MicroRNAs mediate precise control of spinal interneuron populations to exert delicate sensory-to-motor outputs

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• MicroRNA (miRNA) functions are well-studied in embryonic development but less understood postnatally.
• Redundant miRNA paralogs complicate functional studies, especially in neural circuits requiring behavioral assessment.
• The MiR34/449 family exhibits dynamic spinal cord expression from embryonic to postnatal stages.

Purpose of the Study:

• To investigate the postnatal neural functions of the MiR34/449 miRNA family in the spinal cord.
• To elucidate the role of MiR34/449 in sensory-to-motor circuit refinement and associated behaviors.

Main Methods:

• Utilized behavioral assays in mice to assess functions upon loss of MiR34/449.
• Conducted mechanistic studies to identify direct targets of MiR34/449.
• Analyzed the impact on specific neuronal populations, including motor synergy encoder (MSE) neurons.

Main Results:

• Loss of MiR34/449 miRNAs significantly altered thermally induced pain response thresholds.
• Complete loss of MiR34/449 function compromised delicate motor output.
• MiR34/449 were found to directly target Satb1 and Satb2, regulating the number of Satb1/2-expressing interneurons.

Conclusions:

• MiR34/449 miRNAs play a critical role in the postnatal development and function of spinal cord circuits.
• These miRNAs fine-tune the development of Satb1/2-expressing interneurons, essential for precise sensory-to-motor transformations.
• Understanding MiR34/449 function offers insights into neural circuit regulation and potential therapeutic targets for sensory-motor disorders.