BAC transgenic zebrafish reveal hypothalamic enhancer activity around obesity associated SNP rs9939609 within the human FTO gene.
Single Nucleotide Polymorphisms in FTO intron 1 have been associated with obesity risk, leading to the hypothesis that FTO is the obesity-related gene. However, other studies have shown that the FTO gene is part of the regulatory domain of the neighboring IRX3 gene and that enhancers in FTO intron 1 regulate IRX3. While Irx3 activity was shown to be necessary in the hypothalamus for the metabolic function of Irx3 in mouse, no enhancers with hypothalamic activity have been demonstrated in the risk-associated region within FTO. In order to identify potential enhancers at the human FTO locus in vivo, we tested regulatory activity in FTO intron 1 using BAC transgenesis in zebrafish. A minimal gata2 promoter-GFP cassette was inserted 1.3 kb upstream of the obesity associated SNP rs9939609 in a human FTO BAC plasmid. In addition to the previously identified expression domains in notochord and kidney, human FTO BAC:GFP transgenic zebrafish larvae expressed GFP in the ventral posterior tuberculum, the posterior hypothalamus and the anterior brainstem, which are also expression domains of zebrafish irx3a. In contrast, an in-frame insertion of a GFP cassette at the FTO start codon resulted in weak ubiquitous GFP expression indicating that the promoter of FTO does likely not react to enhancers located in the obesity risk-associated region.
Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.|Department of Physiology, School of Medicine, University of Sydney, Australia.
Silke
S
Rinkwitz
Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.
Fan-Suo
FS
Geng
Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.
Elizabeth
E
Manning
Neural Circuits and Behavior Group, Uni Research AS, Bergen, Norway.
Maximiliano
M
Suster
Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan.
Koichi
K
Kawakami
Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.|Department of Physiology, School of Medicine, University of Sydney, Australia.
Thomas S
TS
Becker
D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D020022:Genetic Predisposition to Disease / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007031:Hypothalamus / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007438:Introns / Q000235:genetics; D007814:Larva / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D009765:Obesity / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
D018398:Homeodomain Proteins; D011506:Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; D049452:Green Fluorescent Proteins; D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; C526492:FTO protein, human
GWAS; genetics; genomics; mammal; organism; tissue