The matricellular protein Connective Tissue Growth Factor promotes motor axon regeneration

Regeneration of the neuromuscular junction (NMJ) is orchestrated by signals exchanged among its components. Neuronal hydrogen peroxide (H2O2), produced in response to injury, is a major Schwann cells (SC) activator. Genes differentially expressed by SCs exposed to H2O2 were used as a signature gene set for functional enrichment analysis of NMJ transcripts profiled during motor axon terminal degeneration and re-growth. We found that at the regenerating NMJ: i) the H2O2 signature is enriched in extracellular matrix terms; ii) the mRNA of Connective Tissue Growth Factor (Ctgf) is strongly up-regulated, iii) Ctgf is produced by terminal SCs, iv) Ctgf neutralization delays functional recovery upon nerve injury. We show here compelling evidence of a pro-regenerative role of Ctgf in neurotransmission rescue, and that the transcriptome of the regenerating NMJ is a powerful source of candidates with pro-regenerative potential. A profound ECM remodeling occurs during nerve regeneration, and H2O2 is among the triggers. Overall design: In this study, we performed RNA-Seq of neuromuscular junctions (NMJs) of soleus muscles from control and a-LTx treated mice (samples collected 4, 16, 72 and 168 hours after a-LTx injection) to investigate motor axon terminal degeneration and re-growth. Experiments were performed in biological triplicate (72h), quadruplicate (ctrl) and quintuplicate (4h, 16h, 168h).