Developmental regulation of RNA transcript destabilization by A + U-rich elements is AUF1-dependent

Area of Science:

• Immunology
• Molecular Biology
• Developmental Biology

Background:

• Neonatal immune cells exhibit functional immaturity compared to adult cells.
• Granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA stability is crucial for immune responses.
• The 3 -untranslated region (3 -UTR) containing an AU-rich element (ARE) regulates mRNA stability.

Purpose of the Study:

• To investigate the mechanisms underlying the decreased half-life of GM-CSF mRNA in neonatal mononuclear cells (MNC).
• To determine the role of the ARE and AUF1 protein in the accelerated turnover of GM-CSF mRNA in neonates.

Main Methods:

• Comparison of GM-CSF mRNA half-life in neonatal and adult MNC in vivo.
• In vitro decay assays of the GM-CSF 3 -UTR using protein fractions from neonatal and adult MNC.
• Analysis of decay intermediates and the effect of AUF1 immunodepletion.

Main Results:

• GM-CSF mRNA half-life is significantly shorter in neonatal (30 min) versus adult (100 min) MNC.
• The ARE in the GM-CSF 3 -UTR accelerates mRNA decay in vitro.
• Neonatal MNC protein accelerates 3 -UTR decay 4-fold more than adult MNC protein (19 min vs. 79 min).
• AUF1 depletion significantly attenuates the accelerated decay, confirming its role.

Conclusions:

• Developmental regulation of GM-CSF mRNA stability is mediated by accelerated ARE-dependent decay in neonatal MNC.
• The AU-rich element binding factor AUF1 plays a critical role in this accelerated turnover.
• These findings provide insights into the molecular basis of neonatal immune cell functional immaturity.