TY - JOUR
T1 - Structural and functional analysis of the differential effects of c-Jun and v-Jun on prolactin gene expression
AU - Farrow, Kathryn N.
AU - Bradford, Andrew P.
AU - Tentler, John J.
AU - Gutierrez-Hartmann, Arthur
PY - 2004/10
Y1 - 2004/10
N2 - The protooncogene c-Jun and its oncogenic isoform v-Jun are members of the activator protein 1 family of transcription factors that have been shown to have differential transcriptional effects that are both promoter specific and cell type specific. Previously, we have demonstrated that whereas c-Jun inhibits pituitary-specific rat prolactin (rPRL) promoter activity, expression of v-Jun stimulates the rPRL promoter in GH4 pituitary cells. In this report, we have conducted an extensive structure-function analysis of c-Jun vs. v-Jun to determine which regions of these proteins are responsible for their differential transcriptional effects in this pituitary model system. We show that isoform-specific responses are mediated by complex interactions between the δ-domain, serine 243, and the amino-terminal transcriptional activation domains. Thus, in contrast to previous reports, no single domain is responsible for the differential transcriptional activities of c-Jun and v-Jun. Mutation of c-Jun serine 243 to phenylalanine and replacement of the c-Jun amino terminus with the corresponding region from v-Jun, thereby removing the δ-domain, are necessary and sufficient to confer a functional switch from the c-Jun-inhibitory to the v-Jun-activating phenotype. Thus, we propose that isoform-specific subdomains in c-Jun and v-Jun dictate discrete interactions with distinct protein partners, which underlie the differential Jun-dependent transcriptional responses of the rPRL promoter.
AB - The protooncogene c-Jun and its oncogenic isoform v-Jun are members of the activator protein 1 family of transcription factors that have been shown to have differential transcriptional effects that are both promoter specific and cell type specific. Previously, we have demonstrated that whereas c-Jun inhibits pituitary-specific rat prolactin (rPRL) promoter activity, expression of v-Jun stimulates the rPRL promoter in GH4 pituitary cells. In this report, we have conducted an extensive structure-function analysis of c-Jun vs. v-Jun to determine which regions of these proteins are responsible for their differential transcriptional effects in this pituitary model system. We show that isoform-specific responses are mediated by complex interactions between the δ-domain, serine 243, and the amino-terminal transcriptional activation domains. Thus, in contrast to previous reports, no single domain is responsible for the differential transcriptional activities of c-Jun and v-Jun. Mutation of c-Jun serine 243 to phenylalanine and replacement of the c-Jun amino terminus with the corresponding region from v-Jun, thereby removing the δ-domain, are necessary and sufficient to confer a functional switch from the c-Jun-inhibitory to the v-Jun-activating phenotype. Thus, we propose that isoform-specific subdomains in c-Jun and v-Jun dictate discrete interactions with distinct protein partners, which underlie the differential Jun-dependent transcriptional responses of the rPRL promoter.
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U2 - 10.1210/me.2004-0113
DO - 10.1210/me.2004-0113
M3 - Article
C2 - 15231872
AN - SCOPUS:5044227585
SN - 0888-8809
VL - 18
SP - 2479
EP - 2490
JO - Molecular Endocrinology
JF - Molecular Endocrinology
IS - 10
ER -