Phosphorylation of c-Fos by members of the p38 MAPK family. Role in the AP-1 response to UV light

Iron-triggered signaling via ETS1 and the p38/JNK MAPK pathway regulates Bmp6 expression

BMP6 is an iron-sensing cytokine whose transcription in liver sinusoidal endothelial cells (LSECs) is enhanced by high iron levels, a step that precedes the induction of the iron-regulatory hormone hepcidin. While several reports suggested a cell-autonomous induction of Bmp6 by iron-triggered signals, likely via sensing of oxidative stress by the transcription factor NRF2, other studies proposed the dominant role of a paracrine yet unidentified signal released by iron-loaded hepatocytes. To further explore the mechanisms of Bmp6 transcriptional regulation, we used female mice aged 10-11 months, which are characterized by hepatocytic but not LSEC iron accumulation, and no evidence of systemic iron overload. We found that LSECs of aged mice exhibit increased Bmp6 mRNA levels as compared to young controls, but do not show a transcriptional signature characteristic of activated NFR2-mediated signaling in FACS-sorted LSECs. We further observed that primary murine LSECs derived from both wild-type and NRF2 knock-out mice induce Bmp6 expression in response to iron exposure. By analyzing transcriptomic data of FACS-sorted LSECs from aged versus young mice, as well as early after iron citrate injections, we identified ETS1 as a candidate transcription factor involved in Bmp6 transcriptional regulation. By performing siRNA-mediated knockdown, small-molecule treatments, and chromatin immunoprecipitation in primary LSECs, we show that Bmp6 transcription is regulated by iron via ETS1 and p38/JNK MAP kinase-mediated signaling, at least in part independently of NRF2. Thereby, these findings identify the new components of LSEC iron sensing machinery broadly associated with cellular stress responses.

Hypermigration of macrophages through the concerted action of GRA effectors on NF-κB/p38 signaling and host chromatin accessibility potentiates Toxoplasma dissemination

Mononuclear phagocytes facilitate the dissemination of the obligate intracellular parasite Toxoplasma gondii. Here, we report how a set of secreted parasite effector proteins from dense granule organelles (GRA) orchestrates dendritic cell-like chemotactic and pro-inflammatory activation of parasitized macrophages. These effects enabled efficient dissemination of the type II T. gondii lineage, a highly prevalent genotype in humans. We identify novel functions for effectors GRA15 and GRA24 in promoting CCR7-mediated macrophage chemotaxis by acting on NF-κB and p38 MAPK signaling pathways, respectively, with contributions of GRA16/18 and counter-regulation by effector TEEGR. Further, GRA28 boosted chromatin accessibility and GRA15/24/NF-κB-dependent transcription at the Ccr7 gene locus in primary macrophages. In vivo, adoptively transferred macrophages infected with wild-type T. gondii outcompeted macrophages infected with a GRA15/24 double mutant in migrating to secondary organs in mice. The data show that T. gondii, rather than being passively shuttled, actively promotes its dissemination by inducing a finely regulated pro-migratory state in parasitized human and murine phagocytes via co-operating polymorphic GRA effectors.

IFITM3-mediated activation of TRAF6/MAPK/AP-1 pathways induces acquired TKI resistance in clear cell renal cell carcinoma

PURPOSE

Vascular endothelial growth factor tyrosine kinase inhibitors (TKIs) have been the standard of care for advanced and metastatic clear cell renal cell carcinoma (ccRCC). However, the therapeutic effect of TKI monotherapy remains unsatisfactory given the high rates of acquired resistance to TKI therapy despite favorable initial tumor response.

MATERIALS AND METHODS

To define the TKI-resistance mechanism and identify new therapeutic target for TKI-resistant ccRCC, an integrative differential gene expression analysis was performed using acquired resistant cohort and a public dataset. Sunitinib-resistant RCC cell lines were established and used to test their malignant behaviors of TKI resistance through in vitro and in vivo studies. Immunohistochemistry was conducted to compare expression between the tumor and normal kidney and verify expression of pathway-related proteins.

RESULTS

Integrated differential gene expression analysis revealed increased interferon-induced transmembrane protein 3 (IFITM3) expression in post-TKI samples. IFITM3 expression was increased in ccRCC compared with the normal kidney. TKI-resistant RCC cells showed high expression of IFITM3 compared with TKI-sensitive cells and displayed aggressive biologic features such as higher proliferative ability, clonogenic survival, migration, and invasion while being treated with sunitinib. These aggressive features were suppressed by the inhibition of IFITM3 expression and promoted by IFITM3 overexpression, and these findings were confirmed in a xenograft model. IFITM3-mediated TKI resistance was associated with the activation of TRAF6 and MAPK/AP-1 pathways.

CONCLUSIONS

These results demonstrate IFITM3-mediated activation of the TRAF6/MAPK/AP-1 pathways as a mechanism of acquired TKI resistance, and suggest IFITM3 as a new target for TKI-resistant ccRCC.

Interplay of Chemokines Receptors, Toll-like Receptors, and Host Immunological Pathways

A comprehensive framework has been established for understanding immunological pathways, which can be categorized into eradicated and tolerable immune responses. Toll-like receptors (TLRs) are associated with specific immune responses. TH1 immunity is related to TLR7, TLR8, and TLR9, while TH2 immunity is associated with TLR1, TLR2, and TLR6. TH22 immunity is linked to TLR2, TLR4, and TLR5, and THαβ (Tr1) immunity is related to TLR3, TLR7, and TLR9. The chemokine receptor CXCR5 is a marker of follicular helper T cells, and other chemokine receptors can also be classified within a framework based on host immunological pathways. On the basis of a literature review on chemokines and immunological pathways, the following associations were identified: CCR5 with TH1 responses, CCR1 with TH1-like responses, CCR4 (basophils) and CCR3 (eosinophils) with TH2 and TH9 responses, CCR10 with TH22 responses, CCR6 with TH17 responses, CXCR3 with THαβ responses, CCR8 with regulatory T cells (Treg), and CCR2 with TH3 responses. These findings contribute to the identification of biomarkers for immune cells and provide insights into host immunological pathways. Understanding the chemokine and Toll-like receptor system is crucial for comprehending the function of the innate immune system, as well as adaptive immune responses.

The potential of activator protein 1 (AP-1) in cancer targeted therapy

Activator protein-1 (AP-1) is a transcription factor that consists of a diverse group of members including Jun, Fos, Maf, and ATF. AP-1 involves a number of processes such as proliferation, migration, and invasion in cells. Dysfunctional AP-1 activity is associated with cancer initiation, development, invasion, migration and drug resistance. Therefore, AP-1 is a potential target for cancer targeted therapy. Currently, some small molecule inhibitors targeting AP-1 have been developed and tested, showing some anticancer effects. However, AP-1 is complex and diverse in its structure and function, and different dimers may play different roles in different type of cancers. Therefore, more research is needed to reveal the specific mechanisms of AP-1 in cancer, and how to select appropriate inhibitors and treatment strategies. Ultimately, this review summarizes the potential of combination therapy for cancer.

Endothelin Receptor-A Inhibition Decreases Ductular Reaction, Liver Fibrosis, and Angiogenesis in a Model of Cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) leads to ductular reaction and fibrosis and is complicated by vascular dysfunction. Cholangiocyte and endothelial cell crosstalk modulates their proliferation in cholestatic models. Endothelin (ET)-1 and ET-2 bind to their receptor, ET-A, and cholangiocytes are a key source of ET-1 after bile duct ligation. We aimed to evaluate the therapeutic potential of ET-A inhibition in PSC and biliary-endothelial crosstalk mediated by this pathway.

