PDK1 coordinates mitochondrial dynamics and mitophagy to ensure mitochondrial maturation in post-natal cardiomyocytes

During early post-natal stage, cardiomyocytes undergo dramatic structural, metabolic, electrophysiological and cell cycle alterations towards maturation. Among them, the metabolic shift from carbohydrates to fatty acids metabolism is achieved along with mitochondrial biogenesis, dynamic switch and mitophagy. However, the regulatory mechanisms responsible for coordinated mitochondrial dynamics and mitophagy in mitochondrial maturation remain unclear. Here, we found that ablation of PDK1 in post-natal cardiomyocytes impairs mitochondrial maturation and metabolism, characterizing by arrest of mitochondria in neonatal stage, low levels of a subset of fatty acids and acylcarnitines. In addition, loss of PDK1 results in dysregulated mitochondrial dynamics and mitophagy. An imbalance of the AMPK-mTOR pathway and reduced phosphorylation of PDK1 substrates, including PKA and PKC family members, are observed. These results demonstrated that PDK1 ensures mitochondrial maturation and metabolic shift through kinase-dependent substrate phosphorylation and maintenance of the AMPK-mTOR axis to coordinate mitochondrial dynamics and mitophagy. Overall design: We then performed gene expression profiling analysis using data obtained from RNA-seq of wild type mouse heart at P0, P7 and P21, and PDK1 cKO hearts at P7 and P21.