New role for Kruppel-like factor 14 as a transcriptional activator involved in the generation of signaling lipids.
Sphingosine kinase 1 (SK1) is an FGF-inducible gene responsible for generation of sphingosine-1-phosphate, a critical lipid signaling molecule implicated in diverse endothelial cell functions. In this study, we identified SK1 as a target of the canonical FGF2/FGF receptor 1 activation pathway in endothelial cells and sought to identify novel transcriptional pathways that mediate lipid signaling. Studies using the 1.9-kb SK1 promoter and deletion mutants revealed that basal and FGF2-stimulated promoter activity occurred through two GC-rich regions located within 633 bp of the transcription start site. Screening for GC-rich binding transcription factors that could activate this site demonstrated that KLF14, a gene implicated in obesity and the metabolic syndrome, binds to this region. Congruently, overexpression of KLF14 increased basal and FGF2-stimulated SK1 promoter activity by 3-fold, and this effect was abrogated after mutation of the GC-rich sites. In addition, KLF14 siRNA transfection decreased SK1 mRNA and protein levels by 3-fold. Congruently, SK1 mRNA and protein levels were decreased in livers from KLF14 knock-out mice. Combined, luciferase, gel shift, and chromatin immunoprecipitation assays showed that KLF14 couples to p300 to increase the levels of histone marks associated with transcriptional activation (H4K8ac and H3K14ac), while decreasing repressive marks (H3K9me3 and H3K27me3). Collectively, the results demonstrate a novel mechanism whereby SK1 lipid signaling is regulated by epigenetic modifications conferred by KLF14 and p300. Thus, this is the first description of the activity and mechanisms underlying the function of KLF14 as an activator protein and novel regulator of lipid signaling.
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and.
Thiago M
TM
de Assuncao
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and the Epigenomics Translational Program, Mayo Clinic Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota 55905.
Gwen
G
Lomberk
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and.
Sheng
S
Cao
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and.
Usman
U
Yaqoob
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and.
Angela
A
Mathison
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and.
Douglas A
DA
Simonetto
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and.
Robert C
RC
Huebert
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and the Epigenomics Translational Program, Mayo Clinic Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota 55905 urrutia.raul@mayo.edu.
Raul A
RA
Urrutia
From the Gastroenterology Research Unit, Departments of Biochemistry and Molecular Biology, Physiology and Biophysics, and Medicine and shah.vijay@mayo.edu.
Vijay H
VH
Shah
D000818:Animals; D002843:Chromatin / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D044127:Epigenesis, Genetic / Q000502:physiology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D057809:HEK293 Cells; D006657:Histones / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology*; D008099:Liver / Q000166:cytology; D008246:Lysophospholipids / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051703:Sp Transcription Factors / Q000235:genetics / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology; D000099157:Sphingosine Kinase
D002843:Chromatin; D016222:Fibroblast Growth Factor 2; D006657:Histones; D051741:Kruppel-Like Transcription Factors; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D051703:Sp Transcription Factors; D013110:Sphingosine; D000099157:Sphingosine Kinase; C417549:KLF14 protein, human; C558181:Klf14 protein, mouse; C060506:sphingosine 1-phosphate
Chromatin Histone Modification; Epigenetics; Fibroblast Growth Factor (FGF); Kruppel-like Factor (KLF); Sphingosine-1-phosphate (S1P)