LncRNA SOX2-OT regulates AKT/ERK and SOX2/GLI-1 expression, hinders therapy, and worsens clinical prognosis in malignant lung diseases.

The involvement of LncRNA SOX2-overlapping transcript (SOX2-OT), SOX2, and GLI-1 transcription factors in cancer has been well documented. Nonetheless, it is still unknown whether co-expressed SOX2-OT/SOX2 or SOX2-OT/SOX2/GLI-1 axes are epigenetically/transcriptionally involved in terms of resistance to oncology therapy and in poorer clinical outcomes for patients with lung cancer. We evaluated the role of SOX2-OT/SOX2 and SOX2-OT/SOX2/GLI-1 axes using RT-qPCR, western blot, immunofluorescence analyses, gene silencing, cellular cytotoxic, and ChIP-qPCR assays on human cell lines, solid lung malignant tumors, and normal lung tissue. We detected that the SOX2-OT/SOX2/GLI-1 axis promotes resistance to tyrosine kinase inhibitor (TKI)-erlotinib and cisplatin-based therapy. Evidence from this study show that SOX2-OT modulates the expression/activation of EGFR-pathway members AKT/ERK. Further, both SOX2-OT and GLI-1 genes are epigenetically regulated at their promoter sequences, in an LncRNA SOX2-OT-dependent manner, mainly through modifying the enrichment of the activation histone mark H3K4me3/H3K27Ac, versus the repressive histone mark H3K9me3/H3K27me3. In addition, we identified that inhibition of SOX2-OT and reduced expression of SOX2/GLI-1 sensitizes lung cancer cells to EGFR/TKI-erlotinib or cisplatin-based treatment. Finally, we show that high co-expression of SOX2-OT/SOX2 transcripts and SOX2/GLI-1 proteins appears to correlate with a poor clinical prognosis and lung malignant phenotype. Collectively, these results present evidence that LncRNA SOX2-OT modulates an orchestrated resistance mechanism, promoting poor prognosis and human lung malignancy through genetic, epigenetic, and post-translational mechanisms.

Interaction network of proteins associated with unfavorable prognosis in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a malignant disorder of hematopoietic stem and progenitor cells, characterized by accumulation of immature blasts in the bone marrow and peripheral blood of affected patients. Standard induction therapy leads to complete remission in approximately 50% to 75% of patients. In spite of favorable primary response rates, only 20% to 30% of patients enjoy long-term disease free survival. Identifying proteins involved in prognosis is important for proposing biomarkers that can aid in the clinical management of the disease. The aim of this study was to construct a protein-protein interaction (PPI) network based on serum proteins associated with unfavorable prognosis of AML, and analyze the biological pathways underlying molecular complexes in the network. We identified 16 candidate serum proteins associated with unfavorable prognosis (in terms of poor response to treatment, poor overall survival, short complete remission, and relapse) in AML via a search in the literature: IL2RA, FTL, HSP90AA1, D2HGDH, PLAU, COL18A1, FGF19, SPP1, FGA, PF4, NME1, TNF, ANGPT2, B2M, CD274, LGALS3. The PPI network was constructed with Cytoscape using association networks from String and BioGRID, and Gene Ontology enrichment analysis using the ClueGo pluggin was performed. The central protein in the network was found to be PTPN11 which is involved in modulating the RAS-ERK, PI3K-AKT and JAK-STAT pathways, as well as in hematopoiesis, and in the regulation of apoptotic genes. Therefore, a dysregulation of this protein and/or of the proteins connected to it in the network leads to the defective activation of these signaling pathways and to a reduction in apoptosis. Together, this could cause an increase in the frequency of leukemic cells and a resistance to apoptosis in response to treatment.

Extracellular-Signal Regulated Kinase: A Central Molecule Driving Epithelial-Mesenchymal Transition in Cancer.

