Microbiota enterotoxigenic Bacteroides fragilis-secreted BFT-1 promotes breast cancer cell stemness and chemoresistance through its functional receptor NOD1.

Tumor-resident microbiota in breast cancer promotes cancer initiation and malignant progression. However, targeting microbiota to improve the effects of breast cancer therapy has not been investigated in detail. Here, we evaluated the microbiota composition of breast tumors and found that enterotoxigenic Bacteroides fragilis (ETBF) was highly enriched in the tumors of patients who did not respond to taxane-based neoadjuvant chemotherapy. ETBF, albeit at low biomass, secreted the toxic protein BFT-1 to promote breast cancer cell stemness and chemoresistance. Mechanistic studies showed that BFT-1 directly bound to NOD1 and stabilized NOD1 protein. NOD1 was highly expressed on ALDH+ breast cancer stem cells (BCSCs) and cooperated with GAK to phosphorylate NUMB and promote its lysosomal degradation, thereby activating the NOTCH1-HEY1 signaling pathway to increase BCSCs. NOD1 inhibition and ETBF clearance increase the chemosensitivity of breast cancer by impairing BCSCs.

Nonpeptidic quinazolinone derivatives as dual nucleotide-binding oligomerization domain-like receptor 1/2 antagonists for adjuvant cancer chemotherapy.

Nucleotide-binding oligomerization domain-containing protein 1 and 2 (NOD1/2) receptors are potential immune checkpoints. In this article, a quinazolinone derivative (36b) as a NOD1/2 dual antagonist was identified that significantly sensitizes B16 tumor-bearing mice to paclitaxel treatment by inhibiting both nuclear factor κB (NF-κB) and mitogen-activated protein kinase inflammatory signaling that mediated by NOD1/2.

The Role of the NOD1/Rip2 Signaling Pathway in Myocardial Remodeling in Spontaneously Hypertensive Rats.

BACKGROUND Chronic hypertension changes the function and structure of the heart and blood vessels. This study aimed to explore the role of the NOD1/Rip2 (nucleotide-binding oligomerization domain 1/receptor-interacting protein 2) signaling pathway in myocardial remodeling in spontaneously hypertensive rats (SHRs). MATERIAL AND METHODS Blood pressure was measured using a tail cuff. The cardiac structure was observed using echocardiography. Slices of the myocardium were stained with hematoxylin and eosin. The expression of NOD1 and Rip2 was detected using real-time polymerase chain reaction, western blot, and immunohistochemistry. The content and distribution of collagen in the myocardium were observed using Van Gieson staining. Enzyme-linked immunosorbent assay was used to detect the interleukin-1 (IL-1) concentrations. SHRs were treated with the NOD1 agonist iE-DAP and NOD1 inhibitor ML130. RESULTS The NOD1 agonist increased blood pressure in SHRs, and the NOD1 inhibitor decreased blood pressure; the interventricular septum thickness (IVST) and left ventricular posterior wall thickness (LVPWT) of the agonist-treated group were thicker than those of the control group, and the antagonist exerted the opposite effects. The levels of the NOD1 and Rip2 mRNAs and proteins, serum IL-1 concentration, and myocardial collagen volume fraction (CVF%) increased in SHRs in the NOD1 agonist group, but the levels of NOD1 and Rip2, serum IL-1 concentration, and myocardial collagen volume fraction (CVF%) decreased in SHRs in the NOD1 inhibitor group. CONCLUSIONS NOD1/Rip2 expression increased during the progression of myocardial remodeling in SHRs. The NOD1 agonist increased NOD1 expression and promoted myocardial remodeling, while the NOD1 antagonist reduced NOD1/Rip2 expression and protected against myocardial remodeling.

Identification of benzofused five-membered sultams, potent dual NOD1/NOD2 antagonists in vitro and in vivo.

Nucleotide-binding oligomerization domain-containing proteins 1 and 2 play important roles in immune system activation. Recently, a shift has occurred due to the emerging knowledge that preventing nucleotide-binding oligomerization domains (NODs) signaling could facilitate the treatment of some cancers, which warrants the search for dual antagonists of NOD1 and NOD2. Herein, we undertook the synthesis and identification of a new class of derivatives of dual NOD1/NOD2 antagonists with novel benzofused five-membered sultams. Compound 14k was finally demonstrated to be the most potent molecule that inhibits both NOD1-and NOD2-stimulated NF-κB and MAPK signaling in vitro and in vivo.

