UP-REGULATED EXPRESSION OF MICA ON ACTIVATED T LYMPHOCYTES INVOLVES LCK AND FYN KINASES AND SIGNALING THROUGH MEK1/ERK, P38 MAP KINASE AND CALCINEURIN

LUCIANA MOLINERO; MERCEDES FUERTES; LEONARDO FAINBOIM; GABRIEL RABINOVICH; NORBERTO ZWIRNER

JOURNAL OF LEUKOCYTE BIOLOGY

Society of Leukocyte Biology-FASEB

Lugar: Bethesda, MD; Año: 2003 vol. 73 p. 815 - 822

0741-5400

Major histocompatibility complex class I-related chain (MICA) is a cell stress-regulated molecule recognized by cytotoxic cells expressing the NKG2D molecule. MICA can be induced on T cells after CD3 or CD28 engagement. Here, we investigated the intracellular pathways leading to activation-induced expression of MICA. The Src kinase inhibitor PP1 inhibited up-regulated expression of MICA on anti-CD3-stimulated T cells. Downstream signaling routes involved mitogen-activated protein kinase (MAPK) kinase (MEK)1/extracellular signal-regulated kinase (ERK), p38 MAPK, and calcineurin, as MICA expression was prevented by U0126, SB202190, cyclosporin A, and FK506. Also, Lck and Fyn as well as MEK1/ERK and p38 MAPK were found to regulate MICA expression in anti-CD28/phorbol 12-myristate 13-acetate-stimulated T cells. Expression of MICA on activated T cells involved interleukin-2-dependent signaling routes triggered by Janus tyrosine kinases/signal transducer and activators of transcription and p70(S)(6) kinase, as it could be inhibited by AG490 and rapamycin. This is the first demonstration of the intracellular pathways involved in activation-induced expression of MICA, which may reveal potential targets for immune intervention to modulate MICA expression in pathological disorders.