title: Glucose regulation of dipeptidyl peptidase IV gene expression is mediated by hepatocyte nuclear factor-1alpha in epithelial intestinal cells.
abstract: 1. Dipeptidyl peptidase IV (DPP-IV) is a new drug target in the treatment of Type 2 diabetes. Dipeptidyl peptidase IV enzyme activity is significantly altered in Type 2 diabetic patients with hyperglycaemia, but the underlying molecular mechanisms remain unclear. 2. The first aim of the present study was to clarify whether glucose regulates DPP-IV enzyme activity. To address this, DPP-IV gene expression and enzyme activity were measured in Caco2 cells cultured in the presence of low (2.5 mmol/L) or high (16.7 mmol/L) concentrations of glucose. We observed that high glucose inhibited DPP-IV gene expression and enzyme activity. 3. The second aim of the present study was to investigate whether hepatocyte nuclear factor (HNF)-1alpha contributes to glucose regulation of DPP-IV gene expression. To explore this question, associations between the gene expression of DPP-IV and HNF-1alpha were examined in Caco-2 cells cultured in the presence of low (2.5 mmol/L) or high (16.7 mmol/L) glucose. We found that the pattern of glucose-regulated DPP-IV gene expression is similar to that of HNF-1alpha. Moreover, to elucidate whether glucose regulation of DPP-IV gene expression is affected when HNF-1alpha is inhibited, we produced two stable cell lines in which a dominant-negative mutant HNF-1alphaR271G or basic vectors were stably expressed. We found that glucose regulation of DPP-IV gene expression was compromised in HNF-1alphaR271G cells, but was well maintained in basic vector cells. 4. These results suggest that glucose regulation of DPP-IV gene expression is mediated by HNF-1alpha.
authors.affiliation: Laboratory of Metabolism, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Ning
authors.initials: N
authors.lastname: Gu
authors.forename: Mariko
authors.initials: M
authors.lastname: Tsuda
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Matsunaga
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Adachi
authors.forename: Koichiro
authors.initials: K
authors.lastname: Yasuda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishihara
authors.forename: Kinsuke
authors.initials: K
authors.lastname: Tsuda
mesh_terms: D018938:Caco-2 Cells; D018819:Dipeptidyl Peptidase 4 / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D005947:Glucose / Q000502:physiology*; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D051538:Hepatocyte Nuclear Factor 1-alpha; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4; D005947:Glucose