Multisite phosphorylation dictates selective E2-E3 pairing as revealed by Ubc8/UBE2H-GID/CTLH assemblies.

Ubiquitylation is catalyzed by coordinated actions of E3 and E2 enzymes. Molecular principles governing many important E3-E2 partnerships remain unknown, including those for RING-family GID/CTLH E3 ubiquitin ligases and their dedicated E2, Ubc8/UBE2H (yeast/human nomenclature). GID/CTLH-Ubc8/UBE2H-mediated ubiquitylation regulates biological processes ranging from yeast metabolic signaling to human development. Here, cryoelectron microscopy (cryo-EM), biochemistry, and cell biology reveal this exquisitely specific E3-E2 pairing through an unconventional catalytic assembly and auxiliary interactions 70-100 Å away, mediated by E2 multisite phosphorylation. Rather than dynamic polyelectrostatic interactions reported for other ubiquitylation complexes, multiple Ubc8/UBE2H phosphorylation sites within acidic CK2-targeted sequences specifically anchor the E2 C termini to E3 basic patches. Positions of phospho-dependent interactions relative to the catalytic domains correlate across evolution. Overall, our data show that phosphorylation-dependent multivalency establishes a specific E3-E2 partnership, is antagonistic with dephosphorylation, rigidifies the catalytic centers within a flexing GID E3-substrate assembly, and facilitates substrate collision with ubiquitylation active sites.

Body mass index trajectories and their predictors in undergraduate students from Canada: Results from the GENEiUS study.

Objective: To explore the patterns and predictors of body mass index (BMI) change among undergraduate students from Ontario (Canada). Participants: 68 undergraduate students were followed longitudinally for 3 years with anthropometric data collected bi-annually. Methods: BMI measurements were plotted to generate individual BMI trajectory curves, which were categorized, based on the observed trajectory pattern. Within and between group comparisons of BMI were conducted via nonparametric paired tests. The association of baseline BMI, sex, and ethnicity with BMI trajectory type was assessed using multinomial logistic regression. Results: Four BMI trajectory types were observed: "stable weight" (n = 15, 22.1%), "weight gain" (n = 30, 44.1%), "weight loss" (n = 12, 17.6%), and "weight cycling" (n = 11, 16.2%) trajectories. Higher baseline BMI was significantly associated with the "weight gain," "weight loss," and the "weight cycling" trajectories as compared to the "stable weight" trajectory type. Conclusions: Our findings demonstrate an association between high baseline BMI and "nonstable" subsequent BMI change patterns among Canadian students.

A GID E3 ligase assembly ubiquitinates an Rsp5 E3 adaptor and regulates plasma membrane transporters.

Cells rapidly remodel their proteomes to align their cellular metabolism to environmental conditions. Ubiquitin E3 ligases enable this response, by facilitating rapid and reversible changes to protein stability, localization, or interaction partners. In Saccharomyces cerevisiae, the GID E3 ligase regulates the switch from gluconeogenic to glycolytic conditions through induction and incorporation of the substrate receptor subunit Gid4, which promotes the degradation of gluconeogenic enzymes. Here, we show an alternative substrate receptor, Gid10, which is induced in response to changes in temperature, osmolarity, and nutrient availability, regulates the ART-Rsp5 ubiquitin ligase pathway, a component of plasma membrane quality control. Proteomic studies reveal that the levels of the adaptor protein Art2 are elevated upon GID10 deletion. A crystal structure shows the basis for Gid10-Art2 interactions, and we demonstrate that Gid10 directs a GID E3 ligase complex to ubiquitinate Art2. Our data suggest that the GID E3 ligase affects Art2-dependent amino acid transport. This study reveals GID as a system of E3 ligases with metabolic regulatory functions outside of glycolysis and gluconeogenesis, controlled by distinct stress-specific substrate receptors.

GID E3 ligase supramolecular chelate assembly configures multipronged ubiquitin targeting of an oligomeric metabolic enzyme.

