TY - JOUR
T1 - Protein changes contributing to right ventricular cardiomyocyte diastolic dysfunction in pulmonary arterial hypertension
AU - Rain, Silvia
AU - Goncalves Bos, Denielli Silva
AU - Handoko, M. Louis
AU - Westerhof, Nico
AU - Stienen, Ger
AU - Ottenheijm, Coen
AU - Goebel, Max
AU - Dorfmüller, Peter
AU - Guignabert, Christophe
AU - Humbert, Marc
AU - Bogaard, Harm Jan
AU - Dos Remedios, Cris
AU - Saripalli, Chandra
AU - Hidalgo, Carlos G.
AU - Granzier, Henk L.
AU - Vonk-Noordegraaf, Anton
AU - Van der Velden, Jolanda
AU - De Man, Frances S.
N1 - Publisher Copyright:
© 2014 The Authors.
PY - 2014
Y1 - 2014
N2 - Background-Right ventricular (RV) diastolic function is impaired in patients with pulmonary arterial hypertension (PAH). Our previous study showed that elevated cardiomyocyte stiffness and myofilament Ca2+ sensitivity underlie diastolic dysfunction in PAH. This study investigates protein modifications contributing to cellular diastolic dysfunction in PAH. Methods and Results-RV samples from PAH patients undergoing heart-lung transplantation were compared to non-failing donors (Don). Titin stiffness contribution to RV diastolic dysfunction was determined by Western-blot analyses using antibodies to proteinkinase- A (PKA), Cα (PKCα) and Ca2+/calmoduling-dependent-kinase (CamKIIδ) titin and phospholamban (PLN) phosphorylation sites: N2B (Ser469), PEVK (Ser170 and Ser26), and PLN (Thr17), respectively. PKA and PKCα sites were significantly less phosphorylated in PAH compared with donors (P < 0.0001). To test the functional relevance of PKA-, PKCα-, and CamKIIδ-mediated titin phosphorylation, we measured the stiffness of single RV cardiomyocytes before and after kinase incubation. PKA significantly decreased PAH RV cardiomyocyte diastolic stiffness, PKCα further increased stiffness while CamKIIδ had no major effect. CamKIId activation was determined indirectly by measuring PLN Thr 17phosphorylation level. No significant changes were found between the groups. Myofilament Ca2+ sensitivity is mediated by sarcomeric troponin/(cTnI) phosphorylation. We observed increased unphosphorylated cTnI in PAH compared with donors (P < 0.05) and reduced PKA-mediated cTnI phosphorylation (Ser22/23) (P < 0.001). Finally, alterations in Ca2+-handling proteins contribute to RV diastolic dysfunction due to insufficient diastolic Ca2+ clearance. PAH SERCA2a levels and PLN phosphorylation were significantly reduced compared with donors (P < 0.05). Conclusions-Increased titin stiffness, reduced cTnI phosphorylation, and altered levels of phosphorylation of Ca2+ handling proteins contribute to RV diastolic dysfunction in PAH.
AB - Background-Right ventricular (RV) diastolic function is impaired in patients with pulmonary arterial hypertension (PAH). Our previous study showed that elevated cardiomyocyte stiffness and myofilament Ca2+ sensitivity underlie diastolic dysfunction in PAH. This study investigates protein modifications contributing to cellular diastolic dysfunction in PAH. Methods and Results-RV samples from PAH patients undergoing heart-lung transplantation were compared to non-failing donors (Don). Titin stiffness contribution to RV diastolic dysfunction was determined by Western-blot analyses using antibodies to proteinkinase- A (PKA), Cα (PKCα) and Ca2+/calmoduling-dependent-kinase (CamKIIδ) titin and phospholamban (PLN) phosphorylation sites: N2B (Ser469), PEVK (Ser170 and Ser26), and PLN (Thr17), respectively. PKA and PKCα sites were significantly less phosphorylated in PAH compared with donors (P < 0.0001). To test the functional relevance of PKA-, PKCα-, and CamKIIδ-mediated titin phosphorylation, we measured the stiffness of single RV cardiomyocytes before and after kinase incubation. PKA significantly decreased PAH RV cardiomyocyte diastolic stiffness, PKCα further increased stiffness while CamKIIδ had no major effect. CamKIId activation was determined indirectly by measuring PLN Thr 17phosphorylation level. No significant changes were found between the groups. Myofilament Ca2+ sensitivity is mediated by sarcomeric troponin/(cTnI) phosphorylation. We observed increased unphosphorylated cTnI in PAH compared with donors (P < 0.05) and reduced PKA-mediated cTnI phosphorylation (Ser22/23) (P < 0.001). Finally, alterations in Ca2+-handling proteins contribute to RV diastolic dysfunction due to insufficient diastolic Ca2+ clearance. PAH SERCA2a levels and PLN phosphorylation were significantly reduced compared with donors (P < 0.05). Conclusions-Increased titin stiffness, reduced cTnI phosphorylation, and altered levels of phosphorylation of Ca2+ handling proteins contribute to RV diastolic dysfunction in PAH.
KW - Diastole
KW - Pulmonary heart disease
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U2 - 10.1161/JAHA.113.000716
DO - 10.1161/JAHA.113.000716
M3 - Article
C2 - 24895160
AN - SCOPUS:84930396691
SN - 2047-9980
VL - 3
JO - Journal of the American Heart Association
JF - Journal of the American Heart Association
IS - 3
M1 - 000716
ER -