MicroRNA-155 controls affinity-based selection by protecting c-MYC+ B cells from apoptosis
Rinako Nakagawa, … , Robert Brink, Elena Vigorito
Rinako Nakagawa, … , Robert Brink, Elena Vigorito
Published December 14, 2015
Citation Information: J Clin Invest. 2016;126(1):377-388. https://doi.org/10.1172/JCI82914.
View: Text | PDF
Research Article Immunology

MicroRNA-155 controls affinity-based selection by protecting c-MYC+ B cells from apoptosis

Abstract

The production of high-affinity antibodies by B cells is essential for pathogen clearance. Antibody affinity for antigen is increased through the affinity maturation in germinal centers (GCs). This is an iterative process in which B cells cycle between proliferation coupled with the acquisition of mutations and antigen-based positive selection, resulting in retention of the highest-affinity B cell clones. The posttranscriptional regulator microRNA-155 (miR-155) is critical for efficient affinity maturation and the maintenance of the GCs; however, the cellular and molecular mechanism by which miR-155 regulates GC responses is not well understood. Here, we utilized a miR-155 reporter mouse strain and showed that miR-155 is coexpressed with the proto-oncogene encoding c-MYC in positively selected B cells. Functionally, miR-155 protected positively selected c-MYC+ B cells from apoptosis, allowing clonal expansion of this population, providing an explanation as to why Mir155 deletion impairs affinity maturation and promotes the premature collapse of GCs. We determined that miR-155 directly inhibits the Jumonji family member JARID2, which enhances B cell apoptosis when overexpressed, and thereby promotes GC B cell survival. Our findings also suggest that there is cooperation between c-MYC and miR-155 during the normal GC response, a cooperation that may explain how c-MYC and miR-155 can collaboratively function as oncogenes.

Authors

Rinako Nakagawa, Rebecca Leyland, Michael Meyer-Hermann, Dong Lu, Martin Turner, Giuseppina Arbore, Tri Giang Phan, Robert Brink, Elena Vigorito

×

Figure 7

The miR-155 target gene Jarid2 regulates the apoptosis of GC B cells.

Options: View larger image (or click on image) Download as PowerPoint
The miR-155 target gene Jarid2 regulates the apoptosis of GC B cells. (A...
(A) SWHEL Mir155LacZ/+ or SWHEL Mir155LacZ/– B cells were adoptively transferred into CD45.1+ congenic recipients that were injected with HEL3X-SRBC. After 5 days, donor cells were sorted as described in Figure 2A. Jarid2 transcripts were measured by qPCR using Hprt for normalization. The mean ± SEM is presented from a representative data of 2 independent experiments (n = 6). *P < 0.05, ***P < 0.001 using 1-way ANOVA followed by a Tukey’s multiple comparisons post-test. (B) SWHEL Mir155+/+ activated B cells were transduced with JARID2/IRES-GFP virus or IRES-GFP control (empty vector). The GFP+ cells were sorted, and gene overexpression efficiency was evaluated by qPCR. The mean ± SEM of experiments is shown (n = 4) (left). Retrovirally transduced SWHEL B cells were adoptively transferred into HEL-SRBC–injected CD45.1+ congenic mice (Supplemental Figure 5). Four days later, apoptosis was measured using AnnexinV and 7-AAD in GC HEL-binders split on the bases of GFP expression and DZ/LZ status as described in Supplemental Figure 6. The ratio of apoptosis was calculated as the relative values of the GFP+ to the GFP– counterparts to correct for potential biases across cultures. Data are pooled from 2 independent experiments and presented as the mean ± SEM. Each symbol represents a mouse. (C) The same method as B was used, except that activated SWHEL Mir155–/– B cells were retrovirally transduced with RNAi-JARID2/IRES-GFP or control vector, and Jarid2 silencing efficiency was evaluated by qPCR. Data are pooled from 2 independent experiments and presented as mean ± SEM. Each symbol represents a mouse. *P < 0.05, **P < 0.005 using two-tailed unpaired t test (B and C).