RESUMEN
The serum response factor (SRF) activates expression of several genes in response to growth factors present in serum. SRF also regulates the expression of tissue-specific genes, including those in vertebrate muscles. An SRF-binding site (CArG box) present in the Artemia franciscana Actin403 promoter was shown to be necessary for transcriptional activity in cultured cells from Drosophila melanogaster and mammals. This DNA region bound mammalian and Drosophila SRFs in vitro and mediated transcriptional activation of the Actin403 promoter in response to serum, phorbol esters and lysophosphatidic acid in transfected cultured mammalian cells. Mutations in the CArG box greatly reduced promoter activity and stimulation by extracellular compounds.
Asunto(s)
Actinas/genética , Artemia/genética , Artemia/metabolismo , Proteínas de Unión al ADN/metabolismo , Proteínas Nucleares/metabolismo , Regiones Promotoras Genéticas , Células 3T3 , Animales , Secuencia de Bases , Sitios de Unión/genética , Línea Celular , ADN/genética , ADN/metabolismo , Regulación de la Expresión Génica , Ratones , Datos de Secuencia Molecular , Factor de Respuesta Sérica , Transcripción Genética , TransfecciónRESUMEN
Complementary DNA clones have been isolated from the crustacean Artemia franciscana coding for a serum response factor (SRF)-homologue that is more than 96% identical to human and Drosophila melanogaster SRFs in their MADS boxes. The SRF homologue is expressed in ectodermal tissues, as determined by in situ hybridization experiments. A SRF-binding site has been identified in the promoter region of the Actin403 gene that is also expressed in ectodermal tissues, in accordance with its transcriptional regulation by the SRF homologue. The mRNA coding for A. franciscana SRF is present at similar levels in cryptobiotic encysted embryos and in developing nauplii. However, there is a significant increase in CArG-binding activity at the later developmental stage, indicating a postranscriptional regulation of SRF during A. franciscana embryonic development.