MOLECULAR-CLONING OF CDNAS FOR THE RAT INTERLEUKIN-2 RECEPTOR ALPHA-CHAIN AND BETA-CHAIN GENES - DIFFERENTIALLY REGULATED GENE ACTIVITY IN RESPONSE TO MITOGENIC STIMULATION

We have isolated, by transient expression and screening using an oligonucleotide probe, cDNA clones encoding the rat interleukin 2 receptor (IL 2R) alpha and beta-chains, respectively. Both chains are approximately 60% identical at the amino acid level to their human counterparts. In common with the human and mouse IL 2R beta-chains, the rat beta-chain is a member of the cytokine receptor family. The rat IL 2R beta-chain contains no conventional signal transduction machinery and, like the mouse IL 2R beta-chain, has a significant number of deletions in its cytoplasmic tail in comparison to the human protein. Northern analysis indicates that the rat beta-chain message is constitutively transcribed in normal resting lymphocytes, whereas the alpha-chain message is absent. Transcription of both chains of the receptor is up-regulated by cellular activation. However, kinetic studies have shown that whereas alpha-chain message is rapidly induced, and can be detected 5 h after the addition of phytohemagglutinin, levels of beta-chain mRNA increase at a much later time point and are not seen to rise until approximately 24 h after the addition of mitogen. These data suggest that the expression of high-affinity IL 2R is controlled by factors which influence transcription of both the alpha and the beta-chain genes.