We propose a series of studies of T lymphocyte activation in old and young mice aimed at identifying in biochemical terms of defect(s) that prevent many T cells from old mice from responding to mitogens. We have previously shown age-related derangements in the generation of cytoplasmic calcium signals in T cells from old donors, and now propose to test two explanatory hypotheses: (a) that aged T cells have over-active calcium extrusion systems; and (b) that the low resting membrane potential of T cells from old mice interferes with calcium signal degeneration. Our studies of early signal transduction have hinted that pathways dependent on protein kinase C may be less impaired by aging than other kinase- dependent paths; we now propose more direct and systematic tests of protein kinase function and substrate specificity in T cells from old mice. We have previously documented age-related defects in Con A-induced expression of c-myc mRNA. We now propose to test for age-related changes in expression of selected cell cycle related genes (c-fos, c-jun IL-2, and IL-2R) in responses to mitogenic stimuli (Con A, anti-CD3). Nonmitogenic activators (PMA, ionomycin) will be used in studies of gene expression and protein kinase function to identify pathways to particularly susceptible to age-related dysfunction. Antibodies to c-myc and c-fos proteins will be used to look for altered gene expression at the single cell level and in T cell subsets thought to be particularly susceptible to senescent change. Finally we propose to look for evidence of age-related defects in splicing of primary RNA transcripts, defects that we have previously suggested may be responsible for age-related loss of myc mRNA accumulation. We hope to identify specific age-related defects in calcium signals, protein kinase function, and gene expression that might contribute to poor T lymphocyte function in old mice.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37AG009801-06
Application #
2051093
Study Section
Special Emphasis Panel (NSS)
Project Start
1990-08-01
Project End
1998-07-31
Budget Start
1995-08-01
Budget End
1996-07-31
Support Year
6
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Pathology
Type
Schools of Medicine
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Miller, R A (2000) Effect of aging on T lymphocyte activation. Vaccine 18:1654-60
Tamir, A; Eisenbraun, M D; Garcia, G G et al. (2000) Age-dependent alterations in the assembly of signal transduction complexes at the site of T cell/APC interaction. J Immunol 165:1243-51
Eisenbraun, M D; Tamir, A; Miller, R A (2000) Altered composition of the immunological synapse in an anergic, age-dependent memory T cell subset. J Immunol 164:6105-12
Kirk, C J; Freilich, A M; Miller, R A (1999) Age-related decline in activation of JNK by TCR- and CD28-mediated signals in murine T-lymphocytes. Cell Immunol 197:75-82
Witkowski, J M; Miller, R A (1999) Calcium signal abnormalities in murine T lymphocytes that express the multidrug transporter P-glycoprotein. Mech Ageing Dev 107:165-80
Yang, D; Miller, R A (1999) Cluster formation by protein kinase Ctheta during murine T cell activation: effect of age. Cell Immunol 195:28-36
Tamir, A; Miller, R A (1999) Aging impairs induction of cyclin-dependent kinases and down-regulation of p27 in mouse CD4(+) cells. Cell Immunol 198:11-20
Telford, W G; Miller, R A (1999) Aging increases CD8 T cell apoptosis induced by hyperstimulation but decreases apoptosis induced by agonist withdrawal in mice. Cell Immunol 191:131-8
Kirk, C J; Miller, R A (1999) Age-sensitive and -insensitive pathways leading to JNK activation in mouse CD4(+) T-cells. Cell Immunol 197:83-90
Kirk, C J; Miller, R A (1998) Analysis of Raf-1 activation in response to TCR activation and costimulation in murine T-lymphocytes: effect of age. Cell Immunol 190:33-42

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