Dalma Kellermayer, Cristina M Șulea, Hedvig Tordai, Kálmán Benke, Miklós Pólos, Bence Ágg, Roland Stengl, Máté Csonka, Tamás Radovits, Béla Merkely, Zoltán Szabolcs, Miklós Kellermayer, Balázs Kiss
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引用次数: 0
Abstract
Marfan syndrome (MFS) is an autosomal dominant disease caused by mutations in the gene (FBN1) of fibrillin-1, a major determinant of the extracellular matrix (ECM). Functional impairment in the cardiac left ventricle (LV) of these patients is usually a consequence of aortic valve disease. However, LV passive stiffness may also be affected by chronic changes in mechanical load and ECM dysfunction. Passive stiffness is determined by the giant sarcomeric protein titin that has two main cardiac splice isoforms: the shorter and stiffer N2B and the longer and more compliant N2BA. Their ratio is thought to reflect myocardial response to pathologies. Whether this ratio and titin's sarcomeric layout is altered in MFS is currently unknown. Here, we studied LV samples from MFS patients carrying FBN1 mutation, collected during aortic root replacement surgery. We found that the N2BA:N2B titin ratio was elevated, indicating a shift toward the more compliant isoform. However, there were no alterations in the total titin content compared with healthy humans based on literature data. Additionally, while the gross sarcomeric structure was unaltered, the M-band was more extended in the MFS sarcomere. We propose that the elevated N2BA:N2B titin ratio reflects a general adaptation mechanism to the increased volume overload resulting from the valvular disease and the direct ECM disturbances so as to reduce myocardial passive stiffness and maintain diastolic function in MFS.
期刊介绍:
General physiology is the study of biological mechanisms through analytical investigations, which decipher the molecular and cellular mechanisms underlying biological function at all levels of organization.
The mission of Journal of General Physiology (JGP) is to publish mechanistic and quantitative molecular and cellular physiology of the highest quality, to provide a best-in-class author experience, and to nurture future generations of independent researchers. The major emphasis is on physiological problems at the cellular and molecular level.