Question: Which kind of microRNAs expression are measured in TCGA?
gravatar for jack
5.3 years ago by
jack790 wrote:

Hi all,

I have download the mRNA and microRNA NGS data from TCGA for BRCA.
for downloading the microRNA data, I choosed the miRNASeq from filter setting.
Now I have the expression level of miRNA in diffrent samples.
The question for is that, which kind of microRNA they are quantified ? is it all mature miRNA ? or mirna precursor are also there ? They seqenced miRNA which they got from gel electrophoresis ?(to be sure that, all of them have same length in case of mature miRNA).
But when I look at the miRNA IDs; there is some problem:
for example : they have expression level for hsa-mir-135a-2 , which when I search for it in miRBase, it's stem loop and it's mature form in miRbase is hsa-miR-135a-5p . so now I'm really in trouble to undersrand that expression level of which type of miRNA are quantified ?

would someone clarify it more ?

ADD COMMENTlink modified 23 months ago by gaoteng30 • written 5.3 years ago by jack790

You asked the question I would like to know the answer

ADD REPLYlink written 2.0 years ago by a51151234590
gravatar for Ying W
5.3 years ago by
Ying W3.9k
South San Francisco, CA
Ying W3.9k wrote:

Please read through the experimental protocol related to miRNA dataset that you have to determine what type of miRNA is captured. I would guess that they are using random-hexamer priming on RNA isolated from patient tissue after rRNA depletion. This technique would not allow for differentiation between phosphorylated and non-phosphorylated forms. Keep in mind miRNA-seq assays all RNAs at once so they are not selecting a miRNA to focus on / cutting out size from gel

ADD COMMENTlink modified 5.3 years ago • written 5.3 years ago by Ying W3.9k

Thanks Yving, I looked at the META data file. they describe like this : "

Ligation of linkers and reverse transcription of small RNAs    "PCR with sequencing primers, size fractionation"    Sequencing on Illumina GAIIx    Alignment of reads to reference genome    Read counts per mirna isoform    Normalized expression per mirna gene

SDRF Files"


So what should I do? Now the conclusion is that; the miRNA expression level in TCGA data contain all miRNAs?(miRNA stem loop, miRNA precursors, mature miRNA )    



ADD REPLYlink written 5.3 years ago by jack790
gravatar for gaoteng
23 months ago by
gaoteng30 wrote:

I believe that each mature transcript (e.g. hsa-miR-135a-5p, hsa-miR-135a-3p) are identified by a mirBase ID with prefix MIMAT. I think to get the mature transcript expressions, you need to parse the data from TCGA miRNASeq isoform quantification files (ending with .mirbase21.isoforms.quantification.txt).

I think the correct way to process the isoform data is to take the max or sum for all counts associated with each mature transcript ID. Here is my script:

Please correct me if I'm wrong!

ADD COMMENTlink modified 23 months ago • written 23 months ago by gaoteng30
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