SUCLG1 restricts POLRMT succinylation to enhance mitochondrial biogenesis and leukemia progression.

Mitochondria are cellular powerhouses that generate energy through the electron transport chain (ETC). The mitochondrial genome (mtDNA) encodes essential ETC proteins in a compartmentalized manner, however, the mechanism underlying metabolic regulation of mtDNA function remains unknown. Here, we report that expression of tricarboxylic acid cycle enzyme succinate-CoA ligase SUCLG1 strongly correlates with ETC genes across various TCGA cancer transcriptomes. Mechanistically, SUCLG1 restricts succinyl-CoA levels to suppress the succinylation of mitochondrial RNA polymerase (POLRMT). Lysine 622 succinylation disrupts the interaction of POLRMT with mtDNA and mitochondrial transcription factors. SUCLG1-mediated POLRMT hyposuccinylation maintains mtDNA transcription, mitochondrial biogenesis, and leukemia cell proliferation. Specifically, leukemia-promoting FMS-like tyrosine kinase 3 (FLT3) mutations modulate nuclear transcription and upregulate SUCLG1 expression to reduce succinyl-CoA and POLRMT succinylation, resulting in enhanced mitobiogenesis. In line, genetic depletion of POLRMT or SUCLG1 significantly delays disease progression in mouse and humanized leukemia models. Importantly, succinyl-CoA level and POLRMT succinylation are downregulated in FLT3- mutated clinical leukemia samples, linking enhanced mitobiogenesis to cancer progression. Together, SUCLG1 connects succinyl-CoA with POLRMT succinylation to modulate mitochondrial function and cancer development. Synopsis: Whether mitochondrial DNA function is affected by cellular metabolism remains poorly understood. Here, the Krebs cycle enzyme succinate-CoA ligase (SUCLG1) is shown to restrict succinylation of mitochondrial RNA polymerase (POLRMT) and thereby sustain mitochondrial transcription. This mechanism is relevant for mutant FLT3-driven leukemogenesis. SUCLG1 reduces succinyl-CoA levels to restrict POLRMT succinylation. K622 succinylation suppresses POLRMT activity. FLT3 mutations regulate SUCLG1 to activate POLRMT. Mutant FLT3 alters nuclear transcription to remodel mitochondrial biogenesis. Genetic depletion of POLRMT or SUCLG1 delays leukemia progression in mice and humanized models. Krebs cycle succinate-CoA ligase targets mitochondrial RNA polymerase and mtDNA transcription supporting mutant FLT3-driven blood cancer. [ABSTRACT FROM AUTHOR]