BMP-1-induced GBA1 nuclear accumulation provokes CCN2 mRNA expression via importin-ß-mediated nucleocytoplasmic pathway.

Bone morphogenetic protein (BMP)-1 is expressed by odontoblasts in the dentin-pulp complex. Although the functional effects of BMP-1 on the maturation of various preforms of proteins and enzymes involved in initiating mineralization have been widely observed, how BMP-1 affects cellular molecules remains unknown. We performed a comprehensive analysis of BMP-1-altered glycome profiles and subsequent assays to identify the target glycoproteins in human dental pulp cells (hDPCs) by a glycomic approach. In the presence of BMP-1, a lectin microarray analysis and lectin-probed blotting showed that α2,6-sialylation was significantly attenuated in insoluble fractions from hDPCs. Six proteins were identified by a mass spectrometry analysis of α2,6-sialylated glycoproteins purified using a lectin column. Among them, glucosylceramidase (GBA1) was found to accumulate in the nuclei of hDPCs in the presence of BMP-1. Moreover, BMP-1-induced cellular communication network factor (CCN) 2 expression, which is well known as the osteogenesis/chondrogenesis marker, was significantly suppressed in the cells transfected with GBA1 siRNA. Furthermore, importazole, a potent inhibitor of importin-ß-mediated nuclear import significantly suppressed BMP-1-induced GBA1 nuclear accumulation and BMP-1-induced CCN2 mRNA expression, respectively. Thus, BMP-1 facilitates the accumulation of GBA1 in the nucleus through the reduction of α2,6-sialic acid, which potentially contributes to the transcriptional regulation of the CCN2 gene via importin-ß-mediated nuclear import pathway in hDPCs. Our results offer new insights into the role of the BMP-1-GBA1-CCN2 axis in the development, tissue remodeling, and pathology of dental/craniofacial diseases.

Interleukin-1ß triggers matrix metalloprotease-3 expression through p65/RelA activation in melanoma cells.

Melanoma shows highly aggressive behavior (i.e., local invasion and metastasis). Matrix metalloprotease-3 (MMP-3), a zinc-dependent endopeptidase, degrades several extracellular substrates and contributes to local invasion by creating a microenvironment suitable for tumor development. Here, we report that interleukin-1ß (IL-1ß) triggers the MMP-3 expression in canine melanoma cells. The activity of MMP-3 in the culture supernatant was increased in IL-1ß-treated melanoma cells. IL-1ß time- and dose-dependently provoked the mRNA expression of MMP-3. IL-1ß induced the migration of melanoma cells; however, this migration was attenuated by UK356618, an MMP-3 inhibitor. When the cells were treated with the nuclear factor-κB (NF-κB) inhibitor TPCA-1, the inhibition of MMP-3 expression was observed. In IL-1ß-treated cells, the phosphorylation both of p65/RelA and p105 was detected, indicating NF-κB pathway activation. In p65/RelA-depleted melanoma cells, IL-1ß-mediated mRNA expression of MMP-3 was inhibited, whereas this reduction was not observed in p105-depleted cells. These findings suggest that MMP-3 expression in melanoma cells is regulated through IL-1ß-mediated p65/RelA activation, which is involved in melanoma cell migration.

Canonical NF-κB p65, but Not p105, Contributes to IL-1ß-Induced IL-8 Expression in Cardiac Fibroblasts.

Cardiac fibroblasts participate in the inflammatory process of heart diseases as sentinel cells of the cardiac tissue. In this study, we investigated the effect of the proinflammatory cytokine, interleukin 1ß (IL-1ß), on the expression of interleukin 8 (IL-8), which contributes to the induction of innate immunity via the activation and recruitment of innate immune cells, such as neutrophils, to the site of inflammation in canine cardiac fibroblasts. IL-1ß mediates IL-8 mRNA expression and protein release in a dose- and time-dependent manner. The IL-ß-mediated IL-8 protein release and mRNA expression were inhibited by 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide, an inhibitor of the transcription factor, nuclear factor (NF)-κB. In cells treated with IL-1ß, NF-κB p65 and p105 were transiently phosphorylated, indicating the activation of NF-κB. However, IL-1ß failed to induce IL-8 mRNA expression in the cells transfected with p65 small interfering RNA (siRNA), but not in those transfected with p105 siRNA. These observations suggest that IL-1ß induces IL-8 expression via the activation of NF-κB p65 in canine cardiac fibroblasts.

