Conditional HIF-1alpha expression produces a reversible cardiomyopathy.

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Transcriptional Regulation

Background:

• Hypoxia-Inducible Factor-1 (HIF-1) regulates tissue responses to low oxygen.
• HIF-1 is a heterodimeric transcription factor crucial for cellular adaptation.

Purpose of the Study:

• To investigate the role of enhanced HIF-1 activity in adult heart function.
• To determine if HIF-1 directly causes cardiac contractile dysfunction.

Main Methods:

• Generated a mouse model with inducible cardiomyocyte-specific HIF-1alpha expression.
• Utilized long-oligo microarrays to identify dysregulated transcripts.
• Assessed cardiac function, calcium flux, SERCA expression, and protein levels.

Main Results:

• Inducible HIF-1alpha expression led to progressive cardiac dysfunction.
• Cardiac function recovered upon cessation of transgene expression.
• Identified 162 dysregulated transcripts, including reduced SERCA expression and impaired calcium reuptake.
• Observed a 46% reduction in SERCA transcript and 92% reduction in SERCA protein.

Conclusions:

• Enhanced HIF-1 activity is sufficient to induce contractile dysfunction in the adult heart.
• Impaired calcium reuptake by myocytes contributes to cardiac dysfunction.
• Suggests HIF-1 may play a direct role in contractile dysfunction in ischemic cardiomyopathy.