Regulation of chemokine mRNA stability by lipopolysaccharide and IL-10

Area of Science:

• Immunology
• Molecular Biology
• Gene Regulation

Background:

• Interleukin-10 (IL-10) is known to suppress proinflammatory cytokine expression.
• The precise molecular mechanisms by which IL-10 modulates gene expression, particularly mRNA stability, remain largely unknown.
• Lipopolysaccharide (LPS) induces the expression of proinflammatory mediators, involving alterations in mRNA stability.

Purpose of the Study:

• To elucidate the molecular targets and mechanisms through which IL-10 influences LPS-induced mRNA stability.
• To investigate the role of mRNA decay pathways in the regulation of CXC ligand 1 (KC) mRNA by LPS and IL-10.
• To characterize the impact of LPS and IL-10 on the stability of KC mRNA in macrophages.

Main Methods:

• Utilized primary peritoneal exudate macrophages and a RAW264.7 cell culture model with a tetracycline-responsive promoter for KC mRNA.
• Employed a cell-free mRNA degradation system using in vitro transcribed KC mRNA with wild-type and mutated AU-rich elements (AREs).
• Analyzed mRNA decay rates and protein extract activities from cells treated with LPS and/or IL-10.

Main Results:

• LPS treatment led to a time-dependent increase in KC mRNA stability.
• IL-10 alone did not affect mRNA decay but antagonized the stabilizing effect of LPS on KC mRNA.
• Cell-free assays demonstrated that LPS reduced mRNA decay activity, an effect blunted by IL-10, particularly involving ARE-dependent and independent degradation pathways.

Conclusions:

• KC mRNA stability is regulated by LPS through modulation of deadenylation and mRNA body degradation activities.
• IL-10 counteracts the stabilizing effects of LPS on KC mRNA by antagonizing these LPS-induced changes.
• These findings provide insights into the molecular mechanisms of IL-10's anti-inflammatory actions at the post-transcriptional level.