Expression Of Natriuretic Peptide Receptor Research Articles

Abstract 15171: Endothelium-Derived C-Type Natriuretic Peptide Prevents the Development and Progression of Abdominal Aortic Aneurysm

Background: Abdominal aortic aneurysm (AAA) is a life-threatening disease characterised by dilatation, inflammation and structural weakness of the abdominal aorta. Since the only effective existing intervention is surgery, development of pharmacological therapies is desperately needed. C-type natriuretic peptide (CNP) is a key endothelium-derived molecule that possesses vasodilator, anti-inflammatory and anti-atherogenic activity. Thus, we explored the role and therapeutic potential of CNP in AAA pathogenesis. Methods: Suprarenal aortic diameter was assessed by ultrasonography at baseline and following Angiotensin II (AngII, 1.44mg/kg/day) infusion in wild type (WT) or endothelium-restricted CNP deficient (ecCNP -/- ) mice infected with an AAV-expressing proprotein convertase subtilisin/kexin type 9 gain-of-function mutation (D377Y) or backcrossed on an apolipoprotein E deficient (ApoE -/- ) background. At 28 days, aortas were harvested for qRT-PCR, pharmacological assessment of vasorelaxant activity and histological analysis; plasma CNP concentrations were also determined. In some studies, CNP (0.2mg/kg/day) was infused to rescue any adverse phenotype. Results: ecCNP -/- exhibited an aggravated AAA phenotype compared to WT, exemplified by greater dilation, fibrosis and elastin degradation (without changes in blood pressure). Whilst plasma CNP concentrations were reduced in murine AAA, CNP mRNA abundance was elevated within aneurysmal tissue of ecCNP -/- , accompanied by increased abundance of mRNA encoding markers of inflammation ( IL-6, Adgre1, VCAM-1, CCL-2 ), extracellular matrix remodelling/calcification ( MMP-2, Notch-1, BMPR2, smoothelin ), fibrosis ( fibronectin ) and apoptosis ( Bax ) . CNP-induced relaxations were enhanced in aortic rings from aneurysmal tissue compared to control; an effect possibly underpinned by upregulation of natriuretic peptide receptor expression. Prophylactic administration of CNP protected against the severity of AngII-induced AAA. Conclusions: Endothelial CNP plays an important role in attenuating AAA formation by preserving aortic structure and function. Therapeutic strategies aimed at mimicking CNP bioactivity may prevent the clinical progression of AAA.

Abstract 135: The Noncoding Haplotype Region Of Blood Pressure-associated Single Nucleotide Polymorphism Rs1173771 Regulates The Expression Of Natriuretic Peptide Receptor C

Genome-wide association studies have identified 1,071 loci containing 26,585 single nucleotide polymorphisms (SNPs) as associated with blood pressure (BP). These loci together explain more than 25% of BP heritability. The BP-associated SNP rs1173771 has been associated with NPR3 expression in human tissues. NPR3 encodes natriuretic peptide receptor C (NPR-C). The haplotype in linkage disequilibrium (LD) with rs1173771 contains 11 SNPs spanning a noncoding genomic region of more than 17 kbp. The haplotype region is located 126 kbp from the transcription start site of NPR3 . We used genome editing to examine the effect of the noncoding haplotype region in LD with rs1173771 on gene expression. We employed a CRISPR/Cas9 mediated genetic engineering approach to delete the 17 kbp haplotype region in a human induced pluripotent stem cell (iPSC) line. Two clones of iPSCs with homozygous deletion of the 17 kbp region were obtained after screening 50 single cell clones. The genomic modification was confirmed by PCR, Sanger sequencing, and whole genome sequencing. Immunofluorescence staining for pluripotency markers indicated that pluripotency was retained following the genome editing procedures. Each edited iPSC clone and the unedited iPSC line were differentiated into endothelial cells (iECs) in 3 independent rounds of differentiation. Real-time PCR analysis showed a 1.59±0.17-fold upregulation of NPR3 mRNA in iECs with the haplotype region deletion compared to unedited iECs (n=11 and 7, p<0.05). The expression of other neighboring genes ( SUB1 and TARS ) and a distal gene ( MRPS30 ) was not significantly affected by the deletion. The results provide definitive evidence that the noncoding haplotype region in LD with BP-associated SNP rs1173771 regulates the expression of natriuretic peptide receptor C in iECs.

