The p38 signal transduction pathway: activation and function

The Impact of obesity and diabetes mellitus on pancreatic cancer: Molecular mechanisms and clinical perspectives

The incidence of obesity and type 2 diabetes (T2DM) in the Western world has increased dramatically during the recent decades. According to the American Cancer Society, pancreatic cancer (PC) is the fourth leading cause of cancer‐related death in the United States. The relationship among obesity, T2DM and PC is complex. Due to increase in obesity, diabetes, alcohol consumption and sedentary lifestyle, the mortality due to PC is expected to rise significantly by year 2040. The underlying mechanisms by which diabetes and obesity contribute to pancreatic tumorigenesis are not well understood. Furthermore, metabolism and microenvironment within the pancreas can also modulate pancreatic carcinogenesis. The risk of PC on a population level may be reduced by modifiable lifestyle risk factors. In this review, the interactions of diabetes and obesity to PC development were summarized, and novel strategies for the prevention and treatment of diabetes and PC were discussed.

Kidney-targeted baicalin-lysozyme conjugate ameliorates renal fibrosis in rats with diabetic nephropathy induced by streptozotocin

BACKGROUND

Diabetic nephropathy (DN) is one of the most common and serious complications of diabetes, and is the most important cause of death for diabetic patients. Baicalin (BAI) has anti-oxidative, anti-inflammatory and anti-apoptotic activities, which play a role in attenuating insulin resistance and protecting the kidney. Moreover, cell-specific targeting of renal tubular cells is an approach to enhance drug accumulation in the kidney.

METHODS

Forty-five Sprague-Dawley rats were divided into four groups. A diabetes model was created using streptozotocin (STZ) intraperitoneally injection. The four groups included: Control group (n = 10), DN (n = 15), BAI treatment (BAI; n = 10) and BAI-LZM treatment (BAI-LZM; n = 10) groups. In the current study, the renoprotection and anti-fibrotic effects of BAI-lysozyme (LZM) conjugate were further investigated in rats with DN induced by STZ compared with BAI treatment alone.

RESULTS

The results suggest that BAI-LZM better ameliorates renal impairment, metabolic disorder and renal fibrosis than BAI alone in rats with DN, and the potential regulatory mechanism likely involves inhibiting inflammation via the nuclear factor-κB signaling pathway, inhibiting extracellular matrix accumulation via the transforming growth factor-β/Smad3 pathway and regulating cell proliferation via the insulin-like growth factor (IGF)-1/IGF-1 receptor/p38 Mitogen-activated protein kinase (MAPK) pathway. BAI and the kidney-targeted BAI-LZM can utilize the body's cytoprotective pathways to reactivate autophagy (as indicated by the autophagy markers mechanistic target of rapamycin and sirtuin 1 to ameliorate DN outcomes.

CONCLUSIONS

Our data support the traditional use of S. baicalensis as an important anti-DN traditional chinese medicine (TCM), and BAI, above all BAI-LZM, is a promising source for the identification of molecules with anti-DN effects.

Overexpression of Toll-Like Receptor 4 Affects Autophagy, Oxidative Stress, and Inflammatory Responses in Monocytes of Transgenic Sheep

Toll-like receptor 4 (TLR4) is a critical pattern recognition receptor that plays a critical role in the host innate immune system’s recognition of Gram-negative bacteria. Since it is the lipopolysaccharide (LPS) receptor, it links the activated inflammatory response with autophagy and oxidative stress. Autophagy, or type II programmed cell death, was reported to have defensive functions in response to the production of inflammatory cytokines and oxidative stress. To explore the relationship between autophagy, inflammation, and oxidative stress, a TLR4-enriched transgenic (Tg) animal model (sheep) was generated. Autophagy activity in the Tg blood monocytes was significantly higher than in the wild-type animal under LPS stress, and it returned to normal after transfection of TLR4 siRNA. Pretreatment with 3-methyladenine (3-MA) inhibited autophagy and enhanced oxidative stress and the production of TNF-α. The LPS-induced reactive oxygen species (ROS) level was markedly increased in the Tg group at an early stage before quickly returning to normal values. In addition, suppressing ROS production by N-acetyl-L-cysteine down-regulated the number of intracellular autophagosomes and the expression of Beclin-1, ATG5, and cytokines IL-1β, IL-6, and TNF-α. Further mechanistic investigation suggested that the TLR4-associated p38 mitogen-activated protein kinase (MAPK) signaling pathway was involved in autophagy and oxidative stress. P38 MAPK promotes intracellular autophagy, ROS production, and inflammatory response. Moreover, TLR4 over-expression suppressed oxidative stress and the production of inflammatory cytokines and increased autophagy activity in vivo. Taken together, our results showed that LPS induced autophagy, which was related to TLR4-mediated ROS production through the p38 MAPK signaling pathway. In addition, our study also provided a novel transgenic animal model to analyze the effects of TLR4 on autophagy, oxidative stress, and inflammatory responses.

Long non-coding RNA growth arrest specific-5: a potential biomarker for early diagnosis of severe asthma

Background

The diagnosis of severe asthma (SA) is difficult due to a necessary long-term treatment history currently, while there are few studies on biomarkers in the diagnosis of SA. Long non-coding RNA (lncRNA) growth arrest specific-5 (GAS5) has the potential of playing this role because its binding with glucocorticoid receptor (GR). The purpose of this article is to explore the possibility of lncRNA GAS5 acting as a biomarker for early diagnosis of severe asthma (SA).

Methods

Peripheral blood was obtained from healthy volunteers, patients with non-severe asthma (nSA) and SA, and peripheral blood mononuclear cells (PBMCs) were separated. Twenty-four female BALB/c mice (aged 6 weeks) were randomly and averagely divided into 3 groups, i.e., control group, asthma group and dexamethasone group. The mice were sensitized and challenged with ovalbumin (OVA) and lipopolysaccharide (LPS) to establish a murine model of steroid-insensitive asthma. Human bronchial epithelial cells (HBECs) were cultured, transfected with miR-9 mimics, JNK1 inhibitor and treated with interleukin (IL)-2 + IL-4 and dexamethasone. Western blot was used to detect glucocorticoid receptor phosphorylation at serine 226 (GR^ser226), and quantitative real-time PCR was used to detect GAS5 level.

Results

The level of GAS5 in PBMCs from nSA group elevated 20-fold higher after dexamethasone treatment in vitro, while it reduced 15-fold lower in SA group (P<0.001). The expression of GR^ser226 in PBMCs from SA group was significantly higher than that from control group and nSA group after dexamethasone treatment (P<0.001). In the lung tissue of mice, the GAS5 level of dexamethasone group was lower than that of asthma group (P<0.001) and control group (P<0.05). Both treatment with IL-2 + IL-4 and transfection of miR-9 mimics could increase the expression of GR^ser226 in HBECs (P<0.001). The GAS5 level in HBECs after IL-2 + IL-4 + Dexamethasone treatment was lower than that in HBECs only treated with IL-2 + IL-4 (P<0.001). Similarly, dexamethasone treatment also decreased the level of GAS5 in HBECs transfected with miR-9 mimics (P<0.05). Moreover, transfecting with JNK1 inhibitor could reverse the expression of GAS5 in HBECs transfected with miR-9 mimics and treated with dexamethasone. However, the level of GAS5 in HBECs interfered with IL-2 + IL-4 + Dexamethasone was not affected by JNK1 inhibitor.

Conclusions

The expression of GAS5 is different in PBMCs between nSA and SA, and is affected by glucocorticoids treatment, which is due to GR^ser226 phosphorylation. GAS5 can be used as a potential biomarker for diagnosis of severe asthma by comparing GAS5 level in PBMCs from patients before and after glucocorticoids treatment in vitro.

A Possible Role of Crustacean Cardioactive Peptide in Regulating Immune Response in Hepatopancreas of Mud Crab

Crustacean cardioactive peptide (CCAP), a cyclic amidated non-apeptide, is widely found in arthropods. The functions of CCAP have been revealed to include regulation of heart rate, intestinal peristalsis, molting, and osmotic pressure. However, to date, there has not been any report on the possible involvement of CCAP in immunoregulation in crustaceans. In this study, a CCAP precursor (designated as Sp-CCAP) was identified in the commercially important mud crab Scylla paramamosain, which could be processed into four CCAP-associated peptides and one mature peptide (PFCNAFTGC-NH₂). Bioinformatics analysis indicated that Sp-CCAP was highly conserved in crustaceans. RT-PCR results revealed that Sp-CCAP was expressed in nerve tissues and gonads, whereas the Sp-CCAP receptor gene (Sp-CCAPR) was expressed in 12 tissues of S. paramamosain, including hepatopancreas. In situ hybridization further showed that an Sp-CCAPR-positive signal is mainly localized in the F-cells of hepatopancreas. Moreover, the mRNA expression level of Sp-CCAPR in the hepatopancreas was significantly up-regulated after lipopolysaccharide (LPS) or polyriboinosinic polyribocytidylic acid [Poly (I:C)] challenge. Meanwhile, the mRNA expression level of Sp-CCAPR, nuclear transcription factor NF-κB homologs (Sp-Dorsal and Sp-Relish), member of mitogen-activated protein kinase (MAPK) signaling pathway (Sp-P38), pro-inflammatory cytokines factor (Sp-TNFSF and Sp-IL16), and antimicrobial peptide (Sp-Lysozyme, Sp-ALF, Sp-ALF4, and Sp-ALF5) in the hepatopancreas were all up-regulated after the administration of synthetic Sp-CCAP mature peptide both in vivo and in vitro. The addition of synthetic Sp-CCAP mature peptide in vitro also led to an increase in nitric oxide (NO) concentration and an improved bacterial clearance ability in the hepatopancreas culture medium. The present study suggested that Sp-CCAP signaling system might be involved in the immune responses of S. paramamosain by activating immune molecules on the hepatopancreas. Collectively, our findings shed new light on neuroendocrine-immune regulatory system in arthropods and could potentially provide a new strategy for disease prevention and control for mud crab aquaculture.

