Mitochondrial dysfunction triggers a pro-survival adaptive response through distinct DNA methylation of nuclear genes.

GARCIA SANMARTINO, CLARA; ROMANO, PATRICIA SILVIA; SALASSA, BETIANA NEBAÍ; EIROA, HERNAN; MAYORGA, LIA; LOOS, MARIANA A.; ROQUE MORENO, MARIA

Mendoza

Congreso; 23th International Annual Congress of the World Muscle Society; 2018

WMS

Background: Epigenetics can modulate cellular responses to stress and DNA methylation has been associated to high intensity stress adaptive responses. We hypothesized that MT dysfunction could trigger an epigenetically mediated adaptive response. To test this, we studied stress responses in an in vitro and in vivo model of MT dysfunction and explored their epigenetic modulation.Results: In vitro: human skeletal myoblasts exposed to the MT complex I inhibitor Rotenone (Rot) showed that low doses (Rot-0.1M) enhanced cell death through apoptosis whereas higher doses (Rot-1/10M) maintained apoptosis to the control level (Annexin V flow cytometry). Autophagy was increased in the Rot-10M condition (LC3 IIF+WB) and we proved that it was necessary for the cells to survive. DNA methylation inhibition with 5-Aza-2′-deoxycytidine (5-Aza) evidenced that methylation was also necessary for this ?pro-survival? state since cells showed enhanced apoptosis and inhibition of autophagy when treated with Rot-10M+5-Aza. In vivo: Skeletal muscle and blood samples were obtained from MT disease patients and controls. Autophagy was explored in muscle samples with LC3 WB revealing increased autophagy in patients. DNA methylation assays of tumor suppressor genes (MS-MLPA) was enhanced in both of patient?s tissues. Reduced representative bisulfite sequencing (RRBS) also evidenced hypermethylation of CpG rich regions in patients? muscles. With G.R.E.A.T analysis of the RRBS data, we found that the pathways altered by distinct methylation correlated with the ones known to be dysregulated at a transcriptional level. Therefore, the transcriptome could be driven by DNA methylation in this MT dysfunctional scenario. We highlight the alteration in methylation and transcription of the ?Nutrient sensing network? important for autophagy regulation. Conclusion: MT dysfunction unshackles a ?pro-survival? response that seems to be triggered by the differential methylation of nuclear genes.