Dataset Information

Regional Differences in the Ghrelin-Growth Hormone Secretagogue Receptor Signalling System in Human Heart Disease.

ABSTRACT:

Background

The hormone ghrelin and its receptor, the growth hormone secretagogue receptor (GHSR) are expressed in myocardium. GHSR binding activates signalling pathways coupled to cardiomyocyte survival and contractility. These properties have made the ghrelin-GHSR axis a candidate for a biomarker of cardiac function. The dynamics of ghrelin-GHSR are altered significantly in late stages of heart failure (HF) and cardiomyopathy, when left ventricular (LV) function is failing. We examined the relationship of GHSR with ghrelin in cardiac tissue from patients with valvular disease with no detectable changes in LV function.

Methods

Biopsy samples from the left ventricle and left atrium were obtained from 25 patients with valvular disease (of whom 13 also had coronary artery disease) and preserved LV ejection fraction, and compared to control samples obtained via autopsy. Using quantitative confocal fluorescence microscopy, levels of GHSR were determined using [Dpr³(n-octanoyl),Lys¹⁹(sulfo-Cy5)]ghrelin(1-19), and immunofluorescence determined ghrelin, the heart failure marker natriuretic peptide type-B (BNP), and contractility marker sarcoplasmic reticulum ATPase pump (SERCA2a).

Results

A positive correlation between GHSR and ghrelin was apparent in only diseased tissue. Ghrelin and BNP significantly correlated in the left ventricle and strongly colocalized to the same intracellular compartment in diseased and control tissue. GHSR, ghrelin, and BNP all strongly and significantly correlated with SERCA2a in the left ventricle of diseased tissue only.

Conclusions

Our results suggest that the dynamics of the myocardial ghrelin-GHSR axis is altered in cardiovascular disease in the absence of measurable changes in heart function, and might accompany a regional shift in endocrine programming.

SUBMITTER: Sullivan R

PROVIDER: S-EPMC7893201 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Regional Differences in the Ghrelin-Growth Hormone Secretagogue Receptor Signalling System in Human Heart Disease.

Sullivan Rebecca R Randhawa Varinder K VK Lalonde Tyler T Yu Tina T Kiaii Bob B Luyt Leonard L Wisenberg Gerald G Dhanvantari Savita S

CJC open 20201104 2

<h4>Background</h4>The hormone ghrelin and its receptor, the growth hormone secretagogue receptor (GHSR) are expressed in myocardium. GHSR binding activates signalling pathways coupled to cardiomyocyte survival and contractility. These properties have made the ghrelin-GHSR axis a candidate for a biomarker of cardiac function. The dynamics of ghrelin-GHSR are altered significantly in late stages of heart failure (HF) and cardiomyopathy, when left ventricular (LV) function is failing. We examined ...[more]

PMID: 33644732

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Project description:The gut hormone ghrelin is involved in numerous metabolic functions, such as the stimulation of growth hormone secretion, gastric motility, and food intake. Ghrelin is modified by ghrelin O-acyltransferase (GOAT) or membrane-bound O-acyltransferase domain-containing 4 (MBOAT4) enabling action through the growth hormone secretagogue receptors (GHS-R). During the course of evolution, initially strong ligand/receptor specificities can be disrupted by genomic changes, potentially modifying physiological roles of the ligand/receptor system. Here, we investigated the coevolution of ghrelin, GOAT, and GHS-R in vertebrates. We combined similarity search, conserved synteny analyses, phylogenetic reconstructions, and protein structure comparisons to reconstruct the evolutionary history of the ghrelin system. Ghrelin remained a single-gene locus in all vertebrate species, and accordingly, a single GHS-R isoform was identified in all tetrapods. Similar patterns of the nonsynonymous (dN) and synonymous (dS) ratio (dN/dS) in the vertebrate lineage strongly suggest coevolution of the ghrelin and GHS-R genes, supporting specific functional interactions and common physiological pathways. The selection profiles do not allow confirmation as to whether ghrelin binds specifically to GOAT, but the ghrelin dN/dS patterns are more similar to those of GOAT compared to MBOAT1 and MBOAT2 isoforms. Four GHS-R isoforms were identified in teleost genomes. This diversification of GHS-R resulted from successive rounds of duplications, some of which remained specific to the teleost lineage. Coevolution signals are lost in teleosts, presumably due to the diversification of GHS-R but not the ghrelin gene. The identification of the GHS-R diversity in teleosts provides a molecular basis for comparative studies on ghrelin's physiological roles and regulation, while the comparative sequence and structure analyses will assist translational medicine to determine structure-function relationships of the ghrelin/GHS-R system.

