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The Assembly of EDC4 and Dcp1a into Processing Bodies Is Critical for the Translational Regulation of IL-6.

Seto E, Yoshida-Sugitani R, Kobayashi T, Toyama-Sorimachi N - PLoS ONE (2015)

Bottom Line: In contrast, P-body assembly in response to oxidative stress or TLR4 stimulation was increased in M1-THPs as compared to M2-THPs.These results suggest that mRNA metabolism is controlled differently in M1-THPs and M2-THPs.Interestingly, knocking down EDC4 or Dcp1a, which are components of P-bodies, severely reduced the production of IL-6, but not TNF-α in M1-THPs without decreasing the amount of IL-6 mRNA.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Immunology and Inflammation, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan; Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Gunma, Japan.

ABSTRACT
Macrophages play critical roles in the onset of various diseases and in maintaining homeostasis. There are several functional subsets, of which M1 and M2 macrophages are of particular interest because they are differentially involved in inflammation and its resolution. Here, we investigated the differences in regulatory mechanisms between M1- and M2-polarized macrophages by examining mRNA metabolic machineries such as stress granules (SGs) and processing bodies (P-bodies). Human monocytic leukemia THP-1 cells cultured under M1-polarizing conditions (M1-THPs) had less ability to assemble oxidative-stress-induced SGs than those cultured under M2-polarizing conditions (M2-THPs). In contrast, P-body assembly in response to oxidative stress or TLR4 stimulation was increased in M1-THPs as compared to M2-THPs. These results suggest that mRNA metabolism is controlled differently in M1-THPs and M2-THPs. Interestingly, knocking down EDC4 or Dcp1a, which are components of P-bodies, severely reduced the production of IL-6, but not TNF-α in M1-THPs without decreasing the amount of IL-6 mRNA. This is the first report to demonstrate that the assembly of EDC4 and Dcp1a into P-bodies is critical in the posttranscriptional regulation of IL-6. Thus, improving our understanding of the mechanisms governing mRNA metabolism by examining macrophage subtypes may lead to new therapeutic targets.

No MeSH data available.


Related in: MedlinePlus

SG and P-body components are expressed in M1-THPs and M2-THPs.(A) M1-THPs and M2-THPs with no treatment (NT) or stimulated with LPS for 1, 4, 8, or 24 hours were harvested and subjected to semi-quantitative RT-PCR (A) and immunoblot analyses using antibodies against the SG or P-body components indicated; (B) β-actin served as a loading control.
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pone.0123223.g004: SG and P-body components are expressed in M1-THPs and M2-THPs.(A) M1-THPs and M2-THPs with no treatment (NT) or stimulated with LPS for 1, 4, 8, or 24 hours were harvested and subjected to semi-quantitative RT-PCR (A) and immunoblot analyses using antibodies against the SG or P-body components indicated; (B) β-actin served as a loading control.

Mentions: We next compared the expression levels of various SG and P-body components in M1-THPs and M2-THPs. We found no obvious differences in TIA1 or G3BP1 expression at either the transcriptional or protein level (Fig 4A and 4B), and the expression levels of these SG components were not affected by oxidative stress or by LPS stimulation. The levels of TTP, a zinc-finger-containing protein that promotes SG nucleation and the decay of AU-rich region (ARE)-containing mRNAs at P-bodies[32], increased in both M1-THPs and M2-THPs upon LPS stimulation. The most noticeable difference between M1-THPs and M2-THPs was in the expression levels of Dcp1a, an essential P-body component that also forms part of the decapping complex[22]. The Dcpla protein and mRNA levels were higher in M1-THPs than M2-THPs, and their expression in M1-THPs gradually increased during LPS stimulation (Fig 4A and 4B). This increase of Dcp1a in M1-THPs was consistent with the increased number of P-bodies in M1-THPs. When cells were treated with arsenite, a slow-migrating Dcp1a band was observed in both M1-THPs and M2-THPs (Fig 4B). This probably corresponded to a phosphorylated Dcp1a, since Dcp1a is known to undergo hyper-phosphorylation[41]. A slow-migrating band was not observed in LPS-treated cells. The protein level of Dcp2, a P-body component that catalyzes cytoplasmic mRNA decapping in conjunction with its coactivator Dcp1a[42], was similar in M1-THPs and M2-THPs.