How are E3 ubiquitin ligases configured to match substrate quaternary structures? Here, by studying the yeast GID complex (mutation of which causes deficiency in glucose-induced degradation of gluconeogenic enzymes), we discover supramolecular chelate assembly as an E3 ligase strategy for targeting an oligomeric substrate. Cryoelectron microscopy (cryo-EM) structures show that, to bind the tetrameric substrate fructose-1,6-bisphosphatase (Fbp1), two minimally functional GID E3s assemble into the 20-protein Chelator-GIDSR4, which resembles an organometallic supramolecular chelate. The Chelator-GIDSR4 assembly avidly binds multiple Fbp1 degrons so that multiple Fbp1 protomers are simultaneously ubiquitylated at lysines near the allosteric and substrate binding sites. Importantly, key structural and biochemical features, including capacity for supramolecular assembly, are preserved in the human ortholog, the CTLH E3. Based on our integrative structural, biochemical, and cell biological data, we propose that higher-order E3 ligase assembly generally enables multipronged targeting, capable of simultaneously incapacitating multiple protomers and functionalities of oligomeric substrates.

Effect of sex/gender on obesity traits in Canadian first year university students: The GENEiUS study.

BACKGROUND: While weight gain during first year of university has been well documented in North America, literature on sex-specific effects is scarce and inconsistent. The objective of this investigation was to explore sex-specific changes in obesity traits during first year of university at McMaster University (Ontario, Canada). METHODS: 245 first-year students (80.4% females) were followed longitudinally with data collected early in the academic year and towards the end of the year. Obesity parameters including weight, waist and hip circumferences, BMI, and waist to hip ratio were investigated. The Mann-Whitney U test and the Wilcoxon signed-rank test were used for pairwise comparison of traits in the absence of adjustments. Additionally, the repeated-measures ANOVA test was used with covariate adjustments to investigate the interaction between sex and time. RESULTS: Overall sample trends indicated a significant increase in mean weight by 1.55 kg (95% CI: 1.24-1.86) over the school year (p<0.001). This was accompanied by significant gains in BMI, and waist and hip circumferences (p<0.001) in the overall sample. At baseline, males presented with higher body weight, BMI, waist and hip circumferences, and WHR, as compared to their females counterparts (p<0.01). Additionally, sex-stratified analysis indicated significant gains in weight, BMI, and waist and hip circumferences in both males and females (p<0.01). However, a comparison of the magnitude of change over time between the two sex groups revealed no significant difference for any of the investigated traits (p>0.05). CONCLUSION: While our study confirms significant weight gain in both male and female first year university students in Ontario, Canada, it does not show sex specific differences within this context. Our investigation highlights the importance of accounting for sex and gender in health research and supports the need of further studies in this area.

Engaging patients as partners in a multicentre trial of spinal versus general anaesthesia for older adults.

Engaging patients-defined broadly as individuals with lived experience of a given condition, family members, caregivers, and the organisations that represent them-as partners in research is a priority for policymakers, funders, and the public. Nonetheless, formal efforts to engage patients are absent from most studies, and models to support meaningful patient engagement in clinical anaesthesia research have not been previously described. Here, we review our experience in developing and implementing a multifaceted patient engagement strategy within the Regional Versus General Anesthesia for Promoting Independence After Hip Fracture (REGAIN) surgery trial, an ongoing randomised trial comparing spinal vs general anaesthesia for hip fracture surgery in 1600 older adults across 45 hospitals in the USA and Canada. This strategy engaged patients and their representatives at both the level of overall trial oversight and at the level of individual recruiting sites. Activities spanned a continuum ranging from events designed to elicit patients' input on key decisions to longitudinal collaborations that empowered patients to actively participate in decision-making related to trial design and management. Engagement activities were highly acceptable to participants and led to concrete changes in the design and conduct of the REGAIN trial. The REGAIN experience offers a model for future efforts to engage patients as partners in clinical anaesthesia research, and highlights potential opportunities for investigators to increase the relevance of anaesthesia studies by incorporating patient voices and perspectives into the research process.

DIA-based systems biology approach unveils E3 ubiquitin ligase-dependent responses to a metabolic shift.

