Visit our Expo - Redox and Inflammation signaling 2012

Session XIV : Transcriptional and translational control Poster XIV, 46
Identification of a prostaglandin-responsive element in the Na,K-ATPase beta1 subunit
promoter which is regulated by cAMP and Ca2+ : Evidence for an interactive role of
CREB and Sp1
Keikantse Matlhagela, Maryann Borsick, Trivikram Rajkhowa, and Mary Taub*
Biochemistry Dept, 140 Farber Hall, State University of New York at Buffalo, Buffalo,
NY 14214, U.S.A., Email: *biochtau@buffalo.edu
The Na,K-ATPase, is a transmembrane protein responsible for maintaining electrochemical
gradients across the plasma membrane in all mammalian cells, a process which is subject to
regulation at the transcriptional and post-transcriptional levels. Included amongst physiologic
regulators in the kidney are prostaglandins. Previously, we presented evidence that
transcription of the Na,K-ATPase ß1 subunit is stimulated by PGE1, an effect mediated
through both cAMP and Ca2+ pathways. Transient transfection studies using 5’ deletion
mutants in the human ß1 subunit promoter indicate that a region located between –92 to –100
containing the sequence AGTCCCTGC (a Prostaglandin Response Element, or PGRE) is
required for eliciting the stimulatory effects of PGE1, 8Br-cAMP, Phorbol 12-myristate 13acetate
(TPA) and okadaic acid. Electrophoretic Mobility Shift Assays (EMSAs) indicate that
both the cAMP Regulatory Element Binding Protein (CREB) and Sp1 bind to this PGRE. The
involvement of the PGRE and Sp1 sites in regulation by PGE1 was further confirmed by
studies with a heterologous, and mutant promoters. The PGE1 stimulation was reduced when
the 2 GC boxes adjacent to the PGRE were translocated further upstream from the PGRE.
Also consistent with an interaction between CREB and Sp1 are our immunoprecipitation and
GST-pull down studies. In summary our results indicate the PGE1 induction involves
interactions between Sp1 and CREB which occur during the binding of these transcription
factors to a novel regulatory element, a PGRE, and an adjacent Sp1 site on the Na,K-ATPase
ß1 subunit promoter.
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