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PURPOSE: Dominant variants in the retinoic acid receptor beta (RARB) gene underlie a syndromic form of microphthalmia, known as MCOPS12, which is associated with other birth anomalies and global developmental delay with spasticity and/or dystonia. Here, we report 25 affected individuals with 17 novel pathogenic or likely pathogenic variants in RARB. This study aims to characterize the functional impact of these variants and describe the clinical spectrum of MCOPS12. METHODS: We used in vitro transcriptional assays and in silico structural analysis to assess the functional relevance of RARB variants in affecting the normal response to retinoids. RESULTS: We found that all RARB variants tested in our assays exhibited either a gain-of-function or a loss-of-function activity. Loss-of-function variants disrupted RARB function through a dominant-negative effect, possibly by disrupting ligand binding and/or coactivators' recruitment. By reviewing clinical data from 52 affected individuals, we found that disruption of RARB is associated with a more variable phenotype than initially suspected, with the absence in some individuals of cardinal features of MCOPS12, such as developmental eye anomaly or motor impairment. CONCLUSION: Our study indicates that pathogenic variants in RARB are functionally heterogeneous and associated with extensive clinical heterogeneity.
Assuntos
Microftalmia , Receptores do Ácido Retinoico , Humanos , Receptores do Ácido Retinoico/genética , Receptores do Ácido Retinoico/metabolismo , RetinoidesRESUMO
Miller et al. (2010) previously suggested that borderline pathology, vulnerable narcissism, and Factor 2 psychopathy share a common "Vulnerable Dark Triad" (VDT) core. The present study (N = 1,023 community participants) aims to test that hypothesis using exploratory and confirmatory bifactor analyses. We found support for a bifactor model that obtained satisfactory fits and other adequate validity indices, which included a general VDT factor and three group factors (Reckless, Entitled, Hiding). The general VDT factor was mostly saturated with borderline symptoms items reflecting self-hatred and worthlessness, which did not form a group factor; these results add to previous research suggesting that features of borderline pathology may represent the core of personality pathology. The three group factors had distinctive relationships with Dark Triad traits, pathological trait domains, and aggression. In contrast with the three group factors, the general VDT factor more strongly incremented the prediction of negative affectivity and hostility; the group factors more strongly incremented the prediction of grandiosity, egocentrism, callousness, Machiavellianism, and direct (physical/verbal) aggression. Alignment of the retained bifactor model with influent models of personality pathology and conceptual/methodological implications of the present results for research on the hypothesized VDT are discussed, as well as some clinical implications of the findings.
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Maquiavelismo , Personalidade , Humanos , Transtorno da Personalidade Antissocial , Narcisismo , AgressãoRESUMO
Neuron-derived orphan receptor 1, NR4A3 (Nor1)/NR4A3 is an orphan nuclear receptor involved in the transcriptional control of developmental and neurological functions. Oxidative stress-induced conditions are primarily associated with neurological defects in humans, yet the impact on Nor1-mediated transcription of neuronal genes remains with unknown mechanism. Here, we demonstrate that Nor1 is a non-conventional target of SUMO2/3 conjugation at Lys-137 contained in an atypic ψKxSP motif referred to as the pSuM. Nor1 pSuM SUMOylation differs from the canonical process with the obligate phosphorylation of Ser-139 by Ras signaling to create the required negatively charged interface for SUMOylation. Additional phosphorylation at sites flanking the pSuM is also mediated by the coordinated action of protein kinase casein kinase 2 to function as a small ubiquitin-like modifier enhancer, regulating Nor1-mediated transcription and proteasomal degradation. Nor1 responsive genes involved in cell proliferation and metabolism, such as activating transcription factor 3, cyclin D1, CASP8 and FADD-like apoptosis regulator, and enolase 3 were upregulated in response to pSuM disruption in mouse HT-22 hippocampal neuronal cells and human neuroblastoma SH-SY5Y cells. We also identified critical antioxidant genes, such as catalase, superoxide dismutase 1, and microsomal glutathione S-transferase 2, as responsive targets of Nor1 under pSuM regulation. Nor1 SUMOylation impaired gene transcription through less effective Nor1 chromatin binding and reduced enrichment of histone H3K27ac marks to gene promoters. These effects resulted in decreased neuronal cell growth, increased apoptosis, and reduced survival to oxidative stress damage, underlying the role of pSuM-modified Nor1 in redox homeostasis. Our findings uncover a hierarchical post-translational mechanism that dictates Nor1 non-canonical SUMOylation, disrupting Nor1 transcriptional competence, and neuroprotective redox sensitivity.
