Yu-Rong Xia

Localization of the gene for the DNA-binding protein AP-2 to human chromosome 6p22.3-pter.

A variety of cellular proteins bind to cellular and viral enhancer elements. One such factor, known as AP-2, is a 52-kDa transcription factor identified by its interaction with the SV40 and metallothionein enhancers. In addition, it has been found that AP-2 binds to the SV40 T-antigen. AP-2 activity is mediated by both the state of cellular differentiation and changes in signal transduction pathways, suggesting a potential role of AP-2 in the regulation of diverse cellular processes. As part of an effort to examine the chromosomal organization of cellular genes encoding transcription factors, we report the mapping of the gene encoding AP-2 to human chromosome 6p22.3-24 by analysis of somatic cell hybrids and in situ hybridization to chromosomes.

A cluster of stearoyl CoA desaturase genes, Scd1 and Scd2, on mouse Chromosome 19

Species: Mouse Locus name: Stearoyl CoA desaturase 1, Stearoyl CoA desaturase 2 Locus symbols: Scdl, Scd2 Map position: Scdl and Scd2 are located on Chromosome (Chr) 19: centromere-D19Ucla5-(4.8 ± 2.7)-D19Ucla1-(6.4 ± 3.1)Scdl, Scd2-(4.8 ± 2.7)-D19Mit4 (Fig. 1). Method of mapping: Restriction fragment length variants were identified, following digestion of genomic DNA and hybridization with Scdl and Scd2 cDNA probes. Southern blot analysis was performed on a panel of 67 samples from a [C57BL/6J X Mus spretus) F, x C57BL/6J] backcross [1]. As judged by Southern analysis, the Scdl and Scd2 probes exhibited no crosshybridization under the conditions employed. A Pvull variant was detected with a 32P-labeled Scdl probe following a final wash at 60°C, in 1.0 x SSC/0.1% SDS. C57BL/6J DNA exhibited a single band of 2.7 kb, Mus spretus DNA a single 2.1-kb band, and F t DNA exhibited both bands. An EcoRl variant was detected with an Scd2 probe labeled by fluorescein-11-dUTP and Klenow polymerase (Amersham, Gene Images random prime labeling module). Following a final wash at 60°C, in 0.1x SSC/0.1% SDS, hybridizing bands were detected by incubation of the blot with anti-fluorescein alkaline phosphatase conjugate (Amersham, Gene Images CDP-Star detection module). DNA from C57BL/6J mice exhibited a single band of 3.0 kb, DNA from Mus spretus a single band of 6.6 kb, and DNA from F, hybrids exhibited both bands. The backcross mice were then scored for the presence or absence of the Mus spretus bands generated by both probes. These backcross mice have been typed for more than 400 markers spanning the genome. Linkage was detected with Map Manager v.2.6.5.

Paraoxonase-2 Modulates Stress Response of Endothelial Cells to Oxidized Phospholipids and a Bacterial Quorum–Sensing Molecule

Objective—Chronic infection has long been postulated as a stimulus for atherogenesis. Pseudomonas aeruginosa infection has been associated with increased atherosclerosis in rats, and these bacteria produce a quorum-sensing molecule 3-oxo-dodecynoyl-homoserine lactone (3OC12-HSL) that is critical for colonization and virulence. Paraoxonase 2 (PON2) hydrolyzes 3OC12-HSL and also protects against the effects of oxidized phospholipids thought to contribute to atherosclerosis. We now report the response of human aortic endothelial cells (HAECs) to 3OC12-HSL and oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (Ox-PAPC) in relation to PON2 expression. Methods and Results—Using expression profiling and network modeling, we identified the unfolded protein response (UPR), cell cycle genes, and the mitogen-activated protein kinase signaling pathway to be heavily involved in the HAEC response to 3OC12-HSL. The network also showed striking similarities to a network created based on HAEC response to Ox-PAPC, a major component of minimally modified low-density lipoprotein. HAECs in which PON2 was silenced by small interfering RNA showed increased proinflammatory response and UPR when treated with 3OC12-HSL or Ox-PAPC. Conclusion—3OC12-HSL and Ox-PAPC influence similar inflammatory and UPR pathways. Quorum sensing molecules, such as 3OC12-HSL, contribute to the proatherogenic effects of chronic infection. The antiatherogenic effects of PON2 include destruction of quorum sensing molecules.