Epithelial-mesenchymal transition (EMT) is a reversible cellular process, characterized by changes in gene expression and activation of proteins, favoring the trans-differentiation of the epithelial phenotype to a mesenchymal phenotype. This process increases cell migration and invasion of tumor cells, progression of the cell cycle, and resistance to apoptosis and chemotherapy, all of which support tumor progression. One of the signaling pathways involved in tumor progression is the MAPK pathway. Within this family, the ERK subfamily of proteins is known for its contributions to EMT. The ERK subfamily is divided into typical (ERK 1/2/5), and atypical (ERK 3/4/7/8) members. These kinases are overexpressed and hyperactive in various types of cancer. They regulate diverse cellular processes such as proliferation, migration, metastasis, resistance to chemotherapy, and EMT. In this context, in vitro and in vivo assays, as well as studies in human patients, have shown that ERK favors the expression, function, and subcellular relocalization of various proteins that regulate EMT, thus promoting tumor progression. In this review, we discuss the mechanistic roles of the ERK subfamily members in EMT and tumor progression in diverse biological systems.

Polysome Profiling of a Human Glioblastoma Reveals Intratumoral Heterogeneity.

Glioblastoma (GBM) is one of the most aggressive cancers, with median survival of less than 2 years. Despite of considerable advance in molecular classification of GBMs, no improvements in therapy have been described. The scenario is further complicated by tumor heterogeneity and the relationship among genetic, transcriptional and functional findings. Classically, gene expression has been evaluated by steady-state mRNA, however, this does not take translational control into consideration, which contributes considerably to the composition of the proteome. In this study, we evaluated the transcriptomic and translatomic signature of a GBM obtained from a single patient focusing in tumor heterogeneity. In a sampling of eight fragments, we investigated the translation rates, mTORC1 and ERK1/2 pathways and identified both total and polysome associated mRNAs. An increased translation rate was observed in fragments with high-grade histological features. High-grade histology was also associated with the expression of genes related to extracellular matrix (ECM) and angiogenesis, in both transcriptomes and translatomes. However, genes associated with epithelial to mesenchymal transition and stress response, were observed only in translatomes from high-grade fragments. Overall, our results demonstrate that isolation of translated mRNA can be used to identify biomarkers and reveal previously unrecognized determinants of heterogeneity in GBMs.

Expression differences of genes in the PI3K/AKT, WNT/b-catenin, SHH, NOTCH and MAPK signaling pathways in CD34+ hematopoietic cells obtained from chronic phase patients with chronic myeloid leukemia and from healthy controls.

PURPOSE: The fusion gene BCR-ABL has an important role to the progression of chronic myeloid leukemia (CML) and several signaling pathways have been characterized as responsible for the terminal blastic phase (BP). However, the initial phase, the chronic phase (CP), is long lasting and there is much yet to be understood about the critical role of BCR-ABL in this phase. This study aims to evaluate transcriptional deregulation in CD34+ hematopoietic cells (CD34+ cells) from patients with untreated newly diagnosed CML compared with CD34+HC from healthy controls. METHODS: Gene expression profiling in CML-CD34 cells and CD34 cells from healthy controls were used for this purpose with emphasis on five main pathways important for enhanced proliferation/survival, enhanced self-renewal and block of myeloid differentiation. RESULTS: We found 835 genes with changed expression levels (fold change ≥ ±2) in CML-CD34 cells compared with CD34 cells. These include genes belonging to PI3K/AKT, WNT/b-catenin, SHH, NOTCH and MAPK signaling pathways. Four of these pathways converge to MYC activation. We also identified five transcripts upregulated in CD34-CML patients named OSBPL9, MEK2, p90RSK, TCF4 and FZD7 that can be potential biomarkers in CD34-CML-CP. CONCLUSION: We show several mRNAs up- or downregulated in CD34-CML during the chronic phase.

c-Jun integrates signals from both MEK/ERK and MKK/JNK pathways upon vaccinia virus infection.

