Regulation of ubiquitin-proteasome and autophagy pathways after acute LPS and epoxomicin administration in mice

Cécile Jamart, Aldrin V Gomes, Shannamar Dewey, Louise Deldicque, Jean Marc Raymackers, Marc Francaux

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The ubiquitin-proteasome pathway (UPP) is a major protein degradation pathway that is activated during sepsis and has been proposed as a therapeutic target for preventing skeletal muscle loss due to cachexia. Although several studies have investigated the modulation of proteasome activity in response to LPS administration, none have characterized the overall UPP response to LPS administration in the fate of proteasome inhibition. Methods. Here, we determined the modulation pattern of the main key components of the UPP in the gastrocnemius (GAS) of mice during the acute phase of lipopolysaccharide (LPS)-mediated endotoxemia (7.5 mg/kg - 8 h) by measuring all three β1, β2 and β5 activites of the 20S and 26S proteasomes, the levels of steady state polyubiquitinated proteins, mRNA levels of muscle ligases, as well as signaling pathways regulating the UPP. Another goal was to assess the effects of administration of a specific proteasome inhibitor (epoxomicin, 0.5 mg/kg) on UPP response to sepsis. Results: The acute phase of LPS-induced endotoxemia lowered GAS/body weight ratio and increased MuRF1 and MAFbx mRNA concomitantly to an activation of the pathways known to regulate their expression. Unexpectedly, we observed a decrease in all 20S and 26S proteasome activities measured in GAS, which might be related to oxidative stress, as oxidized proteins (carbonyl levels) increase with LPS. While significantly inhibiting 20S and 26S proteasome β5 activities in heart and liver, epoxomicin did not lower proteasome activity in GAS. However, the increase in mRNA expression of the muscle ligases MuRF1 and MAFbx were partially rescued without affecting the other investigated signaling pathways. LPS also strongly activated autophagy, which could explain the observed GAS atrophy with LPS-induced reduction of proteasome activity. Conclusions: Our results highlight an opposite regulation of UPP in the early hours of LPS-induced muscle atrophy by showing reduced proteasome activities and increased mRNA expression of muscle specific ligases. Furthermore, our data do not support any preventive effect of epoxomicin in muscle atrophy due to acute cachexia since proteasome activities are not further repressed.

Original languageEnglish (US)
Article number166
JournalBMC Musculoskeletal Disorders
Volume15
Issue number1
DOIs
StatePublished - May 22 2014

Fingerprint

Autophagy
Proteasome Endopeptidase Complex
Ubiquitin
Lipopolysaccharides
Ligases
Messenger RNA
Cachexia
Endotoxemia
Muscular Atrophy
epoxomicin
Muscles
Sepsis
Proteasome Inhibitors
Proteolysis
Atrophy

Keywords

  • Endotoxemia
  • LC3
  • MAFbx
  • MuRF1
  • Proteasome inhibitors

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Rheumatology
  • Medicine(all)

Cite this

Regulation of ubiquitin-proteasome and autophagy pathways after acute LPS and epoxomicin administration in mice. / Jamart, Cécile; Gomes, Aldrin V; Dewey, Shannamar; Deldicque, Louise; Raymackers, Jean Marc; Francaux, Marc.

In: BMC Musculoskeletal Disorders, Vol. 15, No. 1, 166, 22.05.2014.

Research output: Contribution to journalArticle

Jamart, Cécile ; Gomes, Aldrin V ; Dewey, Shannamar ; Deldicque, Louise ; Raymackers, Jean Marc ; Francaux, Marc. / Regulation of ubiquitin-proteasome and autophagy pathways after acute LPS and epoxomicin administration in mice. In: BMC Musculoskeletal Disorders. 2014 ; Vol. 15, No. 1.
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AU - Raymackers, Jean Marc

AU - Francaux, Marc

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