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PubMed2005

Identification of V23RalA-Ser194 as a critical mediator for Aurora-A-induced cellular motility and transformation by small pool expression screening.

Human Aurora kinases have three gene family members: Aurora-A, Aurora-B, and Aurora-C. It is not yet established what the specificity of these kinases are and what signals relayed by their reactions. Therefore, we employed small pool expression screening to search for downstream substrates of Aurora-A. Interestingly, all of the identified Aurora-A substrates were resistant to serve as substrates for Aurora-B or Aurora-C, suggesting that these Aurora family members may have distinct substrate specificity for propagation of diverse signaling pathways, even though they share a conserved catalytic kinase domain. Of the candidate substrates, Aurora-A could increase the functional activity of RalA. Mutational analysis revealed that RalA-Ser194 was the phosphorylation site for Aurora-A. Ectopic expression of V23RalA-WT could enhance collagen I-induced cell migration and anchorage-independent growth in Madin-Darby canine kidney (MDCK) Aurora-A stable cell lines. In contrast, overexpression of V23RalA-S194A in MDCK Aurora-A-stable cell lines abolished the intrinsic migration and transformation abilities of Aurora-A. To our knowledge, this is the first systematic search for the downstream substrates of Aurora-A kinase. Moreover, these results support the notion that Aurora-A may act in concert with V23RalA through protein phosphorylation on Ser194 to promote collagen I-induced cell motility and anchorage-independent growth in MDCK epithelial cells.

Amino Acid Sequence↗

PubMed1999

Phosphorylation of Tyr319 in ZAP-70 is required for T-cell antigen receptor-dependent phospholipase C-gamma1 and Ras activation.

Accumulating evidence indicates that the interdomain B regions of ZAP-70 and Syk play pivotal roles in the coupling of T-cell antigen receptor (TCR) stimulation to the activation of downstream signaling pathways. The interdomain B region of ZAP-70 contains at least three candidate sites of tyrosine phosphorylation. In this report, we identify Tyr319 as a functionally important phosphorylation site in the ZAP-70 interdomain B region. TCR crosslinkage triggered a rapid increase in the phosphorylation of Tyr319 in Jurkat T cells. Although mutation of Tyr319 to Phe had no effect on the tyrosine kinase activity of ZAP-70, the resulting ZAP(Y319-->F) mutant failed to reconstitute TCR-dependent Ca2+ mobilization, Ras activation, CD69 expression and NFAT-dependent transcription in ZAP-70-deficient Jurkat cells. These defects were correlated with reduced tyrosine phosphorylation of phospholipase C (PLC)-gamma1 and the LAT adapter protein in the ZAP(Y319-->F)-expressing cells. On the other hand, ZAP(Y319-->F)-expressing cells displayed normal increases in SLP-76 phosphorylation and ERK activation during TCR stimulation. Phosphorylation of Tyr319 promoted the association of ZAP-70 with the SH2 domains of two key signaling molecules, Lck and PLC-gamma1. These studies suggest that Tyr319 phosphorylation is required for the assembly of a ZAP-70-containing signaling complex that leads to the activation of the PLC-gamma1- and Ras-dependent signaling cascades in antigen-stimulated T cells.

Adaptor Proteins, Signal Transducing↗

PubMed1985

Altered fidelity of mitotic chromosome transmission in cell cycle mutants of S. cerevisiae.