Mapping of the gene for the cardiac sarcolemmal Na+Ca2+ exchanger to human chromosome 2p21–p23

The cardiac sarcolemmal Na(+)-Ca2+ exchanger is the primary mechanism for extrusion of calcium from the cardiac myocyte and therefore is important in regulating cardiac contractility. As part of an effort to determine whether the exchanger is associated with any genetic disorders of the heart or blood pressure, we have assigned the exchanger gene (designated NCX1) to human chromosome 2p21-p23 by analysis of a panel of mouse-human somatic cell hybrids and by in situ hybridization.

Temporal and Tissue-Specific Patterns of Pon3 Expression in Mouse: In situ Hybridization Analysis

PON3 is a member of the paraoxonase gene family that includes PON1 and PON2. For example, PON3 and PON1 share approximately 60% identity at the amino acid level. Recent studies have demonstrated that PON3 is present in human and rabbit HDL but not in mouse HDL. Mouse PON3 appears to be cell-associated and is expressed in a wide range of tissues such as liver, adipose, macrophage, and the artery wall. In vitro studies have shown that PON3 can prevent LDL oxidation and destroy bacterial quorum-sensing molecules. Previous studies also showed that human PON3 transgenic mice were protected from obesity and atherosclerosis in both the C57BL/6 J wild-type and LDLR knockout genetic background. Administration of adenovirus expressing the human PON3 gene into apoE -/- mice also decreased atherosclerotic lesion formation. In order to further understand the functions of PON3 in physiology and disease, we performed in situ hybridization analysis to examine Pon3 gene expression patterns in newborn and adult mice, in various tissues, including atherosclerotic lesions of apoE -/- mice. Our results show relatively high levels of Pon3 mRNA labeling in the adrenal gland, submaxillary gland, lung, liver, adipose, pancreas, large intestine, and other tissues of newborn mice. In the adult mouse, Pon3 mRNA levels were much lower in the corresponding tissues as mentioned above for the newborn mouse. Sections of the aortic root from the hearts of both wild-type and apoE -/- mice displayed moderate levels of Pon3 mRNA labeling. Pon3 mRNA was also detected in the atherosclerotic lesion areas at the aortic root of apoE -/- hearts. Our data revealed that mouse Pon3 is expressed in a wide range of tissues, and that its expression is temporally controlled.

Srbl maps to mouse Chromosome 5 in a region harboring putative QTLs for plasma lipoprotein levels

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Assignment of the human pancreatic colipase gene to chromosome 6p21.1 to pter

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A locus on the X Chromosome is linked to body length in mice

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The L-isoaspartyl/D-aspartyl protein methyltransferase gene (PCMT1) maps to human chromosome 6q22.3-6q24 and the syntenic region of mouse chromosome 10.

Pancreatic colipase is a 12-kDa polypeptide cofactor for pancreatic lipase (EC 3.1.1.3), an enzyme essential for the absorption of dietary long-chain triglyceride fatty acids. Colipase is thought to anchor lipase noncovalently to the surface of lipid micelles, counteracting the destabilizing influence of intestinal bile salts. Using primers derived from the known amino acid sequence, we have used the polymerase chain reaction to produce a cDNA clone corresponding to the complete coding region of the human procolipase mRNA. Southern blot analysis of genomic DNA from a panel of mouse-human somatic cell hybrids indicated that the colipase gene (CLPS) resides on human chromosome 6. Further analysis of somatic cell hybrids carrying chromosome 6 translocations permitted regional localization of CLPS to the 6p21.1-pter region.

Assignment of the mouse ataxia-telangiectasia gene (Atm) to mouse Chromosome 9

Linkage between body length (anus to nose (AN) length) and three markers on the mouse X Chromosome was found in an interspecific backcross ((C57BL/6J x Mus spretus) Fl x C57BL/6J), designated BSB. A cross of 409 mice were scored for 148 genetic markers distributed on all chromosomes except the Y Chromosome. Statistical analysis revealed highly significant linkage (LOD score 5.5) between body length and a locus in the middle portion of the X Chromosome, the nearest markers being the microsatellite marker DXMit73 and a farnesyl pyrophosphate locus (Fpsl9) 3.1 cM proximal to DXMit73. The locus explains 10% of the variance in AN length and affects both males and females to about the same extent.