Fumarate induces vesicular release of mtDNA to drive innate immunity

Fumarate Hydratase (FH) is an enzyme of the Tricarboxilic Acid Cycle (TCA) that catalyzes the conversion of fumarate into malate. In the last decade, studies have revealed FH as a bona fide tumour suppressor whose mutations cause Hereditary leiomyomatosis and renal cell carcinoma (HLRCC). Loss of FH in the kidney elicits several oncogenic signalling cascades through the accumulation of the oncometabolite fumarate. Yet, whilst the long-term consequences of FH loss have been extensively described, the acute response to FH loss has not been investigated due, in part, to the lack of a suitable model. Here, we generated a new inducible mouse model to investigate the chronology of the murine homologue of FH, Fh1, loss in the adult kidney. Mice were of mixed genetic background C57BL/6 and 129/SvJ. Fh1fl/fl (Pollard et al., 2008) and R26Creert2 (Hameyer et al., 2007) mice were crossed to generate animals homozygous for the conditional LoxP-exon3/4-LoxP Fh1 allele and expressing the Cre–recombinase-ert2 fusion under control of the ROSA26 promoter (Fh1 fl/fl; R26 Creert2/Creert2). Littermate controls lacked the LoxP-exon3/4-LoxP allele but also expressed the Cre-ert2 allele under the control of the ROSA26 promoter (Fh1 +/+; R26 Creert2/Creert2). Control mice were induced and sacrificed at the same time as their experimental littermates. Briefly, 12-weeks old animals received 3 x 2mg tamoxifen via intraperitoneal injection (every other day; starting at day 0 of induction), the kidneys were collected at day 5 and day 10 post-induction and total RNA was prepared for sequencing.