Common and Key Differential Pathogenic Pathways in Desminopathy and Titinopathy

Myofibrillar myopathy (MFM) is a group of hereditary myopathies that mainly involves striated muscles. This study aimed to use tandem mass tag (TMT)-based proteomics to investigate the underlying pathomechanisms of two of the most common MFM subtypes, desminopathy and titinopathy. Muscles from 7 patients with desminopathy, 5 with titinopathy and 5 control individuals were included. Samples were labelled with TMT and then underwent high-resolution liquid chromatography-mass spectrometry analysis. Compared with control samples, there were 436 differentially abundant proteins (DAPs) in the desminopathy group and 269 in the titinopathy group. When comparing the desminopathy with the titinopathy group, there were 113 DAPs. In desminopathy, mitochondrial ATP production, muscle contraction, and cytoskeleton organization were significantly suppressed. Activated cellular components and pathways were mostly related to extracellular matrix (ECM). In titinopathy, mitochondrial-related pathways and the cellular component ECM were downregulated, while gluconeogenesis was activated. Direct comparison between desminopathy and titinopathy revealed hub genes that were all involved in glycolytic process. The disparity in glycolysis in the two MFM subtypes is likely due to fiber type switching. This study has revealed disorganization of cytoskeleton and mitochondrial dysfunction as the common pathophysiological processes in MFM, and glycolysis and ECM as the differential pathomechanism between desminopathy and titinopathy. This offers a future direction for targeted therapy for MFM.