Severe Type 2 Inflammation Leads to High Platelet-Activating-Factor-Associated Pathology in Chronic Rhinosinusitis with Nasal Polyps-A Hierarchical Cluster Analysis Using Bulk RNA Barcoding and Sequencing.

Platelet-activating factor (PAF) is a phospholipid-derived inflammatory mediator that triggers various inflammatory conditions, including eosinophil activation and recruitment. This study aimed to evaluate the expressions of PAF-metabolism-associated genes, namely genes coding the enzymes involved in PAF synthesis (LPCAT1, LPCAT2, LPCAT3, and LPCAT4), PAF degradation (PAFAH1B2, PAFAH1B3, and PAFAH2), and the gene for the PAF receptor (PTAFR) in subtypes of CRSwNP classified by clinical- or hierarchal-analysis-based classifications. Transcriptomic analysis using bulk RNA barcoding and sequencing (BRB-seq) was performed with CRSwNP, including eosinophilic CRS (ECRS) (n = 9), nonECRS (n = 8), ECRS with aspirin-exacerbated respiratory disease (Asp) (n = 3), and controls with a normal uncinate process mucosa (n = 6). PTAFR was only upregulated in ECRS and nonECRS. In the hierarchical cluster analysis with clusters 1 and 2 reflecting patients with low-to-moderate and high levels of type 2 inflammation, respectively, cluster 1 exhibited a significant downregulation of LPCAT2 and an upregulation of PTAFR expression, while cluster 2 showed an upregulation of LPCAT1, PAFAH1B2, and PTAFR and downregulation of PAFAH2 expression. Understanding this strong PAF-associated pathophysiology in the severe type 2 inflammation group could provide valuable insights into the treatment and management of CRSwNP.

Keratinocyte-derived microvesicle particles mediate ultraviolet B radiation-induced systemic immunosuppression.

A complete carcinogen, ultraviolet B (UVB) radiation (290-320 nm), is the major cause of skin cancer. UVB-induced systemic immunosuppression that contributes to photocarcinogenesis is due to the glycerophosphocholine-derived lipid mediator platelet-activating factor (PAF). A major question in photobiology is how UVB radiation, which only absorbs appreciably in the epidermal layers of skin, can generate systemic effects. UVB exposure and PAF receptor (PAFR) activation in keratinocytes induce the release of large numbers of microvesicle particles (MVPs; extracellular vesicles ranging from 100 to 1000 nm in size). MVPs released from skin keratinocytes in vitro in response to UVB (UVB-MVPs) are dependent on the keratinocyte PAFR. Here, we used both pharmacologic and genetic approaches in cells and mice to show that both the PAFR and enzyme acid sphingomyelinase (aSMase) were necessary for UVB-MVP generation. Our discovery that the calcium-sensing receptor is a keratinocyte-selective MVP marker allowed us to determine that UVB-MVPs leaving the keratinocyte can be found systemically in mice and humans following UVB exposure. Moreover, we found that UVB-MVPs contained bioactive contents including PAFR agonists that allowed them to serve as effectors for UVB downstream effects, in particular UVB-mediated systemic immunosuppression.

Eicosanoid Signaling in Insect Immunology: New Genes and Unresolved Issues.

