Control mechanism of JAK/STAT signal transduction pathway.

Suppressor of cytokine signaling-1 (SOCS1) was identified as the negative regulator of Janus kinase (JAK) and signal transducer and activator of transcription (STAT) signal transduction pathway. However, the kinetics and control mechanism of the pathway have not yet been fully understood. We have developed the computer simulation of the JAK/STAT pathway. Without nuclear phosphatase, SOCS1's binding to JAK did not cause the decrease in nuclear phosphorylated STAT1. However, without SH2 domain-containing tyrosine phosphatase 2 (SHP-2) or cytoplasmic phosphatase, it did. So nuclear phosphatase is considered to be the most important in this system. By changing parameters of the model, dynamical characteristics and control mechanism were investigated.