The coordinate actions of calcineurin and Hog1 mediate the stress response through multiple nodes of the cell cycle network

Upon exposure to environmental stressors, cells transiently arrest the cell cycle while they adapt and restore homeostasis. A challenge for all cells is to distinguish between stress signals and coordinate the appropriate adaptive response with cell cycle arrest. Here we investigate the role of the phosphatase calcineurin (CN) in the stress response and demonstrate that CN activates the Hog1/p38 pathway in both yeast and human cells. In yeast, the MAPK Hog1 is transiently activated in response to several well-studied osmostressors. We show that when a stressor simultaneously activates CN and Hog1, CN disrupts Hog1-stimulated negative feedback to prolong Hog1 activation and the period of cell cycle arrest. Regulation of Hog1 by CN also contributes to inactivation of multiple cell cycle-regulatory transcription factors (TFs) and the decreased expression of cell cycle-regulated genes. CN-dependent downregulation of G1/S genes is dependent upon Hog1 activation, whereas CN inactivates G2/M TFs through a combination of Hog1-dependent and -independent mechanisms. These findings demonstrate that CN and Hog1 act in a coordinated manner to inhibit multiple nodes of the cell cycle-regulatory network. Our results suggest that crosstalk between CN and stress-activated MAPKs helps cells tailor their adaptive responses to specific stressors.

In order to survive exposure to environmental stress, cells transiently arrest the cell division cycle while they adapt to the stress. Several kinases and phosphatases are known to control stress adaptation programs, but the extent to which these signaling pathways work together to tune the stress response is not well understood. This study investigates the role of the phosphatase calcineurin in the stress response and shows that calcineurin inhibits the cell cycle in part by stimulating the activity of the Hog1/p-38 stress-activated MAPK in both yeast and human cells. Crosstalk between stress response pathways may help cells mount specific responses to diverse stressors and to survive changes in their environment.

Identification of Age-Specific and Common Key Regulatory Mechanisms Governing Eggshell Strength in Chicken Using Random Forests

In today's chicken egg industry, maintaining the strength of eggshells in longer laying cycles is pivotal for improving the persistency of egg laying. Eggshell development and mineralization underlie a complex regulatory interplay of various proteins and signaling cascades involving multiple organ systems. Understanding the regulatory mechanisms influencing this dynamic trait over time is imperative, yet scarce. To investigate the temporal changes in the signaling cascades, we considered eggshell strength at two different time points during the egg production cycle and studied the genotype-phenotype associations by employing the Random Forests algorithm on chicken genotypic data. For the analysis of corresponding genes, we adopted a well established systems biology approach to delineate gene regulatory pathways and master regulators underlying this important trait. Our results indicate that, while some of the master regulators (Slc22a1 and Sox11) and pathways are common at different laying stages of chicken, others (e.g., Scn11a, St8sia2, or the TGF- β pathway) represent age-specific functions. Overall, our results provide: (i) significant insights into age-specific and common molecular mechanisms underlying the regulation of eggshell strength; and (ii) new breeding targets to improve the eggshell quality during the later stages of the chicken production cycle.

ASK1 Mediates Nur77 Expression in T-Cell Receptor Mediated Thymocyte Apoptosis

: Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that activates downstream JNK and p38 mitogen-activated protein kinase (MAPK) to relay death signals into cells in response to various environmental stress. However, whether ASK1 plays a role in T cell receptor (TCR)-mediated apoptosis of thymocytes is unclear. Here, we show that ASK1 is activated upon TCR stimulation and plays an important role in TCR-mediated apoptosis of thymocytes by triggering downstream JNK and p38 signaling cascades. Mechanistically, ASK1-JNK/p38 signaling leads to the upregulation of neuron-derived clone 77 (Nur77), a critical pro-apoptotic protein involved in TCR-mediated apoptosis of thymocytes. Furthermore, we demonstrate that the activation of ASK1 is negatively modulated by Akt upon TCR stimulation. Thus, our results identify a previously unappreciated signaling mechanism involving ASK1 in TCR-mediated apoptosis of thymocytes.

Molecular Characterization and Expression of OfJNK and Ofp38 in Ostrinia furnacalis (Guenée) Under Different Environmental Stressors

Ostrinia furnacalis, an important pest of corn, has substantial detrimental effects on corn production. The mitogen-activated protein kinase (MAPK) signaling pathway plays a pivotal role in an insect’s resistance to environmental stress. The expression levels of JNK and p38 have been well recorded in several insects under different environmental stressors, at different developmental stages, and in various tissue types; however, there is limited information on JNK and p38 in agricultural insects. To clarify the mechanism whereby O. furnacalis responds to environmental stress, we cloned JNK and p38 from O. furnacalis and subsequently named them OfJNK and Ofp38, respectively. Further, we examined the expression levels of OfJNK and Ofp38 under different environmental stressors. In this study, we obtained full-length sequences of OfJNK and Ofp38, and RT-qPCR results showed that these genes were expressed at all developmental stages, in various tissues (head, chest, abdomen, leg, wing, antennae, compound eye, midgut, and ovary) and under different environmental stressors (4°C and ultraviolet A treatment for 0, 30, 60, 90, and 120 min). The expression levels of OfJNK and Ofp38 were relatively higher in eggs and 3-day-old adult females than in other developmental stages. Moreover, the expression level of OfJNK was higher in the wings than in other tissues, whereas that of Ofp38 was significantly higher in the ovaries than in other tissues. OfJNK and Ofp38 showed high expression 90 min after being subjected to treatment at 4°C and ultraviolet A irradiation; the expression of Ofp38 peaked at 30 min, whereas that of OfJNK peaked at 60 min. These results indicate that O. furnacalis differs in terms of its response under different environmental stressors. In summary, our results will provide a foundation for additional research needed to determine the role of the MAPK signaling pathway and the underlying mechanisms by which it shows resistance to environmental stresses in insects.

A stress response p38 MAP kinase inhibitor SB202190 promoted TFEB/TFE3-dependent autophagy and lysosomal biogenesis independent of p38

TFEB (transcription factor EB) and TFE3 (transcription factor E3) are “master regulators” of autophagy and lysosomal biogenesis. The stress response p38 mitogen-activated protein (MAP) kinases affect multiple intracellular responses including inflammation, cell growth, differentiation, cell death, senescence, tumorigenesis, and autophagy. Small molecule p38 MAP kinase inhibitors such as SB202190 are widely used in dissection of related signal transduction mechanisms including redox biology and autophagy. Here, we initially aimed to investigate the links between p38 MAP kinase and TFEB/TFE3-mediated autophagy and lysosomal biogenesis. Unexpectedly, we found that only SB202190, rather than several other p38 inhibitors, promotes TFEB and TFE3 to translocate from the cytosol into the nucleus and subsequently enhances autophagy and lysosomal biogenesis. In addition, siRNA-mediated Tfeb and Tfe3 knockdown effectively attenuated SB202190-induced gene expression and lysosomal biogenesis. Mechanistical studies showed that TFEB and TFE3 activation in response to SB202190 is dependent on PPP3/calcineurin rather than on the inhibition of p38 or MTOR signaling, the main pathway for regulating TFEB and TFE3 activation. Importantly, SB202190 increased intracellular calcium levels, and calcium chelator BAPTAP-AM blocked SB202190-induced TFEB and TFE3 activation as well as autophagy and lysosomal biogenesis. Moreover, endoplasmic reticulum (ER) calcium is required for TFEB and TFE3 activation in response to SB202190. In summary, we identified a previously uncharacterized role of SB202190 in activating TFEB- and TFE3-dependent autophagy and lysosomal biogenesis via ER calcium release and subsequent calcium-dependent PPP3/calcineurin activation, leading to dephosphorylation of TFEB and TFE3. Given the importance of p38 MAP kinase invarious conditions including oxidative stress, the findings collectively indicate that SB202190 should not be used as a specific inhibitor for elucidating the p38 MAP kinase biological functions due to its potential effect on activating autophagy-lysosomal axis.

•

A stress response p38 MAP kinase inhibitor SB202190 promoted TFEB/TFE3-dependent autophagy and lysosomal biogenesis.

