title: Molecular alterations in the TCR signaling pathway in patients with aplastic anemia.
abstract: BACKGROUND
  A previous study has demonstrated a significantly increased CD3ζ gene expression level in aplastic anemia (AA). However, the mechanism underlying the upregulated CD3ζ mRNA expression level and that of T cell activation signaling molecules in AA patients remains unclear. Thus, we investigated the expression levels of the CD3ζ, CD28, CTLA-4, and Cbl-b genes, the SNP rs231775 in the CTLA-4 gene, and the distribution of the CD3ζ 3'-UTR splice variant in AA patients.
  
  
  METHODS
  CD3ζ 3'-UTR splice variants were identified in peripheral blood mononuclear cells (PBMCs) from 48 healthy individuals and 67 patients with AA [37 cases of severe aplastic anemia (SAA) and 30 cases of non-sever aplastic anemia (NSAA)] by RT-PCR. CD3ζ, CD28, CTLA-4, and Cbl-b gene expression was analyzed by real-time quantitative PCR. The SNP rs231775 in CTLA-4 gene was analyzed by PCR-RFLP.
  
  
  RESULTS
  CD3ζ and CD28 expression was significantly higher, while CTLA-4 and Cbl-b expression was significantly lower in AA patients compared with healthy individuals. Significantly higher CD3ζ expression was found in the NSAA subgroup compared with the SAA subgroup. 64 % of the AA samples had the same genotype (WT(+)AS(+)CD3ζ 3'-UTR); 22 % of the AA patients had a WT(+)AS(-)CD3ζ 3'-UTR genotype, and 14 % of the AA patients had a WT(-)AS(+)CD3ζ 3'-UTR genotype. The CD3ζ expression level of WT(-)AS(+) subgroup was the highest in the SAA patients. A significantly higher frequency of the GG genotype (mutant type, homozygous) of SNP rs231775 in CTLA-4 gene was found in the AA patients. Positive correlation between the CTLA-4 and Cbl-b gene expression levels was found in healthy individuals with the AA and AG genotypes, but not in the AA patients.
  
  
  CONCLUSIONS
  This is the first study analyzing the expression characteristics of the CD28, CTLA-4, and Cbl-b genes in AA. Our results suggest that aberrant T cell activation may be related to the first and second signals of T cell activation in AA. The GG genotype of SNP rs231775 in CTLA-4 gene might be associated with AA risk in the Chinese population. The characteristics of CD3ζ 3'-UTR alternative splicing may be an index for evaluating the T cell activation status in AA patients, particularly in SAA patients.
authors.affiliation: Institute of Hematology, Medical College, Jinan University, Guangzhou, China. libo517@jnu.edu.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Institute of Hematology, Medical College, Jinan University, Guangzhou, China.
authors.forename: Lixing
authors.initials: L
authors.lastname: Guo
authors.affiliation: Department of Hematology, Guangzhou First Municipal People's Hospital Affiliated to Guangzhou Medical College, Guangzhou, China.
authors.forename: Yuping
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China.
authors.forename: Yankai
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: Institute of Hematology, Medical College, Jinan University, Guangzhou, China.|Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China.
authors.forename: Mingjuan
authors.initials: M
authors.lastname: Wu
authors.affiliation: Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Institute of Hematology, Medical College, Jinan University, Guangzhou, China.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Chen
authors.affiliation: Institute of Hematology, Medical College, Jinan University, Guangzhou, China.
authors.forename: Lijian
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Hematology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Lu
authors.affiliation: Institute of Hematology, Medical College, Jinan University, Guangzhou, China. yangqiuli@hotmail.com.|Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China. yangqiuli@hotmail.com.|Department of Hematology, First Affiliated Hospital, Jinan University, Guangzhou, China. yangqiuli@hotmail.com.
authors.forename: Yangqiu
authors.initials: Y
authors.lastname: Li
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017398:Alternative Splicing; D000741:Anemia, Aplastic / Q000235:genetics* / Q000473:pathology; D018106:CD28 Antigens / Q000235:genetics; D017252:CD3 Complex / Q000235:genetics; D060908:CTLA-4 Antigen / Q000235:genetics; D002648:Child; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D050721:Proto-Oncogene Proteins c-cbl / Q000235:genetics; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*; D055815:Young Adult
chemical_list: D020413:3' Untranslated Regions; D048868:Adaptor Proteins, Signal Transducing; D018106:CD28 Antigens; D017252:CD3 Complex; C121704:CD3 antigen, zeta chain; D060908:CTLA-4 Antigen; D011948:Receptors, Antigen, T-Cell; C492211:CBLB protein, human; D050721:Proto-Oncogene Proteins c-cbl
keywords: AA; CD28; CD3ζ; CD3ζ 3′-UTR splice variant; CTLA-4; Cbl-b; Gene expression level; SNP