This paper is focused on eicosanoid signaling in insect immunology. We begin with eicosanoid biosynthesis through the actions of phospholipase A2, responsible for hydrolyzing the C18 polyunsaturated fatty acid, linoleic acid (18:2n-6), from cellular phospholipids, which is subsequently converted into arachidonic acid (AA; 20:4n-6) via elongases and desaturases. The synthesized AA is then oxygenated into one of three groups of eicosanoids, prostaglandins (PGs), epoxyeicosatrienoic acids (EETs) and lipoxygenase products. We mark the distinction between mammalian cyclooxygenases and insect peroxynectins, both of which convert AA into PGs. One PG, PGI2 (also called prostacyclin), is newly discovered in insects, as a negative regulator of immune reactions and a positive signal in juvenile development. Two new elements of insect PG biology are a PG dehydrogenase and a PG reductase, both of which enact necessary PG catabolism. EETs, which are produced from AA via cytochrome P450s, also act in immune signaling, acting as pro-inflammatory signals. Eicosanoids signal a wide range of cellular immune reactions to infections, invasions and wounding, including nodulation, cell spreading, hemocyte migration and releasing prophenoloxidase from oenocytoids, a class of lepidopteran hemocytes. We briefly review the relatively scant knowledge on insect PG receptors and note PGs also act in gut immunity and in humoral immunity. Detailed new information on PG actions in mosquito immunity against the malarial agent, Plasmodium berghei, has recently emerged and we treat this exciting new work. The new findings on eicosanoid actions in insect immunity have emerged from a very broad range of research at the genetic, cellular and organismal levels, all taking place at the international level.

COVID-19, microthromboses, inflammation, and platelet activating factor.

Recent articles report elevated markers of coagulation, endothelial injury, and microthromboses in lungs from deceased COVID-19 patients. However, there has been no discussion of what may induce intravascular coagulation. Platelets are critical in the formation of thrombi and their most potent trigger is platelet activating factor (PAF), first characterized by Demopoulos and colleagues in 1979. PAF is produced by cells involved in host defense and its biological actions bear similarities with COVID-19 disease manifestations. PAF can also stimulate perivascular mast cell activation, leading to inflammation implicated in severe acute respiratory syndrome (SARS). Mast cells are plentiful in the lungs and are a rich source of PAF and of inflammatory cytokines, such as IL-1ß and IL-6, which may contribute to COVID-19 and especially SARS. The histamine-1 receptor antagonist rupatadine was developed to have anti-PAF activity, and also inhibits activation of human mast cells in response to PAF. Rupatadine could be repurposed for COVID-19 prophylaxis alone or together with other PAF-inhibitors of natural origin such as the flavonoids quercetin and luteolin, which have antiviral, anti-inflammatory, and anti-PAF actions.

ROBO4 deletion ameliorates PAF-mediated skin inflammation via regulating the mRNA translation efficiency of LPCAT1/LPCAT2 and the expression of PAF receptor.

The diminished level of platelet-activating factor acetylhydrolase (PAFAH) in milk causes an enhanced level of platelet activating factor (PAF) in the skin, leading to a severe hair loss phenotype during neonatal pup's lactation. The deletion of very-low-density-lipoprotein receptor (VLDLR) prevents the expression and secretion of PAFAH. Here we revealed that deletion of Roundabout 4 (ROBO4) in mice ameliorated hair loss phenotype via reducing PAF concentration in skin. As a consequence, the neonatal pups with ROBO4 deletion lactated by mother with VLDLR deletion showed normal hair phenotype during lactation. In details,ROBO4 deletion reduced the protein but not mRNA expression of two PAF synthetic enzymes LPCAT1/LPCAT2 in macrophage as well as the expression of PAF receptor in both macrophage and ocular tissue, but increased PAFAH protein in serum. On the other hand, RNA expression profile analysis in macrophages revealed that the genes involving in oxidative phosphorylation and ribosome obviously decreased their expression in response to ROBO4 deletion. Moreover, through High Performance Liquid Chromatography (HPLC) analysis, we found that ATP concentration also reduced in ROBO4 deletion macrophages. Because ribosome and energy are very important factors for the mRNA translation, we then tested whether ROBO4 deletion affects LPCAT1/LPCAT2 mRNA translation using polyribosome assay. As expected, the mRNA level of LPCAT1/LPCAT2 significantly decreased in polyribosome in ROBO4 deletion macrophage comparing to that of wild type. Additionally, mice with ROBO4 deletion suppressed LPS-induced IL-6 expression as well as the phosphorylation of p44/42 and p65, but enhanced the AKT phosphorylation. Collectively, ROBO4 deletion alleviates PAF- and LPS-mediated inflammation. And above results also indicate PAF signal might be a crosstalk point of ROBO4- and VLDLR-activated pathways.

