Six3 and Six6 are jointly required for the maintenance of multipotent retinal progenitors through both positive and negative regulation

Purpose: the goal of this experiment was to identify differentially expressed genes in Six3 null, Six6 null and Six3;Six6 compound null retinas by RNAsequencing. Method: Retinas were dissected out from the following E13.5 mouse embryos: 1) WT (Six3F/F; Six6+/+); 2) Six3 KO (Six3F/F; CAGGCre-ERTM; Six6+/+); 3) Six6 KO (Six3F/F; Six6–/–); 4) DKO (Six3F/F; CAGGCre-ERTM; Six6–/–). RNA was then extracted from the retinas and profiled using RNAsequencing. Results: RNA isolated from three pairs of retinas for each genotype group (181.2-792 ng, RIN>9) was used for library preparation using KAPA RNA HyperPrep Kit with RiboErase. Sequencing was run on Illumina HiSeq 2500 in 100-bp single-end high-output mode in the Einstein Epigenomics Core Facility. About 30 million reads were generated for each sample. Each genotype group initially had three biological replicates, but one Six6 KO replicate was later removed due to over duplication. After trimming adapters with Trim Galore (v. 0.3.7), RNA-Seq reads were aligned back to mouse genome mm10 using Tophat (v. 2.0.13). The number of reads mapped back to each gene was calculated with HTseq (v.0.6.1) using Refseq gene annotation (downloaded from the UCSC genome browser in 03/17). The Cuffdiff in Cufflinks package (v. 2.2.1) was used to generate FPKM values. We identified 13498 transcripts with FPKM value >1 in at least one of samples. Deseq2 was used to determine the differentially expressed genes (DEGs) with FDR less than 0.05 as a cutoff. Overall design: Three pairs of retinas from each genotype were analyzed (n=3 biological replicates). One Six6 KO sample was later removed due to high duplication. Six3KO, Six6KO and DKO samples were compared to WT Controls (Six3F/F) using DESeq2, respectively .

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Diacou R, Zhao Y, Zheng D, Cvekl A, Liu W