Aquaporin‐4 deficiency reduces TGF‐β1 in mouse midbrains and exacerbates pathology in experimental Parkinson's disease

Aquaporin‐4 (AQP4), the main water‐selective membrane transport protein in the brain, is localized to the astrocyte plasma membrane. Following the establishment of a 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐induced Parkinson's disease (PD) model, AQP4‐deficient (AQP4^?/?) mice displayed significantly stronger microglial inflammatory responses and remarkably greater losses of tyrosine hydroxylase (TH⁺)‐positive neurons than did wild‐type AQP4 (AQP4^+/+) controls. Microglia are the most important immune cells that mediate immune inflammation in PD. However, recently, few studies have reported why AQP4 deficiency results in more severe hypermicrogliosis and neuronal damage after MPTP treatment. In this study, transforming growth factor‐β1 (TGF‐β1), a key suppressive cytokine in PD onset and development, failed to increase in the midbrain and peripheral blood of AQP4^?/? mice after MPTP treatment. Furthermore, the lower level of TGF‐β1 in AQP4^?/? mice partially resulted from impairment of its generation by astrocytes; reduced TGF‐β1 may partially contribute to the uncontrolled microglial inflammatory responses and subsequent severe loss of TH⁺ neurons in AQP4^?/? mice after MPTP treatment. Our study provides not only a better understanding of both aetiological and pathogenical factors implicated in the neurodegenerative mechanism of PD but also a possible approach to developing new treatments for PD via intervention in AQP4‐mediated immune regulation.     

Prostaglandin I2 upregulates the expression of anterior pharynx‐defective‐1α and anterior pharynx‐defective‐1β in amyloid precursor protein/presenilin 1 transgenic mice

Cyclooxygenase‐2 (COX‐2) has been recently identified to be involved in the pathogenesis of Alzheimer's disease (AD). Yet, the role of an important COX‐2 metabolic product, prostaglandin (PG) I₂, in the pathogenesis of AD remains unknown. Using human‐ and mouse‐derived neuronal cells as well as amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice as model systems, we elucidated the mechanism of anterior pharynx‐defective (APH)‐1α and pharynx‐defective‐1β induction. In particular, we found that PGI₂ production increased during the course of AD development. Then, PGI₂ accumulation in neuronal cells activates PKA/CREB and JNK/c‐Jun signaling pathways by phosphorylation, which results in APH‐1α/1β expression. As PGI₂ is an important metabolic by‐product of COX‐2, its suppression by NS398 treatment decreases the expression of APH‐1α/1β in neuronal cells and APP/PS1 mice. More importantly, β‐amyloid protein (Aβ) oligomers in the cerebrospinal fluid (CSF) of APP/PS1 mice are critical for stimulating the expression of APH‐1α/1β, which was blocked by NS398 incubation. Finally, the induction of APH‐1α/1β was confirmed in the brains of patients with AD. Thus, these findings not only provide novel insights into the mechanism of PGI₂‐induced AD progression but also are instrumental for improving clinical therapies to combat AD.     

Ecological immunity of human milk: Life history perspectives from the United States and Kenya

Objectives

Previous research has established population variation in anti‐inflammatory immunological biomarkers in human milk. This immunity is potentially ecology‐dependent and may alter the life history trade‐off between growth and maintenance in infants. The current study has two aims: (1) to assess the ecological differences in milk immunity in two populations, one from the urban U.S. and one from rural Kenya; and (2) to test the hypothesis that milk immunity can affect infant growth indicators.

Materials and Methods

Kenyan Ariaal (n = 233) and U.S. (n = 75) breastfeeding mother‐infant pairs participated in a cross‐sectional study at two separate field sites. Laboratory analysis was performed on milk for the anti‐inflammatory biomarkers TGF‐β2, sTNF‐αRI, sTNF‐αRII, and IL‐1ra using ELISA. Multiple imputation was used to extrapolate data below the limit of detection before multivariate analysis.

