title: Different apoptotic responses of RA synoviocytes depending on different genotypes of the mdm2 SNP                      T309G.
abstract: Mdm2 is an ubiquitin ligase, which binds p53 and blocks its function as a transcription factor in the pathway of apoptosis. Recently we have showed that the SNP mdm2 T309G has a protective effect of the minor allele in rheumatoid arthritis (RA). However, a functional impact on apoptosis by the different genotypes of the mdm2 SNP has not been investigated. Genomic DNA was obtained from 49 cell lines of synoviocytes derived from 49 patients with RA, and the mdm2 SNP309 was genotyped by polymerase chain reaction and restriction enzyme analysis. Seven cell lines were identified as homozygous for TT (major allele of mdm2 SNP309), and four as homozygous for GG (minor allele). All 11 cell lines were stimulated with 5 ng/ml of TNF alpha and 2.5 ng/ml of Il-1beta. After staining with propidium iodide (25 µg/ml) DNA fluorescence was measured with FACS; the rate of apoptosis was defined as the percentage of cells with a sub-2n DNA content (= less than haploid DNA-content). The cell-lines genotyped with mdm2 SNP 309TT showed a significantly different apoptosis rate in percent compared with GG for both conditions with stimulation (19.4 ± 3.6 vs. 26.9 ± 1.8; P = 0.02) and without stimulation by TNF alpha and Il-1beta (27.4 ± 8.8 vs. 43.9 ± 2.4; P = 0.0002). In the cell culture in vitro model RA synoviocytes homozygous for mdm2 SNP 309GG had a higher apoptotic activity compared to TT, possibly identifying a protective effect of the minor allele.
authors.affiliation: Internal Medicine I, University of Saarland Medical School, Homburg/Saar, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Heyne
authors.forename: Judith
authors.initials: J
authors.lastname: Huwer
authors.forename: Vincent
authors.initials: V
authors.lastname: Zimmer
authors.forename: Michael
authors.initials: M
authors.lastname: Pfreundschuh
authors.forename: Jasmin Teresa
authors.initials: JT
authors.lastname: Ney
authors.forename: Gunter
authors.initials: G
authors.lastname: Assmann
mesh_terms: D000368:Aged; D017209:Apoptosis; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics* / Q000378:metabolism; D013582:Synovial Fluid / Q000166:cytology*
chemical_list: D051736:Proto-Oncogene Proteins c-mdm2