Endocannabinoids are released from postsynaptic neurons and cause retrograde suppression of synaptic transmission. Anandamide and 2-arachidonoylglycerol (2-AG) are regarded as two major endocannabinoids. To determine to what extent 2-AG contributes to retrograde signaling, we generated and analyzed mutant mice lacking either of the two 2-AG synthesizing enzymes diacylglycerol lipase alpha (DGLalpha) and beta (DGLbeta). We found that endocannabinoid-mediated retrograde synaptic suppression was totally absent in the cerebellum, hippocampus, and striatum of DGLalpha knockout mice, whereas the retrograde suppression was intact in DGLbeta knockout brains. The basal 2-AG content was markedly reduced and stimulus-induced elevation of 2-AG was absent in DGLalpha knockout brains, whereas the 2-AG content was normal in DGLbeta knockout brains. Morphology of the brain and expression of molecules required for 2-AG production other than DGLs were normal in the two knockout mice. We conclude that 2-AG produced by DGLalpha, but not by DGLbeta, mediates retrograde suppression at central synapses.

Anaphylaxis is a life-threatening hyperacute immediate hypersensitivity reaction. Classically, it depends on IgE, FcεRI, mast cells, and histamine. However, anaphylaxis can also be induced by IgG antibodies, and an IgG1-induced passive type of systemic anaphylaxis has been reported to depend on basophils. In addition, it was found that neither mast cells nor basophils were required in mouse models of active systemic anaphylaxis. Therefore, we investigated what antibodies, receptors, and cells are involved in active systemic anaphylaxis in mice. We found that IgG antibodies, FcγRIIIA and FcγRIV, platelet-activating factor, neutrophils, and, to a lesser extent, basophils were involved. Neutrophil activation could be monitored in vivo during anaphylaxis. Neutrophil depletion inhibited active, and also passive, systemic anaphylaxis. Importantly, mouse and human neutrophils each restored anaphylaxis in anaphylaxis-resistant mice, demonstrating that neutrophils are sufficient to induce anaphylaxis in mice and suggesting that neutrophils can contribute to anaphylaxis in humans. Our results therefore reveal an unexpected role for IgG, IgG receptors, and neutrophils in anaphylaxis in mice. These molecules and cells could be potential new targets for the development of anaphylaxis therapeutics if the same mechanism is responsible for anaphylaxis in humans.

Polyunsaturated fatty acids (PUFAs) in phospholipids affect the physical properties of membranes, but it is unclear which biological processes are influenced by their regulation. For example, the functions of membrane arachidonate that are independent of a precursor role for eicosanoid synthesis remain largely unknown. Here, we show that the lack of lysophosphatidylcholine acyltransferase 3 (LPCAT3) leads to drastic reductions in membrane arachidonate levels, and that LPCAT3-deficient mice are neonatally lethal due to an extensive triacylglycerol (TG) accumulation and dysfunction in enterocytes. We found that high levels of PUFAs in membranes enable TGs to locally cluster in high density, and that this clustering promotes efficient TG transfer. We propose a model of local arachidonate enrichment by LPCAT3 to generate a distinct pool of TG in membranes, which is required for normal directionality of TG transfer and lipoprotein assembly in the liver and enterocytes.DOI: http://dx.doi.org/10.7554/eLife.06328.001

Summary Sox2 regulates the self-renewal of multiple types of stem cells. Recent studies suggest it also plays oncogenic roles in the formation of squamous carcinoma in several organs, including the esophagus where Sox2 is predominantly expressed in the basal progenitor cells of the stratified epithelium. Here, we use mouse genetic models to reveal a novel mechanism by which Sox2 cooperates with microenvironmental signals to malignantly transform epithelial progenitor cells. Conditional overexpression of Sox2 in basal cells expands the progenitor population in both the esophagus and forestomach. Significantly, carcinoma only develops in the forestomach where pathological progression correlates with inflammation and nuclear localization of Stat3 in progenitor cells. Importantly, co-overexpression of Sox2 and activated Stat3 (Stat3C) also transforms esophageal basal cells but not the differentiated suprabasal cells. These findings indicate basal stem/progenitor cells are the cells-of-origin of squamous carcinoma and that cooperation between Sox2 and microenvironment-activated Stat3 is required for Sox2-driven tumorigenesis.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease characterized by fibroblast proliferation and excess deposition of collagen and other extracellular matrix (ECM) proteins, which lead to distorted lung architecture and function. Given that anti-inflammatory or immunosuppressive therapy currently used for IPF does not improve disease progression therapies targeted to blocking the mechanisms of fibrogenesis are needed. Although transforming growth factor-beta (TGF-beta) functions are crucial in fibrosis, antagonizing this pathway in bleomycin-induced pulmonary fibrosis, an animal model of IPF, does not prevent fibrosis completely, indicating an additional pathway also has a key role in fibrogenesis. Given that the loss of cytosolic phospholipase A(2) (cPLA(2)) suppresses bleomycin-induced pulmonary fibrosis, we examined the roles of prostaglandins using mice lacking each prostoaglandin receptor. Here we show that loss of prostaglandin F (PGF) receptor (FP) selectively attenuates pulmonary fibrosis while maintaining similar levels of alveolar inflammation and TGF-beta stimulation as compared to wild-type (WT) mice, and that FP deficiency and inhibition of TGF-beta signaling additively decrease fibrosis. Furthermore, PGF(2alpha) is abundant in bronchoalveolar lavage fluid (BALF) of subjects with IPF and stimulates proliferation and collagen production of lung fibroblasts via FP, independently of TGF-beta. These findings show that PGF(2alpha)-FP signaling facilitates pulmonary fibrosis independently of TGF-beta and suggests this signaling pathway as a therapeutic target for IPF.