Knockdown of GPRC5B alleviates the high glucose-induced inflammation and extracellular matrix deposition of podocyte through inhibiting NF-kB pathway

Background Diabetes is a serious disease that could greatly increase the risk of cardiovascular complications, whereas the underlying pathology of DN is still unknown. GPRC5B is a member of the RAIG subfamily of type 3 (family C) GPCR, and its role in DN is still unclear.Objective To unveil the role of GPRC5B in diabetic nephropathy (DN) progression and investigate the potential signaling pathway.Materials and methods Podocytes were stimulated with high glucose and expression of GPRC5B was analyzed by qPCR and western blot. Then the level of GPRC5B was depleted by siRNA transfection and inflammatory cytokine level was monitored by ELISA assay. The ECM depostion and the activation of NF-κB pathway were detected by Immunoblot.Results We investigated the possible role of GPRC5B in the pathology of diabetic nephropathy. We found GPRC5B was highly expressed in high glocuse (HG) induced podocytes. The depletion of GPRC5B inhibited HG induced cell inflammation. In addition, the ablation of GPRC5B suppressed the HG induced ECM deposition. We further found GPRC5B could alleviate the inflammation and extracellular matrix deposition of HG-induced podocytes through NF-κB pathway (AU)

Protective effects of a modified apelin-12 and dinitrosyl iron complexes in experimental cardioplegic ischemia and reperfusion

The maintenance of nitric oxide (NO) bioavailability has been recognized as an important component of myocardial protection during cardiac surgery. This study was designed to evaluate the efficacy of using two NO-donating compounds in cardioplegia and reperfusion: (III) a modified peptide apelin-12 (MA12) that activates endothelial NO synthase (eNOS) and (II) dinitrosyl iron complexes with reduced glutathione (DNIC-GS), a natural NO vehicle. Isolated perfused working rat hearts were subjected to normothermic global ischemia and reperfusion. St. Thomas' Hospital cardioplegic solution (STH) containing 140 μM MA12 or 100 μM DNIC-GS was used. In separate series, 140 μM MA12 or 100 μM DNIC-GS was administered at early reperfusion. Metabolic state of the hearts was evaluated by myocardial content of high-energy phosphates and lactate. Lactate dehydrogenase (LDH) activity in myocardial effluent was used as an index of cell membrane damage. Cardioplegia with MA12 or DNIC-GS improved recovery of coronary flow and cardiac function, and reduced LDH leakage in perfusate compared with STH without additives. Cardioplegic arrest with MA12 significantly enhanced preservation of high-energy phosphates and decreased accumulation of lactate in reperfused hearts. The overall protective effect of cardioplegia with MA12 was significantly greater than with DNIC-GS. The administration of MA12 or DNIC-GS at early reperfusion also increased metabolic and functional recovery of reperfused hearts. In this case, recovery of cardiac contractile and pump function indices was significantly higher if reperfusion was performed with DNIC-GS. The results show that MA12 and DNIC-GS are promising adjunct agents for protection of the heart during cardioplegic arrest and reperfusion