Hydroxysafflor yellow A (HSYA) targets the platelet-activating factor (PAF) receptor and inhibits human bronchial smooth muscle activation induced by PAF.

Hydroxysafflor yellow A (HSYA) is the main active ingredient of edible plant safflower. HSYA has demonstrated anti-inflammatory effects. The inflammatory response is the key mechanism responsible for asthma, and the pro-inflammatory platelet-activating factor (PAF) is known to play a role in the pathology of bronchial asthma. In this study, we stimulated human bronchial smooth muscle cells (HBSMCs) with PAF and examined the effects of HSYA on the resulting asthma-related process. PAF stimulation induced HBSMC activation, induced proliferation, increased expression of the pro-inflammatory cytokines interleukin (IL)-6, IL-1ß, and tumor necrosis factor-α, and activated asthma-related signaling pathways. All these effects were significantly inhibited by treatment with HSYA (9, 27, 81 µmol L-1). The effects of HSYA were prevented by the addition of a PAF receptor (PAFR) antagonist or by PAFR gene silencing with small interfering RNA. These results suggest that HSYA may inhibit PAF-induced activation of HBSMCs by targeting the PAFR. Overall, these findings provide evidence that HSYA can be applied as a potential therapeutic agent in the treatment of bronchial asthma.

Comparing the role of Ginkgolide B and Ginkgolide K on cultured astrocytes exposed to oxygen­glucose deprivation.

Ginkgolide B (GB) and ginkgolide K (GK) are two main active monomers of ginkgolides that present a unique group of diterpenes found naturally in the leaves of the Ginkgo biloba tree. Astrocytes are the most abundant cell type within the central nervous system (CNS) and serve essential roles in maintaining healthy brain function. The present study compared the biological effects of GB and GK on astrocytes exposed to oxygen­glucose deprivation (OGD). The results demonstrated that GB and GK exhibit many different actions. The level of the platelet­activating factor (PAF) was elevated on astrocytes exposed to OGD, and inhibited by GB and GK treatment. Although GB and GK inhibited the expression of p­NF­κB/p65, GK exerted stronger anti­inflammatory and antioxidant effects on astrocytes exposed to OGD than GB by inhibiting interleukin (IL)­6 and tumor necrosis factor­α, and inducing IL­10 and the nuclear factor­erythroid 2­related factor 2/HO­1 signaling pathway. When compared with GB treatment, GK treatment maintained high levels of phosphoinositide 3­kinase/phosphorylated­protein kinase B expression, and induced a marked upregulation of Wnt family member 1 and brain derived neurotrophic factor, indicating that GK, as a natural plant compound, may have more attractive prospects for clinical application in the treatment of neurological disorders than GB.

Peptidase Inhibitor 15 (PI15) Regulates Chlamydial CPAF Activity.

Obligate intracellular pathogenic Chlamydia trachomatis express several serine proteases whose roles in chlamydial development and pathogenicity are not completely understood. The chlamydial protease CPAF is expressed during the replicative phase of the chlamydial developmental cycle and is secreted into the lumen of the Chlamydia-containing vacuole called inclusion. How the secreted protease is activated in the inclusion lumen is currently not fully understood. We have identified human serine peptidase inhibitor PI15 as a potential host factor involved in the regulation of CPAF activation. Silencing expression as well as over expression of PI15 affected normal development of Chlamydia. PI15 was transported into the chlamydial inclusion lumen where it co-localized with CPAF aggregates. We show that PI15 binds to the CPAF zymogen and potentially induces CPAF protease activity at low concentrations. However, at high concentrations PI15 inhibits CPAF activity possibly by blocking its protease domain. Our findings shed light on a new aspect of chlamydial host co-evolution which involves the recruitment of host cell proteins into the inclusion to control the activation of bacterial proteases like CPAF that are important for the normal development of Chlamydia.

