Transcription profiling by array of mouse to identify RNA bound to the TDP-43 ribonucleoprotein complex

In total 3 mice brain tissues were used for this experiment. Tissue from each mouse brain was divided for immunoprecipitation with 5ug of either rabbit anti-TDP-43 antibody (Abcam) or normal rabbit IgG (Sigma) .The antibodies were first incubated with the lysate overnight at 4 degrees C, after which 50 uL of protein G Dynabeads(tm) (Invitrogen(tm)) added and the solution incubated for 1 hour at 4 degrees C with rotation. Following several washing with washing buffer (Invitrogen(tm)), the protein-RNA complex was eluted from 20 uL of bead-protein complex using 10 uL of elution buffer (Invitrogen(tm)) and seperated on a 10% NuPage(tm) Bis-Tris gel (Invitrogen(tm)). RNA was isolated from the remaining 30 uL of protein-bead complex using TRIzol reagent (Invitrogen) followed by DNaseI treatment (Ambion). The TDP-43 immunoprecipitated RNA was converted to cDNA, fragmented and biotin labelled using WT cDNA synthesis & amplification kit and Terminal Labeling Kit (Affymetrix(tm)) for Affymetrix(tm) GeneChip(tm) Mouse Gene 1.0 ST and 3'-IVT expression analysis kit (Affymetrix(tm)) for GeneChip(tm) Mouse 430_2 arrays according to the standard protocol. Labelled RNA was hybridised to arrays in a hybridization oven (Affymetrix(tm)) at 45 degrees C rotating at 60 rpm for 17 hours and scanned using the Affymetrix(tm) GeneChip Scanner. Successful hybridisation to the microarray was checked using Expression Console software (Affymetrix(tm)) and the data (.CEL files) transferred to Partek Genomics Suite for statistical analysis. TDP-43 and IgG immunoprecipitated RNA samples were each hybridised to 3 GeneChip Mouse Gene 1.0 ST and 3 GeneChip Mouse 430 (n = 6 for each group).

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