RESUMEN
A 2.8-kb cDNA encoding a new transcription factor (AP-2.2) has been cloned from mouse P19 embryonal carcinoma cells, in which the corresponding mRNA begins to accumulate 30 min after retinoic acid (RA) addition. The predicted protein is 449 amino acids long and exhibits approximately 65% overall identity with other AP-2-related proteins (human AP-2, mouse AP-2alpha and beta). A 96-amino-acid-long sequence, which is almost fully conserved between all these proteins, corresponds to the previously characterized human AP-2 DNA binding domain. Expression of AP-2.2 in Escherichia coli generated a protein that formed a specific complex with the AP-2 recognition site GCCN3GGC. AP-2.2 activated transcription from a reporter gene containing an AP-2 DNA binding site and acted synergistically with RARalpha to activate transcription from the CRABPII gene promoter. Transcriptional activation required the AP-2.2 amino-terminal region that contains a domain rich in proline and glutamine residues. The pattern of AP-2.2 expression in adult tissues, which is distinct from that of AP-2alpha, is essentially restricted to male and female gonads, to most if not all the squamous epithelia, and to several exocrine glands.
Asunto(s)
Proteínas de Unión al ADN/genética , Células Madre Neoplásicas/química , Factores de Transcripción/genética , Tretinoina/farmacología , Factores de Edad , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Clonación Molecular , ADN Complementario/fisiología , Proteínas de Unión al ADN/fisiología , Células Madre de Carcinoma Embrionario , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/fisiología , Immunoblotting , Hibridación in Situ , Ratones , Datos de Secuencia Molecular , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/fisiología , Regiones Promotoras Genéticas/genética , Receptores de Ácido Retinoico/genética , Transactivadores/fisiología , Factor de Transcripción AP-2 , Transcripción Genética/fisiologíaRESUMEN
The cDNA sequence of Stra7, a retinoic acid (RA)-inducible gene in P19 embryonal carcinoma (EC) cells, was determined. The deduced Stra7 protein contains a homeodomain highly similar to that of the previously described chicken CHox7 gene product, and is highly conserved during evolution, from hemichordates to vertebrates. The mouse Stra7 cDNA corresponds to the full-length form of the 77 bp homeodomain-encoding cDNA fragment which was previously cloned and termed MMoxA or Gbx-2. Reverse-transcriptase-PCR analysis revealed the presence of Stra7/Gbx-2 transcripts in the adult brain, spleen, and female genital tract, whereas no expression could be observed in heart, liver, lung, kidney, or testes. In situ hybridization analysis showed a restricted expression pattern of Stra7/Gbx-2 in the three primitive germ layers during gastrulation. Restricted expression was also detected in the pharyngeal arches. Subsequently, there were specific expression domains in the developing central nervous system, at the midbrain/hindbrain boundary and later in the cerebellum anlage, in certain rhombomeres, in dorsal regions of the spinal cord, and in the developing dorsal thalamus and corpus striatum.