Tpl2 contributes to IL-1ß-induced IL-8 expression via ERK1/2 activation in canine dermal fibroblasts.

In autoimmune diseases, fibroblasts produce and secrete various cytokines and act as sentinel immune cells during inflammatory states. However, the contribution of sentinel immune cells (i.e. dermal fibroblasts) in autoimmune diseases of the skin, such as atopic dermatitis, has been obscure. The pro-inflammatory cytokine interleukin 1ß (IL-1ß) induces the expression of chemokines, such as interleukin 8 (IL-8), in autoimmune diseases of the skin. IL-8 induces the activation and recruitment of innate immune cells such as neutrophils to the site of inflammation. IL-1ß-mediated induction of IL-8 expression is important for the pathogenesis of autoimmune diseases; however, the intracellular singling remains to be understood. To elucidate the mechanism of the onset of autoimmune diseases, we established a model for IL-1ß-induced dermatitis and investigated MAPK signaling pathways in IL-1ß-induced IL-8 expression. We also identified that a MAP3K Tpl2 acts as an upstream modulator of IL-1ß-induced ERK1/2 activation in dermal fibroblasts. We observed an increase in the expression of IL-8 mRNA and protein in cells treated with IL-1ß. ERK1/2 inhibitors significantly reduced IL-1ß-induced IL-8 expression, whereas the inhibitor for p38 MAPK or JNK had no effect. IL-1ß induced ERK1/2 phosphorylation, which was attenuated in the presence of an ERK1/2 inhibitor. IL-1ß failed to induce IL-8 expression in cells transfected with siRNA for ERK1, or ERK2. Notably, a Tpl2 inhibitor reduced IL-1ß-induced IL-8 expression and ERK1/2 phosphorylation. We confirmed that the silencing of Tpl2 in siRNA-transfected fibroblasts prevented both in IL-1ß-induced IL-8 expression and ERK1/2 phosphorylation. Taken together, our data indicate the importance of Tpl2 in the modulation of ERK1/2 signaling involved in the IL-1ß-induced development of autoimmune diseases affecting the dermal tissue, such as atopic dermatitis.

B cell-derived GABA elicits IL-10+ macrophages to limit anti-tumour immunity.

Small, soluble metabolites not only are essential intermediates in intracellular biochemical processes, but can also influence neighbouring cells when released into the extracellular milieu1-3. Here we identify the metabolite and neurotransmitter GABA as a candidate signalling molecule synthesized and secreted by activated B cells and plasma cells. We show that B cell-derived GABA promotes monocyte differentiation into anti-inflammatory macrophages that secrete interleukin-10 and inhibit CD8+ T cell killer function. In mice, B cell deficiency or B cell-specific inactivation of the GABA-generating enzyme GAD67 enhances anti-tumour responses. Our study reveals that, in addition to cytokines and membrane proteins, small metabolites derived from B-lineage cells have immunoregulatory functions, which may be pharmaceutical targets allowing fine-tuning of immune responses.

Decoding Neuronal Diversification by Multiplexed Single-cell RNA-Seq.

Cellular reprogramming is driven by a defined set of transcription factors; however, the regulatory logic that underlies cell-type specification and diversification remains elusive. Single-cell RNA-seq provides unprecedented coverage to measure dynamic molecular changes at the single-cell resolution. Here, we multiplex and ectopically express 20 pro-neuronal transcription factors in human dermal fibroblasts and demonstrate a widespread diversification of neurons based on cell morphology and canonical neuronal marker expressions. Single-cell RNA-seq analysis reveals diverse and distinct neuronal subtypes, including reprogramming processes that strongly correlate with the developing brain. Gene mapping of 20 exogenous pro-neuronal transcription factors further unveiled key determinants responsible for neuronal lineage specification and a regulatory logic dictating neuronal diversification, including glutamatergic and cholinergic neurons. The multiplex scRNA-seq approach is a robust and scalable approach to elucidate lineage and cellular specification across various biological systems.