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Sobrevivência Celular/genética , Proteínas de Ligação a DNA/genética , Receptores de Esteroides/genética , Receptores dos Hormônios Tireóideos/genética , Sumoilação/genética , Animais , Apoptose/genética , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/genética , Quinase do Ponto de Checagem 2/genética , Regulação da Expressão Gênica/genética , Células HEK293 , Hipocampo/metabolismo , Homeostase/genética , Humanos , Camundongos , Neuroblastoma/genética , Neurônios/metabolismo , Oxirredução , Estresse Oxidativo/genética , Fosforilação/genética , Regiões Promotoras Genéticas/genética , Processamento de Proteína Pós-Traducional/genética , Transcrição Gênica/genética , Ativação Transcricional/genética , Regulação para Cima/genéticaRESUMO
Uncovering the biological role of nuclear receptor peroxisome proliferator-activated receptors (PPARs) has greatly advanced our knowledge of the transcriptional control of glucose and energy metabolism. As such, pharmacological activation of PPARγ has emerged as an efficient approach for treating metabolic disorders with the current use of thiazolidinediones to improve insulin resistance in diabetic patients. The recent identification of growth hormone releasing peptides (GHRP) as potent inducers of PPARγ through activation of the scavenger receptor CD36 has defined a novel alternative to regulate essential aspects of lipid and energy metabolism. Recent advances on the emerging role of CD36 and GHRP hexarelin in regulating PPARγ downstream actions with benefits on atherosclerosis, hepatic cholesterol biosynthesis and fat mitochondrial biogenesis are summarized here. The response of PPARγ coactivator PGC-1 is also discussed in these effects. The identification of the GHRP-CD36-PPARγ pathway in controlling various tissue metabolic functions provides an interesting option for metabolic disorders.
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Antígenos CD36/metabolismo , Doenças Metabólicas/metabolismo , PPAR gama/metabolismo , Transdução de Sinais , Animais , Antígenos CD36/agonistas , Descoberta de Drogas , Metabolismo Energético/efeitos dos fármacos , Ácidos Graxos/metabolismo , Humanos , Resistência à Insulina , Doenças Metabólicas/tratamento farmacológico , Doenças Metabólicas/patologia , Oligopeptídeos/farmacologia , Oligopeptídeos/uso terapêutico , PPAR gama/agonistas , Transdução de Sinais/efeitos dos fármacosRESUMO
Retinoic acid (RA) signaling plays a key role in the development and function of several systems in mammals. We previously discovered that the de novo mutations c.1159C>T (p.Arg387Cys) and c.1159C>A (p.Arg387Ser) in the RA Receptor Beta (RARB) gene cause microphthalmia and diaphragmatic hernia. However, the natural history of affected subjects beyond the prenatal or neonatal period was unknown. Here, we describe nine additional subjects with microphthalmia who have de novo mutations in RARB, including the previously described p.Arg387Cys as well as the novel c.887G>C (p.Gly296Ala) and c.638T>C (p.Leu213Pro). Moreover, we review the information on four previously reported cases. All subjects who survived the neonatal period (n = 10) displayed severe global developmental delay with progressive motor impairment due to spasticity and/or dystonia (with or without chorea). The majority of subjects also showed Chiari type I malformation and severe feeding difficulties. We previously found that p.Arg387Cys and p.Arg387Ser induce a gain-of-function. We show here that the p.Gly296Ala and p.Leu213Pro RARB mutations further promote the RA ligand-induced transcriptional activity by twofold to threefold over the wild-type receptor, also indicating a gain-of-function mechanism. These observations suggest that precise regulation of RA signaling is required for brain development and/or function in humans.
