Mechanisms of Pathogenicity of Hypertrophic Cardiomyopathy-Associated Troponin T (TNNT2) Variant R278C+/- During Development

Sanam Shafaattalab; Alison Y Li; Farah Jayousi; Yasaman Maaref; Saif Dababneh; Homa Hamledari; Dina Hosseini Baygi; Tiffany Barszczewski; Balwinder Ruprai; Shayan Jannati; Raghu Nagalingam; Austin M Cool; Paulina Langa; Mu Chiao; Thomas Roston; R John Solaro; Shubhayan Sanatani; Christopher Toepfer; Steffen Lindert; Philipp Lange; Glen F Tibbits

doi:10.1101/2023.06.06.542948

Mechanisms of Pathogenicity of Hypertrophic Cardiomyopathy-Associated Troponin T (TNNT2) Variant R278C^+/- During Development

bioRxiv [Preprint]. 2023 Aug 13:2023.06.06.542948. doi: 10.1101/2023.06.06.542948.

Authors

Sanam Shafaattalab^{1

2}, Alison Y Li^{1

2}, Farah Jayousi^{1

2}, Yasaman Maaref^{1

2}, Saif Dababneh^{1

3}, Homa Hamledari^{1

2}, Dina Hosseini Baygi^{1

2}, Tiffany Barszczewski^{1

2}, Balwinder Ruprai^{1

2}, Shayan Jannati^{1

4}, Raghu Nagalingam^{1

2}, Austin M Cool⁵, Paulina Langa⁶, Mu Chiao⁴, Thomas Roston⁷, R John Solaro⁶, Shubhayan Sanatani¹, Christopher Toepfer⁸, Steffen Lindert⁴, Philipp Lange^{9

10}, Glen F Tibbits^{1

2

11

12}

Affiliations

¹ Cellular and Regenerative Medicine Centre, BC Children's Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada.
² Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
³ Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
⁴ Mechanical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
⁵ Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA.
⁶ Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA.
⁷ Division of Cardiology and Centre for Cardiovascular Innovation, The University of British Columbia 1081 Burrard Street, Level 4 Cardiology Vancouver, BC, V6Z 1Y6, Canada.
⁸ University of Oxford, Oxford, UK.
⁹ Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC.
¹⁰ Michael Cuccione Childhood Cancer Research Program, BC Children's Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada.
¹¹ Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
¹² School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.

Abstract

Hypertrophic cardiomyopathy (HCM) is one of the most common heritable cardiovascular diseases and variants of TNNT2 (cardiac troponin T) are linked to increased risk of sudden cardiac arrest despite causing limited hypertrophy. In this study, a TNNT2 variant, R278C^+/-, was generated in both human cardiac recombinant/reconstituted thin filaments (hcRTF) and human- induced pluripotent stem cells (hiPSCs) to investigate the mechanisms by which the R278C^+/- variant affects cardiomyocytes at the proteomic and functional levels. The results of proteomics analysis showed a significant upregulation of markers of cardiac hypertrophy and remodeling in R278C^+/- vs. the isogenic control. Functional measurements showed that R278C^+/- variant enhances the myofilament sensitivity to Ca²⁺, increases the kinetics of contraction, and causes arrhythmia at frequencies >75 bpm. This study uniquely shows the profound impact of the TNNT2 R278C^+/- variant on the cardiomyocyte proteomic profile, cardiac electrical and contractile function in the early stages of cardiac development.

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