Expression and function of AIM, an activation inducer molecule of human lymphocytes, is dependent on the activation of protein kinase C

Abstract

AIM is an activation inducer molecule selectively expressed by activated lymphocytes through which agonistic proliferative signals can be triggered. The relationship between the expression of AIM with the activation of protein kinase C (PKC) has been studied. Different activators of PKC such as the active phorbol esters, phorbol myristate acetate and phorbol dibutyrate, or the phorbol-related ester mezerein were able to induce AIM expression on peripheral blood lymphocytes as assessed by immunofluorescence flow cytometry. Moreover, the expression of this activation antigen was also induced by treatment of peripheral blood lymphocytes either with dioctanoyl-rac-glycerol, a synthetic analogue of diacylglycerol, the physiological mediator of PKC activation. Further indirect evidence that AIM expression was dependent on the activation of PKC was obtained by blockade of the induction of its expression in cells treated with H7, an inhibitor of PKC. The AIM expression can be detected as early as 3 h after addition of phorbol esters and it requires active RNA and protein synthesis. The activation of PKC appears to be also required in the proliferative response induced by anti-AIM monoclonal antibody (mAb) in conjunction with phorbol esters. Agents such as phorbol myristate acetate, phorbol dibutyrate or mezerein but not the inactive phorbol ester methyl-phorbol myristate acetate induced a high proliferation of peripheral blood lymphocytes in the presence of anti-AIM mAb. In addition, we have demonstrated that the anti-AIM mAb is not sufficient by itself to induce cellular proliferation once the AIM antigen is expressed at the cell surface, requiring the simultaneous stimulation of the PKC to trigger high proliferative responses. Furthermore, the anti-AIM mAb did not appear to exert its effect on proliferation by rapidly increasing the intracytoplasmic Ca2+ levels. Taken together all these results indicate that the expression and function of AIM antigen is dependent on the activation of PKC.

Dasatinib, a small-molecule protein tyrosine kinase inhibitor, inhibits T-cell activation and proliferation

“…PMA is capable of inducing CD69 expression via protein kinase C, effectively bypassing the TCR and thus Lck dependency. 23 PBMCs were placed into overnight culture with OKT3 in the presence or absence of dasatinib, and CD69 expression was analyzed by flow cytometry. As shown, CD69 is readily induced on OKT3-stimulated T cells but completely inhibited when dasatinib was added ( Figure 3A top panels).…”

Involvement of p21ras activation in T cell CD69 expression

“…The analysis of the requirements for CD69 expression in lymphoid cells has suggested that sustained PKC activation could be responsible for TcRICD3-mediated CD69 induction [3,14,15]. However, in NK cells IL-2 is likely to trigger [I 123811 Supported by grants from the CNR Progetto Bilaterale and the Associazione Italiana Ricerca sul Cancro.…”

Analysis of different protein kinase C-dependent events in T cells from allogeneic bone marrow transplantation recipients

“…We have also provided data indicating that regardless of the proliferative ability, the large miijority of BMT recipient Tcells were capable of dc novo expressing the C"D69 surface antigen, an event which takes place rapidly in T cells upon nctivation and is PKC-dcpcndent. thus reflecting the capacity of the cn/yme to induce gene expression [12]. However.…”

“…Firsl. we have assessed the capacity ofT cells lYom IIMT recipients to express the CD69 molecule, an curly aclivalion antigen dc novo synthesized after stimulation of PKC [12]. in addition, since anti-CD6y MoAbs can trigger agonistic signals complementary to PKC activation which activate lymphocyte proliferation [13].…”