Related Experiment Video
Updated: Aug 30, 2026
A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion
Published on: July 17, 2012
Roles for alphaB-crystallin and HSPB2 in protecting the myocardium from ischemia-reperfusion-induced damage in a KO
Lisa E Morrison1, Ross J Whittaker, Robert E Klepper
1San Diego State Univ., San Diego, CA 92182, USA.
Abstract:
Overexpression studies have shown that the small heat shock proteins (sHSP) protect the myocardium from ischemia-reperfusion (I/R)-induced damage. However, gene deletion studies are necessary to demonstrate whether sHSPs are required for protection. The genes for alphaB-crystallin (alphaBC) and HSPB2, two sHSPs that are expressed in high levels in the heart, are in close proximity to one another; as a result, both genes were disrupted in a recently generated knockout (KO) mouse line. The alphaBC/HSPB2 KO mouse line is currently the only model that features disruption of sHSPs normally expressed in the heart. Accordingly, we examined the cardiac morphology, function, and response to I/R-induced stress in alphaBC-HSPB2 KO mice. Initial gross, light microscopic and echocardiographic characterization showed that the morphological and functional properties of hearts from adult KO mice were indistinguishable from age-matched wild-type (WT) mice. Electron microscopy showed that, compared with WT mouse hearts, KO mouse heart sarcomeres were relatively normal. Isolated perfused KO mouse hearts displayed normal contractility; however, when compared with WT, after I/R, KO mouse hearts exhibited a twofold reduction in contractile recovery, as well as increased necrosis and apoptosis. Additionally, when compared with WT, KO mouse hearts exhibited 43% less reduced glutathione, which is known to protect from I/R-induced damage. Thus, whereas neither alphaBC nor HSPB2 is essential for myocardial development and function under nonstressful conditions, one or both are required for maximal functional recovery and protection from I/R-induced necrosis and apoptosis.
Insights
Small heat shock proteins (sHSPs) like alphaB-crystallin and HSPB2 are crucial for heart protection against ischemia-reperfusion injury. Their absence in knockout mice led to significantly impaired recovery and increased cell death after stress.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Stress Response Mechanisms
Background:
- Small heat shock proteins (sHSPs) are known to protect the myocardium from ischemia-reperfusion (I/R) injury.
- Gene deletion studies are essential to confirm the necessity of sHSPs for cardiac protection.
Purpose of the Study:
- To investigate the role of alphaB-crystallin (alphaBC) and HSPB2, two cardiac-expressed sHSPs, in protecting the heart from I/R-induced damage.
- To characterize the cardiac function and response to I/R stress in a novel alphaBC/HSPB2 double knockout (KO) mouse model.
Main Methods:
- Generation and characterization of alphaBC/HSPB2 double KO mice.
- Assessment of cardiac morphology, function (echocardiography, isolated heart perfusion), and response to I/R stress.
- Histological analysis (necrosis, apoptosis) and measurement of reduced glutathione levels.
Main Results:
- AlphaBC/HSPB2 KO mice exhibited normal cardiac morphology and function under non-stressful conditions.
- KO hearts showed a twofold reduction in contractile recovery, increased necrosis and apoptosis following I/R compared to wild-type (WT).
- KO hearts had significantly lower levels of reduced glutathione, a known protective antioxidant.
Conclusions:
- Neither alphaBC nor HSPB2 is essential for normal myocardial development or function.
- One or both sHSPs are required for maximal functional recovery and protection against I/R-induced cardiac damage, necrosis, and apoptosis.
