Endoplasmic reticulum stress induces different molecular structural alterations in human dilated and ischemic cardiomyopathy.

BACKGROUND: The endoplasmic reticulum (ER) is a multifunctional organelle responsible for the synthesis and folding of proteins as well as for signalling and calcium storage, that has been linked to the contraction-relaxation process. Perturbations of its homeostasis activate a stress response in diseases such as heart failure (HF). To elucidate the alterations in ER molecular components, we analyze the levels of ER stress and structure proteins in human dilated (DCM) and ischemic (ICM) cardiomyopathies, and its relationship with patient's functional status. METHODS AND RESULTS: We examined 52 explanted human hearts from DCM (n = 21) and ICM (n = 21) subjects and 10 non-failing hearts as controls. Our results showed specific changes in stress (IRE1, p<0.05; p-IRE1, p<0.05) and structural (Reticulon 1, p<0.01) protein levels. The stress proteins GRP78, XBP1 and ATF6 as well as the structural proteins RRBP1, kinectin, and Nogo A and B, were upregulated in both DCM and ICM patients. Immunofluorescence results were concordant with quantified Western blot levels. Moreover, we show a novel relationship between stress and structural proteins. RRBP1, involved in procollagen synthesis and remodeling, was related with left ventricular function. CONCLUSIONS: In the present study, we report the existence of alterations in ER stress response and shaping proteins. We show a plausible effect of the ER stress on ER structure in a suitable sample of DCM and ICM subjects. Patients with higher values of RRBP1 had worse left ventricular function

Clinical characteristics of patients according to HF etiology.

<p>DCM, dilated cardiomyopathy; ICM, ischemic cardiomyopathy; NYHA class, New York Heart Association class; BMI, body mass index; EF, ejection fraction; FS, fractional shortening; LVESD, left ventricular end-systolic diameter; LVEDD, left ventricular end-diastolic diameter.</p><p>*<i>p</i><0.05;</p><p>**<i>p</i><0.01.</p><p>Clinical characteristics of patients according to HF etiology.</p

Western blot and immunofluorescence studies of Nogo A and B according to heart failure etiology and compared to a control (CNT) group.

<p>(<b>A</b>) Protein levels of Nogo A. (<b>B</b>) Protein levels of Nogo B. (<b>C</b>) Immunofluorescence of Nogo A+B. The values are normalized to GAPDH and finally to the CNT group. Values from the CNT group are set to 100. The data are expressed as means ± standard error of the mean (SEM) in optical density, arbitrary units (AU), of two independent experiments. DCM, dilated cardiomyopathy, ICM, ischemic cardiomyopathy. *<i>p</i><0.01, **<i>p</i><0.001 <i>vs.</i> the CNT group. #<i>p</i><0.05 DCM <i>vs.</i> the ICM group. The bar represents 10 µm.</p

Western blot and immunofluorescence studies of cell distribution of some endoplasmic reticulum structural proteins in human left ventricular cardiomyocytes according to heart failure etiology and compared to a control (CNT) group.

<p>(<b>A</b>) Ribosomal receptor-binding protein (RRBP1) levels. (<b>B</b>) Immunofluorescence of RRBP1 protein. (<b>C</b>) Kinectin protein levels. (<b>D</b>) Immunofluorescence of kinectin. The values are normalized to GAPDH and finally to the CNT group. Values from the CNT group are set to 100. The data are expressed as means ± standard error of the mean (SEM) in optical density, arbitrary units (AU), of two independent experiments. *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001 <i>vs.</i> the CNT group. The bar represents 10 µm.</p

Scatter plots of correlation between RRBP1 and ejection fraction (EF) in dilated and ischemic cardiomyopathy human hearts.

<p>The values of RRBP1 are normalized to GAPDH.</p

Western blot analysis of structural proteins of the endoplasmic reticulum in dilated (DCM) and ischemic (ICM) cardiomyopathy and control (CNT) groups.

<p>(<b>A</b>) Cytoskeleton-associated protein 4 (CKAP4). (<b>B</b>) Reticulon 1. The values are normalized to GAPDH and finally to the CNT group. Values from the CNT group are set to 100. The data are expressed as means ± standard error of the mean (SEM) in optical density, arbitrary units (AU), of two independent experiments. *<i>p</i><0.01 <i>vs.</i> the CNT group. #<i>p</i><0.01 DCM <i>vs.</i> the ICM group.</p

Mapping the human genetic architecture of COVID-19

The genetic make-up of an individual contributes to the susceptibility and response to viral infection. Although environmental, clinical and social factors have a role in the chance of exposure to SARS-CoV-2 and the severity of COVID-191,2, host genetics may also be important. Identifying host-specific genetic factors may reveal biological mechanisms of therapeutic relevance and clarify causal relationships of modifiable environmental risk factors for SARS-CoV-2 infection and outcomes. We formed a global network of researchers to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity. Here we describe the results of three genome-wide association meta-analyses that consist of up to 49,562 patients with COVID-19 from 46 studies across 19 countries. We report 13 genome-wide significant loci that are associated with SARS-CoV-2 infection or severe manifestations of COVID-19. Several of these loci correspond to previously documented associations to lung or autoimmune and inflammatory diseases3–7. They also represent potentially actionable mechanisms in response to infection. Mendelian randomization analyses support a causal role for smoking and body-mass index for severe COVID-19 although not for type II diabetes. The identification of novel host genetic factors associated with COVID-19 was made possible by the community of human genetics researchers coming together to prioritize the sharing of data, results, resources and analytical frameworks. This working model of international collaboration underscores what is possible for future genetic discoveries in emerging pandemics, or indeed for any complex human disease

Mapping the human genetic architecture of COVID-19

The genetic make-up of an individual contributes to the susceptibility and response to viral infection. Although environmental, clinical and social factors have a role in the chance of exposure to SARS-CoV-2 and the severity of COVID-191,2, host genetics may also be important. Identifying host-specific genetic factors may reveal biological mechanisms of therapeutic relevance and clarify causal relationships of modifiable environmental risk factors for SARS-CoV-2 infection and outcomes. We formed a global network of researchers to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity. Here we describe the results of three genome-wide association meta-analyses that consist of up to 49,562 patients with COVID-19 from 46 studies across 19 countries. We report 13 genome-wide significant loci that are associated with SARS-CoV-2 infection or severe manifestations of COVID-19. Several of these loci correspond to previously documented associations to lung or autoimmune and inflammatory diseases3,4,5,6,7. They also represent potentially actionable mechanisms in response to infection. Mendelian randomization analyses support a causal role for smoking and body-mass index for severe COVID-19 although not for type II diabetes. The identification of novel host genetic factors associated with COVID-19 was made possible by the community of human genetics researchers coming together to prioritize the sharing of data, results, resources and analytical frameworks. This working model of international collaboration underscores what is possible for future genetic discoveries in emerging pandemics, or indeed for any complex human disease