Application of Antibodies to Neuronally Expressed Nogo-A Increases Neuronal Survival and Neurite Outgrowth

• Main Authors: Vini Nagaraj, Thomas Theis, Anmol Singh Johal, Arihant Seth, Jada Gore, Neha Arsha, Mukti Patel, Helen Baixia Hao, Nikki Kurian, Melitta Schachner
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: International Journal of Molecular Sciences
• Subjects: Nogo-A; antibody; neurite outgrowth; cell culture; mouse; signal transduction
• Online Access: https://www.mdpi.com/1422-0067/21/15/5417

Nogo-A, a glycoprotein expressed in oligodendrocytes and central nervous system myelin, inhibits regeneration after injury. Antibodies against Nogo-A neutralize this inhibitory activity, improve locomotor recovery in spinal cord-injured adult mammals, and promote regrowth/sprouting/saving of damaged axons beyond the lesion site. Nogo-A is also expressed by neurons. Complete ablation of Nogo-A in all cell types expressing it has been found to lead to recovery in some studies but not in others. Neuronal ablation of Nogo-A reduces axonal regrowth after injury. In view of these findings, we hypothesized that, in addition to neutralizing Nogo-A in oligodendrocytes and myelin, Nogo-A antibodies may act directly on neuronal Nogo-A to trigger neurite outgrowth and neuronal survival. Here, we show that polyclonal and monoclonal antibodies against Nogo-A enhance neurite growth and survival of cultured cerebellar granule neurons and increase expression of the neurite outgrowth-promoting L1 cell adhesion molecule and polysialic acid. Application of inhibitors of signal transducing molecules, such as c-src, c-fyn, protein kinase A, and casein kinase II reduce antibody-triggered neurite outgrowth. These observations indicate that the recovery-promoting functions of antibodies against Nogo-A may not only be due to neutralizing Nogo-A in oligodendrocytes and myelin, but also to their interactions with Nogo-A on neurons.