大肠癌P21,P53蛋白表达和k—ras基因,P53基因突变研究

用免疫组化技术和ＰＣＲ－ＳＳＣＰ技术对高、中、低分化大肠腺癌、癌旁粘膜、正常粘膜及大肠腺癌型息肉的Ｐ２１、Ｐ５３蛋白表达和ｋ－ｒａｓ基因、Ｐ５３基因突变进行检测。结果,大肠腺癌Ｐ２１、Ｐ５３蛋白表达比大肠腺瘤增多,但增加不显著（Ｐ〉０．０５）,二组均比癌旁粘膜和正常粘膜Ｐ２１、Ｐ５３蛋白表达阳性率高（Ｐ〈０．０１）,大肠腺癌ｋ－ｒａｓ基因和Ｐ５３基因突变率比大肠腺瘤、癌旁粘膜和正常粘膜组显著增加     

Association between glutathione S-transferases M1, T1 and P1 gene polymorphisms and prostate cancer in Koreans

Prostate cancer (PCa) is the most commonly diagnosed cancer in the developed world, and the incidence of this cancer is rising rapidly in many countries. Several polymorphic genes encoding enzymes involved carcinogenesis have been studied as potential risk factor of prostate cancer. Genetic polymorphisms in glutathione S-transferases M1 (GSTM1), T1 (GSTT1) and P1 (GSTP1) genes have been constantly reported to have a meaningful effect on prostate cancer risk. But other surveys of this relationship have yielded inconsistent results. To assess the possible contribution of the GSTM1, GSTT1, and GSTP1 gene polymorphisms in prostate cancer, we performed a population-based study of 139 prostate cancer patients and 115 healthy controls based on their genotype distributions of the genes. There were no differences in distributions of genotype frequencies of GSTM1 and GSTP1 polymorphisms between prostate cancer patients and controls (OR 1.60, 95 % CI 0.886–2.860 for GSTM1 and OR 1.38, 95 % CI 0.739–2.577 for GSTP1). In contrast, the distribution of GSTT1-null genotype is significantly different between the prostate cancer case and controls (OR 0.26, 95 % CI 0.128–0.518, p < 0.001). Meanwhile, GSTP1 I/V and V/V genotypes were significantly associated with prostate cancer where the PSA level was more than 10.0 (OR 2.73, 95 % CI 1.319–5.639, p = 0.006). Thus, our data imply that the GSTT1-null genotype may not be a risk factor but a protective factor of prostate cancer and GSTP1 Val allele is a risk factor for the prostate cancer where the PSA level was high, although functional studies with larger sample size are necessary to elucidate these findings.     

Cytochrome P4501A1, glutathione S-transferase M1 and T1 gene polymorphisms in chronic myeloid leukemia

Polymorphic variants of cytochrome P4501A1 (CYP1A1), glutathione-S-transferase M1 (GSTM1) and T1 (GSTT1) distribution was studied in patients with chronic myeloid leukemia (CML) and healthy individuals. It was shown that homozygotes for the GSTT1 gene deletion occur significantly more frequently in the CML patient group compared to the control group (13.17% versus 24.10% in CML patients, Chi2 = 4.40, p < 0.05; OR = 2.09; 95% CI = 1.10-3.99). In contrast, no significant difference was observed between the healthy individuals and CML patients in the frequency of polymorphic variants of GSTM1 and CYP1A1 genes (p > 0.05).     

The sphingosine-1-phosphate receptors S1P1, S1P2, and S1P3 function coordinately during embryonic angiogenesis

Sphingosine-1-phosphate (S1P) elicits diverse cellular responses through a family of G-protein-coupled receptors. We have shown previously that genetic disruption of the S1P(1) receptor, the most widely expressed of the family, results in embryonic lethality because of its key role within endothelial cells in regulating the coverage of blood vessels by vascular smooth muscle cells. To understand the physiologic functions of the two other widely expressed S1P receptors, we generated S1P(2) and S1P(3) null mice. Neither the S1P(2) null mice nor the S1P(3) null mice exhibited significant embryonic lethality or obvious phenotypic abnormalities. To unmask possible overlapping or collaborative functions between the S1P(1), S1P(2), and S1P(3) receptors, we examined embryos with multiple S1P receptor mutations. We found that S1P(1) S1P(2) double null and S1P(1) S1P(2) S1P(3) triple null embryos displayed a substantially more severe vascular phenotype than did embryos with only S1P(1) deleted. We also found partial embryonic lethality and vascular abnormalities in S1P(2) S1P(3) double null embryos. Our results indicate that the S1P(1), S1P(2) and S1P(3) receptors have redundant or cooperative functions for the development of a stable and mature vascular system during embryonic development.     

