Dysregulation of GSK3β-Target Proteins in Skin Fibroblasts of Myotonic Dystrophy Type 1 (DM1) Patients

Article type: Research Article

Authors: Grande, Valentina^a | Hathazi, Denisa^{b; c} | O’Connor, Emily^d | Marteau, Theo^a | Schara-Schmidt, Ulrike^a | Hentschel, Andreas^b | Gourdon, Genevieve^e | Nikolenko, Nikoletta^f | Lochmüller, Hanns^{d; g; h; i} | Roos, Andreas^{a; d; *}

Affiliations: [a] Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany | [b] Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany | [c] Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK | [d] Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada | [e] Centre de Recherche en Myologie, Association Institut de Myologie, Sorbonne Université, Inserm UMR 974, Paris, France | [f] National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, UK | [g] Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON, Canada | [h] Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany | [i] Centro Nacional de AnálisisGenómico, Center for Genomic Regulation (CNAG-CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain

Correspondence: [*] Correspondence to: Andreas Roos, Tel.: +49 201 723 6570; E-mail: andreas.roos@uk-essen.de.

Abstract: Myotonic dystrophy type 1 (DM1) is the most common monogenetic muscular disorder of adulthood. This multisystemic disease is caused by CTG repeat expansion in the 3′-untranslated region of the DM1 protein kinase gene called DMPK. DMPK encodes a myosin kinase expressed in skeletal muscle cells and other cellular populations such as smooth muscle cells, neurons and fibroblasts. The resultant expanded (CUG)n RNA transcripts sequester RNA binding factors leading to ubiquitous and persistent splicing deregulation. The accumulation of mutant CUG repeats is linked to increased activity of glycogen synthase kinase 3 beta (GSK3β), a highly conserved and ubiquitous serine/threonine kinase with functions in pathways regulating inflammation, metabolism, oncogenesis, neurogenesis and myogenesis. As GSK3β-inhibition ameliorates defects in myogenesis, muscle strength and myotonia in a DM1 mouse model, this kinase represents a key player of DM1 pathobiochemistry and constitutes a promising therapeutic target. To better characterise DM1 patients, and monitor treatment responses, we aimed to define a set of robust disease and severity markers linked to GSK3βby unbiased proteomic profiling utilizing fibroblasts derived from DM1 patients with low (80– 150) and high (2600– 3600) CTG-repeats. Apart from GSK3β increase, we identified dysregulation of nine proteins (CAPN1, CTNNB1, CTPS1, DNMT1, HDAC2, HNRNPH3, MAP2K2, NR3C1, VDAC2) modulated by GSK3β. In silico-based expression studies confirmed expression in neuronal and skeletal muscle cells and revealed a relatively elevated abundance in fibroblasts. The potential impact of each marker in the myopathology of DM1 is discussed based on respective function to inform potential uses as severity markers or for monitoring GSK3β inhibitor treatment responses.

Keywords: GSK3β , fibroblast proteomics, CTPS1, CAPN1, HDAC2, CTNNB1

DOI: 10.3233/JND-200558

Journal: Journal of Neuromuscular Diseases, vol. 8, no. 4, pp. 603-619, 2021