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The non-major histocompatibility complex quantitative trait locus Cia10 contains a major arthritis gene and regulates disease severity, pannus formation, and joint damage.

OBJECTIVE: To construct rats congenic for the chromosome 2 arthritis-regulatory quantitative trait locus Cia10, originally identified in a (DA x ACI)F(2) intercross rat strain that had been assessed for collagen-induced arthritis (CIA), and to determine the effect of this congenic interval on arthritis severity, joint histologic structure, and cytokine transcription in rats with pristane-induced arthritis (PIA). METHODS: A 52.6-MB interval derived from the ACI (CIA- and PIA-resistant) strain and containing the Cia10 interval was introgressed into the DA (arthritis-susceptible) background through genotype-guided congenic breeding. Homozygous male and female DA.ACI(Cia10) congenic rats were studied for their susceptibility to and severity of PIA, and were compared with same-sex DA rats. Histologic analyses were done on hind paws collected on day 32 following the pristane injection. Levels of interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha) messenger RNA (mRNA) were measured with real-time polymerase chain reaction on synovial tissues from day-32 ankles. RESULTS: Both male and female DA.ACI(Cia10) congenic rats developed a significantly milder form of arthritis, with a 95% and 92% reduction in the arthritis severity index compared with DA male and female controls, respectively (males P < or = 0.001 and females P = 0.003). DA.ACI(Cia10) congenic rat synovial tissue was more likely to preserve its normal histologic architecture, including minimal to no cartilage and bone erosions, synovial hyperplasia, and pannus formation, and reduced numbers of vessels (angiogenesis), when compared with DA synovial tissue. There was a 2.7- and 2.4-fold reduction in the amount of IL-1beta and TNFalpha mRNA, respectively, in the synovial tissue of DA.ACI(Cia10) congenic rats compared with DA rats. Sequencing analyses of complementary DNA for the Cia10-predicted candidate gene Ptpn8, the rat homolog of the rheumatoid arthritis (RA)-susceptibility gene PTPN22, revealed no polymorphisms between the DA and ACI strains. CONCLUSION: This study determined that Cia10 harbors a major autoimmune arthritis-regulatory gene. This gene regulates clinical disease severity, histologic damage, and the levels of at least two central proinflammatory cytokines. We are in the process of narrowing down the critical region for positional cloning of the Cia10 gene. The identification of this gene will provide novel targets or pathways for focused candidate-gene studies in RA.

Animals↗

Identification of novel effectors of invasive cell growth downstream of phosphoinositide 3-kinase.

Conventional approaches to identifying cancer targets are complicated by the chromosomal instability of tumour cells, and typically result in a large number of differentially expressed candidate genes with uncertain disease relevance. Here we present a novel approach which aims to elucidate the molecular changes that are induced after loss of tumour suppressor function. Using gene silencing tools, we mimic the loss of tumour suppressor function to identify key regulators of tumour initiation and progression. Loss of function of the tumour suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10) correlates with increased invasive cell growth due to the resulting chronic activation of the PI 3-kinase (phosphoinositide 3-kinase) pathway. Induced activation of PI 3-kinase either by inhibiting PTEN expression or by using p110*, a constitutively active PI 3-kinase, increased signalling and the invasive growth potential of cells. Using this unbiased approach we have identified novel downstream effectors of PI 3-kinase/PTEN signalling that mediate the behaviour of cells with a hyperactive PI 3-kinase pathway. These molecules represent candidate targets for therapeutic intervention in patients with PTEN-deficient tumours.

Animals↗

HTLV-I proviral DNA in umbilical cord blood of babies born to carrier mothers.

Human T-lymphotropic virus type I (HTLV-I) in cord blood raises the possibility of intrauterine transmission as an alternative pathway to transmission via breast milk. However, none of 7 children with HTLV-I proviral DNA positive cord blood had seroconverted by 24-48 months. Contamination of cord blood by maternal blood was precluded on the basis of viral load and IgA concentration. Thus cord blood proviral DNA is not a hallmark of intrauterine infection. Moreover, none of the cord blood samples of 9 formula-fed children later confirmed to be infected was positive for HTLV-I, indicating that intrauterine infection is not a likely candidate as an alternative pathway.