Sphingosine 1-phosphate (S1P) receptor subtypes S1P1 and S1P3, respectively, regulate lymphocyte recirculation and heart rate

Sphingosine 1-phosphate (S1P) influences heart rate, coronary artery caliber, endothelial integrity, and lymphocyte recirculation through five related high affinity G-protein-coupled receptors. Inhibition of lymphocyte recirculation by non-selective S1P receptor agonists produces clinical immunosuppression preventing transplant rejection but is associated with transient bradycardia. Understanding the contribution of individual receptors has been limited by the embryonic lethality of the S1P(1) knock-out and the unavailability of selective agonists or antagonists. A potent, S1P(1)-receptor selective agonist structurally unrelated to S1P was found to activate multiple signals triggered by S1P, including guanosine 5'-3-O-(thio)triphosphate binding, calcium flux, Akt and ERK1/2 phosphorylation, and stimulation of migration of S1P(1)- but not S1P(3)-expressing cells in vitro. The agonist also alters lymphocyte trafficking in vivo. Use of selective agonism together with deletant mice lacking S1P(3) receptor reveals that agonism of S1P(1) receptor alone is sufficient to control lymphocyte recirculation. Moreover, S1P(1) receptor agonist plasma levels are causally associated with induction and maintenance of lymphopenia. S1P(3), and not S1P(1), is directly implicated in sinus bradycardia. The sustained bradycardia induced by S1P receptor non-selective immunosuppressive agonists in wild-type mice is abolished in S1P(3)-/- mice, whereas S1P(1)-selective agonist does not produce bradycardia. Separation of receptor subtype usage for control of lymphocyte recirculation and heart rate may allow the identification of selective immunosuppressive S1P(1) receptor agonists with an enhanced therapeutic window. S1P(1)-selective agonists will be of broad utility in understanding cell functions in vitro, and vascular physiology in vivo, and the success of the chemical approach for S1P(1) suggests that selective tools for the resolution of function across this broad lipid receptor family are now possible.     

Chromosomal localization and structure of the human P1 protamine gene

The human P1 protamine gene and mRNA were amplified with the use of the polymerase chain reaction and cloned into PTZ19R. The sequences were determined which revealed the presence of an intron. Southern and Northern hybridization analyses showed that the gene was single copy and that the mRNA was approximately 450 bases long. The gene was mapped to chromosome 16 with the use of a somatic cell hybrid panel and localized to the 21 region of the q arm by in situ hybridization of the human P1 protamine probe to human metaphase chromosomes.     

P19-dependent and P19-independent reversion of F1-V gene silencing in tomato

As a part of a project to develop a plant-made plague vaccine, we expressed the Yersinia pestis F1-V antigen fusion protein in tomato. We discovered that in some of these plants the expression of the f1-v gene was undetectable in leaves and fruit by ELISA, even though they had multiple copies of f1-v according to Southern-blot analysis. A likely explanation of these results is the phenomenon of RNA silencing, a group of RNA-based processes that produces sequence-specific inhibition of gene expression and may result in transgene silencing in plants. Here we report the reversion of the f1-v gene silencing in transgenic tomato plants through two different mechanisms. In the P19-dependent Reversion or Type I, the viral suppressor of gene silencing, P19, induces the reversion of gene silencing. In the P19-independent Reversion or Type II, the f1-v gene expression is restored after the substantial loss of gene copies as a consequence of transgene segregation in the progeny. The transient and stable expression of the p19 gene driven by a constitutive promoter as well as an ethanol inducible promoter induced a P19-dependent reversion of f1-v gene silencing. In particular, the second generation plant 3D1.6 had the highest P19 protein levels and correlated with the highest F1-V protein accumulation, almost a three-fold increase of F1-V protein levels in fruit than that previously reported for the non-silenced F1-V elite tomato lines. These results confirm the potential exploitation of P19 to substantially increase the expression of value-added proteins in plants.     

