Phosphoproteomics distinguishes disease-specific mechanisms for human phospholamban cardiomyopathy reversible by RNA therapy

  • Signal Transduct Target Ther. 2026 May 28;11(1):199. doi: 10.1038/s41392-026-02791-5.
Frederik E Deiman  1 ,  Nils Bömer  1 ,  Pia Davidsson  2 ,  Daniela Später  2 ,  Annet N Linders  1 ,  Itamar B Dias  1 ,  Karla F Arevalo Gomez  1 ,  Antonio Esquivel Gaytan  1 ,  Jumo Zhu  1 ,  Anna Walentinsson  2 ,  Susanna Engberg  3 ,  Neil Hattersley  3 ,  Damla Etal  4 ,  Christine Ahlstrom  2 ,  Adam E Mullick  5 ,  Kenny M Hansson  2 ,  Herman H W Silljé  1 ,  Niels Grote Beverborg  1 ,  Peter van der Meer  6
Affiliations
  • 1. Department of Cardiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
  • 2. AstraZeneca, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, Gothenburg, Sweden.
  • 3. AstraZeneca, Assays, Profiling & Cell Sciences, Discovery Sciences, BioPharmaceuticals R&D, Gothenburg, Sweden.
  • 4. AstraZeneca, Translational Genomics, Centre for Genomics Research, BioPharmaceuticals R&D, Gothenburg, Sweden.
  • 5. Ionis Pharmaceuticals, Carlsbad, CA, USA.
  • 6. Department of Cardiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands. [email protected].
PMID: 42204136 DOI: 10.1038/s41392-026-02791-5
Abstract

Phospholamban (PLN) p.Arg14del (R14Δ/+, also known as R14del) is a pathogenic variant that causes inherited cardiomyopathy. RNA therapy improves cardiac function and survival in murine PLN R14Δ/+. However, the molecular disease mechanisms and potential therapeutic effects of RNA therapy in the human setting remain poorly defined. Proteomic and phosphoproteomic profiling was performed on cardiac tissue from R14Δ/+ patients (N = 6) and compared to Other causes of dilated cardiomyopathy (DCM; N = 10). Findings were validated in CRISPR-Cas9-engineered R14Δ/+ induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and isogenic controls. To assess reversibility, PLN-targeted RNA therapy using Antisense Oligonucleotides was applied to iPSC-CMs. Proteomics revealed enrichment of fibrotic pathways, while phosphoproteomics highlighted altered actomyosin structural organization uniquely distinguishing R14Δ/+ from Other DCM. This phosphoproteomic profile was recapitulated in R14Δ/+ iPSC-CMs. RNA therapy concentration-dependently reduced PLN expression and modified the disease-specific phosphorylation profile. Twenty-eight phosphorylation sites were consistently altered across patient tissue and iPSC-CMs; twenty-two were reversed by RNA therapy and were enriched for cadherin- and actin-binding functions, implicating cytoskeletal remodeling. PLN/LC3 protein aggregates, a hallmark of PLN cardiomyopathy, were reduced after RNA therapy. Functionally, R14Δ/+ cardiomyocytes exhibited accelerated calcium handling and contractile kinetics, which increased further upon RNA therapy. Human PLN R14Δ/+ cardiomyopathy is characterized by a distinct phosphoproteomic signature involving cytoskeletal and contractile machinery. PLN-targeted RNA therapy reduced PLN expression, partially normalized these alterations, diminished protein aggregation, and enhanced calcium handling and contractile performance. These findings clarify the molecular mechanisms underlying R14Δ/+ pathogenesis and support RNA therapy as a promising therapeutic strategy for PLN cardiomyopathy.

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