Usurpation of the host's signalling pathways is a common strategy employed by viruses to promote their successful replication. Here we show that infection with the orthopoxvirus vaccinia virus (VACV) leads to sustained stimulation of c-Jun activity during the entire infective cycle. This stimulation is temporally regulated through MEK/ERK or MKK/JNK pathways, i.e. during the early/mid phase (1 to 6 hpi) and in the late phase (9 to 24 hpi) of the infective cycle, respectively. As a transcriptional regulator, upon infection with VACV, c-Jun is translocated from the cytoplasm to the nucleus, where it binds to the AP-1 DNA sequence found at the promoter region of its target genes. To investigate the role played by c-Jun during VACV replication cycle, we generated cell lines that stably express a c-Jun-dominant negative (DNc-Jun) mutation. Our data revealed that c-Jun is required during early infection to assist with viral DNA replication, as demonstrated by the decreased amount of viral DNA found in the DNc-Jun cells. We also demonstrated that c-Jun regulates the expression of the early growth response gene (egr-1), a gene previously shown to affect VACV replication mediated by MEK/ERK signalling. VACV-induced stimulation of the MKK/JNK/JUN pathway impacts viral dissemination, as we observed a significant reduction in both viral yield, during late stages of infection, and virus plaque size. Collectively, our data suggest that, by modulating the host's signalling pathways through a common target such as c-Jun, VACV temporally regulates its infective cycle in order to successfully replicate and subsequently spread.

Attenuation of epidermal growth factor (EGF) signaling by growth hormone (GH).

Transgenic mice overexpressing growth hormone (GH) show increased hepatic protein content of the epidermal growth factor receptor (EGFR), which is broadly associated with cell proliferation and oncogenesis. However, chronically elevated levels of GH result in desensitization of STAT-mediated EGF signal and similar response of ERK1/2 and AKT signaling to EGF compared to normal mice. To ascertain the mechanisms involved in GH attenuation of EGF signaling and the consequences on cell cycle promotion, phosphorylation of signaling mediators was studied at different time points after EGF stimulation, and induction of proteins involved in cell cycle progression was assessed in normal and GH-overexpressing transgenic mice. Results from kinetic studies confirmed the absence of STAT3 and 5 activation and comparable levels of ERK1/2 phosphorylation upon EGF stimulation, which was associated with diminished or similar induction of c-MYC, c-FOS, c-JUN, CYCLIN D1 and CYCLIN E in transgenic compared to normal mice. Accordingly, kinetics of EGF-induced c-SRC and EGFR phosphorylation at activating residues demonstrated that activation of these proteins was lower in the transgenic mice with respect to normal animals. In turn, EGFR phosphorylation at serine 1046/1047, which is implicated in the negative regulation of the receptor, was increased in the liver of GH-overexpressing transgenic mice both in basal conditions and upon EGF stimulus. Increased basal phosphorylation and activation of the p38-mitogen-activated protein kinase might account for increased Ser 1046/1047 EGFR. Hyperphosphorylation of EGFR at serine residues would represent a compensatory mechanism triggered by chronically elevated levels of GH to mitigate the proliferative response induced by EGF.

Quinolinic acid neurotoxicity: Differential roles of astrocytes and microglia via FGF-2-mediated signaling in redox-linked cytoskeletal changes.