Glucocorticoids Promote Na+ Excretion in the Renal Epithelia of Heart Failure Rats by Suppressing Transporter Proteins Involved in Acute Sodium Loading.

Glucocorticoid receptors are essential for normal development and stress responses. Their role in H 2 O and Na + metabolism, especially in chronic heart failure (CHF), is not well defined. In a previous study, we found that glucocorticoids potentiate urination in CHF and promote H 2 O excretion by inhibiting the vasopressin receptor 2 pathway. The present study examines the effect of glucocorticoids on renal Na + excretion and the underlying mechanisms in CHF rats with acute sodium loading. CHF was induced by left coronary artery ligation for 8 weeks. Rats were randomly assigned to 5 groups: control, CHF, dexamethasone (DEX)-administered CHF, DEX-administered CHF treated with RU486 (mifepristone, a glucocorticoid receptor antagonist), and RU486-treated CHF. An acute sodium loading test was performed 6 hours after DEX administration. Blood and urine samples were collected, and hemodynamics were measured. The expression and localization of Na + transporter proteins were determined by immunoblotting and immunohistochemistry. DEX increased the urine volume and urinary sodium and improved cardiac function and the estimated glomerular filtration rate in CHF rats. The upregulation of the epithelial sodium channel β and γ subunits, Na-K-2Cl cotransporter, serum glucocorticoid-regulated kinase 1 (SGK1), and Na + /K + -ATPase in the renal epithelium of CHF rats was downregulated by DEX. These beneficial effects were abolished by RU486. The expression of natriuretic peptide receptor A was opposite that of the above proteins. Glucocorticoids might induce profound natriuresis in CHF rats during acute sodium loading, which is associated with downregulating some Na + transporter proteins in the renal epithelium and improving intrarenal hemodynamics.

Sacubitril/valsartan treatment relieved the progression of established pulmonary hypertension in rat model and its mechanism

AimsPulmonary hypertension (PH) is a fatal disease identified by progressive elevated pulmonary arterial pressure, which neurohormonal activation is a notable contributor to its development. Sacubitril/valsartan is a complex of sacubitril [via enhancing the natriuretic peptide (NP) system] and valsartan [via blocking the renin-angiotensin-aldosterone system (RAAS)]. Regulation of the two neurohormonal system had been shown to attenuate PH. This study was to explore the role of sacubitril/valsartan in both monocrotaline (MCT)-induced and hypoxia-induced rat models and the underlying mechanism. Main methodsThe rats were treated with MCT or hypoxic environment for 14 days, after that sacubitril/valsartan were given for another 14 days. Hemodynamic measurements and histological assessments were performed. The expression of NPs was measured using RT-PCR and ELISA, while the protein level of natriuretic peptide receptors (NPRs) and AT1 receptor were detected by western blot, the concentrations of cGMP, IL-1β, IL-6, TNF-α and TGF-β1 were tested by ELISA. Key findingsWe found that sacubitril/valsartan significantly improved the hemodynamic and histological data of two PH models. Sacubitril/valsartan suppressed the protein expression of AT1 receptor (P < 0.05). The intervention increased the expression of ANP and CNP (P< 0.05) and therefore upregulated the protein expression of NPRs (P < 0.05), raised the concentration of cGMP (P < 0.05). In addition, the treatment reduced the concentration of IL-1β, IL-6 and TNF-α (P < 0.05) but have no effects on TGF-β1. SignificanceSacubitril/valsartan alleviated PH in MCT-induced and hypoxia-induced rat models by inhibiting the activated RAAS, promoting ANP/NPR-A/cGMP and CNP/NPR-B/cGMP pathway, restoring the NPR-C signaling and the anti-inflammatory effects.

Sex-Mediated Response to the Beta-Blocker Landiolol in Sepsis: An Experimental, Randomized Study.

