Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Variance in microarray studies has been widely discussed as a critical topic of the identification of differentially expressed gene; however, few studies have addressed the influence of estimating variance. To break intra- and inter-individual variance in clinical studies down to three levels: technical, anatomic, and individual, we designed experiments and algorithms to investigate three forms of variances. As a case study, a group of “inter-individual variable genes” were identified to exemplify the influence of underestimated variance on the statistical and biological aspects in identification of differentially expressed genes. Our results showed that inadequate estimation of variance inevitably led to the inclusion of non-statistically significant genes into those listed as significant, thereby interfering with the correct prediction of biological functions. Applying a higher cutoff value of fold changes in the selection of significant genes reduce/eliminate the effects of underestimated variance. Our data demonstrates that an appropriate evaluation of variance is critical in selecting significant genes of differential expression. If the estimation of precise variance has not been adequately considered in the experimental design, using a higher fold change criteria is one possible solution to overcome the difficulties associated with the identification of significant genes, but it paid by losing the number of selected genes.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
Project description:Variance in microarray studies has been widely discussed as a critical topic of the identification of differentially expressed gene; however, few studies have addressed the influence of estimating variance. To break intra- and inter-individual variance in clinical studies down to three levels: technical, anatomic, and individual, we designed experiments and algorithms to investigate three forms of variances. As a case study, a group of “inter-individual variable genes” were identified to exemplify the influence of underestimated variance on the statistical and biological aspects in identification of differentially expressed genes. Our results showed that inadequate estimation of variance inevitably led to the inclusion of non-statistically significant genes into those listed as significant, thereby interfering with the correct prediction of biological functions. Applying a higher cutoff value of fold changes in the selection of significant genes reduce/eliminate the effects of underestimated variance. Our data demonstrates that an appropriate evaluation of variance is critical in selecting significant genes of differential expression. If the estimation of precise variance has not been adequately considered in the experimental design, using a higher fold change criteria is one possible solution to overcome the difficulties associated with the identification of significant genes, but it paid by losing the number of selected genes. A total of 11 normal placenta tissues obtained from 9 healthy individuals with term pregnancies, whom underwent cesarean section without labor pain. The first sample group (G1) was composed of samples 1 to 9 of nine individuals. The second sample group (G2) contained 8-1, 8-2 and 8-3, which were three different placental tissues taken from the same individual. The third sample group (G3) consisted of two technical replicates, 8-3_1 and 8-3_2, using the identical RNA pool. Sample 8-3 is estimated by sample 8-3_1 and 8-3_2. Sample 8 is estimated by sample 8-1, 8-2 and 8-3.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs. One-condition experment, gene expression of 3A6