Modeling of tumor necrosis factor receptor superfamily 1A mutants associated with tumor necrosis factor receptor-associated periodic syndrome indicates misfolding consistent with abnormal function.
OBJECTIVE
To investigate the effect of mutations in the tumor necrosis factor receptor superfamily 1A (TNFRSF1A) gene on the conformation and behavior of the TNFRSF1A protein. Mutations in TNFRSF1A cause the autosomal-dominant, autoinflammatory TNFR-associated periodic syndrome (TRAPS).


METHODS
The expression of recombinant TNFRSF1A was compared in SK-HEp-1 endothelial cells and HEK 293 epithelial cells stably transfected with full-length R347A or Deltasig constructs of wild-type or TRAPS-associated mutant TNFRSF1A. TNF binding was assessed in HEK 293 cell lines expressing R347A wild-type or mutant TNFRSF1A. Homology modeling of the 3-dimensional structure of the ectodomains of wild-type and mutant TNFRSF1A was performed.


RESULTS
TRAPS-associated mutant and wild-type TNFRSF1A behaved differently and had different localization properties within the cell, as a direct result of mutations in the ectodomains of TNFRSF1A. From a structural perspective, mutants with a predicted structure similar to that of the wild-type protein (e.g., R92Q) behaved similarly to wild-type TNFRSF1A, whereas forms of TNFRSF1A with mutations predicted to drastically destabilize the protein structure (e.g., cysteine mutations) showed defects in cell surface expression and TNF binding.


CONCLUSIONS
The results obtained from the in vitro experiments, in combination with the modeled structures, indicate that the phenotype and clinical differences between different TRAPS-associated mutants of TNFRSF1A result from different conformations of the TNFRSF1A ectodomains.
Rebelo
Susana L
SL
University of Nottingham, Nottingham, UK. mrxslr@nottingham.ac.uk
Bainbridge
Susan E
SE
Amel-Kashipaz
Mohammad R
MR
Radford
Paul M
PM
Powell
Richard J
RJ
Todd
Ian
I
Tighe
Patrick J
PJ
D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D010505:Familial Mediterranean Fever / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008958:Models, Molecular; D020125:Mutation, Missense; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D047888:Receptors, Tumor Necrosis Factor, Type I; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha