Activation of Hippo signaling pathway mediates mitochondria dysfunction and dilated cardiomyopathy in mice

Abstract

Rationale: Mitochondrial dysfunction facilitates heart failure development forming a therapeutic target, but the mechanism involved remains unclear. We studied whether the Hippo signaling pathway mediates mitochondrial abnormalities that results in onset of dilated cardiomyopathy (DCM). Methods: Mice with DCM due to overexpression of Hippo pathway kinase Mst1 were studied. DCM phenotype was evident in adult animals but contractile dysfunction was identified as an early sign of DCM at 3 weeks postnatal. Electron microscopy, multi-omics and biochemical assays were employed. Results: In 3-week and adult DCM mouse hearts, cardiomyocyte mitochondria exhibited overt structural abnormalities, smaller size and greater number. RNA sequencing revealed comprehensive suppression of nuclear-DNA (nDNA) encoded gene-sets involved in mitochondria turnover and all aspects of metabolism. Changes in cardiotranscriptome were confirmed by lower protein levels of multiple mitochondrial proteins in DCM heart of both ages. Mitochondrial DNA-encoded genes were also downregulated; due apparently to repression of nDNA-encoded transcriptional factors. Lipidomics identified remodeling in cardiolipin acyl-chains, increased acylcarnitine content but lower coenzyme Q10 level. Mitochondrial dysfunction was featured by lower ATP content and elevated levels of lactate, branched-chain amino acids and reactive oxidative species. Mechanistically, inhibitory YAP-phosphorylation was enhanced, which was associated with attenuated binding of transcription factor TEAD1. Numerous suppressed mitochondrial genes were identified as YAP-targets. Conclusion: Hippo signaling activation mediates mitochondrial damage by repressing mitochondrial genes, which causally promotes the development of DCM. The Hippo pathway therefore represents a therapeutic target against mitochondrial dysfunction in cardiomyopathy.

Transcriptomic Analysis of Dysregulated Genes of the nDNA-mtDNA Axis in a Mouse Model of Dilated Cardiomyopathy

“…We previously performed RNA-sequencing of left ventricular tissues from transgenic strain of mice with cardiac overexpression of Mst1, an upper-stream kinase of Hippo pathway ( Yamamoto et al, 2003 ). The use of the α-myosin heavy chain promoter (α-MHC) allows for cardiomyocyte-restricted overexpression of Mst1 that drives the onset of DCM as thoroughly documented by our previous studies ( Nguyen et al, 2019 ; Wu et al, 2021 ). Male Mst1-TG (DCM) and non-TG littermate (nTG) mice were used.…”

“…Heart tissues from nTG and Mst1-TG mice were used for RNA-sequencing and immunoblotting. Animals were studied at a young (3 weeks) and adult (15 weeks) ages, representing early or severe stage of DCM, as being demonstrated previously ( Nguyen et al, 2019 ; Wu et al, 2021 ). Left ventricular tissues were homogenized in TRIzol and RNA isolation was done using RNA Miniprep Kit (Zymo Research), and transcriptome sequencing of extracted RNA was performed.…”

“…Left ventricular tissues were homogenized in TRIzol and RNA isolation was done using RNA Miniprep Kit (Zymo Research), and transcriptome sequencing of extracted RNA was performed. Details of transcriptome sequencing were provided in our previously published studies ( Nguyen et al, 2019 ; Wu et al, 2021 ).…”

“…Numerous studies have revealed mitochondrial dysfunction in the failing heart manifested as lower energy generation mismatching the demand, increased generation of reactive oxygen species, and cell death mediated by mitochondrial death signaling ( Murphy et al, 2016 ; Brown et al, 2017 ). Whereas the molecular mechanism responsible for mitochondrial dysfunction remains unclear, recent studies have demonstrated that activation of the Hippo signaling pathway is potent in mediating extensive suppression of mitochondrial genes together with significant mitochondrial dysfunction leading to DCM ( Liu et al, 2021 ; Wu et al, 2021 ).…”

“…Our recent study showed that cardiomyocyte-restricted overexpression of Mst1 (mammalian sterile 20-like kinase) leads to activation of the Hippo signaling pathway with extensive downregulation of multiple gene sets related to mitochondrial turnover and metabolism ( Wu et al, 2021 ). By employing transcriptome sequencing from Mst1-TG model, we conducted a detailed transcriptome analysis on changes not only in mtDNA-encoded genes, but also in several gene sets for proteins that form the nDNA-mtDNA axis participating in mtDNA transcription and translation.…”