QUIN is a glutamate agonist playing a role in the misregulation of the cytoskeleton, which is associated with neurodegeneration in rats. In this study, we focused on microglial activation, FGF2/Erk signaling, gap junctions (GJs), inflammatory parameters and redox imbalance acting on cytoskeletal dynamics of the in QUIN-treated neural cells of rat striatum. FGF-2/Erk signaling was not altered in QUIN-treated primary astrocytes or neurons, however cytoskeleton was disrupted. In co-cultured astrocytes and neurons, QUIN-activated FGF2/Erk signaling prevented the cytoskeleton from remodeling. In mixed cultures (astrocyte, neuron, microglia), QUIN-induced FGF-2 increased level failed to activate Erk and promoted cytoskeletal destabilization. The effects of QUIN in mixed cultures involved redox imbalance upstream of Erk activation. Decreased connexin 43 (Cx43) immunocontent and functional GJs, was also coincident with disruption of the cytoskeleton in primary astrocytes and mixed cultures. We postulate that in interacting astrocytes and neurons the cytoskeleton is preserved against the insult of QUIN by activation of FGF-2/Erk signaling and proper cell-cell interaction through GJs. In mixed cultures, the FGF-2/Erk signaling is blocked by the redox imbalance associated with microglial activation and disturbed cell communication, disrupting the cytoskeleton. Thus, QUIN signal activates differential mechanisms that could stabilize or destabilize the cytoskeleton of striatal astrocytes and neurons in culture, and glial cells play a pivotal role in these responses preserving or disrupting a combination of signaling pathways and cell-cell interactions. Taken together, our findings shed light into the complex role of the active interaction of astrocytes, neurons and microglia in the neurotoxicity of QUIN.

Inhibition of subcutaneously implanted human pituitary tumor cells in nude mice by LRIG1.

The aim of this study was to explore the inhibition of subcutaneously implanted human pituitary tumor cells in nude mice by LRIG1 and its mechanism. For this study, athymic nude mice were injected with either normal pituitary tumor RC-4B/C cells or LRIG1-transfected RC-4B/C cells. We then calculated the volume inhibition rate of the tumors, as well as the apoptosis index of tumor cells and the expression of Ras, Raf, AKt, and ERK mRNA in tumor cells. Tumor cell morphological and structural changes were also observed under electron microscope. Our data showed that subcutaneous tumor growth was slowed or even halted in LRIG1-transfected tumors. The tumor volumes were significantly different between the two groups of mice (χ2 = 2.14, P < 0.05). The tumor apoptosis index was found to be 8.72% in the control group and 39.7% in LRIG1-transfected mice (χ2 = 7.59, P < 0.05). The levels of Ras, Raf, and AKt mRNA in LRIG1-transfected RC-4B/C cells were significantly reduced after transfection (P < 0.01). Transfected subcutaneous tumor cells appeared to be in early or late apoptosis under an electron microscope, while only a few subcutaneous tumor cells appeared to be undergoing apoptosis in the control group. In conclusion, the LRIG1 gene is able to inhibit proliferation and promote apoptosis in subcutaneously implanted human pituitary tumors in nude mice. The mechanism of LRIG1 may involve the inhibition of the PI3K/ Akt and Ras/Raf/ERK signal transduction pathways.

Impact and significance of EGCG on Smad, ERK, and ß-catenin pathways in transdifferentiation of renal tubular epithelial cells.

We investigated the impact and signal transduction mechanisms of epigallocatechin-3-gallate (EGCG) on transdiffer-entiation of renal tubular epithelial cells. Rat renal tubular epithelial cells (NRK-52E) were randomly divided into a normal control group, transforming growth factor (TGF)-b1-induced group (10 ng/mL), and intervention groups with 200 mg/L EGCG + 10 ng/mL TGF-b1 and 400 mg/L EGCG + 10 ng/mL TGF-b1. Tested cells were collected after 48 h. Levels of a-smooth muscle actin (α-SMA) and cytokeratin-18 were detected using immunohistochemical methods. Western blotting was used to detect cytoplasmic Pi-extracellular receptor kinase 1/2 (ERK1/2), Pi-Smad3 protein, and nuclear b-catenin protein. mRNA expression of ERK2, Smad3, and ß-catenin was measured by reverse transcription-polymerase chain reaction. After induction by TGF-b1, cytokeratin-18 expression in the renal tubular epithelial cells decreased and a-SMA expression appeared. mRNA expression of cytoplasmic Pi-Smad3 and Pi-ERK1/2, Smad3, ERK2, and b-catenin protein expression increased, while ß-catenin mRNA decreased. These changes were reduced after intervention by EGCG. EGCG may be helpful for maintaining the renal tubular epithelial cell phenotype and reducing the degree of TGF-b1- induced cell transdifferentiation, which may be related to the signal transduction pathway of ERK, Smad3, and ß-catenin.