Structural features and functional activities of benzimidazoles as NOD2 antagonists.

NOD1 and NOD2 are pattern recognition receptors that have important roles in innate immune responses. Although their overactivation has been linked to a number of diseases, NOD2 in particular remains a virtually unexploited target in this respect, with only one structural class of antagonist reported. To gain insight into the structure-activity relationships of NOD2 antagonists, a series of novel analogs was designed and synthesized, and then screened for antagonist activity versus NOD2, and counter-screened versus NOD1. Compounds 32 and 38 were identified as potent and moderately selective NOD2 antagonists, and 33 and 42 as dual NOD1/NOD2 antagonists, with balanced activities against both targets in the low micromolar range. These data enable in-depth exploration of their structure-activity relationships and provide deeper understanding of the structural features required for NOD2 antagonism.

THP-1 Cells and Pro-inflammatory Cytokine Production: An in Vitro Tool for Functional Characterization of NOD1/NOD2 Antagonists.

THP-1 cells express high levels of native functional nucleotide-binding oligomerization domain 1 (NOD1), NOD2, and Toll-like receptor 4 (TLR4) receptors, and have often been used for investigating the immunomodulatory effects of small molecules. We postulated that they would represent an ideal cell-based model for our study, the aim of which was to develop a new in vitro tool for functional characterization of NOD antagonists. NOD antagonists were initially screened for their effect on NOD agonist-induced interleukin-8 (IL-8) release. Next, we examined the extent to which the selected NOD antagonists block the NOD-TLR4 synergistic crosstalk by measuring the effect of NOD antagonism on tumor necrosis factor-α (TNF-α) secretion from doubly activated THP-1 cells. Overall, the results obtained indicate that pro-inflammatory cytokine secretion from THP-1 provides a valuable, simple and reproducible in vitro tool for functional characterization of NOD antagonists.

Salutaxel, a Conjugate of Docetaxel and a Muramyl Dipeptide (MDP) Analogue, Acts as Multifunctional Prodrug That Inhibits Tumor Growth and Metastasis.

Salutaxel (3) is a conjugate of docetaxel (7) and a muramyl dipeptide (MDP) analogue. Docetaxel (7) has been recognized as a highly active chemotherapeutic agent against various cancers. MDP and its analogues are powerful potentiators of the antitumor actions of various tumor-necrotizing agents. This article documents the discovery of compound 3 and presents pharmacological proof of its biological function in tumor-bearing mice. Drug candidate 3 was superior to compound 7 in its ability to prevent tumor growth and metastasis. Compound 3 suppressed myeloid-derived suppressor cell (MDSC) accumulation in the spleens of tumor-bearing mice and decreased various serum inflammatory cytokines levels. Furthermore, compound 3 antagonized the nucleotide-binding oligomerization domain-like receptor 1 (NOD1) signaling pathway both in vitro and in vivo.

Discovery of 1,4-Benzodiazepine-2,5-dione (BZD) Derivatives as Dual Nucleotide Binding Oligomerization Domain Containing 1/2 (NOD1/NOD2) Antagonists Sensitizing Paclitaxel (PTX) To Suppress Lewis Lung Carcinoma (LLC) Growth in Vivo.

Nucleotide-binding oligomerization domain-like receptors (NLRs) are intracellular sensors of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Previously, we reported nucleotide-binding oligomerization domain-containing protein 1 (NOD1) antagonists (11, 12) and a NOD2 antagonist (9) that sensitized docetaxel (DTX) or paclitaxel (PTX) treatment for breast or lung cancer. In this article, we describe for the first time a 1,4-benzodiazepine-2,5-dione (BZD) derivative (26bh) that acts as a dual NOD1/NOD2 antagonist and inhibits both nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) inflammatory signaling, thereby sensitizing PTX to suppress Lewis lung carcinoma (LLC) growth. After investigation of the compound's cytotoxicity, a systematic structure-activity relationship (SAR) was completed and revealed several key factors that were necessary to maintain antagonistic ability. This study establishes the possibility for using adjuvant treatment to combat cancer by antagonizing both NOD1 and NOD2 signaling.

Identification of indole scaffold-based dual inhibitors of NOD1 and NOD2.

