Major Signal Transduction Research Articles

Kinase activity profiling reveals active signal transduction pathways in pediatric acute lymphoblastic leukemia: a new approach for target discovery.

Still about 20% of patients with acute lymphoblastic leukemia (ALL) struggle with relapse, despite intensive chemotherapy. We and others have shown that kinase activity profiling is able to give more insights in active signal transduction pathways and point out interesting signaling hubs as well as new potential druggable targets. With this technique the gap between newly designed drugs and ALL may be bridged. The aim of this study was to perform kinome profiling on 20 pediatric ALL samples (14 BCP-ALL and six T-ALL) to identify signaling proteins relevant to ALL. We defined 250 peptides commonly activated in both BCP-ALL and T-ALL representing major signal transduction pathways including MAPK, PI3K/Akt, and regulators of the cell cycle/p53 pathway. For 27 peptides, differentially phosphorylation between BCP-ALL and T-ALL was observed. Among these, ten peptides were more highly phosphorylated in BCP-ALL while 17 peptides showed increased phosphorylation in T-ALL. Furthermore we selected one lead of the list of commonly activated peptides (HGFR_Y1235) in order to test its efficacy as a potential target and provide proof of principle for this approach. In conclusion kinome profiling is an elegant approach to study active signaling and identify interesting potential druggable targets.

Mir-146a and Mir-146b Regulate Human Dendritic Cell Apoptosis and Cytokine Production By Targeting of TRAF6 and IRAK1

MicroRNA (miRNA) regulation of dendritic cell (DC) development and function is not fully understood. We have previously reported 27 differentially expressed miRNAs during human monocyte differentiation into immature DCs (imDCs) and mature DCs (mDCs). Here, we aimed at uncovering the functional role of miR-146a and miR-146b (miR-146a/b) during this differentiation process.To investigate miR-146a and miR-146b expression during human monocyte differentiation into imDCs and mDCs, monocytes were differentiated into imDCs with GM-CSF and IL-4 and matured with IL-1β, IL-6, TNF-α, and PGE2. We found by qRT-PCR that expression of miR-146a/b was dramatically increased upon monocyte differentiation into imDCs (miR-146a, 10-fold; miR-146b, 37-fold at day6; n=4; p value of Student t test<0.05) and mDCs (miR-146a, 51-fold; miR-146b, 79-fold; n=4; p<0.005). Up-regulation of miR-146a/b in mDCs was predominantly mediated by IL-1β but not IL-6, TNF-a, or PGE2 (n=3; p<0.01).DC apoptosis is important for self-tolerance and immunity. We then evaluated the effect of altering miR-146a/b expression levels on DC apoptosis by Annexin V/PI staining. Silencing of miR-146a, miR-146b or both in imDCs (Fig. 1A) and mDCs significantly prevented DC from apoptosis (Fig. 1A; miR-146a, 24%±3.1; miR-146b, 26%±1.7; miR-146a/b; 23%±2.8 vs control, 46%±2.3 of Annexin V+ populations; n=8; p<0.005) whereas overexpression of miR-146a, miR-146b or both in imDCs (Fig. 1B) and mDCs significantly increased the proportion of apoptotic cells (Fig. 1B; 46%±1.9, 47%±2.1, 45%±2.3 vs 36%±3.3; n=6; p<0.05). These results indicate that miR-146a/b may function as pro-apoptotic regulators during human monocyte differentiation into imDCs and mDCs.It is known that the NF-κB pathway regulates DC development, function and survival, and that TRAF6 and IRAK1 are major signal transducers in the NF-κB pathway. In addition, both TRAF6 and IRAK1 are known target genes of miR-146a. Indeed, miR-146a/b expression in imDCs and mDCs was inversely correlated with TRAF6 and IRAK1 mRNA and protein expression (n=4; p<0.05). Furthermore, siRNA silencing of TRAF6 and/or IRAK1 in imDCs and mDCs significantly enhanced DC apoptosis (n=4; p<0.05). By contrast, lentivirus overexpression of TRAF6 and/or IRAK1 promoted DC survival compared to control lentivirus transduced cells (n=2; p<0.05). To confirm that miR-146a/b-induced human DC apoptosis is involved in suppression of the NF-κB pathway, at least in part through down regulation of the NF-κB signaling transducers TRAF6 and IRAK1, we examined the protein level of IκB as a negative regulator of NF-κB and Bcl-2 as a known downstream anti-apoptotic molecule of the NF-κB pathway. Silencing of miR-146a/b in imDCs and mDCs significantly decreased IκBα and increased Bcl-2 expression whereas overexpression of miR-146a and/or miR-146b or silencing of TRAF6 and/or IRAK1 significantly increased IκBα and decreased Bcl-2 expression in imDCs and mDCs (n=4; p<0.01). These results indicate that miR-146a/b modulate DC apoptosis through inhibition of NF-κB activation via targeting TRAF6 and IRAK1.Next, we investigated whether miR-146a/b regulates pro-inflammatory cytokine production in DCs. We found that IL-12p70, IL-6 and TNF-α production were significantly enhanced after miR-146 and/or miR-146b silencing during DC maturation (n≥2; p<0.05), although altering miR-146a/b expression had little effect on DC maturation (n=6). By contrast, IL-12p70, IL-6 and TNF-α production was highly reduced after miR-146a and/or miR-146b overexpression (n≥2; p<0.05).In conclusion, we have demonstrated three important findings in this report. First, expression of both miR-146a and miR-146b is up-regulated during human monocyte differentiation into imDCs and mDCs. Secondly, although miR-146a and miR-146b do not appear to play a role in DC maturation, they may be critical regulators of DC apoptosis and cytokine production. Thirdly, mechanistically, miR-146a/b targets TRAF6 and IRAK1, leading to inhibition of NF-κB and reduced expression of Bcl-2. We thus demonstrate for the first time that miR-146a/b regulates human DC apoptosis and cytokine production, uncovering a new negative feedback mechanism for miR-146 in controlling overstimulation of the immune responses (Fig. 2). [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Novel Evidence That Pituitary Gonadotropins Directly Stimulate Human Leukemic cells—studies on Myeloid Cell Lines and Primary Patient AML and CML Cells

