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SKI activates the Hippo pathway via LIMD1 to inhibit cardiac fibroblast activation
- Source :
- Basic Research in Cardiology
- Publication Year :
- 2021
- Publisher :
- Springer Science and Business Media LLC, 2021.
-
Abstract
- We have previously shown that overexpression of SKI, an endogenous TGF-β1 repressor, deactivates the pro-fibrotic myofibroblast phenotype in the heart. We now show that SKI also functions independently of SMAD/TGF-β signaling, by activating the Hippo tumor-suppressor pathway and inhibiting the Transcriptional co-Activator with PDZ-binding motif (TAZ or WWTR1). The mechanism(s) by which SKI targets TAZ to inhibit cardiac fibroblast activation and fibrogenesis remain undefined. A rat model of post-myocardial infarction was used to examine the expression of TAZ during acute fibrogenesis and chronic heart failure. Results were then corroborated with primary rat cardiac fibroblast cell culture performed both on plastic and on inert elastic substrates, along with the use of siRNA and adenoviral expression vectors for active forms of SKI, YAP, and TAZ. Gene expression was examined by qPCR and luciferase assays, while protein expression was examined by immunoblotting and fluorescence microscopy. Cell phenotype was further assessed by functional assays. Finally, to elucidate SKI’s effects on Hippo signaling, the SKI and TAZ interactomes were captured in human cardiac fibroblasts using BioID2 and mass spectrometry. Potential interactors were investigated in vitro to reveal novel mechanisms of action for SKI. In vitro assays on elastic substrates revealed the ability of TAZ to overcome environmental stimuli and induce the activation of hypersynthetic cardiac myofibroblasts. Further cell-based assays demonstrated that SKI causes specific proteasomal degradation of TAZ, but not YAP, and shifts actin cytoskeleton dynamics to inhibit myofibroblast activation. These findings were supported by identifying the bi-phasic expression of TAZ in vivo during post-MI remodeling and fibrosis. BioID2-based interactomics in human cardiac fibroblasts suggest that SKI interacts with actin-modifying proteins and with LIM Domain-containing protein 1 (LIMD1), a negative regulator of Hippo signaling. Furthermore, we found that LATS2 interacts with TAZ, whereas LATS1 does not, and that LATS2 knockdown prevented TAZ downregulation with SKI overexpression. Our findings indicate that SKI’s capacity to regulate cardiac fibroblast activation is mediated, in part, by Hippo signaling. We postulate that the interaction between SKI and TAZ in cardiac fibroblasts is arbitrated by LIMD1, an important intermediary in focal adhesion-associated signaling pathways. This study contributes to the understanding of the unique physiology of cardiac fibroblasts, and of the relationship between SKI expression and cell phenotype. Supplementary Information The online version contains supplementary material available at 10.1007/s00395-021-00865-9.
- Subjects :
- Male
TAZ
0301 basic medicine
animal structures
Physiology
Cardiac fibrosis
Myocardial Infarction
WWTR1
SMAD
Rats, Sprague-Dawley
03 medical and health sciences
0302 clinical medicine
Proto-Oncogene Proteins
Physiology (medical)
medicine
Animals
Hippo Signaling Pathway
Myofibroblasts
Cells, Cultured
Heart Failure
Hippo signaling pathway
Ventricular Remodeling
Chemistry
Myocardium
Hippo signaling
Intracellular Signaling Peptides and Proteins
Original Contribution
Extracellular matrix
Fibroblasts
LIM Domain Proteins
SKI
medicine.disease
Actin cytoskeleton
Fibrosis
Rats
Cell biology
Disease Models, Animal
Phenotype
030104 developmental biology
Transcriptional Coactivator with PDZ-Binding Motif Proteins
Fibroblast
Signal transduction
Cardiology and Cardiovascular Medicine
human activities
Myofibroblast
030217 neurology & neurosurgery
Subjects
Details
- ISSN :
- 14351803 and 03008428
- Volume :
- 116
- Database :
- OpenAIRE
- Journal :
- Basic Research in Cardiology
- Accession number :
- edsair.doi.dedup.....8056941623b3cd6db791b339e12f41a2