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RNAseq - Alignment and differential expression analysis

Title: GE7334
Project: (none)
Started on: 4/1/2024 11:48:24
Hostname: login7.ufhpc
Run directory: /blue/licht/runs/Evans-MDS/GE7334/GE7334
Configuration GE7334.conf
Table of contents:
  1. Input data
  2. Trimming and quality control
  3. Alignment to transcriptome
  4. Genome coverage
  5. Expression analysis - quantification
  6. Differential expression - protein-coding genes
  7. Differential expression - all genes
  8. Differential expression - isoform level
  9. Differential expression - combined files
  10. MultiQC report
  11. UCSC hub
  12. Methods summary
1. Input data
The following table summarizes the samples, conditions, and contrasts in this analysis. A readset is either a single fastq file or a pair of fastq files (for paired-end sequencing).

CategoryData
Summary of input data
Reference genome:mm10
Experimental conditions:Parental, KMT2C_KO, DNMT3A_KO, KMT2C_DNMT3A_KO
Contrasts:KMT2C_KO vs. Parental, DNMT3A_KO vs. Parental, KMT2C_DNMT3A_KO vs. Parental, KMT2C_DNMT3A_KO vs. KMT2C_KO, KMT2C_DNMT3A_KO vs. DNMT3A_KO
Number of samples12
Sequencing data data
Total number of reads:518,208,135
Average reads per sample:43,184,011
Table 1. Summary of input data



ConditionSampleNumber of reads% Reads
ParentalP238,386,9467.41%
P338,850,6727.50%
P441,102,9127.93%
KMT2C_KOK346,438,4098.96%
K448,825,7669.42%
K549,734,7639.60%
DNMT3A_KOS4743,393,1258.37%
S5347,441,2829.15%
S6539,344,3007.59%
KMT2C_DNMT3A_KOS141,391,5097.99%
S1141,224,4947.96%
S6642,073,9578.12%
Table 2. Number of reads in each sample.

2. Trimming and quality control
The input sequences were trimmed using fastp (version 0.23.4). The following table provides links to the quality control reports after trimming, as well as the number of reads in the trimmed files.

SampleReadsetReads before trimReads after trimQC after trim% Retained
P2P2_r138,386,94632,414,933P2_r184.44%
P3P3_r138,850,67232,713,174P3_r184.20%
P4P4_r141,102,91234,661,387P4_r184.33%
K3K3_r146,438,40939,375,777K3_r184.79%
K4K4_r148,825,76641,304,349K4_r184.60%
K5K5_r149,734,76342,098,734K5_r184.65%
S47S47_r143,393,12536,750,558S47_r184.69%
S53S53_r147,441,28240,275,450S53_r184.90%
S65S65_r139,344,30033,494,534S65_r185.13%
S1S1_r141,391,50934,922,393S1_r184.37%
S11S11_r141,224,49434,734,268S11_r184.26%
S66S66_r142,073,95735,933,262S66_r185.40%
Table 3. Number of reads in input files and links to QC reports.

3. Alignment to transcriptome
The input sequences were aligned to the mm10 transcriptome using 2.7.11b. The following table reports the number of alignments to the genome and the transcriptome for each sample. Please note that the number of alignments will in general be higher than the number of reads because the same read may align to multiple isoforms of the same gene. The WIG files can be uploaded to the UCSC Genome Browser as custom tracks.

SampleInput readsGenome alignmentsGenome alignment rateTranscriptome alignmentsTranscriptome alignment rateAlignment report
P232,414,93363,581,5831.9624,063,73774.24%P2.star/Log.final.out
P332,713,17465,479,0782.0023,821,28572.82%P3.star/Log.final.out
P434,661,38769,171,9662.0025,420,51173.34%P4.star/Log.final.out
K339,375,77780,177,8082.0429,563,81175.08%K3.star/Log.final.out
K441,304,34982,986,4682.0131,384,82975.98%K4.star/Log.final.out
K542,098,73483,489,4821.9832,009,37376.03%K5.star/Log.final.out
S4736,750,55870,114,6851.9127,230,99574.10%S47.star/Log.final.out
S5340,275,45079,433,1021.9730,396,05575.47%S53.star/Log.final.out
S6533,494,53463,695,8881.9024,024,52271.73%S65.star/Log.final.out
S134,922,39369,677,7522.0025,231,52172.25%S1.star/Log.final.out
S1134,734,26868,503,1411.9725,759,00574.16%S11.star/Log.final.out
S6635,933,26272,960,5472.0326,917,40874.91%S66.star/Log.final.out
Table 4. Number of alignments to genome and transcriptome.

