HETEROPLASMY SHIFTING IN MICE TRANSMITOCHONDRIAL EMBRYONIC STEM CELLS DUE TO CULTIVATION IN LOW-GLUCOSE CONDITIONS

Most of the pathogenic mutations in human mitochondrial DNA are heteroplasmic and their phenotypic expression is intimately linked to the ratio between mutant mitochondrial DNA and wild-type one. Thus, modulating the heteroplasmy level appears as a potential therapeutic approach. Our team has developed an « anti-replicative » strategy, which consists in targeting mitochondria with recombinant RNAs containing sequences able to specifically anneal with the mutant mitochondrial DNA and interfere with its replication. This approach has first been assayed on cybrid cell lines (Comte et al., 2013). We also observed that cultivation of cybrid cell lines expressing recombinant RNAs in media with reduced concentration of glucose was accompanied by a more pronounced heteroplasmy shift. To develop another cell model, a mice transmitochondrial embryonic stem (ES) cell line harboring a point mutation m8414A>G in mt-atp6 has been created as described in (Kirby et al., 2009). Surprisingly, all the ES cells cultivated in low-glucose medium demonstrated a stable decrease of the heteroplasmy level from 95% to 60% of mutant mitochondrial DNA. This is a first example of such an important heteroplasmy shift obtained by a change of the cultivation conditions.