MicroRNA-34a Modulates Neural Stem Cell Differentiation by Regulating Expression of Synaptic and Autophagic Proteins
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We have previously demonstrated the involvement of specific apoptosis-associated microRNAs (miRNAs), including miR-34a, in mouse neural stem cell (NSC) differentiation. In addition, a growing body of evidence points to a critical role for autophagy during neuronal differentiation, as a response-survival mechanism to limit oxidative stress and regulate synaptogenesis associated with this process. The aim of this study was to further investigate the precise role of miR-34a during NSC differentiation. Our results showed that miR-34a expression was markedly downregulated during neurogenesis. Neuronal differentiation and cell morphology, synapse function, and electrophysiological maturation were significantly impaired in miR-34a-overexpressing NSCs. In addition, synaptotagmin 1 (Syt1) and autophagy-related 9a (Atg9a) significantly increased during neurogenesis. Pharmacological inhibition of autophagy impaired both neuronal differentiation and cell morphology. Notably, we showed that Syt1 and Atg9a are miR-34a targets in neural differentiation context, markedly decreasing after miR-34a overexpression. Syt1 overexpression and rapamycin-induced autophagy partially rescued the impairment of neuronal differentiation by miR-34a. In conclusion, our results demonstrate a novel role for miR-34a regulation of NSC differentiation, where miR-34a downregulation and subsequent increase of Syt1 and Atg9a appear to be crucial for neurogenesis progression.
KeywordsAutophagy MicroRNA Neural stem cell Neurogenesis Synaptogenesis
- 3′ UTR
3′ Untranslated region
Basic fibroblast growth factor
Fetal bovine serum
Microtubule-associated protein light chain 3
Microtubule-associated protein 2
Neural stem cell
Quantitative reverse transcription polymerase chain reaction
We thank Dr. Massimiliano Agostini (Medical Research Council, Leicester University, Leicester, UK) for kindly providing Syt1 overexpression and Luc-Syt1 3′ UTR vectors. We also thank all members of the laboratory for the insightful discussions.
Conflict of Interest
The authors declare that they have no conflict of interest. This work was supported by grants PTDC/SAU-NMC/117877/2010 and PTDC/BIM-MED/0251/2012 and by fellowships SFRH/BD/80060/2011 (ALM) and SFRH/BD/68368/2010 (JMX) from Fundação para a Ciência e a Tecnologia, Lisbon, Portugal.
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