NOD1 and NOD2 are important members of the pattern recognition receptor family and play a crucial role within the context of innate immunity. However, overactivation of NODs, especially of NOD1, has also been implicated in a number of diseases. Surprisingly, NOD1 remains a virtually unexploited target in this respect. To gain additional insight into the structure-activity relationships of NOD1 inhibitors, a series of novel analogs has been designed and synthesized and then screened for their NOD1-inhibitory activity. Selected compounds were also investigated for their NOD2-inhibitory activity. Two compounds 4 and 15, were identified as potent mixed inhibitors of NOD1 and NOD2, displaying a balanced inhibitory activity on both targets in the low micromolar range. The results obtained have enabled a deeper understanding of the structural requirements for NOD1 and NOD2 inhibition.

Synthesis of characteristic Mycobacterium peptidoglycan (PGN) fragments utilizing with chemoenzymatic preparation of meso-diaminopimelic acid (DAP), and their modulation of innate immune responses.

Peptidoglycan (PGN) is a major component of bacterial cell wall and is recognized as a potent immunostimulant. The PGN in the cell envelope of Mycobacterium Tuberculosis has been shown to possess several unique characteristics including the presence of N-glycolyl groups (in addition to N-acetyl groups) in the muramic acid residues, and amidation of the free carboxylic acid of d-Glu or of meso-DAP in the peptide chains. Using a newly developed, highly stereoselective, chemoenzymatic approach for the synthesis of meso-DAP in peptide stems, we successfully synthesized for the first time, a series of Mycobacterium PGN fragments that include both mono- and disaccharides of MurNGlyc or 1,6-anhydro-MurNGlyc, as well as peptide-amidated variants. The ability of these PGN fragments to stimulate the immune system through activation of human Nod1 and Nod2 was examined. The PGN fragments were found to modulate immune stimulation, specifically, amidation at the d-Glu and meso-DAP in the peptide stem strongly reduced hNod1 activation. This effect was dependent on modification position. Additionally, N-glycolyl (instead of acetyl) of muramic acid was associated with slightly reduced human Nod1 and Nod2 stimulatory capabilities.

Inflammatory Signaling by NOD-RIPK2 Is Inhibited by Clinically Relevant Type II Kinase Inhibitors.

RIPK2 mediates pro-inflammatory signaling from the bacterial sensors NOD1 and NOD2, and is an emerging therapeutic target in autoimmune and inflammatory diseases. We observed that cellular RIPK2 can be potently inhibited by type II inhibitors that displace the kinase activation segment, whereas ATP-competitive type I inhibition was only poorly effective. The most potent RIPK2 inhibitors were the US Food and Drug Administration-approved drugs ponatinib and regorafenib. Their mechanism of action was independent of NOD2 interaction and involved loss of downstream kinase activation as evidenced by lack of RIPK2 autophosphorylation. Notably, these molecules also blocked RIPK2 ubiquitination and, consequently, inflammatory nuclear factor κB signaling. In monocytes, the inhibitors selectively blocked NOD-dependent tumor necrosis factor production without affecting lipopolysaccharide-dependent pathways. We also determined the first crystal structure of RIPK2 bound to ponatinib, and identified an allosteric site for inhibitor development. These results highlight the potential for type II inhibitors to treat indications of RIPK2 activation as well as inflammation-associated cancers.

NOD1, a new player in cardiac function and calcium handling.

AIMS: Inflammation is a significant contributor to cardiovascular disease and its complications; however, whether the myocardial inflammatory response is harmonized after cardiac injury remains to be determined. Some receptors of the innate immune system, including the nucleotide-binding oligomerization domain-like receptors (NLRs), play key roles in the host response after cardiac damage. Nucleotide-binding oligomerization domain containing 1 (NOD1), a member of the NLR family, is expressed in the heart, but its functional role has not been elucidated. We determine whether selective NOD1 activation modulates cardiac function and Ca(2+) signalling. METHODS AND RESULTS: Mice were treated for 3 days with the selective NOD1 agonist C12-iE-DAP (iE-DAP), and cardiac function and Ca(2+) cycling were assessed. We found that iE-DAP treatment resulted in cardiac dysfunction, measured as a decrease in ejection fraction and fractional shortening. Cardiomyocytes isolated from iE-DAP-treated mice displayed a decrease in the L-type Ca(2+) current, [Ca(2+)]i transients and Ca(2+) load, and decreased expression of phospho-phospholamban, sarcoplasmic reticulum-ATPase, and Na(+)-Ca(2+) exchanger. Furthermore, iE-DAP prompted 'diastolic Ca(2+) leak' in cardiomyocytes, resulting from increased Ca(2+) spark frequency and RyR2 over-phosphorylation. Importantly, these iE-DAP-induced changes in Ca(2+) cycling were lost in NOD1(-/-) mice, indicating that iE-DAP exerts its actions through NOD1. Co-treatment of mice with iE-DAP and a selective inhibitor of NF-κB (BAY11-7082) prevented cardiac dysfunction and Ca(2+) handling impairment induced by iE-DAP. CONCLUSION: Our data provide the first evidence that NOD1 activation induces cardiac dysfunction associated with excitation-contraction coupling impairment through NF-κB activation and uncover a new pro-inflammatory player in the regulation of cardiovascular function.