Background. It has been postulated that hematopoietic stem/progenitor cells (HSPCs) can become specified from a population of migrating primordial germ cells (PGCs) isolated from embryos. In support of this intriguing possibility, HSPCs and PGCs are both highly migratory populations of stem cells, and evidence has accumulated for the sharing of several mutated genes (e.g., Sall4) as well as chromosomal aberrations between germline tumors and leukemias or lymphomas, which suggests their common clonal origin. In fact, we recently observed that normal murine HSPCs express several functional receptors for pituitary gonadal hormones, such as follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL), in addition to gonadal hormones including estrogens, androgen, and progesterone. Of note, the plasma levels of FSH and LH are elevated in older patients, which correlate with an increase in the incidence of myeloid leukemia.Hypothesis. Based on this, we have hypothesized that gonadotropic hormones play a yet underappreciated role in human malignant hematopoiesis.Materials and Methods. To address this issue, we performed a complex series of experiments employing human myeloid hematopoietic cell lines (KG-1a, K-562, U937, THP-1, HEL) and primary patient cells (AML, CML) to address the influence of pituitary sex hormones (FSH, LH, PRL) as well as gonadal sex hormones (androgen, estrogen, progesterone) on proliferation, migration, and adhesion of malignant cells. In addition, expression of the corresponding receptors was evaluated at the mRNA level by PCR, and their functionality was confirmed by signaling studies based on phosphorylation of major signal transduction pathways (AKT, MAPKp42/44, STAT). Results. We demonstrate for the first time that human myeloid leukemia cell lines express all pituitary gonadotropin and several gonadal hormone receptors and that FSH and LH receptors are functional on these cells, as evaluated by chemotaxis and adhesion assays. Moreover, FSH and LH receptors were expressed and functional on patient leukemic blasts in bone marrow (BM) and peripheral blood (PB). Human leukemic cells from cell lines and primary patient-derived cells also expressed some other gonadal hormone receptors (PRL-R, estrogen, progesterone, and androgen receptors), albeit at lower levels. Moreover, we observed that several human myeloid cell lines as well as primary patient leukemic cells responded to sex hormones by proliferation.Conclusions. Our data are the first to indicate that pituitary-secreted gonadotropins stimulate migration, adhesion, and proliferation of leukemic cells. This latter effect seems to be direct, as the receptors for these hormones respond to stimulation by phosphorylation of intracellular pathways involved in cell proliferation. Established human myeloid leukemia cell lines and primary patient blasts also responded to stimulation by gonadal sex hormones. Finally, our studies provide further evidence supporting a developmental link between hematopoiesis and the germline. DisclosuresNo relevant conflicts of interest to declare.

