Cell adhesion receptors and cancer

Cell-to-cell and cell-to-extracellular matrix (ECM) interactions in the functions of cell adhesion and signal transduction are important in global control of cell phenotypes and cell behavior and are crucial for maintenance of homeostasis and structural/functional stabilization of tissues and organs. Cell adhesion receptors are recognized as the molecular basis of cell adhesion. Cadherin and Integrin are widely expressed adhesion receptors in most tissues. They are transmembrane glycoproteins which, through their cytoplasmic domain, bind to many proteins at the inner surface of cell membrane to form molecule-linkage complexes and then connect with the cytoskeleton. Through cell adhesion receptors a network functioning as cell adhesion and signal transduction is organized between tissue cells and cell-ECM. In this regard cell adhesion receptors play an important role in regulation of morphogenesis, cell-cell recognition, cell migration, cell sorting and the determination of cell's fate in development. They mediate cell functions and their fault expression is intimately correlated with development of disorders like cancer. Several isoforms of Integrin were found to have tumor suppressor effect. Some components in the molecule-linkage of focal contact are actin-binding proteins as well as substrates of kinase in the Integrin initiated signal pathway to play a role as signal transducer. Some of these molecules exhibited tumor suppressor effect too. Decreased expression of E-Cadherin has been demonstrated in many epithelium originated carcinomas. Cadherin associated membrane adhesion plaque molecule β-Catenin is also involved in the oncogene Wnt signal pathway. Both E-Cadherin and β-Catenin were proved respectively with tumor suppressor effect against invasiveness and metastasis. That Cadherin is important for the posttranslationally functional expression of Connexin has been supported by evidence from developmental biology and cancer cell differentiation studies to suggest that some sort of interrelation feedback control exists between the two signal pathways.     

Suitable internal control genes for qRT-PCR normalization in cotton fiber development and somatic embryogenesis

The mechanisms of cotton fiber development and somatic embryogenesis have been explored sys-tematically with microarray and suppression subtractive hybridization. Real-time RT-PCR provides the simultaneous measurement of gene expression in many different samples,with which the data from microarray or others can be confirmed in detail. To achieve accurate and reliable gene expression re-sults,normalization of real-time PCR data against one or several internal control genes is required,which should not fluctuate in different tissues during various stages of development. We assessed the gene expression of 7 frequently used housekeeping genes,including 18S rRNA,Histone3,UBQ7,Actin,Cyclophilin,Gbpolyubiquitin-1 and Gbpolyubiquitin-2,in a diverse set of 21 cotton samples. For fiber developmental series the expression of all housekeeping genes had the same down tendency after 17 DPA. But the expression of the AGP gene(arabinogalactan protein) that has high expression level at the later fiber development stage was up-regulated from 15 to 27 DPA. So the relative absolute quanti-fication should be an efficient and convenient method for the fiber developmental series. The expres-sion of nonfiber tissues series varied not so much against the fiber developmental series. And three best control genes Histone3,UBQ7 and Gbpolyubiquitin-1 have to be used in a combinated way to get better normalization.     

Two different gene loci related to the spatial patterning of brain ventricle in vertebrate

Observations on living embryonic brains and the microstructure of brain ventricle of goldfish revealed that there are two brain ventricle phenotypes in gynogenetic haploid embryos. One phenotype is as normal as that of the control inbreeding diploid embryos, which has normal differentiated forebrain, midbrain and hindbrain. Another phenotype is obviously abnormal, the brain patterning is irregular, and no distinct brain ventricle can be observed. The ratio of haploid embryos with normal brain pattern to that with abnormal brain pattern is 1∶3. This ratio indicates that there are two gene loci involved in the spatial patterning of the brain ventricle. Since the possibility that deleterious recessive mutant alleles exist on both of the two gene loci had been excluded in this experiment, the phenotype represented the expressional state rather than the genotype of these two genes. Therefore, the ratio of 1∶3 suggests that the expressing probability for each copy of the two genes is 50%, and the regulatory mechanism of the expression is based on two sets of chromosomes, controlled by the rule of the diploid-dependent regulatory mechanism.     

Two different gene loci related to the spatial patterning of brain ventricle in vertebrate

Observations on living embryonic brains and the microstructure of brain ventricle of goldfish revealed that there are two brain ventricle phenotypes in gynogenetic haploid embryos. One phenotype is as normal as that of the control inbreeding diploid embryos, which has normal differentiated forebrain, midbrain and hindbrain. Another phenotype is obviously abnormal, the brain patterning is irregular, and no distinct brain ventricle can be observed. The ratio of haploid embryos with normal brain pattern to that with abnormal brain pattern is 1:3. This ratio indicates that there are two gene loci involved in the spatial patterning of the brain ventricle. Since the possibility that deleterious recessive mutant alleles exist on both of the two gene loci had been excluded in this experiment, the phenotype represented the expressional state rather than the genotype of these two genes. Therefore, the ratio of 1:3 suggests that the expressing probability for each copy of the two genes is 50%, and the regulatory mechanism of the expression is based on two sets of chromosomes, controlled by the rule of the diploid-dependent regulatory mechanism.     

