Cells that are differentiated express the genes that are necessary for their own usage. I've heard that some cell type expresses about 90% of 30,000 proteins that are encoded in the genome. Can anybody tell me what this cell type is?

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    $\begingroup$ Can you point us to a source that says that? $\endgroup$ – Bryan Krause Jun 9 '17 at 15:43
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    $\begingroup$ I'm thinking of thymic medullary cells, but I don't know how many genes they express. $\endgroup$ – canadianer Jun 9 '17 at 16:05
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    $\begingroup$ I've rolled your edit back because it completely changes the meaning of the question and renders the answer irrelevant. If you have a different question, ask it in a new post. $\endgroup$ – canadianer Jun 10 '17 at 3:24
  • $\begingroup$ I'm voting to close this question because the asker stubbornly insists on edits that change the question to something meaningless. $\endgroup$ – Bryan Krause Jun 11 '17 at 5:12
  • $\begingroup$ Please stop editing the question so that the answer gets meaningless and open a new question instead. I will roll back it to the last version where answer makes sense and then lock it. $\endgroup$ – Chris Jun 11 '17 at 15:24

Well, I found this paper:

Danan-Gotthold M, Guyon C, Giraud M, Levanin EY, Abramson J. 2016. Extensive RNA editing and splicing increase immune self-representation diversity in medullary thymic epithelial cells. Genome Biol 17:219.

Medullary thymic epithelial cells [mTECs] express ~85 % of the entire coding genome

...to better determine the fraction of genes expressed in mTECs and other mouse tissues, we took advantage of RNA-seq technology... The analysis... revealed that most of the tissues [see below for those tested] express 12,000–14,000 genes (i.e. 60–65 % of the coding genome). The lung and two immunologically privileged sites, brain and testis, were the only tissues that expressed a larger fraction of the genome, in the range of 70–75 %... In line with other recently published studies, the mTEChi population expressed nearly 18,000 genes, which represents ~85 % of the coding genome, while Aire-deficient mTECs (AireKO) expressed approximately 15,000 genes, suggesting that Aire is responsible for the induction of ~3000 genes in mTECs. Interestingly, even in the absence of Aire, the mTECs expressed a relatively large fraction of the genome (~75 %), considerably exceeding the overall genome expression in other peripheral tissues. Interestingly, neither [cortical thymic epithelial cells] nor [skin epithelial cells] demonstrated higher overall genome expression than other tissues, suggesting that promiscuous gene expression is indeed unique to the mTECs population.

These cells express such a wide complement of proteins because they are involved in T-cell maturation, specifically negative selection.

List of tissues tested in the study:

brain, testes, liver, kidney, lung, colon, skeletal muscle, spleen, cortical thymic epithelial cells, skin epithelial cells


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