Journal of molecular and cellular cardiology · 2025
Catecholaminergic stress results in signs of heart failure in PP2A-PR72 overexpressor mice.
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Pauls Paul, Fabritz Larissa, Herting Julius R, Johann Amanda, König Jule H, Schulte Jan S, Seidl Matthias D, Soppa Carolina E, Kirchhefer Uwe
Аннотация
BACKGROUND: It is unclear whether the increase in protein expression of PP2A regulatory subunit PR72 seen in human heart failure represents a primary compensatory mechanism or the final reaction to contractile decompensation. To address this question, we have explored the effects of chronic catecholaminergic stress in a transgenic (TG) mouse model with heart-specific overexpression of PR72 that exhibits hypercontractility at basal conditions.
METHODS: Mice were treated with isoprenaline (ISO) or NaCl for 7 days using osmotic minipumps. Hearts or isolated cardiomyocytes from the animals were functionally examined.
RESULTS: We could show (i) that PR72 expression is not only increased after chronic ISO stimulation but also in other different stress and insufficiency models. In TG mice, 7 days of ISO treatment led to (ii) increased hypertrophy, pulmonary edema, more fibrosis, and higher ACTA1 gene expression compared to wild-type (WT) mice. These effects were accompanied by (iii) a decrease in myocellular contractility and prolonged relaxation. Ca2+ transients (iv) showed correspondingly delayed decay kinetics in TG versus WT, while (v) the reduction of L-type calcium peak current by ISO treatment was less pronounced in TG cells. The decrease in RyR2 phosphorylation in TG (vi) supports a deterioration in contractility due to chronic ISO treatment in TG.
CONCLUSION: Our results indicate that the upregulation of PP2A-PR72 in various stress and heart failure models has a long-term effect, perpetuating the molecular and functional detrimental cardiac changes, if it does not have a triggering effect.
METHODS: Mice were treated with isoprenaline (ISO) or NaCl for 7 days using osmotic minipumps. Hearts or isolated cardiomyocytes from the animals were functionally examined.
RESULTS: We could show (i) that PR72 expression is not only increased after chronic ISO stimulation but also in other different stress and insufficiency models. In TG mice, 7 days of ISO treatment led to (ii) increased hypertrophy, pulmonary edema, more fibrosis, and higher ACTA1 gene expression compared to wild-type (WT) mice. These effects were accompanied by (iii) a decrease in myocellular contractility and prolonged relaxation. Ca2+ transients (iv) showed correspondingly delayed decay kinetics in TG versus WT, while (v) the reduction of L-type calcium peak current by ISO treatment was less pronounced in TG cells. The decrease in RyR2 phosphorylation in TG (vi) supports a deterioration in contractility due to chronic ISO treatment in TG.
CONCLUSION: Our results indicate that the upregulation of PP2A-PR72 in various stress and heart failure models has a long-term effect, perpetuating the molecular and functional detrimental cardiac changes, if it does not have a triggering effect.