METHODS

Wild-type and multidrug resistance 2 knockout (Mdr2-/-) mice at 12 weeks of age were treated with vehicle or Ambrisentan (ET-A antagonist) for 1 week by daily intraperitoneal injections. Human control and PSC samples were used.

RESULTS

Mdr2-/- mice at 4, 8, and 12 weeks displayed angiogenesis that peaked at 12 weeks. Mdr2-/- mice at 12 weeks had enhanced biliary ET-1/ET-2/ET-A expression and secretion, whereas human PSC had enhanced ET-1/ET-A expression and secretion. Ambrisentan reduced biliary damage, immune cell infiltration, and fibrosis in Mdr2-/- mice. Mdr2-/- mice had squamous cholangiocytes with blunted microvilli and dilated arterioles lacking cilia; however, Ambrisentan reversed these alterations. Ambrisentan decreased cholangiocyte expression of pro-angiogenic factors, specifically midkine, through the regulation of cFOS. In vitro, ET-1/ET-A caused cholangiocyte senescence, endothelial cell angiogenesis, and macrophage inflammation. In vitro, human PSC cholangiocyte supernatants increased endothelial cell migration, which was blocked with Ambrisentan treatment.

CONCLUSIONS

ET-A inhibition reduced biliary and liver damage in Mdr2-/- mice. ET-A promotes biliary angiocrine signaling that may, in turn, enhance angiogenesis. Targeting ET-A may prove therapeutic for PSC, specifically patients displaying vascular dysfunction.

Protective effects of volatile components of aged garlic extract against ultraviolet B-induced apoptosis in human skin fibroblasts

Aged garlic extract (AGE) has been shown to protect the skin against UV-induced damage, but effects of its volatile components remain unknown. We investigated the effects of the volatile fraction of AGE on the responses of cultured skin fibroblasts subjected to UV-B irradiation. UV-B irradiation (20 mJ/cm² ) reduced the cell viability to 55% of control. The nonvolatile and volatile fractions of AGE inhibited the UV-B-induced reduction of cell viability; the cell viabilities were 100% and 73%, respectively. The volatile fraction inhibited the UV-B-induced increase in apoptotic cell death by 28%. The volatile fraction also inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) induced by UV-B irradiation. GC-MS analysis revealed that a large number of volatile compounds were generated during aging of garlic. These results suggest that the volatile fraction of AGE has protective effects against the UV-B-induced death of skin fibroblasts, and that this effect may partly be due to an inhibition of apoptosis via the downregulation of MAPK signaling. The volatile compounds of AGE may have beneficial applications for skin health. PRACTICAL APPLICATIONS: In this study, we investigated the effects of AGE against cell damage of UV-B-irradiated human skin fibroblasts. The aging process of garlic produced characteristic volatile compounds that have significant protective effects against UV-induced cell damage. Our results demonstrated that the aging process is a suitable method to develop added value in garlic extracts to improve skin health.

The Role of Probiotics in Skin Photoaging and Related Mechanisms: A Review

Solar ultraviolet radiation (UVR) is the primary pathogenetic factor in skin photoaging. It can disrupt cellular homeostasis by damaging DNA, inducing an inflammatory cascade, immunosuppression, and extracellular matrix (ECM) remodeling, resulting in a variety of dermatologic conditions. The skin microbiome plays an important role in the homeostasis and maintenance of healthy skin. Emerging evidence has indicated that highly diverse gut microbiome may also have an impact on the skin health, referred to as the gut-skin axis (GSA). Oral and topical probiotics through modulating the skin microbiome and gut-skin microbial interactions could serve as potential management to prevent and treat the skin photoaging by multiple pathways including reducing oxidative stress, inhibiting ECM remodeling, inhibiting the inflammatory cascade reaction, and maintaining immune homeostasis. In this review, the effects of oral and topical probiotics in skin photoaging and related mechanisms are both described systematically and comprehensively.

Unlocking the Untapped Potential of Endothelial Kinase and Phosphatase Involvement in Sepsis for Drug Treatment Design

Sepsis is a devastating clinical condition that can lead to multiple organ failure and death. Despite advancements in our understanding of molecular mechanisms underlying sepsis and sepsis-associated multiple organ failure, no effective therapeutic treatment to directly counteract it has yet been established. The endothelium is considered to play an important role in sepsis. This review highlights a number of signal transduction pathways involved in endothelial inflammatory activation and dysregulated endothelial barrier function in response to sepsis conditions. Within these pathways – NF-κB, Rac1/RhoA GTPases, AP-1, APC/S1P, Angpt/Tie2, and VEGF/VEGFR2 – we focus on the role of kinases and phosphatases as potential druggable targets for therapeutic intervention. Animal studies and clinical trials that have been conducted for this purpose are discussed, highlighting reasons why they might not have resulted in the expected outcomes, and which lessons can be learned from this. Lastly, opportunities and challenges that sepsis and sepsis-associated multiple organ failure research are currently facing are presented, including recommendations on improved experimental design to increase the translational power of preclinical research to the clinic.

Fluid shear stress enhances T cell activation through Piezo1

Background

T cell activation is a mechanical process as much as it is a biochemical process. In this study, we used a cone-and-plate viscometer system to treat Jurkat and primary human T cells with fluid shear stress (FSS) to enhance the activation of the T cells through mechanical means.

Results

The FSS treatment of T cells in combination with soluble and bead-bound CD3/CD28 antibodies increased the activation of signaling proteins essential for T cell activation, such as zeta-chain-associated protein kinase-70 (ZAP70), nuclear factor of activated T cells (NFAT), nuclear factor kappa B (NF-κB), and AP-1 (activator protein 1). The FSS treatment also enhanced the expression of the cytokines tumor necrosis factor alpha (TNF-α), interleukin 2 (IL-2), and interferon gamma (IFN-γ), which are necessary for sustained T cell activation and function. The enhanced activation of T cells by FSS was calcium dependent. The calcium signaling was controlled by the mechanosensitive ion channel Piezo1, as GsMTx-4 and Piezo1 knockout reduced ZAP70 phosphorylation by FSS.

Conclusions

These results demonstrate an intriguing new dynamic to T cell activation, as the circulatory system consists of different magnitudes of FSS and could have a proinflammatory role in T cell function. The results also identify a potential pathophysiological relationship between T cell activation and FSS, as hypertension is a disease characterized by abnormal blood flow and is correlated with multiple autoimmune diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01266-7.

DZNep promotes mouse bone defect healing via enhancing both osteogenesis and osteoclastogenesis

Background

Enhancer of zeste homolog 2 (EZH2) is a novel oncogene that can specifically trimethylate the histone H3 lysine 27 (H3K27me3) to transcriptionally inhibit the expression of downstream tumor-suppressing genes. As a small molecular inhibitor of EZH2, 3-Deazaneplanocin (DZNep) has been widely studied due to the role of tumor suppression. With the roles of epigenetic regulation of bone cells emerged in past decades, the property and molecular mechanism of DZNep on enhancing osteogenesis had been reported and attracted a great deal of attention recently. This study aims to elucidate the role of DZNep on EZH2-H3K27me3 axis and downstream factors during both osteoclasts and osteoblasts formation and the therapeutic possibility of DZNep on bone defect healing.

