E Männer (1), MJ Cambra (1), H Heymer (1), M Corsten (1), K Zeppenfeld (2), C Kupatt (1), A Bähr (1), N Klymiuk (1)

1. Department of Internal Medicine I, Klinikum rechts der Isar, TU Munich, Germany; 2. Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands

Introduction:
Phospholamban (PLN) is a small protein regulating intracellular Ca²⁺ in cardiomyocytes. The R14del mutation in the PLN gene disrupts Ca²⁺ homeostasis and is associated with dilated and arrhythmogenic cardiomyopathy. To explore disease mechanisms and potential therapeutic targets, a transgenic pig model carrying the R14del mutation was developed. To gain insight into the molecular characteristics of cellular stress associated with Ca²⁺ misregulation, we compared a panel of stress markers to electrophysiological examination.

Methods:
Twelve pigs aged 5-7 months (5 WT, 7 PLN-R14del) were studied. Electrophysiological mapping was performed, and cryo-conserved heart tissue samples were processed for qPCR-based analysis. A stress marker panel of 36 primers was designed and optimized to target markers of cytokines, inflammation, oxidative stress, cell death, and general stress indicators (e. g. Il-1a, CD45, CAT, BAX, DDIT3)

Results:
Mapping data appear to suggest the possibility of localized electrophysiological abnormalities in PLN-R14del heart. For qPCR-based analysis, all markers were found to be expressed at Cq level of 17-33, allowing for precise quantification, while transcript levels of PLN-WT and PLN-R14del alleles were higher (Cq approx. 17-19; lower Cq = higher expression). Preliminary data for stress markers indicated small variability of the respective markers between samples and between individuals.

Outlook:
Next steps will be the completion of the qPCR-based stress marker panel for the entire experimental cohort. Future steps will include a more comprehensive comparison of expression profiles with electrophysiological and histological data, proteomics profiles and scRNAseq analyses in the examined age group as well as in older animals.