Cardiomyocyte damage control in heart failure and the role of the sarcolemma.

The cardiomyocyte plasma membrane, termed the sarcolemma, is fundamental for regulating a myriad of cellular processes. For example, the structural integrity of the cardiomyocyte sarcolemma is essential for mediating cardiac contraction by forming microdomains such as the t-tubular network, caveolae and the intercalated disc. Significantly, remodelling of these sarcolemma microdomains is a key feature in the development and progression of heart failure (HF). However, despite extensive characterisation of the associated molecular and ultrastructural events there is a lack of clarity surrounding the mechanisms driving adverse morphological rearrangements. The sarcolemma also provides protection, and is the cell's first line of defence, against external stresses such as oxygen and nutrient deprivation, inflammation and oxidative stress with a loss of sarcolemma viability shown to be a key step in cell death via necrosis. Significantly, cumulative cell death is also a feature of HF, and is linked to disease progression and loss of cardiac function. Herein, we will review the link between structural and molecular remodelling of the sarcolemma associated with the progression of HF, specifically considering the evidence for: (i) Whether intrinsic, evolutionary conserved, plasma membrane injury-repair mechanisms are in operation in the heart, and (ii) if deficits in key 'wound-healing' proteins (annexins, dysferlin, EHD2 and MG53) may play a yet to be fully appreciated role in triggering sarcolemma microdomain remodelling and/or necrosis. Cardiomyocytes are terminally differentiated with very limited regenerative capability and therefore preserving cell viability and cardiac function is crucially important. This review presents a novel perspective on sarcolemma remodelling by considering whether targeting proteins that regulate sarcolemma injury-repair may hold promise for developing new strategies to attenuate HF progression.