•

SB202190-induced TFEB/TFE3 activation is independent of p38 MAP kinase inhibition.

•

SB202190-induced TFEB/TFE3 activation is independent of mTOR inhibition.

•

ER calcium-induced PPP3/calcineurin is required for TFEB/TFE3 activation in response to SB202190.

Inhibitory Activity of a Scorpion Defensin BmKDfsin3 against Hepatitis C Virus

Hepatitis C virus (HCV) infection is a major worldwide health problem which can cause chronic hepatitis, liver fibrosis and hepatocellular carcinoma (HCC). There is still no vaccine to prevent HCV infection. Currently, the clinical treatment of HCV infection mainly relies on the use of direct-acting antivirals (DAAs) which are expensive and have side effects. Here, BmKDfsin3, a scorpion defensin from the venom of Mesobuthus martensii Karsch, is found to dose-dependently inhibit HCV infection at noncytotoxic concentrations and affect viral attachment and post-entry in HCV life cycle. Further experimental results show that BmKDfsin3 not only suppresses p38 mitogen-activated protein kinase (MAPK) activation of HCV-infected Huh7.5.1 cells, but also inhibits p38 activation of Huh7.5.1 cells stimulated by tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) or lipopolysaccharide (LPS). BmKDfsin3 is also revealed to enter into cells. Using an upstream MyD88 dimerization inhibitor ST2345 or kinase IRAK-1/4 inhibitor I, the inhibition of p38 activation represses HCV replication in vitro. Taken together, a scorpion defensin BmKDfsin3 inhibits HCV replication, related to regulated p38 MAPK activation.

MAP kinase phosphatase-1, a gatekeeper of the acute innate immune response

Mitogen-activated protein kinase (MAPK)^§ cascades are crucial signaling pathways in the regulation of the host immune response to infection. MAPK phosphatase (MKP)-1, an archetypal member of the MKP family, plays a pivotal role in the down-regulation of p38 and JNK. Studies using cultured macrophages have demonstrated a pivotal role of MKP-1 in the restraint of the biosynthesis of both pro-inflammatory and anti-inflammatory cytokines as well as chemokines. Using MKP-1 knockout mice, several groups have not only confirmed the critical importance of MKP-1 in the regulation of the cytokine synthesis in vivo during the acute host response to bacterial infections, but also revealed novel functions of MKP-1 in maintaining bactericidal functions and host metabolic activities. RNA-seq analyses on livers of septic mice infected with E. coli have revealed that MKP-1 deficiency caused substantial perturbation in the expression of over 5000 genes, an impressive >20% of the entire murine genome. Among the genes whose expression are dramatically affected by MKP-1 deficiency are those encoding metabolic regulators and acute phase response proteins. These studies demonstrate that MKP-1 is an essential gate-keeper of the acute innate immune response, facilitating pathogen killing and regulating the metabolic response during pathogenic infection. In this review article, we will summarize the studies on the function of MKP-1 during acute innate immune response in the regulation of inflammation, metabolism, and acute phase response. We will also discuss the role of MKP-1 in the actions of numerous immunomodulatory agents.

Up-regulated fibronectin in 3D culture facilitates spreading of triple negative breast cancer cells on 2D through integrin β-5 and Src

Using MDA-MB-231 cells as a model of triple negative breast cancer (TNBC) and its metastatic sub-cell lines that preferentially metastasize to lung, bone or brain, we found that the mRNA and protein levels of fibronectin (FN) are increased in MDA-MB-231 cells and its lung metastatic derivative, when cultivated in three-dimensional (3D) suspension cultures. The increase of FN expression in 3D was dependent on p38 mitogen-activated protein kinase (MAPK) because it was prevented by treatment of cells with SB203580, an inhibitor of p38MAPK. The up-regulated FN was converted into fibrils, and it enhanced cell spreading when cells cultured in 3D were transferred to two-dimensional (2D) culture. The arginine-glycine-aspartate (RGD) peptides and siRNAs targeting of integrin β-5 inhibited spreading of cells regardless of the presence of FN on 2D culture dishes. In addition, the levels of phosphorylated Src were found to be increased in 3D and the treatment of cells with SU6656, an inhibitor of Src, decreased the rate of cell spreading on FN. Collectively, these studies demonstrate that increased cellular FN in 3D suspension culture facilitates cancer cell attachment and spreading via integrin β-5 and Src, suggesting that the increased FN promotes initial attachment of cancer cells to secondary organs after circulation during metastasis.

Retinoic acid inducible gene-I slows down cellular senescence through negatively regulating the integrin β3/p38 MAPK pathway

Retinoic acid inducible gene-I (Rig-I) has been well documented as a cytosolic pattern recognition receptor that can sense viral RNA ligands to initiate the interferon-mediated antiviral immunity. However, little is known about the biological behaviors of Rig-I devoid of viral infection. Herein, we investigated the roles of Rig-I in the regulation of cellular senescence. In comparison to wild-type counterparts, Rig-I-/- mice displayed the accelerated loss of hair, less responsiveness to gentle physical stimuli and shorten survival time. Likewise, Rig-I deficiency rendered mouse embryonic fibroblasts (MEFs) more susceptible to the serial passages-associated replicative senescence. By performing a transcriptome analysis, we identified integrins at the intersections of biological pathways affected by Rig-I. Among these, integrin β3 was negatively regulated by Rig-I, and significantly upregulated with the occurrence of senescence. Gene silencing of Itgb3 (encoding integrin β3) retarded the progression of cellular senescence in both WT and Rig-I-/- MEFs. Notably, this effect was more prominent in Rig-I-/- MEFs. Furthermore, p38 MAPK was a key downstream molecule for integrin β3-mediated senescence, and overactivated in senescent Rig-I-/- MEFs. Taken together, Rig-I deficiency contributes to cellular senescence through amplifying integrin β3/p38 MAPK signaling. Our findings provide the evidence that Rig-I is a key regulator of cellular senescence, which will be helpful in better understanding its function without viral infection.Abbreviations: Rig-I: retinoic acid inducible gene-I; SASP: senescence-associated secretory phenotype; ECM: extracellular matrix; Itgb3: integrin beta 3; PRR: pattern recognition receptor; MEFs: mouse embryonic fibroblasts; Il-1β: interleukin-1 beta; Il-6: interleukin-6; Il-8: interleukin-8; Cxcl1: chemokine (C-X-C motif) ligand 1; Ccl2: chemokine (C-C motif) ligand 2; WT, wild type; BM: bone marrow; MAPK: mitogen-activated protein kinase; ERK: extracellular signal-regulated kinases; JNK: Jun N-terminal kinases; SA-β-gal: senescence-associated β-galactosidase; qPCR: quantitative reverse-transcription PCR; PBS: phosphate-buffered saline.

p38 MAPK is involved in the immune response to pathogenic Vibrio in the clam Meretrix petechialis

p38 mitogen-activated protein kinases (MAPKs) are involved in the response to various extracellular stimuli via regulating gene expression. In the present study, a p38 MAPK gene (MpP38) was identified from the clam Meretrix petechialis. The full-length cDNA of MpP38 measures 1,720 bp, consisting of a 134-bp 5'-UTR, a 1,095-bp ORF and a 491-bp 3'-UTR. Both the mRNA and protein expression levels of MpP38 increased after Vibrio challenge, implying that MpP38 is involved in clam immunity. Based on our previous study, a transcription factor activated by p38 MAPK, i.e. microphthalmia-associated transcription factor (MITF), participated in clam immunity by regulating the expression of phenoloxidase (PO). Coupled with other related reports, the mechanism underlying the involvement of MpP38 in clam immunity is most likely that pathogen stimuli induce the phosphorylation of p38 MAPK and thus activate MITF to regulate the expression of the immune-related gene PO. The results obtained in this study support this mechanism. First, we found that the MpP38 phosphorylation level increased in response to Vibrio challenge. Second, as revealed by a yeast two-hybrid assay, there was a direct interaction between MpP38 and MITF. Meanwhile, inhibiting the phosphorylation of MpP38 decreased the phosphorylation level of MpMITF, implying that MpP38 phosphorylation is required for MpMITF activation. Additionally, our results showed that there was a regulatory relationship between MpP38 phosphorylation level and PO expression level. With increased MpP38 phosphorylation level, the PO expression level was also increased after Vibrio challenge; when MpP38 phosphorylation was inhibited, the PO expression level was significantly decreased. This study describes the immune function of p38 MAPK in the clam for the first time and analyses its potential underlying mechanism, which will help to elucidate the immune mechanism in the clam M. petechialis.

Macrophages-derived p38α promotes the experimental severe acute pancreatitis by regulating inflammation and autophagy

BACKGROUND

Severe acute pancreatitis (SAP) is a common threat to human health. In the present study, we aimed to investigate the underlying mechanisms by which p38α in macrophages contributes to SAP. We used conditional knockout of p38α in macrophages and p38 MAPK inhibitors to understand the effects of p38α in macrophages on caerulein-induced inflammatory responses in SAP mice models.