Results

There were significant differences between U.S. and Kenyan mothers on all four milk biomarkers, with Kenyan mothers having significantly higher sTNF‐αRI and sTNF‐αRII and lower TGF‐β2 and IL‐1ra than U.S. mothers. U.S. mothers with higher milk TGF‐β2 and IL‐1ra have infants that are significantly longer and heavier for their age, while Kenyan mothers with higher sTNF‐αRI have significantly longer and heavier infants for their age, and those with higher TGF‐β2 have marginally significantly longer infants.

Discussion

There were significant differences in ecological milk immunity between U.S. and Kenyan mothers. These differences potentially play a role in the growth of their infants. Further research in milk immunity should consider the possibility of shared maternal–infant life histories.

     

Activation of the NLRP3 inflammasome in microglia: the role of ceramide

Inflammation within the CNS is a major component of many neurodegenerative diseases. A characteristic feature is the generation of microglia‐derived factors that play an essential role in the immune response. IL‐1β is a pro‐inflammatory cytokine released by activated microglia, able to exacerbate injury at elevated levels. In the presence of caspase‐1, pro‐IL‐1β is cleaved to the mature cytokine following NOD‐like receptor pyrin domain containing 3 (NLRP3) inflammasome activation. Growing evidence suggests that ceramide plays a critical role in NLRP3 inflammasome assembly, however, the relationship between ceramide and inflammasome activation in microglia remains unknown. Here, we investigated potential mechanistic links between ceramide as a modulator of NLRP3 inflammasome assembly and the resulting secretion of IL‐1β using small bioactive enzyme stimulators and inhibitors of ceramide signaling in wild‐type and apoptosis‐associated speck‐like protein containing a CARD knockout (ASC^?/?) primary microglia. To induce the expression of inflammasome components, microglia were primed prior to experiments. Treatment with sodium palmitate (PA) induced de novo ceramide synthesis via modulation of its synthesizing protein serine palmitoyl transferase resulting in increased IL‐1β secretion in microglia. Exposure of microglia to the serine palmitoyl transferase‐inhibitor l ‐cycloserine significantly prevented PA‐induced IL‐1β secretion. Application of the ceramide analogue C2 and the sphingosine‐1‐phosphate‐receptor agonist Fingolimod (FTY720) up‐regulated levels of IL‐1β and cleaved caspase‐1 in wild‐type microglia, whereas ASC^?/? microglia were unaffected. HPA‐12 inhibition of ceramide transport did not affect inflammasome activation. Taken together, our findings reveal a critical role for ceramide as a positive modulator of NLRP3 inflammasome assembly and the resulting release of IL‐1β.

     

Synthesis of β‐Ketoamide Curcumin Analogs for Anti‐Diabetic and AGEs Inhibitory Activities

Two different series of novel β‐ketoamide curcumin analogs enriched in biological activities have been synthesized. The synthesized compounds were screened for their in vitro anti‐diabetic and AGEs inhibitory activities and exhibited potent to good anti‐diabetic and AGEs inhibitory activities. The molecular docking study was also performed with the α‐amylase enzyme.     

Posttranslational modification impact on the mechanism by which amyloid‐β induces synaptic dysfunction

Oligomeric amyloid‐β (Aβ) 1‐42 disrupts synaptic function at an early stage of Alzheimer's disease (AD). Multiple posttranslational modifications of Aβ have been identified, among which N‐terminally truncated forms are the most abundant. It is not clear, however, whether modified species can induce synaptic dysfunction on their own and how altered biochemical properties can contribute to the synaptotoxic mechanisms. Here, we show that a prominent isoform, pyroglutamated Aβ3(pE)‐42, induces synaptic dysfunction to a similar extent like Aβ1‐42 but by clearly different mechanisms. In contrast to Aβ1‐42, Aβ3(pE)‐42 does not directly associate with synaptic membranes or the prion protein but is instead taken up by astrocytes and potently induces glial release of the proinflammatory cytokine TNFα. Moreover, Aβ3(pE)‐42‐induced synaptic dysfunction is not related to NMDAR signalling and Aβ3(pE)‐42‐induced impairment of synaptic plasticity cannot be rescued by D1‐agonists. Collectively, the data point to a scenario where neuroinflammatory processes together with direct synaptotoxic effects are caused by posttranslational modification of soluble oligomeric Aβ and contribute synergistically to the onset of synaptic dysfunction in AD.     