4. Genome coverage
The following table reports the overall and effective genome coverage in each sample. The Total nt column reports the total number of nucleotides sequenced, i.e. the number of aligned reads times the length of each read. Coverage is this number divided by the size of the genome. Effective bp reports the number of bases in the genome having coverage greater than 5, and the Effective Perc column shows what percentage this is of the genome size. Note that, especially in the case of RNA-seq, the effective genome size may be much smaller than the full size. Eff Coverage is the average coverage over the effectively covered fraction of the genome.

NameTotal ntCoverageEffective bpEffective PercEff Coverage
P242,068,204,70015.46415,993,89115.30%101.13
P345,685,614,71216.79430,722,89115.80%106.07
P450,386,959,60418.52432,109,20915.90%116.61
K358,706,137,15021.57452,606,30116.60%129.71
K457,789,012,69621.23443,156,48816.30%130.40
K559,880,140,99222.00447,318,41316.40%133.86
S4747,466,613,29017.45422,294,23515.50%112.40
S5356,097,156,08720.61434,528,65816.00%129.10
S6538,704,866,28314.23414,110,88615.20%93.46
S139,831,336,92814.64411,031,46315.10%96.91
S1150,613,812,68618.59435,039,65016.00%116.34
S6650,003,002,09518.38436,380,35316.00%114.59
Table 5. Genome coverage by sample.

The following table reports the overall and effective genome coverage in each condition.

NameTotal ntCoverageEffective bpEffective PercEff Coverage
Parental133,977,263,44449.21494,669,15218.20%270.84
KMT2C_KO00.0000.00%0.00
DNMT3A_KO138,164,129,21050.75493,208,57518.10%280.13
KMT2C_DNMT3A_KO136,135,946,42649.97507,187,82818.60%268.41
Table 6. Genome coverage by condition

File: GE7334.sample.cov.xlsx
Size: 43.31 kB
Description: Per-chromosome coverage data, by sample.

File: GE7334.cond.cov.xlsx
Size: 16.07 kB
Description: Per-chromosome coverage data, by condition.

5. Expression analysis - quantification
Gene and transcript expression values were quantified using RSEM v1.3.1. The following files contain the raw FPKM values for all genes/transcripts in all samples. NOTE: these values are not normalized yet, please apply the appropriate normalization before using them in analysis.
File: genes.rawmatrix.csv
Size: 3.93 MB
Description: Matrix of FPKM values for all genes in all samples.

File: transcripts.rawmatrix.csv
Size: 10.38 MB
Description: Matrix of FPKM values for all transcripts in all samples.

File: genes.xpra.txt
Size: 3.17 MB
Description: Counts table suitable for ExpressAnalyst.

The following scatterplots show the level of similarity between replicates of the same condition.


Principal Component Analysis on raw (un-normalized) expression data. Click on the thumbnail to display the full-size image.

(png format, 83.93 kB)


The following image displays the Multi-Dimensional Scaling (MDS) plot for the raw (un-normalized) expression data. Click on the thumbnail to display the full-size image.
6. Differential expression - protein-coding genes
Differential gene expression was analyzed using DESeq2. The following table reports the number of differentially expressed genes in each contrast with abs(log2(FC)) >= 1.0 and FDR-corrected P-value <= 0.05. The files under the Table heading contain the log2(FC) and P-value of all significant genes, while the files under the Expressions heading contain normalized expression values for the significant genes in all replicates of the two conditions being compared. The lists of differentially expressed genes for all contrasts can also be downloaded as a single Excel file using the link below.