Thirteen of 14 temperature-sensitive mutants deficient in successive steps of mitotic chromosome transmission (cdc2, 4, 5, 6, 7, 8, 9, 13, 14, 15, 16, 17 and 20) from spindle pole body separation to a late stage of nuclear division exhibited a dramatic increase in the frequency of chromosome loss and/or mitotic recombination when they were grown at their maximum permissive temperatures. The increase in chromosome loss and/or recombination is likely to be due to the deficiency of functional gene product rather than to an aberrant function of the mutant gene product since the mutant alleles are, with one exception, recessive to the wild-type allele for this phenotype. The generality of this result suggests that a delay in almost any stage of chromosome replication or segregation leads to a decrease in the fidelity of mitotic chromosome transmission. In contrast, temperature-sensitive mutants defective in the control step of the cell cycle (cdc28), in cytokinesis (cdc3) or in protein synthesis (ils1) did not exhibit increased recombination or chromosome loss.--Based upon previous results with mutants and DNA-damaging agents in a variety of organisms, we suggest that the induction of mitotic recombination in certain mutants is due to the action of a repair pathway upon nicks or gaps left in the DNA. This interpretation is supported by the fact that the induced recombination is dependent upon the RAD52 gene product, as essential component in the recombinogenic DNA repair pathway. Gene products whose deficiency leads to induced recombination are, therefore, strong candidates for proteins that function in DNA metabolism. Among the mutants that induce recombination are those known to be defective in some aspect of DNA replication (cdc2, 6, 8, 9) as well as some mutants defective in the G2 (cdc13 and 17) and M (cdc5 and 14) phases of the mitotic cycle. We suggest that special aspects of DNA metabolism may be occurring in G2 and M in order to prepare the chromosomes for proper segregation.

Cell Cycle↗

PubMed2006

The G72/G30 gene locus in psychiatric disorders: a challenge to diagnostic boundaries?

In follow-up from evidence obtained in linkage studies, systematic linkage disequilibrium mapping within chromosomal region 13q33 has led to the identification of a schizophrenia susceptibility locus which harbors the genes G72 and G30. These association findings have been replicated in several independent schizophrenia samples. Association has also been found between genetic variants at the G72/G30 locus and bipolar affective disorder (BPAD), with replication in independent studies. Results from studies of more detailed psychiatric phenotypes show that association exists with symptom clusters that are common to several disorders as well as with specific psychiatric diagnoses. These findings may indicate that the association lies not with the diagnostic categories per se but with more specific aspects of the phenotype, such as affective symptoms and cognitive effects, which cross traditional psychiatric diagnostic boundaries. At the molecular level, the picture remains far from clear. No putative functional variants have been identified in the coding regions of G72 or G30, and it is therefore likely that disease susceptibility is caused by as yet unidentified variants which alter gene expression or splicing. A further complication is the fact that inconsistencies are evident in the risk alleles and haplotypes observed to be associated across different samples and studies, which may suggest the presence of multiple susceptibility variants at this locus. Functional analyses indicate that the G72 gene product plays a role in the activation of N-methyl-D-aspartate receptors, a molecular pathway implicated in both schizophrenia and BPAD, making it the most plausible candidate gene at this locus.

Bipolar Disorder↗

PubMed2006

The possible role of myostatin in skeletal muscle atrophy and cachexia.

The presence of sufficient skeletal muscle is of paramount importance for body function. Cachexia can be defined as a wasting syndrome describing the progressive loss of both adipose and skeletal muscle tissue in concert with severe injury, chronic or end-stage malignant and infectious diseases. Generally, cachexia predisposes to poor prognosis, co-morbidities and death. One signaling pathway possibly involved in muscle atrophy and cachexia is the myostatin cascade. This transforming growth factor-beta superfamily member myostatin is a strong candidate for regulating muscle mass, and is shown to inhibit muscle growth in different in vivo mammalian models. Overall, the modulation of the myostatin pathway seems interesting from the perspective of both pathology and sports medicine. Hence, myostatin signaling components and post-translational modulators are possible targets of pharmacological and other treatments against muscle loss, thus potentially contributing to the understanding and mitigation of muscle atrophies associated with inactivity, senescence and disease.

Animals↗

PubMed2006

Genome-wide analysis of light sensing in Prochlorococcus.

