concentrations (50 and 500 μg/L) decreased the survival of wild-type C. elegans when faced with pathogenic Pseudomonas aeruginosa PA14 infection. Early-life long-term ZnO-NPs (500 μg/L) exposure significantly increased (by about 3-fold) the accumulation of live P. aeruginosa PA14 colonies in the intestine of C. elegans. In addition, ZnO-NPs (500 μg/L) inhibited the intestinal nuclear translocation of SKN-1 and also downregulated gcs-1 gene expression, which is an SKN-1 target gene. Further evidence revealed that early-life long-term exposure to ZnO-NPs (500 μg/L) did not increase susceptibility to mutation among the genes (pmk-1, sek-1, and nsy-1) encoding the p38 mitogen-activated protein kinase (MAPK) cascade in response to P. aeruginosa PA14 infection, though ZnO-NPs significantly decreased the mRNA levels of pmk-1, sek-1, and nsy-1. This study provides regulatory insight based on evidence that ZnO-NPs suppress the innate immunity of C. elegans and highlights the potential health risks of certain environmental nanomaterials, including ZnO-NPs, in terms of their immunotoxicity at environmentally relevant concentrations.

Молекулярные механизмы апоптоза нейтрофилов (обзор литературы)

В обзоре представлены современные данные о механизмах инициации, регуляции и выполнении процесса апоптоза нейтрофилов с участием «рецепторов смерти», митохондрий, белков семейства Bcl-2, PI3-K (phosphatidylinositol 3-kinase), протеинкиназных каскадов p38 MAPK (mitogen-activated protein kinase), ERK (extracellular signal regulated kinase) и JNK (c-Jun N-terminal kinase), протеинкиназ А, В и С, сAMP, белков теплового шока, NF-kB (nuclear factor-kB), кальпаинов, каспаз и их ингибиторов, активных форм кислорода и других факторов. Предложена гипотетическая модель вовлечения апоптотических процессов в регуляцию дифференцировки и реактивности нейтрофилов. This review presented recent data on initiation, regulation, and execution of neutrophil apoptosis with participation of «death receptors», mitochondria, Bcl-2 family proteins, PI3-K (phosphatidylinositol 3-kinase), p38 MAPK (mitogen-activated protein kinase), ERK (extracellular signal regulated kinase) and JNK (c-Jun N-terminal kinase) cascades, protein kinases A, B and C, сAMP, heat shock proteins, NF-kB (nuclear factor-kB), calpains, caspases and theirs inhibitors, reactive oxygen species, and other factors. A speculative model of the apoptotic processes involvement in the regulation of neutrophil differentiation and reactivity was proposed.

The collagen-derived compound collagen tripeptide induces collagen expression and extends lifespan via a conserved p38 mitogen-activated protein kinase cascade

The skin consists mostly of extracellular matrix (ECM) composed mainly of collagen, which provides a protective barrier from the environment. The skin continuously experiences harmful stress and damage. As aging progresses, the expression of various genes declines, and physiological functional deterioration occurs. The reduction of collagen accompanying aging impairs the barrier function of the skin and weakens protection from stressors. In the nematode Caenorhabditis elegans, ECM proteins turn over during aging. Older worms of longevity mutants exhibit increased collagen expression, whereas knockdown of collagen genes shortens lifespan. However, it is unclear whether the progression of aging can be delayed by increasing collagen production via an external stimulus. In this study, we examined the effects of collagen tripeptide (CTP), a collagen-derived compound, on lifespan and aging. Our results showed that CTP upregulated collagen genes via the p38 mitogen-activated protein kinase (MAPK)/SKN-1 pathway. Moreover, CTP extended lifespan and delayed aging through p38 MAPK/SKN-1 pathway. In addition, CTP also induced collagen expression via the p38 MAPK pathway in mammals. Our findings supported that external stimuli such as CTP could promote ECM youthfulness using a conserved signaling pathway, thereby contributing to suppression of aging.

