The role of Smad2 in adult neuroplasticity as seen through hippocampal-dependent spatial learning/memory and neurogenesis

The role of Smad2 in adult neuroplasticity as seen through hippocampal-dependent spatial learning/memory and neurogenesis.

Adult neural plasticity is an important and intriguing phenomenon in the brain, and adult hippocampal neurogenesis is directly involved in modulating neural plasticity by mechanisms that are only partially understood. We have performed gain- and loss-of-function experiments to study Smad2, a transcription factor selected from genes that are demethylated after exercise through the analysis of an array of physical activity-induced factors, and its corresponding gene expression, and an efficient inducer of plasticity. In these studies, changes in cell number and morphology were analyzed in the hippocampal dentate gyrus (cell proliferation and survival -including regional distribution-, and structural maturation/differentiation -including arborization, dendritic spines and neurotransmitter-specific vesicles-) of sedentary male mice, after evaluation in a battery of behavioral tests. As a result, we reveal a role for Smad2 in the balance of proliferation vs. maturation of differentiating immature cells (Smad2 silencing increases both proliferation and survival of cycling cells in the dentate granule cell layer), and in the plasticity of both newborn and mature neurons in mice (by decreasing dendritic arborization and dendritic spine number). Moreover, Smad2 silencing specifically compromises spatial learning in mice (through impairments of spatial tasks acquisition both in long-term learning and working memory). These data suggest that Smad2 participates in adult neural plasticity by influencing the proliferation and maturation of dentate gyrus neurons.

Reference:

Simona Gradari, Antonio Herrera, Sebastián Pons, Patricia Tezanos, Jose Luis Trejo, Ángela Fontán-Lozano. Journal of Neuroscience

DOI: https://doi.org/10.1523/JNEUROSCI.2619-20.2021

The hippocampal dentate gyrus of an adult male mouse.