P52 - Characterization of the NF-?B signaling triggered by doxorubicin

Doxorubicin (DOX) is an antibiotic used in the treatment of various cancers. However, its clinical use is limited due to the toxic effects it causes. In several biological systems reactive oxygen species (ROS) derived from DOX metabolism have been associated with its toxicity because they can alter several signal transduction pathways. One of the major signal transduction pathways activated in response to oxidant stress is that of the nuclear transcription factor ?B (NF-?B), which is crucial for cell survival, cell proliferation, and immune responses. Previous studies from our laboratory have described that DOX triggersthe activation of the MAPK (ERK, p38, and JNK) pathways, NF-?B mobilization and caspase activation in rat hepatocytes. These events were indirectly ascribed to ROS generation by pharmacological approaches. Although NF-?B mobilization is usually accompanied by up-regulation of the genes with regulatory ?B elements, our gene expression analysis rendered a quite different scenario. The aim of this work was to verify the implication of ROS in the DOX-mediated signaling and to explore the transcriptional regulatory behaviour of NF-?B mobilized by DOX. Results showed that DOX treatment induces ROS generation, particularly H2O2. DOX-induced caspase-3 activation was ROS dependent, whereas the NF-?B mobilization was a process independent of H2O2. Furthermore, DOX-mobilized NF-?B complexes were dimmers formed by p65 with all the members of the Rel family, excepting Rel B. The analysis of the NF-?B transcriptional activity performed by reporter gene assays suggests that these DOX-mobilized NF-?B complexes are not transcriptionally competent.

Inhibition of mitogen-activated protein kinase pathway can induce upregulation of human leukocyte antigen class I without PD-L1-upregulation in contrast to interferon-γ treatment.

Recently, we reported that human leukocyte antigen (HLA) class I expression is predominantly regulated by the mitogen-activated protein kinase (MAPK) pathway as one of the oncogenic regulations of HLA class I expression. In the present study, we examined mechanisms of how HLA class I and PD-L1 are regulated by MAPK inhibitors and interferon-γ (IFN-γ). Furthermore, we evaluated the expression of major signal transduction molecules by Western blot and anti-tumor CTL activity by a cytotoxic assay when HLA class I and PD-L1 were modulated by MAPK inhibitors and/or IFN-γ. As a result, we confirmed, as a more general phenomenon, that the inhibition of MAPK could upregulate HLA class I expression in a panel of human solid tumors (n = 26). Of note, we showed that MAPK inhibitors act on the upregulation of HLA class I expression through a different pathway from IFN-γ; there was an additive effect in the upregulation of HLA class I when treated with the combination of MAPK inhibitors and IFN-γ, and there was no overlapping activation of JAK2/STAT1 and Erk1/2 molecules when treated with either IFN-γ or MAPK inhibitors. Furthermore, we showed that IFN-γ–treatment impaired the tumor-specific CTL activity due to the upregulation of PD-L1 in spite of the upregulation of HLA class I, while MAPK inhibitors can augment the tumor-specific CTL activity due to the upregulated HLA class I without PD-L1 alterations. In conclusion, in addition to the original anti-proliferative activity, MAPK inhibitors may work toward the enhancement of T-cell-mediated anti-tumor immunity through the upregulation of HLA class I without the upregulation of PD-L1.

Quantitative phosphoproteomics of murine Fmr1-KO cell lines provides new insights into FMRP-dependent signal transduction mechanisms.

Fragile X mental retardation protein (FMRP) is an RNA-binding protein that has a major effect on neuronal protein synthesis. Transcriptional silencing of the FMR1 gene leads to loss of FMRP and development of Fragile X syndrome (FXS), the most common known hereditary cause of intellectual impairment and autism. Here we utilize SILAC-based quantitative phosphoproteomics to analyze murine FMR1(-) and FMR1(+) fibroblastic cell lines derived from FMR1-KO embryos to identify proteins and phosphorylation sites dysregulated as a consequence of FMRP loss. We quantify FMRP-related changes in the levels of 5,023 proteins and 6,133 phosphorylation events and map them onto major signal transduction pathways. Our study confirms global downregulation of the MAPK/ERK pathway and decrease in phosphorylation level of ERK1/2 in the absence of FMRP, which is connected to attenuation of long-term potentiation. We detect differential expression of several key proteins from the p53 pathway, pointing to the involvement of p53 signaling in dysregulated cell cycle control in FXS. Finally, we detect differential expression and phosphorylation of proteins involved in pre-mRNA processing and nuclear transport, as well as Wnt and calcium signaling, such as PLC, PKC, NFAT, and cPLA2. We postulate that calcium homeostasis is likely affected in molecular pathogenesis of FXS.

Sonic hedgehog signaling in Basal cell nevus syndrome.