Involvement of GLUT1 and GLUT3 in the growth of canine melanoma cells.

The rate of glucose uptake dramatically increases in cancer cells even in the presence of oxygen and fully functioning mitochondria. Cancer cells produce ATP by glycolysis rather than oxidative phosphorylation under aerobic conditions, a process termed as the "Warburg effect." In the present study, we treated canine melanoma cells with the glucose analog 2-deoxy-D-glucose (2-DG) and investigated its effect on cell growth. 2-DG attenuated cell growth in a time- and dose-dependent manner. Cell growth was also inhibited following treatment with the glucose transporter (GLUT) inhibitor WZB-117. The treatment of 2-DG and WZB-117 attenuated the glucose consumption, lactate secretion and glucose uptake of the cells. The mRNA expression of the subtypes of GLUT was examined and GLUT1 and GLUT3 were found to be expressed in melanoma cells. The growth, glucose consumption and lactate secretion of melanoma cells transfected with siRNAs of specific for GLUT1 and GLUT3 was suppressed. These findings suggest that glucose uptake via GLUT1 and GLUT3 plays a crucial role for the growth of canine melanoma cells.

Author Correction: Aberrant expression of the COX2/PGE2 axis is induced by activation of the RAF/MEK/ERK pathway in BRAFV595E canine urothelial carcinoma.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Non-Transcriptional and Translational Function of Canonical NF-κB Signaling in Activating ERK1/2 in IL-1ß-Induced COX-2 Expression in Synovial Fibroblasts.

The pro-inflammatory cytokine interleukin 1ß (IL-1ß) induces the synthesis of prostaglandin E2 by upregulating cyclooxygenase-2 (COX-2) in the synovial tissue of individuals with autoimmune diseases, such as rheumatoid arthritis (RA). IL-1ß-mediated stimulation of NF-κB and MAPK signaling is important for the pathogenesis of RA; however, crosstalk(s) between NF-κB and MAPK signaling remains to be understood. In this study, we established a model for IL-1ß-induced synovitis and investigated the role of NF-κB and MAPK signaling in synovitis. We observed an increase in the mRNA and protein levels of COX-2 and prostaglandin E2 release in cells treated with IL-1ß. NF-κB and ERK1/2 inhibitors significantly reduced IL-1ß-induced COX-2 expression. IL-1ß induced the phosphorylation of canonical NF-κB complex (p65 and p105) and degradation of IκBα. IL-1ß also induced ERK1/2 phosphorylation but did not affect the phosphorylation levels of p38 MAPK and JNK. IL-1ß failed to induce COX-2 expression in cells transfected with siRNA for p65, p105, ERK1, or ERK2. Notably, NF-κB inhibitors reduced IL-1ß-induced ERK1/2 phosphorylation; however, the ERK1/2 inhibitor had no effect on the phosphorylation of the canonical NF-κB complex. Although transcription and translation inhibitors had no effect on IL-1ß-induced ERK1/2 phosphorylation, the silencing of canonical NF-κB complex in siRNA-transfected fibroblasts prevented IL-1ß-induced phosphorylation of ERK1/2. Taken together, our data indicate the importance of the non-transcriptional/translational activity of canonical NF-κB in the activation of ERK1/2 signaling involved in the IL-1ß-induced development of autoimmune diseases affecting the synovial tissue, such as RA.

Biological Properties of JNK3 and Its Function in Neurons, Astrocytes, Pancreatic ß-Cells and Cardiovascular Cells.

JNK is a protein kinase, which induces transactivation of c-jun. The three isoforms of JNK, JNK1, JNK2, and JNK3, are encoded by three distinct genes. JNK1 and JNK2 are expressed ubiquitously throughout the body. By contrast, the expression of JNK3 is limited and observed mainly in the brain, heart, and testes. Concerning the biological properties of JNKs, the contribution of upstream regulators and scaffold proteins plays an important role in the activation of JNKs. Since JNK signaling has been described as a form of stress-response signaling, the contribution of JNK3 to pathophysiological events, such as stress response or cell death including apoptosis, has been well studied. However, JNK3 also regulates the physiological functions of neurons and non-neuronal cells, such as development, regeneration, and differentiation/reprogramming. In this review, we shed light on the physiological functions of JNK3. In addition, we summarize recent advances in the knowledge regarding interactions between JNK3 and cellular reprogramming.

