Depletion of SASH1, an astrocyte differentiation-related gene, contributes to functional recovery in spinal cord injury.

AIMS

This study aimed to evaluate the effects of the depletion of SAM and SH3 domain-containing protein 1 (SASH1) on functional recovery after spinal cord injury (SCI) and to investigate the possible mechanism of SASH1 knockdown in astrocytes facilitating axonal growth.

METHODS

SCI model was established in adult rats. SASH1 small interfering RNA (siSASH1) was used to investigate its function. Hindlimb motor function was evaluated by the Basso-Bresnahan-Beattie (BBB) assay. The gene expressions were evaluated by the methods of qRT-PCR, Western-blotting, ELISA, and immunohistochemistry.

RESULTS

SASH1 knockdown improved the BBB scores after SCI and significantly reduced GFAP expression. In cultured spinal astrocytes, siSASH1 treatment decreased interferon-γ release and increased brain-derived neurotrophic factor (BDNF) release. When cocultured with SASH1-knockdown astrocytes, axonal growth increased. The neuronal tropomyosin receptor kinase B (BDNF receptor) expression increased, especially in the axonal tips. SASH1 expression increased while NSCs differentiated into glial cells, instead of neurons. After SASH1 depletion, differentiated NSCs maintained a higher level of Nestin protein and an increase in BDNF release.

CONCLUSIONS

These results indicate that SASH1 acts as an astrocytic differentiation-maintaining protein, and SASH1 downregulation limits glial activation and contributes toward functional recovery after SCI.