Deubiquitinase OTUD5 is a positive regulator of mTORC1 and mTORC2 signaling pathways
Jin Hwa Cho1, Kidae Kim1,2, Sung Ah Kim1,3
1Disease Target Structure Research Center, KRIBB, Daejeon, 34141, Republic of Korea.
Abstract:
The mammalian Target of Rapamycin (mTOR) pathway regulates a variety of physiological processes, including cell growth and cancer progression. The regulatory mechanisms of these signals are extremely complex and comprise many feedback loops. Here, we identified the deubiquitinating enzyme ovarian tumor domain-containing protein 5 (OTUD5) as a novel positive regulator of the mTOR complex (mTORC) 1 and 2 signaling pathways. We demonstrated that OTUD5 stabilized β-transducin repeat-containing protein 1 (βTrCP1) proteins via its deubiquitinase (DUB) activity, leading to the degradation of Disheveled, Egl-10, and pleckstrin domain-containing mTOR-interacting protein (DEPTOR), which is an inhibitory protein of mTORC1 and 2. We also showed that mTOR directly phosphorylated OTUD5 and activated its DUB activity. RNA sequencing analysis revealed that OTUD5 regulates the downstream gene expression of mTOR. Additionally, OTUD5 depletion elicited several mTOR-related phenotypes such as decreased cell size and increased autophagy in mammalian cells as well as the suppression of a dRheb-induced curled wing phenotype by RNA interference of Duba, a fly ortholog of OTUD5, in Drosophila melanogaster. Furthermore, OTUD5 knockdown inhibited the proliferation of the cancer cell lines with mutations activating mTOR pathway. Our results suggested a positive feedback loop between OTUD5 and mTOR signaling pathway.
Insights
Ovarian tumor domain-containing protein 5 (OTUD5) acts as a novel positive regulator of the mTOR pathway. It stabilizes proteins, leading to mTOR activation and influencing cell growth and cancer progression.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The mammalian Target of Rapamycin (mTOR) pathway is crucial for regulating cell growth, metabolism, and cancer progression.
- Complex feedback loops govern mTOR signaling, and novel regulatory mechanisms are actively being investigated.
Purpose of the Study:
- To identify novel regulators of the mTOR complex (mTORC) 1 and 2 signaling pathways.
- To elucidate the role of ovarian tumor domain-containing protein 5 (OTUD5) in mTOR signaling.
Main Methods:
- Deubiquitinase (DUB) activity assays to assess OTUD5 function.
- Western blotting to detect protein stabilization and degradation.
- RNA sequencing to analyze downstream gene expression.
- Cell-based assays and Drosophila melanogaster models to evaluate mTOR-related phenotypes.
Main Results:
- OTUD5 was identified as a positive regulator of mTORC1 and mTORC2 signaling.
- OTUD5 stabilizes β-transducin repeat-containing protein 1 (βTrCP1), promoting the degradation of the mTOR inhibitor DEPTOR.
- mTOR directly phosphorylates and activates OTUD5, forming a positive feedback loop.
- OTUD5 depletion caused decreased cell size, increased autophagy, and suppressed cancer cell proliferation.
Conclusions:
- OTUD5 is a novel positive regulator of mTOR signaling through a feedback loop involving mTOR-mediated phosphorylation and DEPTOR degradation.
- OTUD5 plays a significant role in cell growth, autophagy, and cancer progression, making it a potential therapeutic target.
Related Concept Videos
03:03mTOR Signaling and Cancer Progression
The mTOR pathway or the...
01:22PI3K/mTOR/AKT Signaling Pathway
02:58Regulated Protein Degradation
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
02:58Regulated Protein Degradation
02:04Covalently Linked Protein Regulators
These groups modify specific amino acids in a protein....
02:04Covalently Linked Protein Regulators