Aberrant expression of the COX2/PGE2 axis is induced by activation of the RAF/MEK/ERK pathway in BRAFV595E canine urothelial carcinoma.

Cancer-promoting inflammation is an important event in cancer development. Canine urothelial carcinoma (cUC) overexpresses prostaglandin E2 (PGE2) and has a unique sensitivity to cyclooxygenase 2 (COX2)-inhibiting therapy. In addition, majority of cUC harbour BRAFV595E mutation. However, mechanisms underlying aberrant PGE2 production in BRAFV595E cUC patients remain unclear. Drug screening revealed that inhibition of RAF/MEK/ERK pathway, p38 and JNK pathway reduced PGE2 production in cUC cells. By pharmacological inhibition of the multiple components in the pathway, activation of the ERK MAPK pathway was shown to mediate overexpression of COX2 and production of PGE2 in BRAFV595E cUC cells. In silico gain-of-function analysis of the BRAF mutation also implicated involvement of mutation in the process. The positive association between ERK activation and COX2 expression was further validated in the clinical patients. Moreover, it was also suggested that p38 and JNK regulates PGE2 production independently of ERK pathway, possibly through COX2-dependent and COX1-/COX2- independent manner, respectively. In conclusion, this study demonstrated that activation of ERK induces production of PGE2 in BRAFV595E cUC cells, which is also independently regulated by p38 and JNK. With its unique vulnerability to COX-targeted therapy, BRAFV595E cUC may serve as a valuable model to study the tumour-promoting inflammation.

All-trans retinoic acid induces reprogramming of canine dedifferentiated cells into neuron-like cells.

The specification of cell identity depends on the exposure of cells to sequences of bioactive ligands. All-trans retinoic acid (ATRA) affects neuronal development in the early stage, and it is involved in neuronal lineage reprogramming. We previously established a fibroblast-like dedifferentiated fat cells (DFATs) derived from highly homogeneous mature adipocytes, which are more suitable for the study of cellular reprogramming. Canine cognitive dysfunction is similar to human cognitive dysfunction, suggesting that dogs could be a pathological and pharmacological model for human neuronal diseases. However, the effect of ATRA on neuronal reprogramming in dogs has remained unclear. Therefore, in this study, we investigated the effect of ATRA on the neuronal reprogramming of canine DFATs. ATRA induced the expression of neuronal marker mRNA/protein. The neuron-like cells showed Ca2+ influx with depolarization (50 mM KCl; 84.75 ± 4.05%) and Na+ channel activation (50 µM veratridine; 96.02 ± 2.02%). Optical imaging of presynaptic terminal activity and detection of neurotransmitter release showed that the neuron-like cells exhibited the GABAergic neuronal property. Genome-wide RNA-sequencing analysis shows that the transcriptome profile of canine DFATs is effectively reprogrammed towards that of cortical interneuron lineage. Collectively, ATRA can produce functional GABAergic cortical interneuron-like cells from canine DFATs, exhibiting neuronal function with > 80% efficiency. We further demonstrated the contribution of JNK3 to ATRA-induced neuronal reprogramming in canine DFATs. In conclusion, the neuron-like cells from canine DFATs could be a powerful tool for translational research in cell transplantation therapy, in vitro disease modeling, and drug screening for neuronal diseases.

ERK1/ATF-2 signaling axis contributes to interleukin-1ß-induced MMP-3 expression in dermal fibroblasts.

