Enhancing NeuroD1 Expression to Convert Lineage-Traced Astrocytes into Neurons

Xu, L.; Xiang, Z.-Q.; Guo, Y.-W.; Xu, Y.-G.; Liu, M.-H.; Ji, W.-Y.; He, S.; Lei, W.-L.; Li, W.; Wu, Z.; Chen, G.

doi:10.1101/2022.06.21.496971

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bioRxiv · 10.1101/2022.06.21.496971

Enhancing NeuroD1 Expression to Convert Lineage-Traced Astrocytes into Neurons

Xu, L.·Xiang, Z.-Q.·Guo, Y.-W.·Xu, Y.-G.·Liu, M.-H.·Ji, W.-Y.·He, S.·Lei, W.-L.·Li, W.·Wu, Z.·Chen, G.

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Abstract

Regenerating functional new neurons in adult mammalian brains has been proven a difficult task for decades. Recent advancement in direct glia-to-neuron conversion in vivo opens a new field for neural regeneration and repair. However, this emerging new field is facing serious challenges from misuse of viral vectors to misinterpretation of conversion data. Here, we employ a variety of AAV vectors with different promoters and enhancers to demonstrate that astrocytes can be converted into neurons in a NeuroD1 dose-dependent manner in both wildtype (WT) and transgenic mice. Notably, astrocytes in WT mice were relatively easy to convert with higher conversion efficiency, whereas lineage-traced astrocytes in Aldh1l1-CreERT2 mice showed high resistance to reprogramming but were still converted into neurons after enhancing NeuroD1 expression with CMV enhancer. Furthermore, under two-photon microscope, we observed direct astrocyte-to-neuron conversion within 3 weeks of serial live imaging in the mouse cortex. We also demonstrated that high titre AAV reaching 1013 GC/ml caused severe neuronal leakage using a variety of AAV GFAP::GFP vectors, highlighting the necessity to inject low titre AAV into healthy brains to avoid artifactual results. Together, our studies suggest that lineage-traced astrocytes can be converted into neurons but require stronger conversion force such as enhanced NeuroD1 expression. Failure to recognize the difference between WT astrocytes and lineage-traced astrocytes in terms of conversion barrier will lead to misinterpretation of data.

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Xu, L., Xiang, Z.-Q., Guo, Y.-W., Xu, Y.-G., Liu, M.-H., Ji, W.-Y., He, S., Lei, W.-L., Li, W., Wu, Z., Chen, G.. 2022-06-24. Enhancing NeuroD1 Expression to Convert Lineage-Traced Astrocytes into Neurons. https://doi.org/10.1101/2022.06.21.496971

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