siRNA / miRNA gene silencing Human HT-1376

Cell Invasion or Cell Migration assays are technically challenging to set up as the gradient between the two compartments equilibrates in time during the assay. It is also problematic to view cells and for cells to migrate through a non-physiologic polycarbonate or polypropylene filter. Care must be taken while loading the well with cells to form a single cell suspension. Precaution must be taken while trypsinization (under-trypsinization can lead to cell clumping while over-trypsinization could strip off adhesion molecules necessary for migration). This leads to difficulty in getting significant results, when only small numbers of cells cross the filter or when the distribution and/or staining of the cells is uneven.

Get tips on using FlexiTube GeneSolution GS27279 for Tnfrsf12a to perform siRNA / miRNA gene silencing Mouse - B16-BL6 FN14/Tnfrsf12a

Cell cytotoxicity assays measure the ability of certain compounds or chemical mediators to reduce the viability of the cells. The term cell cytotoxicity assay can sometimes be used interchangeably with cell proliferation assay. Healthy living cells can be identified by the use of formazan dyes, protease biomarkers or by measuring ATP content. The formazan dyes are chromogenic products formed by the reduction of tetrazolium salts by dehydrogenases, such as lactate dehydrogenase (LDH) and reductases that are released during cell death. Common tetrazolium salts include INT, MTT, MTS and XTT. Cell cytotoxicity can also be measured by using the SRB and WST-1 assays. These assays can usually be used in a high-throughput fashion and can be quantitated by measuring absorbance, colorimetry or luminescence. All these assays require similar numbers of cell plating at the initiation, a time course of treatment with the cytotoxic agent and at least triplicates for each condition at every point of analysis. Cell shrinkage, plasma membrane blebbing, cell detachment, externalization of phosphatidylserine, nuclear condensation and ultimately DNA fragmentation are well-described features of apoptosis. The assays that rely on cell membrane integrity for their function, may not be able to quantify early apoptosis. Therefore, in order to distinguish early apoptotic vs. late apoptotic or necrotic cells, additional flow cytometry techniques can be used. A combination of Annexin V and PI (propidium iodide) can be used to distinguish early (Annexin V+/PI-) and late apoptotic (Annexin V+/PI+) cells. Sometimes, caspase assays are used in order to differentiate the stages of apoptosis.

Short hairpin or small hairpin RNA (shRNA) is artificial RNA, which has a hairpin loop structure, and uses inherent microRNA (miRNA) machinery to silence target gene expression. This is called RNA interference (RNAi). These can be delivered via plasmids or viral/bacterial vectors. Challenges in shRNA-mediated gene silencing include: 1. Off-target silencing, 2. Packaging shRNA encoding lentivirus, and 3. Stable transduction in cells. RNAi have been designed to have anywhere from 19-27 bs, but the most effective design has 19 bp. In case commercial shRNAs are not available, potential target sites can be chosen within exon, 5’- or 3’ UTR, depending on which splice variants of the gene are desired. One should use the latest algorithms and choose at least two different sequences, targeting different regions, in order to have confidence in overcoming off-target effects. A BLAST search after selecting potential design will eliminate potential off-target sequences. For the second challenge, sequencing the vector using primers for either strand (50-100 bp upstream) is suggested, along with using enzymatic digestion on agarose gel for the vector. Next, once the shRNA-containing vector is packaged in a virus, it is important to check the viral titer before transduction. Finally, using a marker in the lentiviral vector (fluorescent protein or antibiotic resistance), along with qPCR for target gene expression can help in determining efficacy of transduction and shRNA on its target site.

Get tips on using SurePrint Human miRNA Microarrays to perform Microarray Human - Endometrial stromal cells miRNA-expression array (labelled)

Get tips on using 3D-Gene® Mouse miRNA Oligo chip (ver.21) to perform Microarray Gene expression arrays - Mouse liver tissue Cyanine-3-CTP

Get tips on using MISSION® esiRNA_esiRNA targeting mouse Lrp5 (esiRNA1) to perform siRNA / miRNA gene silencing Mouse - MLO‐Y4 Lrp5

Get tips on using MISSION® esiRNA_esiRNA targeting mouse Lrp6 (esiRNA1) to perform siRNA / miRNA gene silencing Mouse - MLO‐Y4 Lrp6

Get tips on using Absolutely RNA miRNA Kit to perform RNA isolation / purification Cells - immortalized HT-29