title: HMGB1 binds to the rs7903146 locus in TCF7L2 in human pancreatic islets.
abstract: The intronic SNP rs7903146 in the T-cell factor 7-like 2 gene (TCF7L2) is the common genetic variant most highly associated with Type 2 diabetes known to date. The risk T-allele is located in an open chromatin region specific to human pancreatic islets of Langerhans, thereby accessible for binding of regulatory proteins. The risk T-allele locus exhibits stronger enhancer activity compared to the non-risk C-allele. The aim of this study was to identify transcriptional regulators that bind the open chromatin region in the rs7903146 locus and thereby potentially regulate TCF7L2 expression and activity. Using affinity chromatography followed by Edman sequencing, we identified one candidate regulatory protein, i.e. high-mobility group protein B1 (HMGB1). The binding of HMGB1 to the rs7903146 locus was confirmed in pancreatic islets from human deceased donors, in HCT116 and in HEK293 cell lines using: (i) protein purification on affinity columns followed by Western blot, (ii) chromatin immunoprecipitation followed by qPCR and (iii) electrophoretic mobility shift assay. The results also suggested that HMGB1 might have higher binding affinity to the C-allele of rs7903146 compared to the T-allele, which was supported in vitro using Dynamic Light Scattering, possibly in a tissue-specific manner. The functional consequence of HMGB1 depletion in HCT116 and INS1 cells was reduced insulin and TCF7L2 mRNA expression, TCF7L2 transcriptional activity and glucose stimulated insulin secretion. These findings suggest that the rs7903146 locus might exert its enhancer function by interacting with HMGB1 in an allele dependent manner.
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Yuedan
authors: Y
authors: Zhou
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Nikolay
authors: N
authors: Oskolkov
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Liliya
authors: L
authors: Shcherbina
authors: Department of Biochemistry, University of Cambridge, CB2 1GA, Cambridge, UK.
authors: Joyce
authors: J
authors: Ratti
authors: Department of Biochemistry, University of Cambridge, CB2 1GA, Cambridge, UK.
authors: Kian-Hong
authors: KH
authors: Kock
authors: European Bioinformatics Institute, Functional Genomics, Hinxton, Cambridge CB10 1SD, UK.
authors: Jing
authors: J
authors: Su
authors: National Institute of Mental Health NIMH, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Brian
authors: B
authors: Martin
authors: Department of Physical Chemistry, Lund University, Lund, 22100, Sweden.
authors: Malin Zackrisson
authors: MZ
authors: Oskolkova
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Olga
authors: O
authors: Göransson
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Julie
authors: J
authors: Bacon
authors: Department of Physical Chemistry, Lund University, Lund, 22100, Sweden.
authors: Weimin
authors: W
authors: Li
authors: Department of Physical Chemistry, Lund University, Lund, 22100, Sweden.
authors: Saskia
authors: S
authors: Bucciarelli
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Corrado
authors: C
authors: Cilio
authors: European Bioinformatics Institute, Functional Genomics, Hinxton, Cambridge CB10 1SD, UK.
authors: Alvis
authors: A
authors: Brazma
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Bradley
authors: B
authors: Thatcher
authors: European Bioinformatics Institute, Functional Genomics, Hinxton, Cambridge CB10 1SD, UK.
authors: Johan
authors: J
authors: Rung
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Nils
authors: N
authors: Wierup
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Erik
authors: E
authors: Renström
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden.
authors: Leif
authors: L
authors: Groop
authors: Department of Clinical Sciences, CRC, Lund University, Malmö, 20502, Sweden. Electronic address: Ola.Hansson@med.lu.se.
authors: Ola
authors: O
authors: Hansson
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004247:DNA / Q000378:metabolism; D000067493:Dynamic Light Scattering; D056426:Genetic Loci; D045325:HCT116 Cells; D057809:HEK293 Cells; D024243:HMGB1 Protein / Q000378:metabolism*; D006801:Humans; D057446:Hydrodynamics; D007515:Islets of Langerhans / Q000378:metabolism*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015203:Reproducibility of Results; D058118:Transcription Factor 7-Like 2 Protein / Q000235:genetics*
chemical_list: D024243:HMGB1 Protein; D012333:RNA, Messenger; C544894:TCF7L2 protein, human; D058118:Transcription Factor 7-Like 2 Protein; D004247:DNA
keywords: Chromatin binding; HMGB1; TCF7L2; Type 2 diabetes