To investigate any gender effect of the beta-1 adrenergic blocker, landiolol, on cardiac performance and energy metabolism in septic rats, and to explore the expression of genes and proteins involved in this process. Randomized animal study. University research laboratory. Male and female Wistar rats. One hour after cecal ligation and puncture, male and female rats were randomly allocated to the following groups: sham male, cecal ligation and puncture male, cecal ligation and puncture + landiolol male, sham female, cecal ligation and puncture female, and cecal ligation and puncture + landiolol female. Cardiac MRI was carried out 18 hours after cecal ligation and puncture to assess in vivo cardiac function. Ex vivo cardiac function measurement and P magnetic resonance spectroscopy were subsequently performed using an isovolumic isolated heart preparation. Finally, we assessed cardiac gene and protein expression. In males, landiolol increased indexed stroke volume by reversing the indexed end-diastolic volume reduction without affecting left ventricle ejection fraction. In females, landiolol did not increase indexed stroke volume and indexed end-diastolic volume but decreased left ventricle ejection fraction. Landiolol had no effect on ex vivo cardiac function and on high-energy phosphate compounds. The effect of landiolol on the gene expression of natriuretic peptide receptor 3 and on protein expression of phosphorylated-AKT:AKT ratio and endothelial nitric oxide synthase was different in males and females. Landiolol improved the in vivo cardiac performance of septic male rats while deleterious effects were reported in females. Expression of natriuretic peptide receptor 3, phosphorylated-AKT:AKT, and endothelial nitric oxide synthase are signaling pathways to investigate to better understand the sex differences in sepsis.

Embryonal brain tumor with unknown primary lesion and massive cerebrospinal fluid dissemination: A case report

The 2007 World Health Organization Classification of Tumors of the Central Nervous System (CNS) categorized embryonal tumors of the CNS into three classes: medulloblastoma, CNS primitive neuroectodermal tumor, and atypical teratoid/rhabdoid tumor. Due to the lack of specific histological features, it was sometimes difficult to accurately differentiate CNS embryonal tumors pathologically.Here, we report a case of a young man, who presented with headache. Gadolinium-enhanced magnetic resonance imaging demonstrated massive lesions in the cerebrospinal fluid space, which strongly suggested leptomeningeal dissemination of a brain tumor. The histology showed the tumor comprised densely packed, small cells with scant cytoplasm. Immunoreactivities were positive for synaptophysin and chromogranin A, and negative for glial fibrillary acidic protein, S-100, EMA, and CD20. Because the tumors were located in multiple sites and most of them were within the cerebrospinal fluid space, the primary lesion could not be determined. We diagnosed this case as ‘CNS primitive neuroectodermal tumor’ by the patient age and predominantly supratentorial distribution of the lesions. After the induction therapy, WHO published its updated classification in 2016. Considering the possibility that the diagnosis is medulloblastoma, we performed additional immunohistochemical analyses, and diagnosed Group 3 medulloblastoma because of the expression of natriuretic peptide receptor 3.

Molecular mechanisms underlying the neuroprotective role of atrial natriuretic peptide in experimental acute ischemic stroke.

Along with its role in regulating blood pressure and fluid homeostasis, the natriuretic peptide system could be also part of an endogenous protective mechanism against brain damage. We aimed to assess the possibility that exogenous atrial natriuretic peptide (ANP) could protect against acute ischemic stroke, as well as the molecular mechanisms involved. Three groups of rats subjected to transient middle cerebral artery occlusion (tMCAO, intraluminal filament technique, 60 min) received intracerebroventricular vehicle, low-dose ANP (0.5 nmol) or high-dose ANP (2.5 nmol), at 30 min reperfusion. Neurofunctional condition, and brain infarct and edema volumes were measured at 24 h after tMCAO. Apoptotic cell death and expression of natriuretic peptide receptors (NPR-A and NPR-C), K+ channels (KATP, KV and BKCa), and PI3K/Akt and MAPK/ERK1/2 signaling pathways were analyzed. Significant improvement in neurofunctional status, associated to reduction in infarct and edema volumes, was shown in the high-dose ANP group. As to the molecular mechanisms analyzed, high-dose ANP: 1) reduced caspase-3-mediated apoptosis; 2) did not modify the expression of NPR-A and NPR-C, which had been downregulated by the ischemic insult; 3) induced a significant reversion of ischemia-downregulated KATP channel expression; and 4) induced a significant reversion of ischemia-upregulated pERK2/ERK2 expression ratio. In conclusion, ANP exerts a significant protective role in terms of both improvement of neurofunctional status and reduction in infarct volume. Modulation of ANP on some molecular mechanisms involved in ischemia-induced apoptotic cell death (KATP channels and MAPK/ERK1/2 signaling pathway) could account, at least in part, for its beneficial effect. Therefore, ANP should be considered as a potential adjunctive neuroprotective agent improving stroke outcome after successful reperfusion interventions.