METHODS AND MATERIALS

Wild-type (WT) mice were randomly divided into three groups: a control group, SAP group, and SAP + p38MAPK inhibitor (SB203580) group, and mice with a conditional knockout (KO) of p38α in macrophages were included in a KO + SAP group. We evaluated pancreatic pathology and ultra-structure by hematoxylin and eosin staining and transmission electron microscopy. The pulmonary wet-to-dry weight ratio was calculated. The serum levels of TNF-α and IL-1β were determined by ELISA. The mRNA and protein expression of inflammatory cytokines TNF-α, IL-1β, IL-17, IL-18, MIF, and MCP-1 in pancreatic tissues were tested by qRT-PCR and immunohistochemistry analysis. The protein expression of p38, caspase-1, ULK1, LC3B and p62 in pancreatic tissues was examined by Western blotting.

RESULTS

The results indicated that the severity of SAP as well as the expression of the cytokines TNF-α, IL-1β, IL-17, IL-18 and MCP-1 were higher in the SAP group than those in the control group, but were lower in the SAP + SB203580 and KO + SAP groups as compared with the SAP group. The protein expression of p38, caspase-1, LC3B and p62 was increased in the SAP group than that in the control group, but this result was reversed in the SAP + SB203580 and KO + SAP groups as compared with the SAP group. In addition, the ULK1 level was significantly lower in the SAP group than that in the control group, but was increased in the SAP + SB203580 and KO + SAP groups as compared with the SAP group.

CONCLUSIONS

Our findings demonstrated that, macrophage derived p38α promoted the experimental severe acute pancreatitis by regulating inflammation and autophagy.

MKK7, the essential regulator of JNK signaling involved in cancer cell survival: a newly emerging anticancer therapeutic target

One of the mitogen-activated protein kinases (MAPKs), c-Jun NH2-terminal protein kinase (JNK) plays an important role in regulating cell fate, such as proliferation, differentiation, development, transformation, and apoptosis. Its activity is induced through the interaction of MAPK kinase kinases (MAP3Ks), MAPK kinases (MAP2Ks), and various scaffolding proteins. Because of the importance of the JNK cascade to intracellular bioactivity, many studies have been conducted to reveal its precise intracellular functions and mechanisms, but its regulatory mechanisms remain elusive. In this review, we discuss the molecular characterization, activation process, and physiological functions of mitogen-activated protein kinase kinase 7 (MKK7), the MAP2K that most specifically controls the activity of JNK. Understanding the role of MKK7/JNK signaling in physiological conditions could spark new hypotheses for targeted anticancer therapies.

Sea Urchin Extracellular Proteins Design a Complex Protein Corona on Titanium Dioxide Nanoparticle Surface Influencing Immune Cell Behavior

Extensive exploitation of titanium dioxide nanoparticles (TiO₂NPs) augments rapid release into the marine environment. When in contact with the body fluids of marine invertebrates, TiO₂NPs undergo a transformation and adhere various organic molecules that shape a complex protein corona prior to contacting cells and tissues. To elucidate the potential extracellular signals that may be involved in the particle recognition by immune cells of the sea urchin Paracentrotus lividus, we investigated the behavior of TiO₂NPs in contact with extracellular proteins in vitro. Our findings indicate that TiO₂NPs are able to interact with sea urchin proteins in both cell-free and cell-conditioned media. The two-dimensional proteome analysis of the protein corona bound to TiO₂NP revealed that negatively charged proteins bound preferentially to the particles. The main constituents shaping the sea urchin cell-conditioned TiO₂NP protein corona were proteins involved in cellular adhesion (Pl-toposome, Pl-galectin-8, Pl-nectin) and cytoskeletal organization (actin and tubulin). Immune cells (phagocytes) aggregated TiO₂NPs on the outer cell surface and within well-organized vesicles without eliciting harmful effects on the biological activities of the cells. Cells showed an active metabolism, no oxidative stress or caspase activation. These results provide a new level of understanding of the extracellular proteins involved in the immune-TiO₂NP recognition and interaction in vitro, confirming that primary immune cell cultures from P. lividus can be an optional model for swift and efficient immune-toxicological investigations.

N‑acetyl cysteine inhibits lipopolysaccharide‑induced apoptosis of human umbilical vein endothelial cells via the p38MAPK signaling pathway

Lipopolysaccharide (LPS) can regulate the expression of apoptotic factors, including caspase‑3, Bcl‑2 and Bcl‑2‑associated X protein (Bax). Nitric oxide (NO) plays an important role in apoptosis. N‑acetyl cysteine (NAC) has been shown to exhibit antioxidant effects in vitro. However, the effects of NAC on LPS‑induced apoptosis of human umbilical vein endothelial cells (HUVECs) and the associated mechanisms are not well characterized. The present study explored the effect of NAC on LPS‑induced apoptosis of HUVECs and determined the participation of the p38 mitogen‑activated protein kinase (MAPK) pathway in the process of apoptosis. Cell viability was assessed using the Cell Counting Kit‑8 (CCK‑8) assay. The expression of caspase‑3, Bax, Bcl‑2, phosphorylated (p)‑p38MAPK/total (t‑)p38MAPK and p‑endothelial e nitric oxide synthase (eNOS)/t‑eNOS proteins were determined by western blotting. The expression levels of caspase‑3, Bax and Bcl‑2 mRNA were determined using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The rate of apoptosis was determined using flow cytometry. An NO detection kit (nitric reductase method) was used to determine NO concentration. The results of CCK‑8 and flow cytometric analyses showed that pretreatment of HUVECs with NAC or p38MAPK inhibitor (SB203580) attenuated LPS‑induced decrease in cell viability and increase in cell apoptosis. RT‑qPCR and western blotting showed that LPS promoted caspase‑3 and Bax expression, but inhibited that of Bcl‑2 in HUVECs; however, these effects were attenuated by pretreatment with NAC or SB203580. LPS stimulation significantly enhanced the expression of p‑p38MAPK protein and reduced the expression of p‑eNOS protein; however, these effects were attenuated by pretreatment with NAC or SB203580. NAC pretreatment attenuated LPS‑induced inhibition of NO synthesis, which was consistent with the effects of SB203580. The results demonstrated that NAC pretreatment alleviated LPS‑induced apoptosis and inhibition of NO production in HUVECs. Furthermore, these effects were proposed to be mediated via the p38MAPK signaling pathway.

Mutual Stabilization between TRIM9 Short Isoform and MKK6 Potentiates p38 Signaling to Synergistically Suppress Glioblastoma Progression

p38 signaling is broadly involved in controlling inflammation and stress-induced cell death; however, the mechanisms controlling its activity have seldom been studied. Here, we report that TRIM9 short isoform (TRIM9s) potentiates p38 signaling by stabilizing MKK6. Mechanistic studies revealed that TRIM9s promotes the K63-linked ubiquitination of MKK6 at Lys82, thus inhibiting the degradative K48-linked ubiquitination of MKK6 at the same lysine. MKK6 could also stabilize TRIM9s by promoting the phosphorylation of TRIM9s at Ser76/80 via p38, thereby blocking the ubiquitin-proteasome pathway. Further functional analyses showed that p38 signaling plays a critical role in suppressing glioblastoma progression. Co-reduction of MKK6 and TRIM9s is significantly associated with overall poor survival of glioblastoma patients. We identify a positive feedback loop in p38 signaling generated by MKK6-TRIM9s, which suppresses glioblastoma progression, and we provide insights into the mechanisms by which TRIM9s and MKK6 potentiate p38 signaling through mutual stabilization.

Co-administration of resveratrol with doxorubicin in young mice attenuates detrimental late-occurring cardiovascular changes

Aims

Doxorubicin (DOX) is among the most effective chemotherapies used in paediatric cancer patients. However, the clinical utility of DOX is offset by its well-known cardiotoxicity, which often does not appear until later in life. Since hypertension significantly increases the risk of late-onset heart failure in childhood cancer survivors, we investigated whether juvenile DOX exposure impairs the ability to adapt to angiotensin II (Ang II)-induced hypertension later in life and tested a treatment that could prevent this.

Methods and results

Five-week-old male mice were administered a low dose of DOX (4 mg/kg) or saline once a week for 3 weeks and then allowed to recover for 5 weeks. Following the 5-week recovery period, mice were infused with Ang II or saline for 2 weeks. In another cohort, mice were fed chow containing 0.4% resveratrol 1 week before, during, and 1 week after the DOX administrations. One week after the last DOX administration, p38 mitogen-activated protein kinase (MAPK) was activated in hearts of DOX-treated mice demonstrating molecular signs of cardiac stress; yet, there was no change in cardiac function between groups. However, DOX-treated mice failed to develop compensatory cardiac hypertrophy in response to Ang II-induced hypertension later in life. Of importance, mice receiving DOX with resveratrol co-administration displayed normalization in p38 MAPK activation in the heart and a restored capacity for cardiac hypertrophy in response to Ang II-induced hypertension.

Conclusion

We have developed a juvenile mouse model of DOX-induced cardiotoxicity that displays no immediate overt physiological dysfunction; but, leads to an impaired ability of the heart to adapt to hypertension later in life. We also show that co-administration of resveratrol during DOX treatment was sufficient to normalize molecular markers of cardiotoxicity and restore the ability of the heart to undergo adaptive remodelling in response to hypertension later in life.