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Mutação com Ganho de Função , Deficiência Intelectual/genética , Transtornos dos Movimentos/genética , Receptores do Ácido Retinoico/genética , Adolescente , Criança , Pré-Escolar , Distúrbios Distônicos , Feminino , Humanos , Recém-Nascido , Masculino , Modelos Moleculares , Mutação de Sentido Incorreto , Conformação Proteica , Receptores do Ácido Retinoico/química , Ativação TranscricionalRESUMO
Anophthalmia and/or microphthalmia, pulmonary hypoplasia, diaphragmatic hernia, and cardiac defects are the main features of PDAC syndrome. Recessive mutations in STRA6, encoding a membrane receptor for the retinol-binding protein, have been identified in some cases with PDAC syndrome, although many cases have remained unexplained. Using whole-exome sequencing, we found that two PDAC-syndrome-affected siblings, but not their unaffected sibling, were compound heterozygous for nonsense (c.355C>T [p.Arg119(∗)]) and frameshift (c.1201_1202insCT [p.Ile403Serfs(∗)15]) mutations in retinoic acid receptor beta (RARB). Transfection studies showed that p.Arg119(∗) and p.Ile403Serfs(∗)15 altered RARB had no transcriptional activity in response to ligands, confirming that the mutations induced a loss of function. We then sequenced RARB in 15 subjects with anophthalmia and/or microphthalmia and at least one other feature of PDAC syndrome. Surprisingly, three unrelated subjects with microphthalmia and diaphragmatic hernia showed de novo missense mutations affecting the same codon; two of the subjects had the c.1159C>T (Arg387Cys) mutation, whereas the other one carried the c.1159C>A (p.Arg387Ser) mutation. We found that compared to the wild-type receptor, p.Arg387Ser and p.Arg387Cys altered RARB induced a 2- to 3-fold increase in transcriptional activity in response to retinoic acid ligands, suggesting a gain-of-function mechanism. Our study thus suggests that both recessive and dominant mutations in RARB cause anophthalmia and/or microphthalmia and diaphragmatic hernia, providing further evidence of the crucial role of the retinoic acid pathway during eye development and organogenesis.
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Hérnia Diafragmática/genética , Microftalmia/genética , Mutação , Receptores do Ácido Retinoico/genética , Adolescente , Anoftalmia/genética , Anoftalmia/metabolismo , Exoma , Feminino , Hérnia Diafragmática/metabolismo , Humanos , Recém-Nascido , Masculino , Microftalmia/metabolismo , Receptores do Ácido Retinoico/metabolismo , Proteínas de Ligação ao Retinol/genética , Proteínas de Ligação ao Retinol/metabolismo , Tretinoína/metabolismoRESUMO
The scavenger receptor CD36 plays a central role in lipid metabolism by promoting macrophage cholesterol efflux with the potential to reduce atherosclerotic lesions. However, the effect of CD36 on de novo cholesterol synthesis is not known. Here, we describe the cellular mechanism by which CD36 activation induces cholesterol depletion in HepG2 cells. Using the CD36 ligand hexarelin, we found a rapid phosphorylation of HMG-CoA reductase Ser-872 in treated cells, resulting in inactivation of the rate-limiting enzyme in sterol synthesis. Degradation of HMG-CoA reductase by the ubiquitin-proteasome pathway was also enhanced by hexarelin, through an increased recruitment of the anchor proteins insulin-induced gene (Insig)-1 and Insig-2. Genes encoding key enzymes involved in cholesterol synthesis and under the control of transcription factor sterol regulatory element-binding protein (SREBP)-2 remained unresponsive to sterol depletion, due to retention of the SREBP-2 escort protein Scap by Insig-1/2. Insig1 and Insig2 gene expression was also increased through activation of nuclear receptor peroxisome-proliferator activating receptor γ (PPARγ) by CD36, which lifted the inhibitory effect of PPARγ1 Ser-84 phosphorylation. Recruitment of coactivator peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α) to activated AMPKα was also promoted, resulting in PGC-1α transcriptional activation through Sirt1-mediated deacetylation, increased recruitment of PPARγ, and up-regulation of Insig-1/2, revealing a regulatory role of CD36 on PGC-1α signaling. Our data identify CD36 as a novel regulator of HMG-CoA reductase function and Insig-1/2 expression, 2 critical steps regulating cholesterol synthesis in hepatocytes.
