Enhanced nuclear localization of phosphorylated MLKL predicts adverse events in patients with dilated cardiomyopathy

Abstract

Aims The role of necroptosis in dilated cardiomyopathy (DCM) remains unclear. Here, we examined whether phosphorylation of mixed lineage kinase domain‐like protein (MLKL), an indispensable event for execution of necroptosis, is associated with the progression of DCM. Methods and results Patients with DCM (n = 56, 56 ± 15 years of age; 68% male) were enrolled for immunohistochemical analyses of biopsies. Adverse events were defined as a composite of death or admission for heart failure or ventricular arrhythmia. Compared with the normal myocardium, increased signals of MLKL phosphorylation were detected in the nuclei, cytoplasm, and intercalated discs of cardiomyocytes in biopsy samples from DCM patients. The phosphorylated MLKL (p‐MLKL) signal was increased in enlarged nuclei or nuclei with bizarre shapes in hypertrophied cardiomyocytes. Nuclear p‐MLKL level was correlated negatively with septal peak myocardial velocity during early diastole (r = −0.327, P = 0.019) and was correlated positively with tricuspid regurgitation pressure gradient (r = 0.339, P = 0.023), while p‐MLKL level in intercalated discs was negatively correlated with mean left ventricular wall thickness (r = −0.360, P = 0.014). During a median follow‐up period of 3.5 years, 10 patients (18%) had adverse events. To examine the difference in event rates according to p‐MLKL expression levels, patients were divided into two groups by using the median value of nuclear p‐MLKL or intercalated disc p‐MLKL. A group with high nuclear p‐MLKL level (H‐nucMLKL group) had a higher adverse event rate than did a group with low nuclear p‐MLKL level (L‐nucMLKL group) (32% vs. 4%, P = 0.012), and Kaplan–Meier survival curves showed that the adverse event‐free survival rate was lower in the H‐nucMLKL group than in the L‐nucMLKL group (P = 0.019 by the log‐rank test). Such differences were not detected between groups divided by a median value of intercalated disc p‐MLKL. In δ‐sarcoglycan‐deficient (Sgcd−/−) mice, a model of DCM, total p‐MLKL and nuclear p‐MLKL levels were higher than in wild‐type mice. Conclusion The results suggest that increased localization of nuclear p‐MLKL in cardiomyocytes is associated with left ventricular diastolic dysfunction and future adverse events in DCM.

A year in heart failure: updates of clinical and preclinical findings

“…tested whether phosphorylation of mixed lineage kinase domain‐like protein (MLKL) is associated with the progression of DCM. The results suggest that increased localization of nuclear phosphorylated MLKL in cardiomyocytes is associated with left ventricular diastolic dysfunction and future adverse events in DCM 62 …”

“…The results suggest that increased localization of nuclear phosphorylated MLKL in cardiomyocytes is associated with left ventricular diastolic dysfunction and future adverse events in DCM. 62 Although the nitric oxide (NO) signalling pathway has been implicated in HFpEF, the involvement of this pathway in the pathophysiology of HFpEF is not entirely clear. Piatek et al conducted a clinical study on 73 prospectively enrolled patients.…”

Luteolin-7-O-β-d-glucuronide Ameliorates Cerebral Ischemic Injury: Involvement of RIP3/MLKL Signaling Pathway

“…Then, the activated MLKL is multimerized within the cytoplasm, giving rise to the formation of a necrosome [21]. A crucial role of the nuclear-cytoplasmic shuttling of MLKL in pro-necroptotic signaling has been unveiled recently in animal models and patients [35,36]. The association of MLKL with the cell membrane in necroptotic death is preceded by the translocation of phosphorylated MLKL to the nucleus [37].…”