Ano1 as a regulator of proliferation

Ano1 is a recently discovered Ca(2+)-activated Cl(-) channel expressed on interstitial cells of Cajal (ICC) that has been implicated in slow-wave activity in the gut. However, Ano1 is expressed on all classes of ICC, even those that do not contribute to generation of the slow wave, suggesting that Ano1 may have an alternate function in these cells. Ano1 is also highly expressed in gastrointestinal stromal tumors. Mice lacking Ano1 had fewer proliferating ICC in whole mount preparations and in culture, raising the possibility that Ano1 is involved in proliferation. Cl(-) channel blockers decreased proliferation in cells expressing Ano1, including primary cultures of ICC and in the pancreatic cancer-derived cell line, CFPAC-1. Cl(-) channel blockers had a reduced effect on Ano1(-/-) cultures, confirming that the blockers are acting on Ano1. Ki67 immunoreactivity, 5-ethynyl-2'-deoxyuridine incorporation, and cell-cycle analysis of cells grown in low-Cl(-) media showed fewer proliferating cells than in cultures grown in regular medium. We confirmed that mice lacking Ano1 had less phosphorylated retinoblastoma protein compared with controls. These data led us to conclude that Ano1 regulates proliferation at the G(1)/S transition of the cell cycle and may play a role in tumorigenesis.     

Influence of +1245 A/G MT1A polymorphism on advanced glycation end-products (AGEs) in elderly: effect of zinc supplementation

Advanced glycation end-products (AGEs) stimulate reactive oxygen species (ROS) generation and represent a risk factor for atherosclerosis, while their formation seems to be prevented by zinc. Metallothioneins (MT), zinc-binding proteins exert an antioxidant function by regulating intracellular zinc availability and protecting cells from ROS damages. +1245 A/G MT1A polymorphism was implicated in type 2 diabetes and in cardiovascular disease development as well as in the modulation of antioxidant response. The purpose of this study was to investigate the influence of +1245 A/G MT1A polymorphism on AGEs and ROS production and to verify the effect of zinc supplementation on plasma AGEs, zinc status parameters and antioxidant enzyme activity in relation to this SNP. One hundred and ten healthy subjects (72 ± 6 years) from the ZincAge study were supplied with zinc aspartate (10 mg/day for 7 weeks) and screened for +1245 MT1A polymorphism. +1245 MT1A G+ (Arginine) genotype showed higher plasma AGEs and ROS production in peripheral blood mononuclear cells (PBMCs) than G− (Lysine) one at the baseline. No significant changes after zinc supplementation were observed for AGEs, ROS and MT levels as well as for enzyme antioxidant activity in relation to the genotype. Among zinc status parameters, major increases were observed for the intracellular labile zinc (iZnL) and the NO-induced release of zinc in PBMCs, in G+ genotype as compared to G− one. In summary, +1245 G+ carriers showed increased plasma AGEs and ROS production in PBMCs at baseline and a higher improvement in iZnL after zinc intervention with respect to G− individuals.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-014-0426-2) contains supplementary material, which is available to authorized users.     

Genetic Deletion of Mst1 Alters T Cell Function and Protects against Autoimmunity

Mammalian sterile 20-like kinase 1 (Mst1) is a MAPK kinase kinase kinase which is involved in a wide range of cellular responses, including apoptosis, lymphocyte adhesion and trafficking. The contribution of Mst1 to Ag-specific immune responses and autoimmunity has not been well defined. In this study, we provide evidence for the essential role of Mst1 in T cell differentiation and autoimmunity, using both genetic and pharmacologic approaches. Absence of Mst1 in mice reduced T cell proliferation and IL-2 production in vitro, blocked cell cycle progression, and elevated activation-induced cell death in Th1 cells. Mst1 deficiency led to a CD4⁺ T cell development path that was biased toward Th2 and immunoregulatory cytokine production with suppressed Th1 responses. In addition, Mst1^−/− B cells showed decreased stimulation to B cell mitogens in vitro and deficient Ag-specific Ig production in vivo. Consistent with altered lymphocyte function, deletion of Mst1 reduced the severity of experimental autoimmune encephalomyelitis (EAE) and protected against collagen-induced arthritis development. Mst1^−/− CD4⁺ T cells displayed an intrinsic defect in their ability to respond to encephalitogenic antigens and deletion of Mst1 in the CD4⁺ T cell compartment was sufficient to alleviate CNS inflammation during EAE. These findings have prompted the discovery of novel compounds that are potent inhibitors of Mst1 and exhibit desirable pharmacokinetic properties. In conclusion, this report implicates Mst1 as a critical regulator of adaptive immune responses, Th1/Th2-dependent cytokine production, and as a potential therapeutic target for immune disorders.     