Project description:The growth hormone secretagogue receptor (GHSR) (ghrelin receptor) plays an important role in the regulation of food intake and energy homeostasis. The GHSR gene lies on human chromosome 3q26 within a quantitative trait locus strongly linked to multiple phenotypes related to obesity and the metabolic syndrome. Because the biological function and location of the GHSR gene make it an excellent candidate gene, we tested the relation between common single nucleotide polymorphisms (SNPs) in the GHSR gene and human obesity. We performed a comprehensive analysis of SNPs, linkage disequilibrium (LD), and haplotype structure across the entire GHSR gene region (99.3 kb) in 178 pedigrees with multiple obese members (DNA of 1,095 Caucasians) and in an independent sample of the general population (MONICA Augsburg left ventricular hypertrophy substudy; DNA of 1,418 Caucasians). The LD analysis revealed a disequilibrium block consisting of five SNPs, consistent in both study cohorts. We found linkage among all five SNPs, their haplotypes, and BMI. Further, we found suggestive evidence for transmission disequilibrium for the minor SNP alleles (P < 0.05) and the two most common haplotypes with the obesity affection status ("susceptible" P = 0.025, "nonsusceptible" P = 0.045) in the family cohort using the family-based association test program. Replication of these findings in the general population resulted in stronger evidence for an association of the SNPs (best P = 0.00001) and haplotypes with the disease ("susceptible" P = 0.002, "nonsusceptible" P = 0.002). To our knowledge, these data are the first to demonstrate linkage and association of SNPs and haplotypes within the GHSR gene region and human obesity. This linkage, together with significant transmission disequilibrium in families and replication of this association in an independent population, provides evidence that common SNPs and haplotypes within the GHSR region are involved in the pathogenesis of human obesity.

Project description:BackgroundCluster of differentiation 4 (CD4+) T cells plays a prominent role in eliminating cancer cells. The balance between T helper (Th)17 and regulatory T (Treg) cells is crucial for optimal immune response and protection against cancer. Growth hormone secretagogue receptor 1a (GHSR1a), a member of the G protein-coupled protein receptor superfamily, plays a critical role in immune cell function. The aim of our study is to investigate the role of GHSR1a in CD4+ T cell differentiation and lung cancer progression.MethodsA subcutaneous lung cancer model was used to examine the role of GHSR1a in controlling tumor growth. Lewis lung carcinoma (LLC) cells were subcutaneously implanted into Ghsr1a -/- mice and wild-type (WT) mice. The ratio of Th17 and Treg in the draining lymph node of Ghsr1a -/- mice and WT tumor-bearing mice was detected by fluorescence-activated cell sorting (FACS). The effect of GHSR1a deficiency on Th17 and Treg cell differentiation was examined using an in vitro differentiation assay. The phosphorylation of mammalian target of rapamycin (mTOR), signal transducer, and activator of transcription (STAT)3 and STAT5 signaling was detected with Western blot.ResultsWe found that the ablation of GHSR1a resulted in impaired anti-tumor immunity to control lung cancer growth in vivo. We also demonstrated that the deficiency of GHSR1a promoted a shift in the Th17/Treg balance toward enhanced Treg differentiation and inhibited Th17 differentiation both in vivo and in vitro, which suggests that GHSR1a regulates T cell lineage choices between Th17 and Treg cell commitment in the tumor microenvironment. Mechanistically, the deficiency of GHSR1a resulted in reduced phosphorylation in mTOR and STAT3, and increased phosphorylation in STAT5.ConclusionsOur findings showed the important role of GHSR1a in CD4+ T cell differentiation in the context of the lung cancer microenvironment. This research provides a novel molecular target and insights into interventions for the prevention and treatment of lung cancer.

Dataset Information

Regional Differences in the Ghrelin-Growth Hormone Secretagogue Receptor Signalling System in Human Heart Disease.

Background

Methods

Results

Conclusions

Publications

Regional Differences in the Ghrelin-Growth Hormone Secretagogue Receptor Signalling System in Human Heart Disease.

Similar Datasets

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