Synthesis and receptor binding of opioid peptide analogues containing β3‐homo‐amino acids

β‐Amino acids containing hybrid peptides and β‐peptides show great potential as peptidomimetics. In this paper we describe the synthesis and affinity toward the µ‐ and δ‐opioid receptors of β‐peptides, analogues of Leu‐enkephalin, deltorphin I, dermorphin and α,β‐hybrides, analogues of deltorphin I. Substitution of α‐amino acid residues with β³‐homo‐amino acid residues, in general resulted in decrease of affinity to opioid receptors. However, the incorporation β³h‐D ‐Ala in position 2 or β³hPhe in position 3 of deltorphin I resulted in potent and selective ligand for δ‐opioid receptor. The NMR studies of β‐deltorphin I analogue suggest that conformational motions in the central part of the peptide backbone are partially restricted and some conformational preferences can be expected. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.     

A novel approach to predicting protein structural classes in a (20–1)-D amino acid composition space

The development of prediction methods based on statistical theory generally consists of two parts: one is focused on the exploration of new algorithms, and the other on the improvement of a training database. The current study is devoted to improving the prediction of protein structural classes from both of the two aspects. To explore a new algorithm, a method has been developed that makes allowance for taking into account the coupling effect among different amino acid components of a protein by a covariance matrix. To improve the training database, the selection of proteins is carried out so that they have (1) as many non-homologous structures as possible, and (2) a good quality of structure. Thus, 129 representative proteins are selected. They are classified into 30 α, 30 β, 30 α + β, 30 α/β, and 9 ζ (irregular) proteins according to a new criterion that better reflects the feature of the structural classes concerned. The average accuracy of prediction by the current method for the 4 × 30 regular proteins is 99.2%, and that for 64 independent testing proteins not included in the training database is 95.3%. To further validate its efficiency, a jackknife analysis has been performed for the current method as well as the previous ones, and the results are also much in favor of the current method. To complete the mathematical basis, a theorem is presented and proved in Appendix A that is instructive for understanding the novel method at a deeper level. © 1995 Wiley-Liss, Inc.     

Characterization of an Importin α/β‐recognized nuclear localization signal in β‐dystroglycan

β‐dystroglycan (β‐DG) is a widely expressed transmembrane protein that plays important roles in connecting the extracellular matrix to the cytoskeleton, and thereby contributing to plasma membrane integrity and signal transduction. We previously observed nuclear localization of β‐DG in cultured cell lines, implying the existence of a nuclear targeting mechanism that directs it to the nucleus instead of the plasma membrane. In this study, we delineate the nuclear import pathway of β‐DG, characterizing a functional nuclear localization signal (NLS) in the β‐DG cytoplasmic domain, within amino acids 776–782. The NLS either alone or in the context of the whole β‐DG protein was able to target the heterologous GFP protein to the nucleus, with site‐directed mutagenesis indicating that amino acids R⁷⁷⁹ and K⁷⁸⁰ are critical for NLS functionality. The nuclear transport molecules Importin (Imp)α and Impβ bound with high affinity to the NLS of β‐DG and were found to be essential for NLS‐dependent nuclear import in an in vitro reconstituted nuclear transport assay; cotransfection experiments confirmed the dependence on Ran for nuclear accumulation. Intriguingly, experiments suggested that tyrosine phosphorylation of β‐DG may result in cytoplasmic retention, with Y⁸⁹² playing a key role. β‐DG thus follows a conventional Impα/β‐dependent nuclear import pathway, with important implications for its potential function in the nucleus. J. Cell. Biochem. 110: 706–717, 2010. © 2010 Wiley‐Liss, Inc.     