Effect of M2 Macrophages on Injury and Apoptosis of Renal Tubular Epithelial Cells Induced by Calcium Oxalate Crystals

Background: M2 macrophages have important roles in diseases such as tumours, cardiovascular diseases and renal diseases. This study aimed to determine the effects and protective mechanism of M2 macrophages against oxidative stress injury and apoptosis induced by calcium oxalate crystals (CaOx) in renal tubular epithelial cells (HK-2) under coculture conditions. Methods: THP-1 cells were induced to differentiate into M2 macrophages by using phorbol-12-myristate-13-acetate, IL-4 and IL-13. Morphological features were observed by microscopy. Phenotypic markers were identified by reverse transcription-polymerase chain reaction, Western blot and enzyme-linked immunosorbent assay (ELISA). HK-2 cells were treated with 0.5 mg/mL CaOx crystals and co-cultured with M2 macrophages or apocynin. The viability of HK-2 cells was detected by CCK-8 assay. The lactate dehydrogenase (LDH) activity of HK-2 cells was analysed using a microplate reader. The apoptosis of HK-2 cells was examined by flow cytometry and Hoechst 33258 staining. Reactive oxygen species (ROS) expression and mitochondrial membrane potential in HK-2 cells were detected by a fluorescence microplate reader. Western blot analysis was conducted to detect the expression of p47phox, Bcl-2, cleaved caspase-3, cytochrome c, p38 MAPK, phospho-p38 MAPK, Akt and phospho-Akt. Results: The results of morphology, reverse transcription-polymerase chain reaction, Western blot and ELISA showed that THP-1 cells were successfully polarised to M2 macrophages. The results of co-culture suggested that M2 macrophages or apocynin significantly increased the cell viability and decreased the LDH activity and apoptosis rate after HK-2 cells were challenged with CaOx crystals. The expression of the p47phox protein and the concentration of ROS were reduced, the release of mitochondrial membrane potential and the expression of the Bcl-2 protein were upregulated and the protein expression of cleaved caspase-3 and cytochrome c was downregulated. The expression of the phosphorylated form of p38 MAPK increased. Under coculture conditions with M2 macrophages, the Akt protein of HK-2 cells treated with CaOx crystals was dephosphorylated, but the phosphorylated form of Akt was not reduced by apocynin. Conclusions: M2 macrophages reduced the oxidative stress injury and apoptosis of HK-2 cells by downregulating the activation of NADPH oxidase, reducing the production of ROS, inhibiting the phosphorylation of p38 MAPK and enhancing the phosphorylation of Akt. We have revealed one of the possible mechanisms by which M2 macrophages reduce the formation of kidney stones.

New Insights into the Process of Placentation and the Role of Oxidative Uterine Microenvironment

For a successful pregnancy to occur, a predecidualized receptive endometrium must be invaded by placental differentiated cells (extravillous trophoblast cells (EVTs)) and, at the same time, continue decidualization. EVT invasion is aimed at anchoring the placenta to the maternal uterus and ensuring local blood supply increase necessary to provide normal placental and foetal development. The first is achieved by migrating through the maternal endometrium and deeper into the myometrium, while the second by transforming uterine spiral arteries into large vessels. This process is a tightly regulated battle comprising interests of both the mother and the foetus. Invading EVTs are required to perform a scope of functions: move, adhere, proliferate, differentiate, interact, and digest the extracellular matrix (ECM); tolerate hypoxia; transform the maternal spiral arteries; and die by apoptosis. All these functions are modulated by their surrounding microenvironment: oxygen, soluble factors (e.g., cytokines, growth factors, and hormones), ECM proteins, and reactive oxygen species. A deeper comprehension of oxidative uterine microenvironment contribution to trophoblast function will be addressed in this review.

P38 MAPK signaling pathway mediates COM crystal-induced crystal adhesion change in rat renal tubular epithelial cells

The objective of the study is to clarify the mechanism of p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway in the change of crystal adhesion in rat renal tubular epithelial cells (NRK-52E) induced by calcium oxalate monohydrate (COM) crystals. NRK-52E cells were divided into COM crystal-treated group and control group according to whether the cell culture medium contains different concentrations of COM crystals. The concentrations of lactate dehydrogenase in the both group medium were determined after being cultured for 24 h. Protein and RNA were extracted from both cell groups after being cultured at different time points. SB239063, an inhibitor of the activation of p38 MAPK, was pretreated for 2 h before incubation with COM crystals. Western blotting and RT-qPCR were performed to confirm the expression levels of relative genes. All the experimental results were summarized and analyzed by SPSS 20.0 statistical analysis software. COM crystals (146 µg/cm²) could induce the expression levels of NLRP3, caspase-1 and interleukin-1β (IL-1β) significantly increased in NRK-52E cells. Compared with the control group cells, the transcription and translation levels of p38 MAPK-related molecule (such as p-p38) and adhesion molecules (such as osteopontin, hyaluronic acid and CD44) were significantly increased in COM crystal-treated cells and can be inhibited by SB239063 and NLRP3 gene silencing. This study demonstrated that the p38 MAPK signaling pathway mediated the COM crystal-induced crystal adhesion change in NRK-52E cells and required the involvement of NLRP3 inflammasome.

Sea cucumber extract TBL-12 inhibits the proliferation, migration, and invasion of human prostate cancer cells through the p38 mitogen-activated protein kinase and intrinsic caspase apoptosis pathway

BACKGROUND

Sea cucumber is a kind of nutritious echinoderm that has multiple biological activities, including antioxidant, antibacterial, and antitumor activities. However, there is no extensive study on the antitumor effect of sea cucumber extract on prostate cancer (PCa). TBL-12 is a new sea cucumber extract. In this study, we investigated the in vivo anti-PCa effect of TBL-12 and its in vitro effects on the proliferation, apoptosis, migration, and invasion of the human PCa cell lines LNCaP, 22RV1, PC-3, and DU145, and evaluated its possible mechanisms.

METHODS

Cell proliferation was analyzed by cell counting kit-8 and colony formation assays. Scratch migration assay and transwell invasiveness assay were used to observe TBL-12 effect on the migration and invasion of PCa cells. Matrix metalloproteinase 2 (MMP-2) and MMP-9 expression and enzymatic activity was determined by Western blot analysis, quantitative reverse-transcription polymerase chain reaction, and gelatin zymography. Apoptosis level was detected by flow cytometry analysis. Western blot analysis was used to analyze p38 mitogen-activated protein kinase (MAPK) and apoptosis pathways. Angiogenic array analysis was used to explore autocrine and paracrine growth factors in PCa cell lines. Xenograft tumor model was built to observe the in vivo anticancer effect.

RESULTS

TBL-12 could significantly inhibit tumor growth in xenograft PCa mice in vivo, and dramatically inhibit the proliferation, colony formation, migration, and invasiveness of PCa cells in vitro (P < 0.05 and P < 0.001). The expression and enzyme activity of MMP-2 and MMP-9 were significantly suppressed by TBL-12 ( P < 0.01), and decreased phosphorylation level of p38 in PCa cells was detected ( P < 0.001). Furthermore, TBL-12 could reinforce the MMP-2/MMP-9 inhibitory effect of SB203580, a specific inhibitor of the p38 MAPK pathway ( P < 0.05). Besides, TBL-12 could induce the apoptosis of PCa cells by activating caspase-9, caspase-7, and poly(ADP-ribose) polymerase and suppressing survivin, and inhibit the secretion of angiogenin, angiopoietin-2, and vascular endothelial growth factor in PCa cells.

CONCLUSIONS

Sea cucumber extract TBL-12 could suppress the proliferation and metastasis of human PCa cells by inhibiting MMP-2 and MMP-9 via blocking the p38 MAPK pathway, inducing apoptosis through intrinsic caspase apoptosis pathway and inhibiting the secretion of angiogenic factors. Our findings may be of importance and significance for the research and clinical applications of sea cucumber extract in PCa treatment.

Potential role of P2X7 receptor in neurodegenerative processes in a murine model of glaucoma

Glaucoma is a common cause of visual impairment and blindness, characterized by retinal ganglion cell (RGC) death. The mechanisms that trigger the development of glaucoma remain unknown and have gained significant relevance in the study of this neurodegenerative disease. P2X7 purinergic receptors (P2X7R) could be involved in the regulation of the synaptic transmission and neuronal death in the retina through different pathways. The aim of this study was to characterize the molecular signals underlying glaucomatous retinal injury. The time-course of functional, morphological, and molecular changes in the glaucomatous retina of the DBA/2J mice were investigated. The expression and localization of P2X7R was analysed in relation with retinal markers. Caspase-3, JNK, and p38 were evaluated in control and glaucomatous mice by immunohistochemical and western-blot analysis. Furthermore, electroretinogram recordings (ERG) were performed to assess inner retina dysfunction. Glaucomatous mice exhibited changes in P2X7R expression as long as the pathology progressed. There was P2X7R overexpression in RGCs, the primary injured neurons, which correlated with the loss of function through ERG measurements. All analyzed MAPK and caspase-3 proteins were upregulated in the DBA/2J retinas suggesting a pro-apoptotic cell death. The increase in P2X7Rs presence may contribute, together with other factors, to the changes in retinal functionality and the concomitant death of RGCs. These findings provide evidence of possible intracellular pathways responsible for apoptosis regulation during glaucomatous degeneration.

