D-011 | miR-191-5p regulates Neuronal Complexity and dendritic spine maturation during Mammalian Brain development

Cellular and Molecular Neurobiology
Author: Paula Macarena Gonzalez | Email: paugonzalez.0991@gmail.com

Paula M. Gonzalez^1°2°, Rodolfo Sanchez-Iazurlo^1°2°, David Alarcón Pastor^1°2°,  Paula A. Aguirre^1°2°, Sebastian A. Giusti^3°4°, Damian Refojo^3°4°, Fernando Bustos,  Juan Pablo Fededa^1°2°

^1° Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM) – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).
^2° Escuela de Bio y Nanotecnologías (EByN), Universidad Nacional de San Martín.
^3° Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)–CONICET–Partner Institute of the Max Planck Society, Buenos Aires, Argentina.
^4° Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany.

microRNA-191 (miR-191-5p), a small regulatory non-coding RNA, has been implicated as a marker of different neurodegenerative diseases, and is one of the major microRNA species expressed in the cerebral cortex from neurogenesis and throughout synaptogenesis.
To investigate the role of miR-191-5p during post-natal cortical development using loss of function experiments, we KO miR-191-5p in newborn mice using an adeno-associated virus (AAV) based CRISPR/Cas9 gene editing strategy to disrupt the structure of miR-191-5p precursor (pri-miR-191-5p) and suppress the generation of the mature microRNA.
Using Golgi-Cox staining combined with confocal microscopy to evaluate the morphology of cortical and hippocampal pyramidal neurons, we observed a reduction in the average length of neuronal processes and the total surface area of the dendritic tree in miR-191-5p KO mice vs. control. Similarly, in vitro miR-191-5p-depleted primary cultured neurons also exhibited shortened neuronal processes compared to control cultures.
We also analyzed the density and type of dendritic spines generated in miR-191-5p KO vs. control cultured neurons in vitro and found that miR-191-5p is necessary for the generation of mature spines.
Altogether, our data shows that miR-191-5p acts as a positive regulator of neuronal branching and connectivity during early post-natal brain development.