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Antígenos CD36/metabolismo , Colesterol/biossíntese , Hepatócitos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , PPAR gama/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Western Blotting , Antígenos CD36/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células HEK293 , Células Hep G2 , Hepatócitos/patologia , Humanos , Hidroximetilglutaril-CoA Redutases/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Oligopeptídeos/farmacologia , PPAR gama/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fosforilação/efeitos dos fármacos , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Serina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Proteína de Ligação a Elemento Regulador de Esterol 2/genética , Proteína de Ligação a Elemento Regulador de Esterol 2/metabolismo , Fatores de Transcrição/genéticaRESUMO
BACKGROUND: Nor1/NR4A3 is a member of the NR4A subfamily of nuclear receptors that play essential roles in regulating gene expression related to development, cell homeostasis and neurological functions. However, Nor1 is still considered an orphan receptor, as its natural ligand remains unclear for mediating transcriptional activation. Yet other activation signals may modulate Nor1 activity, although their precise role in the development and maintenance of the nervous system remains elusive. METHODS: We used transcriptional reporter assays, gene expression profiling, protein turnover measurement, and cell growth assays to assess the functional relevance of Nor1 and SUMO-defective variants in neuronal cells. SUMO1 and SUMO2 conjugation to Nor1 were assessed by immunoprecipitation. Tubulin stability was determined by acetylation and polymerization assays, and live-cell fluorescent microscopy. RESULTS: Here, we demonstrate that Nor1 undergoes SUMO1 conjugation at Lys-89 within a canonical ψKxE SUMOylation motif, contributing to the complex pattern of Nor1 SUMOylation, which also includes Lys-137. Disruption of Lys-89, thereby preventing SUMO1 conjugation, led to reduced Nor1 transcriptional competence and protein stability, as well as the downregulation of genes involved in cell growth and metabolism, such as ENO3, EN1, and CFLAR, and in microtubule cytoskeleton dynamics, including MAP2 and MAPT, which resulted in reduced survival of neuronal cells. Interestingly, Lys-89 SUMOylation was potentiated in response to nocodazole, a microtubule depolymerizing drug, although this was insufficient to rescue cells from microtubule disruption despite enhanced Nor1 gene expression. Instead, Lys-89 deSUMOylation reduced the expression of microtubule-severing genes like KATNA1, SPAST, and FIGN, and enhanced α-tubulin cellular levels, acetylation, and microfilament organization, promoting microtubule stability and resistance to nocodazole. These effects contrasted with Lys-137 SUMOylation, suggesting distinct regulatory mechanisms based on specific Nor1 input SUMOylation signals. CONCLUSIONS: Our study provides novel insights into Nor1 transcriptional signaling competence and identifies a hierarchical mechanism whereby selective Nor1 SUMOylation may govern neuronal cytoskeleton network dynamics and resistance against microtubule disturbances, a condition strongly associated with neurodegenerative diseases.
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Vachon and Lynam (2016) recently introduced a new measure of empathy, the Affective and Cognitive Measure of Empathy (ACME). Besides assessing the traditional dimensions of cognitive and affective empathy, the ACME includes an affective dissonance scale that covers "antiempathy," an important feature of the construct with prominent predictive value not included in other empathy measures. The aim of this study is to provide data on the French version of the ACME. A sample of 851 community-dwelling participants (59.4% female) completed online the ACME questionnaire along with other measures of empathy, dark and pathological personality traits, and aggression. The original ACME bifactor exploratory structural equation modeling structure (i.e., the three empathy dimensions of Cognitive, Affective Resonance, and Affective Dissonance with positive and negative wording items as method bifactors) was successfully reproduced with the French version. Furthermore, these scales displayed satisfying internal consistency coefficients, as well as good item properties according to Classical Test Theory. Convergent validity indices were also similar to those reported for the original English version, and scale scores reached full invariance across gender and proved to be partially invariant across language when comparing the present data to those from the original validation study. The French version of the ACME is well aligned with the original English version and offers a valuable alternative to French researchers and clinicians interested in measuring the various dimensions of empathy. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
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Empatia , Idioma , Cognição , Feminino , Humanos , Masculino , Transtornos da Personalidade/psicologia , Psicometria , Reprodutibilidade dos Testes , Inquéritos e QuestionáriosRESUMO
CONTEXT: Intrauterine growth restriction (IUGR) is an immediate outcome of an adverse womb environment, exposing newborns to developing cardiometabolic disorders later in life. OBJECTIVE: This study investigates the cardiac metabolic consequences and underlying mechanism of energy expenditure in developing fetuses under conditions of IUGR. METHODS: Using an animal model of IUGR characterized by uteroplacental vascular insufficiency, mitochondrial function, gene profiling, lipidomic analysis, and transcriptional assay were determined in fetal cardiac tissue and cardiomyocytes. RESULTS: IUGR fetuses exhibited an upregulation of key genes associated with fatty acid breakdown and ß-oxidation (Acadvl, Acadl, Acaa2), and mitochondrial carnitine shuttle (Cpt1a, Cpt2), instigating a metabolic gene reprogramming in the heart. Induction of Ech1, Acox1, Acox3, Acsl1, and Pex11a indicated a coordinated interplay with peroxisomal ß-oxidation and biogenesis mainly observed in females, suggesting sexual dimorphism in peroxisomal activation. Concurring with the sex-related changes, mitochondrial respiration rates were stronger in IUGR female fetal cardiomyocytes, accounting for enhanced adenosine 5'-triphosphate production. Mitochondrial biogenesis was induced in fetal hearts with elevated expression of Ppargc1a transcript specifically in IUGR females. Lipidomic analysis identified the accumulation of arachidonic, eicosapentaenoic, and docosapentaenoic polyunsaturated long-chain fatty acids (LCFAs) in IUGR fetal hearts, which leads to nuclear receptor peroxisome proliferator-activated receptor α (PPARα) transcriptional activation in cardiomyocytes. Also, the enrichment of H3K27ac chromatin marks to PPARα-responsive metabolic genes in IUGR fetal hearts outlines an epigenetic control in the early metabolic energy switch. CONCLUSION: This study describes a premature and sex-related remodeling of cardiac metabolism in response to an unfavorable intrauterine environment, with specific LCFAs that may serve as predictive effectors leading to IUGR.