CUEDC2 Contributes to Cisplatin-Based Chemotherapy Resistance in Ovarian Serious Carcinoma by Regulating p38 MAPK Signaling

Chemoresistance remains an obstacle to the successful treatment of ovarian carcinoma. CUE domain-containing 2 (CUEDC2) plays critical roles in tumor genesis and overexpresses in many solid cancers, including ovarian serous carcinoma. In previous study, we found that overexpression of CUEDC2 might be a promising biomarker to evaluate the progression and to predict likely relapse of serous ovarian carcinoma. In present study, we found that higher expression of CUEDC2 was associated with higher resistance to cisplatin. The overall survival (OS) and disease-free survival time (DFS) of patients with cisplatin resistant was shorter than that of those with cisplatin sensitive, respectively, and the cisplatin sensitivity was independent predictor of a shorter OS time and DFS time. Knockdown of CUEDC2 by small interfering RNA enhanced the cisplatin sensitivity of serous ovarian carcinoma cells in SKOV3 cell lines. Furthermore, the phosphorylation of p38 MAPK were obviously increased after CUEDC2 knockdown, while p38 MAPK signaling contributes to cell growth and cell apoptosis. Our data suggest that CUEDC2 takes part in cisplatin-based chemotherapy resistance by regulating p38 MAPK signaling. And CUEDC2 is a promising biomarker and therapeutic target of cisplatin resistance in ovarian serous carcinoma.

Inactivation of Cyclic AMP Response Element Transcription Caused by Constitutive p38 Activation Is Mediated by Hyperphosphorylation-Dependent CRTC2 Nucleocytoplasmic Transport

The p38 signal transduction pathway can be activated transiently or constitutively, depending on the contexts in which the activation occurs. However, the biological consequence of constitutive activation of p38 is largely unknown. After screening 300 transcriptional cofactors, we identified CRTC2 as a downstream substrate of constitutively activated p38. Constitutive, rather than transient, activation of p38 led to hyperphosphorylation of CRTC2, resulting in CRTC2 cytosolic relocation and subsequent inactivation of cyclic AMP response element (CRE)-mediated transcription. Interestingly, the cytosolic translocation of CRTC2 depended on phosphorylation accumulation at multiple sites (≥11 phosphoserine/phosphothreonine residues) but not on specific sites. The hyperphosphorylation-driven nucleocytoplasmic transport of CRTC2 may not be a rare case of nuclear export of proteins, as we also observed that constitutively activated p38 promoted FOS nuclear export in a hyperphosphorylation-dependent manner. Collectively, our study uncovered a previously unknown mechanism of inactivation of selected transcription, which results from hyperphosphorylation-driven nucleocytoplasmic transport of cofactors or transcription factors mediated by constitutively active kinase.

An immunosuppressive peptide from the horsefly inhibits inflammation by repressing macrophage maturation and phagocytosis

Ectoparasites repress host immune responses while they obtain nutrition from their hosts. Understanding the immunosuppressive mechanisms between ectoparasites and their hosts will provide new strategies to develop potential immunosuppressive drugs against immune disorder diseases. Previously, we have discovered that a small peptide, immunoregulin HA, from the horsefly (Hybomitra atriperoides) may play an immunosuppressive role in rat splenocytes. However, the targeting cells and detailed mechanisms of immunoregulin HA in immunosuppressive reactions are not well defined. Here, we show that immunoregulin HA reduces the secretion of proinflammatory cytokines upon lipopolysaccharide (LPS) stimulation. Interestingly, we discover that the major cytokines repressed by immunoregulin HA are secreted by macrophages, rather than by T cells. Furthermore, immunoregulin HA inhibits macrophage maturation and phagocytosis. Mechanically, the activations of c-JUN N-terminal kinase and extracellular signal-regulated kinase upon LPS stimulation are decreased by immunoregulin HA. Consistently, immunoregulin HA treatment exhibits an anti-inflammatory activity in a mouse model of adjuvant-induced paw inflammation. Taken together, our data reveal that immunoregulin HA conducts the anti-inflammatory activity by blocking macrophage functions.

Compound α-keto acid tablet supplementation alleviates chronic kidney disease progression via inhibition of the NF-kB and MAPK pathways

Background

Keto-analogues administration plays an important role in clinical chronic kidney disease (CKD) adjunctive therapy, however previous studies on their reno-protective effect mainly focused on kidney pathological changes induced by nephrectomy. This study was designed to explore the currently understudied alternative mechanisms by which compound α-ketoacid tablets (KA) influenced ischemia–reperfusion (IR) induced murine renal injury, and to probe the current status of KA administration on staving CKD progression in Chinese CKD patients at different stages.

Methods

In animal experiment, IR surgery was performed to mimic progressive chronic kidney injury, while KA was administrated orally. For clinical research, a retrospective cohort study was conducted to delineate the usage and effects of KA on attenuating CKD exacerbation. End-point CKD event was defined as 50% reduction of initial estimated glomerular filtration rate (eGFR). Kaplan–Meier analysis and COX proportional hazard regression model were adopted to calculate the cumulative probability to reach the end-point and hazard ratio of renal function deterioration.

Results

In animal study, KA presented a protective effect on IR induced renal injury and fibrosis by attenuating inflammatory infiltration and apoptosis via inhibition of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. In clinical research, after adjusting basic demographic factors, patients at stages 4 and 5 in KA group presented a much delayed and slower incidence of eGFR decrease compared to those in No-KA group (hazard ratio (HR) = 0.115, 95% confidence interval (CI) 0.021–0.639, p = 0.0134), demonstrating a positive effect of KA on staving CKD progression.

Conclusion

KA improved IR induced chronic renal injury and fibrosis, and seemed to be a prospective protective factor in end stage renal disease.

Housefly (Musca domestica) larvae powder, preventing oxidative stress injury via regulation of UCP4 and CyclinD1 and modulation of JNK and P38 signaling in APP/PS1 mice

Housefly (Musca domestica) Larvae powder (HL) is rich in antioxidants. As oxidative stress is considered as one of the main pathogenesis in Alzheimer's Disease (AD), this study was designed to explore the protective effects of HL as an antioxidant on APP/PS1 mice. 2-Month-old APP/PS1 mice were divided into a model control (MC) group, a Donepezil group and a HL group, and C57BL/6 mice were used as the normal control (NC) group. After 180 days of treatment, the memory ability was measured by Morris Water Maze (MWM). The presence of Aβ and the expression of Uncoupling Protein 4 (UCP4) and CyclinD1 were detected by immunohistochemistry. The expressions of Superoxide Dismutase 1 (SOD1), Catalase (CAT) and Mitogen-activated Protein Kinase (MAPK) signal pathways were measured by western blotting. Compared with untreated APP/PS1 mice, the memory abilities of the HL-treated mice were significantly improved. Furthermore, the HL treatment not only down-regulated the deposition of Aβ and the expression of CylinD1, but also increased both the mRNA and protein levels of SOD, CAT, and UCP4, and enhanced the phosphorylation of JNK and P38 MAPK activation. In conclusion, these results suggest that HL may have a protective effect against memory impairment and prevent oxidative stress-induced injury via the regulation of UCP4 and CyclinD1 and the modulation of JNK and P38 MAPK signaling in AD.

Salidroside Ameliorates Renal Interstitial Fibrosis by Inhibiting the TLR4/NF-κB and MAPK Signaling Pathways

Salidroside (Sal) is an active ingredient that is isolated from Rhodiola rosea, which has been reported to have anti-inflammatory activities and a renal protective effect. However, the role of Sal on renal fibrosis has not yet been elucidated. Here, the purpose of the current study is to test the protective effects of Sal against renal interstitial fibrosis (RIF), and to explore the underlying mechanisms using both in vivo and in vitro models. In this study, we establish the unilateral ureteric obstruction (UUO) or folic acid (FA)-induced mice renal interstitial fibrosis in vivo and the transforming growth factor (TGF)-β1-stimulated human proximal tubular epithelial cell (HK-2) model in vitro. The levels of kidney functional parameters and inflammatory cytokines in serum are examined. The degree of renal damage and fibrosis is determined by histological assessment. Immunohistochemistry and western blotting are used to determine the mechanisms of Sal against RIF. Our results show that treatment with Sal can ameliorate tubular injury and deposition of the extracellular matrix (ECM) components (including collagen Ш and collagen I). Furthermore, Sal administration significantly suppresses epithelial-mesenchymal transition (EMT), as evidenced by a decreased expression of α-SMA, vimentin, TGF-β1, snail, slug, and a largely restored expression of E-cadherin. Additionally, Sal also reduces the levels of serum biochemical markers (serum creatinine, Scr; blood urea nitrogen, BUN; and uric acid, UA) and decreases the release of inflammatory cytokines (IL-1β, IL-6, TNF-α). Further study revealed that the effect of Sal on renal interstitial fibrosis is associated with the lower expression of TLR4, p-IκBα, p-NF-κB and mitogen-activated protein kinases (MAPK), both in vivo and in vitro. In conclusion, Sal treatment improves kidney function, ameliorates the deposition of the ECM components and relieves the protein levels of EMT markers in mouse kidneys and HK-2 cells. Furthermore, Sal treatment significantly decreases the release of inflammatory cytokines and inhibits the TLR4/NF-κB and MAPK signaling pathways. Collectively, these results suggest that the administration of Sal could be a novel therapeutic strategy in treating renal fibrosis.

