Abstract
Interleukin- (IL-) 2 is the major growth factor for T-cell activation and proliferation. IL-2 has multiple functions in the regulation of immunological processes. Although most studies focus on T-cell immunomodulation, T-cell activation by IL-2 is the foundation of priming the feedback loop. Here, we investigated the effect of MAPK/ERK and PI3K/Akt signaling pathways on IL-2-induced cell activation and the regulatory mechanisms of upstream ubiquitin ligase Cbl-b and c-Cbl. Morphological analysis of Jurkat T cells was performed by cytospin preparations with Wright-Giemsa stain. CD25 expression on Jurkat T cells was determined by flow cytometry. Changes in cell activation proteins such as p-ERK, ERK, p-Akt, Akt, and ubiquitin ligase Casitas B-cell Lymphoma (Cbl) proteins were analyzed by western blot. Following IL-2-induced activation of Jurkat T cells, p-ERK expression was upregulated, while there was no change in p-Akt, ERK, or Akt expression. Thus, the MAPK/ERK signaling pathway, but not PI3K/Akt, was involved in IL-2-induced T-cell activation. Either using PD98059 (a specific inhibitor for p-ERK) or depletion of ERK with small interfering RNA (siRNA) reduced the expression of CD25. This study also showed that ubiquitin ligase proteins Cbl-b and c-Cbl might be involved in IL-2-induced Jurkat T-cell activation by negatively regulating the MAPK/ERK signaling pathway.
Highlights
In the late 1970s, Smith et al first described interleukin(IL-) 2 as a T-cell growth factor produced by T lymphocytes [1]
IL-2 receptor (IL-2R) signaling is initiated by phosphorylation of JAK3 and JAK1, which are constitutively associated with the gc and IL-2R beta chains, respectively
To verify whether IL-2 induces T-cell activation, Jurkat T cells were exposed to different concentrations of IL-2 (50 U/mL and 250 U/mL) for 48 h or 72 h
Summary
In the late 1970s, Smith et al first described interleukin(IL-) 2 as a T-cell growth factor produced by T lymphocytes [1]. IL-2R signaling is initiated by phosphorylation of JAK3 and JAK1, which are constitutively associated with the gc and IL-2R beta chains, respectively Activation of these kinases leads to the activation of PI3K/Akt, MAPK/ERK, and the STAT family of transcription factors [3]. Several studies have shown that T cells expressing active Akt are resistant to activation-induced apoptosis in vitro and in vivo [12, 13] It remains unknown whether Cblb and c-Cbl are involved in the activation of T cells, through downregulation of the PI3K/Akt signaling pathways. To investigate the mechanisms of IL-2-induced T-cell activation, we used a human leukemia cell line, Jurkat T cells, as a model to study the expression of a cell surface activation marker CD25, the effect of MAPK/ERK and PI3K/Akt signaling pathways in the activation process, and the regulatory mechanisms of upstream ubiquitin ligase Cblb and c-Cbl
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
