Related Experiment Video

Updated: Sep 10, 2025

Analysis of Somatic Hypermutation in the JH4 intron of Germinal Center B cells from Mouse Peyer's Patches
09:35

Analysis of Somatic Hypermutation in the JH4 intron of Germinal Center B cells from Mouse Peyer's Patches

Published on: April 20, 2021

6.8K

MKLN1-dependent GID4/CTLH E3 ubiquitin ligase complex assemblies are required to support B-cell antibody

Philip Barbulescu1, Matthew K Wong1, Leon Baronian1

  • 1Department of Immunology, University of Toronto, Toronto, ON, Canada.

Journal of Immunology (Baltimore, Md. : 1950)
|August 21, 2025
PubMed

C-terminal to LisH (CTLH) E3 ubiquitin ligase complexes regulate a broad range of biological processes and forms separate supramolecular CTLH-MKLN1 and CTLH-WDR26 assemblies possessing distinct substrate specificities. Our previous work revealed that the CTLH complex utilizes the FAM72A substrate adaptor to ubiquitinate and degrade the uracil-DNA glycosylase 2 (UNG2) base excision repair factor. This outcome in B cells permits deoxyuridine mutations catalyzed by activation-induced cytidine deaminase (AID) to persist toward mutational outcomes and drive antibody diversification events. Here, we report that Mkln1-/- mice specifically lacking assembly of CTLH-MKLN1 complexes display reduced somatic hypermutation and class switch recombination frequencies due to increased UNG2, similar to Fam72a-/- mice. Strikingly, Mkln1-/- mice showed increased germinal center B cells and defects during B-cell development, a phenotype not observed in Fam72a-/- mice, suggesting that MKLN1 regulates proteins that are independent of FAM72A. Together, this work identifies that CTLH-MKLN1 ubiquitin E3 ligase complexes are critical in generating effective humoral immune responses and reveals distinctions between FAM72A-dependent and -independent CTLH complex modalities.

Keywords:
B cellsC-terminal to LisHUNG2class switch recombinationsomatic hypermutation

More Related Videos

Combined Immunofluorescence and DNA FISH on 3D-preserved Interphase Nuclei to Study Changes in 3D Nuclear Organization13:55

Combined Immunofluorescence and DNA FISH on 3D-preserved Interphase Nuclei to Study Changes in 3D Nuclear Organization

Published on: February 3, 2013

18.6K
Myeloid Innate Signaling Pathway Regulation by MALT1 Paracaspase Activity07:09

Myeloid Innate Signaling Pathway Regulation by MALT1 Paracaspase Activity

Published on: January 7, 2019

7.6K

Related Concept Videos

B Cell Activation and Differentiation01:24

B Cell Activation and Differentiation

The adaptive immune response, a sophisticated defense mechanism, relies on the activation and differentiation of B lymphocytes, or B cells. These processes enable our bodies to mount a tailored response against specific pathogens such as bacteria, free virus particles, toxins, and parasites.
When naive B cells encounter a specific antigen that can bind to the B cell receptor (BCR) on their surface, they undergo sensitization to respond to the antigen's presence. Sensitization begins with...
5.6K
Protein Complexes with Interchangeable Parts01:57

Protein Complexes with Interchangeable Parts

Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order...
2.6K
Diversity of Antigen Receptors01:28

Diversity of Antigen Receptors

Antigen receptors are essential components of the immune system crucial in defending the body against foreign invaders. These receptors are present on the surface of B and T cells, enabling them to recognize antigens and mount an appropriate immune response.
Before encountering any antigen, lymphocytes express these receptors. On B cells, the antigen receptor is a membrane-bound antibody molecule called BCR; on T cells, it is a T cell receptor or TCR. B and T cell receptors are composed of two...
797
T Cell Activation and Clonal Selection01:22

T Cell Activation and Clonal Selection

T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...
4.5K