Signaling pathways of leukocyte membrane receptors, their regulation and deficiencies

Because of the profound effects of signal transduction on cell behaviour, the activity of signalling pathways must be carefully regulated. Otherwise, dysregulation of signalling might harm the organism by not responding to danger or by an excessively strong reaction. Therefore, various regulatory mechanisms became essential parts of signal transduction pathways. They affect these pathways at all levels, including ligands, receptors, signalling enzymes, adaptor proteins and other signalling mediators, as well as transcription factors further downstream. In this thesis, I present the results of the research on the role of transmembrane and membrane associated adaptor proteins LST1, SCIMP, PSTPIP2 and WBP1L in the regulation of leukocyte signalling and homeostasis. Transmembrane adaptor protein LST1 is a short protein expressed in the cells of the myeloid lineage. Observation of LST1-/- mice revealed that these animals are overall healthy without visible phenotype, with the exception of mild reductions in myeloid, NK and NKT cell populations at the steady state. On the other hand, LST1 deficiency had significant protective effect during acute colitis induced by dextran sodium sulphate, suggesting the role of LST1 in the regulation of gut inflammation. Studies on PSTPIP2 and SCIMP presented in this..