Matrix metalloproteinases (MMPs) play a pivotal role in tissue remodeling by degrading the extracellular matrix (ECM) components. This mechanism is implicated in a variety of physiological and pathological cellular processes including wound healing. One of the key proteins involved in this process is the proinflammatory cytokine interleukin-1ß (IL-1ß, which induces the expression of MMP-3 mRNA and the secretion of MMP-3 protein by dermal fibroblasts. In this study, we first investigated the contribution of activating transcription factor 2 (ATF-2) to IL-1ß-induced MMP-3 expression in dermal fibroblasts. Our results showed that in cells transfected with ATF-2 siRNA or treated with the ATF-2 inhibitor SBI-0087702, IL-1ß-induced MMP-3 mRNA expression was reduced. We also demonstrated that IL-1ß stimulates the phosphorylation of ATF-2. These observations suggest that ATF-2 plays an important role in IL-1ß-induced MMP-3 expression. Next, we investigated the role of MAPK signaling in ATF-2 activation. In cells treated with the extracellular signal-regulated kinase (ERK) inhibitor FR180240, as well as in cells transfected with ERK1 and ERK2 siRNAs, IL-1ß-induced MMP-3 mRNA expression was reduced. In addition, we showed that IL-1ß induced the phosphorylation of ERK1/2. These observations suggest that ERK1 and ERK2 are involved in IL-1ß-induced MMP-3 expression. However, ERK1 and ERK2 do seem to play different roles. While the ERK inhibitor FR180204 inhibited IL-1ß-induced ATF-2 phosphorylation, only in cells transfected with ERK1 siRNA, but not ERK2 siRNA, IL-1ß-induced ATF-2 phosphorylation was reduced. These findings suggest that the ERK1/ATF-2 signaling axis contributes to IL-1ß-induced MMP-3 expression in dermal fibroblasts.

Interleukin-1ß promotes interleulin-6 expression via ERK1/2 signaling pathway in canine dermal fibroblasts.

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in the regulation of the immune response and inflammation. In this study, we investigated effect of the proinflammatory cytokine interleukin-1ß (IL-1ß) on IL-6 expression in canine dermal fibroblasts. IL-1ß induced IL-6 mRNA expression and protein release in a time- and dose-dependent manner. When cells were treated with inhibitors of mitogen-activated protein kinases (MAPKs), the extracellular signal-regulated kinase (ERK) inhibitor FR180240 inhibited IL-1ß-induced IL-6 mRNA expression, but not SP600125 or SKF86002, which are c-Jun N-terminal kinase (JNK) and p38 MAPK inhibitors, respectively. In cells treated with U0126, an inhibitor of MAPK/ERK kinase (MEK), which activates ERK, IL-1ß-induced IL-6 mRNA expression was also inhibited. IL-1ß stimulated ERK1/2 phosphorylation. In cells transfected with ERK1 and ERK2 isoform siRNAs, IL-1ß-induced IL-6 mRNA expression was reduced. These observations suggest that IL-1ß induces IL-6 expression via ERK1/2 signaling pathway in canine dermal fibroblasts.

NF-κB p65 and p105 implicate in interleukin 1ß-mediated COX-2 expression in melanoma cells.

Inflammatory and microenvironmental factors produced by cancer cells are thought to directly or indirectly promote cancer cell growth. Prostaglandins, including prostaglandin E2, have key roles as a microenvironment factor in influencing the development of tumors, and are produced by the rate limiting enzyme cyclooxygenase 2 (COX-2). In this study, we used canine melanoma cells treated with the proinflammatory cytokine interleukin 1ß (IL-1ß) and investigated the transcriptional factor nuclear factor-κB (NF-κB) signaling in IL-1ß-induced COX-2 expression. IL-1ß induced prostaglandin E2 release and COX-2 mRNA expression in a time- and dose-dependent manner. In the cells treated with the NF-κB inhibitors BAY11-7082 and TPC-1, IL-1ß-mediated prostaglandin E2 release and COX-2 mRNA expression were inhibited. IL-1ß also provoked phosphorylation of p65/RelA and p105/NF-κB1, which are members of the NF-κB families. The IL-1ß-induced phosphorylation of p65 and p105 was attenuated in the presence of both NF-κB inhibitors. In melanoma cells transfected with siRNA of p65 or p105, IL-1ß-mediated COX-2 mRNA expression was inhibited. These findings suggest that canonical activation of NF-κB signaling plays a crucial role for inflammatory states in melanoma cells.