Relief from neuropathic pain by blocking of the platelet-activating factor-pain loop.

Neuropathic pain resulting from peripheral neuronal damage is largely resistant to treatment with currently available analgesic drugs. Recently, ATP, lysophosphatidic acid, and platelet-activating factor (PAF) have been reported to play important inductive roles in neuropathic pain. In the present study, we found that pain-like behaviors resulting from partial sciatic nerve ligation (PSL) were largely attenuated by deficiency of lysophosphatidylcholine acyltransferase (LPCAT)2, which is one of the PAF biosynthetic enzymes. By contrast, deficiency of the other PAF biosynthetic enzyme, LPCAT1, did not ameliorate neuropathic pain. With regard to the mechanism of the observed effects, LPCAT2 was detected in wild-type spinal cord microglia, and the absence of LPCAT2 expression precluded spinal PAF expression in LPCAT2-knockout mice. Furthermore, ATP-stimulated PAF biosynthesis in macrophages was decreased by pretreatment with the PAF receptor antagonist ABT-491, indicating the existence of a positive feedback loop of PAF biosynthesis, which we designated the PAF-pain loop. In conclusion, LPCAT2 is a novel therapeutic target for newly categorized analgesic drugs; in addition, our data call for the re-evaluation of the clinical utility of PAF receptor antagonists.-Shindou, H., Shiraishi, S., Tokuoka, S. M., Takahashi Y., Harayama, T., Abe, T., Bando, K., Miyano, K., Kita, Y., Uezono, Y., Shimizu, T. Relief from neuropathic pain by blocking of the platelet-activating factor-pain loop.

Analysis of the Serum Lipid Profile in Polypoidal Choroidal Vasculopathy.

Polypoidal choroidal vasculopathy (PCV), the predominant subtype of neovascular age-related macular degeneration in the Asian population, is associated with genetic polymorphism of lipid metabolism. In this study, we performed the untargeted lipidomics approach of ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS) to reveal the potential discriminating lipid profile of PCV patients in serum (21 PCV patients and 19 age-matched controls). Unsupervised principal component, supervised orthogonal partial least squares analysis, correlation analysis, and heatmap analysis were performed with the data obtained by UPLC-MS. Forty-one discriminating metabolites were identified. Receiver operating characteristic curve analysis, pathway analysis and functional analysis were performed subsequently, and platelet-activating factor (PAF) was further selected as the key indicator of the distinct lipid metabolism in PCV patients. Finally, the serum level of PAF was validated by enzyme-linked immunosorbent assay, which is significantly higher in PCV patients compared to controls (65 PCV patients and 63 age-matched controls, p < 0.0001), consistent with the UPLC-MS analysis. Our results suggested that PAF is considered as the major indicator of the distinct lipid metabolism in PCV patients.

Escherichia coli Braun Lipoprotein (BLP) exhibits endotoxemia - like pathology in Swiss albino mice.

The endotoxin lipopolysaccharide (LPS) promotes sepsis, but bacterial peptides also promote inflammation leading to sepsis. We found, intraperitoneal administration of live or heat inactivated E. coli JE5505 lacking the abundant outer membrane protein, Braun lipoprotein (BLP), was less toxic than E. coli DH5α possessing BLP in Swiss albino mice. Injection of BLP free of LPS purified from E. coli DH5α induced massive infiltration of leukocytes in lungs and liver. BLP activated human polymorphonuclear cells (PMNs) ex vivo to adhere to denatured collagen in serum and polymyxin B independent fashion, a property distinct from LPS. Both LPS and BLP stimulated the synthesis of platelet activating factor (PAF), a potent lipid mediator, in human PMNs. In mouse macrophage cell line, RAW264.7, while both BLP and LPS similarly upregulated TNF-α and IL-1ß mRNA; BLP was more potent in inducing cyclooxygenase-2 (COX-2) mRNA and protein expression. Peritoneal macrophages from TLR2-/- mice significantly reduced the production of TNF-α in response to BLP in contrast to macrophages from wild type mice. We conclude, BLP acting through TLR2, is a potent inducer of inflammation with a response profile both common and distinct from LPS. Hence, BLP mediated pathway may also be considered as an effective target against sepsis.