Leishmania mexicana lipophosphoglycan activates ERK and p38 MAP kinase and induces production of proinflammatory cytokines in human macrophages through TLR2 and TLR4.

Protozoan parasites of genus Leishmania are the causative agents of leishmaniasis. Leishmania promastigotes primarily infect macrophages in the host, where they transform into amastigotes and multiply. Lipophosphoglycan (LPG), the most abundant surface molecule of the parasite, is a virulence determinant that regulates the host immune response. Promastigotes are able to modulate this effect through LPG, creating a favourable environment for parasite survival, although the mechanisms underlying this modulation remain unknown. We analysed the participation of TLR2 and TLR4 in the production of cytokines and explored the possible phosphorylation of ERK and/or p38 MAP kinase signalling cascades in human macrophages stimulated with Leishmania mexicana LPG. The results show that LPG induced the production of TNF-α, IL-1ß, IL-12p40, IL-12p70 and IL-10 and led to phosphorylation of ERK and p38 MAP kinase. Specific inhibitors of ERK or p38 MAP kinases and mAbs against TLR2 and TLR4 reduced cytokine production and phosphorylation of both kinases. Our results suggest that L. mexicana LPG binds TLR2 and TLR4 receptors in human macrophages, leading to ERK and MAP kinase phosphorylation and production of pro-inflammatory cytokines.

Prophylactic systemic P2X7 receptor blockade prevents experimental colitis.

BACKGROUND: The P2X7 receptor (P2X7-R) is a non-selective adenosine triphosphate-gated cation channel present in epithelial and immune cells, and involved in inflammatory response. Extracellular nucleotides released in conditions of cell stress or inflammation may function as a danger signal alerting the immune system from inflammation. We investigated the therapeutic action of P2X7-R blockade in a model of inflammatory bowel disease. METHODS: Rats with trinitrobenzene sulfonic (TNBS) acid-induced colitis were treated with the P2X7-R antagonists A740003 or brilliant blue G (BBG) through intra-peritoneal (IP) or intra-colonic (IC) injection prior to colitis induction. Clinical and endoscopic follow-up, histological scores, myeloperoxidase activity, densities of collagen fibers and goblet cells were evaluated. P2X7-R expression, NF-kappa B and Erk activities, and densities of T-cells and macrophages were analyzed by immunoperoxidase. The inflammatory response was determined by measuring inflammatory cytokines in cultures of colon explants, by enzyme-linked immunosorbent assay. Colonic apoptosis was determined by the TUNEL assay. RESULTS: IP-BBG significantly attenuated the severity of colitis, myeloperoxidase activity, collagen deposition, densities of lamina propria T-cells and macrophages, while maintaining goblet cell densities. IP-BBG inhibited the increase in P2X7-R expression in parallel with apoptotic rates. TNF-α and interleukin-1ß stabilized in low levels, while TGF-ß and interleukin-10 did not change following IP-BBG-therapy. Colonic NF-kappa-B and Erk activation were significantly lower in IP-BBG-treated animals. Prophylactic IP-A740003 also protected rats against the development of TNBS-colitis. CONCLUSIONS: Prophylactic systemic P2X7-R blockade is effective in the prevention of experimental colitis, probably due to a systemic anti-inflammatory action, interfering with a stress-inflammation amplification loop mediated by P2X7-R.

17ß-estradiol protects mitochondrial functions through extracellular-signal-regulated kinase in C2C12 muscle cells.

