Hypomorphic nuclear factor-kappaB essential modulator mutation database and reconstitution system identifies phenotypic and immunologic diversity.
BACKGROUND
Human hypomorphic nuclear factor-kappaB essential modulator (NEMO) mutations cause diverse clinical and immunologic phenotypes, but understanding of their scope and mechanistic links to immune function and genotype is incomplete.


OBJECTIVE
We created and analyzed a database of hypomorphic NEMO mutations to determine the spectrum of phenotypes and their associated genotypes and sought to establish a standardized NEMO reconstitution system to obtain mechanistic insights.


METHODS
Phenotypes of 72 individuals with NEMO mutations were compiled. NEMO L153R and C417R were investigated further in a reconstitution system. TNF-alpha or Toll-like receptor (TLR)-5 signals were evaluated for nuclear factor-kappaB activation, programmed cell death, and A20 gene expression.


RESULTS
Thirty-two different mutations were identified; 53% affect the zinc finger domain. Seventy-seven percent were associated with ectodermal dysplasia, 86% with serious pyogenic infection, 39% with mycobacterial infection, 19% with serious viral infection, and 23% with inflammatory diseases. Thirty-six percent of individuals died at a mean age of 6.4 years. CD40, IL-1, TNF-alpha, TLR, and T-cell receptor signals were impaired in 15 of 16 (94%), 6 of 7 (86%), 9 of 11 (82%), 9 of 14 (64%), and 7 of 18 (39%), respectively. Hypomorphism-reconstituted NEMO-deficient cells demonstrated partial restoration of NEMO functions. Although both L153R and C417R impaired TLR and TNF-alpha-induced NF-kappaB activation, L153R also increased TNF-alpha-induced programmed cell death with decreased A20 expression.


CONCLUSIONS
Distinct NEMO hypomorphs define specific disease and genetic characteristics. A reconstitution system can identify attributes of hypomorphisms independent of an individual's genetic background. Apoptosis susceptibility in L153R reconstituted cells defines a specific phenotype of this mutation that likely contributes to the excessive inflammation with which it is clinically associated.
Hanson
Eric P
EP
Division of Rheumatology, Joseph Stokes Jr Research Institute, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Monaco-Shawver
Linda
L
Solt
Laura A
LA
Madge
Lisa A
LA
Banerjee
Pinaki P
PP
May
Michael J
MJ
Orange
Jordan S
JS
D019943:Amino Acid Substitution; D017209:Apoptosis / Q000235:genetics; D019013:CD40 Antigens / Q000378:metabolism; D004268:DNA-Binding Proteins; D030541:Databases, Genetic; D005786:Gene Expression Regulation / Q000235:genetics; D005816:Genetic Complementation Test / Q000379:methods; D005838:Genotype; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics* / Q000378:metabolism*; D007153:Immunologic Deficiency Syndromes / Q000235:genetics* / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D020125:Mutation, Missense; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000096:biosynthesis; D010641:Phenotype; D017434:Protein Structure, Tertiary / Q000235:genetics; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D051198:Toll-Like Receptor 5 / Q000378:metabolism; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D019013:CD40 Antigens; D004268:DNA-Binding Proteins; C491731:IKBKG protein, human; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D011948:Receptors, Antigen, T-Cell; C495346:TLR5 protein, human; D051198:Toll-Like Receptor 5; D014409:Tumor Necrosis Factor-alpha; D051550:I-kappa B Kinase; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3