Ral Signals through a MAP4 Kinase-p38 MAP Kinase Cascade in C. elegans Cell Fate Patterning

C.elegans vulval precursor cell (VPC) fates are patterned by an epidermal growth factor (EGF) gradient. High-dose EGF induces 1° VPC fate, and lower dose EGF contributes to 2° fate in support ofLIN-12/Notch. We previously showed that the EGF 2°-promoting signal is mediated by LET-60/Ras switching effectors, from the canonical Raf-MEK-ERK mitogen-activated protein (MAP) kinase cascade that promotes 1° fate to the non-canonical RalGEF-Ral that promotes 2° fate. Of oncogenic Ras effectors, RalGEF-Ral is by far the least well understood. We use genetic analysis to identify an effector cascade downstream of C.elegans RAL-1/Ral, starting with an established Ral binding partner, Exo84 of the exocyst complex. Additionally, RAL-1 signals through GCK-2, a citron-N-terminal-homology-domain-containing MAP4 kinase, and PMK-1/p38 MAP kinase cascade to promote 2° fate. Our study delineates a Ral-dependent developmental signaling cascade invivo, thus providing the mechanism by which lower EGF dose is transduced.

The p38 pathway, a major pleiotropic cascade that transduces stress and metastatic signals in endothelial cells.

By gating the traffic of molecules and cells across the vessel wall, endothelial cells play a central role in regulating cardiovascular functions and systemic homeostasis and in modulating pathophysiological processes such as inflammation and immunity. Accordingly, the loss of endothelial cell integrity is associated with pathological disorders that include atherosclerosis and cancer. The p38 mitogen-activated protein kinase (MAPK) cascades are major signaling pathways that regulate several functions of endothelial cells in response to exogenous and endogenous stimuli including growth factors, stress and cytokines. The p38 MAPK family contains four isoforms p38α, p38β, p38γ and p38δ that are encoded by four different genes. They are all widely expressed although to different levels in almost all human tissues. p38α/MAPK14, that is ubiquitously expressed is the prototype member of the family and is referred here as p38. It regulates the production of inflammatory mediators, and controls cell proliferation, differentiation, migration and survival. Its activation in endothelial cells leads to actin remodeling, angiogenesis, DNA damage response and thereby has major impact on cardiovascular homeostasis, and on cancer progression. In this manuscript, we review the biology of p38 in regulating endothelial functions especially in response to oxidative stress and during the metastatic process.

Mitochondria and MAPK cascades modulate endosulfan-induced germline apoptosis in Caenorhabditis elegans.

Endosulfan as a new member of persistent organic pollutants has been shown to induce apoptosis in various animal models. However, the mechanism underlying endosulfan-induced apoptosis has not been well elucidated thus far. Caenorhabditis elegans N2 wild type and mutant strains were used in the present study to clarify the roles of the mitochondria, the insulin/insulin-like growth factor-1 (IGF-1) signaling pathway, and mitogen-activated protein kinase (MAPK) cascades in α-endosulfan-induced apoptosis. Our results demonstrated a dose- and time-dependent increase of apoptosis in the meiotic zone of the gonad of C. elegans exposed to graded concentrations of endosulfan. The expression levels of sod-3, localized in the mitochondrial matrix, increased greatly after endosulfan exposure. A significant increase in germ cell apoptosis was observed in abnormal methyl viologen sensitivity-1 (mev-1(kn-1)) mutants (with abnormal mitochondrial respiratory chain complex II and higher ROS levels) compared to that in N2 at equal endosulfan concentrations. We found that the insulin/IGF-1 signaling pathway and its downstream Ras/ERK/MAPK did not participate in the endosulfan-induced apoptosis. However, the apoptosis in the loss-of-function strains of JNK and p38 MAPK signaling pathways was completely or mildly suppressed under endosulfan stress. The apoptotic effects of endosulfan were blocked in the mutants of jnk-1/JNK-MAPK, sek-1/MAP2K, and pmk-1/p38-MAPK, suggesting that these downstream genes play an essential role in endosulfan-induced germ cell apoptosis. In contrast, the mkk-4/MAP2K and nsy-1/MAP3K were only partially involved in the apoptosis induction. Our data provide evidence that endosulfan increases germ cell apoptosis, which is regulated by mitochondrial function, JNK and p38 MAPK cascades. These findings contribute to the understanding of the signal transduction pathways involved in endosulfan-induced apoptosis.