Breast Feeding↗

Expression of Frizzled genes in developing and postnatal hair follicles.

Embryonic hair follicle development and postnatal hair growth rely on intercellular communication within the epithelium and between epithelial and mesenchymal cells. Several members of the WNT family of paracrine intercellular signaling molecules are expressed in specific subsets of cells in developing and mature mouse hair follicles, suggesting them as candidates for some of the intercellular signals that operate in these organs. As WNT ligands activate several different signaling pathways, they may play multiple and complex roles in developing and postnatal skin. To begin to investigate these functions, we have used in situ hybridization to identify cells that express Frizzled (Fz) WNT receptor genes, and so are potentially receptive to WNT ligands. We find that several Fz genes are specifically expressed at sites of known activity of the WNT/beta-catenin signaling pathway, allowing us to identify candidate receptors for canonical WNT ligands important in appendage development. The expression of additional Fz genes is specifically elevated at locations and developmental stages other than those that display WNT/beta-catenin pathway activity, suggesting that signaling through alternate WNT pathways may contribute to the development and function of skin and hair.

Age Factors↗

No evidence for binding of clozapine, olanzapine and/or haloperidol to selected receptors involved in body weight regulation.

The underlying mechanisms of antipsychotic (AP)-induced weight gain are unknown, but both central and peripheral AP target receptors could potentially be involved. This study used radioligand binding assays to compare the binding affinities of clozapine, olanzapine and haloperidol for candidate receptors potentially involved in AP-induced weight gain. Selected candidates derived from known pathways involved in body weight regulation included receptors classified as anorexigenic (bombesin receptor subtype 3, calcitonin gene-related peptide receptor, cholecystokinin receptor, melanocortin-4 receptor, neurotensin receptor 1) or orexigenic (cannabinoid receptor 1, galanin 1 receptor, melanin-concentrating hormone receptor (MCHR), neuropeptide Y1 receptor) as well as receptors involved in physiological actions related to digestion and fluid homeostasis (angiotensin II type 1 receptor, bradykinin B2 receptor, endothelin receptor, neurokinin 1 receptor, vasoactive intestinal polypeptide receptor 1). Clozapine, olanzapine and haloperidol exhibited negligible affinities to all of these receptors except for the MCHR (Ki=501 nM; haloperidol). With respect to other candidates from (neuro)transmitter systems already suggested to be involved in AP-induced weight gain, the binding profile of olanzapine resembled that of clozapine, with high affinity (Ki<10 nM) for serotonin (5-HT) 5-HT2A, 5-HT2C and 5-HT6, muscarinic M1 and histamine H1 receptors. In contrast, the binding profile of haloperidol was substantially different (high affinity only for the dopamine D1 receptor). In conclusion, we have not identified a novel binding site of the two investigated atypical AP that could contribute to the induced weight gain.

Animals↗

Linkage analysis of a large pedigree with hereditary sideroblastic anaemia.

A large pedigree showing a history of pyridoxine responsive X linked sideroblastic anaemia was screened with several polymorphic DNA markers from the X chromosome. Linkage analysis between each marker and disease status was performed, giving a maximum two point lod score of 3.64 at zero recombination with the microsatellite marker PGK1P1 at Xq11.2-12. Close linkage to PGK at Xq13.3, one of the candidate regions for X linked sideroblastic anaemia, was excluded. Linkage to DNA markers distal to PGK and at Xp21 was also excluded. Multipoint linkage analysis was performed with markers located between Xq11.2-21. The maximum map specific lod score obtained was 3.56 at PGK1P1 (Xq11.2-12). Linkage remained significant over the interval 20 cM proximal to PGK1P1 and 5 cM distal to PGK1P1, with definite exclusion around the PGK locus. The most likely location of the gene involved in sideroblastic anaemia in this pedigree is therefore within the pericentromeric region of the X chromosome. This region includes the erythroid 5-aminolaevulinate synthetase gene of the haem synthesis pathway, which is a candidate gene for X linked sideroblastic anaemia located at Xp11.21.

Alleles↗

[Integrated methods for assessing auditory nerve-auditory pathway integrity].