The yeast Saccharomyces cerevisiae is a powerful model system for systems-wide biology screens and large-scale proteomics methods. Nearly complete proteomics coverage has been achieved owing to advances in mass spectrometry. However, it remains challenging to scale this technology for rapid and high-throughput analysis of the yeast proteome to investigate biological pathways on a global scale. Here we describe a systems biology workflow employing plate-based sample preparation and rapid, single-run, data-independent mass spectrometry analysis (DIA). Our approach is straightforward, easy to implement, and enables quantitative profiling and comparisons of hundreds of nearly complete yeast proteomes in only a few days. We evaluate its capability by characterizing changes in the yeast proteome in response to environmental perturbations, identifying distinct responses to each of them and providing a comprehensive resource of these responses. Apart from rapidly recapitulating previously observed responses, we characterized carbon source-dependent regulation of the GID E3 ligase, an important regulator of cellular metabolism during the switch between gluconeogenic and glycolytic growth conditions. This unveiled regulatory targets of the GID ligase during a metabolic switch. Our comprehensive yeast system readout pinpointed effects of a single deletion or point mutation in the GID complex on the global proteome, allowing the identification and validation of targets of the GID E3 ligase. Moreover, this approach allowed the identification of targets from multiple cellular pathways that display distinct patterns of regulation. Although developed in yeast, rapid whole-proteome-based readouts can serve as comprehensive systems-level assays in all cellular systems.

The effect of race/ethnicity on obesity traits in first year university students from Canada: The GENEiUS study.

BACKGROUND: Little is known about the impact of race/ethnicity on weight change at university. The objective of this study is to determine if ethnicity has an impact on obesity traits in a multiethnic cohort of first-year students at McMaster University in Ontario, Canada. METHODS: 183 first year students from the three most represented ethnic groups (South Asian, East Asian, and white-Caucasian) in our study sample were followed longitudinally with data collected early in the academic year and towards the end of the year. Obesity parameters including body weight, body mass index (BMI), waist and hip circumference, and waist hip ratio (WHR) were analyzed. The Wilcoxon signed-rank test was used for pairwise comparison of traits from the beginning to the end of the year in the absence of adjustments. Linear regression was used with covariate adjustments to investigate the effect of ethnicity on obesity traits. RESULTS: A significant increase in weight by 1.49 kg (95%CI: 1.13-1.85) was observed over the academic year in the overall analyzed sample. This was accompanied by significant gains in BMI, waist and hip circumferences, and WHR. Ethnicity stratified analysis indicated significant increase in all investigated obesity traits in East Asians and all traits, but WHR, in South Asians. White-Caucasians only displayed significant increases in weight and BMI. Body weight and hip circumference were significantly lower in East Asians compared to white-Caucasians at baseline. However, East Asians displayed a significantly larger increase in mean BMI and weight compared to white-Caucasians after first-year. South Asians displayed larger waist circumference at baseline compared to East Asians and larger WHR compared to white-Caucasians. CONCLUSION: Our findings demonstrate that ethnicity has an impact on obesity traits in first-year university students. Universities should take ethnicity into account while implementing effective obesity prevention programs to promote healthy and active lifestyles for students.

Effect of living arrangement on anthropometric traits in first-year university students from Canada: The GENEiUS study.

BACKGROUND: The transition to university often involves a change in living arrangement for many first-year students. While weight gain during first year of university has been well documented, Canadian literature on the impact of living arrangement within this context is limited. The objective of this investigation was to explore the effect of living arrangement on anthropometric traits in first-year university students from Ontario, Canada. METHODS: 244 first-year undergraduate students were followed longitudinally with data collected early in the academic year and towards the end of the year. Anthropometric parameters including weight, waist and hip circumference, body mass index (BMI), and waist-to-hip ratio (WHR) were examined. The Wilcoxon signed-rank test was used for pairwise comparison of traits from the beginning to end the year in the absence of adjustments. Additionally, linear regression models with covariate adjustments were used to investigate effect of the type of living arrangement (i.e. on-campus, off-campus, or family home) on the aforementioned traits. RESULTS: In the overall sample, a significant weight increase of 1.55kg (95% CI: 1.24-1.86) was observed over the school year (p<0.001), which was also accompanied by significant gains in BMI, and waist and hip circumferences (p<0.001). At baseline, no significant differences were found between people living on-campus, off-campus, and at home with family. Stratified analysis of change by type of living arrangement indicated significant gains across all traits among students living on-campus (p<0.05), and significant gains in weight and BMI among students living at home with family. Additionally, a comparison between living arrangements revealed that students living on campus experienced significantly larger gains in weight and BMI compared to students living off-campus (p<0.05). CONCLUSION: Our findings indicate that living arrangement is associated with different weight gain trajectories in first-year university students.

Interconversion between Anticipatory and Active GID E3 Ubiquitin Ligase Conformations via Metabolically Driven Substrate Receptor Assembly.

