Disease relevance of Nod2

• Specific mutations of Nod2 have been associated with two inflammatory diseases, Crohn disease and Blau syndrome, and are thought to contribute to disease susceptibility through altering Nod2 signaling [1].
• The unexpected interference of DN Nod1 in the response of macrophages to gram-positive bacteria was confirmed with a Nod2 agonist (muramyl dipeptide) in transfection experiments with HEK293T cell [2].
• We generated cloned murine oviduct epithelial cell lines without viral or chemical transformation to investigate the role of the TLRs and cytosolic nucleotide binding site/leucine-rich repeat proteins Nod1 and Nod2 in epithelial responses to Chlamydia muridarum infection [3].
• METHODS: An analysis of the lethality of Escherichia coli CP9 was conducted in mice that had been depleted of NK cells via the injection of an anti-asialo GM1 antibody and in CD epsilon transgenic mice that are deficient in both NK cells and T cells [4].
• We finally demonstrate that in C57BL/6 mouse lung tissue in vivo as well as in the bronchial epithelial cell line BEAS-2B, Nod1 and Nod2 mRNA expressions were up-regulated after pneumococcal infection [5].

High impact information on Nod2

• Transfection of the mutant act1 allele into wild-type Toxoplasma conferred motility and invasion in the presence of CD [6].
• CD resistance in Toxoplasma was mediated by a point mutation in the single-copy actin gene ACT1 [6].
• In clonogenic assays transfected cells expressing CD were selectively killed by incubation in 5-fluorocytosine, whereas control cell lines were not [7].
• Lysates from these cell populations exhibited significant CD activity detected by conversion of radiolabeled cytosine to uracil [7].
• Mammalian cells, unlike certain bacteria and fungi, do not contain the enzyme CD and do not ordinarily metabolize cytosine to uracil [7].

Chemical compound and disease context of Nod2

• The Escherichia coli CD gene underwent PCR oligonucleotide-directed mutagenesis to enhance its expression in a eukaryotic system and it was then cloned into an expression vector, pLXSN, that also contains a neomycin-resistance gene [7].
• The liposome binding assay shows that interaction of the receptor with spikes on virions at 37 degrees C causes a conformational change that makes the virions hydrophobic so that they bind to liposomes (B. D. Zelus, J. H. Schickli, D. M. Blau, S. R. Weiss, and K. V. Holmes, J. Virol. 77: 830-840, 2003) [8].
• AIM: To construct a Bifidobacterium infantis/CD targeting gene therapy system and observe the antitumor effect of cytosine deaminase/5-fluorocytosine (CD/5-FC) suicide gene therapy system mediated by Bifidobacterium infantis on melanoma in vitro and in vivo [9].

Biological context of Nod2

• Using targeted mutagenesis, we introduced a mutation to delete the CARD domains of mouse Nod2 [10].
• Taken together, these results show the contribution of phagocytosis and Nod molecules to the response to HKSA in macrophages and also identify possible cross talk between Nod1 and Nod2 [2].
• The mouse Nod2 locus is located at chromosome 8 and composed of 12 exons, 11 of which encode the Nod2 protein [11].
• Genetic variation in human Nod2 has been associated with susceptibility to Crohn's disease [11].
• Of the 140 polymorphic sites identified, 68 were located in the coding region, of which 28 created amino acid substitutions in Nod2 [11].

Anatomical context of Nod2

• Nod2 is an intracellular sensor of a specific bacterial cell wall component, muramyl dipeptide, and activation of Nod2 stimulates an inflammatory response [1].
• Induction of Nod1 and Nod2 intracellular pattern recognition receptors in murine osteoblasts following bacterial challenge [12].
• Messenger RNAs for Nod1 and Nod2 were present in the epithelial cell lines [3].
• Cathepsin D (CD) is an aspartyl protease identified in endosomes of APC [13].
• OVA digested in vitro with purified CD was able to stimulate IL-2 secretion by three different OVA-specific I-Ad restricted Th cell hybridomas when it was presented by fixed APC [13].

Associations of Nod2 with chemical compounds

• Among the intracellular sensors is a protein known as Nod2, a cytosolic protein containing a leucine-rich repeat domain [14].
• Thus CD, with its ability to produce the toxic antimetabolite 5-fluorouracil from 5-fluorocytosine, may be useful as a negative selection system for studies and treatments employing gene transfer techniques [7].
• Two protein synthesis inhibitors, cycloheximide and puromycin, blocked the CD-induced increase in beta-actin mRNA, in contrast to the serum-induced increase which is insensitive to inhibitors of protein synthesis [15].
• This increase is apparently controlled at the level of translation, because control and Ac-treated cells contained the same amount of poly-A+ RNA, and neither CD nor Ac altered mRNA levels for beta-casein [16].
• This inhibitory effect of CD was not specific to TNF, because the production of interleukin-1 and prostaglandin E2 were also inhibited [17].

Regulatory relationships of Nod2

• Expression of mouse Nod2 activated NF-kappaB and conferred responsiveness to bacterial components, an activity that was deficient in mutants corresponding to those associated with susceptibility to Crohn's disease [11].
• The depletion of intracellular Nod2 by small interfering RNA blocked MDP-induced up-regulation of RANKL mRNA in osteoblasts [18].

Other interactions of Nod2

• Induction of Nod2 mRNA expression by LPS but not by TNF-alpha in osteoblasts was dependent on TLR4 and MyD88 [18].
• SAND persisted in PAFr(-/-) mice but was partially mitigated in mice lacking cell wall recognition proteins TLR2 and Nod2 and in mice overexpressing interleukin-10 (IL-10) in macrophages [19].
• These studies demonstrate a Nod2-independent mechanism mediated through pore-forming pannexin-1 that is required for intracellular delivery of MDP to the cytosol and caspase-1 activation [20].

Analytical, diagnostic and therapeutic context of Nod2

• Sequence analysis of Nod2 from 45 different strains of Mus musculus and Mus spretus revealed extensive polymorphism involving all exons of Nod2 [11].
• These data suggested that in vivo IL-18 gene transfer could augment the antitumor effects of CD suicide gene therapy through efficient induction of antitumor immunity [21].
• Intact cells were compared with cytoplasts, cells enucleated by centrifugation in the presence of cytochalasin D (CD) [22].
• Antibodies to CD raised in mice specifically bound to intact B. catarrhalis, as determined by flow cytometry analysis [23].
• Furthermore, convalescent sera collected from patients with otitis media due to B. catarrhalis infection were found to be reactive with the CD protein by immunoblotting [23].

References