Loss of the nutrient sensor TAS1R3 leads to reduced bone resorption

The taste receptor type 1 (TAS1R) family of heterotrimeric G protein-coupled receptors participates in monitoring energy and nutrient status. TAS1R member 3 (TAS1R3) is a bi-functional protein that recognizes amino acids such as L-glycine and L-glutamate or sweet molecules such as sucrose and fructose when dimerized with TAS1R member 1 (TAS1R1) or TAS1R member 2 (TAS1R2), respectively. It was recently reported that deletion of TAS1R3 expression in Tas1R3 mutant mice leads to increased cortical bone mass but the underlying cellular mechanism leading to this phenotype remains unclear. Here, we independently corroborate the increased thickness of cortical bone in femurs of 20-week-old male Tas1R3 mutant mice and confirm that Tas1R3 is expressed in the bone environment. Tas1R3 is expressed in undifferentiated bone marrow stromal cells (BMSCs) in vitro and its expression is maintained during BMP2-induced osteogenic differentiation. However, levels of the bone formation marker procollagen type I N-terminal propeptide (PINP) are unchanged in the serum of 20-week-old Tas1R3 mutant mice as compared to controls. In contrast, levels of the bone resorption marker collagen type I C-telopeptide are reduced greater than 60% in Tas1R3 mutant mice. Consistent with this, Tas1R3 and its putative signaling partner Tas1R2 are expressed in primary osteoclasts and their expression levels positively correlate with differentiation status. Collectively, these findings suggest that high bone mass in Tas1R3 mutant mice is due to uncoupled bone remodeling with reduced osteoclast function and provide rationale for future experiments examining the cell-type-dependent role for TAS1R family members in nutrient sensing in postnatal bone remodeling

A common effect of angiotensin II and relaxin 2 on the PNT1A normal prostate epithelial cell line

The prostate gland is a part of the male reproductive tract which produces both angiotensin II (Ang II) and relaxin 2 (RLN2). The present study analyzes the effect of both these peptide hormones at concentration 10−8M on viability, proliferation, adhesion, migration, and invasion of normal prostate epithelial cells (PNT1A). Improved survival in two- and three-dimensional cell cultures was noted as well as visual changes in colony size and structure in Geltrex™. Stimulatory influence on cell viability of each peptide applied single was lower than in combination. Enhanced survival of PNT1A cells appears to be associated with increased BCL2/BAX messenger RNA (mRNA) expression ratio. Modulation of cell spreading and cell-extracellular matrix adhesion dynamics were also altered as an influence of tested hormone application. However, long-term Ang II and RLN2 effects may lead to an increase of normal prostate cell migration and invasion abilities. Moreover, gelatin zymography revealed that both gelatinases A and B were augmented by Ang II treatment, whereas RLN2 significantly stimulated only MMP-9 secretion. These results support the hypothesis that deregulation of locally secreted peptide hormones such as Ang II and RLN2 may take part in the development of certain cancers, including prostate cancer. Moreover, the observed ability of relaxin 2 to act as a regulator of mRNA expression levels not only LGR7 but also classic angiotensin receptors suggested that renin-angiotensin system and relaxin family peptide system are functionally linked (AU)

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Investigation of changes in apelin receptor mRNA and protein expression in the myocardium and aorta of rats with two-kidney, one-clip (2K1C) Goldblatt hypertension

Experimental and clinical evidences suggest that apelin and its receptor APJ are involved in the pathogenesis of cardiovascular complications. However, the role of apelin/APJ in hypertension is not sufficiently understood. Because chronic kidney diseases lead to hypertension and cardiac failure, we investigated the changes in apelin receptor gene expression in the myocardium and aorta of rat models of kidney disease hypertension. Two-kidney, one-clip (2K1C) hypertension was produced by placing a clip around the renal artery. Four and 16 weeks later, blood pressure, left ventricular end-diastolic pressure (LVEDP), serum apelin, and angiotensin II were measured. The messenger RNA (mRNA) and protein of APJ were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. Chronic hypertensive rats had approximately 10 times higher LVEDP (P < 0.001). 2K1C decreased serum apelin from 220 ± 11 to 170 ± 10 pg/mL in 16 weeks (P < 0.05). The mRNA expression of APJ significantly decreased in the heart and aorta at 4 weeks. At 16 weeks, the reduction was not significant in the heart but was significant in the aorta. At 4 weeks, the expression of the APJ protein significantly decreased in the heart but not in the aorta. At 16 weeks, APJ protein was significantly decreased only in the aorta. Reduction of serum apelin and downregulation of apelin receptors in both the heart and aorta may play a role in the pathophysiology of hypertension and cardiac failure in 2K1C hypertensive rats

Overexpression of retinoic acid-induced protein 3 predicts poor prognosis for hepatocellular carcinoma