Assuntos
Metabolismo Energético , Ácidos Graxos/metabolismo , Retardo do Crescimento Fetal/patologia , Coração Fetal/patologia , Mitocôndrias/patologia , Miócitos Cardíacos/patologia , Animais , Animais Recém-Nascidos , Feminino , Retardo do Crescimento Fetal/metabolismo , Coração Fetal/metabolismo , Masculino , Mitocôndrias/metabolismo , Miócitos Cardíacos/metabolismo , Oxirredução , Ratos Sprague-Dawley , Fatores SexuaisRESUMO
The goal of this study (N = 432 participants from a community sample) is to report on the psychometric properties of a French adaptation of the Expanded Version of the Three-Factor Levenson Self-Report Psychopathy Scale (E-LSRP), which was developed to alleviate some shortcomings of the original LSRP. A three correlated factor exploratory structural equation modeling model showed the best fits and attained satisfactory indices. There were significant, conceptually meaningful associations with measures of Dark Triad traits, pathological narcissism, empathy, impulsivity, substance misuse, and social desirability. Incremental validity over a 19-item scale proposed by Brinkley et al. was also mostly demonstrated, especially for convergent validity. Overall, the French E-LSRP possesses sound psychometric properties, comparable for the most part with the original instrument, and should be seen as a useful measure of psychopathic traits in community samples.
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Transtorno da Personalidade Antissocial , Desejabilidade Social , Transtorno da Personalidade Antissocial/diagnóstico , Humanos , Psicometria , Reprodutibilidade dos Testes , AutorrelatoRESUMO
There is evidence of a detrimental effect of emotion on reasoning. Recent studies suggest that this relationship is mediated by working memory, a function closely associated with the dorsolateral prefrontal cortex (dlPFC). Relying on transcranial direct current stimulation (tDCS), the present research explores the possibility that anodal stimulation of the dlPFC has the potential to prevent the effect of emotion on analytical reasoning. Thirty-four participants took part in a lab experiment and were tested twice: one session using offline anodal stimulation (with a 2 mA current stimulation applied to the left dlPFC for 20 min), one session using a control (sham) stimulation. In each session, participants solved syllogistic reasoning problems featuring neutral and emotionally negative contents. Results showed that anodal stimulation diminished the deleterious effect of emotion on syllogistic reasoning, but only for a subclass of problems: problems where the conclusion was logically valid. We discuss our results in the light of the reasoning literature as well as the apparent variability of tDCS effects.
