Limits...
V(D)J recombination process and the Pre-B to immature B-cells transition are altered in Fanca − / − mice

View Article: PubMed Central - PubMed

ABSTRACT

B-lymphocytes in the bone marrow (BM) must generate a functional B-cell receptor and overcome the negative selection induced by reactivity with autoantigens. Two rounds of DNA recombination are required for the production of functional immunoglobulin heavy (Ig-HCs) and light (LCs) chains necessary for the continuation of B-lymphocyte development in the BM. Both rounds depend on the joint action of recombination activating gene-1 (RAG-1) and RAG-2 endonucleases with the DNA non-homologous end-joining pathway. Loss of the FANC gene leads to the chromosome breakage and cancer predisposition syndrome Fanconi anemia. Because the FANC proteins are involved in certain aspects of the recombination process, we sought to determine the impact of the FANC pathway on the Ig diversification process using Fanca−/− mice. In this work we demonstrated that Fanca−/− animals have a mild B-cell differentiation defect characterized by a specific alteration of the IgM− to IgM+ transition of the B220low B-cell population. Pre-B cells from Fanca−/− mice show evidence of impaired kLC rearrangement at the level of the Vk-Jk junction. Furthermore, Fanca−/− mice showed a skewed Vκ gene usage during formation of the LCs Vk-Jk junctions. Therefore, the Fanca protein appears as a yet unidentified factor involved in the primary diversification of Ig.

No MeSH data available.


Related in: MedlinePlus

Fanca−/− mice show moderate impairment of the IgM− to IgM+ transition in the BM.(A) A representative flow cytometry plot used to identify and estimate the frequency of B220+ (total B), B220+ IgM− CD43low (pre B) and B220+ IgM− CD43high (pro B) cells isolated from WT and Fanca−/− mouse BM. (B) Quantification of the data in A (mean ± SEM; n = 5 par genotype). (C) A representative flow cytometry plot used to identify and estimate the frequency of IgM− B220low and IgM+ B220low populations of BM cells from WT and Fanca−/− mice. (D) The ratio of IgM− B220low cells and IgM+ B220low immature B cells identified as shown in C. (n = 8 for Fanca−/− mice; n = 7 for WT mice *p < 0.05). (E) Flow cytometry representation of B220+ IgM+ cells derived from WT and Fanca−/− mouse spleen. (F) Average percentage of B cells (B220+ IgM−) in the spleen of WT and Fanca−/− mice (mean ± SEM).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5121645&req=5

f1: Fanca−/− mice show moderate impairment of the IgM− to IgM+ transition in the BM.(A) A representative flow cytometry plot used to identify and estimate the frequency of B220+ (total B), B220+ IgM− CD43low (pre B) and B220+ IgM− CD43high (pro B) cells isolated from WT and Fanca−/− mouse BM. (B) Quantification of the data in A (mean ± SEM; n = 5 par genotype). (C) A representative flow cytometry plot used to identify and estimate the frequency of IgM− B220low and IgM+ B220low populations of BM cells from WT and Fanca−/− mice. (D) The ratio of IgM− B220low cells and IgM+ B220low immature B cells identified as shown in C. (n = 8 for Fanca−/− mice; n = 7 for WT mice *p < 0.05). (E) Flow cytometry representation of B220+ IgM+ cells derived from WT and Fanca−/− mouse spleen. (F) Average percentage of B cells (B220+ IgM−) in the spleen of WT and Fanca−/− mice (mean ± SEM).

Mentions: To determine whether Fanca is involved in the mechanism of V(D)J recombination in B cells, we first analysed lymphoid tissue development in the BM and spleen of 8-week old Fanca−/− and WT mice. Flow cytometry analysis of the BM showed no quantitative difference in the proportion of total B cells (B220+), pro-B cells (B220+ IgM− CD43high), and pre-B cells (B220+ IgM− CD43low) between Fanca−/− and WT mice (Fig. 1A,B).