Dysfunctional epileptic neuronal circuits and dysmorphic dendritic spines are mitigated by platelet-activating factor receptor antagonism.

Temporal lobe epilepsy or limbic epilepsy lacks effective therapies due to a void in understanding the cellular and molecular mechanisms that set in motion aberrant neuronal network formations during the course of limbic epileptogenesis (LE). Here we show in in vivo rodent models of LE that the phospholipid mediator platelet-activating factor (PAF) increases in LE and that PAF receptor (PAF-r) ablation mitigates its progression. Synthetic PAF-r antagonists, when administered intraperitoneally in LE, re-establish hippocampal dendritic spine density and prevent formation of dysmorphic dendritic spines. Concomitantly, hippocampal interictal spikes, aberrant oscillations, and neuronal hyper-excitability, evaluated 15-16 weeks after LE using multi-array silicon probe electrodes implanted in the dorsal hippocampus, are reduced in PAF-r antagonist-treated mice. We suggest that over-activation of PAF-r signaling induces aberrant neuronal plasticity in LE and leads to chronic dysfunctional neuronal circuitry that mediates epilepsy.

Metabolomics of reef benthic interactions reveals a bioactive lipid involved in coral defence.

Holobionts are assemblages of microbial symbionts and their macrobial host. As extant representatives of some of the oldest macro-organisms, corals and algae are important for understanding how holobionts develop and interact with one another. Using untargeted metabolomics, we show that non-self interactions altered the coral metabolome more than self-interactions (i.e. different or same genus, respectively). Platelet activating factor (PAF) and Lyso-PAF, central inflammatory modulators in mammals, were major lipid components of the coral holobionts. When corals were damaged during competitive interactions with algae, PAF increased along with expression of the gene encoding Lyso-PAF acetyltransferase; the protein responsible for converting Lyso-PAF to PAF. This shows that self and non-self recognition among some of the oldest extant holobionts involve bioactive lipids identical to those in highly derived taxa like humans. This further strengthens the hypothesis that major players of the immune response evolved during the pre-Cambrian.

[Hypercoagulable state is associated with NF-kappa B activation and increased inflammatory factors in patients with rheumatoid arthritis].

OBJECTIVE: To investigate the mechanism of hypercoagulable state based on nuclear factor κB (NF-κB) pathway in patients with rheumatoid arthritis (RA). METHODS: Thirty-five RA patients were enrolled as well as 20 healthy volunteers as a control group. Interleukin-10 (IL-10), IL-6, IL-4, IL-17, NF-κB activator 1 (Act1), p50, p65, IκBα, platelet activating factor (PAF), PAF-acetylhydrolase (PAF-AH) and anti-cyclic citrullinated peptide (CCP) were detected using ELISA. The number of platelet (PLT) was detected using Sysmex XT-2000i automated hematology analyzer. The levels of D-dimer (D-D), fibrinogen (FBG), thrombin time (TT), prothrombin time (PT), and partial thromboplastin time (APTT) were detected using Sysmex CA-1500 automatic coagulation analyzer. Erythrocyte sedimentation rate (ESR) was detected using Westergren method. C-reactive protein and rheumatoid factor (RF) were detected using Hitachi 7060 automatic biochemical analyzer. Meanwhile, the mRNA expressions of Act1, p65, p50, IκBα and IκB kinase α (IKKα) were detected using semi-quantitative reverse transcription PCR. The expressions of p65, p50 and IκBα proteins were examined using Western blotting. The correlations of the above indexes were analyzed by Spearman correlation test. RESULTS: Compared with the normal group, the levels of DD, FBG, PLT significantly increased in the peripheral blood of RA patients, TT decreased, while APTT and PT were not significantly changed. IL-4, IL-10 and PAF-AH were significantly reduced in the sera of RA patients, while IL-6, IL-17, Act1, p50, p65, IκBα, IKKα and PAF were significantly elevated. Spearman correlation analysis showed that coagulant and fibrinolytic indexes were significantly correlated with cytokines, NF-κB, activity indexes and clinical symptoms and signs. CONCLUSION: The hypercoagulable state is common in the peripheral blood of RA patients, and it is closely related to inflammatory factors, activity indexes and abnormal activation of NF-κB.