Pituitary Adenylate Cyclase-Activating Polypeptide Ameliorates Experimental Acute Ileitis and Extra-Intestinal Sequelae

Background

The neuropeptide Pituitary adenylate cyclase-activating polypeptide (PACAP) plays pivotal roles in immunity and inflammation. So far, potential immune-modulatory properties of PACAP have not been investigated in experimental ileitis.

Methodology/Principal Findings

Mice were perorally infected with Toxoplasma (T.) gondii to induce acute ileitis (day 0) and treated daily with synthetic PACAP38 from day 1 to 6 post infection (p.i.; prophylaxis) or from day 4 to 6 p.i. (therapy). Whereas placebo-treated control mice suffered from acute ileitis at day 7 p.i. and succumbed to infection, intestinal immunopathology was ameliorated following PACAP prophylaxis. PACAP-treated mice exhibited increased abundance of small intestinal FOXP3+ cells, but lower numbers of ileal T lymphocytes, neutrophils, monocytes and macrophages, which was accompanied by less ileal expression of pro-inflammatory cytokines such as IL-23p19, IL-22, IFN-γ, and MCP-1. Furthermore, PACAP-treated mice displayed higher anti-inflammatory IL-4 concentrations in mesenteric lymph nodes and liver and higher systemic anti-inflammatory IL-10 levels in spleen and serum as compared to control animals at day 7 p.i. Remarkably, PACAP-mediated anti-inflammatory effects could also be observed in extra-intestinal compartments as indicated by reduced pro-inflammatory mediator levels in spleen (TNF-α, nitric oxide) and liver (TNF-α, IFN-γ, MCP-1, IL-6) and less severe histopathological sequelae in lungs and kidneys following prophylactic PACAP treatment. Strikingly, PACAP prolonged survival of T. gondii infected mice in a time-of-treatment dependent manner.

Conclusion/Significance

Synthetic PACAP ameliorates acute small intestinal inflammation and extra-intestinal sequelae by down-regulating Th1-type immunopathology, reducing oxidative stress and up-regulating anti-inflammatory cytokine responses. These findings provide novel potential treatment options of inflammatory bowel diseases.     

Pharmacological and Genetic Targeting of the PI4KA Enzyme Reveals Its Important Role in Maintaining Plasma Membrane Phosphatidylinositol 4-Phosphate and Phosphatidylinositol 4,5-Bisphosphate Levels

Phosphatidylinositol 4-kinase type IIIα (PI4KA) is a host factor essential for hepatitis C virus replication and hence is a target for drug development. PI4KA has also been linked to endoplasmic reticulum exit sites and generation of plasma membrane phosphoinositides. Here, we developed highly specific and potent inhibitors of PI4KA and conditional knock-out mice to study the importance of this enzyme in vitro and in vivo. Our studies showed that PI4KA is essential for the maintenance of plasma membrane phosphatidylinositol 4,5-bisphosphate pools but only during strong stimulation of receptors coupled to phospholipase C activation. Pharmacological blockade of PI4KA in adult animals leads to sudden death closely correlating with the drug''s ability to induce phosphatidylinositol 4,5-bisphosphate depletion after agonist stimulation. Genetic inactivation of PI4KA also leads to death; however, the cause in this case is due to severe intestinal necrosis. These studies highlight the risks of targeting PI4KA as an anti-hepatitis C virus strategy and also point to important distinctions between genetic and pharmacological studies when selecting host factors as putative therapeutic targets.     

Low birth weight, maternal birth-spacing decisions, and future reproduction

The aim of this study is an analysis of the possible adaptive consequences of delivery of low birth weight infants. We attempt to reveal the cost and benefit components of bearing small children, estimate the chance of the infants’ survival, and calculate the mothers’ reproductive success. According to life-history theory, under certain circumstances mothers can enhance their lifetime fitness by lowering the rate of investment in an infant and/or enhancing the rate of subsequent births. We assume that living in a risky environment and giving birth to a small infant may involve a shift from qualitative to quantitative production of offspring. Given high infant mortality rates, parents will have a reproductive interest in producing a relatively large number of children with a smaller amount of prenatal investment. This hypothesis was tested among 650 Gypsy and 717 non-Gypsy Hungarian mothers. Our study has revealed that 23.8% of the Gypsy mothers had low birth weight (<2,500 g) children, whose mortality rate is very high. These mothers also had more spontaneous abortions and stillbirths than those with normal weight children. As a possible response to these reproductive failures, they shortened birth spacing, gaining 2–4 years across their reproductive lifespan for having additional children. Because of the relatively short interbirth intervals, by the end of their fertility period, Gypsy mothers with one or two low birth weight infants have significantly more children than their ethnic Hungarian counterparts. They appear to compensate for handicaps associated with low birth weights by having a larger number of closely spaced children following the birth of one or more infants with a reduced probability of survival. The possible alternative explanations are discussed, and the long-term reproductive benefits are estimated for both ethnic groups.     

Digoxin Suppresses Pyruvate Kinase M2-Promoted HIF-1α Transactivation in Steatohepatitis

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