Cardiomyopathy is the predominant defect in Barth syndrome (BTHS) and is caused by a mutation of the X-linked Tafazzin (TAZ) gene, which encodes an enzyme responsible for remodeling mitochondrial cardiolipin. Despite the known importance of mitochondrial dysfunction in BTHS, how specific TAZ mutations cause diverse BTHS heart phenotypes remains poorly understood. We generated a patient-tailored CRISPR/Cas9 knock-in mouse allele (Taz^PM) that phenocopies BTHS clinical traits. As Taz^PM males express a stable mutant protein, we assessed cardiac metabolic dysfunction and mitochondrial changes and identified temporally altered cardioprotective signaling effectors. Specifically, juvenile Taz^PM males exhibit mild left ventricular dilation in systole but have unaltered fatty acid/amino acid metabolism and normal adenosine triphosphate (ATP). This occurs in concert with a hyperactive p53 pathway, elevation of cardioprotective antioxidant pathways, and induced autophagy-mediated early senescence in juvenile Taz^PM hearts. However, adult Taz^PM males exhibit chronic heart failure with reduced growth and ejection fraction, cardiac fibrosis, reduced ATP, and suppressed fatty acid/amino acid metabolism. This biphasic changeover from a mild-to-severe heart phenotype coincides with p53 suppression, downregulation of cardioprotective antioxidant pathways, and the onset of terminal senescence in adult Taz^PM hearts. Herein, we report a BTHS genotype/phenotype correlation and reveal that absent Taz acyltransferase function is sufficient to drive progressive cardiomyopathy.

Overall survival of acute myeloid leukemia (AML) remains limited. Inhibitors of the master mitotic kinase PLK1 have emerged as promising therapeutics, demonstrating efficacy in an undefined subset of patients with AML. However, the clinical success of PLK1 inhibitors remains hindered by a lack of predictive biomarkers. The Fanconi anemia (FA) pathway, a tumor-suppressive network comprised of at least 22 genes, is frequently mutated in sporadic AML. In this study, we demonstrate that FA pathway disruption sensitizes AML cells to PLK1 inhibition. Mechanistically, we identify novel interactions between PLK1 and both FANCA and FANCD2 at mitotic centromeres. We demonstrate that PLK1 inhibition impairs recruitment of FANCD2 to mitotic centromeres, induces damage to mitotic chromosomes, and triggers mitotic collapse in FANCA-deficient cells. Our findings indicate that PLK1 inhibition targets mitotic vulnerabilities specific to FA pathway–deficient cells and implicate FA pathway mutations as potential biomarkers for the identification of patients likely to benefit from PLK1 inhibitors. Significance: This work demonstrates that FA pathway mutations, which are frequently observed in sporadic AML, induce hypersensitivity to PLK1 inhibition, providing rationale for a novel synthetic lethal therapeutic strategy for this patient population.

Supplementary Data from PLK1 Inhibition Induces Synthetic Lethality in Fanconi Anemia Pathway–Deficient Acute Myeloid Leukemia

FANCA-deficiency sensitizes RS4;11 acute lymphoblastic leukemia cell line to PLK1 inhibition.

Inhibition of PLK1 induces mitotic failure and apoptosis in the FANCA-deficient hTERT-RPE1 cell line. A, Representative Western blot showing FANCA expression in control (Scr.Ctrl.) cells vs. FANCA-KD (shFANCA) hTERT-RPE1 cells after 48 hours of doxycycline (Dox) treatment. B, Concentration-dependent survival (%) of shFANCA and Scr.Ctrl cells treated with volasertib and onvansertib for 3 days. Cell viability was measured by CellTiter-Glo assay. Representative graph shows the mean ± SEM cell survival (%) compared with vehicle. P values were calculated by two‐way ANOVA. C, Concentration-dependent cellular apoptosis (fold change) of shFANCA and Scr.Ctrl. hTERT-RPE1 cells treated with volasertib for 3 days. Caspase 3/7 activity was measured by Caspase-Glo 3/7 assay. Representative graph shows the mean ± SEM caspase 3/7 activity (fold change) compared with vehicle. P values were calculated by two‐way ANOVA. D, Experimental design and a representative Western blot showing increased cyclin B1 and γH2AX in shFANCA vs. Scr.Ctrl. hTERT-RPE1 cells. E, Experimental design and representative live-cell imaging images of shFANCA and Scr.Ctrl. hTERT-RPE1 cells stably expressing mCherry–tubulin (red) and GFP–H2B (green) after DMSO and volasertib treatment. Scale bars in the image panels represent 0.03 μm. Representative graph showing quantification of cells undergoing mitotic collapse and cytokinesis failure (n = 50 cells per group). Graph shows the mean ± SEM. P values were calculated by one‐way ANOVA. F, Representative IF images show γH2AX foci (red) and UFBs (RPA70, green) in shFANCA and Scr.Ctrl. mitotic hTERT-RPE1 cells after vehicle and volasertib (20 nmol/L) treatment. Scale bars in the image panels represent 2 μm. Representative graph showing quantification of γH2AX foci (n ≥ 10 cells per group) in DMSO-treated metaphase (+) cells vs. volasertib-treated (20 nmol/L) metaphase-collapsed (#) cells. Graph shows the mean ± SEM. P values were calculated by one‐way ANOVA. All graphs are representatives of at least three independent experiments.