Topic
Signal transduction
About: Signal transduction is a research topic. Over the lifetime, 122628 publications have been published within this topic receiving 8209258 citations. The topic is also known as: GO:0007165.
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TL;DR: The findings suggest the need to reformulate concepts of cAMP-mediated signaling to include direct coupling to Ras superfamily signaling.
Abstract: cAMP (3',5' cyclic adenosine monophosphate) is a second messenger that in eukaryotic cells induces physiological responses ranging from growth, differentiation, and gene expression to secretion and neurotransmission. Most of these effects have been attributed to the binding of cAMP to cAMP-dependent protein kinase A (PKA). Here, a family of cAMP-binding proteins that are differentially distributed in the mammalian brain and body organs and that exhibit both cAMP-binding and guanine nucleotide exchange factor (GEF) domains is reported. These cAMP-regulated GEFs (cAMP-GEFs) bind cAMP and selectively activate the Ras superfamily guanine nucleotide binding protein Rap1A in a cAMP-dependent but PKA-independent manner. Our findings suggest the need to reformulate concepts of cAMP-mediated signaling to include direct coupling to Ras superfamily signaling.
1,347 citations
TL;DR: The data indicate a previously unknown mechanism of cellular activation involving the recruitment of TLR9 from the ER to sites of CpG DNA uptake, where signal transduction is initiated.
Abstract: Microbial DNA sequences containing unmethylated CpG dinucleotides activate Toll-like receptor 9 (TLR9). We have found that TLR9 is localized to the endoplasmic reticulum (ER) of dendritic cells (DCs) and macrophages. Because there is no precedent for immune receptor signaling in the ER, we investigated how TLR9 is activated. We show that CpG DNA binds directly to TLR9 in ligand-binding studies. CpG DNA moves into early endosomes and is subsequently transported to a tubular lysosomal compartment. Concurrent with the movement of CpG DNA in cells, TLR9 redistributes from the ER to CpG DNA–containing structures, which also accumulate MyD88. Our data indicate a previously unknown mechanism of cellular activation involving the recruitment of TLR9 from the ER to sites of CpG DNA uptake, where signal transduction is initiated.
1,343 citations
TL;DR: The molecules that initiate these signaling events, including the death domain- and TNF receptor associated factor (TRAF) domain-containing adapter proteins and the signaling enzymes associated with them, are largely unique to the TNF/nerve growth factor receptor family.
Abstract: ▪ Abstract Four members of the tumor necrosis factor (TNF) ligand family, TNF-α, LT-α, LT-β, and LIGHT, interact with four receptors of the TNF/nerve growth factor family, the p55 TNF receptor (CD120a), the p75 TNF receptor (CD120b), the lymphotoxin beta receptor (LTβR), and herpes virus entry mediator (HVEM) to control a wide range of innate and adaptive immune response functions. Of these, the most thoroughly studied are cell death induction and regulation of the inflammatory process. Fas/Apo1 (CD95), a receptor of the TNF receptor family activated by a distinct ligand, induces death in cells through mechanisms shared with CD120a. The last four years have seen a proliferation in knowledge of the proteins participating in the signaling by the TNF system and CD95. The downstream signaling molecules identified so far—caspases, phospholipases, the three known mitogen activated protein (MAP) kinase pathways, and the NF-κB activation cascade—mediate the effects of other inducers as well. However, the molecule...
1,342 citations
TL;DR: A new family of viral inhibitors (v-FLIPs) which interfere with apoptosis signalled through death receptors3 and which are present in several γ-herpesviruses (including Kaposi's-sarcoma-associated human herpesvirus-8), as well as in the tumorigenic human molluscipoxvirus4.
Abstract: Viruses have evolved many distinct strategies to avoid the host's apoptotic response Here we describe a new family of viral inhibitors (v-FLIPs) which interfere with apoptosis signalled through death receptors and which are present in several gamma-herpesviruses (including Kaposi's-sarcoma-associated human herpesvirus-8), as well as in the tumorigenic human molluscipoxvirus v-FLIPs contain two death-effector domains which interact with the adaptor protein FADD, and this inhibits the recruitment and activation of the protease FLICE by the CD95 death receptor Cells expressing v-FLIPs are protected against apoptosis induced by CD95 or by the related death receptors TRAMP and TRAIL-R The herpesvirus saimiri FLIP is detected late during the lytic viral replication cycle, at a time when host cells are partially protected from CD95-ligand-mediated apoptosis Protection of virus-infected cells against death-receptor-induced apoptosis may lead to higher virus production and contribute to the persistence and oncogenicity of several FLIP-encoding viruses
1,341 citations
TL;DR: PI( 3)K is a key player in many cellular responses, including the movement of organelle membranes, shape alteration through rearrangement of cytoskeletal actin, transformation and chemotaxis, but how PI(3)K mediates these responses is only now becoming clear.
Abstract: When a stimulatory agonist molecule binds at the exterior of the cell membrane, a second messenger transduces the signal to the interior of the cell. Second messengers can be derived from phospholipids in the membrane by the action of the enzymes phospholipase C or phosphoinositide-3-OH kinase (PI(3)K). PI(3)K is a key player in many cellular responses, including the movement of organelle membranes, shape alteration through rearrangement of cytoskeletal actin, transformation and chemotaxis. But how PI(3)K mediates these responses is only now becoming clear.
1,341 citations