Upregulation of Hallmark Muscle Genes Protects Gne(M743T/M743T) Mutated Knock-In Mice From Kidney and Muscle Phenotype

BACKGROUND: Mutations in GNE cause a recessive, adult onset myopathy characterized by slowly progressive distal and proximal muscle weakness. Knock-in mice carrying the most frequent mutation in GNE myopathy patients, Gne(M743T/M743T), usually die few days after birth from severe renal failure, with no muscle phenotype. However, a spontaneous sub-colony remains healthy throughout a normal lifespan without any kidney or muscle pathology. OBJECTIVE: We attempted to decipher the molecular mechanisms behind these phenotypic differences and to determine the mechanisms preventing the kidney and muscles from disease. METHODS: We analyzed the transcriptome and proteome of kidneys and muscles of sick and healthy Gne(M743T/M743T) mice. RESULTS: The sick Gne(M743T/M743T) kidney was characterized by up-regulation of extra-cellular matrix degradation related processes and by down-regulation of oxidative phosphorylation and respiratory electron chain pathway, that was also observed in the asymptomatic muscles. Surprisingly, the healthy kidneys of the Gne(M743T/M743T) mice were characterized by up-regulation of hallmark muscle genes. In addition the asymptomatic muscles of the sick Gne(M743T/M743T) mice showed upregulation of transcription and translation processes. CONCLUSIONS: Overexpression of muscle physiology genes in healthy Gne(M743T/M743T) mice seems to define the protecting mechanism in these mice. Furthermore, the strong involvement of muscle related genes in kidney may bridge the apparent phenotypic gap between GNE myopathy and the knock-in Gne(M743T/M743T) mouse model and provide new directions in the study of GNE function in health and disease.