Molecular evolutionary analysis of the high-affinity K+ transporter gene family in angiosperms.

The high-affinity K(+) transporter (HKT) family comprises a group of multifunctional cation transporters widely distributed in organisms ranging from Bacteria to Eukarya. In angiosperms, the HKT family consists primarily of nine types, whose evolutionary relationships are not fully understood. The available sequences from 31 plant species were used to perform a comprehensive evolutionary analysis, including an examination of selection pressure and estimating phylogenetic tree and gene duplication events. Our results show that a gene duplication in the HKT1;5/HKT1;4 cluster might have led to the divergence of the HKT1;5 and HKT1;4 subfamilies. Additionally, maximum likelihood analysis revealed that the HKT family has undergone a strong purifying selection. An analysis of the amino acids provided strong statistical evidence for a functional divergence between subfamilies 1 and 2. Our study was the first to provide evidence of this functional divergence between these two subfamilies. Analysis of co-evolution in HKT identified 25 co-evolved groups. These findings expanded our understanding of the evolutionary mechanisms driving functional diversification of HKT proteins.

Molecular analysis of MLH1 variants in Chinese sporadic colorectal cancer patients.

Single nucleotide polymorphisms (SNPs) in mismatch repair genes, especially in the MLH1 gene, are closely associated with susceptibility to hereditary nonpolyposis colorectal cancer. However, few relevant findings are available regarding the association between sporadic colorectal cancer (SCRC) and SNPs of MLH1 in Chinese patients. Therefore, the present study aimed to describe the pathogenic association between three important MLH1 polymorphisms and SCRC in the Chinese population. Peripheral blood samples from 156 SCRC patients and 311 healthy controls were collected. DNA was purified from peripheral blood, and the V384D, R217C, and I219V polymorphisms were evaluated using high-resolution melting analysis and direct sequencing. The association between the three important MLH1 polymorphisms and clinical pathological features of the SCRC patients was analyzed. In addition, PMS2-MLH1 protein interactions were determined by co-immunoprecipitation (Co-IP) to determine the protein functional alteration induced by these SNPs. Among the three polymorphisms, V384D was significantly associated with the risk of SCRC (OR = 31.36, P < 0.0001). The allele frequencies were 4.81 and 0.16% in the SCRC group. No association was found between SCRC and R217C, or between SCRC and I219V. Moreover, the allele frequency of R217C was significantly higher in the SCRC patients younger than 60 years than in those older than 60 years. Co-IP showed that the MLH1 R217C, V384D, and I219V variants had relative binding abilities with PMS2 of 0.59, 0.70, and 0.80, respectively, compared with the wild-type. These findings suggest that MLH1 V384D could be a promising genetic marker for susceptibility to SCRC.

Molecular cloning and expression analysis of MAT1 gene in black tiger shrimp (Penaeus monodon).

MAT1 (ménage à trois 1), an assembly factor and targeting subunit of the CDK-dependent kinase (CAK), can regulate the cell cycle, transcription, and DNA repair. This study was intended to investigate the role of MAT1 in the reproductive maturation of black tiger shrimp (Penaeus monodon). In this study, the P. monodon MAT1 (PmMAT1) gene was identified and characterized. The full-length cDNA of PmMAT1 was 1490 bp in length with an open-reading frame of 993 bp corresponding to 330 amino acids. The temporal expression of PmMAT1 in various tissues was measured by quantitative real-time PCR with the highest expression observed in ovaries. In the ovaries, the PmMAT1 gene was continuously but differentially expressed during the maturation stages. Comparative analyses of MAT1, CDK7, and cyclin H in the CAK complex of P. monodon indicated that the expression of CDK7 and cyclin H coincided with that of MAT1 during the ovary maturation stages. Serotonin (5-HT) injection promoted the expression level of PmMAT1 in the ovaries of shrimp at 6-48 h post-injection. These results indicate that PmMat1 plays a prominent role in the process of ovarian maturation.

MicroRNA-26b inhibits osteosarcoma cell migration and invasion by down-regulating PFKFB3 expression.