The hedgehog (Hh) signaling pathway is considered to be a major signal transduction pathway during embryonic development, but it usually shuts down after birth. Aberrant Sonic hedgehog (Shh) activation during adulthood leads to neoplastic growth. Basal cell carcinoma (BCC) of the skin is driven by this pathway. Here, we summarize information related to the pathogenesis of this neoplasm, discuss pathways that crosstalk with Shh signaling, and the importance of the primary cilium in this neoplastic process. The identification of the basic/translational components of Shh signaling has led to the discovery of potential mechanism-driven druggable targets and subsequent clinical trials have confirmed their remarkable efficacy in treating BCCs, particularly in patients with nevoid BCC syndrome (NBCCS), an autosomal dominant disorder in which patients inherit a germline mutation in the tumor-suppressor gene Patched (Ptch). Patients with NBCCS develop dozens to hundreds of BCCs due to derepression of the downstream G-protein-coupled receptor Smoothened (SMO). Ptch mutations permit transposition of SMO to the primary cilium followed by enhanced expression of transcription factors Glis that drive cell proliferation and tumor growth. Clinical trials with the SMO inhibitor, vismodegib, showed remarkable efficacy in patients with NBCCS, which finally led to its FDA approval in 2012.

Investigation of olfactory function in a Panx1 knock out mouse model.

Pannexin 1 (Panx1), the most extensively investigated member of a channel-forming protein family, is able to form pores conducting molecules up to 1.5 kDa, like ATP, upon activation. In the olfactory epithelium (OE), ATP modulates olfactory responsiveness and plays a role in proliferation and differentiation of olfactory sensory neurons (OSNs). This process continuously takes place in the OE, as neurons are replaced throughout the whole lifespan. The recent discovery of Panx1 expression in the OE raises the question whether Panx1 mediates ATP release responsible for modulating chemosensory function. In this study, we analyzed pannexin expression in the OE and a possible role of Panx1 in olfactory function using a Panx1−/− mouse line with a global ablation of Panx1. This mouse model has been previously used to investigate Panx1 functions in the retina and adult hippocampus. Here, qPCR, in-situ hybridization, and immunohistochemistry (IHC) demonstrated that Panx1 is expressed in axon bundles deriving from sensory neurons of the OE. The localization, distribution, and expression of major olfactory signal transduction proteins were not significantly altered in Panx1−/− mice. Further, functional analysis of Panx1−/− animals does not reveal any major impairment in odor perception, indicated by electroolfactogram (EOG) measurements and behavioral testing. However, ATP release evoked by potassium gluconate application was reduced in Panx1−/− mice. This result is consistent with previous reports on ATP release in isolated erythrocytes and spinal or lumbar cord preparations from Panx1−/− mice, suggesting that Panx1 is one of several alternative pathways to release ATP in the olfactory system.

A medium-throughput analysis of signaling pathways involved in early stages of stem cell reprogramming.

The induction of pluripotency from adult cells has enormous potential in regenerative medicine. While initial efforts to study mechanisms and improve efficiency of induced pluripotent stem cell (iPSC) reprogramming focused on the direct roles of transcriptional regulators, increasing evidence indicates that cellular signal transduction pathways can modulate this process. Here, we present a medium-throughput system to study the effect of signaling pathways on the early stages of reprogramming. We generated a set of lentiviral vectors encoding 38 genes that upregulate or downregulate major signal transduction pathways and quantified each signaling factor's effect on reprogramming. This approach confirmed the role of several factors previously implicated in reprogramming, as well as identified several GTPases-factors that to date have not been largely studied in reprogramming-that improve or hinder iPSC reprogramming. In addition, this methodology is useful in determining new targets for enhancing pluripotency reprogramming, lineage reprogramming, and/or cell differentiation.

Aldehyde dehydrogenase 2 deficiency ameliorates alcoholic fatty liver but worsens liver inflammation and fibrosis in mice