P1-450 and P3-450 gene expression and maximum life span in mice

The effects of beta-naphthoflavone on the inducibility of hepatic P1-450 and P3-450 mRNA were investigated in male B10.RIII/Sn, C57BL/10Sn, C3H/HeSnJ, and A/WYSn mice. Previous work has shown that the maximum level of aryl hydrocarbon hydroxylase induction in these strains correlates with maximum life span. In this study we found that the maximum inducible levels of P1- and P3-450 RNA were significantly different among the strains, and these levels also correlate with life span. The differences were not due to strain-specific differences in the kinetics of P1- or P3-450 RNA induction. The differences were specific to expression of the P-450 genes, since the levels of hepatic alpha-actin and albumin RNA were not significantly different among the strains, and specific RNA levels were normalized to the level of total polyadenylated RNA. beta-Naphthoflavone was found to induce alpha-actin mRNA approximately 2-fold and to transiently repress albumin RNA about 50% in all mouse strains. Maximum P1- and P3-450 gene expression correlated directly with the 10th deciles of survival of the mouse strains. Longer-lived strains expressed higher combined levels of P1- and P3-450 RNAs. Maximum P1- and P3-450 gene expression also correlated generally with the reported aryl hydrocarbon hydroxylase receptor levels of each strain. It is unlikely that the hepatic P1- and P3-450 genes are ever maximally induced under the sheltered laboratory conditions used to determine maximum life span, as we consistently find very low levels of P-450 expression in uninduced animals. These uninduced levels were not statistically different between the strains. Therefore, the reason for the relationship between maximum life span and maximum P1- and P3-450 inducibility is unclear at present.     

Human serum amyloid P component. cDNA isolation, complete sequence of pre-serum amyloid P component, and localization of the gene to chromosome 1

Complementary DNA clones corresponding to the human serum amyloid P component (SAP) were isolated, and the complete nucleotide and derived amino acid sequence of preSAP was determined. PreSAP biosynthesis is directed by a 1.1-kilobase mRNA. Synthesis and postsynthetic processing of preSAP in Xenopus oocytes result in secretion of a protein with mobility similar to native purified SAP when analyzed by sodium dodecyl sulfate gel electrophoresis. The human SAP gene is on chromosome 1, probably closely linked to the gene for C-reactive protein which encodes the related acute phase reactant found in human plasma.     

Isolation, characterization, and inactivation of the APA1 gene encoding yeast diadenosine 5'',5''''''-P1,P4-tetraphosphate phosphorylase.

The gene encoding diadenosine 5',5'-P1,P4-tetraphosphate (Ap4A) phosphorylase from yeast was isolated from a lambda gt11 library. The DNA sequence of the coding region was determined, and more than 90% of the deduced amino acid sequence was confirmed by peptide sequencing. The Ap4A phosphorylase gene (APA1) is unique in the yeast genome. Disruption experiments with this gene, first, supported the conclusion that, in vivo, Ap4A phosphorylase catabolizes the Ap4N nucleotides (where N is A, C, G, or U) and second, revealed the occurrence of a second Ap4A phosphorylase activity in yeast cells. Finally, evidence is provided that the APA1 gene product is responsible for most of the ADP sulfurylase activity in yeast extracts.     

Mutator and antimutator effects of the bacteriophage P1 hot gene product

The Hot (homolog of theta) protein of bacteriophage P1 can substitute for the Escherichia coli DNA polymerase III theta subunit, as evidenced by its stabilizing effect on certain dnaQ mutants that carry an unstable polymerase III epsilon proofreading subunit (antimutator effect). Here, we show that Hot can also cause an increase in the mutability of various E. coli strains (mutator effect). The hot mutator effect differs from the one caused by the lack of theta. Experiments using chimeric theta/Hot proteins containing various domains of Hot and theta along with a series of point mutants show that both N- and C-terminal parts of each protein are important for stabilizing the epsilon subunit. In contrast, the N-terminal part of Hot appears uniquely responsible for its mutator activity.