Heart rhythm genomic fabric in hypoxia

Area of Science:

• Cardiovascular Physiology
• Molecular Biology
• Genetics

Background:

• Chronic hypoxia, both constant (CCH) and intermittent (CIH), is implicated in cardiovascular dysfunction.
• The precise molecular mechanisms by which hypoxia impacts heart rhythm remain incompletely understood.
• Heart rhythm determinants (HRDs) encompass a complex network of genes controlling cardiac function and development.

Purpose of the Study:

• To investigate the molecular mechanisms underlying heart rhythm alterations induced by early-life CCH and CIH.
• To analyze the expression, control, maturational profile, and intercoordination of 54 genes encoding HRDs.
• To identify novel genes and pathways involved in hypoxia-induced cardiac arrhythmias.

Main Methods:

• Analysis of 54 heart rhythm determinant (HRD) genes in 36 mice exposed to normal, CCH, or CIH conditions for 1, 2, or 4 weeks during early life.
• Utilized Gene Prominence Analysis to rank genes based on expression stability and network interactions.
• Examined gene expression levels, control mechanisms, maturational profiles, and intercoordination within the HRD network.

Main Results:

• A complex gene network controlling heart rate, inotropy, development, receptors, ion channels, transporters, ankyrins, epigenetic modulators, and intercalated disc components was identified.
• This gene network undergoes remodeling during maturation and is substantially and differentially altered by CIH and CCH.
• Gene Prominence Analysis confirmed the HRD status of epigenetic modulators and intercalated disc proteins not previously linked to arrhythmia.

Conclusions:

• Early-life exposure to chronic hypoxia (CCH and CIH) significantly remodels the heart's molecular network controlling rhythm.
• Intercalated disc components and epigenetic modulators emerge as novel players in hypoxia-induced cardiac rhythm disturbances.
• Understanding these molecular alterations is crucial for developing therapeutic strategies against hypoxia-related arrhythmias.