Cells respond to environmental changes by toggling metabolic pathways, preparing for homeostasis, and anticipating future stresses. For example, in Saccharomyces cerevisiae, carbon stress-induced gluconeogenesis is terminated upon glucose availability, a process that involves the multiprotein E3 ligase GIDSR4 recruiting N termini and catalyzing ubiquitylation of gluconeogenic enzymes. Here, genetics, biochemistry, and cryoelectron microscopy define molecular underpinnings of glucose-induced degradation. Unexpectedly, carbon stress induces an inactive anticipatory complex (GIDAnt), which awaits a glucose-induced substrate receptor to form the active GIDSR4. Meanwhile, other environmental perturbations elicit production of an alternative substrate receptor assembling into a related E3 ligase complex. The intricate structure of GIDAnt enables anticipating and ultimately binding various N-degron-targeting (i.e., "N-end rule") substrate receptors, while the GIDSR4 E3 forms a clamp-like structure juxtaposing substrate lysines with the ubiquitylation active site. The data reveal evolutionarily conserved GID complexes as a family of multisubunit E3 ubiquitin ligases responsive to extracellular stimuli.

Rationale and design of GENEiUS: a prospective observational study on the genetic and environmental determinants of body mass index evolution in Canadian undergraduate students.

INTRODUCTION: Obesity is a global epidemic and is a risk factor for developing other comorbidities. Young adulthood is a critical period for body weight change and establishing healthy lifestyle behaviours. The 'Freshman 15' suggests that undergraduate students gain 15 lbs (6.8 kg) during their first year of university, although evidence estimates a more modest weight gain of approximately 3-5 lbs (1.4-2.3 kg). Previous studies have only investigated weight change in the first year and do not study potential risk factors. Genetic and EnviroNmental Effects on weight in University Students (GENEiUS) is a prospective observational study which will investigate the environmental and biological determinants of weight change in undergraduate students over 4 years. METHODS AND ANALYSIS: The GENEiUS study will recruit 2500 multiethnic undergraduates aged 17-25 years at McMaster University at the start of their first year and will follow them every 6 months for 4 years. Primary outcomes are obesity traits: body mass index, waist circumference, waist-to-hip ratio, body fat mass and body fat percentage. The contribution of well-established and novel genetic variants for obesity traits and heritability values will be derived from whole-genome single-nucleotide polymorphism genotyping arrays. Civil status, age, sex, ethnicity, length of residence in Canada, religiosity, energy intake, physical activity, exercise motivation, electronic screen time, sleep patterns, history of assault, smoking status, alcohol consumption, medication and drug use, stress, impulsivity, body image perception, self-esteem, anxiety, eating disorders and depression will be investigated for their effect on obesity traits. The findings of the GENEiUS study will be used to help design obesity prevention programme in North American universities with multiethnic populations. ETHICS AND DISSEMINATION: Ethical approval of the study protocol has been obtained from the Hamilton Integrated Research Ethics Board. Study results will be disseminated through scientific publications, scholarly meetings, and collaborative meetings with university administration and student groups.

Digesting cytotoxic stressors - an unconventional mechanism to induce autophagy.

Autophagy is an essential and fundamental pathway that clears unwanted or damaged material from the cell. Initiation of autophagy was previously shown to be dependent on the Ulk1/2 kinase complex. In this issue of The FEBS Journal, Braden and Neufeld investigated the Ulk3 homolog in Drosophila, and proposed a novel, Ulk1/2 independent pathway for autophagy initiation.

Distinct Prion Domain Sequences Ensure Efficient Amyloid Propagation by Promoting Chaperone Binding or Processing In Vivo.

Prions are a group of proteins that can adopt a spectrum of metastable conformations in vivo. These alternative states change protein function and are self-replicating and transmissible, creating protein-based elements of inheritance and infectivity. Prion conformational flexibility is encoded in the amino acid composition and sequence of the protein, which dictate its ability not only to form an ordered aggregate known as amyloid but also to maintain and transmit this structure in vivo. But, while we can effectively predict amyloid propensity in vitro, the mechanism by which sequence elements promote prion propagation in vivo remains unclear. In yeast, propagation of the [PSI+] prion, the amyloid form of the Sup35 protein, has been linked to an oligopeptide repeat region of the protein. Here, we demonstrate that this region is composed of separable functional elements, the repeats themselves and a repeat proximal region, which are both required for efficient prion propagation. Changes in the numbers of these elements do not alter the physical properties of Sup35 amyloid, but their presence promotes amyloid fragmentation, and therefore maintenance, by molecular chaperones. Rather than acting redundantly, our observations suggest that these sequence elements make complementary contributions to prion propagation, with the repeat proximal region promoting chaperone binding to and the repeats promoting chaperone processing of Sup35 amyloid.

