TENASCIN C REGULATES THE POPULATION OF IMMATURE NEURONS IN ADULT HIPPOCAMPUS THROUGH INTERACTION WITH ENRICHED ENVIRONMENT

Adult stem cell niches are specialized forms of extracellular matrix suitable for maintaining the development of newborn neurons. The process is regulated by internal and external factors, such as enriched environment (EE). The subgranular zone (SGZ) in the hippocampus is enriched with functional molecules such as tenascin C (TnC). The regulatory role of this glycoprotein is related to a variety of processes, from cell proliferation and migration to synaptic plasticity. However, the specific role of TnC in adult neurogenesis continues to be an area of ongoing investigation.
Hippocampal sections were immunostained for the proliferation marker Ki67 and for the marker of immature neurons doublecortin (DCX). Four experimental groups were used in the study - TnC+/+ mice housed in standard conditions, TnC+/+ mice in EE, TnC-/- mice in standard conditions, TnC-/- mice in EE. Laser scanning confocal microscopy was used to estimate the size of Ki67+ or DCX+ cellular populations in the SGZ. In addition, super-resolution Airyscan confocal microscopy enabled the investigation of the complexity of dendritic trees of DCX+ cells.
The results showed that TnC-deficiency does not alter either the size of Ki67+ and DCX+ cell populations, nor it affects the dendritic tree complexity of the developing neurons in the SGZ. However, reinforcement of adult neurogenesis by the exposure to EE leads to reduced number of DCX+ cells in TnC–deficient mice compared to wild type littermates.
These results suggest that by promoting adult neurogenesis with EE, additional regulatory pathways become activated, specifically the ones engaging TnC.