Alpha B-crystallin suppresses pressure overload cardiac hypertrophy

Area of Science:

• Cardiology
• Molecular Biology
• Biochemistry

Background:

• AlphaB-crystallin (CryAB) is a small heat shock protein (HSP) abundant in cardiomyocytes, known to protect against ischemia/reperfusion injury.
• The role of CryAB and other HSPs in cardiac responses to mechanical overload remains largely unknown.

Purpose of the Study:

• To investigate the role of CryAB in cardiac responses to mechanical overload.
• To determine the impact of CryAB overexpression and ablation on cardiac function and hypertrophy.

Main Methods:

• Utilized nontransgenic, CryAB-overexpressing, and CryAB/HSPB2-ablated mice subjected to transverse aortic constriction (TAC) or sham surgery.
• Assessed cardiac responses through fetal gene expression profiling, cardiac function analysis, and morphometry.
• Investigated CryAB's effect on NFAT transactivation in cultured cardiomyocytes.

Main Results:

• CryAB overexpression was benign, while CryAB/HSPB2 ablation led to cardiac hypertrophy and malfunction.
• CryAB overexpression attenuated TAC-induced cardiac hypertrophy and NFAT transactivation.
• CryAB/HSPB2 knockout mice exhibited increased baseline NFAT transactivation and developed cardiac insufficiency post-TAC.

Conclusions:

• CryAB suppresses cardiac hypertrophic responses, likely by attenuating NFAT signaling.
• CryAB and/or HSPB2 are essential for normal cardiac function and adaptation to stress.