Evaluating the transferability of 15 European-derived fasting plasma glucose SNPs in Mexican children and adolescents.

Genome wide association studies (GWAS) have identified single-nucleotide polymorphisms (SNPs) that are associated with fasting plasma glucose (FPG) in adult European populations. The contribution of these SNPs to FPG in non-Europeans and children is unclear. We studied the association of 15 GWAS SNPs and a genotype score (GS) with FPG and 7 metabolic traits in 1,421 Mexican children and adolescents from Mexico City. Genotyping of the 15 SNPs was performed using TaqMan Open Array. We used multivariate linear regression models adjusted for age, sex, body mass index standard deviation score, and recruitment center. We identified significant associations between 3 SNPs (G6PC2 (rs560887), GCKR (rs1260326), MTNR1B (rs10830963)), the GS and FPG level. The FPG risk alleles of 11 out of the 15 SNPs (73.3%) displayed significant or non-significant beta values for FPG directionally consistent with those reported in adult European GWAS. The risk allele frequencies for 11 of 15 (73.3%) SNPs differed significantly in Mexican children and adolescents compared to European adults from the 1000G Project, but no significant enrichment in FPG risk alleles was observed in the Mexican population. Our data support a partial transferability of European GWAS FPG association signals in children and adolescents from the admixed Mexican population.

Spatial quality control bypasses cell-based limitations on proteostasis to promote prion curing.

The proteostasis network has evolved to support protein folding under normal conditions and to expand this capacity in response to proteotoxic stresses. Nevertheless, many pathogenic states are associated with protein misfolding, revealing in vivo limitations on quality control mechanisms. One contributor to these limitations is the physical characteristics of misfolded proteins, as exemplified by amyloids, which are largely resistant to clearance. However, other limitations imposed by the cellular environment are poorly understood. To identify cell-based restrictions on proteostasis capacity, we determined the mechanism by which thermal stress cures the [PSI(+)]/Sup35 prion. Remarkably, Sup35 amyloid is disassembled at elevated temperatures by the molecular chaperone Hsp104. This process requires Hsp104 engagement with heat-induced non-prion aggregates in late cell-cycle stage cells, which promotes its asymmetric retention and thereby effective activity. Thus, cell division imposes a potent limitation on proteostasis capacity that can be bypassed by the spatial engagement of a quality control factor.

FMRP targets distinct mRNA sequence elements to regulate protein expression.

Fragile X syndrome (FXS) is a multi-organ disease that leads to mental retardation, macro-orchidism in males and premature ovarian insufficiency in female carriers. FXS is also a prominent monogenic disease associated with autism spectrum disorders (ASDs). FXS is typically caused by the loss of fragile X mental retardation 1 (FMR1) expression, which codes for the RNA-binding protein FMRP. Here we report the discovery of distinct RNA-recognition elements that correspond to the two independent RNA-binding domains of FMRP, in addition to the binding sites within the messenger RNA targets for wild-type and I304N mutant FMRP isoforms and the FMRP paralogues FXR1P and FXR2P (also known as FXR1 and FXR2). RNA-recognition-element frequency, ratio and distribution determine target mRNA association with FMRP. Among highly enriched targets, we identify many genes involved in ASD and show that FMRP affects their protein levels in human cell culture, mouse ovaries and human brain. Notably, we discovered that these targets are also dysregulated in Fmr1(-/-) mouse ovaries showing signs of premature follicular overdevelopment. These results indicate that FMRP targets share signalling pathways across different cellular contexts. As the importance of signalling pathways in both FXS and ASD is becoming increasingly apparent, our results provide a ranked list of genes as basis for the pursuit of new therapeutic targets for these neurological disorders.

P2Y2 receptor transcription is increased by NF-kappa B and stimulates cyclooxygenase-2 expression and PGE2 released by intestinal epithelial cells.

