PT  - JOURNAL ARTICLE
AU  - Lindsey Van Haute
AU  - Song-Yi Lee
AU  - Beverly J. McCann
AU  - Christopher A. Powell
AU  - Dhiru Bansal
AU  - Caterina Garone
AU  - Sanghee Shin
AU  - Jong-Seo Kim
AU  - Michaela Frye
AU  - Joseph G. Gleeson
AU  - Eric Miska
AU  - Hyun-Woo Rhee
AU  - Michal Minczuk
TI  - NSUN2 introduces 5-methylcytosines in mammalian mitochondrial tRNAs
AID  - 10.1101/626960
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 626960
4099  - http://biorxiv.org/content/early/2019/05/03/626960.short
4100  - http://biorxiv.org/content/early/2019/05/03/626960.full
AB  - Maintenance and expression of mitochondrial DNA is indispensable for proper function of the oxidative phosphorylation machinery. Post-transcriptional modification of mitochondrial RNA has emerged as one of the key regulatory steps of human mitochondrial gene expression. Mammalian NOP2/Sun RNA Methyltransferase Family Member 2 (NSUN2) has been characterised as an RNA methyltransferase that introduces 5-methylcytosine (m5C) in nuclear-encoded tRNAs, mRNAs, microRNA and noncoding RNAs. In these roles, NSUN2 has been associated with cell proliferation and differentiation. Pathogenic variants in NSUN2 have been linked with neurodevelopmental disorders. Here we employ spatially restricted proximity labelling and immunodetection to demonstrate that NSUN2 is imported into the matrix of mammalian mitochondria. Using three genetic models for NSUN2 inactivation – knockout mice, patient-derived fibroblasts and CRISPR/Cas9 knockout in human cells – we show that NSUN2 in necessary for the generation of m5C at positions 48, 49 and 50 of several mammalian mitochondrial tRNAs. Finally, we show that inactivation of NSUN2 does not have a profound effect on mitochondrial tRNA stability and oxidative phosphorylation in differentiated cells. We discuss the importance of the newly discovered function of NSUN2 in the context of human disease.