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Farnesoid X receptor (FXR) is a ligand-activated nuclear receptor that plays a central role in regulating genes involved in bile acid homeostasis, and fat and glucose metabolism. Here, we demonstrate a post-translational interplay between FXR phosphorylation, SUMOylation, and ubiquitination that directs the receptor into an activation-degradation pathway in hepatocytes. We identify a non-canonical SUMOylation motif termed pSuM that conjugates SUMO2 at Lys-325 of FXR under the direct control of casein kinase 2 (CK2), which provides the required negative charge for Ubc9 and PIAS1 to perform SUMOylation, by phosphorylating Ser-327. Lys-325 SUMOylation is indispensable to the promotion of efficient ligand activation and transcriptional coactivation of FXR. Constitutive pSuM activation using a phospho-mimic Ser-327 mutant or catalytic CK2 expression strongly induces SUMO2 conjugation, which directs FXR ubiquitination and proteasome-dependent degradation. We also determine that such SUMOylation-dependent ubiquitination of FXR is mediated by the E3 ubiquitin ligase RNF4, which is required to achieve maximal induction of FXR and optimal up- or downregulation of responsive genes involved in bile acid homeostasis and liver regeneration. Our findings identify a highly regulated atypical SUMO conjugation motif that serves to coordinate FXR transcriptional competence, thereby expanding the intricate dynamics of the SUMOylation process used by incoming signals to govern metabolic gene regulation.
Assuntos
Caseína Quinase II/metabolismo , Proteínas Nucleares/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/metabolismo , Motivos de Aminoácidos , Células HEK293 , Hepatócitos/metabolismo , Humanos , Lisina/metabolismo , Mutação , Fosforilação , Processamento de Proteína Pós-Traducional , Proteólise , Proteínas de Ligação a RNA/genética , Serina/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/genética , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Sumoilação , UbiquitinaçãoRESUMO
SUMO conjugation has emerged as a dynamic process in regulating protein function. Here we identify estrogen receptor ß (ERß) to be a new target of SUMO-1. ERß SUMO-1 modification occurs on a unique nonconsensus sumoylation motif which becomes fully competent upon phosphorylation of its contained serine residue, which provides the essential negative charge for sumoylation. This process is further regulated by phosphorylation of additional adjacent serine residues by glycogen synthase kinase 3ß (GSK3ß), which maximizes ERß sumoylation in response to hormone. SUMO-1 attachment prevents ERß degradation by competing with ubiquitin at the same acceptor site and dictates ERß transcriptional inhibition by altering estrogen-responsive target promoter occupancy and gene expression in breast cancer cells. These findings uncovered a novel phosphorylated sumoylation motif (pSuM), which consists of the sequence ψKXS (where ψ represents a large hydrophobic residue) and which is connected to a GSK3-activated extension that functions as a SUMO enhancer. This extended pSuM offers a valuable signature to predict SUMO substrates under protein kinase regulation.
Assuntos
Receptor beta de Estrogênio/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Proteína SUMO-1/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Receptor beta de Estrogênio/química , Receptor beta de Estrogênio/genética , Glicogênio Sintase Quinase 3 beta , Células HEK293 , Humanos , Camundongos , Modelos Biológicos , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Fosforilação , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Transdução de Sinais , SumoilaçãoRESUMO
The peroxisome proliferator-activator receptor PPARgamma plays an essential role in vascular biology, modulating macrophage function and atherosclerosis progression. Recently, we have described the beneficial effect of combined activation of the ghrelin/GHS-R1a receptor and the scavenger receptor CD36 to induce macrophage cholesterol release through transcriptional activation of PPARgamma. Although the interplay between CD36 and PPARgamma in atherogenesis is well recognized, the contribution of the ghrelin receptor to regulate PPARgamma remains unknown. Here, we demonstrate that ghrelin triggers PPARgamma activation through a concerted signaling cascade involving Erk1/2 and Akt kinases, resulting in enhanced expression of downstream effectors LXRalpha and ABC sterol transporters in human macrophages. These effects were associated with enhanced PPARgamma phosphorylation independently of the inhibitory conserved serine-84. Src tyrosine kinase Fyn was identified as being recruited to GHS-R1a in response to ghrelin, but failure of activated Fyn to enhance PPARgamma Ser-84 specific phosphorylation relied on the concomitant recruitment of docking protein Dok-1, which prevented optimal activation of the Erk1/2 pathway. Also, substitution of Ser-84 preserved the ghrelin-induced PPARgamma activity and responsiveness to Src inhibition, supporting a mechanism independent of Ser-84 in PPARgamma response to ghrelin. Consistent with this, we found that ghrelin promoted the PI3-K/Akt pathway in a Galphaq-dependent manner, resulting in Akt recruitment to PPARgamma, enhanced PPARgamma phosphorylation and activation independently of Ser-84, and increased expression of LXRalpha and ABCA1/G1. Collectively, these results illustrate a complex interplay involving Fyn/Dok-1/Erk and Galphaq/PI3-K/Akt pathways to transduce in a concerted manner responsiveness of PPARgamma to ghrelin in macrophages.