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Updated: May 20, 2025
A Modified Simple Method for Induction of Myocardial Infarction in Mice
Published on: December 3, 2021
Stabilization of Transcription Factor, HIF-1α by Prolylhydroxylase 1 Knockout Reduces Cardiac Injury After Myocardial
Mahesh Thirunavukkarasu1, Seetur R Pradeep1, Babatunde Oriowo1
1Molecular Cardiology and Angiogenesis Laboratory, Department of Surgery, University of Connecticut School of Medicine, UConn Health, Farmington, CT 06030, USA.
Insights
PHD1 knockout in mice enhances blood vessel formation and improves heart function after myocardial infarction. This study highlights PHD1 inhibition as a potential therapeutic strategy for heart attack recovery.
Area of Science:
- Cardiovascular Biology
- Molecular Medicine
- Hypoxia Signaling
Background:
- Hypoxia-inducible factors (HIFs) regulate cellular responses to low oxygen and ischemic conditions.
- Prolyl hydroxylase domain (PHD) enzymes, including PHD1, regulate HIF stability.
- Investigating PHD1's role in myocardial infarction (MI) may reveal new therapeutic targets.
Purpose of the Study:
- To investigate the cardioprotective effects of PHD1 knockout against myocardial infarction in a mouse model.
- To analyze the impact of PHD1 deficiency on cardiac function, angiogenesis, and gene expression post-MI.
Main Methods:
- Myocardial infarction was induced via left anterior descending coronary artery ligation in wild-type and PHD1 knockout mice.
- Cardiac function was assessed using echocardiography.
- Vessel density, HIF-1α DNA binding activity, protein expression (HSPA12B), and gene expression (microarray) were analyzed.
Main Results:
- PHD1 knockout mice exhibited significantly increased capillary and arteriolar density post-MI.
- Echocardiography revealed improved ejection fraction and fractional shortening in PHD1 knockout mice 30 days post-MI.
- Increased HIF-1α DNA binding activity and HSPA12B expression were observed in PHD1 knockout mice post-MI.
Conclusions:
- PHD1 knockout promotes angiogenesis and enhances cardioprotection following myocardial infarction.
- The findings suggest that inhibiting PHD1 activates protective molecular pathways, improving cardiac recovery.
Abstract:
Inhibition of HIF-prolyl hydroxylases (PHD1, PHD2, and PHD3) causes the stabilization of hypoxia-inducible factor-1α and -2α (HIF-1α and HIF-2α) to regulate various cell signaling pathways. Hypoxia-inducible factor (HIF) is crucial in regulating signal responses mediated by hypoxia. HIF regulates the transcription of many genes involved in the response to hypoxia and ischemic insult. Our current work investigates the protective effects of PHD1 knockout in mice against myocardial infarction. Study Design: Myocardial infarction (MI) was induced by left anterior descending coronary artery (LAD) ligation (8-12-week-old mice) in both wild-type (WT) and PHD1 knockout (PHD1-/-) mice. WT sham (S) and PHD1-/-S group mice underwent surgery without LAD ligation. Thirty days post-surgery, cardiac functions were measured by echocardiogram. Mice in all the groups were euthanized at various time points for tissue collection post-MI 8 h (gel shift and microarray analysis), 4 days (Western blot analysis), 7 days (blood vessel density), or 30 days (histological analysis). For microarray analysis, WTMI and PHD1-/-MI group mices' heart tissue was used for RNA isolation, then hybridization to a GeneChip™ Mouse Gene 1.0 ST Array as per the manufacturer's instructions. Bioinformatic analysis was performed using the transcriptome analysis console (TAC) to generate a list of differentially regulated genes, followed by ingenuity pathway analysis. Results: The study findings revealed a significant increase in vessel density (capillary and arteriolar density) in the PHD1-/-MI mice compared to those with WTMI. The echocardiographic examination demonstrated that the PHD1-/-MI mice group had an increased ejection fraction and fractional shortening than the WT mice 30 days post-MI. HIF-1α DNA binding activity was higher in PHD1-/-MI mice than in WTMI. The Western blot analysis showed a significant increase in the expression of HSPA12B in the PHD1-/-MI compared to WTMI mice. Bioinformatic analysis using TAC software, Version 4.0.2.15 (1.5 fold, p < 0.05) showed 174 differentially regulated genes. Conclusions: In conclusion, our study showed PHD1 knockout activates several important molecules and signaling pathways, resulting in increased angiogenesis and cardioprotection against myocardial infarction.
