Functional dissection of the HNF-1alpha transcription factor: a study on nuclear localization and transcriptional activation.
Hepatocyte nuclear factor-1alpha (HNF-1alpha) is a homeodomain-containing transcription factor regulating the expression of liver and pancreas-specific genes. Mutations in the HNF-1alpha-encoding gene TCF1 cause maturity-onset diabetes of the young, type 3 (MODY3). These mutations may affect nuclear import or reduce the ability of HNF-1alpha to stimulate transcription. We performed a functional dissection of HNF-1alpha, attempting both to define its nuclear localization signals (NLSs) and to identify important elements of the Cterminal transactivation domain. Three HNF-1alpha regions, A (amino acids 158-171), B (197-205), and C (271-282), highly similar to consensus NLSs, were studied by immunolocalization in HeLa cells. Region B could be identified as the most critical for correct nuclear localization. Deletion of two subregions (amino acids 398-470 and 544-631, respectively) in the HNF-1alpha C-terminal transactivation domain, resulted in the greatest reduction in stimulation of transcription compared to wild-type protein. However, this domain probably consists of many elements that work in concert to give the full transactivation potential of the protein.
Bjørkhaug
Lise
L
Section for Medical Genetics and Molecular Medicine, University of Bergen, Bergen, Norway.
Bratland
André
A
Njølstad
Pål Rasmus
PR
Molven
Anders
A
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D002451:Cell Compartmentation; D017930:Genes, Reporter; D006367:HeLa Cells; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D019913:Nuclear Localization Signals / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D011993:Recombinant Fusion Proteins; C054562:yellow fluorescent protein, Bacteria