Effects of pre-incubation with C-type natriuretic peptide on nuclear maturation, mitochondrial behavior, and developmental competence of sheep oocytes

In vitro produced mammalian embryos suffer from developmental failure, with a large proportion showing embryonic retardation, degradation, or apoptosis. This failure is due, in part, to incomplete oocyte cytoplasmic maturation. C-type natriuretic peptide (CNP) has been reported to act as a meiotic inhibitor. Here we explored the potential effects of CNP pre-treatment sheep oocytes on nuclear maturation, changes in mitochondrial behavior and developmental competence of in vitro fertilized embryos. Sheep cumulus–oocyte complexes (COCs) were aspirated from abattoir-derived ovaries. Nuclear progression was assessed using DAPI chromatin staining, the expression of natriuretic peptide receptor 2 (NPR2) was evaluated by RT-qPCR, active mitochondria localization was assessed with a confocal laser scanning microscopy using MitoTracker Red, and the developmental competence of sheep oocytes subjected to one-step IVM or two-step IVM with or without CNP pretreatment was also investigated. Our results showed that 200 nM CNP could effectively maintain meiotic arrest of sheep COCs in vitro within 4 h. Furthermore, NPR2 mRNA was mainly expressed in cumulus cells. COCs pre-treated with 200 nM CNP for 4 h followed by 24 h IVM showed significantly higher (P < 0.05) cleavage rate and blastocyst rate after in vitro fertilization (IVF), and significantly lower (P < 0.05) proportion of DNA-fragmented nuclei in blastocysts when compared to the conventional 24 h IVM (standard IVM). Non-matured oocytes mainly displayed brilliant circumferential and fine diffuse distribution of mitochondria throughout the cytoplasm. By comparison, 200 nM CNP pre-treated COCs for 4 h led to cytoplasmic mitochondrial granule localization to the peripheral and perinuclear regions. Moreover, oocytes pre-treated with 200 nM CNP for 4 h followed by 24 h IVM, showed mitochondrial organization were similar to those of conventional 24 h matured oocytes in which mitochondria were aggregated more toward the cortical regions of the oocytes, but with larger clumps of stained mitochondria. These results indicate that CNP pre-treatment improves the quality and developmental competence of sheep oocytes and has great potential for facilitating in vitro embryo production.

Alteration of Renal Natriuretic Systems Is Associated with the Development of Hypertension and Precedes the Presence of Renal Damage in a Model of Metabolic Syndrome

Objective: The aim of this study was to determine the presence of alterations in the natriuretic systems of atrial natriuretic peptide and renal dopamine in a model of metabolic syndrome induced by fructose overload and to associate them with changes in systolic blood pressure, renal function, Na+/K+-ATPase status and microalbuminuria. Methods: Male Sprague-Dawley rats were divided into control (C) and fructose (F) groups receiving drinking water or a fructose solution (10% W/V), respectively, for 4, 8 and 12 weeks. L-dopa and dopamine, sodium, creatinine and albumin were measured in urine and ANP, insulin, sodium and creatinine in plasma. Systolic blood pressure was measured by indirect method and the renal activity and expression of Na+/K+-ATPase as well as the renal expression of A- and C-type natriuretic peptide receptors were assessed. Results: Fructose overload was associated with a significant increase in insulinemia and systolic blood pressure levels and a decrease in urinary sodium excretion since week 4. A significant increase in L-dopa excretion and a decrease in dopamine excretion (increased urinary L-dopa/dopamine ratio) due to fructose overload were observed since week 4 with a decrease in plasma atrial natriuretic peptide at weeks 8 and 12. These changes were accompanied by increased activity and expression of Na+/ K+-ATPase, decreased A-type natriuretic peptide receptor and increased C-type natriuretic peptide receptor expression. Microalbuminuria was observed at week 12 of fructose overload. 1

