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USP36 SUMOylates Las1L and Promotes Its Function in Pre-Ribosomal RNA ITS2 Processing
Yanping Li1, Yunhan Yang1, Rosalie C Sears1
1Department of Molecular and Medical Genetics, School of Medicine, and the OHSU Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon.
Cancer Research Communications
|October 2, 2024
Summary
The ubiquitin-specific protease USP36 regulates ribosome biogenesis by controlling the Las1L-Nol9 complex. USP36
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Ribosome biogenesis is crucial for cell function and its dysregulation is linked to diseases like cancer.
- The Las1L-Nol9 complex is essential for 60S ribosome maturation, specifically for processing the internal transcribed spacer 2 (ITS2) of rRNA.
- The precise regulatory mechanisms governing the Las1L-Nol9 complex activity within the cell remain largely unknown.
Purpose of the Study:
- To identify novel regulators of the Las1L-Nol9 complex and elucidate their role in ribosome biogenesis.
- To investigate the function of USP36 in the context of the Las1L-Nol9 complex and rRNA processing.
- To determine the specific molecular mechanisms by which USP36 influences Las1L-Nol9 activity and ribosome production.
Main Methods:
- Co-immunoprecipitation assays to confirm interactions between USP36, Las1L, and Nol9.
- Western blotting to assess the stability and modification states (ubiquitination, SUMOylation) of Las1L.
- Site-directed mutagenesis (K565R) of Las1L to investigate the functional significance of SUMOylation.
- Functional rescue experiments following knockdown of endogenous Las1L to assess the role of USP36 and Las1L mutants in ITS2 processing.
Main Results:
- USP36 directly interacts with both Las1L and Nol9, regulating their stability through deubiquitination.
- USP36 mediates the SUMOylation of Las1L, primarily at lysine 565 (K565).
- Mutation of K565 to arginine (K565R) abrogates the function of Las1L in ITS2 processing, despite maintaining complex formation and protein levels.
- USP36-mediated Las1L SUMOylation at K565 is critical for efficient ITS2 processing and subsequent ribosome biogenesis.
Conclusions:
- USP36 acts as a novel dual-function regulator, deubiquitinating and SUMOylating Las1L.
- USP36-mediated SUMOylation of Las1L at K565 is essential for pre-rRNA ITS2 processing.
- This study reveals a new regulatory pathway for ribosome biogenesis involving USP36 and the Las1L-Nol9 complex.
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