Motor neuron loss in SMA is not associated with somal stress-activated JNK/c-Jun signaling

Celeste M. Pilato, Jae Hong Park, Lingling Kong, Constantin Van Outryve D'Ydewalle, David Valdivia, Karen S. Chen, Irene Griswold-Prenner, Charlotte J. Sumner

Research output: Contribution to journalArticle

Abstract

A pathological hallmark of spinal muscular atrophy (SMA) is severe motor neuron (MN) loss, which results in muscle weakness and often infantile or childhood mortality. Although it is well established that deficient expression of survival motor neuron (SMN) protein causes SMA, the molecular pathways that execute MN cell death are poorly defined. The c-Jun NH2-terminal kinases (JNKs) are stress-activated kinases with multiple substrates including c-Jun, which can be activated during neuronal injury and neurodegenerative disease leading to neuronal apoptosis. Recently, increased JNK-c-Jun signaling was reported in SMA raising the possibility that JNK inhibitors could be a novel treatment for this disease. We examined JNK-c-Jun activity in SMA mouse and human cultured cells and tissues. Anisomycin treatment of human SMA fibroblasts and sciatic nerve ligation in SMA mice provoked robust phosphorylated-c-Jun (p-c-Jun) expression indicating that SMN-deficiency does not prevent activation of the stress-induced JNK-c-Jun signaling pathway. Despite retained capacity to activate JNK-c-Jun, we observed no basal increase of p-c-Jun levels in SMA compared to control cultured cells, human or mouse spinal cord tissues, or mouse MNs during the period of MN loss in severe SMA model mice. In both controls and SMA, ~50% of α-MN nuclei express p-c-Jun with decreasing expression during the early postnatal period. Together these studies reveal no evidence of stress-activated JNK-c-Jun signaling in MNs of SMA mice or human tissues, but do highlight the important role of JNK-c-Jun activity during normal MN development raising caution about JNK antagonism in this pediatric neuromuscular disease.

Original languageEnglish (US)
Pages (from-to)3282-3292
Number of pages11
JournalHuman molecular genetics
Volume28
Issue number19
DOIs
StatePublished - Oct 1 2019

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Genetics(clinical)

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    Pilato, C. M., Park, J. H., Kong, L., Van Outryve D'Ydewalle, C., Valdivia, D., Chen, K. S., Griswold-Prenner, I., & Sumner, C. J. (2019). Motor neuron loss in SMA is not associated with somal stress-activated JNK/c-Jun signaling. Human molecular genetics, 28(19), 3282-3292. https://doi.org/10.1093/hmg/ddz150