Manual de monitoramento da qualidade dos registros de enfermagem na assistência domiciliar / Manual de monitoreo de la calidad de los registros de enfermería en la atención domiciliaria / Manual for monitoring the quality of nursing home care records

RESUMO Objetivo: construir e validar um instrumento para monitorar a qualidade dos registros de enfermagem no Programa de Assistência Domiciliar (PAD) em um hospital universitário. Método: estudo metodológico envolvendo a elaboração de um manual e submetido à validação de conteúdo por seis juízes sob consenso ≥ 80%. A coleta ocorreu em 2012 por meio de questionário contendo: evolução de enfermagem, diagnóstico e prescrição de enfermagem e normas para os registros da equipe de enfermagem preconizadas pelo Conselho Regional de Enfermagem-SP e pela instituição. Os itens do manual foram julgados de acordo com as variáveis - relevância, pertinência, clareza e simplicidade. Resultados: das 39 proposições 100% atingiram consenso ≥ 80% em relevância, pertinência e clareza; 92,3% em simplicidade. Os itens sono/repouso, mobilidade e checagem nas atividades prescritas não atingiram consenso mínimo favorável, sendo aprimorados pelas sugestões dos juízes. Conclusão: acreditamos que o instrumento possibilitará a melhoria dos processos de trabalho no PAD. .

RESUMEN Objetivo: construir y validar un instrumento para monitorear la calidad del registros de enfermería en Programa de Atención Domiciliaria (PAD) de un Hospital Universitario. Metodo: estudio metodológico. Fue construido un manual y sometió a validación de contenido por seis jueces bajo el consenso ≥80%. La recogida currió en 2012, con un cuestionario que contiene: evolución de enfermería, diagnóstico y prescripción de enfermería y normas para los registros del personal de enfermaria estabelecidas por Consejo Regional de Enfermería-SP y por la institución. Los artículos del manual fueran juzgadso conforme las variables relevancia, pertinencia, claridad y sencillez. Resultados: de las 39 proposiciones 100% alcanzó consenso ≥ 80% en la relevancia, pertinencia y claridad; 92,3% en la simplicidad. Los itens sueño/resto, movilidad y verificar las actividades prescritas no alcanzó consenso favorable, siendo mejoradas por las sugerencias de los jueces. Conclusión: creemos que el instrumento permitirá la mejora de los procesos de trabajo en PAD. .

ABSTRACT Objective: to build and validate an instrument aimed at monitoring the quality of nursing records in the Home Care Program (HCP) of a university hospital. Method: methodological study involving the elaboration of a manual, whose content was later submitted to six experts for validation, reaching a ≥ 80% consensus. The data collection process was carried out in 2012 by means of a questionnaire comprised of the following issues: nursing evolution, nursing diagnosis, and nursing prescription, and standards for the nursing team recommended by the Regional Nursing Council of São Paulo and by the assessed institution. Manual items were judged according to the following variables: relevance, pertinence, clarity and simplicity. Results: of the 39 propositions, 100% achieved ≥ 80% agreement in the relevance, pertinence and clarity variables; 92.3% in the simplicity variable. Sleep/rest, Mobility and Check-out variables did not reach a favorable minimum consensus in the prescribed activities and were improved following suggestions from the experts. Conclusion: we believe that the instrument will enable the improvement of the HCP’s work process. .

The cofilin phosphatase slingshot homolog 1 (SSH1) links NOD1 signaling to actin remodeling.

NOD1 is an intracellular pathogen recognition receptor that contributes to anti-bacterial innate immune responses, adaptive immunity and tissue homeostasis. NOD1-induced signaling relies on actin remodeling, however, the details of the connection of NOD1 and the actin cytoskeleton remained elusive. Here, we identified in a druggable-genome wide siRNA screen the cofilin phosphatase SSH1 as a specific and essential component of the NOD1 pathway. We show that depletion of SSH1 impaired pathogen induced NOD1 signaling evident from diminished NF-κB activation and cytokine release. Chemical inhibition of actin polymerization using cytochalasin D rescued the loss of SSH1. We further demonstrate that NOD1 directly interacted with SSH1 at F-actin rich sites. Finally, we show that enhanced cofilin activity is intimately linked to NOD1 signaling. Our data thus provide evidence that NOD1 requires the SSH1/cofilin network for signaling and to detect bacterial induced changes in actin dynamics leading to NF-κB activation and innate immune responses.