OBJECTIVE: To evaluate the feasibility and value of integrated methods to assess auditory pathway integrity. METHOD: Twenty-four cases of bilateral profoundly-deafened individuals who were considered as the candidates of cochlear implantation were included in this study. Auditory pathway integrity from these candidates of cochlear implantation were assessed with the integrated methods established by our team, which consist of 5 categories including 1. audiological test; 2. radiological imaging study; 3. ear-canal electric audiometry; 4. response to sound in daily life; and 5. speech development. RESULT: Twenty-three candidates who meet the criteria of auditory nerve-auditory pathway integrity received cochlear implantation with improved hearing and speech development postoperatively. The remainder one of the 24 candidates was diagnosed as bilateral absence of auditory nerve. The fault of cochlear implantation was avoided. CONCLUSION: The integrated methods for assessing auditory pathway integrity is feasible and valuable. Auditory nerve-auditory pathway integrity should be considered and included as one of the most important criteria for cochlear implantation candidate.

Acoustic Stimulation↗

A review of asthma genetics: gene expression studies and recent candidates.

Recent evidence indicates an important role of inflammation pathways, airways remodeling and epithelium activation in asthma genetics. In particular, transcriptome studies have detected differentially expressed genes involved in eosinophil apoptosis, the arginase pathway, response to allergens or interleukins, and to inhaled corticosteroids. Candidate gene and genome wide studies have localized genetic regions involved in the disease, such as the A1AR and CLCA1 genes (chromosome 1), IL-1RN and DPP10 (2q14), HLA-G and TNF-a (6p21), GPRA (7p14), FceRI and GSTP1 (11q13), NOS1, IFNG, STAT6, VDR, and other genes (12q13-26), PHF11 and flanking genes (13q14), AACT and PTGDR (14q), and ADAM33 (20p13). The role of these and other genetic determinants has to be confirmed in future, preferably longitudinal, studies.

Allergens↗

Increased expression of Wnt-1 in schizophrenic brains.

The regulated expression of Wnt-1, one member of the wingless/Wnt pathway, in the brain is critical for many neurodevelopmental processes. Recently, it has been reported that the wingless/Wnt pathway participates in a complex behavioral phenomenon and suggested that this pathway's molecules are candidate genes for neuropsychiatric disorders. Thus, we investigated the expression of Wnt-1 in the hippocampal region, which is believed to be closely involved in the pathophysiology of schizophrenia, of postmortem brains from 10 schizophrenic and 10 control individuals. Immunohistochemical analysis with polyclonal antibodies recognizing Wnt-1 revealed immunoreactivity primarily in the pyramidal cell layer, particularly in CA3 and CA4 regions. We observed a significant elevation in the number of Wnt-1-immunoreactive neurons in the great majority of schizophrenic brains relative to that in controls. The expression of Wnt-1 may be related to cell adhesion, synaptic rearrangement, and plasticity. Therefore, the increase in Wnt-1 immunoreactivity in schizophrenic hippocampi suggests an altered plasticity of this structure in a large proportion of schizophrenic brains. These findings suggest an abnormality of the wingless/Wnt pathway present in the schizophrenic brain and may support the 'neurodevelopmental hypothesis' of schizophrenia.

Aged↗

A role for Pyk2 and Src in linking G-protein-coupled receptors with MAP kinase activation.

The mechanisms by which mitogenic G-protein-coupled receptors activate the MAP kinase signalling pathway are poorly understood. Candidate protein tyrosine kinases that link G-protein-coupled receptors with MAP kinase include Src family kinases, the epidermal growth factor receptor, Lyn and Syk. Here we show that lysophosphatidic acid (LPA) and bradykinin induce tyrosine phosphorylation of Pyk2 and complex formation between Pyk2 and activated Src. Moreover, tyrosine phosphorylation of Pyk2 leads to binding of the SH2 domain of Src to tyrosine 402 of Pyk2 and activation of Src. Transient overexpression of a dominant interfering mutant of Pyk2 or the protein tyrosine kinase Csk reduces LPA- or bradykinin-induced activation of MAP kinase. LPA- or bradykinin-induced MAP kinase activation was also inhibited by overexpression of dominant interfering mutants of Grb2 and Sos. We propose that Pyk2 acts with Src to link Gi- and Gq-coupled receptors with Grb2 and Sos to activate the MAP kinase signalling pathway in PC12 cells.