MicroRNAs regulate target gene expression and are involved in cell proliferation, apoptosis, differentiation, tumor invasion, and cancer stem cell regulation, among other processes. MicroRNA-26b (miR-26b) is closely related to tumor occurrence and development. In this study, we analyzed miR-26b expression in osteosarcoma tissue, its effect on Saos-2 osteosarcoma cell proliferation and invasion, and its relationship with 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) expression. Osteosarcoma tissue was obtained from surgical patients and normal tissue adjacent to the tumor was used as a control. Real-time polymerase chain reaction was applied to detect miR-26b expression in cancer tissue and normal tissue. A vector expressing miR-26b was constructed and transfected into Saos-2. An MTT assay, cell invasion assay, and scratch experiment were used to analyze the effect of miR-26b on Saos-2 cell proliferation, invasion, and migration abilities. Western blotting analysis was performed to investigate the role of miR-26b on PFKFB3 expression. miR-26b expression in normal tissue was 7.55-fold higher than in osteosarcoma tissue (t = 10.20, P = 0.006). Compared with control tissue, miR-26b significantly inhibited osteosarcoma proliferation, migration, and invasion (P < 0.05). Western blotting results revealed that PFKFB3 protein expression decreased in Saos-2 cells after transfection with miR-26b. miR-26b was down-regulated in osteosarcoma tissue. miR- 26b may inhibit osteosarcoma cell proliferation, migration, and invasion by regulating PFKFB3 protein expression. miR-26b may have a tumor suppressor role in tumor occurrence and development.

Characterization and expression analysis of a cyclin B gene from black tiger shrimp (Penaeus monodon).

The open reading frame of black tiger shrimp (Penaeus monodon) cyclin B (Pmcyclin B) was identified, based on cDNA sequence registered in GenBank (accession No. EF015590). The target sequence was 1206 bp, corresponding to 401 amino acids. Two conserved signature sequences of the cyclin B gene family were found in the Pmcyclin B deduced aa sequence. Temporal expression of Pmcyclin B in different tissues, including ovary, lymphoid organ, brain, blood, muscle, heart, gill, hepatopancreas, and intestine, were quantified by quantitative real time PCR. Messenger RNA expression levels of Pmcyclin B were greatest in the ovary, compared to other tissues (P < 0.05). Temporal expression of Pmcyclin B in the ovary at six different developmental stages was investigated by real-time PCR; no significant difference was observed (P < 0.05). Recombinant Pmcyclin B protein and its polyclonal antibody were successfully produced. Western blot analysis revealed differential expression of Pmcyclin B in ovaries in developmental stages II to IV; a positive signal (45 kDa) was observed in all ovarian stages assessed, but was most intense at stage III. Pmcyclin B protein was assessed by immunohistochemistry and was localized to the cytoplasm of prophase oocytes at stage II and enriched in the nuclei of pro-metaphase oocytes at stages III and IV. Results from this study indicate that Pmcyclin B is constitutively expressed and plays an important role in ovarian maturation in P. monodon.

Association between five common polymorphisms in microRNA genes and the risk of gastric cancer: a meta-analysis.

Gastric cancer (GC) is a prevalent disease with a high mortality rate, especially in developing countries. Accumulating evidence suggests that single nucleotide polymorphisms in microRNA (miRNA) genes might influence the susceptibility to GC; such sequence variation might contribute to the development of disease by altering crucial cellular pathways. In this study, we assessed the correlation between the miR-146a G>C, miR-196a-2 C>T, miR-499 T>C, miRNA-27a A>G, and miRNA-149 T>C polymorphisms and the susceptibility to GC. A comprehensive literature search for relevant studies published prior to August 2014 was conducted using PubMed/Medline, Embase, Web of Science, the Cochrane Library, and CNKI databases along with Google Scholar. Meta-analysis was performed using odds ratios (ORs) and 95% confidence intervals (CIs) as effect measures, incorporating 19 studies encompassing 8285 patients and 10,716 controls. Allelic, dominant, recessive, homozygous, and heterozygous genetic models were examined. Pooled results showed that none of the five polymorphisms studied were statistically related to GC. Stratified analyses by ethnicity and source of controls were conducted for miR- 146a G>C and miR-196a-2 C>T. Subgroup analysis suggested that the miR-146a G allele might increase the risk of GC in hospital-based case-control (HCC) but not in population-based case-control studies (HCC: recessive model: OR = 1.23, 95%CI = 1.10-1.37, P < 0.001; heterozygous model: OR = 1.19, 95%CI = 1.06-1.34, P = 0.004). Overall, this meta-analysis failed to detect an association between five common miR-146a gene polymorphisms and GC susceptibility. However, this does not necessarily completely rule out a correlation between miRNA polymorphisms and GC susceptibility.

Expression of EpCAM and Wnt/ ß-catenin in human colon cancer.