TestControlTotalOverexpressedUnderexpressedTableExpressions
KMT2C_KOParental14113KMT2C_KO.vs.Parental.codinggeneDiff.csvKMT2C_KO.vs.Parental.gmatrix.csv
DNMT3A_KOParental303DNMT3A_KO.vs.Parental.codinggeneDiff.csvDNMT3A_KO.vs.Parental.gmatrix.csv
KMT2C_DNMT3A_KOParental1,030301729KMT2C_DNMT3A_KO.vs.Parental.codinggeneDiff.csvKMT2C_DNMT3A_KO.vs.Parental.gmatrix.csv
KMT2C_DNMT3A_KOKMT2C_KO987326661KMT2C_DNMT3A_KO.vs.KMT2C_KO.codinggeneDiff.csvKMT2C_DNMT3A_KO.vs.KMT2C_KO.gmatrix.csv
KMT2C_DNMT3A_KODNMT3A_KO964308656KMT2C_DNMT3A_KO.vs.DNMT3A_KO.codinggeneDiff.csvKMT2C_DNMT3A_KO.vs.DNMT3A_KO.gmatrix.csv
Table 7. Results of gene-level differential expression analysis.

File: GE7334-codingdiff.xlsx
Size: 222.64 kB
Description: Excel file containing differentially expressed genes for all contrasts (one sheet per contrast). Only includes protein-coding genes.

File: GE7334-allcodingdiff.xlsx
Size: 3.65 MB
Description: Excel file containing differential expression values for all tested genes in all contrasts (one sheet per contrast). Only includes protein-coding genes. Note: genes with very low average expression in all conditions were removed.

File: GE7334.g.deseq2norm.xlsx
Size: 2.18 MB
Description: Excel file containing normalized (DESeq2) expression values for all protein-coding genes in all conditions. Note: genes with very low average expression in all conditions were removed.


Principal Component Analysis on normalized expression data. Click on the thumbnail to display the full-size image.

(png format, 85.59 kB)


The following image displays the Multi-Dimensional Scaling (MDS) plot for the normalized expression data. In this plot, relative distances between samples reflect the similarity of their gene expression profiles. Ideally, replicates of the same condition should be close together, and well separated from other conditions.

Volcano plots for all contrasts. Use the menu to select a contrast.

7. Differential expression - all genes
The following table reports results from the same differential analysis as above, but includes all biotypes instead of coding genes only.

TestControlTotalOverexpressedUnderexpressedTableExpressions
KMT2C_KOParental14113KMT2C_KO.vs.Parental.geneDiff.csvKMT2C_KO.vs.Parental.gmatrix.csv
DNMT3A_KOParental303DNMT3A_KO.vs.Parental.geneDiff.csvDNMT3A_KO.vs.Parental.gmatrix.csv
KMT2C_DNMT3A_KOParental1,159360799KMT2C_DNMT3A_KO.vs.Parental.geneDiff.csvKMT2C_DNMT3A_KO.vs.Parental.gmatrix.csv
KMT2C_DNMT3A_KOKMT2C_KO1,102375727KMT2C_DNMT3A_KO.vs.KMT2C_KO.geneDiff.csvKMT2C_DNMT3A_KO.vs.KMT2C_KO.gmatrix.csv
KMT2C_DNMT3A_KODNMT3A_KO1,057360697KMT2C_DNMT3A_KO.vs.DNMT3A_KO.geneDiff.csvKMT2C_DNMT3A_KO.vs.DNMT3A_KO.gmatrix.csv
Table 8. Results of gene-level differential expression analysis (all biotypes).

File: GE7334-genediff.xlsx
Size: 250.23 kB
Description: Excel file containing differentially expressed genes for all contrasts (one sheet per contrast). Includes all genes and pseudo-genes.

File: GE7334-allgenediff.xlsx
Size: 4.24 MB
Description: Excel file containing differential expression values for all genes in all contrasts (one sheet per contrast). Includes all genes and pseudo-genes.

File: GE7334-allExpressions.xlsx
Size: 2.54 MB
Description: Excel file containing normalized (RSEM) expression values for all genes in all conditions.

8. Differential expression - isoform level
The following table reports the number of differentially expressed isoforms in each contrast with abs(log2(FC)) >= 1.0 and FDR-corrected P-value <= 0.05. The lists of differentially expressed isoforms for all contrasts can also be downloaded as a single Excel file using the link below.