BACKGROUND/AIMS: We have previously shown that exposure to 17ß-estradiol (E2) prior to induction of apoptosis with H2O2 protects skeletal muscle cells against oxidative damage. However, the mechanism involved in the protective action of the hormone is poorly understood. In the present study, we focused on the mechanism by which ERK mediates this survival effect in connection with COXIV activity and mitochondrial membrane potential. METHODS: Immunocytochemistry, Western blot, cytochrome c oxidase complex IV (COXIV) activity, coimmunoprecipitation and JC-1 dye by flow cytometry were carried out using C2C12 myoblasts as experimental model. RESULTS: E2 is able to activate ERK and then induces its translocation to mitochondria. Using the pharmacological inhibitor of ERK activation U0126 we show that E2, through ERK activation, is able to enhance COXIV activity. Moreover, the hormone increases the interaction between COXIV and ERK. Also, we found that hydrogen peroxide decreases COXIV activity and that preincubation of the cells with E2 prior to induction of apoptosis prevents this effect. In addition, we observe that the estrogen inhibits the collapse of mitochondrial membrane potential induced by H2O2, involving ERK and COXIV. CONCLUSION: Our data demonstrate that E2 promotes ERK activation and translocation to mitochondria preventing the decline in COXIV activity and in turn, alteration of mitochondrial membrane potential by oxidative stress, in C2C12 myoblasts.

Tegumentary manifestations of Noonan and Noonan-related syndromes.

OBJECTIVES: Noonan and Noonan-related syndromes are common autosomal dominant disorders with neuro-cardio-facial-cutaneous and developmental involvement. The objective of this article is to describe the most relevant tegumentary findings in a cohort of 41 patients with Noonan or Noonan-related syndromes and to detail certain aspects of the molecular mechanisms underlying ectodermal involvement. METHODS: A standard questionnaire was administered. A focused physical examination and a systematic review of clinical records was performed on all patients to verify the presence of tegumentary alterations. The molecular analysis of this cohort included sequencing of the following genes in all patients: PTPN1, SOS1, RAF1, KRAS, SHOC2 and BRAF. RESULTS: The most frequent tegumentary alterations were xeroderma (46%), photosensitivity (29%), excessive hair loss (24%), recurrent oral ulcers (22%), curly hair (20%), nevi (17%), markedly increased palmar and plantar creases (12%), follicular hyperkeratosis (12%), palmoplantar hyperkeratosis (10%), café-au-lait spots (10%) and sparse eyebrows (7%). Patients with mutations in PTPN11 had lower frequencies of palmar and plantar creases and palmar/plantar hyperkeratosis compared with the other patients. CONCLUSIONS: We observed that patients with mutations in genes directly involved in cell proliferation kinase cascades (SOS1, BRAF, KRAS and RAF1) had a higher frequency of hyperkeratotic lesions compared with patients with mutations in genes that have a more complex interaction with and modulation of cell proliferation kinase cascades (PTPN11).

Tegumentary manifestations of Noonan and Noonan-related syndromes

OBJECTIVES: Noonan and Noonan-related syndromes are common autosomal dominant disorders with neuro-cardio-facial-cutaneous and developmental involvement. The objective of this article is to describe the most relevant tegumentary findings in a cohort of 41 patients with Noonan or Noonan-related syndromes and to detail certain aspects of the molecular mechanisms underlying ectodermal involvement. METHODS: A standard questionnaire was administered. A focused physical examination and a systematic review of clinical records was performed on all patients to verify the presence of tegumentary alterations. The molecular analysis of this cohort included sequencing of the following genes in all patients: PTPN1, SOS1, RAF1, KRAS, SHOC2 and BRAF. RESULTS: The most frequent tegumentary alterations were xeroderma (46%), photosensitivity (29%), excessive hair loss (24%), recurrent oral ulcers (22%), curly hair (20%), nevi (17%), markedly increased palmar and plantar creases (12%), follicular hyperkeratosis (12%), palmoplantar hyperkeratosis (10%), café-au-lait spots (10%) and sparse eyebrows (7%). Patients with mutations in PTPN11 had lower frequencies of palmar and plantar creases and palmar/plantar hyperkeratosis compared with the other patients. CONCLUSIONS: We observed that patients with mutations in genes directly involved in cell proliferation kinase cascades (SOS1, BRAF, KRAS and RAF1) had a higher frequency of hyperkeratotic lesions compared with patients with mutations in genes that have a more complex interaction with and modulation of cell proliferation kinase cascades (PTPN11). .

