THE STAT5 SIGNALING IN THE EXPRESSION OF ALPHA-SUBUNIT OF INTERLEUKIN-2 RECEPTOR IN HUMAN BLOOD LYMPHOPCYTES
E.V. Mityushova, A.N. Shatrova, V.V. Zenin, N.A. Aksenov, I.I. Marakhova
Institute of Cytology RAS, St.-Petersburg;
e-mail: elena-mityushova@yandex.ru
The comparative study of the STAT3 and STAT5 activity (as assessed by tyrosine phosphorylation level) and the expression of a α-subunit of interleukin-2 receptor
(as examined by cytophotometric evaluation of the number of CD25+ cells) during the phytohemagglutinin (PHA)-induced proliferation of human blood lymphocytes (HBL)
have been made. It is revealed that the level of STAT3 phosphorylation is high in both resting and competent HBL and remains unchanged in the presence of PHA or interleukin-2
(IL-2). In contrast to STAT3, in both resting and competent HBL the phosphorylation of STAT5 was not seen. In the presence of PHA we observed the phosphorylation of STAT5
not earlier than at 5 hours and the maximum phosphorylation was detected following 24 h. In the competent HBL exogenous IL-2 induced a high phosphorylation of STAT5 as early
as at 30 min and the STAT5 phosphorylation kept at high level next 24-48 h. A correlation between alterations in tyrosine phosphorylation level of STAT5 and the expression of
CD25 was established. WHI-P131, an inhibitor of JAK3 kinase, prevents STAT5 activation, cell surface expression of CD25 and lymphocyte proliferation. It is concluded that
JAK3/STAT5 signaling via IL-2 receptor in necessary to support the long-term expression of high-affinity, αβγc - receptor
of IL-2 and optimal proliferation of HBL.
Key words: human lymphocytes, STAT3, STAT5, interleukin-2 receptor, α-subunit of the interleukin-2 receptor, CD25, JAK
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