AIM: To investigate clinical significance of retinoic acid-induced protein 3 (RAI3) in hepatocellular carcinoma (HCC). METHODS: Expression of RAI3 at both mRNA and protein levels in tumor, para-tumor and normal liver tissues was detected in 106 HCC patients by real-time quantitative RT-PCR, Western blot and immunohistochemistry. Then, the correlation of RAI3 expression with clinicopathological characteristics and survivals of HCC patients was analyzed. RESULTS: Our data first found that RAI3 mRNA and protein expression were both significantly higher in HCC than in para-tumor (both P < 0.001) and normal liver tissues (both P < 0.001). The correlation analysis showed a positive correlation between RAI3 mRNA level and RAI3 protein level in HCC tissues (r = 0.8, P < 0.001). Immunohistochemistry data also revealed that overexpression of RAI3 was present in 73.6 % (78/106) of HCC tissues. In addition, high RAI3 protein expression was correlated with advanced TNM stage (P = 0.001), high serum AFP (P = 0.008), vascular invasion (P = 0.01) and tumor recurrence (P = 0.008). Moreover, HCC patients with overexpression of RAI3 had significantly shorter overall (P = 0.01) and disease-free survival (P = 0.01). Furthermore, multivariate analysis showed that overexpression of RAI3 was an independent prognostic factor for both overall (P = 0.02) and disease-free survival (P = 0.03) in HCC. CONCLUSION: Our data for the first time provide a basis for the concept that overexpression of RAI3 may contribute to the malignant progression of HCC and predict poor prognosis for patients with this deadly disease after curative hepatectomy. RAI3 might be an important marker for tumor progression and prognosis, as well as a potential therapeutic target of HCC (AU)

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Premios Nobel de Química 2012: Una familia de receptores de membrana esencial para la comunicación celular / A essential family for cellular communication membrane receptors

El premio Nobel de Química 2012 ha sido otorgado a los investigadores estadounidenses Robert J. Lefkowitz y Brian K Kobilka por sus estudios sobre los receptores acoplados a proteínas G. Esta familia de proteínas de membrana son los sensores biológicos más extendidos y versátiles, responsables en buena medida de la capacidad de nuestras células de recibir mensajes del entorno. Son también la diana de numerosos fármacos utilizados para el tratamiento de múltiples patologías. El trabajo de Lefkowitz ha sido decisivo para desvelar la naturaleza química de estos receptores y para entender mejor sus mecanismos de señalización y de regulación. Lefkowitz y Kobilka consiguieron también identificar el gen que codificaba para el receptor beta-adrenérgico, lo que permitió posteriormente desvelar la existencia de múltiples receptores de características similares. Finalmente, Kobilka ha utilizado la difracción por rayos X para determinar la estructura íntima de estas proteínas. El camino abierto por Lefkowitz y Kobilka permitirá conocer mejor las alteraciones de receptores en situaciones patológicas y avanzar en el diseño de nuevas estrategias terapéuticas (AU)

The Nobel Prize in Chemistry 2012 has been awarded to Robert J. Lefkowitz and Brian K. Kobilka for their studies on G-protein-coupled receptors. The components of this family of membrane proteins are ubiquitous and versatile biological sensors that play an essential physiological role by allowing our cells to respond to external stimuli. GPCR also are very important pharmacological targets for the treatment of a variety of pathological conditions. The contributions of Lefkowitz have been decisive in unveiling the chemical nature of these receptors and to better understand their signaling and regulatory mechanisms. Lefkowitz and Kobilka also cloned the beta-adrenergic receptor gene and paved the way for the identification of a large family of structurally-related receptor proteins. Finally, Kobilka has recently determined the tridimensional structure of prototypical GPCRs. The work by Lefkowitz and Kobilka opens exciting avenues for a better knowledge of receptor alterations in pathological situations and for the design of novel therapeutic strategies (AU)