Methods

Bone marrow-derived macrophages (BMMs) cells were cultured, and their responsiveness to DZNep was evaluated by cell counting kit-8, TRAP staining assay, bone resorption assay, podosome actin belt. Bone marrow-derived mesenchymal stem cells (BMSC) were cultured and their responsiveness to DZNep was evaluated by cell counting kit-8, ALP and AR staining assay. The expression of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), Wnt signaling pathway was determined by qPCR and western blotting. Mouse bone defect models were created, rescued by DZNep injection, and the effectiveness was evaluated by X-ray and micro-CT and histological staining.

Results

Consistent with the previous study that DZNep enhances osteogenesis via Wnt family member 1(Wnt1), Wnt6, and Wnt10a, our results showed that DZNep also promotes osteoblasts differentiation and mineralization through the EZH2-H3K27me3-Wnt4 axis. Furthermore, we identified that DZNep promoted the receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast formation via facilitating the phosphorylation of IKKα/β, IκB, and subsequently NF-κB nuclear translocation, which credit to the EZH2-H3K27me3-Foxc1 axis. More importantly, the enhanced osteogenesis and osteoclastogenesis result in accelerated mice bone defect healing in vivo.

Conclusion

DZNep targeting EZH2-H3K27me3 axis facilitated the healing of mice bone defect via simultaneously enhancing osteoclastic bone resorption and promoting osteoblastic bone formation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02670-6.

Association between HO‑1 gene promoter polymorphisms and diseases (Review)

Heme oxygenase‑1 (HO‑1) is an inducible cytoprotective enzyme that degrades heme into free iron, carbon monoxide and biliverdin, which is then rapidly converted into bilirubin. These degradation products serve an important role in the regulation of inflammation, oxidative stress and apoptosis. While the expression level of HO‑1 is typically low in most cells, it may be highly expressed when induced by a variety of stimulating factors, a process that contributes to the regulation of cell homeostasis. In the 5'‑non‑coding region of the HO‑1 gene, there are two polymorphic sites, namely the (GT)n dinucleotide and T(‑413)A single nucleotide polymorphism sites, which regulate the transcriptional activity of HO‑1. These polymorphisms have been shown to be closely associated with the occurrence and progression of numerous diseases, including cardiovascular, pulmonary, liver and kidney, various types of cancer and viral diseases. The present article reviews the progress that has been made in research on the association between the two types of polymorphisms and these diseases, which is expected to provide novel strategies for the diagnosis, treatment and prognosis of various diseases.

Luteolin Prevents UVB-Induced Skin Photoaging Damage by Modulating SIRT3/ROS/MAPK Signaling: An in vitro and in vivo Studies

The aim of this study was to investigate the role of luteolin in the mechanism of ultraviolet radiation B (UVB)-induced photoaging. An in vivo photoaging model was established using UVB irradiation of bare skin on the back of rats, and an in vitro photoaging model was established using UVB irradiation of human dermal fibroblasts (HDF). Skin damage was observed using hematoxylin-eosin (HE) and Masson staining, skin and cellular reactive oxygen species (ROS) levels were detected by DHE and DCF fluorescent probes, mitochondrial membrane potential was detected by JC-1 staining, and protein expressions were detected by immunofluorescence and Western Blot. Results from animal experiments showed that luteolin reduced UVB-induced erythema and wrinkle formation. Results from cellular assays showed that luteolin inhibited UVB-induced decrease in cell viability. In addition, in vitro and in vivo experiments showed that luteolin reduced oxidative stress levels, decreased activation of matrix metalloproteinases (MMPs) and increased collagen expression. Continued cellular experiments using 3-TYP, an inhibitor of Sirtuin 3 (SIRT3), revealed a loss of cellular protection by luteolin and a decrease in collagen, suggesting that luteolin acts by targeting and promoting SIRT3. luteolin is involved in the protection of skin cells against UVB radiation-induced ageing via the SIRT3/ROS/mitogen-activated protein kinases (MAPK) axis and it may be a promising therapeutic agent for the prevention of UVB photoaging.

Crucial role of glucosylceramide synthase in the regulation of stem cell-like cancer cells in B16F10 murine melanoma

Cancer stem cells render a complex cascade of events that facilitates highly invasive melanoma malignancy. Interplay between immunocytes and cancer stem cells within tumor microenvironment with the participation of sphingolipid signaling mediators skews the immune evasion strategies toward metastatic neoplasm. In this context, we aimed to explore the functional aspect of glucosylceramide synthase (GCS), a key enzyme of sphingolipid biosynthesis in the maintenance of melanoma stem cell-like cancer cells (CSCs). Our findings demonstrated that tumor hypoxia was responsible for elevated GCS expression in melanoma, which was correlated with substantially increased melanoma CSCs. Moreover, hypoxia-induced TGF-β from TAMs and Tregs promoted GCS induction in B16F10 murine melanoma CSCs via PKCα signaling and facilitated the expansion of melanoma CSCs. Interestingly, GCS ablation hindered the immunosuppressiveness of TAMs and Tregs. Therefore, our study for the first time demonstrated a novel paracrine pathway of melanoma CSC maintenance and tumorigenicity, exploiting the bidirectional signaling with immunocytes. Furthermore, our study showed that the combinatorial immunotherapy involving immunomodulators like Mw and DTA-1 repressed CSC pool affecting GCS functions in advanced-stage B16F10 murine melanoma tumor. Moreover, GCS inhibition sensitized conventional chemotherapeutic drug-resistant melanoma CSCs to the genotoxic drugs paving the way toward selective melanoma treatment. Better therapeutic efficacy with inhibition of GCS and CSC depletion suggests a crucial role of GCS in melanoma treatment, therefore, implying its application concerning clinical challenges of chemotherapy resistance leading to prolonged survival.

The FOS/AP-1 Regulates Metabolic Changes and Cholesterol Synthesis in Human Periovulatory Granulosa Cells

FOS, a subunit of the activator protein-1 (AP-1) transcription factor, has been implicated in various cellular changes. In the human ovary, the expression of FOS and its heterodimeric binding partners JUN, JUNB, and JUND increases in periovulatory follicles. However, the specific role of the FOS/AP-1 remains elusive. The present study determined the regulatory mechanisms driving the expression of FOS and its partners and functions of FOS using primary human granulosa/lutein cells (hGLCs). Human chorionic gonadotropin (hCG) induced a biphasic increase in the expression of FOS, peaking at 1 to 3 hours and 12 hours. The levels of JUN proteins were also increased by hCG, with varying expression patterns. Coimmunoprecipitation analyses revealed that FOS is present as heterodimers with all JUN proteins. hCG immediately activated protein kinase A and p42/44MAPK signaling pathways, and inhibitors for these pathways abolished hCG-induced increases in the levels of FOS, JUN, and JUNB. To identify the genes regulated by FOS, high-throughput RNA sequencing was performed using hGLC treated with hCG ± T-5224 (FOS inhibitor). Sequencing data analysis revealed that FOS inhibition affects the expression of numerous genes, including a cluster of genes involved in the periovulatory process such as matrix remodeling, prostaglandin synthesis, glycolysis, and cholesterol biosynthesis. Quantitative PCR analysis verified hCG-induced, T-5224-regulated expression of a selection of genes involved in these processes. Consistently, hCG-induced increases in metabolic activities and cholesterol levels were suppressed by T-5224. This study unveiled potential downstream target genes of and a role for the FOS/AP-1 complex in metabolic changes and cholesterol biosynthesis in granulosa/lutein cells of human periovulatory follicles.