Aldehyde dehydrogenase 2 (ALDH2) is the major enzyme that metabolizes acetaldehyde produced from alcohol metabolism. Approximately 40-50% of East Asians carry an inactive ALDH2 gene and exhibit acetaldehyde accumulation after alcohol consumption. However, the role of ALDH2 deficiency in the pathogenesis of alcoholic liver injury remains obscure. In the present study, wild-type and ALDH2(-/-) mice were subjected to ethanol feeding and/or carbon tetrachloride (CCl4 ) treatment, and liver injury was assessed. Compared with wild-type mice, ethanol-fed ALDH2(-/-) mice had higher levels of malondialdehyde-acetaldehyde (MAA) adduct and greater hepatic inflammation, with higher hepatic interleukin (IL)-6 expression but surprisingly lower levels of steatosis and serum alanine aminotransferase (ALT). Higher IL-6 levels were also detected in ethanol-treated precision-cut liver slices from ALDH2(-/-) mice and in Kupffer cells isolated from ethanol-fed ALDH2(-/-) mice than those levels in wild-type mice. In vitro incubation with MAA enhanced the lipopolysaccharide (LPS)-mediated stimulation of IL-6 production in Kupffer cells. In agreement with these findings, hepatic activation of the major IL-6 downstream signaling molecule signal transducer and activator of transcription 3 (STAT3) was higher in ethanol-fed ALDH2(-/-) mice than in wild-type mice. An additional deletion of hepatic STAT3 increased steatosis and hepatocellular damage in ALDH2(-/-) mice. Finally, ethanol-fed ALDH2(-/-) mice were more prone to CCl4 -induced liver inflammation and fibrosis than ethanol-fed wild-type mice. ALDH2(-/-) mice are resistant to ethanol-induced steatosis but prone to inflammation and fibrosis by way of MAA-mediated paracrine activation of IL-6 in Kupffer cells. These findings suggest that alcohol, by way of acetaldehyde and its associated adducts, stimulates hepatic inflammation and fibrosis independent from causing hepatocyte death, and that ALDH2-deficient individuals may be resistant to steatosis and blood ALT elevation, but are prone to liver inflammation and fibrosis following alcohol consumption.

Comparative proteomic analyses provide new insights into low phosphorus stress responses in maize leaves.

Phosphorus deficiency limits plant growth and development. To better understand the mechanisms behind how maize responds to phosphate stress, we compared the proteome analysis results of two groups of maize leaves that were treated separately with 1,000 µM (control, +P) and 5 µM of KH2PO4 (intervention group, −P) for 25 days. In total, 1,342 protein spots were detected on 2-DE maps and 15.43% had changed (P<0.05; ≥1.5-fold) significantly in quantity between the +P and −P groups. These proteins are involved in several major metabolic pathways, including photosynthesis, carbohydrate metabolism, energy metabolism, secondary metabolism, signal transduction, protein synthesis, cell rescue and cell defense and virulence. The results showed that the reduction in photosynthesis under low phosphorus treatment was due to the down-regulation of the proteins involved in CO2 enrichment, the Calvin cycle and the electron transport system. Electron transport and photosynthesis restrictions resulted in a large accumulation of peroxides. Maize has developed many different reactive oxygen species (ROS) scavenging mechanisms to cope with low phosphorus stress, including up-regulating its antioxidant content and antioxidase activity. After being subjected to phosphorus stress over a long period, maize may increase its internal phosphorus utilization efficiency by altering photorespiration, starch synthesis and lipid composition. These results provide important information about how maize responds to low phosphorus stress.

The Crystal Structure of the Anti-σ Factor CnrY in Complex with the σ Factor CnrH Shows a New Structural Class of Anti-σ Factors Targeting Extracytoplasmic Function σ Factors

Gene expression in bacteria is regulated at the level of transcription initiation, a process driven by σ factors. The regulation of σ factor activity proceeds from the regulation of their cytoplasmic availability, which relies on specific inhibitory proteins called anti-σ factors. With anti-σ factors regulating their availability according to diverse cues, extracytoplasmic function σ factors (σECF) form a major signal transduction system in bacteria. Here, structure:function relationships have been characterized in an emerging class of minimal-size transmembrane anti-σ factors, using CnrY from Cupriavidus metallidurans CH34 as a model. This study reports the 1.75-Å-resolution structure of CnrY cytosolic domain in complex with CnrH, its cognate σECF, and identifies a small hydrophobic knob in CnrY as the major determinant of this interaction in vivo. Unsuspected structural similarity with the molecular switch regulating the general stress response in α-proteobacteria unravels a new class of anti-σ factors targeting σECF. Members of this class carry out their function via a 30-residue stretch that displays helical propensity but no canonical structure on its own.

Phospholipase C isoforms expression in mouse endothelium (1075.2)

Phospholipase C (PLC) is a major signal transduction component through the regulation of various intracellular pathways, including PKC and intracellular Ca2+ channels. Up to 13 mammalian PLC isoforms have been identified and are classified in 6 families: PLC‐β, γ, δ, ε, ζ and η. Although expression of PLCs is tissue‐specific, combined expression of different PLCs has been reported. However, endothelial PLC expression remains to be established. Therefore, we sought to determine the expression pattern of PLC in mouse resistance arteries. We first studied the expression of PLC isoforms in mesenteric arteries. We found mRNA encoding for most PLCs with the exception of ζ1, η1 and η2 in whole mesenteric arteries. Similar results were obtained in middle cerebral, coronary and pulmonary arteries. We then elucidated the intracellular distribution of PLCs β3, γ1 and δ1, the main mammalian isoforms, in endothelial cells with in situ immunocytochemistry. We observed a diffuse staining in endothelium with no clearly defined heterogeneous distribution of all three PLCs. Further investigation is necessary to determine the specific PLC isoforms involved in endothelial localized Ca2+ dynamics. Taken together, these studies might strengthen our understanding of endothelial Ca2+ homeostasis mechanisms and therefore endothelial function.Grant Funding Source: Supported by FRQS, HSFC, SQHA and FICM.

