On Genetics of Dilated Cardiomyopathy and Transgenic Models All Is Not Crystal Clear in Myopathic Hearts

The aB-crystallin protein, the predominant structuralprotein of the ocular lens, is a member of the smallheat shock proteins that is also expressed abundantly in the heart and skeletal muscle.1 The aB-crystallin was initially discovered in the vertebrate ocular lens and was dubbed crystallin because of its role in maintenance of lens transparency.2 It is also essential for maintenance of micro-tubular integrity in striated muscles.3 In the heart, as in the ocular lens, aB-crystallin forms soluble multimeres that function as chaperone molecules, facilitating protein folding and translocation.4 Thus, the principal function of aB-crystallin protein is to prevent unfolding of cellular proteins damaged by all forms of stress. Ischemia and oxidative stress increase the expression of aB-crystallin in the heart.5 In response to stress, intracellular kinases phosphorylate aB-crystallin,6 leading to its translocation from the cytosolic pool to Z lines and intercalated disks. Translocated aB-crystalli