YAP plays a crucial role in the development of cardiomyopathy in lysosomal storage diseases
Shohei Ikeda, Jihoon Nah, Akihiro Shirakabe, Peiyong Zhai, Shin-ichi Oka, Sebastiano Sciarretta, Kun-Liang Guan, Hiroaki Shimokawa, Junichi Sadoshima
Shohei Ikeda, Jihoon Nah, Akihiro Shirakabe, Peiyong Zhai, Shin-ichi Oka, Sebastiano Sciarretta, Kun-Liang Guan, Hiroaki Shimokawa, Junichi Sadoshima
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Research Article Cardiology

YAP plays a crucial role in the development of cardiomyopathy in lysosomal storage diseases

Abstract

Lysosomal dysfunction caused by mutations in lysosomal genes results in lysosomal storage disorder (LSD), characterized by accumulation of damaged proteins and organelles in cells and functional abnormalities in major organs, including the heart, skeletal muscle, and liver. In LSD, autophagy is inhibited at the lysosomal degradation step and accumulation of autophagosomes is observed. Enlargement of the left ventricle (LV) and contractile dysfunction were observed in RagA/B cardiac-specific KO (cKO) mice, a mouse model of LSD in which lysosomal acidification is impaired irreversibly. YAP, a downstream effector of the Hippo pathway, was accumulated in RagA/B cKO mouse hearts. Inhibition of YAP ameliorated cardiac hypertrophy and contractile dysfunction and attenuated accumulation of autophagosomes without affecting lysosomal function, suggesting that YAP plays an important role in mediating cardiomyopathy in RagA/B cKO mice. Cardiomyopathy was also alleviated by downregulation of Atg7, an intervention to inhibit autophagy, whereas it was exacerbated by stimulation of autophagy. YAP physically interacted with transcription factor EB (TFEB), a master transcription factor that controls autophagic and lysosomal gene expression, thereby facilitating accumulation of autophagosomes without degradation. These results indicate that accumulation of YAP in the presence of LSD promotes cardiomyopathy by stimulating accumulation of autophagosomes through activation of TFEB.

Authors

Shohei Ikeda, Jihoon Nah, Akihiro Shirakabe, Peiyong Zhai, Shin-ichi Oka, Sebastiano Sciarretta, Kun-Liang Guan, Hiroaki Shimokawa, Junichi Sadoshima

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Figure 5

Suppression of autophagy alleviates cardiac dysfunction in RagA/B cKO mice.

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Suppression of autophagy alleviates cardiac dysfunction in RagA/B cKO mi...
(A and B) CMs were transduced with Ad-lacZ, Ad-sh-RagA+Ad-sh-RagB, or Ad-sh-RagA+Ad-sh-RagB+Ad-sh-Atg7. (A) Cell viability quantified by CellTiter-Blue assay. n = 4. Values were measured from more than 8 different wells per experiment. (B) CMs were transduced with Ad-tandem fluorescent LC3, and accumulation of autophagosomes (yellow puncta) and autolysosomes (red puncta) was evaluated. n = 3. Values were measured for more than 50 cells per experiment. Scale bar: 20 μm. (C) Percentage of cells with PNS. n = 4–7. In each mouse, cells with PNS were counted from more than 100 CMs. (D) Cells were treated with DMOS, zVAD, or Nec1 with siRagA/B or siCont. Cell viability quantified by CellTiter-Blue assay. n = 4. In each experiment, cell viability was evaluated from more than 8 different wells. (E) HW/TL in WT, Atg7 hcKO, RagA/B cKO, and RagA/B cKO+Atg7 hcKO mice at 2.5 months old. n = 4–11. (F) Percentage of FS in WT, Atg7 hcKO, RagA/B cKO, and RagA/B cKO+Atg7 hcKO mice at 2.5 months old. n = 4–14. (G) WT and RagA/B cKO mice were injected with TAT-scrambled (TS) or TAT–beclin 1 (TB) for 1 to 2 weeks. Quantitative analyses of echocardiographically evaluated percentage of FS are shown. n = 4–12. (H) Neonatal CMs were treated with 5 μM TAT–beclin 1, 20 nM bafilomycin A1 or TAT–beclin 1+Bafilomycin A1 for 24 hours. Cells were stained with cardiac troponin T, and cell size was quantified. n = 6. In each experiment, cell size was measured from more than 50 cells. Results are expressed as mean ± SD. *P < 0.05; **P < 0.01, ANOVA.