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Human NCU-G1 can function as a transcription factor and as a nuclear receptor co-activator.

Steffensen KR, Bouzga M, Skjeldal F, Kasi C, Karahasan A, Matre V, Bakke O, Guérin S, Eskild W - BMC Mol. Biol. (2007)

Bottom Line: NCU-G1 was found to be a highly conserved nuclear protein rich in proline with a molecular weight of approximately 44 kDa.In man, NCU-G1 was found to be widely expressed at the mRNA level with especially high levels detected in prostate, liver and kidney.NCU-G1 was found to activate transcription from this promoter and required presence of the footprint 1 element.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular Biosciences, University of Oslo, Norway. knut.steffensen@biosci.ki.se

ABSTRACT

Background: Novel, uncharacterised proteins represent a challenge in biochemistry and molecular biology. In this report we present an initial functional characterization of human kidney predominant protein, NCU-G1.

Results: NCU-G1 was found to be a highly conserved nuclear protein rich in proline with a molecular weight of approximately 44 kDa. It is localized on chromosome 1 and consists of 6 exons. Analysis of the amino acid sequence revealed no known transcription activation domains or DNA binding regions, however, four nuclear receptor boxes (LXXLL), and four SH3-interaction motives in addition to numerous potential phosphorylation sites were found. Two nuclear export signals were identified, but no nuclear localization signal. In man, NCU-G1 was found to be widely expressed at the mRNA level with especially high levels detected in prostate, liver and kidney. Electrophoretic mobility shift analysis showed specific binding of NCU-G1 to an oligonucleotide representing the footprint 1 element of the human cellular retinol-binding protein 1 gene promoter. NCU-G1 was found to activate transcription from this promoter and required presence of the footprint 1 element. In transiently transfected Drosophila Schneider S2 cells, we demonstrated that NCU-G1 functions as a co-activator for ligand-activated PPAR-alpha, resulting in an increased expression of a CAT reporter gene under control of the peroxisome proliferator-activated receptor-alpha responsive acyl-CoA oxidase promoter.

Conclusion: We propose that NCU-G1 is a dual-function protein capable of functioning as a transcription factor as well as a nuclear receptor co-activator.

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Analysis of the NCU-G1 amino acid sequence. Panel A: Comparison of deduced NCU-G1 amino acid sequences from various species. Totally conserved amino acids are shown against a black background. Highly conserved amino acids are shown against a grey background. The positions of conserved prolines are marked with black bullets. Panel B: Potential functional motifs in human NCU-G1.
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Figure 1: Analysis of the NCU-G1 amino acid sequence. Panel A: Comparison of deduced NCU-G1 amino acid sequences from various species. Totally conserved amino acids are shown against a black background. Highly conserved amino acids are shown against a grey background. The positions of conserved prolines are marked with black bullets. Panel B: Potential functional motifs in human NCU-G1.

Mentions: In order to study these proteins in more detail, we used the One-Hybrid cloning strategy to clone their corresponding cDNAs from an expression library prepared from human placenta. The FP1 element was used as bait after some modifications to avoid recognition by NF1 and Sp1. Screening of the placenta expression library resulted in isolation of three unique clones one of which contained an insert of 1.7 kb. DNA sequencing of this clone revealed an open reading frame of 1221 base pairs yielding a protein of 406 amino acids (figure 1A). Blast analysis identified it as kidney predominant protein, alias NCU-G1 or C1orf85 homologous to the previously published mouse NCU-G1 [20]. A search of the human genome database showed that NCU-G1 is located on chromosome 1, 1q23.1, locus 112770, and has an open reading frame spanning 6 exons. No human homologues were identified, indicating that NCU-G1 is unique.


Human NCU-G1 can function as a transcription factor and as a nuclear receptor co-activator.

Steffensen KR, Bouzga M, Skjeldal F, Kasi C, Karahasan A, Matre V, Bakke O, Guérin S, Eskild W - BMC Mol. Biol. (2007)

Analysis of the NCU-G1 amino acid sequence. Panel A: Comparison of deduced NCU-G1 amino acid sequences from various species. Totally conserved amino acids are shown against a black background. Highly conserved amino acids are shown against a grey background. The positions of conserved prolines are marked with black bullets. Panel B: Potential functional motifs in human NCU-G1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2233640&req=5

Figure 1: Analysis of the NCU-G1 amino acid sequence. Panel A: Comparison of deduced NCU-G1 amino acid sequences from various species. Totally conserved amino acids are shown against a black background. Highly conserved amino acids are shown against a grey background. The positions of conserved prolines are marked with black bullets. Panel B: Potential functional motifs in human NCU-G1.
Mentions: In order to study these proteins in more detail, we used the One-Hybrid cloning strategy to clone their corresponding cDNAs from an expression library prepared from human placenta. The FP1 element was used as bait after some modifications to avoid recognition by NF1 and Sp1. Screening of the placenta expression library resulted in isolation of three unique clones one of which contained an insert of 1.7 kb. DNA sequencing of this clone revealed an open reading frame of 1221 base pairs yielding a protein of 406 amino acids (figure 1A). Blast analysis identified it as kidney predominant protein, alias NCU-G1 or C1orf85 homologous to the previously published mouse NCU-G1 [20]. A search of the human genome database showed that NCU-G1 is located on chromosome 1, 1q23.1, locus 112770, and has an open reading frame spanning 6 exons. No human homologues were identified, indicating that NCU-G1 is unique.

Bottom Line: NCU-G1 was found to be a highly conserved nuclear protein rich in proline with a molecular weight of approximately 44 kDa.In man, NCU-G1 was found to be widely expressed at the mRNA level with especially high levels detected in prostate, liver and kidney.NCU-G1 was found to activate transcription from this promoter and required presence of the footprint 1 element.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular Biosciences, University of Oslo, Norway. knut.steffensen@biosci.ki.se

ABSTRACT

Background: Novel, uncharacterised proteins represent a challenge in biochemistry and molecular biology. In this report we present an initial functional characterization of human kidney predominant protein, NCU-G1.

Results: NCU-G1 was found to be a highly conserved nuclear protein rich in proline with a molecular weight of approximately 44 kDa. It is localized on chromosome 1 and consists of 6 exons. Analysis of the amino acid sequence revealed no known transcription activation domains or DNA binding regions, however, four nuclear receptor boxes (LXXLL), and four SH3-interaction motives in addition to numerous potential phosphorylation sites were found. Two nuclear export signals were identified, but no nuclear localization signal. In man, NCU-G1 was found to be widely expressed at the mRNA level with especially high levels detected in prostate, liver and kidney. Electrophoretic mobility shift analysis showed specific binding of NCU-G1 to an oligonucleotide representing the footprint 1 element of the human cellular retinol-binding protein 1 gene promoter. NCU-G1 was found to activate transcription from this promoter and required presence of the footprint 1 element. In transiently transfected Drosophila Schneider S2 cells, we demonstrated that NCU-G1 functions as a co-activator for ligand-activated PPAR-alpha, resulting in an increased expression of a CAT reporter gene under control of the peroxisome proliferator-activated receptor-alpha responsive acyl-CoA oxidase promoter.

Conclusion: We propose that NCU-G1 is a dual-function protein capable of functioning as a transcription factor as well as a nuclear receptor co-activator.

Show MeSH