Sequestosome 1 mutations in Paget's disease of bone in Australia: prevalence, genotype/phenotype correlation, and a novel non-UBA domain mutation (P364S) associated with increased NF-kappaB signaling without loss of ubiquitin binding.
Previously reported Sequestosome 1(SQSTM1)/p62 gene mutations associated with Paget's disease of bone (PDB) cluster in, or cause deletion of, the ubiquitin-associated (UBA) domain. The aims of this study were to examine the prevalence of SQSTM1 mutations in Australian patients, genotype/phenotype correlations and the functional consequences of a novel point mutation (P364S) located upstream of the UBA. Mutation screening of the SQSTM1 gene was conducted on 49 kindreds with PDB. In addition, 194 subjects with apparently sporadic PDB were screened for the common P392L mutation by restriction enzyme digestion. HEK293 cells stably expressing RANK were co-transfected with expression plasmids for SQSTM1 (wildtype or mutant) or empty vector and a NF-kappaB luciferase reporter gene. GST-SQSTM1 (wildtype and mutant) proteins were used in pull-down assays to compare monoubiquitin-binding ability. We identified SQSTM1 mutations in 12 of 49 families screened (24.5%), comprising 9 families with the P392L mutation and 1 family each with the following mutations: K378X, 390X, and a novel P364S mutation in exon 7, upstream of the UBA. The P392L mutation was found in 9 of 194 (4.6%) patients with sporadic disease. Subjects with SQSTM1 mutations had more extensive disease, but not earlier onset, compared with subjects without mutations. In functional studies, the P364S mutation increased NF-kappaB activation compared with wildtype SQSTM1 but did not reduce ubiquitin binding. This suggests that increased NF-kappaB signaling, but not the impairment of ubiquitin binding, may be essential in the pathogenesis of PDB associated with SQSTM1 mutations.
Rea
Sarah L
SL
Laboratory for Molecular Endocrinology, Western Australian Institute for Medical Research and UWA Centre for Medical Research, University of Western Australia, Nedlands, Australia. smorgan@cyllene.uwa.edu.au
Walsh
John P
JP
Ward
Lynley
L
Magno
Aaron L
AL
Ward
Bryan K
BK
Shaw
Barry
B
Layfield
Robert
R
Kent
G Neil
GN
Xu
Jiake
J
Ratajczak
Thomas
T
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism*; D000328:Adult; D000368:Aged; D019943:Amino Acid Substitution; D001315:Australia / Q000453:epidemiology; D002460:Cell Line; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010001:Osteitis Deformans / Q000453:epidemiology / Q000235:genetics* / Q000378:metabolism*; D010375:Pedigree; D010641:Phenotype; D015995:Prevalence; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D000071456:Sequestosome-1 Protein; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D016328:NF-kappa B; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D025801:Ubiquitin