Calreticulin induces dilated cardiomyopathy

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Endoplasmic Reticulum Biology

Background:

• Calreticulin is crucial for embryonic heart development but downregulated in adult hearts.
• Adult hearts normally have minimal calreticulin levels.
• The role of calreticulin in the adult heart remained largely unexplored.

Purpose of the Study:

• To investigate the functional role of calreticulin in the adult mammalian heart.
• To determine the consequences of calreticulin re-expression in adult cardiac tissue.

Main Methods:

• Generation of an inducible transgenic mouse model with cardiac-specific calreticulin upregulation via Cre/loxP system.
• Echocardiography to assess cardiac function (systolic, diastolic, valve function).
• Analysis of gene and protein expression related to calcium signaling and cardiac structure.

Main Results:

• Calreticulin upregulation in adult hearts led to impaired left ventricular systolic and diastolic function.
• Mitral valve function was also compromised in transgenic mice.
• Downregulation of key calcium-handling proteins and altered expression of gap junction proteins were observed.

Conclusions:

• Overexpression of calreticulin in adult hearts induces cardiomyopathy and heart failure in vivo.
• Cardiac dysfunction is linked to altered calcium handling, gap junction alterations, and left ventricle remodeling.
• Calreticulin re-expression significantly disrupts adult cardiac homeostasis.