Transcriptional regulation of pig lactase-phlorizin hydrolase: involvement of HNF-1 and FREACs.
OBJECTIVE
One-kilobase sequence of the upstream fragment of the pig lactase-phlorizin hydrolase gene has been shown to control small intestinal-specific expression and postweaning decline of lactase-phlorizin hydrolase in transgenic mice. The aim of this study was to identify the regulatory DNA elements and transcription factors controlling lactase-phlorizin hydrolase expression.


METHODS
The activity of different lactase-phlorizin hydrolase promoter fragments was investigated by transfection experiments using Caco-2 cells. Electrophoretic mobility shift assays and supershift analyses were used to characterize the interaction between intestinal transcription factors and the identified regulatory elements.


RESULTS
Functional analysis revealed three previously undescribed regulatory regions in the lactase-phlorizin hydrolase promoter: a putative enhancer between -894 and -798 binding hepatocyte nuclear factor (HNF)-1 at position -894 to -880; a repressor-binding element between -278 to -264 to which an HNF-3-like factor is able to bind; and an element between -178 to -164 that binds an activating transcription factor.


CONCLUSIONS
Identification of three new regulatory regions and HNF-1 and HNF-3-like transcription factor as players in the regulation of lactase-phlorizin hydrolase gene transcription has an impact on the understanding of the molecular mechanisms behind age-dependent, tissue-specific, differentiation-dependent, and regional regulation of expression in the intestine.
Spodsberg
N
N
Department of Medical Biochemistry and Genetics, Biochemical Laboratory C, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
Troelsen
J T
JT
Carlsson
P
P
Enerbäck
S
S
Sjöström
H
H
Norén
O
O
D000818:Animals; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D018938:Caco-2 Cells; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000502:physiology*; D051858:Forkhead Transcription Factors; D015971:Gene Expression Regulation, Enzymologic; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D010694:Lactase-Phlorizin Hydrolase / Q000235:genetics*; D009687:Nuclear Proteins / Q000502:physiology; D011401:Promoter Regions, Genetic; D013552:Swine; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; C486413:FOXF2 protein, human; D051858:Forkhead Transcription Factors; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; C114562:LUN protein, vertebrate; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D010694:Lactase-Phlorizin Hydrolase