A microRNA feedback loop regulates global microRNA abundance during aging

Area of Science:

• Molecular Biology
• Genetics
• Aging Research

Background:

• MicroRNA (miRNA) expression globally declines during organismal aging across taxa.
• The mechanisms and biological significance of age-related miRNA changes remain largely unknown.
• Investigating miRNA regulation in aging models like *C. elegans* is crucial.

Purpose of the Study:

• To elucidate the regulatory network controlling miRNA transcription and processing during *C. elegans* aging.
• To identify specific miRNAs and their targets involved in age-associated miRNA decline.
• To understand the functional consequences of altered miRNA biogenesis in aging.

Main Methods:

• Analysis of gene networks controlling miRNA biogenesis in aging *C. elegans*.
• Investigating the role of transcription factors and aging-associated miRNAs.
• Post-transcriptional repression analysis of *alg-1*/Argonaute by miR-71.

Main Results:

• miRNA biogenesis genes are intricately networked with transcription factors and aging miRNAs.
• miR-71, upregulated during aging, post-transcriptionally represses *alg-1*/Argonaute.
• Loss of *mir-71* function leads to increased ALG-1, global miRNA expression, mRNA dysregulation, and reduced lifespan variability.

Conclusions:

• Age-associated miRNA decline may be driven by miRNA-directed regulatory mechanisms, not solely accumulated damage.
• The miR-71/ALG-1 pathway significantly impacts miRNA expression levels and gene expression stability during aging.
• This study provides a novel miRNA-centric explanation for molecular decline and reduced lifespan variability in aging organisms.