Protein kinase Cε regulates nuclear translocation of extracellular signal-regulated kinase, which contributes to bradykinin-induced cyclooxygenase-2 expression.

The proinflammatory mediator bradykinin stimulated cyclooxygenase-2 (COX-2) expression and subsequently prostaglandin E2 synthesis in dermal fibroblasts. The involvement of B2 receptors and Gαq in the role of bradykinin was suggested by using pharmacological inhibitors. The PKC activator PMA stimulated COX-2 mRNA expression. Bradykinin failed to induce COX-2 mRNA expression in the presence of PKC inhibitors, whereas the effect of bradykinin was observed in the absence of extracellular Ca2+. Bradykinin-induced COX-2 mRNA expression was inhibited in cells transfected with PKCε siRNA. These observations suggest that the novel PKCε is concerned with bradykinin-induced COX-2 expression. Bradykinin-induced PKCε phosphorylation and COX-2 mRNA expression were inhibited by an inhibitor of 3-phosphoinositide-dependent protein kinase-1 (PDK-1), and bradykinin-induced PDK-1 phosphorylation was inhibited by phospholipase D (PLD) inhibitors, suggesting that PLD/PDK-1 pathway contributes to bradykinin-induced PKCε activation. Pharmacological and knockdown studies suggest that the extracellular signal-regulated kinase 1 (ERK1) MAPK signaling is involved in bradykinin-induced COX-2 expression. Bradykinin-induced ERK phosphorylation was attenuated in the cells pretreated with PKC inhibitors or transfected with PKCε siRNA. We observed the interaction between PKCε and ERK by co-immunoprecipitation experiments. These observations suggest that PKCε activation contributes to the regulation of ERK1 activation. Bradykinin stimulated the accumulation of phosphorylated ERK in the nuclear fraction, that was inhibited in the cells treated with PKC inhibitors or transfected with PKCε siRNA. Consequently, we concluded that bradykinin activates PKCε via the PLD/PDK-1 pathway, which subsequently induces activation and translocation of ERK1 into the nucleus, and contributes to COX-2 expression for prostaglandin E2 synthesis in dermal fibroblasts.

ERK2 and JNK1 contribute to TNF-α-induced IL-8 expression in synovial fibroblasts.

Tumor necrosis factor α (TNF-α) induces the expression and secretion of interleukin 8 (IL-8), which contributes to synovitis in rheumatoid arthritis (RA). To elucidate the mechanism of the onset of RA, we used synovial fibroblasts without autoimmune inflammatory diseases and investigated MAPK signaling pathways in TNF-α-induced IL-8 expression. Synovial fibroblasts isolated from healthy dogs were characterized by flow cytometry, which were positive for the fibroblast markers CD29, CD44, and CD90 but negative for the hematopoietic cell markers CD14, CD34, CD45, and HLA-DR. TNF-α stimulated the secretion and mRNA expression of IL-8 in a time- and dose-dependent manner. ERK and JNK inhibitors attenuated TNF-α-induced IL-8 expression and secretion. TNF-α induced the phosphorylation of ERK1/2 and JNK1/2. TNF-α-induced IL-8 expression was attenuated both in ERK2- and JNK1-knockdown cells. TNF-α-induced ERK1/2 or JNK1/2 was observed in ERK2- or JNK1-knockdown cells, respectively, showing that there is no crosstalk between ERK2 and JNK1 pathways. These observations indicate that the individual activation of ERK2 and JNK1 pathways contributes to TNF-α-induced IL-8 expression in synovial fibroblasts, which appears to be involved in the progress in RA.

JNK activation is essential for activation of MEK/ERK signaling in IL-1ß-induced COX-2 expression in synovial fibroblasts.

