Fig. 1: Mtfp1 deletion in cardiomyocytes causes dilated cardiomyopathy and middle-aged death in mice.

a AlphaFold prediction of MTFP1 at the inner mitochondrial membrane (IMM). DRP1 binds to its receptors MFF or MiD49/51 to initiate mitochondrial constriction. IMM fission occurs with mtDNA replication mediated by TFAM and POLG2. S-OPA1 accumulation by OMA1 accelerates fission. Figure created with BioRender. b Generation of a cardiomyocyte-specific Mtfp1 KO (cMKO) mouse model. c Mtfp1 mRNA expression (RNAseq arbitrary units; AU) in heart tissue of WT (n = 5) and cMKO (n = 5) mice at 8 weeks (Supplementary Data 2). Data represent mean ± SD; 2-tailed unpaired Student’s t-test, ****p < 0.0001. d Quantification of immunoblot analysis of cardiac lysates from WT (n = 5) and cMKO (n = 5) male mice at 8 weeks using the indicated antibodies. Data represent mean ± SD; Unpaired t-test, **p < 0.01. e MTFP1 protein expression in cardiac tissue of WT (n = 4) and cMKO (n = 4) at 18 weeks measured by mass spectrometry (MS) (Supplementary Data 1). Data represent mean ± SD; 2-tailed unpaired Student’s t-test, ***p < 0.001. f Kaplan-Meier survival curve of WT (n = 9) and cMKO (n = 15) male mice. Median lifespan of cMKO mice is 26.4 weeks. g–l Longitudinal echocardiography of WT and cMKO male mice from 10 to 34 weeks of age. g Representative M-Mode echocardiographic images of left ventricles from WT (left) and cMKO (right) of male mice at 34 weeks. h Left ventricular ejection fraction (% LVEF) i Systolic interventricular septum thickness (IVSs, mm), j Left ventricle posterior wall thickness at systole (LVPWs, mm), k Left ventricle end diastolic diameter (LVDD, mm), l Left ventricle end systolic diameter (LVSD, mm) of WT and cMKO male mice at indicated ages. Data represent mean ± SD; 2way Anova–Sidak’s multiple comparison test: 10 week WT (n = 13) vs cMKO (n = 18); 14 week WT (n = 4) vs. cMKO (n = 6); 18 week WT (n = 4) vs cMKO (n = 7) except for LVEF: WT (n = 10) vs cMKO (n = 13); 22 week WT (n = 4) vs cMKO (n = 6); 30 week WT (n = 3) vs cMKO (n = 7); 34 week WT (n = 4) vs. cMKO (n = 10): *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. m Representative histological images of cardiac short axis view of WT (n = 4) and cMKO (n = 4) at 34 weeks. H&E (left), Massons’s Trichrome (middle) and Picrosirius red (right) staining show cardiac remodeling and collagen deposition within the myocardium of cMKO mice. Scale bar 500 µM. n Cardiac troponin-I (cTNI) measured in serum of WT and cMKO male mice at 18 [WT (n = 6) vs cMKO (n = 6)] and 34 weeks [WT (n = 11) vs cMKO (n = 20)]. Data represent mean ± SD; 2-tailed unpaired Student’s t-test at 18 weeks and 34 weeks (w); ***p < 0.001. o Myosin light chain 1 (MLC-1) levels measured in serum of WT and cMKO mice at 18 [WT (n = 5) vs cMKO (n = 6)] and 34 weeks (w) [WT (n = 11) vs cMKO (n = 17)]. Data represent mean ± SD; 2-tailed unpaired Student’s t-test at 18 w and 34 w; **p < 0.01 and ***p < 0.001. p Volcano plots generated from the RNAseq analysis (Supplementary Data 2) of the differentially expressed genes in cardiac tissue of WT and cMKO male mice at 8 (left) and 18 weeks (right). q Numbers of genes up-regulated and down-regulated in cMKO male mice at 8 (blue) and 18 (pink) weeks (w) within the gene ontology (GO) term: metabolic process (left), mitochondrial genes (MitoCarta, middle) and inflammation (right) obtained from RNAseq analysis (Supplementary Data 2). r Expression of indicated profibrotic genes in heart tissue of WT (n = 6) and cMKO (n = 6) male mice at 18 weeks by RNAseq (arbitrary units; AU). Data represent mean ± SD; 2-tailed unpaired Student’s t-test; ***p < 0.001, ****p < 0.0001.