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Myotonic dystrophy type 1 (DM1; MIM #160900) is an autosomal dominant disorder, clinically characterized by progressive muscular weakness and multisystem degeneration. The broad phenotypes observed in patients with DM1 resemble the appearance of an accelerated aging process. However, the molecular mechanisms underlying these phenotypes remain largely unknown. Transcriptomic analysis of fibroblasts derived from patients with DM1 and healthy individuals revealed a decrease in cell cycle activity, cell division, and DNA damage response in DM1, all of which related to the accumulation of cellular senescence. The data from transcriptome analyses were corroborated in human myoblasts and blood samples, as well as in mouse and Drosophila models of the disease. Serial passage studies in vitro confirmed the accelerated increase in senescence and the acquisition of a senescence-associated secretory phenotype in DM1 fibroblasts, whereas the DM1 Drosophila model showed reduced longevity and impaired locomotor activity. Moreover, functional studies highlighted the impact of BMI1 and downstream p16INK4A/ RB and ARF/p53/p21CIP pathways in DM1-associated cellular phenotypes. Importantly, treatment with the senolytic compounds Quercetin, Dasatinib, or Navitoclax reversed the accelerated aging phenotypes in both DM1 fibroblasts in vitro and in Drosophila in vivo. Our results identify the accumulation of senescence as part of DM1 pathophysiology and, therefore, demonstrate the efficacy of senolytic compounds in the preclinical setting. MGP and ASA are recipient of predoctoral fellowships from the University of the Basque Country (PIF 15/245) and Carlos III Institute (FI17/00250), respectively. We thank the methodological support service of Biodonostia Institute for help with statistical analysis. This work is supported by grants from the Instituto Salud Carlos III and FEDER funds (PI16/01580, PI17/01841, DTS18/00181, PI19/01355, CPII19/00021, and DTS20/00179), La Caixa, and Health department from Basque Country (2017222021, 2018222021, and 2020333008).

[EUS] Lan honen bidez lortu nahi den helburu nagusia LiCl bidezko tratamenduak TDP-43 proteinaren kontzentrazioa zein lokalizazio zelularra aldatzen duen finkatzea da. Halaber, ikerketa honen bidez lortu nahi diren gainerako helburuak ondokoak dira: • Litioa bezala, GSK3βren inhibitzaileak diren Tideglusib eta VPO.7 bidezko tratamenduek TDP43aren lokalizazio zelularrean eraginik duten behatzea. • Erabilitako farmakoek, Wnt bidezidorraren bidez β-kateninarengan eragiten dutenez, TPD-43rekiko efektua β-kateninarekiko menpekoa ote den azaltzea. Azkenik, litio, Tideglusib eta VP0.7 farmakoek muskulu distrofietan agertzen den TDP-43 miogranulu zitoplasmatikoen kontzentrazio patologikoaren murrizketa lortuko balute, farmako hauek distrofia muskularren tratamendurako proposatuak izango lirateke. [ES] El objetivo principal que se persigue con este trabajo es determinar qué localización celular de la proteína TDP-43 es debida al tratamiento con LiCl. Asimismo, el resto de objetivos que se persiguen con esta investigación son: • Observar si, al igual que el litio, los tratamientos mediante Tideglusib y VPO.7, inhibidores del GSK3ß, afectan a la localización celular del TDP43. • Explicar si el efecto sobre el TPD-43, al incidir los fármacos utilizados en la senda Wnt sobre la ßkatenina, depende de la misma. Por último, si los fármacos Litio, Tidegclub y VP0.7 obtuvieran una reducción de la concentración patológica de los miogránulos citoplasmáticos TDP-43 presentes en las distrofias musculares, éstos serían propuestos para el tratamiento de las distrofias musculares.