The proinflammatory cytokine interleukin 1ß (IL-1ß) induces prostaglandin E2 (PGE2) production via upregulation of cyclooxygenase-2 (COX-2) expression in synovial fibroblasts. This effect of IL-1ß is involved in osteoarthritis. We investigated MAPK signaling pathways in IL-1ß-induced COX-2 expression in feline synovial fibroblasts. In the presence of MAPK inhibitors, IL-1ß-induced COX-2 expression and PGE2 release were both attenuated. IL-1ß induced the phosphorylation of p38, JNK, MEK, and ERK1/2. A JNK inhibitor prevented not only JNK phosphorylation but also MEK and ERK1/2 phosphorylation in IL-1ß-stimulated cells, but MEK and ERK1/2 inhibitors had no effect on JNK phosphorylation. A p38 inhibitor prevented p38 phosphorylation, but had no effect on MEK, ERK1/2, and JNK phosphorylation. MEK, ERK1/2, and JNK inhibitors had no effect on p38 phosphorylation. We also observed that in IL-1ß-treated cells, phosphorylated MEK, ERK1/2, and JNK were co-precipitated with anti-phospho-MEK, ERK1/2, and JNK antibodies. The silencing of JNK1 in siRNA-transfected fibroblasts prevented IL-1ß to induce phosphorylation of MEK and ERK1/2 and COX-2 mRNA expression. These observations suggest that JNK1 phosphorylation is necessary for the activation of the MEK/ERK1/2 pathway and the subsequent COX-2 expression for PGE2 release, and p38 independently contributes to the IL-1ß effect in synovial fibroblasts.

Expression and Function of Interleukin-1ß-Induced Neutrophil Gelatinase-Associated Lipocalin in Renal Tubular Cells.

Acute kidney injury (AKI) is characterized by a sudden loss of renal function. Early recognition of AKI, especially in critically ill patients, is essential for adequate therapy. Currently, neutrophil gelatinase-associated lipocalin (NGAL) is considered to be an effective biomarker of AKI; however, the regulation of its expression and function in renal tubular cells remains unclear. In this study, we investigated the regulation of the expression and function of NGAL in IL-1ß-treated Madin-Darby canine kidney (MDCK) cells as a model of renal tubular cells. IL-1ß induced a disturbance in the localization of E-cadherin and zonaoccludin-1 (ZO-1). The transepithelial electrical resistance (TER) also decreased 5 days after IL-1ß treatment. IL-1ß induced NGAL mRNA expression and protein secretion in a time- and dose-dependent manner, which occurred faster than the decrease in TER. In the presence of ERK1/2 and p38 inhibitors, IL-1ß-induced NGAL mRNA expression and protein secretion were significantly attenuated. In the presence of recombinant NGAL, IL-1ß-induced disturbance in the localization of E-cadherin and ZO-1 was attenuated, and the decrease in TER was partially maintained. These results suggest that NGAL can be used as a biomarker for AKI and that it functions as a protector from AKI.

Activation of MEK/ERK pathways through NF-κB activation is involved in interleukin-1ß-induced cyclooxygenease-2 expression in canine dermal fibroblasts.

The proinflammatory cytokine interleukin-1ß (IL-1ß) induced cyclooxygenases-2 (COX-2) mRNA expression and lipid mediator prostaglandin E2 release and in a time- and dose-dependent manner in canine dermal fibroblasts. The MEK inhibitor U0126 and the ERK inhibitor FR180204 clearly inhibited IL-1ß-induced prostaglandin E2 release and COX-2 mRNA expression. IL-1ß enhanced ERK1/2 phosphorylation, which was attenuated by inhibitors of MEK and ERK. The NF-κB inhibitor BAY 11-7082 also suppressed IL-1ß-induced prostaglandin E2 release and COX-2 mRNA expression. Treatment of fibroblasts with IL-1ß led to the phosphorylation of p65 and degradation of IκBα occurred, indicating that IL-1ß treatment activated NF-κB. MEK and ERK1/2 inhibitors had no effect on the phosphorylation of p65 subunit induced by IL-1ß, whereas the NF-κB inhibitor completely blocked IL-1ß-induced phosphorylation of ERK1/2. We also observed that IκBα-knockdown enhanced the phosphorylation of p65 and ERK1/2. These findings suggest that stimulation of MEK/ERK signaling pathway by NF-κB activation regulates IL-1ß-induced COX-2 expression and subsequent prostaglandin E2 release in canine dermal fibroblasts.