RESUMO
Casein gene expression is induced in the rabbit mammary gland by prolactin (PRL). alpha s1-casein is the major casein secreted into milk. In order to define the position of the DNA sequences involved in the control of rabbit alpha s1-casein gene regulation by PRL, chimeric genes were constructed between upstream regions of the rabbit alpha s1-casein gene and the chloramphenicol acetyl transferase (CAT) reporter gene. A series of 5'-deleted fusion genes was obtained by nuclease digestion of the alpha s1-casein gene upstream region. These gene constructs were transfected into rabbit primary mammary cells, or cotransfected in CHO cells with the plasmid coding for the rabbit mammary receptor (PRL-R). A regulatory region has been located between nt -3768 and -3155. This region enhances the prolactin induced promoter activity of the alpha s1-casein gene. It might possess or cooperate with prolactin responsive elements located further downstream in the alpha s1-casein gene.
Assuntos
Caseínas/genética , Elementos Facilitadores Genéticos , Regulação da Expressão Gênica/efeitos dos fármacos , Prolactina/farmacologia , Regiões Promotoras Genéticas/efeitos dos fármacos , Animais , Células CHO , Caseínas/biossíntese , Células Cultivadas , Cricetinae , Feminino , Genes Sintéticos , Glândulas Mamárias Animais/citologia , Gravidez , Coelhos/genética , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genéticaRESUMO
Whey acidic protein gene transcription is induced in the mammary gland under the influence of lactogenic hormones: prolactin, insulin and cortisol. The rabbit WAP gene has already been isolated and sequenced in a previous work. In the present study, we have evaluated the role of the 5' flanking region of the rabbit WAP gene in the transcriptional regulation of the WAP gene by using a reporter CAT gene. Chimeric genes containing the upstream region of the WAP gene have been linked to the bacterial CAT gene and transfected into rabbit primary mammary cells. The results reported here show that two regions carrying important regulatory elements of the rabbit WAP gene are located between -6300 and -3000 bp, and between -3000 and -1800 bp upstream from the WAP transcription start point, respectively. The contribute to the high level of expression of the rabbit WAP gene in the mammary cell.
