Desmoglein 2 mutant mice develop cardiac fibrosis and dilation

Cardiomyocyte adhesion is crucial for maintaining heart structure and function. Prior research has shown that desmosomes, which are part of intercalated discs, play a key role in linking adjacent heart cells. These structures rely on desmosomal cadherins, including desmoglein 2, to anchor the extracellular matrix to the cytoskeleton. While the role of desmoglein 2 in skin and epithelial tissues is well established, its function in cardiac tissue remains less clear. No prior work had resolved how mutations in desmoglein 2 specifically affect heart morphology and function. That uncertainty drove this investigation into the consequences of desmoglein 2 mutations in mice. This gap motivated the use of genetic models to explore the pathophysiology of desmosomal defects in the heart. This paper's contribution lies in linking desmoglein 2 mutations to cardiac fibrosis and dilation. This study adds to the understanding of inherited heart diseases linked to desmosomal proteins.

The aim of this research was to investigate how desmoglein 2 mutations impact cardiac structure and function. The specific problem addressed is the lack of clarity on the role of desmoglein 2 in cardiomyocyte adhesion and heart disease progression. The motivation stems from the known association between desmosomal protein mutations and inherited heart conditions like arrhythmogenic right ventricular cardiomyopathy. The study sought to determine whether desmoglein 2 is essential for maintaining cardiac integrity. The researchers proposed to generate mutant mice with a deletion in the extracellular domain of desmoglein 2. The goal was to observe the resulting cardiac changes and compare them to human disease phenotypes. This approach allowed for a direct assessment of desmoglein 2's role in heart function. The study aimed to clarify whether desmoglein 2 mutations cause fibrosis and dilation in mice.

The study used a genetic approach to create mutant mice lacking a portion of the extracellular domain of desmoglein 2. Cardiac morphology was assessed using histological techniques to evaluate fibrotic lesions and cardiomyocyte death. Ventricular dilation was monitored over time to track disease progression. Gene expression changes were analyzed using mRNA quantification for markers like c-myc, ANF, BNF, CTGF, and GDF15. The researchers compared the mutant mice to wild-type controls at multiple time points. Histological examination included calcifying necrosis and fibrotic tissue replacement assessments. The proliferative activity of fibrotic lesions was measured in young and older mutants. This approach allowed the team to correlate structural changes with molecular markers of cardiac stress.

Most live-born mutant mice had normal cardiac morphology at 2 weeks. However, some mice developed extensive fibrotic lesions. Later in life, mutants exhibited ventricular dilation and cardiac insufficiency. Histological analysis revealed cardiomyocyte death via calcifying necrosis and replacement by fibrous tissue. Fibrotic lesions in 2-week-old mutants were highly proliferative. In older mutants, fibrotic lesions showed little proliferation, indicating scar tissue formation. Gene expression analysis showed increased levels of c-myc, ANF, BNF, CTGF, and GDF15. These markers indicate cardiac stress, remodeling, and heart failure progression.

The desmoglein 2-mutant mice displayed features of dilative cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. The findings suggest that desmoglein 2 mutations may contribute to cardiac fibrosis and dilation in mice. The observed fibrotic lesions and ventricular dilation align with human heart diseases linked to desmosomal protein mutations. The study supports a role for desmoglein 2 in maintaining cardiomyocyte adhesion and preventing cardiac dysfunction. The researchers propose that the loss of desmoglein 2 function may disrupt intercellular connections in the heart. The progression of fibrosis correlates with increased expression of cardiac stress markers. The results suggest that desmoglein 2 mutations may be a cause of inherited heart disease in humans. This study provides evidence linking desmoglein 2 to cardiac pathology.