Mechanisms involved in the increased sensitivity of the rabbit basilar artery to atrial natriuretic peptide in diabetes

Atrial natriuretic peptide (ANP) is a vasodilator with significant regional differences and controversial effects in the cerebral circulation, a vascular bed particularly prone to diabetes-induced complications. The present study has investigated how alloxan-induced diabetes modifies the mechanisms involved in the response of the rabbit basilar artery to ANP. ANP (10–12–10−7M) relaxed precontracted basilar arteries, with higher potency in diabetic than in control rabbits. In arteries from both groups of animals, endothelium removal reduced ANP-induced relaxations. Inhibition of NO-synthesis attenuated ANP-induced relaxation but this attenuation was lower in diabetic than in control rabbits. In control rabbits, indomethacin displaced to the left the concentration-response curve to ANP, without significantly modifying the Emax value. In diabetic rabbits, indomethacin significantly enhanced arterial relaxations to ANP. In KCl-depolarised arteries, relaxation to ANP was almost abolished both in control and in diabetic rabbits. Iberiotoxin inhibited relaxations to ANP in both groups of rabbits. Glibenclamide and 4-aminopyridine inhibited the ANP-induced relaxations more in diabetic than in control rabbits. Basilar arteries from diabetic rabbits showed decreased natriuretic peptide receptor C expression and no changes in natriuretic peptide receptor A, large conductance calcium-activated K+ channels (BKCa), ATP-sensitive K+ channels (KATP) and voltage-sensitive K+ channels (KV) expression. These results suggest that diabetes enhances the sensitivity of the rabbit basilar artery to ANP by mechanisms that at least include reduced expression of natriuretic peptide receptor C, and enhanced activity of KATP and KV channels. Furthermore, diabetes reduces endothelial NO and prostacyclin which mediate arterial relaxation to ANP.

The effects of valproic acid on the mRNA expression of Natriuretic Peptide Receptor A and KQT-like subfamily Q-1 in human colon cancer cell lines

Aim and objectivesThe histone deacetylase (HDAC) inhibitor, Valproic Acid (VPA), causes growth inhibition and apoptosis in colorectal cancer cells. HDAC inhibition is associated with the transcriptional regulation of Natriuretic Peptide Receptor-A (NPR-A). NPR-A regulates voltage-gated potassium channel, KQT-like subfamily Q, member 1 (KCNQ1). NPR-A and KCNQ1 are also involved in the initiation and propagation of cancer cells. In this study, we investigated the simultaneous expressional changes of NPR-A and KCNQ1 among VPA-treated colon cancer cells. Materials and methodsHuman colorectal cancer cells were cultured and treated with increasing concentrations of VPA at different time points. MTT viability test was conducted to evaluate the growth inhibition. Real Time RT-PCR was used to quantify differential mRNA expression of NPR-A and KCNQ1 genes. Two-way ANOVA and bonferroni post-tests were used to analyze data statistically. ResultsWe showed that VPA treatment inhibits the growth of SW-480 cells more efficiently compared to HT-29. NPR-A and KCNQ1 genes were significantly upregulated upon VPA treatment in both cell lines (P<0.0001). ConclusionThe alteration of NPR-A and KCNQ1 genes were more ordered among SW-480 cancer cells. The expressional changes of KCNQ1 and NPR-A among VPA treated human colon cancer cells follow the same pattern in similar combinations. VPA could regulate the expression of KCNQ1 through altering the mRNA expression of NPR-A.

Enhanced expression of natriuretic peptide receptor A and B in neutrophils of culprit lesions in patients with acute myocardial infarction.