Prochlorococcus MED4 has, with a total of only 1,716 annotated protein-coding genes, the most compact genome of a free-living photoautotroph. Although light quality and quantity play an important role in regulating the growth rate of this organism in its natural habitat, the majority of known light-sensing proteins are absent from its genome. To explore the potential for light sensing in this phototroph, we measured its global gene expression pattern in response to different light qualities and quantities by using high-density Affymetrix microarrays. Though seven different conditions were tested, only blue light elicited a strong response. In addition, hierarchical clustering revealed that the responses to high white light and blue light were very similar and different from that of the lower-intensity white light, suggesting that the actual sensing of high light is mediated via a blue-light receptor. Bacterial cryptochromes seem to be good candidates for the blue-light sensors. The existence of a signaling pathway for the redox state of the photosynthetic electron transport chain was suggested by the presence of genes that responded similarly to red and blue light as well as genes that responded to the addition of DCMU [3-(3,4-dichlorophenyl)-1,1-N-N'-dimethylurea], a specific inhibitor of photosystem II-mediated electron transport.

Bacterial Proteins↗

PubMed2003

NO enhances presynaptic currents during cerebellar mossy fiber-granule cell LTP.

Nitric oxide (NO) is a candidate retrograde messenger in long-term potentiation (LTP). The NO metabolic pathway is expressed in the cerebellar granule cell layer but its physiological role remained unknown. In this paper we have investigated the role of NO in cerebellar mossy fiber-granule cell LTP, which has postsynaptic N-methyl-d-aspartate (NMDA) receptor-dependent induction. Pre- and postsynaptic current changes were simultaneously measured by using extracellular focal recordings, and NO release was monitored with an electrochemical probe in P21 rat cerebellar slices. High-frequency mossy fiber stimulation induced LTP and caused a significant NO release (6.2 +/- 2.8 nM; n = 5) in the granular layer that was dependent on NMDA receptor as well as on nitric oxide synthase (NOS) activation. Preventing NO production by perfusing the NOS inhibitor 100 microM NG-nitro-l-arginine (L-NNA), blocking extracellular NO diffusion by 10 microM MbO2, or inhibiting the NO target guanylyl cyclase (sGC) with 10 microM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-dione (ODQ) prevented LTP. Moreover, the NO donor 10 microM 2-(N,N-diethylamino)-diazenolate-2-oxide.Na (DEA-NO) induced LTP, which was mutually occlusive with LTP generated by high-frequency stimulation, prevented by ODQ, and insensitive to NMDA channel blockade (50 microM APV + 25 microM 7-Cl-kyn) or interruption of mossy fiber stimulation. Thus NO is critical for LTP induction at the cerebellar mossy fiber-granule cell relay. Interestingly, LTP manipulations were accompanied by consensual changes in the presynaptic current, suggesting that NO acts as a retrograde signal-enhancing presynaptic terminal excitability.

Animals↗

PubMed2006

Physiological genomics of cardiac disease: quantitative relationships between gene expression and left ventricular hypertrophy.

The pathogenesis of cardiac left ventricular hypertrophy and failure is poorly defined due to the complexity of the disease phenotype. To gain a better understanding of the relationship between gene expression and left ventricular hypertrophy, we employed a quantitative approach to identify genes with expression patterns that correlate in a numerically continuous manner with parameters of cardiac structure and function in a mouse model of left ventricular hypertrophy due to transverse aortic constriction. Several genes showed expression patterns that were significantly correlated (Pearson's correlation coefficient) with measurements of left ventricular weight, left ventricular wall thickness, and diastolic dimension. We validated our findings in two independent data sets and in a small subset of genes by real-time RT-PCR. Of genes with significant correlations to numerically continuous measurements of hypertrophy, we found enrichment for genes encoding extracellular matrix, growth-related and secreted proteins in the directly correlated subset, and for genes encoding mitochondria and metabolic/fatty acid oxidation proteins in the inversely correlated subset. The results of this filtering strategy suggest that this subset of transcripts with quantitative relationships between gene expression and left ventricular hypertrophy represents potentially important pathways that contribute to the progression to heart failure and are thus candidates for follow-up and functional analysis.

Animals↗

PubMed2006

Identification of transcriptional targets during pancreatic growth after partial pancreatectomy and exendin-4 treatment.

