BAtCHing stem-like T cells during exhaustion

BTB domain and CNC homolog 2: A master regulator that controls immune response and cancer progression

BTB domain and CNC homolog 2 (BACH2) is a transcription repressor from the basic region leucine zipper (bZIP) family. Although BACH2 is predominantly expressed in lymphoid cells, it plays pivotal roles throughout hematological development and differentiation, ranging from the regulation of hematopoietic stem and progenitor cell (HSPC) lineage commitment to the development of both innate and adaptive immune cells. Given its extensive regulation of immunity, it is not surprising that BACH2 has been implicated in cancer, particularly in hematological malignancies. While multiple findings indicate that BACH2 acts primarily as a tumor suppressor, other findings suggest that BACH2, whether within tumor cells or their surrounding microenvironment, may contribute to tumorigenesis and progression, highlighting the complexity of its roles and the diverse networks involved in different contexts. In this review, we provide a comprehensive overview of the evolving roles of BACH2 across various stages of hematopoiesis, with a particular focus on its associations with cancer and its therapeutic potential in a wide range of cancer types.

Intergenic risk variant rs56258221 skews the fate of naive CD4+ T cells via miR4464-BACH2 interplay in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is an immune-mediated liver disease of unknown pathogenesis, with a high risk to develop cirrhosis and malignancies. Functional dysregulation of T cells and association with genetic polymorphisms in T cell-related genes were previously reported for PSC. Here, we genotyped a representative PSC cohort for several disease-associated risk loci and identified rs56258221 (BACH2/MIR4464) to correlate with not only the peripheral blood T cell immunophenotype but also the functional capacities of naive CD4+ T (CD4+ TN) cells in people with PSC. Mechanistically, rs56258221 leads to an increased expression of miR4464, in turn causing attenuated translation of BACH2, a major gatekeeper of T cell quiescence. Thereby, the fate of CD4+ TN is skewed toward polarization into pro-inflammatory subsets. Clinically, people with PSC carrying rs56258221 show signs of accelerated disease progression. The data presented here highlight the importance of assigning functional outcomes to disease-associated genetic polymorphisms as potential drivers of diseases.

The role of Bach2 in regulating CD8 + T cell development and function

Bach2 was initially discovered in B cells, where it was revealed to control the transcription involved in cell differentiation. Bach2 is intimately connected to CD8 + T lymphocytes in various differentiation states and subsets according to recent findings. Bach2 can regulate primitive T cells, stimulate the development and differentiation of memory CD8 + T cells, inhibit the differentiation of effector CD8 + T cells, and play a significant role in the exhaustion of CD8 + T cells. The appearance and development of diseases are tightly linked to irregular CD8 + T cell differentiation and function. Accordingly, Bach2 offers novel approaches and possible targets for the clinical treatment of associated disorders based on research on these pathways. Here, we summarize the role of Bach2 in the function and differentiation of CD8 + T cells and its potential clinical applications.