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An FDA-approved drug structurally and phenotypically corrects the K210del mutation in genetic cardiomyopathy models
Ping Wang1, Mahmoud Salama Ahmed1,2, Ngoc Uyen Nhi Nguyen1
1Division of Cardiology, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Abstract:
Dilated cardiomyopathy (DCM) due to genetic disorders results in decreased myocardial contractility, leading to high morbidity and mortality rates. There are several therapeutic challenges in treating DCM, including poor understanding of the underlying mechanism of impaired myocardial contractility and the difficulty of developing targeted therapies to reverse mutation-specific pathologies. In this report, we focused on K210del, a DCM-causing mutation, due to 3-nucleotide deletion of sarcomeric troponin T (TnnT), resulting in loss of Lysine210. We resolved the crystal structure of the troponin complex carrying the K210del mutation. K210del induced an allosteric shift in the troponin complex resulting in distortion of activation Ca2+-binding domain of troponin C (TnnC) at S69, resulting in calcium discoordination. Next, we adopted a structure-based drug repurposing approach to identify bisphosphonate risedronate as a potential structural corrector for the mutant troponin complex. Cocrystallization of risedronate with the mutant troponin complex restored the normal configuration of S69 and calcium coordination. Risedronate normalized force generation in K210del patient-induced pluripotent stem cell-derived (iPSC-derived) cardiomyocytes and improved calcium sensitivity in skinned papillary muscles isolated from K210del mice. Systemic administration of risedronate to K210del mice normalized left ventricular ejection fraction. Collectively, these results identify the structural basis for decreased calcium sensitivity in K210del and highlight structural and phenotypic correction as a potential therapeutic strategy in genetic cardiomyopathies.
Insights
Genetic dilated cardiomyopathy (DCM) impairs heart muscle contraction. Researchers found risedronate can correct a specific mutation (K210del) in troponin T, restoring heart function in preclinical models.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Genetic Medicine
Background:
- Dilated cardiomyopathy (DCM) is a severe genetic heart condition characterized by reduced myocardial contractility.
- Current therapeutic strategies for DCM face challenges due to incomplete understanding of disease mechanisms and difficulties in developing mutation-specific treatments.
Purpose of the Study:
- To elucidate the structural mechanism underlying the K210del mutation in sarcomeric troponin T (TnnT) that causes DCM.
- To identify potential therapeutic agents capable of correcting the structural and functional defects associated with the K210del mutation.
Main Methods:
- Crystal structure determination of the K210del mutant troponin complex.
- Structure-based drug repurposing to identify small molecules that can restore normal protein conformation.
- Functional assessment using patient-derived induced pluripotent stem cell (iPSC)-derived cardiomyocytes and ex vivo muscle preparations from K210del mice.
- In vivo efficacy studies in K210del mouse models.
Main Results:
- The K210del mutation causes an allosteric shift in the troponin complex, distorting the troponin C (TnnC) calcium-binding site and impairing calcium coordination.
- Risedronate was identified as a structural corrector, restoring normal S69 configuration and calcium coordination upon cocrystallization with the mutant troponin complex.
- Risedronate normalized cardiomyocyte contractility, improved calcium sensitivity in muscle tissues, and restored cardiac function (left ventricular ejection fraction) in K210del mice.
Conclusions:
- The study reveals the precise structural defect leading to decreased calcium sensitivity in K210del DCM.
- Structural and phenotypic correction using risedronate represents a promising therapeutic avenue for genetic cardiomyopathies like K210del DCM.