After partial pancreatectomy (Ppx), substantial regeneration of the endocrine and exocrine pancreatic compartments has been shown in adult rodents. Exendin-4 (Ex-4) is a glucagon-like peptide-1 receptor agonist that augments endocrine beta-cell mass by stimulating neogenesis, proliferation, and cell survival. After Ppx, treatment with Ex-4 ameliorates hyperglycemia by stimulating beta-cell mass recovery. We utilized a cDNA microarray approach to identify genes differentially regulated during pancreatic regeneration after Ppx and/or Ex-4 administration. The pancreatic remnant after Ppx showed a large number of differentially regulated genes. In contrast, Ex-4 treatment resulted in a smaller number of differentially regulated genes. Of note, a common subset of genes regulated by Ex-4 and after Ppx was identified, including three members of the mitogenic Reg gene family, Reg2, -3gamma, and -3beta, as well as fragilis, a gene that maintains pluripotency during germ cell specification, and Serpin b1a, a member of an intracellular protease inhibitor family involved in cell survival. These observations were confirmed by real-time PCR. We determined that Reg3beta protein is also induced in the acinar pancreas after Ppx, suggesting a novel role for this factor in pancreatic growth or response to injury. Finally, comparison of transcription factor-binding sites present in the proximal promoters of these genes identified potential common transcription factors that may regulate these genes. Chromatin immunoprecipitation analyses confirmed Reg3gamma as a novel transcriptional target of Foxa2 (HNF3beta). Our data suggest molecular pathways that may regulate pancreatic growth and offer a unique set of candidate genes to target in the development of therapies aimed at improving pancreatic growth and function.

Animals↗

PubMed2006

Lung cancer genetics and pharmacogenomics.

Epidermal growth factor receptor (EGFR)-targeted therapies have demonstrated remarkable success in a small subset of non-small cell lung cancer patients. The mechanism of response has been an area of active research, with somatic mutation in a number of genes in the EGFR signal transduction pathway and copy number alterations of genes of the EGFR family as candidates contributing towards response. Continuing studies should help determine an appropriate biomarker or combination of biomarkers that can be used to predict response to this class of therapy.

Antineoplastic Agents↗

PubMed2002

Selective cytotoxicity evaluation in anticancer drug screening of fractionated plant extracts.

Chosen to reflect biodiversity in a phylogenetic sense, 100 fractionated plant extracts were screened in vitro for cytotoxicity following extraction and fractionation (polypeptide isolation). Of these 100 extracts, 30 were selected and then characterized preliminarily for antitumor potency and mode of action by testing them on two cell lines and primary cultures of human tumor cells. On the basis of cytotoxicity potency, 10 of the extracts were further characterized for anticancer activity in 10 human tumor cell lines. This final testing resulted in seven potential lead plants with superior evidence of antitumor potential: Colchicum autumnale L. (Colchicaceae), Digitalis lanata Ehrh. and Digitalis purpurea L. (Plantaginaceae), Helleborus cyclophyllus Boiss. (Ranunculaceae), Menyanthes trifoliata L. (Menyanthaceae), and Viola arvensis Murr. and Viola patrinii Ging. (Violaceae). Within a database of antitumor compounds, the activity profiles of the extracts from these seven plants were compared, by correlation analysis, with those of more than 100 other compounds, including 39 standard drugs from different classes of cytotoxic mechanisms. The activity profiles of six of these candidates were uncorrelated with those of the standard drugs, possibly indicating new pathways of drug-mediated cell death.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Glucagon-like peptide-1 in the pathogenesis of obesity.