V(D)J recombination process and the Pre-B to immature B-cells transition are altered in Fanca − / − mice
Fanca−/− mice show moderate impairment of the IgM− to IgM+ transition in the BM.(A) A representative flow cytometry plot used to identify and estimate the frequency of B220+ (total B), B220+ IgM− CD43low (pre B) and B220+ IgM− CD43high (pro B) cells isolated from WT and Fanca−/− mouse BM. (B) Quantification of the data in A (mean ± SEM; n = 5 par genotype). (C) A representative flow cytometry plot used to identify and estimate the frequency of IgM− B220low and IgM+ B220low populations of BM cells from WT and Fanca−/− mice. (D) The ratio of IgM− B220low cells and IgM+ B220low immature B cells identified as shown in C. (n = 8 for Fanca−/− mice; n = 7 for WT mice *p < 0.05). (E) Flow cytometry representation of B220+ IgM+ cells derived from WT and Fanca−/− mouse spleen. (F) Average percentage of B cells (B220+ IgM−) in the spleen of WT and Fanca−/− mice (mean ± SEM).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121645&req=5

f1: Fanca−/− mice show moderate impairment of the IgM− to IgM+ transition in the BM.(A) A representative flow cytometry plot used to identify and estimate the frequency of B220+ (total B), B220+ IgM− CD43low (pre B) and B220+ IgM− CD43high (pro B) cells isolated from WT and Fanca−/− mouse BM. (B) Quantification of the data in A (mean ± SEM; n = 5 par genotype). (C) A representative flow cytometry plot used to identify and estimate the frequency of IgM− B220low and IgM+ B220low populations of BM cells from WT and Fanca−/− mice. (D) The ratio of IgM− B220low cells and IgM+ B220low immature B cells identified as shown in C. (n = 8 for Fanca−/− mice; n = 7 for WT mice *p < 0.05). (E) Flow cytometry representation of B220+ IgM+ cells derived from WT and Fanca−/− mouse spleen. (F) Average percentage of B cells (B220+ IgM−) in the spleen of WT and Fanca−/− mice (mean ± SEM).
Mentions: To determine whether Fanca is involved in the mechanism of V(D)J recombination in B cells, we first analysed lymphoid tissue development in the BM and spleen of 8-week old Fanca−/− and WT mice. Flow cytometry analysis of the BM showed no quantitative difference in the proportion of total B cells (B220+), pro-B cells (B220+ IgM− CD43high), and pre-B cells (B220+ IgM− CD43low) between Fanca−/− and WT mice (Fig. 1A,B).

View Article: PubMed Central - PubMed

ABSTRACT

B-lymphocytes in the bone marrow (BM) must generate a functional B-cell receptor and overcome the negative selection induced by reactivity with autoantigens. Two rounds of DNA recombination are required for the production of functional immunoglobulin heavy (Ig-HCs) and light (LCs) chains necessary for the continuation of B-lymphocyte development in the BM. Both rounds depend on the joint action of recombination activating gene-1 (RAG-1) and RAG-2 endonucleases with the DNA non-homologous end-joining pathway. Loss of the FANC gene leads to the chromosome breakage and cancer predisposition syndrome Fanconi anemia. Because the FANC proteins are involved in certain aspects of the recombination process, we sought to determine the impact of the FANC pathway on the Ig diversification process using Fanca&minus;/&minus; mice. In this work we demonstrated that Fanca&minus;/&minus; animals have a mild B-cell differentiation defect characterized by a specific alteration of the IgM&minus; to IgM+ transition of the B220low B-cell population. Pre-B cells from Fanca&minus;/&minus; mice show evidence of impaired kLC rearrangement at the level of the Vk-Jk junction. Furthermore, Fanca&minus;/&minus; mice showed a skewed V&kappa; gene usage during formation of the LCs Vk-Jk junctions. Therefore, the Fanca protein appears as a yet unidentified factor involved in the primary diversification of Ig.

No MeSH data available.


Related in: MedlinePlus