A novel mode of regulation of the Staphylococcus aureus Vancomycin-resistance-associated response regulator VraR mediated by Stk1 protein phosphorylation

The Staphylococcus aureus Vancomycin-resistance-associated response regulator VraR is known as an important response regulator, member of the VraTSR three-component signal transduction system that modulates the expression of the cell wall stress stimulon in response to a number of different cell wall active antibiotics. Given its crucial role in regulating gene expression in response to antibiotic challenges, VraR must be tightly regulated. We report here for the first time in S. aureus convergence of two major signal transduction systems, serine/threonine protein kinase and two (three)-component systems. We demonstrate that VraR can be phosphorylated by the staphylococcal Ser/Thr protein kinase Stk1 and that phosphorylation negatively affects its DNA-binding properties. Mass spectrometric analyses and site-directed mutagenesis identified Thr106, Thr119, Thr175 and Thr178 as phosphoacceptors. A S. aureus ΔvraR mutant expressing a VraR derivative that mimics constitutive phosphorylation, VraR_Asp, still exhibited markedly decreased antibiotic resistance against different cell wall active antibiotics, when compared to the wild-type, suggesting that VraR phosphorylation may represent a novel and presumably more general mechanism of regulation of the two (three)-component systems in staphylococci.

Comparative proteomic profiling during ovarian development of the shrimp Metapenaeus ensis

Two-dimensional electrophoresis and mass spectrometry were used to identify proteins that are differentially expressed during ovarian maturation in Metapenaeus ensis. 87 spots with consistently significant quantitative differences (≥ 1.5-fold for vol%) among stage I, III and V ovaries were chosen for MS/MS analysis. 45 spots were significantly matched to known proteins in the database (Mascot score >40). Half of them were down-regulated, in contrast to 9 out of 45 proteins that were up-regulated as ovarian maturation proceeded. Functionally, these identified proteins could be classified into five major groups, including cytoskeleton (11 %), metabolism (18 %), signal transduction (32 %), gene expression (14 %) and immune response (7 %). Among the differentially expressed reproduction-related proteins, the mRNA expression level of cellular retinoic acid/retinol binding protein in M. ensis (MeCRABP) during ovarian maturation was further characterized by quantitative real-time PCR. It was down-regulated during ovarian maturation. In situ hybridization further revealed that MeCRABP transcript was localized in ooplasm of previtellogenic oocytes but not in vitellogenic oocytes. These results demonstrate the application of proteomic analysis for identification of proteins involved in shrimp ovarian maturation and they provide new insights into ovarian development.

IFN-γ/STAT1-Dependent Regulation Of Antigen Presenting Cell (APC) Function: Role In Graft-Versus-Host Disease (GVHD)