Protein phosphatase 1 regulatory subunit 18 suppresses the transcriptional activity of NFATc1 via regulation of c-fos

The transcription factor NFATc1 and its binding partner AP-1 (a complex containing c-fos and c-Jun) play a central role in osteoclast differentiation. NFATc1 and AP-1 promote the expression of target genes such as Acp5, Ctsk and also auto-regulate NFATc1 expression as well. We previously reported that protein phosphatase 1 regulatory subunit 18 (PPP1r18) is a negative regulator of osteoclast bone resorption by inhibiting cell attachment to bone matrix. We also reported that PPP1r18 potentially regulates NFATc1 expression during osteoclast differentiation. To further explore this, in this study we have examined the effect of PPP1r18 on NFATc1 expression and activity by overexpressing PPP1r18 during the early stage of osteoclast differentiation. We found that PPP1r18 suppressed NFATc1 expression through inhibition of the transcriptional activity of NFATc1. Since PPP1r18 does not regulate NFATc1 directly, we next explored the involvement of AP-1. Our data showed that c-fos phosphorylation and nuclear localization were reduced by PPP1r18 overexpression. Further experiments showed that overexpression of c-fos together with PPP1r18 rescued NFATc1 expression and transcriptional activity. Moreover, c-fos activity inhibition by PPP1r18 was canceled by mutation of the phosphatase binding site of PPP1r18. Taken together, PPP1r18-regulated phosphatase activity targets c-fos phosphorylation and suppresses subsequent NFATc1 expression and activity.

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PPP1r18 suppresses osteoclast differentiation.

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PPP1r18 suppresses c-fos phosphorylation and nuclear localization.

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PPP1r18 suppresses NFAT via c-fos.

Signaling of MK2 sustains robust AP1 activity for triple negative breast cancer tumorigenesis through direct phosphorylation of JAB1

Triple negative breast cancer (TNBC) cells are generally more invasive than estrogen receptor-positive (ER + ) breast cancer cells. Consistent with the importance of activator protein 1 (AP1) transcription factors in invasion, AP1 activity is much higher in TNBC lines than ER + lines. In TNBC cells, robust AP1 activity is facilitated by both ERK and p38^MAPK signaling pathways. While ERK signaling pathway regulates AP1 activity by controlling the abundance of AP1 transcription factors, p38^MAPK signaling pathway does it by enhancing AP1 binding to AP1 sites without altering their abundance. Here, we show that p38^MAPK regulation of AP1 activity involves both MAPKAPK2 (MK2) and JAB1, a known JUN-binding protein. MK2 not only interacts with JAB1 but also directly phosphorylates JAB1 at Ser177 in TNBC cells. Interestingly, Ser177 phosphorylation does not affect JAB1 and JUN interaction. Instead, interfering with p38^MAPK signaling pathway or introducing an S to A point mutation at Ser177 of JAB1 reduces JUN recruitment to the AP1 sites in cyclin D1, urokinase plasminogen activator (uPA) and uPA receptor promoters. Moreover, knockdown of JAB1 diminishes >60% of AP1 transcriptional activity in TNBC cells. Taken together, these results indicate that MK2-mediated phosphorylation of JAB1 facilitates JUN recruitment to AP1 sites, thus augmenting AP1 activity. In line with the role of JAB1 in AP1 activity, silencing JAB1 leads to dramatic reduction in TNBC cell growth, in vitro invasion and in vivo tumor outgrowth. This study suggests that the p38^MAPK-MK2 signaling pathway promotes TNBC tumorigenesis by sustaining robust AP1 activity.

Methylmercury induces neuronal cell death by inducing TNF-α expression through the ASK1/p38 signaling pathway in microglia

We recently found that tumor necrosis factor-α (TNF-α) may be involved in neuronal cell death induced by methylmercury in the mouse brain. Here, we examined the cells involved in the induction of TNF-α expression by methylmercury in the mouse brain by in situ hybridization. TNF-α-expressing cells were found throughout the brain and were identified as microglia by immunostaining for ionized calcium binding adaptor molecule 1 (Iba1). Methylmercury induced TNF-α expression in mouse primary microglia and mouse microglial cell line BV2. Knockdown of apoptosis signal-regulating kinase 1 (ASK1), an inflammatory cytokine up-regulator that is responsible for reactive oxygen species (ROS), decreased methylmercury-induced TNF-α expression through decreased phosphorylation of p38 MAP kinase in BV2 cells. Suppression of methylmercury-induced reactive oxygen species (ROS) by antioxidant treatment largely abolished the induction of TNF-α expression and phosphorylation of p38 by methylmercury in BV2 cells. Finally, in mouse brain slices, the TNF-α antagonist (WP9QY) inhibited neuronal cell death induced by methylmercury, as did the p38 inhibitor SB203580 and liposomal clodronate (a microglia-depleting agent). These results indicate that methylmercury induces mitochondrial ROS that are involved in activation of the ASK1/p38 pathway in microglia and that this is associated with induction of TNF-α expression and neuronal cell death.

NFAT5-Mediated Signalling Pathways in Viral Infection and Cardiovascular Dysfunction

The nuclear factor of activated T cells 5 (NFAT5) is well known for its sensitivity to cellular osmolarity changes, such as in the kidney medulla. Accumulated evidence indicates that NFAT5 is also a sensitive factor to stress signals caused by non-hypertonic stimuli such as heat shock, biomechanical stretch stress, ischaemia, infection, etc. These osmolality-related and -unrelated stimuli can induce NFAT5 upregulation, activation and nuclear accumulation, leading to its protective role against various detrimental effects. However, dysregulation of NFAT5 expression may cause pathological conditions in different tissues, leading to a variety of diseases. These protective or pathogenic effects of NFAT5 are dictated by the regulation of its target gene expression and activation of its signalling pathways. Recent studies have found a number of kinases that participate in the phosphorylation/activation of NFAT5 and related signal proteins. Thus, this review will focus on the NFAT5-mediated signal transduction pathways. As for the stimuli that upregulate NFAT5, in addition to the stresses caused by hyperosmotic and non-hyperosmotic environments, other factors such as miRNA, long non-coding RNA, epigenetic modification and viral infection also play an important role in regulating NFAT5 expression; thus, the discussion in this regard is another focus of this review. As the heart, unlike the kidneys, is not normally exposed to hypertonic environments, studies on NFAT5-mediated cardiovascular diseases are just emerging and rapidly progressing. Therefore, we have also added a review on the progress made in this field of research.

Myostatin Promotes Osteoclastogenesis by Regulating Ccdc50 Gene Expression and RANKL-Induced NF-κB and MAPK Pathways

Myostatin is a crucial cytokine that is widely present in skeletal muscle and that negatively regulates the growth and development of muscle cells. Recent research has shown that myostatin might play an essential role in bone metabolism. In RAW264.7 cells and bone marrow monocytes (BMMCs), myostatin activates the expression of the II type receptor ActR II B. Here, we report that myostatin significantly promoted RANKL/M-CSF-induced osteoclastogenesis and activated NF-κB and MAPK pathways in vitro via the Ccdc50 gene. Overexpression of myostatin promoted osteoclastogenesis and osteoclastogenesis-related markers including c-Src, MMP9, CTR, CK, and NFATc1. Specifically, myostatin increased the phosphorylation of Smad2, which led to the activation of NF-κB and MAPK pathways to activate osteoclastogenesis. Ccdc50 was identified as a gene whose expression was highly decreased in osteoclastogenesis upon myostatin treatment, and it could inhibit the function of myostatin in osteoclastogenesis by blocking NF-κB and MAPKs pathways. Our study indicates that myostatin is a promising candidate target for inhibiting RANKL-mediated osteoclastogenesis and might participate in therapy for osteoporosis, and that the Ccdc50 gene plays a significant role in the regulatory process.

