B-cells are antibody-producing cells of the adaptive immune system. Approximately 75% of all newly generated B-cells in the bone marrow are autoreactive and express potentially harmful autoantibodies. To prevent autoimmune disease, the immune system has evolved a powerful mechanism to eliminate autoreactive B-cells, termed negative B-cell selection. While designed to remove autoreactive clones during early B-cell development, our laboratory recently discovered that transformed B-cells in leukemia and lymphoma are also subject to negative selection. Indeed, besides the risk of developing autoimmune disease, B-cells are inherently prone to malignant transformation: to produce high-affinity antibodies, B-cells undergo multiple rounds of somatic immunoglobulin gene recombination and hypermutation. Reflecting high frequencies of DNA-breaks, adaptive immune protection by B-cells comes with a dramatically increased risk of development of leukemia and lymphoma. Of note, B-cells exist under conditions of chronic restriction of energy metabolism. Here we discuss how these metabolic gatekeeper functions during B-cell development provide a common mechanism for the removal of autoreactive and premalignant B-cells to safeguard against both autoimmune diseases and B-cell malignancies.
Depicted as playing cards belonging to the same suit, the paralogous MLL3 and MLL4 lysine methyltransferase (KMT) complexes share a common set of core and auxiliary subunits as well as similar histone methylase functions. On each card, largely divergent processes are described on opposing sides – highlighting the potential capacity of these KMT complexes to participate in both tumor-supportive and tumor-suppressive mechanisms. To understand how MLL3 and MLL4 can regulate such diverse and sometimes contrasting processes, read more in this review article by Wang and colleagues (pp. 1041–1054). Cover artwork created by Marvin Aberin with Biorender.com.
Metabolic determinants of B-cell selection
Lai N. Chan, Eamon Aghania, Etienne Leveille, Markus Müschen; Metabolic determinants of B-cell selection. Biochem Soc Trans 30 June 2021; 49 (3): 1467–1478. doi: https://doi.org/10.1042/BST20201316
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