Animals↗

Inflammatory gene polymorphisms and risk of postoperative myocardial infarction after cardiac surgery.

BACKGROUND: The inflammatory response triggered by cardiac surgery with cardiopulmonary bypass (CPB) is a primary mechanism in the pathogenesis of postoperative myocardial infarction (PMI), a multifactorial disorder with significant inter-patient variability poorly predicted by clinical and procedural factors. We tested the hypothesis that candidate gene polymorphisms in inflammatory pathways contribute to risk of PMI after cardiac surgery. METHODS AND RESULTS: We genotyped 48 polymorphisms from 23 candidate genes in a prospective cohort of 434 patients undergoing elective cardiac surgery with CPB. PMI was defined as creatine kinase-MB isoenzyme level > or = 10x upper limit of normal at 24 hours postoperatively. A 2-step analysis strategy was used: marker selection, followed by model building. To minimize false-positive associations, we adjusted for multiple testing by permutation analysis, Bonferroni correction, and controlling the false discovery rate; 52 patients (12%) experienced PMI. After adjusting for multiple comparisons and clinical risk factors, 3 polymorphisms were found to be independent predictors of PMI (adjusted P<0.05; false discovery rate <10%). These gene variants encode the proinflammatory cytokine interleukin 6 (IL6 -572G>C; odds ratio [OR], 2.47), and 2 adhesion molecules: intercellular adhesion molecule-1 (ICAM1 Lys469Glu; OR, 1.88), and E-selectin (SELE 98G>T; OR, 0.16). The inclusion of genotypic information from these polymorphisms improved prediction models for PMI based on traditional risk factors alone (C-statistic 0.764 versus 0.703). CONCLUSIONS: Functional genetic variants in cytokine and leukocyte-endothelial interaction pathways are independently associated with severity of myonecrosis after cardiac surgery. This may aid in preoperative identification of high-risk cardiac surgical patients and development of novel cardioprotective strategies.

Aged↗

Autonomic brainstem projections to the pancreas: a retrograde transneuronal viral tracing study in the rat.

The present study describes brainstem nuclei that participate in the autonomic innervation of the pancreas, using a retrograde viral transneuronal tracing technique. It aimed at identifying the neuronal architecture of the parasympathetic, gustatory-induced insulin release by the endocrine pancreas (preabsorptive insulin response, PIR). Autonomic pathways organized for reflex adjustments of the end organ, as it happens in the PIR, involve relatively simple circuits. This implies a short brainstem circuit from the rostral gustatory nucleus of the solitary tract to the dorsal motor nucleus of the vagus. The present findings confirm projections to the pancreas, originating from preganglionic neurons in the dorsal motor nucleus of the vagus. Transneuronal labeling was detected in the medial, and to a lesser extent in the lateral nucleus of the solitary tract mainly at caudal and intermediate levels. Furthermore, infected neurons were seen in the brainstem in the dorsal and ventral part of the medullary reticular formation, in the area postrema and in the raphe nuclei. Sparse labeling was found in the gustatory zone of the nucleus tractus solitarius. These results indicate that a direct connection between the rostral nucleus tractus solitarius and the medial dorsal motor nucleus of the vagus is very unlikely, so that one or more intermediate stations may be involved. Candidates to complete this pathway are the intermediate or caudal nucleus tractus solitarius, the medullary reticular formation or the parabrachial nucleus.

Animals↗

Germline mutations but not somatic changes at the MYH locus contribute to the pathogenesis of unselected colorectal cancers.

