TY - JOUR
T1 - Isolation and analysis of a T cell clone variant exhibiting constitutively phosphorylated Ser133 cAMP response element-binding protein
AU - Belkowski, Stanley M.
AU - Rubin, Charles S.
AU - Prystowsky, Michael B.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1998/7/15
Y1 - 1998/7/15
N2 - In driving T cell proliferation, IL-2 stimulates a new program of gene expression that includes proliferating cell nuclear antigen (PCNA), a requisite processivity factor for DNA polymerase δ. PCNA transcription is regulated in part through tandem CRE sequences in the promoter and CRE binding proteins; IL-2 stimulates CREB phosphorylation in the resting cloned T lymphocyte, L2. After culturing L2 cells for greater than 91 days, we consistently isolate a stable variant that exhibits constitutive CREB phosphorylation. L2 and L2 variant cells were tested for IL-2 responsiveness and rapamycin sensitivity with respect to specific kinase activity, PCNA expression and proliferation. In L2 cells, IL-2 stimulated and rapamycin inhibited the following: cAMP-independent CREB kinase activity, PCNA expression and proliferation. In L2 variant cells, CREB kinase activity was constitutively high; IL-2 stimulated and rapamycin blocked PCNA expression and proliferation. These results indicate that IL-2 induces a rapamycin- sensitive, cAMP-independent CREB kinase activity in L2 cells. However, phosphorylation of CREB alone is not sufficient to drive PCNA expression and L2 cell proliferation in the absence of IL-2.
AB - In driving T cell proliferation, IL-2 stimulates a new program of gene expression that includes proliferating cell nuclear antigen (PCNA), a requisite processivity factor for DNA polymerase δ. PCNA transcription is regulated in part through tandem CRE sequences in the promoter and CRE binding proteins; IL-2 stimulates CREB phosphorylation in the resting cloned T lymphocyte, L2. After culturing L2 cells for greater than 91 days, we consistently isolate a stable variant that exhibits constitutive CREB phosphorylation. L2 and L2 variant cells were tested for IL-2 responsiveness and rapamycin sensitivity with respect to specific kinase activity, PCNA expression and proliferation. In L2 cells, IL-2 stimulated and rapamycin inhibited the following: cAMP-independent CREB kinase activity, PCNA expression and proliferation. In L2 variant cells, CREB kinase activity was constitutively high; IL-2 stimulated and rapamycin blocked PCNA expression and proliferation. These results indicate that IL-2 induces a rapamycin- sensitive, cAMP-independent CREB kinase activity in L2 cells. However, phosphorylation of CREB alone is not sufficient to drive PCNA expression and L2 cell proliferation in the absence of IL-2.
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M3 - Article
C2 - 9670940
AN - SCOPUS:0032528430
SN - 0022-1767
VL - 161
SP - 659
EP - 665
JO - Journal of Immunology
JF - Journal of Immunology
IS - 2
ER -