Germline AGO2 mutations impair RNA interference and human neurological development.

Area of Science:

• Molecular Biology
• Genetics
• Neuroscience

Background:

• The RNA-induced silencing complex (RISC), comprising ARGONAUTE-2 (AGO2) and microRNAs (miRNAs), is critical for RNA interference, regulating gene expression through mRNA silencing and degradation.
• The specific roles of RISC components, particularly AGO2, in human development and organ function remain largely uncharacterized.

Purpose of the Study:

• To investigate the impact of ARGONAUTE-2 (AGO2) mutations on human neurological development.
• To elucidate the functional consequences of AGO2 variants within the RNA interference pathway.

Main Methods:

• Genetic analysis to identify mutations in the AGO2 gene in patients with neurological development disturbances.
• Functional assays to assess the effect of identified AGO2 mutations on short hairpin RNA (shRNA)-mediated gene silencing.
• Biochemical and cellular analyses to evaluate RISC complex formation, AGO2-mRNA binding, and phosphorylation status.
• Analysis of neuronal P-bodies and transcriptome alterations in patient-derived fibroblasts.

Main Results:

• Thirteen heterozygous mutations in AGO2 were identified in 21 patients with neurological development issues.
• All identified AGO2 mutations led to impaired shRNA-mediated gene silencing.
• Functional consequences included either defective RISC formation or enhanced AGO2 binding to mRNA targets.
• Impaired mRNA target release due to decreased phosphorylation of a C-terminal serine cluster was observed.
• Increased dendritic P-bodies in neurons and global transcriptome changes in patient fibroblasts were noted.

Conclusions:

• Genetic variations in AGO2 are associated with human neurological development disturbances.
• AGO2 mutations disrupt RNA interference by affecting RISC function and mRNA target interaction dynamics.
• Dynamic AGO2-RNA association is essential for proper human neuronal development, underscoring the importance of precise gene expression regulation.