Inflammatory stresses associated with inflammatory bowel diseases up-regulate P2Y(2) mRNA receptor expression in the human colon adenocarcinoma cell line Caco-2, the noncancerous IEC-6 cells and in colonic tissues of patient suffering from Crohn's disease and ulcerative colitis. However, the transcriptional events regulating P2Y(2) receptor (P2Y(2)R) expression are not known. We have identified a putative transcription start site in the P2Y(2)R gene and demonstrated acetylation of Lys(14) on histone H3 and Lys(8) on histone H4, thus suggesting that the chromatin associated with the P2Y(2) promoter is accessible to transcription factors. We also showed that the transcription factor NF-kappaB p65 regulates P2Y(2)R transcription under both proinflammatory and basal conditions. A NF-kappaB-responsive element was identified at -181 to -172 bp in the promoter region of P2Y(2). Hence, activation of P2Y(2)R by ATP and UTP stimulated cyclooxygenase-2 expression and PGE(2) secretion by intestinal epithelial cells. These findings demonstrate that P2Y(2)R expression is regulated during intestinal inflammation through an NF-kappaB p65-dependent mechanism and could contribute not only to inflammatory bowel disease but also to other inflammatory diseases by regulating PG release.

Promoting MPhi transepithelial migration by stimulating the epithelial cell P2Y(2) receptor.

In intestine, neutrophils are recruited in response to bacterial infiltration and their anti-cellular activities contribute to inflammatory bowel diseases. In contrast, little is known regarding the recruitment of MPhi to the intestinal epithelium. Extracellular adenosine and uridine 5'-triphosphate (ATP and UTP) can function as leukocyte chemoattractants. We investigated the effects of these nucleotides on the ability of intestinal epithelial cells (IEC) to promote MPhi transepithelial migration and adhesion. ATP and UTP promoted the migration of neutrophil-like PLB-985 cells and MPhi across a Caco-2 monolayer. The MPhi-like U-937 cells adhered to nucleotide-stimulated IEC monolayers. In mice with intestinal inflammation, there were infiltrating CD68(+) MPhi in the colonic epithelium and CD68(+) MPhi present at the apical surface of colonocytes. We determined that ATP and UTP activated the P2Y(2) receptor P (P2Y(2)R) to increase ICAM-1 expression, which mediated the adhesion of MPhi to the apical surface of IEC. Intriguingly, stimulation of IEC with nucleotides did not increase the adhesion of neutrophils. However, in the presence of adherent MPhi, there was adhesion of neutrophils, suggesting that MPhi may serve as anchors for neutrophil adhesion. These studies provide insight into the inflammatory mechanisms that contribute to inflammatory bowel diseases and identify potential therapeutic targets for the treatment of gastrointestinal disorders.

Intestinal inflammation increases the expression of the P2Y6 receptor on epithelial cells and the release of CXC chemokine ligand 8 by UDP.

Epithelial cells participate in the immune response of the intestinal mucosa. Extracellular nucleotides have been recognized as inflammatory molecules. We investigated the role of extracellular nucleotides and their associated P2Y receptors in the secretion of cytokines by epithelial cells. The effect of intestinal inflammation on P2Y(6) receptor expression was determined by PCR in the mouse, rat, and human. Localization of the P2Y(6) receptor was determined by immunofluorescence microscopy in the colon of normal and dextran sulfate sodium-treated mice. The effect of P2Y(6) activation by UDP on cytokine expression and release by epithelial cells was determined using a combination of Western blots, luciferase assays, RT-PCR, cytokine Ab arrays, and ELISA. Inflammation up-regulates P2Y(2) as well as P2Y(6) receptor expression in the mucosa of the colon of colitic mice. In vitro, we demonstrated that UDP could be released by Caco-2/15 cells. We have confirmed the increased expression of P2Y(6) by challenging intestinal epithelial cell-6 and Caco-2/15 cells with TNF-alpha and IFN-gamma and showing that stimulation of epithelial cells by UDP results in an increased expression and release of CXCL8 by an ERK1/2-dependent mechanism. The increase in CXCL8 expression was associated with a transcriptional activation by the P2Y(6) receptor. This study is the first report demonstrating the implication of P2Y receptors in the inflammatory response of intestinal epithelial cells. We show for the first time that P2Y(6), as well as P2Y(2), expression is increased by the stress associated with intestinal inflammation. These results demonstrate the emergence of extracellular nucleotide signaling in the orchestration of intestinal inflammation.