Human Epistatic Interaction Controls IL7R Splicing and Increases Multiple Sclerosis Risk.
Multiple sclerosis (MS) is an autoimmune disorder where T cells attack neurons in the central nervous system (CNS) leading to demyelination and neurological deficits. A driver of increased MS risk is the soluble form of the interleukin-7 receptor alpha chain gene (sIL7R) produced by alternative splicing of IL7R exon 6. Here, we identified the RNA helicase DDX39B as a potent activator of this exon and consequently a repressor of sIL7R, and we found strong genetic association of DDX39B with MS risk. Indeed, we showed that a genetic variant in the 5' UTR of DDX39B reduces translation of DDX39B mRNAs and increases MS risk. Importantly, this DDX39B variant showed strong genetic and functional epistasis with allelic variants in IL7R exon 6. This study establishes the occurrence of biological epistasis in humans and provides mechanistic insight into the regulation of IL7R exon 6 splicing and its impact on MS risk.
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Center for RNA Biology, Duke University, Durham, NC 27710, USA; Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Gaddiel
G
Galarza-Muñoz
Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
Farren B S
FBS
Briggs
Center for RNA Biology, Duke University, Durham, NC 27710, USA.
Irina
I
Evsyukova
Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Geraldine
G
Schott-Lerner
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Edward M
EM
Kennedy
Department of Immunology, Duke University Durham, NC 27710, USA; Department of Surgery, Duke University Durham, NC 27710, USA.
Tinashe
T
Nyanhete
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Liuyang
L
Wang
Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA.
Laura
L
Bergamaschi
Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Steven G
SG
Widen
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Immunology, Duke University Durham, NC 27710, USA; Department of Surgery, Duke University Durham, NC 27710, USA.
Georgia D
GD
Tomaras
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Duke University Medical Center; Durham, NC 27710, USA.
Dennis C
DC
Ko
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Center for RNA Biology, Duke University, Durham, NC 27710, USA; Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Shelton S
SS
Bradrick
Division of Epidemiology, School of Public Health, University of California Berkeley, Berkeley, CA 94720, USA.
Lisa F
LF
Barcellos
Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA; Department of Neurology, Duke University Medical Center, Durham, NC 27710, USA. Electronic address: simon.gregory@duke.edu.
Simon G
SG
Gregory
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Center for RNA Biology, Duke University, Durham, NC 27710, USA; Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA. Electronic address: maragarc@utmb.edu.
Mariano A
MA
Garcia-Blanco
D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D004843:Epistasis, Genetic; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D053699:Interleukin-7 Receptor alpha Subunit / Q000235:genetics*; D009103:Multiple Sclerosis / Q000235:genetics; D014176:Protein Biosynthesis; D012326:RNA Splicing; D034741:RNA, Small Interfering / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology
C000620371:IL7R protein, human; D053699:Interleukin-7 Receptor alpha Subunit; D034741:RNA, Small Interfering; C487886:DDX39B protein, human; D053487:DEAD-box RNA Helicases
DDX39B; IL7R; alternative splicing; autoimmune disorders; epistasis; genetic association; multiple sclerosis