Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Phospholamban (PLN), a pentameric protein composed of 52 amino acids subunits, is a major substrate for the cAMP-dependent protein kinase in sarcoplasmic reticulum. The expression of PLN is restricted to muscle cells expressing SERCA2 (cardiac, slow-twitch skeletal, and smooth muscles). We identified the regions of SERCA2 that interact directly with phospholamban. A 5'-upstream region of the phospholamban gene was analyzed to define the transcriptional regulation. Using a series of deletion constructs, we demonstrated that the region from -96 to -78 base pairs containing the CCAAT sequence is essential for transcription of this gene. This region specifically bound to nuclear proteins extracted from rat hearts, and gel shift assays using competitive oligonucleotides, antibodies and recombinant proteins showed that this region binds to the NF-YA and NF-YB among the CCAAT motif-binding proteins. This region-dependent transcription in cardiac myocytes transfected with antisense cDNAs encoding NF-YA and NF-YB was decreased to approximately 50% of that seen in cells transfected with the same sense cDNAs. We therefore conclude that the region from -96 to -78 base pairs plays a critical role in expression of the phospholamban gene which is regulated by binding of the nuclear protein NF-Y.

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Presentation Number SAtada0477
Keywords: phospholamban, SERCA2, NF-Y, Cardiac myocytes