Expanding role for the apelin/APJ systemin physiopathology

Apelin is a bioactive peptide known as the ligand of the G protein-coupled receptorAPJ. Diverse active apelin peptides exist under the form of 13, 17 or 36 aminoacids, originated from a common 77-amino-acid precursor. Both apelin and APJmRNA are widely expressed in several rodent and human tissues and have functionaleffects in both the central nervous system and peripheral tissues. Apelin has beenshown to be involved in the regulation of cardiovascular functions, fluid homeostasis,vessel formation and cell proliferation. More recently, apelin has been describedas an adipocyte-secreted factor (adipokine), up-regulated in obesity. By acting as circulatinghormone or paracrine factor, adipokines are involved in physiological regulations(fat depot development, energy storage, metabolism or eating behavior) or inthe promotion of obesity-associated disorders (type 2 diabetes and cardiovasculardysfunctions). In this regard, expression of apelin gene in adipose tissue is increasedby insulin and TNFá. This review will consider the main roles of apelin in physiopathologywith particular attention on its role in energy balance regulation and inobesity-associated disorders (AU)

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Sistema cannabinoide endógeno: ligandos y receptores acoplados a mecanismos de transducción de señales / Endogenous cannabinoid system: ligands and receptors matched to transduction signals mechanisms

Numerosos estudios realizados en las dos últimas décadas han demostrado la existencia en el organismo animal de un sistema cannabinoide endógeno, constituido por unos ligandos, los endocannabinoides. Se han descrito dos tipos de receptores para cannabinoides: los denominados CB1, localizados preferentemente en cerebro y los CB2 que están localizados en el sistema inmune. Los dos endocannabinoides de los que más datos se dispone son la araquidoniletanolamida o anandamida y el 2-araquidonilglicerol, habiéndose postulado su posible actuación como neurotransmisores o neuromoduladores. La distribución cerebral de los endocannabinoides y de los receptores CB1 ha permitido conocer las funciones fisiológicas en las que está involucrado este sistema. Participa, a través de modular la actividad de los neurotransmisores, en la regulación del comportamiento motor y de la secreción de hormonas adenohipofisarias, interacciona con la dopamina y con el GABA, mientras que, en el caso de la memoria y el aprendizaje, lo hace con el GABA y el glutamato. La dopamina y los péptidos opioides podrían estar implicados en la participación de los endocannabinoides en el sistema de recompensa y en el control de la nocicepción. Por otro lado, la síntesis de anandamida, en condiciones de isquemia, podría jugar un papel protector en las regiones cerebrales afectadas. Se ha visto que este compuesto inhibe la captación mitocondrial de calcio y la liberación de glutamato, efectos ámbos que contribuyen a la citotoxicidad cerebral (AU)

Numerous studies carried out in the last two decades have shown the existence in the animal organism of an endogenous cannabinoide system comprising certain ligands, the endocannabinoides. Two types of receptors for cannabinoides have been described, those known as CB1, located predominantly in the brain, and the CB2 located in the immune system. The two endocannabinoides on which there is more available data are the arachidonylethanolamide or anandamide and the 2-arachidonylglycerol, their possible action as neurotransmitters or neuromodulators having been postulated. The cerebral distribution of the endocannabinoides and the CB1 receptors has led to knowledge of the physiological functions that involve this system. It participates by modulating the action of the neurotransmitters, in regulating motor behaviour and the secretion of adenohypophysary hormones, interacts with dopamine and the GABA and, in the case of memory and learning, it interacts with the GABA and the glutamate. The dopamine and the opioid peptides may be implicated in the participation of the endocannabinoides in the drug reward system and in the control of nociception. At the same time, the synthesis of anandamine in ischemia may play a protective role in the cerebral regions affected. It has been seen that this compound inhibits the mitochondrial uptake of calcium and the liberation of glutamate, both effects that contribute to cerebral cytoxicity (AU)