Human Krüppel-like factor 11 differentially regulates human insulin promoter activity in β-cells and non-β-cells via p300 and PDX1 through the regulatory sites A3 and CACCC box.
Human Krüppel-like factor 11 (hKLF11) has been characterised to both activate and inhibit human insulin promoter (hInsP) activity. Since KLF11 is capable to differentially regulate genes dependent on recruited cofactors, we investigated the effects of hKLF11 on cotransfected hInsP in both β-cells and non-β-cells. hKLF11 protein interacts with hp300 but not with hPDX1. Overexpressed hKLF11 stimulates PDX1-transactivation of hInsP in HEK293 non-β-cells, but confers inhibition in INS-1E β-cells. Both hKLF11 functions can be neutralised by the p300 inhibitor E1A, increased hp300 levels (INS-1E), dominant negative (DN)-PDX1 and by mutation of the PDX1 binding site A3 or the CACCC box. In summary, hKLF11 differentially regulates hInsP activity depending on the molecular context via modulation of p300:PDX1 interactions with the A3 element and CACCC box. We postulate that KLF11 has a role in fine-tuning insulin transcription in certain cellular situations rather than representing a major transcriptional activator or repressor of the insulin gene.
Division of Endocrinology and Diabetology, Department of Internal Medicine II, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany.
Nikolaos
N
Perakakis
Despoina
D
Danassi
Marcus
M
Alt
Eleni
E
Tsaroucha
Amir E
AE
Mehana
Natalie
N
Rimmer
Katharina
K
Laubner
Haiyan
H
Wang
Claes B
CB
Wollheim
Jochen
J
Seufert
Günter
G
Päth
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000502:physiology*; D002460:Cell Line; D050881:E1A-Associated p300 Protein / Q000378:metabolism*; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000235:genetics*; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D012097:Repressor Proteins / Q000502:physiology*; D020218:Response Elements; D015534:Trans-Activators / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D051017:Apoptosis Regulatory Proteins; D018797:Cell Cycle Proteins; D018398:Homeodomain Proteins; D007328:Insulin; C115117:KLF11 protein, human; D012097:Repressor Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human