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Generation of the short TRIM32 isoform is regulated by Lys 247 acetylation and a PEST sequence
Juncal Garcia-Garcia1, Katrine Stange Overå1, Waqas Khan1
1Department of Medical Biology, Autophagy Research Group, University of Tromsø-The Arctic University of Norway, Tromsø, Norway.
Abstract:
TRIM32 is an E3 ligase implicated in diverse biological pathways and pathologies such as muscular dystrophy and cancer. TRIM32 are expressed both as full-length proteins, and as a truncated protein. The mechanisms for regulating these isoforms are poorly understood. Here we identify a PEST sequence in TRIM32 located in the unstructured region between the RING-BBox-CoiledCoil domains and the NHL repeats. The PEST sequence directs cleavage of TRIM32, generating a truncated protein similarly to the short isoform. We map three lysine residues that regulate PEST mediated cleavage and auto-ubiquitylation activity of TRIM32. Mimicking acetylation of lysine K247 completely inhibits TRIM32 cleavage, while the lysines K50 and K401 are implicated in auto-ubiquitylation activity. We show that the short isoform of TRIM32 is catalytic inactive, suggesting a dominant negative role. These findings uncover that TRIM32 is regulated by post-translational modifications of three lysine residues, and a conserved PEST sequence.
Insights
Tripartite motif 32 (TRIM32) protein regulation involves a PEST sequence and three lysine residues. These modifications control TRIM32 cleavage into isoforms and its auto-ubiquitylation, impacting muscular dystrophy and cancer pathways.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Tripartite motif 32 (TRIM32) is an E3 ligase involved in various biological processes and diseases, including muscular dystrophy and cancer.
- TRIM32 exists as both full-length and truncated isoforms, but the regulatory mechanisms controlling these forms are not well understood.
Purpose of the Study:
- To investigate the mechanisms regulating TRIM32 isoforms.
- To identify regulatory elements and post-translational modifications controlling TRIM32 cleavage and activity.
Main Methods:
- Identification and characterization of a PEST sequence in TRIM32.
- Mapping of lysine residues involved in PEST-mediated cleavage and auto-ubiquitylation.
- Analysis of TRIM32 isoform catalytic activity and functional roles.
Main Results:
- A conserved PEST sequence in TRIM32 mediates its cleavage, generating a truncated isoform.
- Three specific lysine residues (K247, K50, K401) regulate PEST-mediated cleavage and auto-ubiquitylation.
- Acetylation of K247 inhibits TRIM32 cleavage, while K50 and K401 are crucial for auto-ubiquitylation.
- The short TRIM32 isoform is catalytically inactive, suggesting a dominant-negative function.
Conclusions:
- TRIM32 activity and isoform generation are regulated by post-translational modifications at specific lysine residues.
- A conserved PEST sequence plays a critical role in TRIM32 cleavage and isoform regulation.
- Understanding TRIM32 regulation provides insights into its role in muscular dystrophy and cancer.
