Impaired induction of c-fos/c-jun genes and of transcriptional regulatory proteins binding distinct c-fos/c-jun promoter elements in activated human T cells during aging.
The activation of transcriptional factor c-Fos/c-Jun AP-1 is essential for normal T cell responsiveness and is often impaired in T cells during aging. In the present study, we investigated whether aberrancies in the regulation of c-fos/c-jun at the mRNA or protein level might underlie the age-associated impairments of AP-1 in human T cells. Whereas T cells from young subjects stimulated with cross-linked anti-CD3epsilon mAb OKT3 plus PMA or with the lectin PHA plus PMA demonstrated considerable increases in c-Fos protein expression, the expression of c-Fos but not c-Jun was markedly reduced in stimulated T cells from certain elderly subjects. In addition, RNase protection assays revealed that anti-CD3/PMA-stimulated T cells from a substantial proportion of elderly subjects exhibited decreased levels of c-fos and/or c-jun mRNA compared to T cells from young subjects. Using electrophoretic mobility shift assays, the levels of nuclear regulatory proteins recognizing the AP-1 consensus TRE motif, the proximal c-jun TRE-like promoter element, and the c-fos serum response element (SRE) were determined in resting and stimulated T cells. Although the stimulation of T cells from young subjects resulted in coordinated increases of nuclear protein complexes binding the AP-1 TRE, c-jun TRE, and c-fos SRE DNA sequence motifs, age-related reductions in the activation of AP-1 were accompanied by decreased levels of c-jun TRE and c-fos SRE binding complexes. Furthermore, the nuclear protein complexes binding the SRE motif induced in activated T cells of young and elderly subjects contained serum response factor and Elk-1 pointing toward age-related defects in the activation of transcriptional regulatory proteins distinct from c-jun/AP-1. These results suggest that underlying aberrancies in the induction of c-fos/c-jun as well as their nuclear regulatory proteins may contribute to the age-related impairments of AP-1 activation in human T cells.
Whisler
R L
RL
Department of Medical Biochemistry, The William H. Davis Medical Research Center, The Ohio State University, Columbus 43210-1228, USA.
Chen
M
M
Beiqing
L
L
Carle
K W
KW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D001483:Base Sequence; D015342:DNA Probes / Q000235:genetics; D005786:Gene Expression Regulation; D016762:Genes, fos; D016758:Genes, jun; D006801:Humans; D066298:In Vitro Techniques; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism
D015342:DNA Probes; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1