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Dicer up-regulation by inhibition of specific proteolysis in differentiating monocytic cells.

Basavarajappa, Devaraj ; Uebbing, Stella ; Kreiss, Marius ; Lukic, Ana ; Suess, Beatrix ; Steinhilber, Dieter ; Samuelsson, Bengt ; Rådmark, Olof (2020):
Dicer up-regulation by inhibition of specific proteolysis in differentiating monocytic cells.
In: Proceedings of the National Academy of Sciences of the United States of America, 117 (15), pp. 8573-8583. ISSN 1091-6490,
DOI: 10.1073/pnas.1916249117,
[Article]

Abstract

Dicer is a ribonuclease III enzyme in biosynthesis of micro-RNAs (miRNAs). Here we describe a regulation of Dicer expression in monocytic cells, based on proteolysis. In undifferentiated Mono Mac 6 (MM6) cells, full-length Dicer was undetectable; only an ∼50-kDa fragment appeared in Western blots. However, when MM6 cells were treated with zymosan or LPS during differentiation with TGF-β and 1,25diOHvitD3, full-length Dicer became abundant together with varying amounts of ∼170- and ∼50-kDa Dicer fragments. Mass spectrometry identified the Dicer fragments and showed cleavage about 450 residues upstream from the C terminus. Also, PGE (prostaglandin E2) added to differentiating MM6 cells up-regulated full-length Dicer, through EP2/EP4 and cAMP. The TLR stimuli strongly induced miR-146a-5p, while PGE increased miR-99a-5p and miR-125a-5p, both implicated in down-regulation of TNFα. The Ser protease inhibitor AEBSF (4-[2-aminoethyl] benzene sulfonyl fluoride) up-regulated full-length Dicer, both in MM6 cells and in primary human blood monocytes, indicating a specific proteolytic degradation. However, AEBSF alone did not lead to a general increase in miR expression, indicating that additional mechanisms are required to increase miRNA biosynthesis. Finally, differentiation of monocytes to macrophages with M-CSF or GM-CSF strongly up-regulated full-length Dicer. Our results suggest that differentiation regimens, both in the MM6 cell line and of peripheral blood monocytes, inhibit an apparently constitutive Dicer proteolysis, allowing for increased formation of miRNAs.

Item Type: Article
Erschienen: 2020
Creators: Basavarajappa, Devaraj ; Uebbing, Stella ; Kreiss, Marius ; Lukic, Ana ; Suess, Beatrix ; Steinhilber, Dieter ; Samuelsson, Bengt ; Rådmark, Olof
Title: Dicer up-regulation by inhibition of specific proteolysis in differentiating monocytic cells.
Language: English
Abstract:

Dicer is a ribonuclease III enzyme in biosynthesis of micro-RNAs (miRNAs). Here we describe a regulation of Dicer expression in monocytic cells, based on proteolysis. In undifferentiated Mono Mac 6 (MM6) cells, full-length Dicer was undetectable; only an ∼50-kDa fragment appeared in Western blots. However, when MM6 cells were treated with zymosan or LPS during differentiation with TGF-β and 1,25diOHvitD3, full-length Dicer became abundant together with varying amounts of ∼170- and ∼50-kDa Dicer fragments. Mass spectrometry identified the Dicer fragments and showed cleavage about 450 residues upstream from the C terminus. Also, PGE (prostaglandin E2) added to differentiating MM6 cells up-regulated full-length Dicer, through EP2/EP4 and cAMP. The TLR stimuli strongly induced miR-146a-5p, while PGE increased miR-99a-5p and miR-125a-5p, both implicated in down-regulation of TNFα. The Ser protease inhibitor AEBSF (4-[2-aminoethyl] benzene sulfonyl fluoride) up-regulated full-length Dicer, both in MM6 cells and in primary human blood monocytes, indicating a specific proteolytic degradation. However, AEBSF alone did not lead to a general increase in miR expression, indicating that additional mechanisms are required to increase miRNA biosynthesis. Finally, differentiation of monocytes to macrophages with M-CSF or GM-CSF strongly up-regulated full-length Dicer. Our results suggest that differentiation regimens, both in the MM6 cell line and of peripheral blood monocytes, inhibit an apparently constitutive Dicer proteolysis, allowing for increased formation of miRNAs.

Journal or Publication Title: Proceedings of the National Academy of Sciences of the United States of America
Journal volume: 117
Number: 15
Divisions: 10 Department of Biology
10 Department of Biology > Synthetic Genetic Circuits
Date Deposited: 09 Apr 2020 05:28
DOI: 10.1073/pnas.1916249117
Identification Number: pmid:32220961
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