Novel PGK1 determines SKP2-dependent AR stability and reprograms granular cell glucose metabolism facilitating ovulation dysfunction

Background

Disordered folliculogenesis is a core characteristic of polycystic ovary syndrome (PCOS) and androgen receptors (ARs) are closely associated with hyperandrogenism and abnormalities in folliculogenesis in PCOS. However, whether the new AR binding partner phosphoglycerate kinase 1 (PGK1) in granulosa cells (GCs) plays a key role in the pathogenesis of PCOS remains unclear.

Methods

We identified the new AR binding partner PGK1 by co-IP (co-immunoprecipitation) in luteinized GCs, and reconfirmed by co-IP, co-localization and GST pull down assay, and checked PGK1 expression levels with qRT-PCR and western blotting. Pharmaceuticals rescue assays in mice, and metabolism assay, AR protein stability and RNA-seq of PGK1 targets in cells proved the function in PCOS.

Findings

PGK1 and AR are highly expressed in PCOS luteinized GCs and PCOS-like mouse ovarian tissues. PGK1 regulated glucose metabolism and deteriorated PCOS-like mouse metabolic disorder, and paclitaxel rescued the phenotype of PCOS-like mice and reduced ovarian PGK1 and AR protein levels. PGK1 inhibited AR ubiquitination levels and increased AR stability in an E3 ligase SKP2-dependent manner. Additionally, PGK1 promoted AR nuclear translocation, and RNA-seq data showed that critical ovulation-related genes were regulated by the PGK1-AR axis.

Interpretation

PGK1 regulated GCs metabolism and interacted with AR to regulate the expression of key ovulation genes, and also mediated cell proliferation and apoptosis, which resulted in the etiology of PCOS. This work highlights the pathogenic mechanism and represents a novel therapeutic target for PCOS.

Funding

National Key Research and Development Program of China; National Natural Science Foundation of China grant.

p38β and Cancer: The Beginning of the Road

The p38 mitogen-activated protein kinase (MAPK) signaling pathway is implicated in cancer biology and has been widely studied over the past two decades as a potential therapeutic target. Most of the biological and pathological implications of p38MAPK signaling are often associated with p38α (MAPK14). Recently, several members of the p38 family, including p38γ and p38δ, have been shown to play a crucial role in several pathologies including cancer. However, the specific role of p38β (MAPK11) in cancer is still elusive, and further investigation is needed. Here, we summarize what is currently known about the role of p38β in different types of tumors and its putative implication in cancer therapy. All evidence suggests that p38β might be a key player in cancer development, and could be an important therapeutic target in several pathologies, including cancer.

Gamma-irradiation-induced testicular oxidative stress and apoptosis: Mitigation by l-carnitine

The current study evaluated the potential ameliorative and protective impacts of l-carnitine (L-CAR) against γ-irradiation (RAD)-induced oxidative stress and apoptosis in mice testes. Male Swiss mice were allocated into four groups (n = 7). Group 1 served as a control that received saline intraperitoneally (IP). Group 2 received L-CAR (10 mg/kg bw/day; IP in saline) for 17 days. Group 3 received saline for 17 days and on day 7 exposed to RAD at a dose of 0.1 Gy per day for consecutive 10 days. Group 4 (L-CAR + RAD), received L-CAR same as in group 2 and on day 7 exposed to RAD for consecutive 10 days. Testicular antioxidants (malondialdehyde, MDA; γ-glutamyl-cysteine synthetase, gGCS; and catalase) were altered by γ-irradiation. Preadministration of L-CAR protected γ-irradiated mice from altered changes induced by γ-irradiation. γ-Irradiation affected the mRNA expression of pro-apoptotic, apoptotic, and anti-apoptotic genes (c-jun, c-fos, Bcl-xl, caspase-3, and BAX). All altered genes were ameliorated by prior l-carnitine administration to γ-irradiated mice. Testicular cells showed deformities and edema with congestion in seminiferous tubules and strong immunoreactivity for caspase-9 and a decrease in immunoreactivity of Bcl-2 in histological and immunohistochemical examination. Prior administration of L-CAR to γ-irradiated mice protected this group from reported changes in caspase-9 and Bcl-2 immunostaining. In conclusion, the current study provides evidence for the protective and ameliorative impacts of L-CAR against γ-irradiation-induced testicular oxidative stress and apoptosis at biochemical, molecular, and cellular levels.

An overview of mammalian p38 mitogen-activated protein kinases, central regulators of cell stress and receptor signaling

The p38 family is a highly evolutionarily conserved group of mitogen-activated protein kinases (MAPKs) that is involved in and helps co-ordinate cellular responses to nearly all stressful stimuli. This review provides a succinct summary of multiple aspects of the biology, role, and substrates of the mammalian family of p38 kinases. Since p38 activity is implicated in inflammatory and other diseases, we also discuss the clinical implications and pharmaceutical approaches to inhibit p38.

Regulation of the Expression of Heme Oxygenase-1: Signal Transduction, Gene Promoter Activation, and Beyond

Significance: Heme oxygenase-1 (HO-1) is a ubiquitous 32-kDa protein expressed in many tissues and highly inducible. They catalyze the degradation of the heme group and the release of free iron, carbon monoxide, and biliverdin; the latter converted to bilirubin by biliverdin reductase. Its role in the regulation of cellular homeostasis is widely documented. Studying regulation of HO-1 expression is important not only to understand the life of healthy cells but also the unbalances in cell metabolism that lead to disease. Recent Advances: The regulation of its enzymatic activity depends heavily upon changes in expression studied mainly at the transcriptional level. Current knowledge regarding HO-1 gene expression focuses primarily on transcription factors such as Nrf2 (nuclear factor erythroid 2-related factor 2), AP-1 (activator protein-1), and hypoxia-inducible factor, which collect signal transduction pathway information at the HO-1 gene promoter. Understanding of gene expression regulation is not limited to transcription factor activity but also involves an extended range of post- or cotranscriptional regulated events. Critical Issues: In addition to the regulation of gene promoter activity, alternative splicing, alternative polyadenylation, and regulation of messenger RNA stability play critical roles in changes in HO-1 gene expression levels, involving specific factors, proteins, and microRNAs. All potential targets for diagnosis or treatment of diseases are related to HO-1 dysregulation. Future Directions: Unbalances in the tightly regulated gene expression mechanisms lead to cell transformation and cancer development. Knowledge of these events and signal transduction cascades triggered by oncogenes in which HO-1 plays a critical role is of upmost importance for research in this field.

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.

Immunomodulatory effects of Rhipicephalus haemaphysaloides serpin RHS2 on host immune responses

Background

Rhipicephalus haemaphysaloides is a widespread tick species in China and other South East Asian countries, where it is the vector of many pathogens. The objective of this study was to study the role of serpin (serine protease inhibitor) during the tick-host interaction.

Methods

The differentiation of bone marrow-derived dendritic cells (BMDC) was induced in vitro, and the effect of RHS2 on the maturation of DCs was evaluated. The effects of RHS2 on T cell activation and cytotoxic T lymphocytes’ (CTLs) activity were analyzed by flow cytometry. Antibody subtypes after immunization of mice with RHS2 and OVA were determined.

