Repression of A TAF(II)32 isoform as part of a program of genes regulated during Mpl ligand-induced megakaryocyte differentiation

Circulating platelets, essential for thrombosis and hemostasis, originate f rom megakaryocytes. Megakaryocyte growth, differentiation and survival proc esses are regulated by the c-Mpl receptor ligand. In the current study we u sed differential display to identify part of the program of genes regulated during Mpl ligand-induced murine megakaryocyte differentiation. Several of the genes, including the retinoblastoma binding protein p84, were found to be induced, while others were repressed. One such repressed gene was ident ified as a TATA-binding protein (TBP)-Associated Factor (TAF) family member , TAF(II)32, previously reported to be upregulated during apoptosis, Our an alysis of various cell types suggested that the previously identified speci es homologs, human TAF(II)32 and murine TAF(II)32, are in fact different is oforms, which We propose to re-name TAF(II)32 alpha and TAF(II)32 beta, res pectively. Only the TAF(II)32 beta isoform is regulated during Mpl ligand-i nduced megakaryocyte differentiation, which suggests individual roles for t he two forms. (C) 1999 Academic Press.