Interferon-gamma (IFN-γ) is a pleiotropic cytokine that has diverse activities in mediating host defense and immunopathology and is involved in both innate an adaptive immunity. Furthermore, IFN-γ has been shown to be a key regulator of GVHD. STAT1 is the major downstream signal transducer for IFN-γ. IFN-γ has been shown to up-regulate MHC class II expression on macrophages and dendritic cells. In this study, we unexpectedly observed that STAT1-deficient mouse bone marrow-derived dendritic cells (BM-DCs) displayed significantly increased MHC class II, CD86, CD80, CD40 expression compared to wild type BM-DCs upon LPS stimulation. To determine whether these LPS-maturated STAT1-/- BM-DCs are functional, freshly isolated pan-T cells from BALB/c (H2d) mice were stimulated with either irradiated LPS-maturated STAT1+/+ or STAT1-/- BMDCs from 129Sv [H2b] mice at different DC/Responder ratios for 5 days. Pan-T cell proliferation was measured using by 3H-incorporation or in separate assays by CFSE dilution. Both proliferation assays clearly demonstrated that STAT1-/- BM-DCs were significantly more potent stimulators in Mixed Lymphocyte Reaction (MLR) assays compared to STAT1+/+ BM-DCs. Further studies demonstrated that this increased surface MHC II expression was also observed in LPS-stimulated IFNγR-/- BM-DCs or on wild type BM-DCs treated with neutralizing IFNγ Abs but not in LPS-treated IFNα-R-/- BM-DCs.STAT1 deficient DCs have been reported to be defective in IL-12 production upon stimulation with various Toll-like receptors (TLRs). However, we were able to observe that STAT1-/- BM-DCs had increased CD40 expression after LPS maturation, and more importantly, STAT1 deficient BM-DCs had significantly increased IL-12 production upon treatment with CD40-ligand. These data suggest that STAT1 deficiency in LPS-stimulated DCs results not only in increased expression of MHC class II and costimulatory molecules, but also in enhanced CD40-dependent IL-12 production promoting generation of Th1 and Tc1 cell of wildtype responder cells.To test the influence of IFNγ/STAT1 deficiency in host APC on GVHD induction, wild type or STAT1-deficient 129 mice (H2b) underwent allogeneic Bone Marrow Transplantation (BMT) following lethal irradiation (1044 rad) receiving BALB/c spleen cells. 129.STAT1-/- recipients had significantly accelerated GVHD mortality (MST 8 days vs. 5 days, log rank test p=0.004) compared with wild type recipients. In contrast, STAT1-deficient syngeneic controls did not show enhanced mortality or morbidity ruling out that the observed accelerated mortality following allogeneic BMT was due to conditioning toxicity. On day+4 post-BMT animals were sacrificed and splenocytes were analyzed by flow cytometry. We could observe a significantly enhanced expansion and activation of donor CD4 and CD8 T cells in STAT1-/- recipients. Importantly, the increased MHC II expression was confirmed in host CD11b+ and CD11c+ cell populations. To clarify that STAT1 deficiency in host APCs do contribute to increased GVHD induction, we generated STAT1-/-→STAT1+/+, and STAT1+/+→STAT1+/+ radiation chimeric mice as recipients so that only the hematopoietic cells were STAT1 deficient. We again observed significantly increased GVHD mortality and increased activation of fully MHC-mismatched donor T cells in STAT1-/-→STAT1+/+ recipients following allogeneic BMT and GVHD induction. Similar results i.e. increased GVHD mortality, increased donor cell activation and increased MHC II expression on host CD11c+, B220+ cells were also found in IFNγR-/- recipient mice when compared with control mice following full MHC-mismatched allogeneic BMT. In summary our data reveal previously unknown effects of IFNγ/STAT1 signaling on APCs function suggesting that LPS-driven maturation of APC's is negatively regulated by IFNγ/STAT1 leading to enhanced expression of MHC class II, costimulatory molecules and responsiveness to CD40-ligation and subsequent IL-12 production in the absence of STAT1. Furthermore, our results explain the accelerated GVHD induction and demonstrate that IFN-γ/STAT1 signaling in host APC mitigates the development of GVHD. Disclosures:Lentzsch:Celgene: Research Funding.

Jak-Stat signaling pathway may play a role in the pathogenesis of cholesteatoma

PurposeJak-Stat signaling pathway is one of the major signal transduction cascades which regulates most of the cellular events such as cell proliferation, differentiation, cell migration and apoptosis. This study aims to determine the activity of Jak-Stat signaling pathway in the pathogenesis of cholesteatoma. Materials and MethodsCholesteatoma and skin samples were obtained from 10 patients who underwent tympanomastoidectomy for chronic otitis media with cholesteatoma. Immunohistochemical analysis of cholesteatoma and skin was performed using anti-Jak1, anti-Jak2, anti-Jak3, anti-Stat1, anti-Stat2, anti-Stat3, anti-Stat4 and anti-Stat5 antibodies. The immunoreactivities in cholesteatoma and skin were quantified using H-score measurement and statistical comparison was performed. ResultsJak1, Jak2, Jak3, Stat1 and Stat3 immunoreactivities were not detected in cholesteatoma; in contrast to the skin (129.8; 226.7; 33.0; 66.4;115.9). In addition, when H-score measurements of Stat2, Stat4 and Stat5 immunoreactivities were compared between cholesteatoma (172.8; 166.7; 120.0) and skin (400.0; 284.9; 292.0), statistically significant differences were found (p<0.0001, p<0.0001, p<0.0001). ConclusionsA remarkable deficiency in the family members of Jak-Stat signaling pathway was demonstrated in cholesteatoma. Therefore, perturbations in Jak-Stat signaling pathway may play a role in the pathogenesis of cholesteatoma.