Derivation of androgenetic embryonic stem cells from m-carboxycinnamic acid bishydroxamide (CBHA) treated androgenetic embryos

The androgenetic embyronic stem (aES) cells are useful models in studying the effects of imprinted genes on pluripotency maintaining and embryo development. The expression patterns of imprinted genes are significantly different between uniparental derived aES cells and zygote-derived embryonic stem (ES) cells, therefore, the imprinting related cell pluripotency needs further exploitation. Several approaches have been applied in generation of androgenetic embryos and derivation of aES cell lines. Here, we describe a method to generate androgenetic embryos by injecting two mature sperms into one enucleated oocyte. Then these androgenetic embryos were treated with a histone deacetylase inhibitor: m-carboxycinnamic acid bishydroxamide (CBHA). Further, aES cell lines were successfully derived from these treated androgenetic embryos at blastocyst stage. The CBHA could improve not only the quality of androgenetic embryos, but also the efficiencies of aES (CaES) cells derivation and chimeric mice generation. The imprinted gene expression pattern in the CBHA treated embryo-derived aES (CaES) cells was also highly similar to that of zygote-derived ES cells.     

Establishment ofChlamydomonas reinhardtii chloroplast expression

An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Southern-blotting, Northern-blotting and Western-blotting assays after selecting on resistant medium and incubating in the dark. The results show that the chimeric gene has replaced the chIL gene of C. reinhardtii chloroplast genome and expressed correctly under the control of the C. reinhardtii chloroplast double promoters 5' chlL-5' atpA. The analysis of SDS-PAGE indicates that the expressed protein accounts for 5.31 % of total soluble protein.     

Characterization of a calmodulin binding protein kinase from<Emphasis Type="Italic">Arabidopsis thalian</Emphasis>

A full-length calmodulin binding protein kinase cDNA ,AtCBK1 ,from Arabidopsis has been isolated by screening of an Arabidopsis cDNA library and by 5′-RACE-Northern blot and in situ hybridization indicated that the expression of AtCBK1 was more abundant in the vascular bundles and the meristems than in other tissues,The phylogenetic analyses revenl that AtCBK1 is different from animal CaMKs and it falls into CRK subgroup,indicating that they may come from different ancestors,The result suggests that AtCBK1 encoldes a CaM-binding serine/threonine protein kinase.     

Effect of HS2 and HS3 elements on erythroid-specific expression in transgenic mice

The expression plasmids CMV/GFP, HS2ALL, HS3ALL and HS23ALL were selected to investigate the effect of HS2 and HS3 element on erythroid-specific expression in transgenic mice. These plasmids were digested with restriction enzymes and purified. And five DNA fragments, CMV/GFP, HS2/GFP, CMV/HS2/GFP, HS23/GFP and HS3/GFP were obtained. After purification, the above DNA fragments were microinjected into the pre-nuclei of the mice fertilized eggs and transgenic mice were generated, with an integration rate of 10.89%. The green fluorescence protein(GFP) expression in many transgenic mouse tissues was determined by FACS analysis. The results showed that the HS2 and 1.7 kb of β-globin gene promoter were sufficient for the erythroid-specific expression of β-globin gene. The GFP expression of different recombinant constructs was also analyzed in blood of all the transgenic mice with FACS. The results indicated that HS2 and HS3 had the same enhancement activity on the regulation of β-globin gene expression. Moreover, these two elements showed a significant synergistic effect on gene expression at the transgenic mouse level, although the GFP expression varied largely among different transgenic mouse litters.     

Cloning of a down-regulated gene encoding small GTP binding protein in hybrid wheat

Previous studies showed that differential gene expression between wheathybrids and their parents was responsible for the heterosis. To provide an insight into the molecular basis of wheat heterosis, one cDNA, designated TaRab, was identified from the cDNA library of wheat seedling leaves. The sequence comparison in GenBank revealed that TaRab is homologous to a group of genes encoding Rab-GTP binding protein. Semi-quantitative RT-PCR analysis indicated that TaRab was expressed in all plant tissues examined, but at slightly higher level in leaves. Further analysis exhibited that TaRab displayed lower expression in hybrid than in its patents in both roots and leaves, which was in agreement with the original results of suppression subtractive hybridization. TaRab was located on chromosome 7B and C-7DS5-0.36 by in silico mapping. The relationship between differential expression of TaRab and the molecular basis of wheat heterosis was also discussed.     

Molecular cloning and characterization of a cotton phosphoenolpyruvate carboxylase gene

Phosphoenolpyruvate carboxylase （PEPC） plays diverse physiological functions during plant development. In this study, a new phos- phoenolpyruvate carboxylase gene GhPEPC2 is isolated from cotton （Gossypium hirsutum cv, zhongrnian 35） by RACE-PCR, The cloned cDNA of GhPEPC2 is 3364 bp in length, and has an open reading frame of 2913 bp, encoding for 971 putative amino acids with a calculated molecular mass of 110,6 kD and pI of 5,56. The deduced amino acid sequence of GhPEPC2 shares high similarity with other reported plant PEPCs, Southern blot analysis indicates that the cotton PEPC exists as a small gene family and the GhPEPC2 might have two copies in the cotton genome, The semi-quantitative RT-PCR reveals that GhPEPC2 constitutively expresses in all the tissues of cot- ton and accumulated highly in roots, flowers and embryos but relatively low in stems and fibers, In addition, the recombinant GhPEPC2 has been purified by expressing it in Escherichia coli and the catalytic properties of it were also investigated. The results showed that GhPEPC2 is a typical C3 PEPC with a higher Km （83,6 p.M） and lower Vmax （8,0 p.mol min^-1 mg^-1） compared with the C3 PEPCs previously reported.