Natriuretic peptides and their specific receptors have been suggested to have regulatory effects on smooth muscle cell (SMC) growth and inflammatory cell reactions. However, the roles of natriuretic peptide receptor A (NPR‑A) and B (NPR‑B) in unstable plaques remain to be studied in detail. Frozen sections from 82 coronary artery segments were used. These segments were obtained at autopsy from 13patients with acute myocardial infarction (AMI; 7 ruptured and 6 eroded plaques) and from 30patients with non‑cardiovascular diseases. Antibodies against SMCs, endothelial cells, macrophages, neutrophils, NPR‑A, NPR‑B and neutral endopeptidase (NEP) were used. Neutrophil infiltration was identified in all lesions with plaque rupture or erosion. Double immunostaining identified that the majority of NPR‑A‑ or NPR‑B‑positive cells were neutrophils in ruptured and eroded plaques. Using morphometric analysis, no significant difference was observed in the percentage of NPR‑A‑ and NPR‑B‑positive cells between ruptured and eroded plaques, while the number of NEP‑positive neutrophils in ruptured plaques was significantly higher compared with eroded plaques(P<0.0001). These results of the distinct presence of NPR‑A‑ and NPR‑B‑positive cells in unstable plaques underlying AMI suggested that natriuretic peptides serve a role in regulating plaque instability in humans.

Neutral endopeptidase and natriuretic peptide receptors participate in the regulation of C-type natriuretic peptide expression in renal interstitial fibrosis

The initiation and progression of renal interstitial fibrosis (RIF) is a complicated process in which many factors may play an activate role. Among these factors, C-type natriuretic peptide (CNP) is an endothelium-derived hormone and acts in a local, paracrine fashion to regulate vascular smooth muscle tone and proliferation. In this study, we established a rat model of unilateral ureteral obstruction (UUO). CNP expression tends to be higher immediately after ligation and declined at later time points, occurring predominantly in tubular epithelial cells. A high-level CNP may contribute to the elevated expression of natriuretic peptide receptor (NPR)-B in the early phase of UUO. However, the sustained expression of NPR-C and neutral endopeptidase (NEP) observed throughout the study period (that is up to 3 months) helps to, at least partly, explain the subsequent decline of CNP. Thus, NEP and NPRs participate in the regulation of CNP expression in RIF.

Adipose tissue natriuretic peptide receptor expression is related to insulin sensitivity in obesity and diabetes

ObjectiveCardiac natriuretic peptides (NPs) bind to two receptors (NPRA‐mediator of signaling; NPRC‐clearance receptor) whose ratio, NPRR (NPRA/NPRC), determines the NP bioactivity. This study investigated the relationship of NP receptor gene expression in adipose tissue and muscle with obesity and glucose intolerance. Prospectively, the study also assessed whether changes in NP receptor expression and thermogenic gene markers accompanied improvements of insulin sensitivity.MethodsA cross‐sectional study of subjects with a wide range of BMI and glucose tolerance (n = 50) was conducted, as well as a randomized 12‐week trial of subjects with type 2 diabetes mellitus (T2DM) treated with pioglitazone (n = 9) or placebo (n = 10).ResultsNPRR mRNA was significantly lower in adipose tissue of subjects with obesity when compared with lean subjects (P ≤ 0.001). NPRR decreased with progression from normal glucose tolerance to T2DM (P < 0.01) independently of obesity. Treatment of subjects with T2DM with pioglitazone increased NPRR in adipose tissue (P ≤ 0.01) in conjunction with improvements in insulin sensitivity and increases of the thermogenic markers PPARγ coactivator‐1α and uncoupling protein 1 (P ≤ 0.01).ConclusionsDecreased adipose tissue NPRR was associated with obesity, glucose intolerance, and insulin resistance. This relationship was not observed for skeletal muscle NPRR. Pharmacological improvement of insulin sensitivity in subjects with T2DM was tied to improvement in NPRR and increased expression of genes involved in thermogenic processes.

NPs/NPRs Signaling Pathways May Be Involved in Depression-Induced Loss of Gastric ICC by Decreasing the Production of mSCF.