Macrophage Migration Inhibitor Promoted the Intrahepatic Bile Duct Injury in Rats with Severe Acute Pancreatitis

BACKGROUND

Macrophage migration inhibitory factor (MIF) is involved in many acute and chronic inflammatory diseases. However, its role in intrahepatic bile duct (IBD) cell damage associated with severe acute pancreatitis (SAP) remains unclear.

AIMS

This study was aimed to identify the role of MIF and its underlying mechanisms in SAP complicated by IBD cell damage.

METHODS

Forty-eight specific-pathogen-free male Wistar rats were randomly divided into four groups (N = 12): a sham operation group (SO group) and three SAP model groups (SAP-3h, SAP-6h, and SAP-12h). Immunohistochemistry was used to detect the expression of MIF and P38 in IBD cells. MIF mRNA expression in IBD cells was observed using real-time fluorescent quantitative polymerase chain reaction (real-time PCR). In addition, Western blotting was performed to detect the protein expression of P38, phosphorylated P38 (P-P38), nuclear factor-κB (NF-κB p65), and tumor necrosis factor alpha (TNF-α). Enzyme-linked immunosorbent assays were used to analyze the levels of TNF-α, IL-1β, and IL-6 in the IBD of rats.

RESULTS

Compared with the SO group, the expression of MIF in the IBD was significantly upregulated both at mRNA and at protein levels in the SAP group. Besides, the protein expression levels of P38, P-P38, NF-κB, p65, TNF-α, IL-1β, and IL-6 in the IBD in rats were also significantly increased in the SAP group and the levels increased gradually as acute pancreatitis progressed (all P < 0.05).

CONCLUSIONS

MIF may promote the IBD injury and inflammatory reaction in SAP via activating the P38-MAPK and NF-κB signaling pathways.

Acetyl-macrocalin B suppresses tumor growth in esophageal squamous cell carcinoma and exhibits synergistic anti-cancer effects with the Chk1/2 inhibitor AZD7762

Natural products derived from herbal medicines have become a major focus of anti-cancer drug discovery studies. Acetyl-macrocalin B (A-macB) is an ent-diterpenoid isolated from Isodon silvatica. This study aimed to examine the effect and molecular action of A-macB in esophageal squamous cell carcinoma (ESCC) and explore possible drug synergistic modalities. A-macB induced cellular reactive oxygen species (ROS) generation, initiated the p38 mitogen-activated protein kinase (MAPK) signaling pathway, and triggered the caspase-9-dependent apoptosis cascade in ESCC cells. The ROS scavenger N-acetylcysteine (NAC) and the specific p38 inhibitor SB203580 reversed the effects of A-macB on the p38 network and thus rescued ESCC cells from apoptosis. The cellular ROS increase was at least partially due to the suppression of glutathione-S-transferase P1 (GSTP1) by A-macB. A-macB also upregulated the Chk1/Chk2-Cdc25C/Cdc2/Cyclin B1 axis to induce G2/M phase arrest. The cell growth inhibition induced by A-macB was further enhanced by AZD7762, a specific Chk1/Chk2 inhibitor, with a combination index (CI) of <1. Moreover, A-macB efficiently suppressed xenograft growth without inducing significant toxicity, and AZD7762 potentiated the effects of A-macB in the suppression of tumor growth in vivo. Taken together, A-macB is a promising lead compound for ESCC and exerts synergistic anti-cancer effects with AZD7762.

Blue light negatively affects the survival of ARPE19 cells through an action on their mitochondria and blunted by red light

PURPOSE

To ascertain whether red light, known to enhance mitochondrial function, can blunt a blue light insult to ARPE19 cells in culture.

METHODS

Semi-confluent ARPE19 cells cultured in 10% FBS were subjected to various regimes of treatment with blue (465-475 nm, 800 lux, 26 W/m² ) and red (625-635 nm, 950 lux, 6.5 W/m² ) light, as well as with toxins that inactivate specific enzymes associated with mitochondrial oxidative phosphorylation. Cultures were then analysed for cell viability (MTT assay), mitochondrial status (JC-1), ROS formation, immunocytochemistry and the activation of specific proteins by electrophoresis/Western blotting. In addition, ARPE19 cells were cultured in polycarbonate membrane inserts in culture medium containing 1% FBS. Such cultures were exposed to cycles of red, blue or a combination of red and blue light for up to 6 weeks. Culture medium was changed and the trans-epithelium membrane resistance (TER) of the inserts-containing cells was measured twice weekly.

RESULTS

ARPE19 cells in culture are affected negatively when exposed to blue light. This is indicated by a loss of viability, a depolarization of their mitochondria and a stimulation of ROS. Moreover, blue light causes an up-regulation of HO-1 and phospho-p-38-MAPK and a cleavage of apoptosis inhibitory factor, proteins which are all known to be activated during cell death. All of these negative effects of blue light are significantly blunted by the red light administered after the blue light insult in each case. ARPE19 cell loss of viability and mitochondrial potential caused by toxins that inhibit specific mitochondrial enzyme complexes was additive to an insult delivered by blue light in each case. After a time, ARPE19 cells in culture express the tight junction protein ZO-1, which is affected by blue light. The development of tight junctions between ARPE19 cells grown in inserts reached a steady peak of resistance after about 40 days and then increased very slightly over the next 40 days when still in darkness. However, maximum resistance was significantly attenuated, when cultures were treated with cycles of blue light after the initial 40 days in the dark and counteracted significantly when the blue light cycle insult was combined with red light.

CONCLUSION

Blue light affects mitochondrial function and also the development tight junctions between ARPE19 cells, which results in a loss of cell viability. Importantly, red light delivered after a blue light insult is significantly blunted. These findings argue for the therapeutic use of red light as a noninvasive procedure to attenuate insults caused by blue light and other insults to retinal pigment epithelial cell mitochondria that are likely to occur in age-related macular degeneration.

Protein-ligand interaction fingerprints for accurate prediction of dissociation rates of p38 MAPK Type II inhibitors

Binding/unbinding kinetics are key determinants of drug potencies. However, there are still a lot of challenges in predicting kinetic properties during early-stage drug development. In this work, position-restrained molecular dynamics simulations combined with energy decomposition were applied to extract protein-ligand interaction (PLI) fingerprints along the unbinding pathway of 20 p38 mitogen-activated protein kinase (p38 MAPK) Type II inhibitors. The results showed that the electrostatic and/or van der Waals interaction fingerprints at three key positions can be used for accurate prediction of the dissociation rate constants (koff) of p38 MAPK Type II inhibitors. The strategy proposed in this paper can provide not only an efficient method of predicting the dissociation rates of the p38 MAPK Type II inhibitors, but also the atom-level mechanism of enthalpy-driven unbinding process.

P38 is involved in immune response by regulating inflammatory cytokine expressions in the Pacific oyster Crassostrea gigas

P38 mitogen-activated protein kinases are serine/threonine protein kinases reportedly involved in the innate immunity of vertebrates and invertebrates. In the present study, a P38 homolog (CgP38) was characterized from the Pacific oyster Crassostrea gigas. The full-length cDNA of CgP38 was of 1515 bp containing a 1101 bp open reading frame. A serine/threonine protein kinase (S_TKc) domain with a conserved Thr-Gly-Tyr motif and an ATRW substrate-binding site was found in the deduced amino acid sequence of CgP38. CgP38 shared a close evolutionary relationship with ChP38 from the Hong Kong oyster Crassostrea hongkongensis. The transcript levels of CgP38 in hemocytes increased significantly from 12 h to 48 h after lipopolysaccharide (LPS) stimulation and from 12 h to 24 h after Vibrio splendidus stimulation. The phosphorylation level of CgP38 in oyster hemocytes increased significantly at 2 h after LPS stimulation. CgP38 positively regulated the expression of interleukins, such as CgIL17-1, CgIL17-2, CgIL17-3, CgIL17-4 and CgIL17-6, and tumor necrosis factor CgTNF after LPS or V. splendidus stimulation. These results suggested that CgP38 participated in oyster immune response by regulating the expressions of inflammatory cytokines.