Identification and pathway analysis of microRNAs with no previous involvement in breast cancer.

microRNA expression signatures can differentiate normal and breast cancer tissues and can define specific clinico-pathological phenotypes in breast tumors. In order to further evaluate the microRNA expression profile in breast cancer, we analyzed the expression of 667 microRNAs in 29 tumors and 21 adjacent normal tissues using TaqMan Low-density arrays. 130 miRNAs showed significant differential expression (adjusted P value = 0.05, Fold Change = 2) in breast tumors compared to the normal adjacent tissue. Importantly, the role of 43 of these microRNAs has not been previously reported in breast cancer, including several evolutionary conserved microRNA*, showing similar expression rates to that of their corresponding leading strand. The expression of 14 microRNAs was replicated in an independent set of 55 tumors. Bioinformatic analysis of mRNA targets of the altered miRNAs, identified oncogenes like ERBB2, YY1, several MAP kinases, and known tumor-suppressors like FOXA1 and SMAD4. Pathway analysis identified that some biological process which are important in breast carcinogenesis are affected by the altered microRNA expression, including signaling through MAP kinases and TP53 pathways, as well as biological processes like cell death and communication, focal adhesion and ERBB2-ERBB3 signaling. Our data identified the altered expression of several microRNAs whose aberrant expression might have an important impact on cancer-related cellular pathways and whose role in breast cancer has not been previously described.

17ß-Estradiol stimulates the translocation of endogenous estrogen receptor α at the plasma membrane of normal anterior pituitary cells.

In the present work we aimed at identifying ERα in the plasma membrane of normal anterior pituitary cells and investigated if 17ß-estradiol was able to induce their subcellular redistribution. Our results show that about 8% of anterior pituitary cells expressed ERα in the plasma membrane, with the geometrical mean fluorescence intensity being increased after steroid hormone treatment. 17ß-Estradiol and the selective ERα agonist PPT induced an increase of ERα expression in the plasma membrane and activated the PKCα/ERK 1/2 pathway in a time-course not compatible with genomic actions, thus supporting the notion of membrane-initiated effects. These findings suggest that 17ß-estradiol stimulates the translocation of endogenous ERα to the plasma membrane, consequently modulating this ER pool and leading to cellular biological effects in normal anterior pituitary gland.

Leukotrienes target F-actin/cofilin-1 to enhance alveolar macrophage anti-fungal activity.

Candida albicans is the most common opportunistic fungal pathogen and causes local and systemic disease in immunocompromised patients. Alveolar macrophages (AMs) are pivotal for the clearance of C. albicans from the lung. Activated AMs secrete 5-lipoxygenase-derived leukotrienes (LTs), which in turn enhance phagocytosis and microbicidal activity against a diverse array of pathogens. Our aim was to investigate the role of LTB(4) and LTD(4) in AM antimicrobial functions against C. albicans and the signaling pathways involved. Pharmacologic and genetic inhibition of LT biosynthesis as well as receptor antagonism reduced phagocytosis of C. albicans when compared with untreated or WT controls. Conversely, exogenous LTs of both classes augmented base-line C. albicans phagocytosis by AMs. Although LTB(4) enhanced mainly mannose receptor-dependent fungal ingestion, LTD(4) enhanced mainly dectin-1 receptor-mediated phagocytosis. LT enhancement of yeast ingestion was dependent on protein kinase C-δ (PKCδ) and PI3K but not PKCα and MAPK activation. Both LTs reduced activation of cofilin-1, whereas they enhanced total cellular F-actin; however, LTB(4) accomplished this through the activation of LIM kinases (LIMKs) 1 and 2, whereas LTD(4) did so exclusively via LIMK-2. Finally, both exogenous LTB(4) and LTD(4) enhanced AM fungicidal activity in an NADPH oxidase-dependent manner. Our data identify LTB(4) and LTD(4) as key mediators of innate immunity against C. albicans, which act by both distinct and conserved signaling mechanisms to enhance multiple antimicrobial functions of AMs.