The aims of this study were to explore the correlation between the expression of EpCAM and the Wnt/ß-catenin pathway in human colon cancer and its clinical significance for the evaluation of cancer prognosis. Samples from colon cancer, para-carcinoma, or benign intestinal tissue from individual patients (50) and from normal intestinal mucosal tissues (20) were obtained from the Pathology Department of the Shandong Province Binzhou People's Hospital (Shandong, China). Immunohistochemistry was used to detect the expression levels of EpCAM and ß-catenin proteins in these tissues, and the prognoses of the patients from whom the samples were derived were determined on follow-up examination. The corresponding in vitro mechanistic siRNA experiments were subsequently performed in the human colon cancer cell line HCT116 to observe the regulatory effects of silencing EpCAM expression on the Wnt/ß-catenin pathway. From these analyses, we determined that the expression levels of EpCAM and ß-catenin were higher in cancer tissues compared with other tissues from the same patient, and that the expression of EpCAM and Wnt/ß- catenin in colon cancers were positively correlated. The prognostic analysis showed an inverse correlation between EpCAM and Wnt/ß- catenin expression and patient prognosis. A further examination of cellular mechanisms confirmed that the silencing of EpCAM led to decreased expression of Wnt/ß-catenin, and thus reduced proliferation and increased the apoptosis ratio in the cells. These results suggest that suppression of EpCAM might be a new approach for treating colon cancer.

Detection of a mutation at codon 43 of the rpsL gene in Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae by PCR-RFLP.

The aim of this study was to develop a method to detect a point mutation in the ribosomal S12 protein (rpsL) gene in streptomycin-resistant strains of Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was developed to detect a point mutation in codon 43 of the rpsL gene in X. oryzae pv. oryzicola and X. oryzae pv. oryzae. The 304-bp PCR product from the rpsL gene was digested by MboII to form two fragments (201 and 103 bp) if there was a mutation at codon 43, or three fragments (146, 103, and 55 bp) if there was no mutation. Compared with the results from nucleotide sequencing, the PCR-RFLP method was accurate in detecting the point mutation at codon 43 of the rpsL gene in streptomycin-resistant strains of X. oryzae pv. oryzicola and X. oryzae pv. oryzae. These results indicate that the PCR-RFLP is a simple, rapid and reliable method for detecting the point mutation at codon 43 of the rpsL gene.

Correlation between DQB1 genetic polymorphism and genetic susceptibility in patients diagnosed with irritable bowel syndrome with diarrhea.

We examined patients of Han nationality diagnosed with irritable bowel syndrome with diarrhea (IBS-D) in Guangdong, China, to analyze the correlation between DQB1 allele polymorphisms and the genetic susceptibility to IBS-D. A total of 120 IBS-D patients of Han nationality in Guangdong, China, and 60 healthy control volunteers were included. DQB1 allele polymorphisms were investigated by polymerase chain reaction. Subjects' serum interleukin (IL)-10 level, colonic permeability, and tight junction marker zonula occludens 1 (ZO1) mRNA level were also investigated. Our data showed that the DQB1*02 allele frequency was significantly higher in IBS-D patients, while the DQB1*0603 frequency was lower than in healthy volunteers. The DQB1*03, DQB1*04, DQB1*05, DQB1*0601, DQB1*0602, and DQB1*0604 alleles did not show significant differences between IBS-D patients and healthy controls. Furthermore, patients with DQB1*03- positive and DQB1*0603-negative alleles showed more severe colonic permeability and lower serum IL-10 level and ZO1 level compared to healthy controls or even IBS-D patients with other genotypes. The present study indicated the DQB1*02 or DQB1*0603 alleles are related to IBS-D occurrence in Guangdong, China, and the mechanism of the disease may be related to reduced serum IL-10 levels.

Characterization and kinetics of MHC class I-restricted presentation of a soluble antigen delivered by liposomes.

We describe in this report the characterization and kinetics of MHC class I-restricted presentation of a soluble antigen delivered by liposomes. pH-sensitive liposomes delivered ovalbumin (OVA) to the class I pathway more efficiently than pH-insensitive liposomes; the latter showed competence in the class I-restricted sensitization only when a large antigen loading dose was used. Such sensitization of EL4 cells resulted from substantial delivery of the ingested liposomal OVA to the cytosolic compartment as revealed with immunogold electron microscopy. Most of the ingested liposomal OVA were rapidly catabolized and released into the extracellular medium. The residual processed antigen took about 2 h to egress to the cell surface for recognition by CTL. The liposome-mediated antigen presentation exhibited a transient kinetics which was manipulable with antigen dose. Brefeldin A, an ER-to-Golgi transport inhibitor, strongly inhibited such presentation. The antigens displayed on the cell surface could also be removed by a brief acid wash of the cells and subsequently reappeared on the surface if an intracellular pool of antigen existed at the time of acid wash.