Smg5 Enhances Oligodendrocyte Differentiation via Nonsense-Mediated mRNA Decay of Hnrnpl Variant Transcripts

Area of Science:

• Neuroscience
• Molecular Biology
• RNA Biology

Background:

• Nonsense-mediated mRNA decay (NMD) is a vital RNA surveillance pathway.
• NMD degrades transcripts with premature termination codons (PTCs) and regulates gene expression.
• Oligodendrocytes are crucial for central nervous system (CNS) myelination.

Purpose of the Study:

• To investigate the role of SMG5-mediated NMD in oligodendrocyte development and CNS myelination.
• To determine the impact of disrupting NMD on oligodendrocyte differentiation and myelin gene expression.

Main Methods:

• Conditional knockout of the NMD factor Smg5 in oligodendrocyte lineage cells of mice.
• Analysis of RNA transcripts, oligodendrocyte differentiation markers, and myelin gene expression.
• Assessment of myelin sheath thickness and motor function in knockout mice.

Main Results:

• Conditional Smg5 knockout disrupted the degradation of PTC-containing transcripts, including Hnrnpl variants.
• Loss of SMG5 impaired oligodendrocyte differentiation and reduced myelin gene expression in both male and female mice.
• Mice with Smg5 loss exhibited thinner myelin sheaths and compromised motor function.
• HNRNPL was identified as a regulator of alternative splicing for myelin genes Mag and Nfasc, promoting oligodendrocyte differentiation.

Conclusions:

• SMG5-mediated NMD is essential for RNA processing fidelity during oligodendrocyte development.
• Disruption of NMD by Smg5 loss leads to impaired myelination and neurological deficits.
• These findings highlight the critical role of NMD in maintaining CNS integrity and function.