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Increasing evidence demonstrates that melatonin has an anti-inflammatory effect. Nevertheless, the molecular mechanisms remain obscure. In this study, we investigated the effect of melatonin on toll-like receptor 4 (TLR4)-mediated molecule myeloid differentiation factor 88 (MyD88)-dependent and TRIF-dependent signaling pathways in lipopolysaccharide (LPS)-stimulated macrophages. RAW264.7 cells were incubated with LPS (2.0 μg/mL) in the absence or presence of melatonin (10, 100, 1000 μ m). As expected, melatonin inhibited TLR4-mediated tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10 in LPS-stimulated macrophages. In addition, melatonin significantly attenuated LPS-induced upregulation of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in macrophages. Further analysis showed that melatonin inhibited the expression of MyD88 in LPS-stimulated macrophages. Although it had no effect on TLR4-mediated phosphorylation of c-Jun N-terminal kinase (JNK), p38, and extracellular regulated protein kinase (ERK), melatonin significantly attenuated the activation of nuclear factor kappa B (NF-κB) in LPS-stimulated macrophages. In addition, melatonin inhibited TLR4-mediated Akt phosphorylation in LPS-stimulated macrophages. Moreover, melatonin significantly attenuated the elevation of interferon (IFN)-regulated factor-3 (IRF3), which was involved in TLR4-mediated TRIF-dependent signaling pathway, in LPS-stimulated macrophages. Correspondingly, melatonin significantly alleviated LPS-induced IFN-β in macrophages. In conclusion, melatonin modulates TLR4-mediated inflammatory genes through MyD88-dependent and TRIF-dependent signaling pathways. [ABSTRACT FROM AUTHOR]

Cellular signaling activities must be tightly regulated for proper cell fate control and tissue morphogenesis. Here we report that the Drosophila leucine-rich repeat transmembrane glycoprotein Gp150 is required for viability, fertility and development of the eye, wing and sensory organs. In the eye, Gp150 plays a critical role in regulating early ommatidial formation. Gp150 is highly expressed in cells of the morphogenetic furrow (MF) region, where it accumulates exclusively in intracellular vesicles in an endocytosis-independent manner. Loss of gp150 function causes defects in the refinement of photoreceptor R8 cells and recruitment of other cells, which leads to the formation of aberrant ommatidia. Genetic analyses suggest that Gp150 functions to modulate Notch signaling. Consistent with this notion, Gp150 is co-localized with Delta in intracellular vesicles in cells within the MF region and loss of gp150 function causes accumulation of intracellular Delta protein. Therefore, Gp150 might function in intracellular vesicles to modulate Delta±Notch signaling for cell fate control and tissue morphogenesis. [ABSTRACT FROM AUTHOR]

Drosophila INAD, which contains five tandem protein interaction PDZ domains, plays an important role in the G protein-coupled visual signal transduction. Mutations in InaD alleles display mislocalization of signaling molecules of phototransduction which include the essential effector, phospholipase C-β (PLC-β), which is also known as NORPA. The molecular and biochemical details of this functional link are unknown. We report that INAD directly binds to NORPA via two terminally positioned PDZ1 and PDZ5 domains. PDZ1 binds to the C-terminus of NORPA, while PDZ5 binds to an internal region overlapping with the G box-homology region (a putative G protein-interacting site). The NORPA proteins lacking binding sites, which display normal basal PLC activity, can no longer associate with INAD in vivo. These truncations cause significant reduction of NORPA protein expression in rhabdomeres and severe defects in phototransduction. Thus, the two terminal PDZ domains of INAD, through intermolecular and/or intramolecular interactions, are brought into proximity in vivo. Such domain organization allows for the multivalent INAD­NORPA interactions which are essential for G protein-coupled phototransduction. [ABSTRACT FROM AUTHOR]