Chronic Calmodulin-Kinase II Activation Drives Disease Progression in Mutation-Specific Hypertrophic Cardiomyopathy.

Autor:	Lehman SJ; Department of Physiological Sciences (S.J.L.), University of Arizona, Tucson., Tal-Grinspan L; Department of Medicine, Columbia University Medical Center, New York (L.T.-G.)., Lynn ML; Department of Medicine (M.L.L., J.C.T.), University of Arizona, Tucson., Strom J; Department of Cellular and Molecular Medicine (J.S.), University of Arizona, Tucson., Benitez GE; Department of Chemistry and Biochemistry (G.E.B.), University of Arizona, Tucson., Anderson ME; Department of Medicine, Johns Hopkins University, Baltimore, MD (M.E.A.)., Tardiff JC; Department of Medicine (M.L.L., J.C.T.), University of Arizona, Tucson.
Jazyk:	angličtina
Zdroj:	Circulation [Circulation] 2019 Mar 19; Vol. 139 (12), pp. 1517-1529.
DOI:	10.1161/CIRCULATIONAHA.118.034549
Abstrakt:	Background: Although the genetic causes of hypertrophic cardiomyopathy (HCM) are widely recognized, considerable lag in the development of targeted therapeutics has limited interventions to symptom palliation. This is in part attributable to an incomplete understanding of how point mutations trigger pathogenic remodeling. As a further complication, similar mutations within sarcomeric genes can result in differential disease severity, highlighting the need to understand the mechanism of progression at the molecular level. One pathway commonly linked to HCM progression is calcium homeostasis dysregulation, though how specific mutations disrupt calcium homeostasis remains unclear. Methods: To evaluate the effects of early intervention in calcium homeostasis, we used 2 mouse models of sarcomeric HCM (cardiac troponin T R92L and R92W) with differential myocellular calcium dysregulation and disease presentation. Two modes of intervention were tested: inhibition of the autoactivated calcium-dependent kinase (calmodulin kinase II [CaMKII]) via the AC3I peptide and diltiazem, an L-type calcium channel antagonist. Two-dimensional echocardiography was used to determine cardiac function and left ventricular remodeling, and atrial remodeling was monitored via atrial mass. Sarcoplasmic reticulum Ca 2+ ATPase activity was measured as an index of myocellular calcium handling and coupled to its regulation via the phosphorylation status of phospholamban. Results: We measured an increase in phosphorylation of CaMKII in R92W animals by 6 months of age, indicating increased autonomous activity of the kinase in these animals. Inhibition of CaMKII led to recovery of diastolic function and partially blunted atrial remodeling in R92W mice. This improved function was coupled to increased sarcoplasmic reticulum Ca 2+ ATPase activity in the R92W animals despite reduction of CaMKII activation, likely indicating improvement in myocellular calcium handling. In contrast, inhibition of CaMKII in R92L animals led to worsened myocellular calcium handling, remodeling, and function. Diltiazem-HCl arrested diastolic dysfunction progression in R92W animals only, with no improvement in cardiac remodeling in either genotype. Conclusions: We propose a highly specific, mutation-dependent role of activated CaMKII in HCM progression and a precise therapeutic target for clinical management of HCM in selected cohorts. Moreover, the mutation-specific response elicited with diltiazem highlights the necessity to understand mutation-dependent progression at a molecular level to precisely intervene in disease progression.
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu