HOXA9
Description
The HOXA9 (homeobox A9) is a protein-coding gene located on chromosome 7.
HOXA9, encoded by the HOXA9 gene, is a transcription factor that plays a crucial role in embryonic development and hematopoiesis. It belongs to the homeobox gene family, which is responsible for establishing the body plan of animals. HOXA9 is specifically expressed in hematopoietic stem cells (HSCs) and its expression decreases as cells differentiate and mature. HOXA9 is highly similar to the Abd-B gene in Drosophila and its dysregulation is linked to acute myeloid leukemia. A translocation event fusing HOXA9 with the NUP98 gene has been implicated in the development of myeloid leukemia. HOXA9's critical role in hematopoiesis is further emphasized by its differential expression across erythrocyte lineage stages and the reduction in circulating common myeloid progenitor cells observed in HOXA9 knockout mice.
HOXA9 is a sequence-specific transcription factor that plays a critical role in development by establishing positional identities along the body's anterior-posterior axis. During inflammation, HOXA9 is essential for inducing the expression of E-selectin (SELE) and vascular cell adhesion molecule 1 (VCAM1) on the surface of endothelial cells, contributing to the inflammatory response. HOXA9 promotes the export of mRNA from the nucleus by positively regulating the activity of eukaryotic translation initiation factor 4E (EIF4E). It also enhances the translation efficiency of ornithine decarboxylase (ODC) mRNA in the cytoplasm by competing with factors like PRH, which suppress EIF4E activity. HOXA9 transiently interacts with protein arginine methyltransferase 5 (PRMT5) in TNF-alpha-stimulated endothelial cells.
HOXA9 is also known as ABD-B, HOX1, HOX1.7, HOX1G.