Results

RHS2 can inhibit the differentiation of bone marrow-derived cells into DCs and promote their differentiation into macrophages. RHS2 can inhibit the maturation of DCs and the expression of CD80, CD86 and MHCII. The number of CD3⁺CD4⁺ and CD3⁺CD8⁺ T cells secreting IFN-γ, IL-2 and TNF-α was decreased, and the number of CD3⁺CD4⁺ T cells secreting IL-4 was increased, indicating that RHS2 can inhibit the activation of CD4 T cells and CD8 T cells, leading to inhibition of Th1 immune response. RHS2 inhibits the elimination of target cells by cytotoxic T lymphocytes. After immunization of mice with RHS2 and OVA, serum IgG2b was significantly reduced and IgM was increased.

Conclusions

The results show that RHS2 has an inhibitory effect on the host immune response. Ticks have evolved various ways to circumvent adaptive immunity. Their serpin inhibits BMDC differentiation to reduce immune responses.

The Novel p38 Inhibitor, Pamapimod, Inhibits Osteoclastogenesis and Counteracts Estrogen-Dependent Bone Loss in Mice

Pamapimod (PAM) is a novel selective p38 mitogen-activated protein (MAP) kinase inhibitor proved to be effective in rheumatoid arthritis in phase 2 clinical trial. However, its effect on osteoclast-associated osteoporosis and the underlying mechanisms remain unclear. In this study, we showed that PAM suppressed receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation via inhibition of p38 phosphorylation and subsequent c-Fos and nuclear factor of activated T cells c1 (NFATc1) expression. In addition, the downregulated NFATc1 leads to reduced expression of its targeting gene disintegrin and metalloproteinase domain-containing protein 12 (ADAM12), which was further proven to be critical for osteoclastic bone resorption. Therefore, we treated ovariectomized (OVX) mice with PAM and revealed a protective effect of PAM on osteoporosis in vivo. In conclusion, our results demonstrated PAM can prevent OVX-induced bone loss through suppression of p38/NFATc1-induced osteoclast formation and NFATc1/ADAM12-associated bone resorption. © 2018 American Society for Bone and Mineral Research.

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.

Melatonin attenuates the detrimental effects of UVA irradiation in human dermal fibroblasts by suppressing oxidative damage and MAPK/AP-1 signal pathway in vitro

BACKGROUND

People living in Mediterranean countries are mostly exposed to solar ultraviolet (UV) radiation that damages skin and results in photoaging which involves activation of epidermal growth factor receptor (EGFR) and downstream signal transduction through mitogen-activated protein kinases (MAPKs) in fibroblasts. Generation of reactive oxygen/nitrogen species by UV radiation is also critical for EGFR and MAPKs activation. MAPKs are responsible for activation of AP-1 subunits in the nucleus which induce matrix metalloproteinases. Melatonin, along with its metabolites, are known to be the most effective free radical scavenger and protective agent due to its ability to react with various radicals, lipophilic/hydrophilic structures.

OBJECTIVES

In this study, we investigated the effects of melatonin on UVA-irradiated primary human dermal fibroblasts (HDFs) by following the alteration of molecules from cell membrane to the nucleus and oxidative/nitrosative damage status of the cells in a time-dependent manner which have not been clearly elucidated yet.

METHODS

To mimic UVA dosage in Mediterranean countries, HDFs were exposed to UVA with sub-cytotoxic dosage (20 J/cm² ) after pretreatment with melatonin (1 μmol/L) for 1 hour. Changes in the activation of the molecules and oxidative/nitrosative stress damage were analyzed at different time points.

RESULTS

Our results clearly show that melatonin decreases UVA-induced oxidative/nitrosative stress damage in HDFs. It also suppresses phosphorylation of EGFR, activation of MAPK/AP-1 signal transduction pathway and production of matrix metalloproteinases in a time-dependent manner.

CONCLUSION

Melatonin can be used as a protective agent for skin damage against intracellular detrimental effects of relatively high dosage of UVA irradiation.

FOS, a Critical Downstream Mediator of PGR and EGF Signaling Necessary for Ovulatory Prostaglandins in the Human Ovary

CONTEXT

Fos null mice failed to ovulate and form a corpus luteum (CL) even when given exogenous gonadotropins, suggesting that ovarian Fos expression is critical for successful ovulation and CL formation. However, little is known about FOS in the human ovary.

OBJECTIVES

To determine the expression, regulation, and function of FOS in human periovulatory follicles.

DESIGN/PARTICIPANTS

Timed periovulatory follicles were obtained from normally cycling women. Granulosa/lutein cells were collected from in vitro fertilization patients.

MAIN OUTCOME MEASURES

The in vivo expression after human chorionic gonadotropin (hCG) administration and in vitro regulation of FOS, JUN, JUNB, and JUND was evaluated at the mRNA and protein level. Binding of progesterone receptor (PGR) and FOS to their target genes was assessed by chromatin immunoprecipitation analyses. Prostaglandin E2 (PGE2) and progesterone were measured.

RESULTS

The expression of FOS, JUNB, and JUND drastically increased in ovulatory follicles after hCG administration. In human granulosa/lutein cell cultures, hCG increased the expression of FOS and JUN proteins. Inhibitors of PGR and epidermal growth factor (EGF) receptors reduced hCG-induced increases in the expression and phosphorylation of FOS. PGR bound to the FOS gene. A selective FOS inhibitor blocked hCG-induced increases in PGE2 and the expression of prostaglandin (PG) synthases and transporters (PTGES, SLCO2A1, and ABCC1). FOS bound to the promoter regions of these genes.

CONCLUSIONS

The increase of FOS/activator protein 1 in human periovulatory follicles after hCG administration is mediated by collaborative actions of PGR and EGF signaling and critical for the upregulated expression of key ovulatory genes required for the rise in ovulatory PG in human granulosa cells.

Inhibition of Proteasome Activity Upregulates IL-6 Expression in RPE Cells through the Activation of P38 MAPKs

Purpose

As far as we know, during the development of age-related macular degeneration (AMD), the activity of proteasome in retinal pigment epithelium cells (RPE) gradually decreases. And a lot of research has shown that age-related macular degeneration is closely related to inflammation and autoimmune. Moreover, there are many cytokines (CKs) involved in the course of inflammation. In this study, we are going to investigate how the decrease of proteasome activity affects the production of interleukin-6 (IL-6) in human retinal pigment epithelium cells (ARPE-19).

Methods

Cultured ARPE-19 was treated with or without MG132, a proteasome inhibitor, and the levels of IL-6 mRNA (messenger ribonucleic acid) in RPE at 1 h, 4 h, 8 h, and IL-6 protein in the culture medium at 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h were measured by real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunosorbent assay (ELISA). The protein levels of MCP-1 (monocyte chemoattractant protein-1) in the culture medium at 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h were also measured by ELISA. Then we tested which of cell signal pathways regulating the production of IL-6 were activated when we added MG132 into the medium by Western blot and electrophoretic mobility shift assays (EMSA). After that, we put the inhibitors of these activated cell signal pathways into the medium individually to see which inhibitor can counteract the effect of upregulating the levels of IL-6 in the culture medium of RPE.

Results

MG132 decreased the secretion of MCP-1 in the culture medium of RPE, but it increased the expression of IL-6 mRNA in RPE and IL-6 protein level in the culture medium of RPE. MG132 treatment was also found to enhance the level of phosphorylated p38 mitogen-activated protein kinases (MAPKs) and c-Jun N-terminal Kinase (JNK) by Western blotting. More importantly, the effect of MG132 on upregulating the levels of IL-6 was inhibited by SB203580, an inhibitor of P38 MAP kinases. But the JNK inhibitor, SP600125, cannot prevent the effect of upregulating the levels of IL-6 by MG132 in the RPE culture medium.

