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MARCH5-dependent NLRP3 ubiquitination is required for mitochondrial NLRP3-NEK7 complex formation and NLRP3

Yeon-Ji Park1,2, Niranjan Dodantenna3, Yonghyeon Kim1,2

  • 1Department of Biochemistry, Ajou University School of Medicine, Suwon, Korea.

The EMBO Journal
|August 14, 2023
PubMed

Insights

The E3 ligase MARCH5 regulates NLRP3 inflammasome activation by ubiquitination. This process is crucial for immune responses to pathogens and mitochondrial damage, impacting IL-1β and IL-18 secretion.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cellular Biology

Background:

  • The NLRP3 inflammasome is a critical immune sensor for pathogens and cellular damage.
  • Mitochondria play a significant role in NLRP3 inflammasome activation pathways.
  • NLRP3 inflammasome assembly and activation are tightly regulated processes.

Purpose of the Study:

  • To investigate the role of the E3 ligase MARCH5 in NLRP3 inflammasome activation.
  • To elucidate the mechanism by which MARCH5 regulates NLRP3 inflammasome assembly and function.
  • To determine the in vivo significance of MARCH5-mediated NLRP3 ubiquitination in immune responses.

Main Methods:

  • Utilized myeloid cell-specific March5 conditional knockout (cKO) mice.
  • Analyzed cytokine secretion (IL-1β, IL-18) in response to microbial challenges (LPS, Pseudomonas aeruginosa).
  • Investigated molecular interactions and ubiquitination sites (K324, K430) on NLRP3 using biochemical assays and mutant analysis.

Main Results:

  • March5 cKO mice showed impaired IL-1β and IL-18 secretion and reduced mortality upon infection.
  • MARCH5 directly interacts with NLRP3, promoting its K27-linked polyubiquitination at specific residues.
  • Ubiquitination-defective NLRP3 mutants failed to bind NEK7, oligomerize, or form ASC specks, diminishing IL-1β production.

Conclusions:

  • MARCH5 is a mitochondria-associated E3 ligase that ubiquitinates NLRP3.
  • MARCH5-dependent NLRP3 ubiquitination is essential for NEK7 binding, NLRP3 oligomerization, and inflammasome activation.
  • MARCH5 acts as a key regulator of NLRP3 inflammasome activation on mitochondria.
Keywords:
MARCH5NEK7NLRP3 inflammasomemitochondriaubiquitination

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