Fig 1 - uploaded by Peter Weyrich
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Structure of the Par6 α gene. The gene encoding Par6 α is located on chromosome 16q22 and comprises three exons ( Ex1 – Ex3 , white boxes ). The outer nucleotide numbers ( − 2117 and 1821) indicate the genomic region analysed for this work. The GenScan algo-
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Partitioning-defective protein-6alpha (Par6alpha) has recently been demonstrated to negatively regulate insulin signalling in murine myoblasts. To address whether Par6alpha plays a role in human physiology, the present study investigated whether mutations exist in the Par6alpha gene and whether these mutations, if present, are associated with pre-d...
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... Oligonucleotide prim- ers were designed in order to amplify the gene encoding Par6α. Use of these primers revealed amplification prod- ucts of approximately 400 bp. By 14 overlapping reac- tions, the complete gene (part of the promoter [2.1 kb], all exons/introns and the 3′ untranslated region) was ampli- fied by PCR in a screen of 50 subjects (Fig. 1). The PCR products were then sequenced bidirectionally using an ABI Prism dye terminator cycle sequencing ready reaction Table 1 Characteristics of the subjects divided according to geno- type of the −336A/G polymorphism in the Par6α gene kit (Applied Biosystems, Foster City, CA, USA) and an ABI Prism 310 automated sequencer (Applied ...
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... last accessed in January 2005), were not detected in our popu- lation. However, a novel SNP (A/G) was detected 336-bp upstream of the translational start codon. Interestingly, using the GenScan software [18], we found that the SNP was located within a 40-bp region (−340 to −300) predicted to function as a promoter for the Par6α gene (Fig. 1). The allelic frequency of this rare SNP was 0.03 in our popu- lation. Genotype frequencies were in Hardy-Weinberg equilibrium (p=0.34 according to the Chi square test). For statistical analysis, the results for subjects homozygous (n=2) and heterozygous (n=41) for the −336G allele were combined (R/G, n=43) and compared with those of ...
Citations
... A potential regulator of aPKC in insulin signalling is partitioning-defective protein 6α (Par6α), a scaffold protein that interacts with the regulatory domain of aPKC. We A c c e p t e d M a n u s c r i p t 4 previously identified a single nucleotide polymorphism in the human Par6α promoter that was coupled with lower Par6α expression and better insulin sensitivity (Weyrich et al., 2005). Overexpression of human Par6α in C2C12 murine myoblasts increased aPKC activity and resulted in repression of insulin-induced glycogen synthesis by enhancing the negative aPKC – IRS1 – PI3K feedback loop (Weyrich et al., 2004). ...
... In C2C12 cells, the use of the ∆PB1-Par6α mutant clearly indicates that the Par6α/aPKC complex acts negatively on Akt1 and insulin-induced glycogen synthesis, and that the major contribution to this inhibition comes directly from aPKC. A c c e p t e d M a n u s c r i p t 15 polymorphism in the human Par6α promoter leads to reduced Par6α expression and is associated with increased insulin sensitivity in humans (Weyrich et al., 2005), this mechanism could contribute to the development of insulin resistance in the in-vivo situation for individuals with a higher expression of Par6α. with identical binding affinity to wild-type and ∆PB1-Par6α. ...
A single nucleotide polymorphism in the partitioning defective protein-6alpha (Par6alpha) promoter is coupled with lower Par6alpha expression and better insulin sensitivity, whereas overexpression of Par6alpha in C2C12 myoblasts inhibits insulin-induced protein kinase B/Akt1 activation and glycogen synthesis. Here we show that a direct interaction of Par6alpha with atypical protein kinase C (aPKC) is crucial for this inhibition. A DeltaPB1-Par6alpha deletion mutant that does not interact with aPKC neither increased aPKC activity nor interfered with insulin-induced Akt1 activation in C2C12 cells. Further, T34 phosphorylation of Akt1 through aPKC is important for inhibition of Akt1. When Par6alpha was overexpressed, activation of wild-type Akt1 (-59.3%; p=0.049), but not T34A-Akt1 (+2.9%, p=0.41) was reduced after insulin stimulation. The resistance of T34A-Akt1 to Par6alpha/aPKC-mediated inhibition was also reflected by reconstitution of insulin-induced glycogen synthesis. In summary, Par6alpha-mediated inhibition of insulin-dependent glycogen synthesis in C2C12 cells depends on the direct interaction of Par6alpha with aPKC and on aPKC-mediated T34 phosphorylation of Akt1.
This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.
Tristetraprolin (TTP) is an intracellular protein that modulates the production of cytokines, including TNFalpha, by binding to and destabilizing the mRNAs of these cytokines. Therefore, differences in TTP gene expression may affect the severity of inflammatory diseases, such as rheumatoid arthritis (RA). We searched for polymorphisms in the human TTP gene and for this purpose, we sequenced the entire TTP gene in 20 Japanese individuals (ten with RA and ten healthy volunteers) and found one single nucleotide polymorphism (SNP) in the promoter region. We analyzed this SNP (A/G) by restriction fragment length polymorphism method in 155 RA patients and 100 control subjects. While the frequency of A allele in this SNP was similar in RA patients (74.5%) and controls (76.0%), the disease duration in RA patients with genotype GG was shorter than that of patients with genotypes AA/AG and RA patients with genotype GG had a higher probability of being treated with infliximab. We studied the difference in promoter activity between the two alleles by luciferase assay and found that the promoter activity of TTP promoter region with allele A was around two-fold higher than that with allele G. We conclude that this SNP in the promoter region of the TTP gene mildly affects promoter activity, and thus, may influence the disease activity of inflammatory disorders including RA.