Conclusions

We concluded that the proteasome inhibitor, MG132, upregulates IL-6 production in RPE cells through the activation of P38 MAPKs.

Prunella vulgaris L. Exerts a Protective Effect Against Extrinsic Aging Through NF-κB, MAPKs, AP-1, and TGF-β/Smad Signaling Pathways in UVB-Aged Normal Human Dermal Fibroblasts

Prunella vulgaris L., a well-known traditional Chinese herbal medicine, has anti-inflammatory and antioxidant activities. In the present study, the underlying molecular mechanisms of the protective effect of P. vulgaris extract (PVE) were investigated in UVB-irradiated normal human dermal fibroblasts (NHDFs). The mRNA expression of matrix metalloproteinases (MMPs), procollagen type I, and cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor (TNF-α), was determined by reverse transcription–polymerase chain reaction. The expression of anti-photoaging-related signaling molecules in the NF-κB, MAPK/AP-1, and TGF/Smad pathways was assessed by western blot. We observed that PVE blocked the upregulated production of radical oxygen species induced in UVB-irradiated NHDFs in a dose-dependent manner. Treatment with PVE also significantly ameliorated the mRNA levels of MMPs, procollagen type I, TNF-α, and IL-6. In addition, the phosphorylation level of c-Jun and c-Fos was decreased through the attenuated expression levels of p-ERK and p-JNK after treatment with PVE. Furthermore, cells treated with PVE showed inhibited Smad 7 and increased Smad 2/3 expression in the TGF-β/Smad signaling pathway. Hence, synthesis of procollagen type I, a precursor of collagen I, was promoted. These findings indicate that treatment with PVE has a potential protective effect against UVB-induced photoaging and photoinflammation.

p38 and JNK pathways control E-selectin-dependent extravasation of colon cancer cells by modulating miR-31 transcription

Extravasation of circulating cancer cells is a key event of metastatic dissemination that is initiated by the adhesion of cancer cells to vascular endothelial cells. It requires the interaction between adhesion receptors such as E-selectin present on endothelial cells and their ligands on cancer cells. Notably, E-selectin influences the metastatic potential of breast, bladder, gastric, pancreatic, and colorectal carcinoma as well as of leukemia and lymphoma. Here, we show that E-selectin expression induced by the pro-inflammatory cytokine IL-1β is directly and negatively regulated by miR-31. The transcription of miR-31 is activated by IL-1β. This activation depends on p38 and JNK MAP kinases, and their downstream transcription factors GATA2, c-Fos and c-Jun. The miR-31-mediated repression of E-selectin impairs the metastatic potential of colon cancer cells by decreasing their adhesion to, and migration through, the endothelium. These results highlight for the first time that microRNA mediates E-selectin-dependent extravasation of colon cancer cells.

Troxerutin down-regulates KIM-1, modulates p38 MAPK signaling, and enhances renal regenerative capacity in a rat model of gentamycin-induced acute kidney injury

Troxerutin enhances renal tissue regeneration, improves renal function, and decreases renal tissue injury in gentamycin-treated rats.

Photoaging protective effects of BIOGF1K, a compound-K-rich fraction prepared from Panax ginseng

BACKGROUND

BIOGF1K, a compound-K-rich fraction, has been shown to display anti-inflammatory activity. Although Panax ginseng is widely used for the prevention of photoaging events induced by UVB irradiation, the effect of BIOGF1K on photoaging has not yet been examined. In this study, we investigated the effects of BIOGF1K on UVB-induced photoaging events.

METHODS

We analyzed the ability of BIOGF1K to prevent UVB-induced apoptosis, enhance matrix metalloproteinase (MMP) expression, upregulate anti-inflammatory activity, reduce sirtuin 1 expression, and melanin production using reverse transcription-polymerase chain reaction, melanin content assay, tyrosinase assay, and flow cytometry. We also evaluated the effects of BIOGF1K on the activator protein-1 signaling pathway, which plays an important role in photoaging, by immunoblot analysis and luciferase reporter gene assays.

RESULTS

Treatment of UVB-irradiated NIH3T3 fibroblasts with BIOGF1K prevented UVB-induced cell death, inhibited apoptosis, suppressed morphological changes, reduced melanin secretion, restored the levels of type I procollagen and sirtuin 1, and prevented mRNA upregulation of MMP-1, MMP-2, and cyclo-oxygenase-2; these effects all occurred in a dose-dependent manner. In addition, BIOGF1K markedly reduced activator-protein-1-mediated luciferase activity and decreased the activity of mitogen-activated protein kinases (extracellular response kinase, p38, and C-Jun N-terminal kinase).

CONCLUSION

Our results strongly suggest that BIOGF1K has anti-photoaging activity and that BIOGF1K could be used in anti-aging cosmeceutical preparations.

Mechanosensing by the α6-integrin confers an invasive fibroblast phenotype and mediates lung fibrosis

Matrix stiffening is a prominent feature of pulmonary fibrosis. In this study, we demonstrate that matrix stiffness regulates the ability of fibrotic lung myofibroblasts to invade the basement membrane (BM). We identify α₆-integrin as a mechanosensing integrin subunit that mediates matrix stiffness-regulated myofibroblast invasion. Increasing α₆-expression, specifically the B isoform (α₆B), couples β₁-integrin to mediate MMP-2-dependent pericellular proteolysis of BM collagen IV, leading to myofibroblast invasion. Human idiopathic pulmonary fibrosis lung myofibroblasts express high levels of α₆-integrin in vitro and in vivo. Genetic ablation of α₆ in collagen-expressing mesenchymal cells or pharmacological blockade of matrix stiffness-regulated α₆-expression protects mice against bleomycin injury-induced experimental lung fibrosis. These findings suggest that α₆-integrin is a matrix stiffness-regulated mechanosensitive molecule which confers an invasive fibroblast phenotype and mediates experimental lung fibrosis. Targeting this mechanosensing α₆(β₁)-integrin offers a novel anti-fibrotic strategy against lung fibrosis.

Matrix stiffening is a feature of pulmonary fibrosis, and is amplified by lung myofibroblasts. Here the authors find that a6 integrin expression is upregulated on lung myofibroblasts in response to matrix stiffness, and this integrin is required for myofibroblast invasion, and fibrosis in an experimental disease model.

Type I interferons exert anti-tumor effect via reversing immunosuppression mediated by mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) are strongly immunosuppressive via producing nitric oxide (NO) and known to migrate into tumor sites to promote tumor growth, but the underlying mechanisms remain largely elusive. Here, we found that interferon alpha (IFNα)-secreting MSCs showed more dramatic inhibition effect on tumor progression than that of IFNα alone. Interestingly, IFNα-primed MSCs could also effectively suppress tumor growth. Mechanistically, we demonstrated that both IFNα and IFNβ (type I IFNs) reversed the immunosuppressive effect of MSCs on splenocyte proliferation. This effect of type I IFNs was exerted through inhibiting inducible NO synthase (iNOS) expression in IFNγ and TNFα-stimulated MSCs. Notably, only NO production was inhibited by IFNα production of other cytokines or chemokines tested was not suppressed. Furthermore, IFNα promoted the switch from signal transducer and activator of transcription 1 (Stat1) homodimers to Stat1-Stat2 heterodimers. Studies using the luciferase reporter system and chromatin immunoprecipitation assay revealed that IFNα suppressed iNOS transcription through inhibiting the binding of Stat1 to iNOS promoter. Therefore, the synergistic anti-tumor effects of type I IFNs and MSCs were achieved by inhibiting NO production. This study provides essential information for understanding the mechanisms of MSC-mediated immunosuppression and for the development of better clinical strategies using IFNs and MSCs for cancer immunotherapy.

