PITX2 deficiency leads to atrial mitochondrial dysfunction

Jasmeet S Reyat; Laura C Sommerfeld; Molly O'Reilly; Victor R Cardoso; Ellen Thiemann; Abdullah O Khan; Christopher O'Shea; Sönke Harder; Christian Müller; Jonathan Barlow; Rachel J Stapley; Winnie Chua; S Nashitha Kabir; Olivia Grech; Oliver Hummel; Norbert Hübner; Stefan Kääb; Lluis Mont; Stéphane N Hatem; Joris Winters; Stef Zeemering; Neil V Morgan; Julie Rayes; Katja Gehmlich; Monika Stoll; Theresa Brand; Michaela Schweizer; Angelika Piasecki; Ulrich Schotten; Georgios V Gkoutos; Kristina Lorenz; Friederike Cuello; Paulus Kirchhof; Larissa Fabritz

doi:10.1093/cvr/cvae169

PITX2 deficiency leads to atrial mitochondrial dysfunction

Cardiovasc Res. 2024 Aug 12:cvae169. doi: 10.1093/cvr/cvae169. Online ahead of print.

Authors

Jasmeet S Reyat^{1

2}, Laura C Sommerfeld^{1

3

4

5}, Molly O'Reilly¹, Victor R Cardoso^{1

6}, Ellen Thiemann^{3

4

7}, Abdullah O Khan¹, Christopher O'Shea¹, Sönke Harder⁸, Christian Müller⁹, Jonathan Barlow¹⁰, Rachel J Stapley¹, Winnie Chua¹, S Nashitha Kabir¹, Olivia Grech¹, Oliver Hummel¹¹, Norbert Hübner^{12

13}, Stefan Kääb^{14

15}, Lluis Mont^{16

17}, Stéphane N Hatem¹⁸, Joris Winters¹⁹, Stef Zeemering¹⁹, Neil V Morgan¹, Julie Rayes¹, Katja Gehmlich¹, Monika Stoll^{20

21}, Theresa Brand²², Michaela Schweizer²³, Angelika Piasecki⁷, Ulrich Schotten¹⁹, Georgios V Gkoutos⁶, Kristina Lorenz^{22

24}, Friederike Cuello^{4

7}, Paulus Kirchhof^{1

3

4}, Larissa Fabritz^{1

3

4

5}

Affiliations

¹ Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Wolfson Drive, Birmingham, UK.
² Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
³ Department of Cardiology, University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany.
⁴ DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Germany.
⁵ University Center of Cardiovascular Sciences, University Medical Center Hamburg-Eppendorf, Germany.
⁶ Institute of Cancer Genomics, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
⁷ Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
⁸ Institut für Klinische Chemie und Laboratoriumsmedizin, Massenspektrometrische Proteomanalytik, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
⁹ UKE Bioinformatics Core; University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
¹⁰ Cellular Health and Metabolism Facility, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK.
¹¹ Max Delbrück Centrum for Molecular Medicine, Berlin, Germany, Charite - Universitätsmedizin Berlin, German, and German Center for Cardiovascular Research (DZHK), partner site Berlin.
¹² Charite - Universitätsmedizin Berlin, Germany.
¹³ German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Germany.
¹⁴ Department of Medicine I, University Hospital Munich, Ludwig Maximilian University of Munich (LMU), Munich, Germany.
¹⁵ German Centre for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, Munich, Germany.
¹⁶ Hospital Clínic, Universitat de Barcelona, Catalonia, Spain and Institut de Recerca Biomèdica, August Pi- i Sunyer, Barcelona, Catalonia, Spain.
¹⁷ Centro Investigación Biomedica en Red Cardiovascular, Madrid, Spain.
¹⁸ INSERM UMRS1166, ICAN - Institute of Cardiometabolism and Nutrition, Sorbonne University, Institute of Cardiology, Pitié-Salpêtrière Hospital, Paris, France.
¹⁹ Cardiovascular Research Institute Maastricht, Department of Physiology, Maastricht University, Maastricht, The Netherlands.
²⁰ Institute of Human Genetics, Genetic Epidemiology, WWU Münster, Germany.
²¹ Cardiovascular Research Institute Maastricht, Genetic Epidemiology and Statistical Genetics, Maastricht University, Maastricht, Netherlands.
²² Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany.
²³ Department of Morphology and Electron Microscopy, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany.
²⁴ Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany.

PMID: 39129206
DOI: 10.1093/cvr/cvae169

Abstract

Aim: Reduced left atrial PITX2 is associated with atrial cardiomyopathy and atrial fibrillation. PITX2 is restricted to left atrial cardiomyocytes in the adult heart. The links between PITX2 deficiency, atrial cardiomyopathy and atrial fibrillation are not fully understood.

Methods and results: To identify mechanisms linking PITX2 deficiency to atrial fibrillation, we generated and characterized PITX2-deficient human atrial cardiomyocytes derived from human induced pluripotent stem cells (hiPSC) and their controls. PITX2-deficient hiPSC-derived atrial cardiomyocytes showed shorter and disorganised sarcomeres and increased mononucleation. Electron microscopy found an increased number of smaller mitochondria compared to the control. Mitochondrial protein expression was altered in PITX2-deficient hiPSC-derived atrial cardiomyocytes. Single-nuclear RNA-sequencing found differences in cellular respiration pathways and differentially expressed mitochondrial and ion channel genes in PITX2-deficient hiPSC-derived atrial cardiomyocytes. PITX2 repression in hiPSC-derived atrial cardiomyocytes replicated dysregulation of cellular respiration. Mitochondrial respiration was shifted to increased glycolysis in PITX2-deficient hiPSC-derived atrial cardiomyocytes. PITX2-deficient human hiPSC-derived atrial cardiomyocytes showed higher spontaneous beating rates. Action potential duration was more variable with an overall prolongation of early repolarization, consistent with metabolic defects. Gene expression analyses confirmed changes in mitochondrial genes in left atria from 42 patients with atrial fibrillation compared to 43 patients in sinus rhythm. Dysregulation of left atrial mitochondrial (COX7C) and metabolic (FOXO1) genes was associated with PITX2 expression in human left atria.

Conclusions: In summary, PITX2 deficiency causes mitochondrial dysfunction and a metabolic shift to glycolysis in human atrial cardiomyocytes. PITX2-dependent metabolic changes can contribute to the structural and functional defects found in PITX2-deficient atria.

Keywords: PITX2; atrial fibrillation; human heart tissue; human induced pluripotent stem cells; metabolic shift; mitochondrial dysfunction.