The recently discovered gut peptide glucagon-like peptide-1 (GLP-1) is one of many peptides implicated in the short-term regulation of appetite. GLP-1 is a 30-amino-acid peptide that is produced in and secreted from the L cells of the intestinal mucosa after intake of a mixed meal. The amino acid sequence of GLP-1 is highly conserved and all mammals studied to date have identical GLP-1 sequences. GLP-1 receptors have been found in the lung and stomach, and binding of GLP-1 to skeletal muscle and fat cells has been demonstrated. At physiological plasma levels GLP-1 inhibits meal- and pentagastrin-induced gastric acid secretion. In addition, gastric emptying is delayed. Plasma GLP-1 is acutely elevated in normal-weight subjects after a meal, but obese subjects seem to have an attenuated GLP-1 release in response to meals. Consequently, GLP-1 may be a candidate for meal termination and intermeal satiety by either peripheral or central pathways. In terms of the importance of GLP-1 in the pathogenesis of obesity, research points in the direction of a vicious circle where overfeeding results in a down-regulation of postprandial GLP-1 release, which may result in the consumption of a larger amount of calories to elicit a "normal" GLP-1 satiety signal, thus perpetuating the obese state.

Journal Article↗

PubMed2002

Genetic predictors of therapeutic response to clozapine: current status of research.

Clozapine is one of the most clinically potent drugs currently available for treating the symptoms of schizophrenia. Compared with conventional antipsychotics it surpasses its predecessors in its ability to treat a wider range of symptoms in otherwise refractory patients, while possessing a low propensity to produce extrapyramidal symptoms. Despite its significant advantages, not all patients benefit from treatment. Some patients react adversely to therapy while others fail to respond adequately. If those most likely to benefit from clozapine could be identified prior to treatment, this would significantly improve the clinical management of these patients. Genetic alterations in drug-metabolising enzymes have previously been demonstrated to influence the efficacy of clinically relevant drugs. It is possible that similar alterations in these and other systems may influence the response variability of patients to clozapine. Pharmacogenetic studies are at present investigating genes encoding drug receptors, drug-metabolising enzymes and neurotransmitter transporters to identify genetic variants that may be important. To date polymorphisms within serotonergic and dopaminergic pathways have been implicated, though the involvement of similar variants in other candidate systems is also likely. This information will ultimately enable the genetic prediction of patients most likely to benefit from the drug, and in the process would alleviate the unnecessary exposure of predisposed individuals to potentially serious adverse effects.

Antipsychotic Agents↗

PubMed2005

Signaling processes in tumoral neuroendocrine pituitary cells as potential targets for therapeutic drugs.

Pituitary adenomas are neuroendocrine tumors that produce different endocrine and metabolic alterations, including hyperprolactinemia, acromegaly and Cushing's disease. These different clinical features of pituitary tumors are the result of the overproduction of hormones produced by the different pituitary cell types. Recent advances in the understanding of the signaling pathways that control hormone production in pituitary cells provide a source of potential therapeutic targets. In ACTH-secreting cells, the mechanisms that control hormone biosynthesis have been clarified to a great extent, indicating a number of protein kinases and ligand-activated nuclear receptors as targets for experimental drugs. ACTH production requires the activation of signal transduction through the PKA, the MAPK and the CamK pathways. These pathways activate nuclear receptors, including Nur and PPAR gamma. The inhibition of these kinases and nuclear receptors has been shown to produce therapeutic effects in mouse models of Cushing's syndrome. On the other hand, the signaling pathways that control prolactin and growth hormone production also have potential targets. It has been recently shown that SMAD proteins activated by growth factors of the TGF beta and BMP family interact with estrogen receptors to stimulate the proliferation of prolactin and growth hormone-secreting cells. Cytokines that bind to the membrane protein gp130 also stimulate the proliferation of these cells. The inhibition of both of these pathways results in the decrease of tumor growth in animal models of prolactinoma. Therefore, the study of signaling pathways that control hormone production and proliferation is a good source of candidate targets in pituitary tumors.

Adrenocorticotropic Hormone↗

PubMed2002

Human resistin gene, obesity, and type 2 diabetes: mutation analysis and population study.