Transcription Factors in the Cellular Response to Charged Particle Exposure

Charged particles, such as carbon ions, bear the promise of a more effective cancer therapy. In human spaceflight, exposure to charged particles represents an important risk factor for chronic and late effects such as cancer. Biological effects elicited by charged particle exposure depend on their characteristics, e.g., on linear energy transfer (LET). For diverse outcomes (cell death, mutation, transformation, and cell-cycle arrest), an LET dependency of the effect size was observed. These outcomes result from activation of a complex network of signaling pathways in the DNA damage response, which result in cell-protective (DNA repair and cell-cycle arrest) or cell-destructive (cell death) reactions. Triggering of these pathways converges among others in the activation of transcription factors, such as p53, nuclear factor κB (NF-κB), activated protein 1 (AP-1), nuclear erythroid-derived 2-related factor 2 (Nrf2), and cAMP responsive element binding protein (CREB). Depending on dose, radiation quality, and tissue, p53 induces apoptosis or cell-cycle arrest. In low LET radiation therapy, p53 mutations are often associated with therapy resistance, while the outcome of carbon ion therapy seems to be independent of the tumor's p53 status. NF-κB is a central transcription factor in the immune system and exhibits pro-survival effects. Both p53 and NF-κB are activated after ionizing radiation exposure in an ataxia telangiectasia mutated (ATM)-dependent manner. The NF-κB activation was shown to strongly depend on charged particles' LET, with a maximal activation in the LET range of 90-300 keV/μm. AP-1 controls proliferation, senescence, differentiation, and apoptosis. Nrf2 can induce cellular antioxidant defense systems, CREB might also be involved in survival responses. The extent of activation of these transcription factors by charged particles and their interaction in the cellular radiation response greatly influences the destiny of the irradiated and also neighboring cells in the bystander effect.

Dynamic regulation of aquaporin-4 water channels in neurological disorders

Aquaporin-4 water channels play a central role in brain water regulation in neurological disorders. Aquaporin-4 is abundantly expressed at the astroglial endfeet facing the cerebral vasculature and the pial membrane, and both its expression level and subcellular localization significantly influence brain water transport. However, measurements of aquaporin-4 levels in animal models of brain injury often report opposite trends of change at the injury core and the penumbra. Furthermore, aquaporin-4 channels play a beneficial role in brain water clearance in vasogenic edema, but a detrimental role in cytotoxic edema and exacerbate cell swelling. In light of current evidence, we still do not have a complete understanding of the role of aquaporin-4 in brain water transport. In this review, we propose that the regulatory mechanisms of aquaporin-4 at the transcriptional, translational, and post-translational levels jointly regulate water permeability in the short and long time scale after injury. Furthermore, in order to understand why aquaporin-4 channels play opposing roles in cytotoxic and vasogenic edema, we discuss experimental evidence on the dynamically changing osmotic gradients between blood, extracellular space, and the cytosol during the formation of cytotoxic and vasogenic edema. We conclude with an emerging picture of the distinct osmotic environments in cytotoxic and vasogenic edema, and propose that the directions of aquaporin-4-mediated water clearance in these two types of edema are distinct. The difference in water clearance pathways may provide an explanation for the conflicting observations of the roles of aquaporin-4 in edema resolution.

Differential Expression of the Activator Protein 1 Transcription Factor Regulates Interleukin-1ß Induction of Interleukin 6 in the Developing Enterocyte

The innate immune response is characterized by activation of transcription factors, nuclear factor kappa B and activator protein-1 and their downstream targets, the pro-inflammatory cytokines including interleukin 1β and interleukin 6. Normal development of this response in the intestine is critical to survival of the human neonate and delays can cause the onset of devastating inflammatory diseases such as necrotizing enterocolitis. Previous studies have addressed the role of nuclear factor kappa B in the development of the innate immune response in the enterocyte, however despite its central role in the control of multiple pro-inflammatory cytokine genes, little is known on the role of Activator Protein 1 in this response in the enterocyte. Here we show that the canonical Activator Protein 1 members, cJun and cFos and their upstream kinases JNK and p38 play an essential role in the regulation of interleukin 6 in the immature enterocyte. Our data supports a model whereby the cFos/cJun heterodimer and the more potent cJun homodimer downstream of JNK are replaced by less efficient JunD containing dimers, contributing to the decreased responsiveness to interleukin 1β and decreased interleukin 6 secretion observed in the mature enterocyte. The tissue specific expression of JunB in colonocytes and colon derived tissues together with its ability to repress Interleukin-1β induction of an Interleukin-6 gene reporter in the NCM-460 colonocyte suggests that induction of JunB containing dimers may offer an attractive therapeutic strategy for the control of IL-6 secretion during inflammatory episodes in this area of the intestine

Dynamics of chromatin accessibility and epigenetic state in response to UV damage

Epigenetic mechanisms determine the access of regulatory factors to DNA during events such as transcription and the DNA damage response. However, the global response of histone modifications and chromatin accessibility to UV exposure remains poorly understood. Here, we report that UV exposure results in a genome-wide reduction in chromatin accessibility, while the distribution of the active regulatory mark H3K27ac undergoes massive reorganization. Genomic loci subjected to epigenetic reprogramming upon UV exposure represent target sites for sequence-specific transcription factors. Most of these are distal regulatory regions, highlighting their importance in the cellular response to UV exposure. Furthermore, UV exposure results in an extensive reorganization of super-enhancers, accompanied by expression changes of associated genes, which may in part contribute to the stress response. Taken together, our study provides the first comprehensive resource for genome-wide chromatin changes upon UV irradiation in relation to gene expression and elucidates new aspects of this relationship.

Vigilant keratinocytes trigger pathogen-associated molecular pattern signaling in response to streptococcal M1 protein

The human skin exerts many functions in order to maintain its barrier integrity and protect the host from invading microorganisms. One such pathogen is Streptococcus pyogenes, which can cause a variety of superficial skin wounds that may eventually progress into invasive deep soft tissue infections. Here we show that keratinocytes recognize soluble M1 protein, a streptococcal virulence factor, as a pathogen-associated molecular pattern to release alarming inflammatory responses. We found that this interaction initiates an inflammatory intracellular signaling cascade involving the activation of the mitogen-activated protein kinases extracellular signal-regulated kinase (ERK), p38, and Jun N-terminal protein kinase and the subsequent induction and mobilization of the transcription factors NF-κB and AP-1. We also determined the imprint of the inflammatory mediators released, such as interleukin-8 (IL-8), growth-related oncogene alpha, migration inhibitory factor, extracellular matrix metalloproteinase inducer, IL-1α, IL-1 receptor a, and ST2, in response to streptococcal M1 protein. The expression of IL-8 is dependent on Toll-like receptor 2 activity and subsequent activation of the mitogen-activated protein kinases ERK and p38. Notably, this signaling seems to be distinct for IL-8 release, and it is not shared with the other inflammatory mediators. We conclude that keratinocytes participate in a proinflammatory manner in streptococcal pattern recognition and that expression of the chemoattractant IL-8 by keratinocytes constitutes an important protective mechanism against streptococcal M1 protein.