Takotsubo syndrome (TTS) is an acute stress-induced cardiomyopathy characterized by reversible left ventricular dysfunction and significant acute morbidity and mortality. The source study evaluated protein phosphatase 2A (PP2A) activity across disease-relevant settings and reports that PP2A activity was markedly reduced in cardiac tissues from mice with isoprenaline-induced TTS as well as in isoprenaline-treated cardiomyocytes. These observations motivated experimental interrogation of PP2A as a putative mediator between catecholamine stress and myocardial injury.
The investigation combined analysis of public multi-omics datasets from stress cardiomyopathy and experimental models of TTS with in vitro and in vivo experiments. Cardiomyocytes were treated with human TTS plasma in cell-based assays, and isoprenaline was used to induce TTS-like injury in animal models. The authors used both genetic manipulation and pharmacological agents to modulate PP2A activity in cardiomyocytes and in mice. To explore downstream pathways and cellular phenotypes, RNA sequencing, assessments of stress-responsive iron handling, measures of mitochondrial function, and standard cardiac phenotyping were performed in vitro and in vivo.
Genetic or pharmacological suppression of PP2A activity exacerbated catecholamine-induced cardiac dysfunction and increased myocardial injury in the models studied. In cardiomyocytes treated with isoprenaline or TTS plasma, PP2A inactivation coincided with activation of stress signaling pathways and disturbances in iron homeostasis. These perturbations correlated with mitochondrial dysfunction and cell death phenotypes consistent with regulated necrotic pathways.
The authors report that pharmacological activation of PP2A using an orally bioavailable small-molecule activator strongly mitigated myocardial damage and improved cardiac function in TTS models. Activation of PP2A reversed many of the deleterious cellular responses observed with PP2A inactivation in the experimental systems, suggesting that short-term restoration of PP2A activity during acute catecholamine stress can be cardioprotective in these preclinical models.
Mechanistic studies indicated that PP2A deficiency promoted activation of the JNK-MAPK signaling pathway and dysregulated stress-responsive iron-handling pathways. These changes led to ferritinophagy-dependent iron release and subsequent ferroptosis, accompanied by mitochondrial dysfunction in cardiomyocytes. The sequence of events described in the source positions PP2A inactivation upstream of JNK activation and iron-mediated oxidative damage, providing a molecular framework that connects catecholamine stress to the observed myocardial injury.
To test the downstream importance of JNK signaling, the investigators used pharmacologic JNK inhibition in PP2A-deficient settings. JNK inhibition effectively rescued myocardial injury caused by PP2A deficiency in two animal models of TTS and in cardiomyocytes. These rescue experiments support the interpretation that the PP2A–JNK axis is a critical mediator of the ferroptosis and mitochondrial injury observed after catecholamine stress in the studied models.
The study identifies PP2A inactivation as a key molecular event that links catecholamine stress to myocardial injury in TTS. In preclinical models, restoring PP2A activity or inhibiting downstream JNK signaling attenuated ferritinophagy-dependent stress responses and improved mitochondrial function, reducing myocardial damage. These findings suggest the PP2A–JNK axis may represent a target for short-term therapeutic intervention during the acute phase of TTS. The reported orally bioavailable PP2A activator produced robust protective effects in the models used, indicating potential translatability pending further validation.
This work is presented as a preprint and has not been certified by peer review. The source provides experimental results from multi-omics analyses, cell-based assays, and animal models, but quantitative details, dosing regimens, safety data, and longer-term outcomes are reported in the preprint and are not reproduced in full here. Potential conflicts of interest declared in the source include consulting fees and equity stakes for some authors related to biotherapeutic companies. Further peer-reviewed studies are required to confirm reproducibility, safety, and clinical applicability of targeting PP2A or JNK in Takotsubo syndrome.