Probing regenerative heterogeneity of corticospinal neurons with scRNA-Seq

Not specified, 2023 · DOI: https://doi.org/10.21203/rs.3.rs-2588274/v1 · Published: February 21, 2023

Neurology Bioinformatics Regenerative Medicine & Stem Cells

Simple Explanation

This study investigates why only some corticospinal tract (CST) axons regenerate after spinal cord injury, even with molecular interventions. They used single-cell RNA sequencing (scRNA-Seq) to deeply analyze the gene expression of individual regenerating neurons. The researchers identified key transcriptomic signatures, including antioxidant response and mitochondrial biogenesis, associated with regenerative ability. They found that NFE2L2, a regulator of antioxidant response, plays a critical role in CST regeneration. The study developed a 'Regenerating Classifier' (RC) to assess the regenerative ability of different neuron types based on their gene expression profiles. The RC showed that embryonic neurons are more likely to regenerate than adult neurons and that neurons can revert to a regenerative state after injury.

Study Duration

10 weeks post-injury survival time

Participants

326 CST neurons (123 regenerating, 203 non-regenerating) from 29 PTENfl/fl;SOCS3fl/fl;tdTomatofl/fl mice

Evidence Level

Not specified

Key Findings

1
Mitochondrial activities are heavily involved in CST regeneration, with genes related to ATP metabolism and oxidative phosphorylation being overexpressed in regenerating neurons.
2
NFE2L2 (NRF2), a master regulator of the antioxidant defense system, is a positive regulator of CST regeneration, as its deletion diminishes regeneration induced by PTEN deletion.
3
A 'Regenerating Classifier' (RC) can predict the regenerative potential of different neuronal populations based on their transcriptomic profiles, reflecting developmental stage and injury status.

Research Summary

This study uses patch-based single-cell RNA sequencing to investigate the transcriptomic profiles of regenerating versus non-regenerating corticospinal tract (CST) neurons following PTEN and SOCS3 deletion. The study identifies new candidates for regeneration regulators, validates NFE2L2 as a positive regulator of CST regeneration, and develops a Regeneration Classifier that exhibits predictive value for the regenerative abilities of various neuronal types. The findings suggest the existence of universal transcriptomic features underlying the regenerative abilities of different neuronal populations and highlight the value of deep sequencing on a relatively small number of neurons in studying CNS axon regeneration.

Practical Implications

Therapeutic Target Identification

NFE2L2 (NRF2) and related antioxidant pathways may represent novel therapeutic targets for promoting CST regeneration after spinal cord injury.

Personalized Regenerative Medicine

The Regenerating Classifier (RC) could be used to assess the regenerative potential of individual patients' neurons and tailor regenerative therapies accordingly.

Understanding Developmental Constraints

The RC's ability to reflect developmental stage suggests that understanding the mechanisms underlying the decline in regenerative potential with age could lead to strategies for rejuvenating adult neurons' regenerative capacity.

Study Limitations

1
The study focuses on CST regeneration following PTEN and SOCS3 deletion, which may not fully represent the regenerative response to other types of injury or molecular interventions.
2
The relatively low sample size, despite the high sequencing depth, may limit the ability to capture all transcriptomic features associated with regeneration.
3
The study acknowledges that the Regenerative Classifier requires further refinement to reduce noise and improve its predictive power.

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