Single Cell Transcriptomic Analysis Of Tafazzin Knockout Mice For Pathway And Therapeutic Discovery In Barth Syndrome

Barth Syndrome, a rare X-linked disorder affecting 1:300,000 live births, results from defects in Tafazzin, an acyltransferase that remodels cardiolipin and is essential for mitochondrial respiration. Barth Syndrome patients develop cardiomyopathy, muscular hypotonia and cyclic neutropenia during childhood, rarely surviving to middle age. At present, no effective therapy exists and downstream transcriptional effects of Tafazzin dysfunction are incompletely understood. To identify novel, cell-specific pathological pathways downstream of Tafazzin that mediate heart dysfunction, we performed snRNA-seq on mouse hearts deficient in Tafazzin. We generated libraries from four WT and four KO mouse hearts (10X Genomics Chromium) and performed next generation sequencing (Illumina NovaSeq S4), demultiplexing (CellRanger), doublet reduction (DoubletFinder), ambient RNA removal (SoupX), sample integration (Harmony), optimal clustering (ChooseR/Seurat), determined differentially expressed genes (DEGs; DESEQ2), and inferred a predicted cell-cell communication network (scLR). Surprisingly, DEGs were distributed heterogeneously, with cardiomyocytes, adipocytes, endothelial cells, fibroblasts and macrophages exhibiting the greatest number of DEGs between each genotype, while lymphocytes, lymphatic endothelium, pericytes, smooth muscle cells and mesothelial cells were mostly unaffected. Gene Ontology analysis showed cell specific effects such as altered amino acid and carbohydrate metabolism plus altered ion channel function in cardiomyocytes and common metabolic perturbations across all affected cell types. Analysis of Ligand-Receptor pair expression, to infer intercellular communication patterns, revealed WT adipocytes form the densest intercellular communication network, followed by WT cardiomyocytes. In the Tafazzin KO hearts, adipocyte significant intercellullar communication ceases, primarily through loss of PDGFRB interactions, while cardiomyocytes remain largely unperturbed. These findings suggest that adipocyte mitochondria may be most sensitive to mitochondrial Tafazzin deficiency and rescuing adipocyte mitochondrial dysfunction may provide therapeutic benefit in Barth Syndrome patients.