Smp38 MAP Kinase Regulation in Schistosoma mansoni: Roles in Survival, Oviposition, and Protection Against Oxidative Stress

Eukaryotic protein kinases (ePKs) are good medical targets for drug development in different biological systems. ePKs participate in many cellular processes, including the p38 MAPK regulation of homeostasis upon oxidative stress. We propose to assess the role of Smp38 MAPK signaling pathway in Schistosoma mansoni development and protection against oxidative stress, parasite survival, and also to elucidate which target genes have their expression regulated by Smp38 MAPK. After a significant reduction of up to 84% in the transcription level by Smp38 MAPK gene knockdown, no visible phenotypic changes were reported in schistosomula in culture. The development of adult worms was tested in vivo in mice infected with the Smp38 knocked-down schistosomula. It was observed that Smp38 MAPK has an essential role in the transformation and survival of the parasites as a low number of adult worms was recovered. Smp38 knockdown also resulted in decreased egg production, damaged adult worm tegument, and underdeveloped ovaries in females. Furthermore, only ~13% of the eggs produced developed into mature eggs. Our results suggest that inhibition of the Smp38 MAPK activity interfere in parasites protection against reactive oxygen species. Smp38 knockdown in adult worms resulted in 80% reduction in transcription levels on the 10th day, with consequent reduction of 94.4% in oviposition in vitro. In order to search for Smp38 MAPK pathway regulated genes, we used an RNASeq approach and identified 1,154 DEGs in Smp38 knockdown schistosomula. A substantial proportion of DEGs encode proteins with unknown function. The results indicate that Smp38 regulates essential signaling pathways for the establishment of parasite homeostasis, including genes related to antioxidant defense, structural composition of ribosomes, spliceosomes, cytoskeleton, as well as, purine and pyrimidine metabolism pathways. Our data show that the Smp38 MAPK signaling pathway is a critical route for parasite development and may present attractive therapeutic targets for the treatment and control of schistosomiasis.

Synthesis and Evaluation of a New Type of Small Molecule Epigenetic Modulator Containing Imidazo[1,2-b][1,2,4]triazole Motif

Epigenetic modifications such as DNA methylation is important for many cellular processes, such as cell differentiation and cell death. The disorder of epigenetic state is closely related to human diseases, especially cancers. DNA methylation is a well-characterized epigenetic modification which is related to gene silencing and is considered as a repressive epigenetic mark. DNA methylation caused gene repression can be derepressed by chemical agents. Small molecules targeting DNA methyltransferases, histone deacetylases, and other regulatory factors can activate genes silenced by DNA methylation. However, more and more studies have shown that histone deacetylation is not the only downstream event of DNA methylation. Some additional, unknown mechanisms that promote DNA methylation-mediated gene silencing may exist. Recently, through high-throughput screening using a 308,251-member chemical library to identify potent small molecules that derepress an EGFP reporter gene silenced by DNA methylation, we identified seven hit compounds that did not directly target bulk DNA methylation or histone acetylation. Three of them (LX-3, LX-4, LX-5) were proven to selectively activate the p38 MAPK pathway in multiple cell types. In order to identify the exact cellular targets of these compounds, we turn to work on the SAR study of LX-3 by constructing a structurally diverse chemical library based on the imidazo[1,2-b][1,2,4]triazole core structure via diversity-oriented synthesis. Our work provides a general approach to efficiently access diverse heterocyclic molecules with interesting epigenetic modulation activities.

ΔNp63α modulates phosphorylation of p38 MAP kinase in regulation of cell cycle progression and cell growth

p53-related p63 plays a critical role in regulation of cell proliferation, survival and cell differentiation. Dysregulation of p63 functions results in a disruption of a variety of normal biological processes, including stem cell biology, embryonic development, aging and tumorigenesis. ΔNp63α, a predominantly expressed p63 protein isoform in epithelial cells, plays a crucial role in regulation of cell cycle progression and cell growth. p38 MAP kinases (p38MAPK) are the members of mitogen-activated protein kinases family and are critical in regulation of cell survival in response to stress signals. In this study, we show that ectopic expression of ΔNp63α inhibited phosphorylation of p38MAPK. Acute knockdown of p63 led to a significant upregulation of p38MAPK phosphorylation, resulting in increased p21^cip1/waf1 expression, reduced phosphorylation of retinoblastoma protein (RB), cell cycle G1 arrest and cell growth retardation. Restoration of ΔNp63α expression reversed cell cycle arrest and growth inhibition induced by p63 ablation. Pharmacological inhibition of p38MAPK significantly suppressed ΔNp63α ablation-induced cell cycle G1/S arrest. In addition, MAP Kinase Phosphatase 3 (MKP3) was responsible for ΔNp63α-mediated regulation of p38MAPK phosphorylation. Together, these results suggest that ΔNp63α-MPK3-p38MAPK signaling pathway plays an important role in cell cycle progression and cell growth.

Vitronectin, fibronectin and epidermal growth factor induce proliferation via the JNK and ERK pathways in insulinoma INS-1 cells

An insulinoma is a tumor formed by beta cells in the Langerhans islets of the pancreas. Vitronectin (VTN), fibronectin (FN) and epidermal growth factor (EGF) are important in cell signaling. The aim of this study was to investigate the molecular mechanism that occurs in INS-1 cells with the administration of VTN, FN and EGF in proliferative doses. We determined the proliferative doses of EGF, VTN and FN. The molecular mechanism of proliferation has been investigated alone or in the combination of these proteins. It was observed that INS-1 cells did not have VTN and FN. Cell viability increased with the administration of 0.1 μg/ml VTN, 0.1 μg/ml FN and 1 mg/ml EGF. Proliferation increased with the administration of FN + EGF, and VTN + FN + EGF together when compared to the control group. The total JNK levels did not change between the groups; however, the active JNK levels increased in the VT + FN + EGF group compared to the control group. The total ERK levels increased in the VT + FN + EGF group, and the active ERK levels increased in the VTN + FN, VTN + EGF and VTN + FN + EGF groups compared to the control group. The JNK and ERK pathways are important for proliferation. The JNK and ERK pathways were activated in VTN + FN + EGF administered group. However, it was observed that the ERK pathway was more active than the JNK pathway.

Molecular characterization of p38 MAPK from blunt snout bream (Megalobrama amblycephala) and its expression after ammonia stress, and lipopolysaccharide and bacterial challenge

p38 mitogen-activated protein kinase (MAPK) is an important protein which plays a key role in regulating the innate immunity, so exploring its molecular characterization is helpful in understanding the resistance against microbial infections in cultured fish. Here, a full-length cDNA of p38 MAPK was cloned from liver of blunt snout bream (Megalobrama amblycephala) which covered 2419 bp with an open reading frame of 1086 bp encoding 361 amino acids. p38 MAPK contained the characteristic structures of Thr-Gly-Tyr (TGY) motif and substrate binding site Ala-Thr-Arg-Trp (ATRW), which are conserved in MAPK family. To investigate p38 MAPK functions, two in vivo experiments were carried out to examine its expression following ammonia exposure and bacterial challenge. Also, an in vitro experiment was conducted to assess the role of p38 MAPK in inflammation of primary hepatocytes induced by lipopolysaccharide (LPS). The results showed the ubiquitous expression of p38 MAPK in all the tested tissues with varying levels. p38 MAPK mRNA expression was significantly up-regulated by ammonia stress and Aeromonas hydrophila challenge, and altered in a time-dependent manner. Moreover, the results indicated that the inflammatory response induced by LPS in hepatocytes is p38 MAPK dependent as knockdown of p38 MAPK using siRNA technology depressed the expression of IL-1β and IL-6. The findings in this study showed that p38 MAPK has anti-stress property, and plays key role in protection against bacterial infection and inflammation in blunt snout bream.

Upregulation of UBAP2L in Bone Marrow Mesenchymal Stem Cells Promotes Functional Recovery in Rats with Spinal Cord Injury

Post-translational modifications of cellular proteins with ubiquitin or ubiquitin-like proteins regulate many cellular processes, such as cell proliferation, differentiation, apoptosis, signal transduction, intercellular immune recognition, inflammatory response, stress response, and DNA repair. Nice4/UBAP2L is an important member in the family of ubiquitin-like proteins, and its biological function remains unknown. This study aimed to investigate the effect of UBAP2L on spinal cord injury (SCI). At first, rat bone marrow mesenchymal stem cells (BMSCs) were infected with adeno-associated virus to induce over-expression of Nice4. Subsequently, the infected BMSCs were transplanted into rats suffering from semi-sectioned SCI. The results showed that the over-expression of Nice4 significantly promoted the proliferation and differentiation of BMSCs. In addition, the transplantation of infected BMSCs into the injured area of SCI rats improved the function repair of SCI. Importantly, the immunohistochemical and hematoxylin-eosin staining and RT-PCR results showed that the number of neuronal cells, oligodendrocytes, and astrocytes was significantly increased in the injured area, along with significantly upregulated expression of cyclin D1 and p38 mitogen-activated protein kinase (MAPK). Meanwhile, the expression of caspase 3 protein was significantly down-regulated. In conclusion, the over-expression of Nice4 gene can promote the functional recovery in SCI rats by promoting cell proliferation and inhibiting apoptosis. The results of this study indicate an alternative option for the clinical treatment of SCI.