Background Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists... more Background Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists may lead to opioid dependence. The analgesic and addictive properties of opioid agonist drugs are mediated primarily via the mu-opioid receptor (MOR). Opioid agonists appear to alter neuronal morphology in key brain regions implicated in the development of opioid dependence. However, the precise role of the MOR in the development of these neuronal alterations remains elusive. We hypothesize that identifying and characterizing novel MOR interacting proteins (MORIPs) may help to elucidate the underlying mechanisms involved in the development of opioid dependence. Results GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was identified as a MORIP in a modified split ubiquitin yeast two-hybrid screen. GPR177 is an evolutionarily conserved protein that plays a critical role in mediating Wnt protein secretion from Wnt producing cells. The MOR/GPR177 interaction was validated in pulldown, coimmunoprecipitation, and colocalization studies using mammalian tissue culture cells. The interaction was also observed in rodent brain, where MOR and GPR177 were coexpressed in close spatial proximity within striatal neurons. At the cellular level, morphine treatment caused a shift in the distribution of GPR177 from cytosol to the cell surface, leading to enhanced MOR/GPR177 complex formation at the cell periphery and the inhibition of Wnt protein secretion. Conclusions It is known that chronic morphine treatment decreases dendritic arborization and hippocampal neurogenesis, and Wnt proteins are essential for these processes. We therefore propose that the morphine-mediated MOR/GPR177 interaction may result in decreased Wnt secretion in the CNS, resulting in atrophy of dendritic arbors and decreased neurogenesis. Our results demonstrate a previously unrecognized role for GPR177 in regulating cellular response to opioid drugs.
Eukaryotic cells respond to growth, developmental and environmental cues in large part by regulat... more Eukaryotic cells respond to growth, developmental and environmental cues in large part by regulating the expression of specific sets of genes. Befitting the wide range of these signals and the proper gene regulatory response, mechanisms of transcriptional activation in eukaryotes are impressively diverse. These mechanisms are built on the modular design of cis-acting DNA regulatory sequences and of trans-acting regulatory proteins, coupled with flexibility and diversity in the protein:protein interactions linking activators to chromatin-modifying enzymes and general transcription factors. This review summarizes and illustrates these principles of modular design and combinatorial logic underlying transcriptional activation in eukaryotes.
Community-based research often brings investigators from different disciplinary backgrounds toget... more Community-based research often brings investigators from different disciplinary backgrounds together with community representatives to conduct research on topics of mutual concern. This paper describes a case example that illustrates an interdisciplinary/intersectoral study of depression and barriers to mental health care among older adults and illustrate the factors central to implementing a successful research partnership. It will address the following conditions that facilitate and challenge interdisciplinary/intersectoral research: (1) achieving commonality of purpose in study design and research and referral approaches; (2) ensuring the ability to develop, field-test and implement psychometrically rigorous and culturally and qualitatively appropriate instruments; (3) building effective management structures for interdisciplinary/intersectoral research partnerships; and (4) identifying, training and supporting qualified researchers to carry out a mental health study with older ethnically diverse adults. The paper concludes with strengths and limitations of the approach.
GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was recently identified as a n... more GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was recently identified as a novel mu-opioid receptor (MOR) interacting protein. GPR177 is a transmembrane protein pivotal to mediating the secretion of Wnt signaling proteins. Wnt proteins, in turn, are essential in regulating neuronal development, a phenomenon inhibited upon chronic exposure to MOR agonists such as morphine and heroin. We previously showed that GPR177 and MOR are co-localized in the mouse dorsolateral striatum; however, the nature of this interaction was not fully elucidated. Therefore, in the present study, we examined cellular substrates for interactions between GPR177 and MOR using a combined immunogold-silver and peroxidase detection approach in coronal sections in the dorsolateral segment of the striatum. Semi-quantitative analysis of the ultrastructural distribution of GPR177 and MOR in striatal somata and in dendritic processes showed that, of the somata and dendritic processes exhibiting GPR177, 32% contained MOR immunolabeling while for profiles exhibiting MOR, 37% also contained GPR177 immunoreactivity. GPR177-labeled particles were localized predominantly along both the plasma membrane and within the cytoplasm of MORlabeled dendrites. Somata and dendritic processes that contained both GPR177 and MOR more often received symmetric (inhibitory-type) synapses from unlabeled axon terminals. To further define the phenotype of GPR177 and MOR-containing cellular profiles, triple immunofluorescence detection showed that GPR177 and MOR are localized in neurons containing the opioid peptide, enkephalin, within the dorsolateral striatum. The results provide an anatomical substrate for interactions between MOR and its interacting protein, GPR177, in striatal opioid-containing neurons that may underlie the morphological alterations produced in neurons by chronic opiate use.
