The H3K9me3-specific histone methyltransferase Setdb1 impacts on transcriptional regulation by repressing both developmental genes and retrotransposons. How impaired retrotransposon silencing may lead to developmental phenotypes is currently unclear. Here, we show that loss of Setdb1 in pro-B cells completely abrogates B cell development. In pro-B cells, Setdb1 is dispensable for silencing of lineage-inappropriate developmental genes. Instead, we detect strong derepression of endogenous murine leukemia virus (MLV) copies. This activation coincides with an unusual change in chromatin structure, with only partial loss of H3K9me3 and unchanged DNA methylation, but strongly increased H3K4me3. Production of MLV proteins leads to activation of the unfolded protein response pathway and apoptosis. Thus, our data demonstrate that B cell development depends on the proper repression of retrotransposon sequences through Setdb1.
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FEBS Lett
December 2024
Department of Medical Chemistry, Medical Research Laboratory, Institute of Integrated Research, Institute of Science Tokyo, Japan.
Phospholipids are asymmetrically distributed in the plasma membrane (PM), and scramblases disrupt this asymmetry by shuffling phospholipids. We recently identified mouse Tmem63b as a membrane structure-responsive scramblase. Tmem63b belongs to the TMEM63/OSCA family of ion channels; however, the conservation of the scramblase activity within this family remains unclear.
View Article and Find Full Text PDFHematology Am Soc Hematol Educ Program
December 2024
UT Southwestern Medical Center, BioCenter, Dallas, TX.
Classification of acute leukemia involves assigning lineage by resemblance of blasts to normal progenitor cells. This approach provides descriptive information that is useful for disease monitoring, provides clues to pathogenesis, and can help to select effective chemotherapeutic regimens. Acute leukemias of ambiguous lineage (ALAL) are those leukemias that either fail to show evidence of myeloid, B-lymphoid, or T-lymphoid lineage commitment or show evidence of commitment to more than 1 lineage, including mixed-phenotype acute leukemia (MPAL).
View Article and Find Full Text PDFbioRxiv
November 2024
Department of Medicine.
Mutations in the histone methyltransferase EZH2, particularly the Y641 hotspot mutation, have been implicated in hematologic malignancies, yet the effect of timing and cellular context on their oncogenic potential has remained unknown. In this study, we utilized a conditional allele with tissue-specific Cre drivers to investigate the effects of mutations at various stages of development, with a focus on the hematopoietic system. We found that ubiquitous heterozygous expression at birth, or conditional expression in hematopoietic or mesenchymal stem cells, led to decreased survival due to hematopoietic defects and bone marrow failure, with no evidence of malignancy.
View Article and Find Full Text PDFCancer is a major global health concern, with immune suppression hindering treatment. Immunotherapy, specifically immune checkpoint blockage on T cells, has revolutionized cancer treatment. T-cell exhaustion is an abnormal activation state that develops when continuous exposure to antigens, like cancer.
View Article and Find Full Text PDFPeerJ
November 2024
Neurosurgery Department, Jinzhou Central Hospital, Jinzhou, China.
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