Activation of p21ras/MAPK signal transduction molecules decreases with age in mitogen-stimulated T cells from rats.
Signal transduction is ubiquitously involved in the initiation of physiological signals that lead to growth and proliferation of cells. The signaling cascade mediated by the mitogen-activated protein kinase (MAPK) is considered essential for T cell growth and function. Therefore, it was of interest to determine the influence of age on the induction of MAPK in mitogen-activated T cells. T cells from young (4-6 months) and old (24-26 months) rats responded to concanavalin A (Con A) stimulation by increasing MAPK, c-jun amino terminal kinase (JNK), and p21ras activities. The time course of induction of MAPK/JNK and p21ras activities was similar in T cells isolated from young and old rats. The induction of JNK activity did not change significantly with age; however, the induction of MAPK and p21ras activities was significantly less (50 to 65%) in T cells from old rats than in T cells from young rats. Although the relative protein levels of p42 and p44 MAPK did not change with age, the proportion of the phosphorylated p44 MAPK decreased with age. In addition, it was found that the in vitro kinase activities of the T cell receptor-associated protein tyrosine kinase Lck (p56Lck) and ZAP-70 but not Fyn (p59Fyn) were lower in T cells from old rats than in T cells from young rats. The decline in activities of these signaling molecules with age was not associated with changes in their corresponding protein levels. Thus, our results demonstrate that aging alters the activation of the signal transduction cascade that leads to T cell activation.
Pahlavani
M A
MA
Geriatric Research, Education, and Clinical Center, Audie L. Murphy Veterans Hospital, San Antonio, Texas 78284, USA.
Harris
M D
MD
Richardson
A
A
D000375:Aging / Q000276:immunology*; D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000276:immunology / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology; D004789:Enzyme Activation / Q000276:immunology; D004790:Enzyme Induction / Q000276:immunology; D048031:JNK Mitogen-Activated Protein Kinases; D008213:Lymphocyte Activation / Q000502:physiology*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D008297:Male; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D051746:ZAP-70 Protein-Tyrosine Kinase
D011518:Proto-Oncogene Proteins; D003208:Concanavalin A; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C494961:Fyn protein, rat; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051076:Proto-Oncogene Proteins c-fyn; D051746:ZAP-70 Protein-Tyrosine Kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras)