Drosophila JAK/STAT Signalling pathway

Summary:

In Drosophila, three secreted ligands (OS, UPD2 and UPD3) have been identified for the JAK/STAT pathway. Their binding to the receptor dome induces its homo-dimerization, enabling hop to phosphorylate specific tyrosine residues of the receptor. Consequently, STAT92E is also phosphorylated by HOP, leading to his homo-dimerization and nuclear translocation. In the nucleus, STAT92E binds to target DNA sequences and acts as an activator of transcription of several target genes ([1]). During Drosophila development, the JAK/STAT pathway is involved in embryonic segmentation, eye development, cell growth, haematopoiesis, and sex determination ([2]; [3]). JAK/STAT signalling also plays important roles during spermatogenesis ([4]) and oogenesis ([5]; [6]; [3]). To study the dynamic of the pathway, we define a set of initial states representative of in vivo situations during JAK/STAT signalling. More precisely, we define a three initial states corresponding to pathway signalling (binding of OS or UPD2 or UPD3) and two initial states corresponding to pathway signalling in the presence of an inhibitor (SOCS44A or BRWD3) and one initial state corresponding to non signalling conditions (no binding of ligands).