Mini-TrpRS is essential for IFNγ-induced monocyte-derived giant cell formation

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Aminoacyl-tRNA synthetases, including truncated tryptophanyl-tRNA synthetase (mini-TrpRS), are primarily known for their role in protein synthesis.
• Emerging evidence suggests non-canonical functions for these enzymes beyond translation.

Purpose of the Study:

• To investigate the potential signaling role of mini-TrpRS in monocyte differentiation into multinuclear giant cells (MGCs).
• To elucidate the mechanism by which Interferon-gamma (IFNγ) induces MGC formation, focusing on the involvement of mini-TrpRS.

Main Methods:

• Utilized small interfering RNA (siRNA) to target and inhibit mini-TrpRS expression in monocytes.
• Administered D-Tryptophan as a decoy substrate to block mini-TrpRS signaling.
• Assessed monocyte aggregation and MGC formation in response to IFNγ stimulation.
• Quantified the expression levels of the purinergic receptor P2X 7 (P2RX7) in treated monocytes.

Main Results:

• IFNγ stimulation induced significant monocyte aggregation and MGC formation, accompanied by increased mini-TrpRS expression.
• Inhibition of mini-TrpRS using siRNA or D-Tryptophan effectively prevented IFNγ-induced monocyte aggregation.
• Blockade of mini-TrpRS led to a marked reduction in P2RX7 expression in IFNγ-activated monocytes.

Conclusions:

• Mini-TrpRS plays a critical signaling role in IFNγ-mediated monocyte-derived giant cell formation.
• Mini-TrpRS signaling is involved in the regulation of P2RX7 expression during monocyte activation.
• These findings reveal a novel non-canonical function of mini-TrpRS in innate immune cell differentiation.