Mutation in Integrin-Linked Kinase (ILKR211A) and Heat-Shock Protein 70 Comprise a Broadly Cardioprotective Complex

Rationale

Integrin-linked kinase (ILK) has been proposed as a novel molecular target that has translational potential in diverse cardiac diseases, since its upregulation promotes a broadly cardioprotective phenotype. However, ILK has been implicated as both a cardioprotective and oncogenic target, which imposes therapeutic constraints that are generally relevant to the translational potential of many kinases.

Objective

To study the cardioprotective properties of the activation-resistant, non-oncogenic, mutation of ILK (ILK^R211A) against experimental MI in vivo and Doxorubicin induced apoptosis in vitro and it’s relationships to stress induced heat shock proteins.

Methods/Results

The transgenic mouse heart over-expressing a point mutation in the ILK pleckstrin homology (PH) domain (Tg^R211A) exhibits a highly cardioprotective phenotype based on LAD-ligation-induced MI reduction in vivo, and on protection against doxorubicin (DOX)-induced cardiomyocyte apoptosis when overexpressed in human induced pluripotent stem cell (iPS)-derived cardiomyocytes in vitro. Intriguingly, the degree of cardioprotection seen with the ILK^R211A mutation exceeded that with the ILK^S343D mutation. Microarray and immunoprecipitation analyses revealed upregulation of expression levels and specific binding of ILK^WT, ILK^S343D and ILK^R211A to both constitutively active heat-shock protein 70 (Hsc70) and inducible Hsp70 in response to MI, and to acute ILK overexpression in iPSC-cardiomyocytes. ILK-mediated cardioprotection was shown to depend upon Hsp70 ATPase activity.

Conclusions

These findings indicate that wild type ILK and the non-oncogenic ILK^R211A mutation comprise a cardioprotective module with Hsp/c70. These results advance a novel target discovery theme in which kinase mutations can be safely engineered to enhance cardioprotective effects.