POU domain transcription factors in embryonic development

Molecular Biology Reports -     

The POU transcription factor Oct-1 represses virus-induced interferon A gene expression

Alpha interferon (IFN-alpha) and IFN-beta are able to interfere with viral infection. They exert a vast array of biologic functions, including growth arrest, cell differentiation, and immune system regulation. This regulation extends from innate immunity to cellular and humoral adaptive immune responses. A strict control of expression is needed to prevent detrimental effects of unregulated IFN. Multiple IFN-A subtypes are coordinately induced in human and mouse cells infected by virus and exhibit differences in expression of their individual mRNAs. We demonstrated that the weakly expressed IFN-A11 gene is negatively regulated after viral infection, due to a distal negative regulatory element, binding homeoprotein pituitary homeobox 1 (Pitx1). Here we show that the POU protein Oct-1 binds in vitro and in vivo to the IFN-A11 promoter and represses IFN-A expression upon interferon regulatory factor overexpression. Furthermore, we show that Oct-1-deficient MEFs exhibit increased in vivo IFN-A gene expression and increased antiviral activity. Finally, the IFN-A expression pattern is modified in Oct-1-deficient MEFs. The broad representation of effective and potent octamer-like sequences within IFN-A promoters suggests an important role for Oct-1 in IFN-A regulation.     

Developmental expression of the POU transcription factor qBrn-2 during somitic myogenesis in quail

We prepared a specific antiserum to the qBrn-2 protein and examined the developmental distribution of this protein during quail somitic myogenesis. In contrast to its mammalian homolog N-Oct-3, qBrn-2 exhibited an impressive spatio-temporal profile in somitic myogenesis, in addition to the orthodox expression observed in the developing neural tube. In somites, qBrn-2 was expressed in the outer epithelial cells, but not in the core cells. During the somite differentiation, qBrn-2 expression was enhanced and restricted to myotome. The location of qBrn-2 expression seemed to overlap with that of myf5 and myoD in myotome. However, in cells that just began to express myf5 or myoD, qBrn-2 expression was not obvious. As embryonic development proceeded, qBrn-2 positive cells in myotome migrated dorsally and ventrally, and qBrn-2 expression was still observed at dorsal and ventral muscle masses in the forelimb. On the basis of our observations, it seems that qBrn-2 may play important roles in the determination, differentiation and migration of muscle precursor cells, in addition to its known roles in neurogenesis.