Background Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists... more Background Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists may lead to opioid dependence. The analgesic and addictive properties of opioid agonist drugs are mediated primarily via the mu-opioid receptor (MOR). Opioid agonists appear to alter neuronal morphology in key brain regions implicated in the development of opioid dependence. However, the precise role of the MOR in the development of these neuronal alterations remains elusive. We hypothesize that identifying and characterizing novel MOR interacting proteins (MORIPs) may help to elucidate the underlying mechanisms involved in the development of opioid dependence. Results GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was identified as a MORIP in a modified split ubiquitin yeast two-hybrid screen. GPR177 is an evolutionarily conserved protein that plays a critical role in mediating Wnt protein secretion from Wnt producing cells. The MOR/GPR177 interaction was validated in pulldown, coimmunoprecipitation, and colocalization studies using mammalian tissue culture cells. The interaction was also observed in rodent brain, where MOR and GPR177 were coexpressed in close spatial proximity within striatal neurons. At the cellular level, morphine treatment caused a shift in the distribution of GPR177 from cytosol to the cell surface, leading to enhanced MOR/GPR177 complex formation at the cell periphery and the inhibition of Wnt protein secretion. Conclusions It is known that chronic morphine treatment decreases dendritic arborization and hippocampal neurogenesis, and Wnt proteins are essential for these processes. We therefore propose that the morphine-mediated MOR/GPR177 interaction may result in decreased Wnt secretion in the CNS, resulting in atrophy of dendritic arbors and decreased neurogenesis. Our results demonstrate a previously unrecognized role for GPR177 in regulating cellular response to opioid drugs.
Eukaryotic cells respond to growth, developmental and environmental cues in large part by regulat... more Eukaryotic cells respond to growth, developmental and environmental cues in large part by regulating the expression of specific sets of genes. Befitting the wide range of these signals and the proper gene regulatory response, mechanisms of transcriptional activation in eukaryotes are impressively diverse. These mechanisms are built on the modular design of cis-acting DNA regulatory sequences and of trans-acting regulatory proteins, coupled with flexibility and diversity in the protein:protein interactions linking activators to chromatin-modifying enzymes and general transcription factors. This review summarizes and illustrates these principles of modular design and combinatorial logic underlying transcriptional activation in eukaryotes.
Community-based research often brings investigators from different disciplinary backgrounds toget... more Community-based research often brings investigators from different disciplinary backgrounds together with community representatives to conduct research on topics of mutual concern. This paper describes a case example that illustrates an interdisciplinary/intersectoral study of depression and barriers to mental health care among older adults and illustrate the factors central to implementing a successful research partnership. It will address the following conditions that facilitate and challenge interdisciplinary/intersectoral research: (1) achieving commonality of purpose in study design and research and referral approaches; (2) ensuring the ability to develop, field-test and implement psychometrically rigorous and culturally and qualitatively appropriate instruments; (3) building effective management structures for interdisciplinary/intersectoral research partnerships; and (4) identifying, training and supporting qualified researchers to carry out a mental health study with older ethnically diverse adults. The paper concludes with strengths and limitations of the approach.
GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was recently identified as a n... more GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was recently identified as a novel mu-opioid receptor (MOR) interacting protein. GPR177 is a transmembrane protein pivotal to mediating the secretion of Wnt signaling proteins. Wnt proteins, in turn, are essential in regulating neuronal development, a phenomenon inhibited upon chronic exposure to MOR agonists such as morphine and heroin. We previously showed that GPR177 and MOR are co-localized in the mouse dorsolateral striatum; however, the nature of this interaction was not fully elucidated. Therefore, in the present study, we examined cellular substrates for interactions between GPR177 and MOR using a combined immunogold-silver and peroxidase detection approach in coronal sections in the dorsolateral segment of the striatum. Semi-quantitative analysis of the ultrastructural distribution of GPR177 and MOR in striatal somata and in dendritic processes showed that, of the somata and dendritic processes exhibiting GPR177, 32% contained MOR immunolabeling while for profiles exhibiting MOR, 37% also contained GPR177 immunoreactivity. GPR177-labeled particles were localized predominantly along both the plasma membrane and within the cytoplasm of MORlabeled dendrites. Somata and dendritic processes that contained both GPR177 and MOR more often received symmetric (inhibitory-type) synapses from unlabeled axon terminals. To further define the phenotype of GPR177 and MOR-containing cellular profiles, triple immunofluorescence detection showed that GPR177 and MOR are localized in neurons containing the opioid peptide, enkephalin, within the dorsolateral striatum. The results provide an anatomical substrate for interactions between MOR and its interacting protein, GPR177, in striatal opioid-containing neurons that may underlie the morphological alterations produced in neurons by chronic opiate use.
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Papers by Evi Reyes