Paclitaxel mitigates structural alterations and cardiac conduction system defects in a mouse model of Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is an ultrarare laminopathy caused by expression of progerin, a lamin A variant, also present at low levels in non-HGPS individuals. HGPS patients age and die prematurely, predominantly from cardiovascular complications. Progerin-induced cardiac repolarization defects have been described previously, although the underlying mechanisms are unknown. We conducted studies in heart tissue from progerin-expressing LmnaG609G/G609G (G609G) mice, including microscopy, intracellular calcium dynamics, patch-clamping, in vivo magnetic resonance imaging, and electrocardiography. G609G mouse cardiomyocytes showed tubulin-cytoskeleton disorganization, t-tubular system disruption, sarcomere shortening, altered excitation-contraction coupling, and reductions in ventricular thickening and cardiac index. G609G mice exhibited severe bradycardia, and significant alterations of atrio-ventricular conduction and repolarization. Most importantly, 50% of G609G mice had altered heart rate variability, and sinoatrial block, both significant signs of premature cardiac aging. G609G cardiomyocytes had electrophysiological alterations, which resulted in an elevated action potential plateau and early afterdepolarization bursting, reflecting slower sodium current inactivation and long Ca+2 transient duration, which may also help explain the mild QT prolongation in some HGPS patients. Chronic treatment with low-dose paclitaxel ameliorated structural and functional alterations in G609G hearts. Our results demonstrate that tubulin-cytoskeleton disorganization in progerin-expressing cardiomyocytes causes structural, cardiac conduction, and excitation-contraction coupling defects, all of which can be partially corrected by chronic treatment with low dose paclitaxel.Work in V.A.’s laboratory is supported by grants from the Spanish Ministerio de Ciencia e Innovacio´n (MCIN) (SAF2016-79490-R, PID2019-108489RBI00) and the Instituto de Salud Carlos III (ISCIII) (AC17/00067) with cofunding from the European Regional Development Fund/Fondo Europeo de Desarrollo Regional (ERDF/FEDER, ‘Una manera de hacer Europa’), and the Progeria Research Foundation (Award PRF 2019–77). Work in J.J.’s laboratory is supported by the National Heart, Lung, and Blood Institute (R01 Grant HL122352), a CNIC ‘Severo Ochoa’ intramural competitive grant, and Fondos FEDER, Madrid, Spain. Work in D.F.-R.’s laboratory is supported by the Spanish MCIN (SAF2016-80324-R) and the ISCIII (AC17/00053). The CNIC is supported by the MCIN, the ISCIII, and the Pro CNIC Foundation.S