The vascular ANF-C receptor: role in atrial peptide signalling

Functional Analysis of Bronchopulmonary Dysplasia-Related Neuropeptides in Preterm Infants and miRNA-Based Diagnostic Model Construction

Background

Bronchopulmonary dysplasia (BPD) has a high mortality rate. This study was aimed at identifying and analysing the risk factors associated with BPD using bioinformatic and mechanical analyses and establishing a predictive model to assess the risk of BPD in preterm infants.

Methods

We identified differentially expressed RNAs via the intersection of miRNAs between datasets. Online analysis tools were used to predict genes targeted by differentially expressed miRNAs (DEmiRNAs) and to generate and visualise competing endogenous RNA (ceRNA) coexpression networks. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were subsequently performed on the DEmiRNAs. In addition, an intersection analysis was performed on mRNA and neuropeptide-related genes in the ceRNA network. DEmiRNAs associated with BPD and those involved in ceRNA networks were used to establish a diagnostic prediction model. The GSE108604 dataset was used as a validation set to verify the model.

Results

A total of 26 DEmiRNAs were identified from the tracheal aspirates (TAs) of patients with BPD and healthy controls. In addition, a total of 1076 DEmRNAs were obtained from the GSE8586 dataset. Functional enrichment analysis of DEmRNAs revealed an abnormal reduction in mitochondrial-related activity and cellular responses to oxidative stress in patients with BPD. The neuropeptide-related genes OPRL1 and NPPA were found to be upregulated in BPD samples. Eventually, hsa-miR-1258, hsa-miR-298, hsa-miR-483-3p, and hsa-miR-769-5p were screened out and used to establish the prediction model. Calibration curves and detrended correspondence analysis (DCA) revealed that the model had good clinical applicability.

Conclusions

The prediction model provided a simple method for individualised assessment, early diagnosis, and prevention of BPD risk in preterm infants.

The discovery of non-basic atrial natriuretic peptide clearance receptor antagonists. Part 1

The cyclic peptide ANP 4-23 and the linear peptide analogue AP-811 have been shown to be selective ANP-CR antagonists. Via alanine scanning and truncation studies we sought to determine which residues in these molecules were important in their binding to the clearance receptor and the relationship between these two molecules. These studies show that several modifications to these compounds are possible which improve physical properties of these molecules while retaining high affinity for the ANP-CR.

C-type natriuretic peptide attenuates evoked dopamine efflux by influencing Goalpha

-Natriuretic peptides suppress adrenergic neurotransmission by a mechanism sensitive to pertussis toxin, suggesting that GTP-binding proteins are involved in the response. The major GTP-binding proteins present in the pheochromocytoma (PC12) cells used in this report are Goalpha and Gialpha2. We tested the hypothesis that the more abundant GTP-binding protein, Goalpha, mediates natriuretic peptide effects in PC12 cells by selectively ablating Goalpha from the cells with antisense oligodeoxynucleotides. The results indicate that a selective ablation of Goalpha with this technique eliminated C-type natriuretic peptide (CNP) effects and suppressed dopamine efflux evoked by a depolarizing stimulus. However, the activation of guanylyl cyclase (GC) by CNP was sustained after the Goalpha ablation. Further, Nomega-nitro-L-arginine methyl ester suppressed evoked dopamine efflux equally in the presence and absence of Goalpha. These results suggest that CNP attenuates evoked catecholamine efflux from PC12 cells by a mechanism requiring Goalpha but independent of GC activation.

Atrial natriuretic peptide modulates alveolar type 2 cell adenylyl and guanylyl cyclases and inhibits surfactant secretion

Alveolar epithelial type 2 (T2) cells isolated from the lungs of adult rats responded to exogenous atrial natriuretic peptide (ANP) by two signalling mechanisms. First, ANP induced a dose-dependent reduction of ligand-stimulated adenylyl cyclase activity and cAMP accumulation. This effect was inhibited by the addition of GDPbetaS or by pretreatment with pertussis toxin (PT), consistent with mediation by a Gi protein(s). PT-catalyzed [32P]ADP-ribosylation, immunoblots with specific antisera, and Northern blot analysis demonstrated that T2 cells contain the G-proteins Gi2 and Gi3 which could transduce this signal. ANP also promoted PT-insensitive, dose-dependent accumulation of cGMP, consistent with activation of a receptor guanylyl cyclase. Isoproterenol-stimulated phosphatidylcholine secretion was markedly attenuated by ANP, and this effect was inhibited by PT pretreatment, consistent with mediation by a Gi protein(s). These data indicate that in addition to the lung being a major clearance organ for circulating ANP, lung parenchymal cells are targets of ANP action.