Generation and Characterization of Skeletal Muscle Cell based Model for GNE Myopathy: Implications in Actin Dynamics

Abstract UDP-N-acetyl glucosamine-2 epimerase/ N-acetyl mannosamine kinase (GNE) catalyzes key enzymatic reactions in the biosynthesis of sialic acid. Mutation in GNE gene causes GNE-Myopathy characterized by adult onset muscle weakness and degeneration. GNE is involved in different cellular processes like adhesion, apoptosis, ER stress and autophagy. Lack of appropriate model system limits drug and treatment options for GNE Myopathy as GNE knock out was found to be embryonically lethal. In the present study, we have generated L6 rat skeletal muscle cell-based model system for GNE Myopathy where GNE gene is knocked out at exon 3 using AAV mediated SEPT homology recombination. The cell line was heterozygous for GNE gene with one wild type and one truncated allele as confirmed by sequencing. The phenotype showed reduced GNE epimerase activity with little reduction in sialic acid content. In addition, the GNE knock out cell line revealed altered cytoskeletal organization with disrupted actin filament. The signaling cascade regulating actin dynamics such as Rho A, Cofilin, FAK and Src were altered leading to reduced cell migration in GNE heterozygous cells. Our study indicates possible role of GNE in regulating actin dynamics and cell migration of skeletal muscle cell. The skeletal muscle cell based system offers great potential in understanding pathomechanism and target identification for GNE Myopathy.