left-atrial-stenosis-induced-pulmonary-venous-arterialization-group-2

Left Atrial Stenosis Induced Pulmonary Venous Arterialization and Group 2 Pulmonary Hypertension in Rat

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of ...

Queen's University

The Jikei University School of Medicine

Sarcolipin (SLN) is a small proteolipid and a regulator of sarco(endo)plasmic reticulum Ca(2+)-ATPase. In heart tissue, SLN is exclusively expressed in the atrium. Previously, we inserted Cre recombinase into the endogenous SLN locus by homologous recombination and succeeded in generating SLN-Cre knockin (Sln(Cre/+)) mice. This Sln(Cre/+) mouse can be used to generate an atrium-specific gene-targeting mutant, and it is based on the Cre-loxP system. In the present study, we used adult Sln(Cre/+) mice atria and analyzed the effects of heterozygous SLN deletion by Cre knockin before use as the gene targeting mouse. Both SLN mRNA and protein levels were decreased in Sln(Cre/+) mouse atria, but there were no morphological, physiological, or molecular biological abnormalities. The properties of contractility and Ca(2+) handling were similar to wild-type (WT) mice, and expression levels of several stress markers and sarcoplasmic reticulum-related protein levels were not different between Sln(Cre/+) and WT mice. Moreover, there was no significant difference in sarco(endo)plasmic reticulum Ca(2+)-ATPase activity between the two groups. We showed that Sln(Cre/+) mice were not significantly different from WT mice in all aspects that were examined. The present study provides basic characteristics of Sln(Cre/+) mice and possibly information on the usefulness of Sln(Cre/+) mice as an atrium-specific gene-targeting model.

Heterozygous deletion of sarcolipin maintains normal cardiac function.

A rat model of left atrial stenosis-associated pulmonary hypertension due to left heart diseases was prepared to elucidate its mechanism.

Pulmonary hypertension due to left heart disease causes intrapulmonary venous arterialization in rats.

The ductus arteriosus (DA), an essential fetal shunt between the pulmonary trunk and the descending aorta, changes its structure during development. Our previous studies have demonstrated that prostaglandin E (PGE)-EP4 signaling promotes intimal cushion formation (ICF) by activating the migration of DA smooth muscle cells via the secretion of hyaluronan. We hypothesized that, in addition to hyaluronan, PGE may secrete other proteins that also regulate vascular remodeling in the DA. In order to detect PGE stimulation-secreted proteins, we found that CCN3 protein was increased in the culture supernatant in the presence of PGE in a dose-dependent manner by nano-flow liquid chromatography coupled with tandem mass spectrometry analysis and enzyme-linked immunosorbent assay. Quantitative RT-PCR analysis revealed that PGE stimulation tended to increase the expression levels of CCN3 mRNA in DA smooth muscle cells. Immunohistochemical analysis revealed that CCN3 was highly localized in the entire smooth muscle layers and the endothelium of the DA. Furthermore, exogenous CCN3 inhibited PGE-induced ICF in the ex vivo DA tissues. These results suggest that CCN3 is a secreted protein of the DA smooth muscle cells induced by PGE to suppress ICF of the DA. The present study indicates that CCN3 could be a novel negative regulator of ICF in the DA to fine-tune the PGE-mediated DA remodeling.

CCN3 secreted by prostaglandin E inhibits intimal cushion formation in the rat ductus arteriosus.

Fatty acid (FA) oxidation is impaired and glycolysis is promoted in the damaged heart. However, the factor(s) in the early stages of myocardial metabolic impairment remain(s) unclear. C57B6 mice were subcutaneously administered monocrotaline (MCT) in doses of 0.3 mg/g body weight twice a week for 3 or 6 weeks. Right and left ventricles at 3 and 6 weeks after administration were subjected to capillary electrophoresis-mass spectrometry metabolomic analysis. We also examined mRNA and protein levels of key metabolic molecules. Although no evidence of PH and right ventricular failure was found in the MCT-administered mice by echocardiographic and histological analyzes, the expression levels of stress markers such as TNFα and IL-6 were increased in right and left ventricles even at 3 weeks, suggesting that there was myocardial damage. Metabolites in the tricarboxylic acid (TCA) cycle were decreased and those in glycolysis were increased at 6 weeks. The expression levels of FA oxidation-related factors were decreased at 6 weeks. The phosphorylation level of pyruvate dehydrogenase (PDH) was significantly decreased at 3 weeks. FA oxidation and the TCA cycle were down-regulated, whereas glycolysis was partially up-regulated by MCT-induced myocardial damage. PDH activation preceded these alterations, suggesting that PDH activation is one of the earliest events to compensate for a subtle metabolic impairment from myocardial damage.

Article	Year
Heterozygous deletion of sarcolipin maintains normal cardiac function. American journal of physiology. Heart and circulatory physiology\| PubMed ID: 26519028	2016
Pulmonary hypertension due to left heart disease causes intrapulmonary venous arterialization in rats. The Journal of thoracic and cardiovascular surgery\| PubMed ID: 28755882	2017
CCN3 secreted by prostaglandin E inhibits intimal cushion formation in the rat ductus arteriosus. Biochemical and biophysical research communications\| PubMed ID: 30149912	2018
Pyruvate dehydrogenase activation precedes the down-regulation of fatty acid oxidation in monocrotaline-induced myocardial toxicity in mice. Heart and vessels\| PubMed ID: 30386918	2018

Susumu Minamisawa

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