Gene expression profile of SOD1-G93A mouse spinal cord, blood and muscle

Abstract

The exact pathway leading to neuron death and muscle atrophy in amyotrophic lateral sclerosis (ALS) has not yet been elucidated. Gene expression profile of spinal cord, blood and muscle could provide signalling pathways and systemic alterations useful for future biomarker development. In our study we compared whole genome expression profiles of lumbar spinal cord with peripheral blood and tibialis anterior muscle in 16 mutant SOD1-G93A mice and 15 wild-type littermates. In SOD1-G93A mice, 11 genes were significantly differentially expressed in spinal cord, and 16 genes in blood, while much larger transcriptional changes were noted in muscle (1745 genes significant; six overlapping with spinal cord (0.3%)) probably due to muscle atrophy. Overlap with spinal cord was enriched for significant genes in blood (six of 16 overlapping with spinal cord (37.5%)). Three genes were significantly down-regulated in all three tissues, and were closely related to mitochondrial function. Furthermore, clustering the significant genes in spinal cord and in blood, but not in muscle, could identify the SOD1-G93A mice. We conclude that blood gene expression profile overlapped with profile of spinal cord, allowing differentiation of SOD1-G93A mice from wild-type littermates. Blood gene expression profiling may be a promising biomarker for ALS patients.

Key words::

• SOD1
• transgenic animals
• RNA
• biomarkers

Acknowledgements

We thank Henk Veldman, Ruben van‘t Slot and Peter Sodaar for technical assistance with experimental procedures and RNA preparation. This project has been generously supported by the European Community’s Health Seventh Framework Programme, Netherlands Organization for Health Research and Development, Prinses Beatrix Fonds, Netherlands ALS Foundation, VSB Fonds and Adessium Foundation. L. H. B received travel grants and consultancy fees from Baxter International, Prinses Beatrix Fonds and Biogen Idec; and serves on the editorial board of Amyotrophic Lateral Sclerosis.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.