Mitochondrial permeability transition and calcium uptake were increased in DKO cardiomyocytes and mitochondrial respiration rate using skinned fibers from DKO myocardium were BYL719 in vivo reduced compared with wild type. Therefore, beyond the DKO model affecting both CRYAB and HSPB2 expression, a new mouse model that targets specifically hspb2 is required to determine the distinct tissue-specific functions of HSPB2 in vivo. The present study reports the creation of a conditional floxed hspb2 allele and the production of mice with a cardiac-specific knockout of hspb2. Our data reveal that the absence of HSPB2 in the heart does not significantly affect the cardiac hypertrophic response to pressure overload stimuli, but that HSPB2 deficiency depresses mitochondrial fatty acid betaoxidation and ATP production under these conditions. In this study, we describe a new mouse model characterized by the cardiac specific deletion of the hspb2 gene. Under normal conditions, HSPB2cKO did not exhibit any obvious cardiac anomaly and this is consistent with the observations made with the DKO animals, which were deficient in both hspb2 and hspb5. We further demonstrated that lack of HSPB2 did not modify the cardiac response to pressure overload in response to either mild or severe stress. Because the expression levels for some other sHSPs such as HSPB1, HSPB5 and HSPB6 were not visibly altered, absence of phenotype in HSPB2cKO does not seem to be linked to major compensatory responses. As the present study analyzes a cardiac-specific knockout of hspb2, we could not definitively address the role of HSPB2 deficiency in other organs especially in skeletal muscles that harbor high levels of HSPB2 expression. The superfamily of small MW HSPs has been implicated in diverse functions and biological roles ranging from cellular immunity to oncogenesis to cardiomyopathy and heart failure. Whereas both cryab and hspb2 are arranged adjacently in the genome, we have hypothesized the existence of tissue-specific functions for their expression, under the control of myogenic regulators that drive high levels of endogenous expression in skeletal muscle and the heart. Unlike distinct mutations in human CryAB that have been linked to various inherited multisystem diseases, HSPB2 is not only the most divergent sHSP family but its biological function remains unknown. We confirm that HSPB2, like CryAB, is dispensable for cardiac function and maintenance of myocardial integrity. Similarly the knockout of hspb1, another sHSP highly expressed during heart development did not provoke any major disturbance in cardiac anatomy or function as evidenced by the normal lifespan of those animals. Although prior studies by other investigators have shown that isolated and intact hearts lacking both CRYAB and HSPB2 exhibit severe contractile dysfunction and increased myocardial injury in response to ischemia/reperfusion ex vivo, our laboratory has reported increased resistance of DKO hearts to in situ and ex vivo ischemic conditions compared with wild-type controls. Such studies, therefore, have provided confounding insights about the functional roles of these two sHSPs in ischemic cardioprotection and in no study could the specific role of HSPB2, in particular, be unambiguously assigned. In addition, we found that HSPB2 appears to be required for systolic performance and for maintaining cardiac energetics in the isolated perfused mouse heart. To address these unmet needs, we have advocated the use of genetic tools to unmask potential novel and non-redundant functions between CryAB and HSPB2 in terms of cardiac mechanics and energetics.