Signal transduction pathways associated with ATP-induced proliferation of colon adenocarcinoma cells.

BACKGROUND: In previous work, we have demonstrated that extracellular adenosine 5'-triphosphate (ATP) acts on intestinal Caco-2 cell P2Y receptors promoting a rapid increase in the phosphorylation of ERK1/2, p46 JNK and p38 MAP kinases (MAPKs). METHODS AND RESULTS: In this study, we investigated whether the extracellular ATP-P2Y receptor signalling pathways were required for the proliferation of Caco-2 cells. Confocal microscopy and immunobloting studies showed that ERK1/2 and JNK translocate into the nucleus of the cells stimulated by ATP, where they participate, together with p38 MAPK, in the phosphorylation of JunD, ATF-1 and ATF-2 transcription factors. In addition, ATP through the activation of MAPKs induces the expression of the immediate early genes products of the Jun family, c-Fos and MAP kinase phosphatase-1 (MKP-1). Moreover, ERK1/2 and p38 MAPK are involved in the phosphorylation of MKP-1 in Caco-2 cells. Of physiological significance, in agreement with the mitogenic role of the MAPK cascade, ATP increased Caco-2 cell proliferation, and this effect was blocked by UO126, SB203580 and SP600125, the specific inhibitors of ERK1/2, p38 MAPK and JNK1/2, respectively. CONCLUSION: Extracellular ATP induces proliferation of Caco-2 human colonic cancer cells by activating MAPK cascades and modulation of transcription factors. GENERAL SIGNIFICANCE: These findings and identification of the specific P2Y subtype receptors involved in the mitogenic effect of ATP on Caco-2 cells might be relevant for understanding tumor cell development, resistance to treatment regimens and the design of new therapeutic strategies.

Extracellular-regulated kinase and p38 mitogen-activated protein kinases are involved in the antiapoptotic action of 17beta-estradiol in skeletal muscle cells.

17beta-Estradiol (E(2)) stimulates the mitogen-activated protein kinases (MAPKs) in various cellular types. We have shown that the hormone activates extracellular-regulated kinase (ERK) and p38 MAPK in skeletal muscle cells. However, the functions of MAPK modulation by the estrogen in muscle cells have not been studied yet. We have recently reported antiapoptotic actions of E(2) in C2C12 cells. Here, the role of MAPKs mediating the hormone effect in muscle cells was investigated. The results showed that cells exposed to 0.5 mM hydrogen peroxide (H(2)O(2)) presented cytoskeleton disorganization, mitochondrial redistribution, and picnotic/fragmented nuclei. Pretreatment with 10(-8) M E(2) prevented these morphological apoptotic characteristics, except in the presence of ERK or p38 MAPK inhibitors, U0126 and SB203580 respectively. Mitochondrial membrane integrity was also studied. Preincubation of cultures with 10(-8) M E(2) abrogated H(2)O(2) effects such as Janus Green oxidation, presence of cytochrome c oxidase activity in the cytoplasm, and SMAC/DIABLO release from mitochondria. When MAPKs were inhibited, the hormone could not prevent mitochondrial membrane damage exerted by oxidative stress. Blocking experiments with small interfering RNAs confirmed that both ERK and p38 MAPKs mediate the antiapoptotic effects of the hormone at the mitochondrial level. Further, some of the molecular mechanisms involved were also investigated. Thus, E(2) was able to induce AKT (Ser473) and BAD (Ser112) phosphorylation in C2C12 cells in the absence or in the presence of H(2)O(2) but not when the cultures were incubated with H(2)O(2) and MAPK inhibitors. Altogether, these results show that E(2) exerts a survival action in skeletal muscle cells involving ERK and p38 MAPK activation.