The hormone resistin has been suggested to link obesity to type 2 diabetes by modulating steps in the insulin-signaling pathway and inducing insulin resistance. Thus, the resistin gene represents a potential candidate for the etiology of insulin resistance and type 2 diabetes. In this study, we analyzed the coding sequence of the three exons of the resistin gene, together with its 5' regulatory region and 3' untranslated region (UTR), by single-strand conformation polymorphism (SSCP) in 58 type 2 diabetic subjects, 59 obese subjects, and 60 normal subjects. Only one sequence variant was detected in the resistin gene. Sequencing of this variant revealed the presence of a single nucleotide substitution (SNP) in the 3'-UTR of exon 3 (G1326A) [corrected]. Because 3'-UTR SNPs have been shown to affect gene expression, we examined the frequency of this SNP in 591 subjects (198 obese subjects, 207 diabetic subjects, and 186 control subjects) by PCR amplification and BseRI digestion. No significant association was found between the G1326A [corrected] variant and diabetes and obesity. Comparison of clinical and metabolic parameters between G1326A [corrected] carriers and noncarriers again showed no significant difference. In conclusion, our data suggest that genetic defects of the resistin gene are unlikely to play a role in the etiology of these common disorders in our population.

3' Untranslated Regions↗

PubMed2026

Shielding the First 24 Postnatal Months of Life: A Proposal for a Prospective Cohort Study of Early-Life Electromagnetic Exposure and Autism Risk.

BACKGROUND: Autism Spectrum Disorder (ASD) involves Mirror Neuron System (MNS) dysfunction, driving core social and imitative impairments. Systemic physiological alterations such as autonomic dysregulation, mitochondrial dysfunction and neuroinflammation are known to impair synchronization and plasticity of neuronal clusters. A less-evident environmental cofactor, coinciding with rising ASD prevalence, is the considerable world-wide increase in electromagnetic radiation (EMR) overall exposure among children. Experimental evidence shows how low-intensity EMR influences cellular processes, via voltage-gated calcium channels (VGCCs), oxidative stress, and mitochondrial metabolism. The Resonant Convergence framework, allow to predict how chronic EMR exposure during the first 24 postnatal months of life can act as a factor in ASD pathogenesis. The best candidate mechanism is chronic Ion Cyclotron Resonance (ICR) detuning the Ca2+-calmodulin pathway, thus disrupting MNS synchronization. METHODS AND ANALYSIS: A prospective observational pilot cohort study (24-month follow-up) proposes to enroll 1000 full-term newborns into two arms: an EMR-reduced cohort (n = 500, rest and sleep-phase Faraday shielding) and a standard exposure cohort (n = 500). Exposure is quantified via radiofrequency (RF)/extremely low frequency(ELF) measurements, proximity analysis, device inventories and wearable dosimetry. The primary endpoint is a continuous neurodevelopmental trajectory score (joint attention, language, electroencephalogram (EEG) mu-rhythm); binary ASD diagnosis (Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), Autism Diagnostic Interview-Revised (ADI-R)) is a secondary, exploratory endpoint. Moreover, an optional genomic screening will evaluate gene-environment interactions within extremely low-frequency electromagnetic field (ELF-EMF) vulnerable pathways, including ASD-associated genes upregulated by RF via bromodomain and extraterminal protein (BET)-mediated epigenetic mechanisms. Analyses will employ risk ratios, Fisher's exact tests and logistic regression adjusted for confounders; mixed-effects and Bayesian modeling will evaluate longitudinal outcomes and exposure reduction effects. Given a 2-3% baseline prevalence, approximately 20-30 ASD cases are expected. The study is therefore powered for exploratory signal detection rather than definitive causal inference, providing the critical baseline data required to justify and design future confirmatory trials. Sex-stratified modeling will address the 4:1 male-to-female prevalence ratio. ETHICS AND DISSEMINATION: Ethics committee approval is not yet sought; full protocol review and approval will be obtained prior to the study initiation, in strict accordance with the Declaration of Helsinki. Written parental informed consent will be mandatory for all participants prior to enrollment. Study findings and methodological milestones will be disseminated through peer-reviewed international scientific publications. This protocol provides a structured methodological framework for the first prospective investigation of sleep-phase EMR reduction as a potential modulator of ASD incidence during early neurodevelopment. Results will inform adequately powered confirmatory trials in electromagnetic neurodevelopmental epidemiology.

autism spectrum disorder↗

PubMed2000

Immortalized myeloid suppressor cells trigger apoptosis in antigen-activated T lymphocytes.

