Sex-specific response to A1BG loss results in female dilated cardiomyopathy

Figures

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  Fig. 1. Loss of A1BG and Its Sex-Differential Cardiac Effects on the Left Ventricle. (A) Representative images of (A) male control, (B) female control, (C) male A1bgCM/CM (A1BG KO), and (D) female A1bgCM/CM (A1BG KO) hearts stained with hematoxylin and eosin. (E) Echocardiogram data (n = 11 mice of each genotype) for left ventricular posterior wall thickness in (E) systole (LVPW; s) and (F) diastole (LVPW; d). (G) Graph comparing female control and female A1BG KO mice at 4–6 week timepoint and 6 month for (G) ejection fraction (EF), (H) fractional shortening (FS), (I) left ventricular (LV) mass, (J) LV interior diameter in systole, and (K) diastole, (L) interventricular septum thickness, (M) LV volume in systole, and (N) diastole, and (O) LV posterior wall thickness in systole. Significance was determined by ANOVA with Tukey’s post-hoc test. **** indicates p < 0.0001, *** indicates p < 0.001, ** indicates p < 0.01, * indicates p < 0.05

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  Fig. 2. Female hearts, but male hearts, regulate gene expression related to cardiac metabolism and DCM. Volcano plots of differentially expressed genes in (A) female KO vs. female control group and (B) male KO vs. male control group. Cutoffs used were adjusted p-value < 0.05, and log2 fold change ≥ 0.5 (C) Venn diagram depicting genes downregulated (left) and upregulated (right) in A1bgCM/CM (A1BG KO) mice in both males and females. Overlap indicates genes similarly regulated in both sexes in response to A1bgCM/CM (A1BG KO) (D) Pathway analysis of differentially expressed genes in response to A1bgCM/CM (A1BG KO). (E) Heat map of selected dysregulated genes in female A1bgCM/CM (A1BG KO) and control mice

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  Fig. 3. A1BG is required in females for the formation of the cardiac intercalated disc. (A-D) Transmission electron micrograph images of (A) male control, (B) female control, (C) male A1bgCM/CM (A1BG KO), and female A1bgCM/CM (A1BG KO) (D) hearts taken at 50000x magnification. (E) Quantification of differences in cardiomyocyte intercalation, taken as a ratio of the total length of cell border divided by straight line length (n = 2 hearts per genotype with > 10 intercalated discs per heart analyzed. (F) PR interval duration in male and female A1bgCM/CM (A1BG KO, control) and Tnnt2-Cre; A1bgCM/CM (A1BG KO) mice (n = 14 mice per genotype). Significance was determined by ANOVA, followed by Tukey’s test. * Indicates p < 0.05 between indicated groups, **** indicates p < 0.0001 between indicated groups

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  Fig. 4. A1BG is an extracellular matrix protein. (A) Schematic of A1BG genomic locus, mRNA transcript, and protein with key domains indicated. Amino acid numbers are noted below, and disulfide bonds are above the diagram. (B) AlphaFold3 structure prediction of A1BG. (C) AlphaFold 3 prediction of human A1BG (blue) aligned with mouse A1bg (green) with root mean square deviation indicated (RMSD) (D) Immunohistochemistry staining of female atria with antibodies for tropomyosin (TMY, green), A1BG (red), and DAPI (blue)

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  Fig. 5. Female and male A1BG cardiomyocyte interactome. (A) Schematic of A1BG Rosa26 genomic locus for generation of CM-A1BG3XHA mice. (B) Schematic depicting immuno-purification of A1BG in male and female mouse hearts to identify the A1BG interactome by mass spectrometry. Cutoffs were Log fold change > 1.5 A1BG IP vs. non-HA control) (C) Proteins enriched in the (C) female and (D) male A1BG interactome with associated gene ontology circled