Activation of c-Jun N-terminal kinase by Akabane virus is required for apoptosis

Akabane virus (AKAV) belongs to the Simbu serogroup of the genus Orthobunyavirus in the family Bunyaviridae. It has been shown that AKAV induces apoptosis in mammalian cells. It is necessary to understand the signaling pathways involved in AKAV-induced apoptosis to further elucidate the molecular virology of AKAV. c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) are mediators of apoptosis; therefore, we investigated the roles of JNK and p38 MAPK cascades in AKAV-infected cells. We found that JNK and p38 MAPK as well as their downstream substrates, c-Jun and heat shock protein 27 (HSP27), were phosphorylated in response to AKAV infection. A JNK inhibitor (SP600125) inhibited AKAV-mediated apoptosis whereas a p38 MAPK inhibitor (SB203580) did not. We conclude that AKAV infection activates the JNK and p38 MAPK signaling pathways, and the JNK cascade plays a crucial role in AKAV-induced apoptosis in vitro.

JNK and p38 mitogen-activated protein kinase pathways contribute to porcine epidemic diarrhea virus infection

The mitogen-activated protein kinase (MAPK) pathways, which are central building blocks in the intracellular signaling network, are often manipulated by viruses of diverse families to favor their replication. Among the MAPK family, the extracellular signal-regulated kinase (ERK) pathway is known to be modulated during the infection with porcine epidemic diarrhea virus (PEDV); however, involvement of stress-activated protein kinases (SAPKs) comprising p38 MAPK and c-Jun NH2-terminal kinase (JNK) remains to be determined. Therefore, in the present study, we investigated whether activation of p38 MAPK and JNK cascades is required for PEDV replication. Our results showed that PEDV activates p38 MAPK and JNK1/2 up to 24h post-infection, whereas, thereafter their phosphorylation levels recede to baseline levels or even fall below them. Notably, UV-irradiated inactivated PEDV, which can enter cells but cannot replicate inside them, failed to induce phosphorylation of p38 MAPK and JNK1/2 suggesting that viral biosynthesis is essential for activation of these kinases. Treatment of cells with selective p38 or JNK inhibitors markedly impaired PEDV replication in a dose-dependent manner and these antiviral effects were found to be maximal during the early times of the infection. Furthermore, direct pharmacological inhibition of p38 MAPK or JNK1/2 activation resulted in a significant reduction of viral RNA synthesis, viral protein expression, and progeny release. However, independent treatments with either SAPK inhibitor did not inhibit PEDV-induced apoptotic cell death mediated by activation of mitochondrial apoptosis-inducing factor (AIF) suggesting that SAPKs are irrelevant to the apoptosis pathway during PEDV infection. In summary, our data demonstrated critical roles of the p38 and JNK1/2 signaling pathways in facilitating successful viral infection during the post-entry steps of the PEDV life cycle.

The p38 mitogen-activated protein kinase cascade modulates T helper type 17 differentiation and functionality in multiple sclerosis.

The p38 mitogen-activated protein kinase cascade is required for the induction of a T helper type 17 (Th17) -mediated autoimmune response, which underlies the development and progression of several autoimmune diseases, such as experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis (MS). However, the contribution of p38 phosphorylation to human Th cell differentiation has not been clarified. Here we demonstrate that the p38 signalling pathway is implicated in the generation of Th17 lymphocytes from human CD4(+) CD27(+) CD45RA(+) naive T cells, both in healthy donors and in patients affected by the relapsing-remitting form of MS. Our data also indicate that p38 activation is essential for interleukin-17 release from central memory lymphocytes and committed Th17 cell clones. Furthermore, CD4(+) T cells isolated from individuals with relapsing-remitting MS display an altered responsiveness of the p38 cascade, resulting in increased p38 phosphorylation upon stimulation. These findings suggest that the p38 signalling pathway, by modulating the Th17 differentiation and response, is involved in the pathogenesis of MS, and open new perspectives for the use of p38 inhibitors in the treatment of Th17-mediated autoimmune diseases.

