The bZIP transcription factor Nrl stimulates rhodopsin promoter activity in primary retinal cell cultures

Rajan Kumar, Shiming Chen, David Scheurer, Qing Liang Wang, Elia Duh, Ching Hwa Sung, Alnawaz Rehemtulla, Anand Swaroop, Ruben Adler, Donald J. Zack

Research output: Contribution to journalArticlepeer-review

129 Scopus citations


In vitro DNA binding assays and transient transfection analysis with monkey kidney cells have implicated Nrl, a member of the Maf-Nrl subfamily of bZIP transcription factors, and the Nrl response element (NRE) in the regulation of rhodopsin expression. We have now further explored the role of the NRE and surrounding promoter elements. Using the yeast one-hybrid screen with integrated NRE and flanking DNA as bait, the predominant clone obtained was bovine Nrl. Recovery of truncated clones in the screen demonstrated that the carboxyl-terminal half of Nrl, which contains the basic and leucine zipper domains, is sufficient for DNA binding. To functionally dissect the rhodopsin promoter, transient expression studies with primary chick retinal cell cultures were performed. Deletion and mutation analyses identified two positive regulatory sequences: one between -40 and -84 base pairs (bp) and another between -84 and -130 bp. Activity of the -40 to -84 region was shown to be largely due to the NRE. On co-transfection with an NRL expression vector, there were 3-5-fold increases in the activity of rhodopsin promoter constructs containing an intact NRE but little or no effect with rhodopsin promoters containing a mutated or deleted NRE. Nrl was more effective than the related bZIP proteins, c-Fos and c-Jun, in stimulating rhodopsin promoter activity. The -84- to -130-bp region acted synergistically with the NRE to enhance both the level of basal expression and the degree of Nrl-mediated trans-activation. These studies support Nrl as a regulator of rhodopsin expression in vivo, identify an additional regulatory region just upstream of the NRE, and demonstrate the utility of primary retinal cell cultures for characterizing both the cis-acting response elements and trans-acting factors that regulate photoreceptor gene expression.

Original languageEnglish
Pages (from-to)29612-29618
Number of pages7
JournalJournal of Biological Chemistry
Issue number47
StatePublished - 1996


Dive into the research topics of 'The bZIP transcription factor Nrl stimulates rhodopsin promoter activity in primary retinal cell cultures'. Together they form a unique fingerprint.

Cite this