NOD1, a new player in cardiac function and calcium handling

Area of Science:

• Cardiovascular Biology
• Innate Immunology
• Molecular Cardiology

Background:

• Inflammation significantly impacts cardiovascular disease (CVD) and its complications.
• Nucleotide-binding oligomerization domain-like receptors (NLRs) are crucial in the cardiac response to injury.
• The specific role of Nucleotide-binding oligomerization domain containing 1 (NOD1) in cardiac function remains unclear.

Purpose of the Study:

• To investigate the functional role of Nucleotide-binding oligomerization domain containing 1 (NOD1) in the heart.
• To determine if selective NOD1 activation affects cardiac function and calcium (Ca2+) signaling.

Main Methods:

• Mice were treated with a selective NOD1 agonist (C12-iE-DAP).
• Cardiac function, including ejection fraction and fractional shortening, was assessed.
• Cardiomyocyte Ca2+ handling, Ca2+ cycling, and expression of key proteins were analyzed.
• Experiments were conducted in both wild-type and NOD1 knockout mice, with and without NF-κB inhibition.

Main Results:

• NOD1 activation by C12-iE-DAP led to significant cardiac dysfunction.
• Impaired Ca2+ transients, reduced Ca2+ load, and altered expression of Ca2+-handling proteins were observed in cardiomyocytes.
• NOD1 activation induced 'diastolic Ca2+ leak' via increased Ca2+ spark frequency and RyR2 over-phosphorylation.
• These effects were NOD1-dependent and mitigated by NF-κB inhibition.

Conclusions:

• NOD1 activation impairs cardiac function by disrupting excitation-contraction coupling.
• NF-κB activation is a key mechanism underlying NOD1-induced cardiac dysfunction.
• NOD1 emerges as a novel pro-inflammatory regulator in cardiovascular function.