TestControlTot isoformsOverexpressedUnderexpressedTableExpressions
KMT2C_KOParental673334KMT2C_KO.vs.Parental.isoDiff.csvKMT2C_KO.vs.Parental.imatrix.csv
DNMT3A_KOParental793346DNMT3A_KO.vs.Parental.isoDiff.csvDNMT3A_KO.vs.Parental.imatrix.csv
KMT2C_DNMT3A_KOParental1,7866091,177KMT2C_DNMT3A_KO.vs.Parental.isoDiff.csvKMT2C_DNMT3A_KO.vs.Parental.imatrix.csv
KMT2C_DNMT3A_KOKMT2C_KO1,6816021,079KMT2C_DNMT3A_KO.vs.KMT2C_KO.isoDiff.csvKMT2C_DNMT3A_KO.vs.KMT2C_KO.imatrix.csv
KMT2C_DNMT3A_KODNMT3A_KO1,6075631,044KMT2C_DNMT3A_KO.vs.DNMT3A_KO.isoDiff.csvKMT2C_DNMT3A_KO.vs.DNMT3A_KO.imatrix.csv
Table 9. Results of isoform-level differential expression analysis.

File: GE7334-isodiff.xlsx
Size: 421.92 kB
Description: Excel file containing differentially expressed isoforms for all contrasts (one sheet per contrast).

File: GE7334-allisodiff.xlsx
Size: 10.32 MB
Description: Excel file containing differential expression values for all isoforms in all contrasts (one sheet per contrast).

9. Differential expression - combined files
The following file contains merged differential expression data. The first sheet contains fold changes for all genes that were found to be differentially expressed in at least one contrast. The second and third sheets contain the same information for coding genes only, and all transcripts.
File: GE7334-merged.allDiff.xlsx
Size: 460.87 kB
Description: Merged fold changes for all differentially expressed genes, coding genes, and transcripts respectively.

10. MultiQC report
MultiQC is a general Quality Control tool for a large number of bioinformatics pipelines. The report on this analysis (generated using MultiQC version 1.12) is available here:

MultiQC report
11. UCSC hub

UCSC Genome Browser: use the previous link to display the data tracks automatically, or copy the the URL https://bw:bw@data.rc.ufl.edu/secure/icbr/GE7334//GE7334/hub/hub.txt and paste it into the "My Hubs" form in this page.

WashU EpiGenome Browser: use the previous link to display the data tracks automatically, or copy the following URL into the "Datahub by URL Link" field: https://bw:bw@data.rc.ufl.edu/secure/icbr/GE7334//GE7334/hub/hub.json.

12. Methods summary

Trimming and QC on short reads were performed by fastp (v 0.23.4) [1].

The reads were aligned to the transcriptome using STAR version 2.7.11b [2].

Transcript abundance was quantified using RSEM (RSEM v1.3.1) [3].

Differential expression analysis was performed using DESeq2 [4], with an FDR-corrected P-value threshold of 0.05. The output files were further filtered to extract transcripts showing a 2.0-fold change in either direction. Results were reported for protein-coding genes only, and for all transcript types.


References

  1. Shifu Chen, Yanqing Zhou, Yaru Chen, Jia Gu; fastp: an ultra-fast all-in-one FASTQ preprocessor, Bioinformatics, Volume 34, Issue 17, 1 September 2018, Pages i884–i890 | doi: 10.1093/bioinformatics/bty560
  2. Dobin A, Davis CA, Schlesinger F, Drenkow J, Zaleski C, Jha S, Batut P, Chaisson M, Gingeras TR (2013). STAR: ultrafast universal RNA-seq aligner. Bioinformatics. 29(1):15-21 | doi: 10.1093/bioinformatics/bts635
  3. Li B and Dewey CN (2011). RSEM: accurate transcript quantification from RNA-Seq data with or without a reference genome. BMC Bioinformatics 12:323 | doi: 10.1186/1471-2105-12-323
  4. Love MI, huber W, Anders S. Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2. Genome Biology, 15,550 (2014). | doi: 10.1186/s13059-014-0550-8



Completed: 4-1-2024@11:50
© 2024, A. Riva, University of Florida.