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NGFI-A gene expression is necessary for T lymphocyte proliferation
A Perez-Castillo1, C Pipaón, I García
1Insituto Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Insights
The immediate early gene NGFI-A is crucial for lymphocyte proliferation. Its expression, triggered by IL-2 or ConA, is essential for T cell growth and mitogenic stimulation.
Area of Science:
- Molecular Biology
- Immunology
- Cell Biology
Background:
- NGFI-A is an immediate early gene encoding a zinc finger protein.
- It is rapidly activated following mitogenic stimulation in lymphocytes.
Purpose of the Study:
- To investigate the role of NGFI-A gene expression in lymphocyte proliferation.
- To understand the signaling pathways regulating NGFI-A induction.
Main Methods:
- Stimulation of lymphoblasts and T lymphocytes with Interleukin-2 (IL-2) and concanavalin A (ConA).
- Analysis of NGFI-A gene expression using signaling pathway activators (Ca2+, protein kinase C, 8-Bromo-cAMP).
- Inhibition of NGFI-A expression with antisense oligonucleotides.
Main Results:
- NGFI-A expression was rapidly induced by IL-2 in G1 lymphoblasts and during G0/G1 transition with ConA.
- Full NGFI-A induction required combined Ca2+ and protein kinase C activation in quiescent T lymphocytes.
- NGFI-A antisense oligonucleotide blocked ConA- and IL-2-induced lymphocyte proliferation.
Conclusions:
- NGFI-A plays a critical regulatory role in lymphocyte growth control.
- NGFI-A expression is essential for T cell proliferation following mitogenic stimulation.
Abstract:
NGFI-A is an immediate early gene, encoding a zinc finger protein, rapidly activated after mitogenic stimulation. NGFI-A gene expression was found to be rapidly and transiently induced after interleukin-2 (IL-2) stimulation of G1 lymphoblasts, as well as during the G0/G1 transition, when stimulated with concanavalin A (ConA). Activation of both Ca2+ and protein kinase C pathways, separately, in quiescent T lymphocytes produced a partial induction of this gene; however, both stimuli together are necessary to obtain a full response. ConA-induced activation of NGFI-A in quiescent cells was inhibited by immunosuppressors. 8-Bromo-cAMP was able to inhibit the expression of this gene in G1 lymphoblasts after IL-2 stimulation, but failed to interfere with the ConA-induced expression in quiescent T lymphocytes. Exposure of T cells to an NGFI-A antisense oligonucleotide blocked the ConA- and IL-2-induced proliferation of the cells, measured as thymidine incorporation and cell number. This inhibition provides direct evidence that the early gene NGFI-A plays a regulatory role in growth control processes of lymphocytes and that its expression is essential for cellular proliferation.