Perinuclear damage from nuclear envelope deterioration elicits stress responses that contribute to <i>LMNA</i> cardiomyopathy.

Abstract

Mutations in the <i>LMNA</i> gene encoding lamins A/C cause an array of tissue-selective diseases, with the heart being the most commonly affected organ. Despite progress in understanding the perturbations emanating from <i>LMNA</i> mutations, an integrative understanding of the pathogenesis underlying cardiac dysfunction remains elusive. Using a novel conditional deletion model capable of translatome profiling, we observed that cardiomyocyte-specific <i>Lmna</i> deletion in adult mice led to rapid cardiomyopathy with pathological remodeling. Before cardiac dysfunction, <i>Lmna</i>-deleted cardiomyocytes displayed nuclear abnormalities, Golgi dilation/fragmentation, and CREB3-mediated stress activation. Translatome profiling identified MED25 activation, a transcriptional cofactor that regulates Golgi stress. Autophagy is disrupted in the hearts of these mice, which can be recapitulated by disrupting the Golgi. Systemic administration of modulators of autophagy or ER stress significantly delayed cardiac dysfunction and prolonged survival. These studies support a hypothesis wherein stress responses emanating from the perinuclear space contribute to the <i>LMNA</i> cardiomyopathy development.