摘要
Hypertonia is a neurological dysfunction associated with a number of central nervous system disorders, including cerebral palsy, Parkinson＇s disease, dystonia, and epilepsy. Genetic studies have identified a homozygous truncation mutation in Trakl that causes hypertonia in mice. Moreover, elevated Trakl protein expression is associated with several types of cancers and variants in Trakl are linked to childhood absence epilepsy in humans. Despite the importance of Trakl in health and disease, the mechanisms of Trakl action remain unclear and the pathogenic effects of Trakl mutation are unknown. Here we report that Trakl has a crucial function in regulation of mitochondrial fusion. Depletion of Trakl inhibits mitochondrial fusion, result- ing in mitochondrial fragmentation, whereas overex- pression of Trakl elongates and enlarges mitochondria. Our analyses revealed that Trakl interacts and colocal- izes with mitofusins on the outer mitochondrial mem- brane and functions with mitofusins to promote mitochondrial tethering and fusion. Furthermore, Trakl is required for stress-induced mitochondrial hyperfu- sion and pro-survival response. We found that hyper- tonia-associated mutation impairs Trakl mitochondrial localization and its ability to facilitate mitochondrial tethering and fusion. Our findings uncover a novel function of Trakl as a regulator of mitochondrial fusion and provide evidence linking dysregulated mitochon- drial dynamics to hypertonia pathogenesis.
Hypertonia is a neurological dysfunction associated with a number of central nervous system disorders, including cerebral palsy, Parkinson＇s disease, dystonia, and epilepsy. Genetic studies have identified a homozygous truncation mutation in Trakl that causes hypertonia in mice. Moreover, elevated Trakl protein expression is associated with several types of cancers and variants in Trakl are linked to childhood absence epilepsy in humans. Despite the importance of Trakl in health and disease, the mechanisms of Trakl action remain unclear and the pathogenic effects of Trakl mutation are unknown. Here we report that Trakl has a crucial function in regulation of mitochondrial fusion. Depletion of Trakl inhibits mitochondrial fusion, result- ing in mitochondrial fragmentation, whereas overex- pression of Trakl elongates and enlarges mitochondria. Our analyses revealed that Trakl interacts and colocal- izes with mitofusins on the outer mitochondrial mem- brane and functions with mitofusins to promote mitochondrial tethering and fusion. Furthermore, Trakl is required for stress-induced mitochondrial hyperfu- sion and pro-survival response. We found that hyper- tonia-associated mutation impairs Trakl mitochondrial localization and its ability to facilitate mitochondrial tethering and fusion. Our findings uncover a novel function of Trakl as a regulator of mitochondrial fusion and provide evidence linking dysregulated mitochon- drial dynamics to hypertonia pathogenesis.
