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Heat shock protein 60 negatively regulates the biological functions of ubiquitin-like protein MNSFβ in macrophages

Morihiko Nakamura1, Kaori Notsu2, Mai Nakagawa2

  • 1Division of Regional Collaborative Medical Research, Office for Regional Collaboration and Innovation, Shimane University, Izumo, 693-8501, Japan. nkmr0515@med.shimane-u.ac.jp.

Molecular and Cellular Biochemistry
|February 3, 2019
PubMed

Insights

Monoclonal nonspecific suppressor factor β (MNSFβ), a ubiquitin-like protein, conjugates with heat shock protein 60 (HSP60). This interaction reveals HSP60 as a molecular chaperone that negatively regulates MNSFβ activity, impacting apoptosis and TNFα production.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Immunology

Background:

  • Monoclonal nonspecific suppressor factor β (MNSFβ) is a ubiquitin-like protein with diverse biological roles.
  • MNSFβ is known to modify target proteins, including the proapoptotic protein Bcl-G.

Purpose of the Study:

  • To identify and characterize MNSFβ adducts in mouse liver lysates.
  • To investigate the role of molecular chaperones in regulating MNSFβ activity.

Main Methods:

  • Purification of MNSFβ adducts using sequential chromatography and GST-fusion protein immobilization.
  • Identification of adduct components via MALDI-TOF mass spectrometry.
  • Functional analysis using siRNA to deplete HSP60 in LPS/IFNγ-stimulated Raw264.7 cells.

Main Results:

  • A 65 kDa MNSFβ adduct was purified, consisting of MNSFβ and heat shock protein 60 (HSP60).
  • Mass spectrometry confirmed MNSFβ conjugation to HSP60 at specific residues (Gly74 and Lys481).
  • HSP60 depletion reversed MNSFβ siRNA-mediated inhibition of apoptosis and TNFα production in macrophages.

Conclusions:

  • MNSFβ activity is negatively regulated by the molecular chaperone HSP60.
  • This study provides the first evidence of MNSFβ regulation by a molecular chaperone.
  • The findings elucidate a novel mechanism controlling MNSFβ function in immune cells.
Keywords:
Inflammation responsesMolecular chaperoneUbiquitin-like protein

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