UVB Generates Microvesicle Particle Release in Part Due to Platelet-activating Factor Signaling.

The lipid mediator platelet-activating factor (PAF) and oxidized glycerophosphocholine PAF agonists produced by ultraviolet B (UVB) have been demonstrated to play a pivotal role in UVB-mediated processes, from acute inflammation to delayed systemic immunosuppression. Recent studies have provided evidence that microvesicle particles (MVPs) are released from cells in response to various signals including stressors. Importantly, these small membrane fragments can interact with various cell types by delivering bioactive molecules. The present studies were designed to test if UVB radiation can generate MVP release from epithelial cells, and the potential role of PAF receptor (PAF-R) signaling in this process. We demonstrate that UVB irradiation of the human keratinocyte-derived cell line HaCaT resulted in the release of MVPs. Similarly, treatment of HaCaT cells with the PAF-R agonist carbamoyl PAF also generated equivalent amounts of MVP release. Of note, pretreatment of HaCaT cells with antioxidants blocked MVP release from UVB but not PAF-R agonist N-methyl carbamyl PAF (CPAF). Importantly, UVB irradiation of the PAF-R-negative human epithelial cell line KB and KB transduced with functional PAF-Rs resulted in MVP release only in PAF-R-positive cells. These studies demonstrate that UVB can generate MVPs in vitro and that PAF-R signaling appears important in this process.

Translation and Clinical Development of Antithrombotic Aptamers.

Thrombosis is a necessary physiological process to protect the body from uncontrolled bleeding. Pathological thrombus formation can lead to devastating clinical events including heart attack, stroke, deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation. Numerous drugs have been developed to inhibit thrombosis. These have been targeted to coagulation factors along with proteins and receptors that activate platelets. While these drugs are effective at preventing blood clotting, their major side effect is inadvertent hemorrhage that can result in significant morbidity and mortality. There exists a need for anticoagulants that are not only effective at preventing thrombosis but can also be readily reversed. Aptamers offer a potential solution, representing a new class of drug agents that can be isolated to any protein and where antidote oligonucleotides can be designed based on the sequence of the aptamer. We present a summary of the anticoagulant and antithrombotic aptamers that have been identified and their stage of development and comment on the future of aptamer-based drug development to treat thrombosis.

Platelets in patients with aspirin-exacerbated respiratory disease.

Aspirin-exacerbated respiratory disease (AERD) is a chronic inflammatory disease characterized clinically by the triad of asthma, nasal polyposis, and pathognomonic respiratory reactions after ingestion of aspirin. It is a distinct syndrome associated with eosinophilic infiltration of respiratory tissues and excessive production of cysteinyl leukotrienes. Despite the consistent clinical phenotype of the respiratory disease, the underlying pathogenesis of the disease remains unclear. In addition to their role in hemostasis, platelets have the capacity to influence the activation state and function of other immune cells during inflammation and to facilitate granulocyte recruitment into the tissues. Platelets also possess a repertoire of potent preformed mediators of inflammation that are released on activation and are a rich source of newly synthesized lipid mediators that alter vascular permeability and smooth muscle tone. Accordingly, platelet activity has been linked to diverse inflammatory diseases, including asthma. Both human and animal studies strongly suggest that platelet activity is uniquely associated with the pathophysiology of AERD. This article summarizes the evidence supporting an effector role for platelets in asthmatic patients in general and in patients with AERD in particular and considers the potential therapeutic implications.