The Assembly of EDC4 and Dcp1a into Processing Bodies Is Critical for the Translational Regulation of IL-6.

Seto E, Yoshida-Sugitani R, Kobayashi T, Toyama-Sorimachi N - PLoS ONE (2015)

SG and P-body components are expressed in M1-THPs and M2-THPs.(A) M1-THPs and M2-THPs with no treatment (NT) or stimulated with LPS for 1, 4, 8, or 24 hours were harvested and subjected to semi-quantitative RT-PCR (A) and immunoblot analyses using antibodies against the SG or P-body components indicated; (B) β-actin served as a loading control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430274&req=5

pone.0123223.g004: SG and P-body components are expressed in M1-THPs and M2-THPs.(A) M1-THPs and M2-THPs with no treatment (NT) or stimulated with LPS for 1, 4, 8, or 24 hours were harvested and subjected to semi-quantitative RT-PCR (A) and immunoblot analyses using antibodies against the SG or P-body components indicated; (B) β-actin served as a loading control.
Mentions: We next compared the expression levels of various SG and P-body components in M1-THPs and M2-THPs. We found no obvious differences in TIA1 or G3BP1 expression at either the transcriptional or protein level (Fig 4A and 4B), and the expression levels of these SG components were not affected by oxidative stress or by LPS stimulation. The levels of TTP, a zinc-finger-containing protein that promotes SG nucleation and the decay of AU-rich region (ARE)-containing mRNAs at P-bodies[32], increased in both M1-THPs and M2-THPs upon LPS stimulation. The most noticeable difference between M1-THPs and M2-THPs was in the expression levels of Dcp1a, an essential P-body component that also forms part of the decapping complex[22]. The Dcpla protein and mRNA levels were higher in M1-THPs than M2-THPs, and their expression in M1-THPs gradually increased during LPS stimulation (Fig 4A and 4B). This increase of Dcp1a in M1-THPs was consistent with the increased number of P-bodies in M1-THPs. When cells were treated with arsenite, a slow-migrating Dcp1a band was observed in both M1-THPs and M2-THPs (Fig 4B). This probably corresponded to a phosphorylated Dcp1a, since Dcp1a is known to undergo hyper-phosphorylation[41]. A slow-migrating band was not observed in LPS-treated cells. The protein level of Dcp2, a P-body component that catalyzes cytoplasmic mRNA decapping in conjunction with its coactivator Dcp1a[42], was similar in M1-THPs and M2-THPs.

Bottom Line: In contrast, P-body assembly in response to oxidative stress or TLR4 stimulation was increased in M1-THPs as compared to M2-THPs.These results suggest that mRNA metabolism is controlled differently in M1-THPs and M2-THPs.Interestingly, knocking down EDC4 or Dcp1a, which are components of P-bodies, severely reduced the production of IL-6, but not TNF-α in M1-THPs without decreasing the amount of IL-6 mRNA.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Immunology and Inflammation, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan; Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Gunma, Japan.

ABSTRACT
Macrophages play critical roles in the onset of various diseases and in maintaining homeostasis. There are several functional subsets, of which M1 and M2 macrophages are of particular interest because they are differentially involved in inflammation and its resolution. Here, we investigated the differences in regulatory mechanisms between M1- and M2-polarized macrophages by examining mRNA metabolic machineries such as stress granules (SGs) and processing bodies (P-bodies). Human monocytic leukemia THP-1 cells cultured under M1-polarizing conditions (M1-THPs) had less ability to assemble oxidative-stress-induced SGs than those cultured under M2-polarizing conditions (M2-THPs). In contrast, P-body assembly in response to oxidative stress or TLR4 stimulation was increased in M1-THPs as compared to M2-THPs. These results suggest that mRNA metabolism is controlled differently in M1-THPs and M2-THPs. Interestingly, knocking down EDC4 or Dcp1a, which are components of P-bodies, severely reduced the production of IL-6, but not TNF-α in M1-THPs without decreasing the amount of IL-6 mRNA. This is the first report to demonstrate that the assembly of EDC4 and Dcp1a into P-bodies is critical in the posttranscriptional regulation of IL-6. Thus, improving our understanding of the mechanisms governing mRNA metabolism by examining macrophage subtypes may lead to new therapeutic targets.

No MeSH data available.


Related in: MedlinePlus