Gene expression profile for Gpt2 WT and Gpt2 KO mouse brain tissues with vehicle or dm-αKG treatment

Alpha-ketoglutarate (αKG) is required for chromatin demethylation but mechanisms controlling αKG abundance in the nucleus are poorly defined. We designed a biosensor to monitor this metabolite pool in human cells using an αKG-responsive cyanobacterial transcription factor, NtcA, and used it to identify genes that regulate αKG in the nucleus. We defined an inter-organelle pathway in which sequential mitochondrial activities of the GPT2 transaminase and SLC25A11 transporter supply nuclear αKG. In a mouse model of GPT2 Deficiency, an inborn error of metabolism, Gpt2 loss caused histone hypermethylation in the brain and dysregulated neurodevelopmental genes. Restoring αKG counteracted these changes and promoted mouse fitness. Our work provides a tool to directly monitor nuclear αKG and reveals nuclear αKG deficiency as a key pathogenic mechanism underlying GPT2 Deficiency.