Graphene substrate for inducing neurite outgrowth

A few recent studies demonstrated that graphene may have cytocompatibility with several cell types. However, when assessing cell behavior on graphene, there has been no precise control over the quality of graphene, number of graphene layers, and substrate surface coverage by graphene. In this study, using well-controlled monolayer graphene film substrates we tested the cytocompatibility of graphene for human neuroblastoma (SH-SY5Y) cell culture. A large-scale monolayer graphene film grown on Cu foils by chemical vapor deposition (CVD) could be successfully transferred onto glass substrates by wet transfer technique. We observed that graphene substrate could induce enhanced neurite outgrowth, both in neurite length and number, compared with control glass substrate. Interestingly, the positive stimulatory effect by graphene was achieved even in the absence of soluble neurogenic factor, retinoic acid (RA). Key genes relevant to cell neurogenesis, e.g., neurofilament light chain (NFL), were also upregulated on graphene. Inhibitor studies suggested that the graphene stimulation of cellular neurogenesis may be achieved through focal adhesion kinase (FAK) and p38 mitogen-activated protein kinase (MAPK) cascades. Our data indicate that graphene may be exploited as a platform for neural regenerative medicine, and the suggested molecular mechanism may provide an insight into the graphene control of neural cells.

Inhibition of p38 mitogen-activated protein kinase activation in the rostral anterior cingulate cortex attenuates pain-related negative emotion in rats.

The emotional components of pain are far less studied than the sensory components. Previous studies have indicated that the rostral anterior cingulate cortex (rACC) is implicated in the affective response to noxious stimuli. Activation of p38 mitogen-activated protein kinase (MAPK) in the spinal cord has been documented to play an important role in diverse kinds of pathological pain states. We used formalin-induced conditioned place aversion (F-CPA) in rats, an animal model believed to reflect the emotional response to pain, to investigate the involvement of p38 MAPK in the rACC after the induction of affective pain. Intraplantar formalin injection produced a significant activation of p38 MAPK, as well as mitogen-activated kinase kinase (MKK) 3 and MKK6, its upstream activators, in the bilateral rACC. p38 MAPK was elevated in both NeuN-positive neurons and Iba1-positive microglia in the rACC, but not GFAP-positive cells. Blocking p38 MAPK activation in the bilateral rACC using its specific inhibitor SB203580 or SB239063 dose-dependently suppressed the formation of F-CPA. Inhibiting p38 MAPK activation did not affect formalin-induced two-phase spontaneous nociceptive response and low intensity electric foot-shock induced CPA. The present study demonstrated that p38 MAPK signaling pathway in the rACC contributes to pain-related negative emotion. Thus, a new pharmacological strategy targeted at the p38 MAPK cascade may be useful in treating pain-related emotional disorders.

Cardioprotective Role of P38 MAPK During Myocardial Infarction Via Parallel Activation of α‐Crystallin B and Nrf2

Myocardial infarction (MI) is defined as cardiac cell death due to prolonged ischemia. Although necrotic cell death was considered to be solely responsible for myocyte death during MI, it was recently revealed that apoptosis also plays its part in this death process. Our laboratory has recently shown that endoplasmic reticulum (ER) stress-induced apoptosis is the predominant route for apoptosis during MI and the conventional mitochondrial pathway is bypassed by activation of a small heat shock protein α-crystallin B (CRYAB). Since CRYAB is a direct target of P38 mitogen-activated protein kinase (MAPK) cascade, we were prompted to check the role of P38 MAPK in 20-week-old male Wister rats immediately after infarct formation. Interestingly, parallel activation of mitochondrial apoptotic pathway with an increase in ER stress-induced apoptotic load was observed along with decreased activation of CRYAB and Nrf2 (a pro-survival protein activated in response to ER stress) in MI rats treated with SB203580, a specific inhibitor of P38α and P38β compared to the MI alone. As a cumulative effect, this inhibitor treatment also resulted in significant increase in the levels of caspase3 activity and TUNEL positivity, the end point apoptotic markers. Furthermore, SB203580-treated hypoxic adult cardiomyocytes showed formation of desmin aggregates which were previously associated with impaired cardiac function. Thus, this study shows for the first time the precise mechanism by which P38 MAPK plays a pro-survival role and confers protection of cardiomyocytes, during infarct formation.