Platelets in the immune response: Revisiting platelet-activating factor in anaphylaxis.

Anaphylaxis is an acute, severe, life-threatening multisystem allergic reaction resulting from the sudden systemic release of biochemical mediators and chemotactic substances. Release of both preformed granule-associated mediators and newly generated lipid-derived mediators contributes to the amplification and prolongation of anaphylaxis. Platelet-activating factor (PAF) is a potent phospholipid-derived mediator the central role of which has been well established in experimental models of both immune-mediated and non-immune mediated anaphylaxis. It is produced and secreted by several types of cells, including mast cells, monocytes, tissue macrophages, platelets, eosinophils, endothelial cells, and neutrophils. PAF is implicated in platelet aggregation and activation through release of vasoactive amines in the inflammatory response, resulting in increased vascular permeability, circulatory collapse, decreased cardiac output, and various other biological effects. PAF is rapidly hydrolyzed and degraded to an inactive metabolite, lysoPAF, by the enzyme PAF acetylhydrolase, the activity of which has shown to correlate inversely with PAF levels and predispose to severe anaphylaxis. In addition to its role in anaphylaxis, PAF has also been implicated as a mediator in both allergic and nonallergic inflammatory diseases, including allergic rhinitis, sepsis, atherosclerotic disease, and malignancy, in which PAF signaling has an established role. The therapeutic role of PAF antagonism has been investigated for several diseases, with variable results thus far. Further investigation of its role in pathology and therapeutic modulation is highly anticipated because of the pressing need for more selective and targeted therapy for the management of severe anaphylaxis.

Intracellular Ca2+ signaling and preimplantation development.

The key, versatile role of intracellular Ca2+ signaling during egg activation after fertilization has been appreciated for several decades. More recently, evidence has accumulated supporting the concept that cytoplasmic Ca2+ is also a major signaling nexus during subsequent development of the fertilized ovum. This chapter will review the molecular reactions that regulate intracellular Ca2+ levels and cell function, the role of Ca2+ signaling during egg activation and specific examples of repetitive Ca2+ signaling found throughout pre- and peri-implantation development. Many of the upstream and downstream pathways utilized during egg activation are also critical for specific processes that take place during embryonic development. Much remains to be done to elucidate the full complexity of Ca2+ signaling mechanisms in preimplantation embryos to the level of detail accomplished for egg activation. However, an emerging concept is that because this second messenger can be modulated downstream of numerous receptors and is able to bind and activate multiple cytoplasmic signaling proteins, it can help the coordination of development through up- and downstream pathways that change with each embryonic stage.

Hypoxia induces a lipogenic cancer cell phenotype via HIF1α-dependent and -independent pathways.

The biochemistry of cancer cells diverges significantly from normal cells as a result of a comprehensive reprogramming of metabolic pathways. A major factor influencing cancer metabolism is hypoxia, which is mediated by HIF1α and HIF2α. HIF1α represents one of the principal regulators of metabolism and energetic balance in cancer cells through its regulation of glycolysis, glycogen synthesis, Krebs cycle and the pentose phosphate shunt. However, less is known about the role of HIF1α in modulating lipid metabolism. Lipids serve cancer cells to provide molecules acting as oncogenic signals, energetic reserve, precursors for new membrane synthesis and to balance redox biological reactions. To study the role of HIF1α in these processes, we used HCT116 colorectal cancer cells expressing endogenous HIF1α and cells in which the hif1α gene was deleted to characterize HIF1α-dependent and independent effects on hypoxia regulated lipid metabolites. Untargeted metabolomics integrated with proteomics revealed that hypoxia induced many changes in lipids metabolites. Enzymatic steps in fatty acid synthesis and the Kennedy pathway were modified in a HIF1α-dependent fashion. Palmitate, stearate, PLD3 and PAFC16 were regulated in a HIF-independent manner. Our results demonstrate the impact of hypoxia on lipid metabolites, of which a distinct subset is regulated by HIF1α.