Molecular analysis of rat A3 adenosine receptor regulation

The regulatory effects of adenosine are dependent upon its ability to bind four distinct adenosine receptor (AR) subtypes termed A1, A2A, A2B and A3 (Ralevic and Bumstock, 1998). Despite coupling to the same class of inhibitory guanine nucleotide-binding regulatory protein (G-protein) and binding the same physiological ligand, the A1 and A3ARS are subject to distinct regulatory events following agonist exposure. Rapid termination of G protein-coupled receptor (GPCR) signalling is typically regulated by their phosphorylation by second messenger-activated and/or G protein-coupled receptor kinases (GRKs). Upon phosphorylation by G protein- coupled receptor kinases (GRKs), many GPCRs bind arrestin proteins that serve to uncouple activated receptors from G-proteins leading to a functional desensitisation of G protein-linked signalling, cluster activated receptors to clathrin-coated vesicles (CCVs) and recruit and activate Src family tyrosine kinases ultimately resulting in the activation of the mitogen activated protein kinase (MAPK) cascade. It is thought that receptors proceed from CCVs to endosomes where they may be dephosphorylated and recycled back to the plasma membrane or degraded and down- regulated. In this study, by employing the use of epitope and fluorescently tagged receptors, we show that agonist activation is required for A3AR phosphorylation and internalisation and that this process can be blocked by an A3AR-selective antagonist MRS 1523. We have characterised rates of A3AR internalisation and recycling and shown that it is dynamically controlled by three phosphorylation sites Thr 307, 318 and 319 and two presumed palmitoylation sites Cys 302 and 305 in its carboxyl- terminal (C) tail. Mutation of the Thr sites renders the receptor resistant to phosphorylation by GRKs, ultimately resulting in a loss of receptor sequestration compared to WT A3AR. In contrast, mutation of the Cys residues produces an increase in the rate of receptor internalisation compared to wild type (WT), a phenomenon not observed by the introduction of a similar mutation in the WT A1AR (Cys309Ala, data not shown). By the use of confocal microscopy, we reveal that despite their differences in trafficking rates, both WT and (C-A)A3ARs co-localise with transferrin (Tfn) receptor-positive early endosomes. We also demonstrate that this accumulation is dependent upon receptor phosphorylation as the non-internalising A1AR can be directed through this endosomal pathway by replacing the C-terminal tail with the GRK-phosphorylatable 14 amino acids of the A3AR (A1CT3AR). The process of receptor phosphorylation also dictates the pattern of arrestin distribution following agonist stimulation. A1AR activation caused a re-distribution of arrestin3 to distinct spots at the plasma membrane whereas WT A3AR, (C-A)A3AR and A1CT3 produced an accumulation of arrestin3 at both the plasma membrane and diffusely within the cytoplasm This study also demonstrates that long-term agonist exposure causes a down- regulation in total A3AR number via an as yet undefined pathway and may be directed by the C-terminal region of the receptor (Tsao and von Zastrow 2000b). Consequently, we have presented initial confocal images to suggest that recovery from down-regulation requires newly synthesised receptor to be transported from the Golgi apparatus to the plasma membrane

Intergenerational food-focused media literacy in Jamaica

Media use has been linked to unhealthy eating, but there is evidence that parent discussion about media and media literacy can inoculate against negative media effects. Therefore, we examined the relationships between mothers’ food-focused media literacy and their discussions about media and their adolescents’ food-focused media literacy in a survey of 82 mother-adolescent dyads in Jamaica, a middle-income country where obesity is rising. As expected, mothers’ food-focused media literacy was both greater than and positively related to their adolescents’ food-focused media literacy. The nature of the discussion (i.e., emotional intensity) about the time adolescents spent using media (TV, computer/electronics) positively related to adolescents’ media literacy. This study contributes to understanding how mothers may shape their adolescent’s media literacy and underscores the importance of considering parent-adolescent discussions for food-focused media literacy

Child Welfare, Domestic Violence And Substance Abuse: A Report on Protocols and Practices Preliminary Report

The purpose of the Project is to examine issues related to child abuse/neglect and substance abuse and domestic violence and substance abuse. In particular, the Project is interested in determining how the child welfare system and domestic violence programs interact with substance abuse services

Remote Acculturation 101: A Primer on Research, Implications, and Illustrations from Classrooms Around the World

Remote acculturation (RA) is a modern form of acculturation common among youth, which results from contact with a distant culture via the 4 Ts of globalization (trade, technology, tourism, and transnationalism). This article provides an introduction to RA by describing the what, who, how, where, and why of RA, summarizing its implications for youth development and health, and offering additional resources for student/classroom use. Utilizing our perspectives as psychology researchers and secondary school educators spanning 19 countries across Africa, Asia, Europe, North America, and South America, we supplement research findings from our lab and others with real-world illustrations from our classrooms around the globe. We conclude that the prominent role of media in RA presents cost-effective opportunities to promote its benefits (e.g., foreign media can sharpen cultural competence) and proactively buffer its risks (e.g., media literacy for inoculation against poor health habits)

Importance of Lipopolysaccharide and Cyclic β-1,2-Glucans in Brucella-Mammalian Infections

Brucella species are the causative agents of one of the most prevalent zoonotic diseases: brucellosis. Infections by Brucella species cause major economic losses in agriculture, leading to abortions in infected animals and resulting in a severe, although rarely lethal, debilitating disease in humans. Brucella species persist as intracellular pathogens that manage to effectively evade recognition by the host's immune system. Sugar-modified components in the Brucella cell envelope play an important role in their host interaction. Brucella lipopolysaccharide (LPS), unlike Escherichia coli LPS, does not trigger the host's innate immune system. Brucella produces cyclic β-1,2-glucans, which are important for targeting them to their replicative niche in the endoplasmic reticulum within the host cell. This paper will focus on the role of LPS and cyclic β-1,2-glucans in Brucella-mammalian infections and discuss the use of mutants, within the biosynthesis pathway of these cell envelope structures, in vaccine development