MYH-associated polyposis is a recently described, autosomal recessive condition comprising multiple colorectal adenomas and cancer. This disease is caused by germline mutations in the base excision repair (BER) gene MYH. Genes involved in the BER pathway are thus good candidates for involvement in the pathogenesis of sporadic tumors of the large bowel. We have screened a set of 75 sporadic colorectal cancers for mutations in MYH, MTH1, and OGG1. Allelic loss at MYH was also assessed. Selected samples were screened for mutations and allele loss at APC and mutations in p53, K-ras, and beta-catenin. A panel of 35 colorectal cancer cell lines was screened for MYH mRNA and protein expression. One of 75 cancers had bi-allelic germline mutations in MYH and on retrospective analysis of medical records this patient was found to have synchronous multiple small adenomas in addition to carcinoma. No somatic MYH mutations were found and mRNA and protein were expressed in all of our cell lines. There were no clearly pathogenic mutations in MTH1 or OGG1 in any tumor. Bi-allelic germline MYH mutations cause approximately 1 to 3% of unselected colorectal cancers, but appear always to be associated with multiple adenomas. Somatic inactivation of the DNA glycosylases involved in the BER pathway however does not appear to be involved in colorectal tumorigenesis.

Adenoma↗

Herbivore-induced volatile production by Arabidopsis thaliana leads to attraction of the parasitoid Cotesia rubecula: chemical, behavioral, and gene-expression analysis.

Many plant species defend themselves against herbivorous insects indirectly by producing volatiles in response to herbivory. These volatiles attract carnivorous enemies of the herbivores. Research on the model plant Arabidopsis thaliana (L.) Heynh. has contributed considerably to the unraveling of signal transduction pathways involved in direct plant defense mechanisms against pathogens. Here, we demonstrate that Arabidopsis is also a good candidate for studying signal transduction pathways involved in indirect defense mechanisms by showing that: (1) Adult females of Cotesia rubecula, a specialist parasitic wasp of Pieris rapae caterpillars, are attracted to P. rapae-infested Arabidopsis plants. (2) Arabidopsis infested by P. rapae emits volatiles from several major biosynthetic pathways, including terpenoids and green leaf volatiles. The blends from herbivore-infested and artificially damaged plants are similar. However, differences can be found with respect to a few components of the blend, such as two nitriles and the monoterpene myrcene, that were produced exclusively by caterpillar-infested plants, and methyl salicylate, that was produced in larger amounts by caterpillar-infested plants. (3) Genes from major biosynthetic pathways involved in volatile production are induced by caterpillar feeding. These include AtTPS10, encoding a terpene synthase involved in myrcene production, AtPAL1, encoding phenylalanine ammonia-lyase involved in methyl salicylate production, and AtLOX2 and AtHPL, encoding lipoxygenase and hydroperoxide lyase, respectively, both involved in the production of green leaf volatiles. AtAOS, encoding allene oxide synthase, involved in the production of jasmonic acid, also was induced by herbivory.

Adaptation, Physiological↗

Molecular and electrophysiological characterization of transient receptor potential ion channels in the primary murine megakaryocyte.

The molecular identity of platelet Ca(2+) entry pathways is controversial. Furthermore, the extent to which Ca(2+)-permeable ion channels are functional in these tiny, anucleate cells is difficult to assess by direct electrophysiological measurements. Recent work has highlighted how the primary megakaryocyte represents a bona fide surrogate for studies of platelet signalling, including patch clamp recordings of ionic conductances. We have now screened for all known members of the transient receptor potential (TRP) family of non-selective cation channels in murine megakaryocytes following individual selection of these rare marrow cells using glass micropipettes. RT-PCR detected messages for TRPC6 and TRPC1, which have been reported in platelets and megakaryocytic cell lines, and TRPM1, TRPM2 and TRPM7, which to date have not been demonstrated in cells of megakaryocytic/platelet lineage. Electrophysiological recordings demonstrated the presence of functional TRPM7, a constitutively active cation channel sensitive to intracellular Mg(2+), and TRPM2, an ADP-ribose-dependent cation channel activated by oxidative stress. In addition, the electrophysiological and pharmacological properties of the non-selective cation channels stimulated by the physiological agonist ADP are consistent with a major role for TRPC6 in this G-protein-coupled receptor-dependent Ca(2+) influx pathway. This study defines for the first time the principal TRP channels within the primary megakaryocyte, which represent candidates for Ca(2+) influx pathways activated by a diverse range of stimuli in the platelet and megakaryocyte.

Animals↗

Genome-Wide Association Analysis for Growth-Related Traits in Indoor- and Outdoor-Cultured Juvenile Grass Carp (Ctenopharyngodon idella).