Nucleotide-binding oligomerization domain (NOD) inhibitors: a rational approach toward inhibition of NOD signaling pathway.

Dysregulation of nucleotide-binding oligomerization domains 1 and 2 (NOD1 and NOD2) has been implicated in the pathology of various inflammatory disorders, rendering them and their downstream signaling proteins potential therapeutic targets. Selective inhibition of NOD1 and NOD2 signaling could be advantageous in treating many acute and chronic diseases; therefore, harnessing the full potential of NOD inhibitors is a key topic in medicinal chemistry. Although they are among the best studied NOD-like receptors (NLRs), the therapeutic potential of pharmacological modulation of NOD1 and NOD2 is largely unexplored. This review is focused on the scientific progress in the field of NOD inhibitors over the past decade, including the recently reported selective inhibitors of NOD1 and NOD2. In addition, the potential approaches to inhibition of NOD signaling as well as the advantages and disadvantages linked with inhibition of NOD signaling are discussed. Finally, the potential directions for drug discovery are also discussed.

NOD1 activation induces cardiac dysfunction and modulates cardiac fibrosis and cardiomyocyte apoptosis.

The innate immune system is responsible for the initial response of an organism to potentially harmful stressors, pathogens or tissue injury, and accordingly plays an essential role in the pathogenesis of many inflammatory processes, including some cardiovascular diseases. Toll like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors (NLRs) are pattern recognition receptors that play an important role in the induction of innate immune and inflammatory responses. There is a line of evidence supporting that activation of TLRs contributes to the development and progression of cardiovascular diseases but less is known regarding the role of NLRs. Here we demonstrate the presence of the NLR member NOD1 (nucleotide-binding oligomerization domain containing 1) in the murine heart. Activation of NOD1 with the specific agonist C12-iEDAP, but not with the inactive analogue iE-Lys, induces a time- and dose-dependent cardiac dysfunction that occurs concomitantly with cardiac fibrosis and apoptosis. The administration of iEDAP promotes the activation of the NF-κB and TGF-ß pathways and induces apoptosis in whole hearts. At the cellular level, both native cardiomyocytes and cardiac fibroblasts expressed NOD1. The NLR activation in cardiomyocytes was associated with NF-κB activation and induction of apoptosis. NOD1 stimulation in fibroblasts was linked to NF-κB activation and to increased expression of pro-fibrotic mediators. The down-regulation of NOD1 by specific siRNAs blunted the effect of iEDAP on the pro-fibrotic TGF-ß pathway and cell apoptosis. In conclusion, our report uncovers a new pro-inflammatory target that is expressed in the heart, NOD1. The specific activation of this NLR induces cardiac dysfunction and modulates cardiac fibrosis and cardiomyocyte apoptosis, pathological processes involved in several cardiac diseases such as heart failure.

Roles of NOD1 (NLRC1) and NOD2 (NLRC2) in innate immunity and inflammatory diseases.

NOD1 {nucleotide-binding oligomerization domain 1; NLRC [NOD-LRR (leucine-rich repeat) family with CARD (caspase recruitment domain) 1]} and NOD2 (NLRC2) are among the most prominent members of the NLR (NOD-LRR) family -proteins that contain nucleotide-binding NACHT domains and receptor-like LRR domains. With over 20 members identified in humans, NLRs represent important components of the mammalian innate immune system, serving as intracellular receptors for pathogens and for endogenous molecules elaborated by tissue injury. NOD1 and NOD2 proteins operate as microbial sensors through the recognition of specific PG (peptidoglycan) constituents of bacteria. Upon activation, these NLR family members initiate signal transduction mechanisms that include stimulation of NF-κB (nuclear factor-κB), stress kinases, IRFs (interferon regulatory factors) and autophagy. Hereditary polymorphisms in the genes encoding NOD1 and NOD2 have been associated with an increasing number of chronic inflammatory diseases. In fact, potential roles for NOD1 and NOD2 in inflammatory disorders have been revealed by investigations using a series of animal models. In the present review, we describe recent experimental findings associating NOD1 and NOD2 with various autoimmune and chronic inflammatory disorders, and we discuss prospects for development of novel therapeutics targeting these NLR family proteins.

