Prelamin A mediates myocardial inflammation in dilated and HIV-associated cardiomyopathies

Cardiomyopathies are complex heart muscle diseases that can be inherited or acquired. Dilated cardiomyopathy can result from mutations in LMNA, encoding the nuclear intermediate filament proteins lamin A/C. Some LMNA mutations lead to accumulation of the lamin A precursor, prelamin A, which is disease causing in a number of tissues, yet its impact upon the heart is unknown. Here, we discovered myocardial prelamin A accumulation occurred in a case of dilated cardiomyopathy, and we show that a potentially novel mouse model of cardiac-specific prelamin A accumulation exhibited a phenotype consistent with inflammatory cardiomyopathy, which we observed to be similar to HIV-associated cardiomyopathy, an acquired disease state. Numerous HIV protease therapies are known to inhibit ZMPSTE24, the enzyme responsible for prelamin A processing, and we confirmed that accumulation of prelamin A occurred in HIV+ patient cardiac biopsies. These findings (a) confirm a unifying pathological role for prelamin A common to genetic and acquired cardiomyopathies; (b) have implications for the management of HIV patients with cardiac disease, suggesting protease inhibitors should be replaced with alternative therapies (i.e., nonnucleoside reverse transcriptase inhibitors); and (c) suggest that targeting inflammation may be a useful treatment strategy for certain forms of inherited cardiomyopathy

Sex-specific cardiac remodeling in early and advanced stages of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most frequent genetic cardiac disease with a prevalence of 1:500 to 1:200. While most patients show obstructive HCM and a relatively stable clinical phenotype (stage II), a small group of patients progresses to end-stage HCM (stage IV) within a relatively brie

Preprint: Analysis of cardiomyocyte nuclei in human cardiomyopathy reveals orientation dependent defects in shape

Cardiomyopathies are progressive diseases of heart muscle often caused by mutations in genes encoding sarcomeric, cytoskeletal and nucleoskeletal proteins though in many cases the cause of disease is not identified. Whilst nucleus hypertrophy has been described, it is not known whether nucleus shape changes are a general feature of cardiomyopathy. Due to the rod-shaped nature of cardiomyocytes and their elliptical nuclei we hypothesised that orientation of analysis would be an important determinant of any changes observed between patients exhibiting primarily unexplained cardiomyopathy and control samples from non-failing donors. To investigate this we performed image analysis of cardiomyocyte nuclei in myocardial cryosections from a cohort of cardiomyopathy patients. We discovered that circularity, solidity and aspect ratio were sensitive to orientation of the myocardium and that in the transverse plane only circularity was reduced in cardiomyocyte nuclei of cardiomyopathy patients. These findings show that orientation dependent changes in nucleus shape may be a property of cardiomyopathy and with appropriate follow up studies, may prove to have mechanistic and diagnostic value

Impact of site-specific phosphorylation of protein kinase A sites Ser(23) and Ser(24) of cardiac troponin I in human cardiomyocytes

PKA-mediated phosphorylation of contractile proteins upon β-adrenergic stimulation plays an important role in the regulation of cardiac performance. Phosphorylation of the PKA sites (Se

Length-dependent activation is modulated by cardiac troponin I bisphosphorylation at Ser23 and Ser24 but not by Thr143 phosphorylation

Frank-Starling's law reflects the ability of the heart to adjust the force of its contraction to changes in ventricular filling, a property based on length-dependent myofilament activation (LDA). The threonine at amino acid 143 of cardiac troponin I (cTnI) is prerequisite for the length-dependent increase in C