The importance of starch and sucrose digestion in nutritive biology of synanthropic acaridid mites: α‐Amylases and α‐glucosidases are suitable targets for inhibitor‐based strategies of mite control

The adaptation of nine species of mites that infest stored products for starch utilization was tested by (1) enzymatic analysis using feces and whole mite extracts, (2) biotests, and (3) inhibition experiments. Acarus siro, Aleuroglyphus ovatus, and Tyroborus lini were associated with the starch‐type substrates and maltose, with higher enzymatic activities observed in whole mite extracts. Lepidoglyphus destructor was associated with the same substrates but had higher activities in feces. Dermatophagoides farinae, Chortoglyphus arcuatus, and Caloglyphus redickorzevi were associated with sucrose. Tyrophagus putrescentiae and Carpoglyphus lactis had low or intermediate enzymatic activity on the tested substrates. Biotests on starch additive diets showed accelerated growth of species associated with the starch‐type substrates. The inhibitor acarbose suppressed starch hydrolysis and growth of the mites. We suggest that the species with higher starch hydrolytic activity in feces were more tolerant to acarbose, and α‐amylase and α‐glucosidase of synanthropic mites are suitable targets for inhibitor‐based strategies of mite control. © 2009 Wiley Periodicals, Inc.     

Phosphatidylinositol‐3‐OH kinase regulatory subunits are differentially expressed during development of the rat cerebellum

Recent evidence implicates a central role for PI3K signalling in mediating cell survival during the process of neuronal differentiation. Although PI3K activity is stimulated by a wide range of growth factors and cytokines in different cell lines and tissues, activation of this pathway by insulin‐like growth factor I (IGF‐I) most likely represents the main survival signal during neuronal differentiation. IGF‐I is highly expressed during development of the central nervous system, and thus is a critical factor for the development and maturation of the cerebellum. Upon ligand binding, the IGF‐I receptor phosphorylates tyrosine residues in SHC and insulin receptor substrates (IRSs) initiating two main signalling cascades, the MAP kinase and the phosphatidylinositol 3‐kinase (PI3K) pathways. Activated PI3K is composed of a catalytic subunit (p110α or β) associated with one of a large family of regulatory subunits (p85α, p85β, p55γ, p55α, and p50α). To evaluate the contributions of these various regulatory subunits to neuronal differentiation, we have used antibodies specific for each of the PI3K subunits. Using these antisera, we now demonstrate that PI3K subunits are differentially regulated in cerebellar development, and that the expression level of the p55γ regulatory subunit reaches a maximum during postnatal development, decreasing thereafter to low levels in the adult cerebellum. Furthermore, our studies reveal that the distribution of the various PI3K regulatory subunits varies during development of the cerebellum. Interestingly, p55γ is expressed in both glial and neuronal cells; moreover, in Purkinje neurones, this subunit colocalises with the IGF‐IR. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 39–50, 2001     

IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis

Inflammatory cytokines are closely related to pigmentary changes. In this study, the effects of IFN‐γ on melanogenesis were investigated. IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis in B16 melanoma cells and normal human melanocytes. MITF mRNA and protein expressions were significantly inhibited in response to IFN‐γ. IFN‐γ inhibited CREB binding to the MITF promoter but did not affect CREB phosphorylation. Instead, IFN‐γ inhibited the association of CBP and CREB through the increased association between CREB binding protein (CBP) and STAT1. These findings suggest that IFN‐γ inhibits both basal and α‐MSH‐induced melanogenesis by inhibiting MITF expression. The inhibitory action of IFN‐γ in α‐MSH‐induced melanogenesis is likely to be associated with the sequestration of CBP via the association between CBP and STAT1. These data suggest that IFN‐γ plays a role in controlling inflammation‐ or UV‐induced pigmentary changes.