IFN-γ (+874) and not TNF-α (−308) is associated with HBV-HCC risk in India

Tumor necrosis factor (TNF)-α and interferon (IFN)-γ, the pro-inflammatory Th1 cytokines are the indispensable coordinators of the inflammatory responses involved in hepatitis B virus (HBV) pathogenesis. This study attempted to evaluate any possible association among TNF-α (-308G>A) and IFN-γ (+874T/A) genotypes, the spontaneous blood and mRNA levels and expression of their major signal transducers, namely STAT1 and NF-кB with hepatitis B virus-induced hepatocellular carcinoma (HCC) susceptibility in India. For this, 398 subjects (146 controls, 68 inactive-HBV-carriers, 64 chronic-active HBV patients, 61 HBV-cirrhotics, and 59 HBV-HCC subjects) were enrolled. Polymerase chain reaction-restriction fragment length polymorphism, allele-specific PCR, enzyme-linked immunosorbent assay, reverse transcriptase-PCR, and Western blot analysis were done for assessing polymorphism, blood levels, mRNA expression, and protein expression of signal transducers, respectively, of TNF-α and IFN-γ. The study revealed no significant association of TNF-α (-308) GA genotype, while a significant negative association of IFN-γ (+874) TA and AA genotypes, in HBV-HCC risk. Moreover, blood levels of TNF-α were significantly elevated as disease progresses to HCC, while IFN-γ levels were raised in HCC patients only. Besides, IFN-γ mRNA levels were significantly elevated in cirrhotics, with no change observed in TNF-α transcript levels. Moreover, NF-кB expression also consistently increased during HCC progression. These observations suggest a vital negative association of IFN-γ (+874) with HBV-HCC risk, with no significant association evident in TNF-α (-308). However, the TNF-α and IFN-γ levels markedly increased in HCC development.

Tumor necrosis factor receptor associated factor-4: An adapter protein overexpressed in metastatic prostate cancer is regulated by microRNA-29a

The tumor necrosis factor receptor (TNFR)-associated factor 4 (TRAF4) is a member of TRAF family proteins that act as major signal transducers of the TNF receptor and the interleukin-1 receptor/Toll-like receptor (IL-1R/TLR) superfamily. TRAF4 has been reported to be overexpressed in various human cancers. However, the exact mechanisms that regulate the expression of TRAF4 still remain elusive. The objective of the present study was to investigate the regulatory mechanism of TRAF4 expression in prostate cancer. We initially identified microRNA-29a (miR‑29a) as a possible candidate to bind TRAF4 3' untranslated region (3'UTR) by the algorithm, TargetScan. The expression of TRAF4 mRNA and protein was inversely associated with miR-29a expression in prostate cancer cell lines (LNCaP, DU145 and PC3). TRAF4 expression was reduced by the introduction of mimic miR-29a in LNCaP cells. Luciferase activity from the construct harboring wild-type TRAF4 3'UTR was reduced by the mimic miR-29a and this reduction was diminished by introducing mutations at the predicted miR-29a binding site. On the other hand, TRAF4 was upregulated when transfected with the inhibitor of miR-29a in DU145 and PC3 cells. TRAF4 was significantly upregulated in patients with metastatic prostate cancer compared to those with localized prostate cancer. Furthermore, there was a significant inverse correlation between TRAF4 and miR-29a expression in tumor tissues from radical prostatectomy. Considered together, our results suggest that the tumor suppressor microRNA, miR-29a, is one of the regulators of TRAF4 expression in metastatic prostate cancer.

VEGFR and Type-V RTK Activation and Signaling

Vascular endothelial growth factor receptors (VEGFRs) in vertebrates play essential roles in the regulation of angiogenesis and lymphangiogenesis. VEGFRs belong to the receptor-type tyrosine kinase (RTK) supergene family. They consist of a ligand-binding region with seven immunoglobulin (7 Ig) -like domains, a trans-membrane (TM) domain, and a tyrosine kinase (TK) domain with a long kinase insert (KI) (also known as a type-V RTK). Structurally, VEGFRs are distantly related to the members of the M-colony stimulating factor receptor/platelet-derived growth factor receptor (CSFR)/(PDGFR) family, which have five immunoglobulin (5 Ig)-like domains. However, signal transduction in VEGFRs significantly differs from that in M-CSFR/PDGFRs. VEGFR2, the major signal transducer for angiogenesis, preferentially uses the phospholipase Cγ-protein kinase C (PLC-γ-PKC)-MAPK pathway, whereas M-CSFR/PDGFRs use the PI3 kinase-Ras-MAPK pathway for cell proliferation. In phylogenetic development, the VEGFR-like receptor in nonvertebrates appears to be the ancestor of the 7 Ig- and 5 Ig-RTK families because most nonvertebrates have only a single 7 Ig-RTK gene. In mammals, VEGFRs are deeply involved in pathological angiogenesis, including cancer and inflammation. Thus, an efficient inhibitor targeting VEGFRs could be useful in suppressing various diseases.