Induction of dystrophin Dp71 expression during neuronal differentiation: opposite roles of Sp1 and AP2alpha in Dp71 promoter activity.
In this study, we delineated the molecular mechanisms that modulate Dp71 expression during neuronal differentiation, using the N1E-115 cell line. We demonstrated that Dp71 expression is up-regulated in response to cAMP-mediated neuronal differentiation of these cells, and that this induction is controlled at promoter level. Functional deletion analysis of the Dp71 promoter revealed that a 5'-flanking 159-bp DNA fragment that contains Sp1 and AP2 binding sites is necessary and sufficient for basal expression of this TATA-less promoter, as well as for its induction during neuronal differentiation. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that Sp1 and AP2alpha bind to their respective DNA elements within the Dp71 basal promoter. Overall, mutagenesis assays on the Sp1 and AP2 binding sites, over-expression of Sp1 and AP2alpha, as well as knock-down experiments on Sp1 and AP2alpha gene expression established that Dp71 basal expression is controlled by the combined action of Sp1 and AP2alpha, which act as activator and repressor, respectively. Furthermore, we demonstrated that induction of Dp71 expression in differentiated cells is the result of the maintenance of positive regulation exerted by Sp1, as well as of the loss of AP2alpha binding, which ultimately releases the promoter from repression.
Morales-Lázaro
Sara Luz
SL
Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del I.P.N., Avenida Instituto Politécnico Nacional 2508, México, D.F., México.
González-Ramírez
Ricardo
R
Gómez
Pablo
P
Tapia-Ramírez
Victor
V
de León
Mario Bermúdez
MB
Cisneros
Bulmaro
B
D000818:Animals; D001921:Brain / Q000166:cytology; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D047369:Chromatin Immunoprecipitation / Q000379:methods; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D016189:Dystrophin / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D050556:Fatty Acid-Binding Proteins; D016166:Free Radical Scavengers / Q000494:pharmacology; D007136:Immunoglobulins / Q000378:metabolism*; D051379:Mice; D016297:Mutagenesis, Site-Directed / Q000379:methods; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D014162:Transfection / Q000379:methods; D015854:Up-Regulation / Q000502:physiology; D001616:beta-Galactosidase / Q000378:metabolism
D004268:DNA-Binding Proteins; D016189:Dystrophin; C493411:Fabp4 protein, mouse; D050556:Fatty Acid-Binding Proteins; D016166:Free Radical Scavengers; D007136:Immunoglobulins; D034741:RNA, Small Interfering; C090698:SP1 antigen; C083115:activator protein-2 binding element; C085339:apo-dystrophin 1; D003994:Bucladesine; D052248:Nitric Oxide Synthase Type I; D015500:Chloramphenicol O-Acetyltransferase; D001616:beta-Galactosidase; D004121:Dimethyl Sulfoxide