ISL1 directly regulates FGF10 transcription during human cardiac outflow formation.
The LIM homeodomain gene Islet-1 (ISL1) encodes a transcription factor that has been associated with the multipotency of human cardiac progenitors, and in mice enables the correct deployment of second heart field (SHF) cells to become the myocardium of atria, right ventricle and outflow tract. Other markers have been identified that characterize subdomains of the SHF, such as the fibroblast growth factor Fgf10 in its anterior region. While functional evidence of its essential contribution has been demonstrated in many vertebrate species, SHF expression of Isl1 has been shown in only some models. We examined the relationship between human ISL1 and FGF10 within the embryonic time window during which the linear heart tube remodels into four chambers. ISL1 transcription demarcated an anatomical region supporting the conserved existence of a SHF in humans, and transcription factors of the GATA family were co-expressed therein. In conjunction, we identified a novel enhancer containing a highly conserved ISL1 consensus binding site within the FGF10 first intron. ChIP and EMSA demonstrated its direct occupation by ISL1. Transcription mediated by ISL1 from this FGF10 intronic element was enhanced by the presence of GATA4 and TBX20 cardiac transcription factors. Finally, transgenic mice confirmed that endogenous factors bound the human FGF10 intronic enhancer to drive reporter expression in the developing cardiac outflow tract. These findings highlight the interest of examining developmental regulatory networks directly in human tissues, when possible, to assess candidate non-coding regions that may be responsible for congenital malformations.
Department of Cell Biology, Duke Medical Center, Durham, North Carolina, United States of America.
Christelle
C
Golzio
Emmanuelle
E
Havis
Philippe
P
Daubas
Gregory
G
Nuel
Candice
C
Babarit
Arnold
A
Munnich
Michel
M
Vekemans
Stéphane
S
Zaffran
Stanislas
S
Lyonnet
Heather C
HC
Etchevers
D000818:Animals; D001483:Base Sequence; D019295:Computational Biology; D024202:Electrophoretic Mobility Shift Assay; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D051526:Fibroblast Growth Factor 10 / Q000235:genetics* / Q000378:metabolism; D050991:GATA4 Transcription Factor / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D006321:Heart / Q000196:embryology*; D006614:Hindlimb / Q000196:embryology / Q000378:metabolism; D006801:Humans; D007438:Introns / Q000235:genetics; D060850:LIM-Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D038081:Organogenesis / Q000235:genetics*; D011247:Pregnancy; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
C496463:FGF10 protein, human; D051526:Fibroblast Growth Factor 10; D050991:GATA4 Transcription Factor; D060850:LIM-Homeodomain Proteins; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; C420984:TBX20 protein, human; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1