Histone deacetylase isoforms regulate innate immune responses by deacetylating mitogen-activated protein kinase...

Area of Science:

• Immunology
• Molecular Biology
• Cellular Signaling

Background:

• Mitogen-activated protein kinase (MAPK) pathway is crucial for innate immune responses via Toll-like receptor (TLR) signaling.
• MKP-1 acetylation enhances its interaction with MAPK substrates, leading to TLR signaling deactivation.

Purpose of the Study:

• To investigate the role of Histone Deacetylases (HDACs) in regulating LPS-induced inflammation by examining their effect on MKP-1 deacetylation.
• To identify specific HDAC isoforms involved in this process and their impact on MAPK signaling.

Main Methods:

• Utilized mouse macrophages to assess the interaction between HDAC isoforms (HDAC1, -2, -3) and MKP-1.
• Employed genetic silencing and pharmacologic inhibition of HDACs to study MKP-1 acetylation and p38 MAPK phosphorylation.
• Investigated the effect of HDAC inhibition on LPS-induced inflammatory gene expression (TNF-α, IL-1β, iNOS) and nitrite synthesis in both wild-type and MKP-1 null cells.

Main Results:

• HDAC1, HDAC2, and HDAC3 were found to interact with MKP-1 in mouse macrophages.
• Inhibition of HDAC1, -2, and -3 led to increased MKP-1 acetylation and decreased LPS-induced p38 MAPK phosphorylation.
• Pharmacologic inhibition of HDACs did not affect MAPK signaling in MKP-1 null cells, confirming MKP-1's role.
• Inhibition of HDAC1, -2, and -3 significantly reduced LPS-induced expression of TNF-α, IL-1β, iNOS, and nitrite synthesis.

Conclusions:

• HDAC1, -2, and -3 deacetylate MKP-1, a post-translational modification that enhances MAPK and innate immune signaling.
• HDAC1, -2, and -3 isoforms represent potential therapeutic targets for managing inflammatory diseases.