Discovery and characterization of 2-aminobenzimidazole derivatives as selective NOD1 inhibitors.

NLR family proteins play important roles in innate immune response. NOD1 (NLRC1) activates various signaling pathways including NF-κB in response to bacterial ligands. Hereditary polymorphisms in the NOD1 gene are associated with asthma, inflammatory bowel disease, and other disorders. Using a high throughput screening (HTS) assay measuring NOD1-induced NF-κB reporter gene activity, followed by multiple downstream counter screens that eliminated compounds impacting other NF-κB effectors, 2-aminobenzimidazole compounds were identified that selectively inhibit NOD1. Mechanistic studies of a prototypical compound, Nodinitib-1 (ML130; CID-1088438), suggest that these small molecules cause conformational changes of NOD1 in vitro and alter NOD1 subcellular targeting in cells. Altogether, this inaugural class of inhibitors provides chemical probes for interrogating mechanisms regulating NOD1 activity and tools for exploring the roles of NOD1 in various infectious and inflammatory diseases.

Activation of the nucleotide oligomerization domain signaling pathway by the non-bacterially derived xanthone drug 5'6-dimethylxanthenone-4-acetic acid (Vadimezan).

The cytosolic nucleotide-binding oligomerization domain 1 (NOD1)/CARD4 and NOD2/CARD15 proteins are members of NOD-like receptors recognizing specific motifs within peptidoglycans of both Gram-negative and Gram-positive bacteria. NOD1 and NOD2 signal via the downstream adaptor serine/threonine kinase RIP2/CARDIAK/RICK to initiate NF-kappaB activation and the release of inflammatory cytokines/chemokines. In this report, we show that 5,6-dimethylxanthenone-4-acetic acid (DMXAA), a cell-permeable, small molecule that has anti-tumor activity, can also activate NOD1 and NOD2. This was demonstrated: 1) by using human embryonic kidney epithelial (HEK) 293 cells transfected with a NF-kappaB reporter plasmid in combination with NOD1 or NOD2 expression plasmids; 2) by inhibiting DMXAA-induced chemokine (CXCL10) mRNA and protein production in the AB12 mesothelioma cell line using a pharmacological inhibitor of RICK kinase, SB20358; and 3) by using small interfering RNA to knock down NOD2 and lentiviral short hairpin RNA to knock down RICK. These findings expand the potential ligands for the NOD-like receptors, suggesting that other xanthone compounds may act similarly and could be developed as anti-tumor agents. This information also expands our knowledge on the mechanisms of action of the anti-tumor agent DMXAA (currently in clinical trials) and may be important for its biological activity.

Helicobacter pylori induces MAPK phosphorylation and AP-1 activation via a NOD1-dependent mechanism.

Helicobacter pylori rapidly activates MAPKs and transcription factors, NF-kappaB and AP-1, in gastric epithelial cells following host attachment. Activation of these signal transducers is largely dependent on the cag pathogenicity island (cagPAI)-encoded Type IV Secretion System. H. pylori was shown to translocate peptidoglycan through the Type IV Secretion System, which is recognized by the pathogen recognition molecule, NOD1, thus resulting in NF-kappaB activation. The mechanisms of H. pylori-induced MAPK and AP-1 activation, however, are less well defined and therefore, we assessed the contribution of NOD1 to their activation. For this, we used gastric epithelial cell lines, stably expressing siRNA to either NOD1 or a control gene. In siNOD1-expressing cells stimulated with cagPAI(+) H. pylori, we observed significant reductions in p38 and ERK phosphorylation (p < 0.05), whereas the levels of Jnk phosphorylation remained unchanged. Consistent with a previous report, however, we were able to demonstrate NOD1-dependent Jnk phosphorylation by the invasive pathogen Shigella flexneri, highlighting pathogen-specific host responses to infection. We also show that NOD1 was essential for H. pylori induction of not only NF-kappaB, but also AP-1 activation, implying that NOD1 induces robust proinflammatory responses, in an attempt to rapidly control infection. Pharmacological inhibition of p38 and ERK activity significantly reduced IL-8 production in response to H. pylori, further emphasizing the importance of MAPKs in innate immune responses to the pathogen. Thus, for the first time we have shown the important role for NOD1 in MAPK and AP-1 activation in response to cagPAI(+) H. pylori.