C2_combined_R2.fastq.gz
Glucocorticoid steroid hormones play essential roles for maturation and growth of many fetal organs including the lung and heart, yet the kidney-specific roles are not well characterised. Glucocorticoids activate the intracellular glucocorticoid receptor (GR) that acts primarily as nuclear transcriptional regulators. We analysed the effect of loss of GR expression on the fetal kidney transcriptome at E18.5 by RNA sequencing. Total RNA was extracted from control (n=4) and GR-null (n=3) kidneys. Loss of GR expression resulted in 2473 differentially expressed genes (FDR < 0.05), 288 genes with absolute LogFC > 1 & FDR < 0.05, which identified 16 upregulated and 25 downregulated primary ciliary genes (FDR < 0.05). Primary cilia are cell signalling and environment sensing organelles that protrude from cell membranes and play important roles during embryogenesis and tissue homeostasis. Little is known of the cellular pathways regulating ciliogenesis. Our findings indicate a role of glucocorticoid signalling in primary cilia formation in renal tubular cells of the developing mouse kidney.
Total RNA was isolated from embryonic kidneys using TRIzolTM reagent (Invitogen, USA) according to the manufacturer’s instructions. Total RNA was analysed using a Bioanalyzer 2100 (Agilent Technologies, USA) and Next generation RNA sequencing (NGS RNA-seq) was performed by Genewiz Biotechnology, Suzhou, China. RNA sequencing (20 million reads) was performed on the Illumina Hiseq platform, in a 2 x 150 bp paired-end format.
Total RNA of each sample was extracted using TRIzol reagent (Invitrogen) following the manufacturer's instructions.Next generation sequencing library preparations were constructed according to the manufacture's protcol. The The poly(A) mRNA isolation was performed using Poly(A) mRNA Magnetic Isolation Module or rRNA removal Kit. The mRNA fragmentation and priming was performed using First Strand Synthesis Reaction Buffer and Random Primers. First strand cDNA was synthesized using ProtoScript II Reverse Transcriptase and the second-strand cDNA was synthesized using Second Strand Synthesis Enzyme Mix. The purified double stranded cDNA by beads was then treated with End Prep Enzyme Mix to repair both ends and add a dA tailing in one reaction, followed by a T-A ligation to add adaptors to both ends. Size selection of Adaptor ligated DNA was then performed using beads, and fragments of ~420 bp (with the approximate insert size of 300 bp) were recovered. Each sample was then amplified by PCR for 13 cycles using P5 and P7 primers, with both primers carrying sequences which can anneal with flow cell to perform bridge PCR and P7 primer carrying a six-base index allowing for multiplexing. The PCR products were cleaned up using beads, validated using an Qsep100 (Bioptic, Taiwan, China), and quantified by Qubit3.0 Fluorometer (Invitrogen, Carlsbad, CA, USA).
In order to remove technical sequences, including adapters, polymerase chain reaction (PCR) primers, or fragments thereof, and quality of bases lower than 20, pass filter data of fastq format were processed by Cutadapt (V1.9.1) to be high quality clean data.
Firstly, reference genome sequences and gene model annotation files of relative species (GRm39.97) were downloaded from genome website, such as UCSC, NCBI, ENSEMBL. Secondly, Hisat2 (v2.0.1) was used to index reference genome sequence. Finally, clean data were aligned to reference genome via software Hisat2 (v2.0.1).
In the beginning transcripts in fasta format are converted from known gff annotation file and indexed properly. Then, with the file as a reference gene file, HTSeq (v0.6.1) estimated gene and isoform expression levels from the pair-end clean data.