Grass carp is a key herbivorous freshwater fish, yet long-term inbreeding reduces growth rates. Current genome-wide association studies (GWAS) primarily focus on a limited range of growth traits, while intestinal morphology is likely to emerge as a promising new proxy for both growth performance and health status. We reared juvenile grass carp from one batch in indoor vs. natural aquatic vegetation groups for 100 days, measuring body weight (BW), length (BL), height (BH), and intestinal length (IL) in 200 individuals (100/group). Phenotypic differences were significant for all traits, with IL most variable. GWAS identified 95 significant SNPs, among which 21 were related to multiple traits. Candidate gene and KEGG pathway analyses linked these SNPs to myogenesis, skeletal development, immunity, calcium signaling, and stress resistance. Twelve SNPs were found to be associated with IL, including 8 multi-trait-related and 4 trait-specific ones. This suggests that IL can serve as a supplementary growth trait. There was no overlap with prior GWAS, but recurrent signals on chromosomes 1, 2, 14 (BW) and 2, 3, 14, 24 (BH) merit further study. Our findings enrich molecular resources for grass carp and highlight IL's potential for marker-assisted breeding.

Ctenopharyngodon idella↗

Mechanism of action of serotonin selective reuptake inhibitors. Serotonin receptors and pathways mediate therapeutic effects and side effects.

Serotonin selective reuptake inhibitors (SSRIs) are currently among the most frequently prescribed therapeutic agents in all of medicine. Their therapeutic actions are diverse, ranging from efficacy in depression to obsessive-compulsive disorder, panic disorder, bulimia and other conditions as well. The plethora of biological substrates, receptors and pathways for serotonin are candidates to mediate not only the therapeutic actions of SSRIs, but also their side effects. Specifically, the immediate actions of SSRIs are mostly side effects, and may be mediated by the initiating actions of SSRIs, namely negative allosteric modulation of the serotonin transporter. A leading hypothesis to explain these immediate side effects is that serotonin is increased at specific serotonin receptor subtypes in discrete regions of the body where the relevant physiologic processes are regulated. Desensitization of post-synaptic receptors in these same discrete brain regions may explain the development of tolerance to these same side effects. The explanation for therapeutic effects characteristic of SSRIs may be found in delayed neurochemical adaptations. A leading hypothesis for this action is desensitization of somatodendritic serotonin 1A autoreceptors in the midbrain raphe. The hypothesis to explain why SSRIs have such diverse therapeutic actions is that somatodendritic 5HT1A autoreceptor desensitization increases serotonin in those critical brain regions and at those key serotonin receptor subtype(s) which may mediate the pathophysiologies of the various disorders. Understanding the topography of serotonin receptor subtypes in discrete anatomical pathways may enhance our understanding of both the therapeutic actions and side effects of these important pharmaceutical agents.

Autoreceptors↗

Nonselective cation conductance activated by muscarinic and purinergic receptors in rat spiral ganglion neurons.

The present study characterizes the ionic conductances activated by acetylcholine (ACh) and ATP, two candidate neuromodulators, in isolated spiral ganglion neurons (SGNs). Brief application (1 s) of ACh evoked in a dose-dependent manner (EC(50) = 4.1 microM) a reversible inward current with a long latency (average 1.3 s), at holding potential (V(h)) = -50 mV. This current was reversibly blocked by atropine and mimicked by muscarine. Application of ATP also evoked a reversible inward current at V(h) = -50 mV, but the current showed two components. A fast component with a short latency was largely reduced when N-methyl-D-glucamine (NMDG) replaced extracellular sodium, implying a P2X-like ionotropic conductance. The second component had a longer latency (average 1.1 s) and was presumably activated by metabotropic P2Y-like receptors. The second component of ATP-evoked current shared similar characteristics with the responses evoked by ACh: the current reversed near 0 mV, displayed inward rectification, could be carried by NMDG, and was insensitive to extracellular and intracellular calcium. This ACh-/ATP-evoked conductance was reversibly inhibited by preapplication of ionomycin. These results suggest that muscarinic receptors and purinergic metabotropic receptors activate a similar large nonselective cation conductance via a common intracellular pathway in SGNs, a candidate mechanism to regulate neuronal excitability of SGNs.

Acetylcholine↗