TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagCS75Y Cardiomyopathy

Kim, M., Lu, L., Dvornikov, A.V., Ma, X., Ding, Y., Zhu, P., Olson, T.M., Lin, X., Xu, X.
International Journal of Molecular Sciences   22(11): (Journal)
Registered Authors
Ding, Yonghe, Lin, Xueying, Xu, Xiaolei, Zhu, Ping
RagCS75Y, Rags, TFEB, cardiomyopathy, mTOR
MeSH Terms
  • Active Transport, Cell Nucleus
  • Amino Acid Substitution
  • Animals
  • Autophagy
  • Base Sequence
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/biosynthesis
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/physiology*
  • Cardiomyopathy, Dilated/genetics*
  • Cardiomyopathy, Dilated/therapy
  • Cells, Cultured
  • Gain of Function Mutation*
  • Gene Knock-In Techniques
  • Gene Knockout Techniques
  • Heart Ventricles/cytology
  • Humans
  • Mice
  • Monomeric GTP-Binding Proteins/genetics*
  • Monomeric GTP-Binding Proteins/physiology
  • Mutation, Missense*
  • Myocytes, Cardiac/metabolism
  • Phenotype
  • Point Mutation*
  • Rats, Wistar
  • Recombinant Proteins/metabolism
  • Signal Transduction
  • TOR Serine-Threonine Kinases/antagonists & inhibitors*
  • Transcription Activator-Like Effector Nucleases
  • Zebrafish
  • Zebrafish Proteins/deficiency
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/physiology
34071043 Full text @ Int. J. Mol. Sci.
A de novo missense variant in Rag GTPase protein C (RagCS75Y) was recently identified in a syndromic dilated cardiomyopathy (DCM) patient. However, its pathogenicity and the related therapeutic strategy remain unclear. We generated a zebrafish RragcS56Y (corresponding to human RagCS75Y) knock-in (KI) line via TALEN technology. The KI fish manifested cardiomyopathy-like phenotypes and poor survival. Overexpression of RagCS75Y via adenovirus infection also led to increased cell size and fetal gene reprogramming in neonatal rat ventricle cardiomyocytes (NRVCMs), indicating a conserved mechanism. Further characterization identified aberrant mammalian target of rapamycin complex 1 (mTORC1) and transcription factor EB (TFEB) signaling, as well as metabolic abnormalities including dysregulated autophagy. However, mTOR inhibition failed to ameliorate cardiac phenotypes in the RagCS75Y cardiomyopathy models, concomitant with a failure to promote TFEB nuclear translocation. This observation was at least partially explained by increased and mTOR-independent physical interaction between RagCS75Y and TFEB in the cytosol. Importantly, TFEB overexpression resulted in more nuclear TFEB and rescued cardiomyopathy phenotypes. These findings suggest that S75Y is a pathogenic gain-of-function mutation in RagC that leads to cardiomyopathy. A primary pathological step of RagCS75Y cardiomyopathy is defective mTOR-TFEB signaling, which can be corrected by TFEB overexpression, but not mTOR inhibition.
Genes / Markers
Show all Figures
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes