Pre-B-cell leukemia transcription factor 1 (PBX1) (PBX1)

The Pre-B-cell leukemia transcription factor 1 (PBX1) is a nuclear protein belonging to the Three Aminoacid Loop Extension (TALE) homeodomain-containing family of transcription factors, specifically within the PBC subfamily (PBX1-4), that binds DNA and forms complexes with HOX and other homeobox proteins to regulate target gene expression. It plays crucial roles in embryonic development, including organ patterning, skeletal programming, and early hematopoiesis, where it supports hematopoietic stem cell self-renewal, B-cell and megakaryocyte differentiation, and maintenance of tissue homeostasis. PBX1 isoforms, such as PBX1a (brain/adult), PBX1b (embryonic), and PBX1d (T cells), exhibit tissue-specific expression and functions, including recruitment of chromatin regulators like SWI/SNF complexes. In disease, PBX1 is oncogenic when fused to E2A (TCF3-PBX1 via t(1;19) translocation), accounting for 5-10% of pediatric B-acute lymphoblastic leukemia (B-ALL) by inducing aberrant gene activation, proliferation, and leukemia progression; it is also implicated in solid tumors like breast and ovarian cancer, as well as myeloproliferative neoplasms through overexpression or copy number alterations. Aberrant PBX1 activity disrupts normal differentiation, promotes tumor growth, metastasis, invasion, and drug resistance, highlighting its dual role in development and oncogenesis, though no approved drugs directly target it.

Other names

Pre-B cell leukemia factor 1PBX homeobox family member