Functions of Ich-1(L). and Ich-1(S) in Apoptotic Signaling Pathway of jurkat T Cells

Lee, Sang Kyou; Shim, Jae Hyuck; Kim, Hyun Jung; Lim, Jung Hee

Abstract

Human caspase-2, Ich-1 (Ice and Ced-3 homolog), has two different forms of mRNA species derived from alternative splicing, which encodes Ich-1 and Ich-1s. Ich-1v which induces apoptosis is antagonist of Ich-1s which suppresses Rat-1 cell death by serum deprivation. To investigate functions of Ich-1 and Ich-1s in T celi apoptosis, the fusion DNA constructs were made with the ecto and transmembrane of CDB and Ich-lv or Ich-1s and CDS-Ich-1 or CD8-Ich-1s chimeric protein was transiently expressed on Jurkat T cells. Tyrosine phosphorylation of intracellular proteins was induced in these transfectans when activated shortly by anti-CDB Ab. CDB-Ich-li transfectant in serum-rich condition and CDB-Ich-ls transfectant in serum-deprived condition underwent apoptosis when treated with anti-CDS Ab or incubated with NIH3T3 cells expressing stably Fas-L on their surface. We also made six antisense DNA constructs which could specifically inhibit the expression of Ich-1v, Ich- 1s, and then they were transiently transfected into Jurkat T cell. The overexpression of both of the antisese- Ich-1 against N-terminal 42 bp and against C-terminal 366 bp inhibited apoptosis through Fas signalling. But, when three different forms of antisense-Ich-1s were overexpressed in their transfectants, antisense-DNA against N-terminal 197 bp increased knd the one against C-terminal 66 bp inhibited apoptosis, instead the full size of antisense-DNA did not give any effects on apoptosis through Fas pathway.