TY - JOUR TI - LynA regulates an inflammation-sensitive signaling checkpoint in macrophages AU - Freedman, Tanya S AU - Tan, Ying X AU - Skrzypczynska, Katarzyna M AU - Manz, Boryana N AU - Sjaastad, Frances V AU - Goodridge, Helen S AU - Lowell, Clifford A AU - Weiss, Arthur A2 - Davis, Roger VL - 4 PY - 2015 DA - 2015/10/30 SP - e09183 C1 - eLife 2015;4:e09183 DO - 10.7554/eLife.09183 UR - https://doi.org/10.7554/eLife.09183 AB - Clustering of receptors associated with immunoreceptor tyrosine-based activation motifs (ITAMs) initiates the macrophage antimicrobial response. ITAM receptors engage Src-family tyrosine kinases (SFKs) to initiate phagocytosis and macrophage activation. Macrophages also encounter nonpathogenic molecules that cluster receptors weakly and must tune their sensitivity to avoid inappropriate responses. To investigate this response threshold, we compared signaling in the presence and absence of receptor clustering using a small-molecule inhibitor of Csk, which increased SFK activation and produced robust membrane-proximal signaling. Surprisingly, receptor-independent SFK activation led to a downstream signaling blockade associated with rapid degradation of the SFK LynA. Inflammatory priming of macrophages upregulated LynA and promoted receptor-independent signaling. In contrast, clustering the hemi-ITAM receptor Dectin-1 induced signaling that did not require LynA or inflammatory priming. Together, the basal-state signaling checkpoint regulated by LynA expression and degradation and the signaling reorganization initiated by receptor clustering allow cells to discriminate optimally between pathogens and nonpathogens. KW - macrophage KW - cell signaling KW - Src-family kinases KW - innate immunity KW - ITAMs KW - receptor JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -