A CREB2-targeting microRNA is required for long-term memory after single-trial learning

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Single-trial learning's mechanism for long-term memory (LTM) formation is poorly understood.
• MicroRNAs (miRNAs) are implicated in regulating gene expression and synaptic plasticity.
• Investigating molecular mechanisms underlying memory consolidation is crucial.

Purpose of the Study:

• To elucidate the role of miRNAs in single-trial induced LTM.
• To identify specific miRNAs involved in memory formation after a single learning event.
• To explore the regulatory relationship between miRNAs and memory-associated genes.

Main Methods:

• Construction and next-generation sequencing of small non-coding RNA (sncRNA) cDNA libraries from Lymnaea stagnalis.
• Identification of training-regulated miRNAs, focusing on Lym-miR-137.
• Analysis of Lym-miR-137 and Lym-CREB2 mRNA co-expression in identified neurons.
• In vivo loss-of-function experiments to assess Lym-miR-137's necessity for LTM.

Main Results:

• Training induced a specific pool of miRNAs, including Lym-miR-137.
• Lym-miR-137 targets the 3' UTR of Lym-CREB2 mRNA, a known memory repressor.
• Lym-miR-137 was upregulated post-conditioning, preceding Lym-CREB2 mRNA downregulation.
• Lym-miR-137 is essential for single-trial induced LTM in Lymnaea stagnalis.

Conclusions:

• MicroRNA-mediated repression of molecular inhibitory constraints is vital for LTM formation after single-trial learning.
• Lym-miR-137 plays a critical role in facilitating LTM by downregulating memory repressors like Lym-CREB2.
• This study reveals a novel molecular pathway for memory consolidation.