We described a generalized suppression of CTL anamnestic responses that occurred in mice bearing large tumor nodules or immunized with powerful recombinant viral immunogens. Immune suppression entirely depended on GM-CSF-driven accumulation of CD11b(+)/Gr-1(+) myeloid suppressor cells (MSC) in secondary lymphoid organs. To further investigate the nature and properties of MSC, we immortalized CD11b(+)/Gr-1(+) cells isolated from the spleens of immunosuppressed mice, using a retrovirus encoding the v-myc and v-raf oncogenes. Immortalized cells expressed monocyte/macrophage markers (CD11b, F4/80, CD86, CD11c), but they differed from previously characterized macrophage lines in their capacities to inhibit T lymphocyte activation. Two MSC lines, MSC-1 and MSC-2, were selected based upon their abilities to inhibit Ag-specific proliferative and functional CTL responses. MSC-1 line was constitutively inhibitory, while suppressive functions of MSC-2 line were stimulated by exposure to the cytokine IL-4. Both MSC lines triggered the apoptotic cascade in Ag-activated T lymphocytes by a mechanism requiring cell-cell contact. Some well-known membrane molecules involved in the activation of apoptotic pathways (e.g., TNF-related apoptosis-inducing ligand, Fas ligand, TNF-alpha) were ruled out as candidate effectors for the suppression mechanism. The immortalized myeloid lines represent a novel, useful tool to shed light on the molecules involved in the differentiation of myeloid-related suppressors as well as in the inhibitory pathway they use to control T lymphocyte activation.

3T3 Cells↗

PubMed2001

Two novel quantitative trait loci on mouse chromosomes 6 and 4 independently and synergistically regulate plasma apoB levels.

An elevated plasma apolipoprotein B (apoB) level is a strong predictor of atherosclerosis and coronary heart disease. Epidemiologic and family linkage studies have suggested a genetic basis for the wide variations of plasma apoB levels in the general population. Using a human apoB transgenic (HuBTg) mouse model, we have previously shown that hepatic apoB-100 secretion is a major determinant of the high and low plasma human apoB levels in HuBTg mice of the C57BL/6 (B6) and 129/Sv (129) strains, respectively. In the present article, we present the identification of two novel quantitative trait loci (QTL) as major regulators of plasma human apoB levels in the F(2) and N(2) (backcrossed) offspring (n = 572) derived from crosses between the B6 and 129 mouse strains. These loci were designated ApoB regulator genes (Abrg), because the gene products are likely to be involved in the regulation of plasma apoB levels either directly or indirectly. The first locus, designated Abrg1, was mapped to chromosome 6 in 8-week-old male and female mice with a combined logarithm of odds ratio (LOD) score of 14 at the D6Mit55 marker ( approximately 45.9 cM). Abrg1 contributed approximately 35% of the genetic variance. The second locus, designated Abrg2, was mapped to chromosome 4 with an LOD score of 8.6 in 8-week-old male mice but an LOD score of only 2.0 in 8-week-old female mice at the D4Mit27 marker ( approximately 35 cM). Abrg2 contributed approximately 26% of the genetic variance. Epistasis between Abrg1 and Abrg2 was detected and accounted for approximately 12% of the genetic variance. The combination of these two QTL has major effects (>70%) on the regulation of plasma human apoB levels in the tested population. In summary, we have identified two novel loci that have a major role in the regulation of plasma apoB levels and are likely to regulate the secretory pathway of apoB. The human orthologs for the Abrg loci are strong candidates for human disorders characterized by altered plasma apoB levels, such as FCHL and familial hypobetalipoproteinemia.

Analysis of Variance↗