It is well known that natriuretic peptides (NPs) are involved in the regulation of gastrointestinal motility. Interstitial cells of Cajal (ICC) are the pacemaker cells of gastrointestinal motility and gastrointestinal dyskinesia is one of the important digestive tract symptoms of depression. However, it is unclear whether they are involved in depression-induced loss of ICC. The aim of the present study was to investigate the relationship between the natriuretic peptide signaling pathway and depression-induced loss of gastric ICC in depressed rats. These results showed that the expression of c-kit and stem cell factor (SCF) in smooth muscle layers of stomach were down-regulated in depressed rats at the mRNA and protein levels. The expression of natriuretic peptide receptor (NPR)-A, B and C were up-regulated in the stomach of depressed rats at the mRNA and protein levels. NPR-A, B and C can significantly decrease the expression of SCF to treat cultured gastric smooth muscle cells (GSMCs) obtained from normal rats with different concentrations of C-type natriuretic peptide (CNP). Pretreatment of cultured GSMCs with 8-Brom-cGMP (8-Br-cGMP, a membrane permeable cGMP analog), cANF (a specific NPR-C agonist) and CNP (10−6 mol/L) demonstrated that 8-Br-cGMP had a similar effect as CNP, but treatment with cANF did not. The results of the methyl thiazolyl tetrazolium bromide (MTT) assay indicated that high concentrations of cANF (10−6 mol/L) restrained the proliferation of cultured GSMCs. Taken together, these results indicate that the up-regulation of the NPs/NPR-C and NPs/NPR-A, B/cGMP signaling pathways may be involved in depression-induced loss of gastric ICC.

C-type atriuretic peptide causes relaxation of the internal anal sphincter through natriuretic peptide receptor B

ObjectivesThe internal anal sphincter (IAS) plays an important role in maintaining continence. Atrial natriuretic peptide (ANP) could relax the IAS. The purpose of the present study was to investigate the roles of natriuretic peptide receptors (NPRs) in the IAS. Materials and methodsRelaxation of isolated rat IAS strips caused by natriuretic peptides was measured using isometric transducers. Expression of NPRs was evaluated by reverse transcription–polymerase chain reaction (PCR), immunohistochemistry and real-time PCR. ResultsIn the rat IAS, C-type natriuretic peptide (CNP) produced a marked and concentration-dependent relaxation while ANP caused a mild relaxation. By contrast, brain natriuretic peptide, dendroaspis natriuretic peptide, and des[Gln18, Ser19, Gly20, Leu21, Gly22]ANP(4–23) amide did not generate relaxation. CNP was much more effective than ANP and brain natriuretic peptide in stimulating the relaxation, indicating that NPR-B mediates IAS relaxation. The CNP-induced relaxation was inhibited by the protein kinase G inhibitor Rp-8CPT-cGMPS and potassium channel blocker charybdotoxin but not by protein kinase A inhibitor Rp-cAMPS. This suggests the involvement of cGMP and calcium-activated potassium channels in the CNP-induced IAS relaxation. Reverse transcription PCR and immunohistochemistry revealed the existence of NPR-B in the rat IAS. Furthermore, real-time PCR identified abundant expression of CNP and NPR-B in the rat IAS. ConclusionCNP causes relaxation of the IAS via NPR-B, cGMP, and potassium channel pathways in rats. CNP might regulate IAS motility. NPR-B is a potential therapeutic target in anorectal motility disorders.

Glipizide, an antidiabetic drug, suppresses tumor growth and metastasis by inhibiting angiogenesis.

Angiogenesis is involved in the development, progression and metastasis of various human cancers. Herein, we report the discovery of glipizide, a widely used drug for type 2 diabetes mellitus, as a promising anticancer agent through the inhibition of tumor angiogenesis. By high-throughput screening (HTS) of an FDA approved drug library utilizing our in vivo chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) models, glipizide has been identified to significantly inhibit blood vessel formation and development. Moreover, glipizide was found to suppress tumor angiogenesis, tumor growth and metastasis using xenograft tumor and MMTV-PyMT transgenic mouse models. We further revealed that the anticancer capability of glipizide is not attributed to its antiproliferative effects, which are not significant against various human cancer cell lines. To investigate whether its anticancer efficacy is associated with the glucose level alteration induced by glipizide application, glimepiride, another medium to long-acting sulfonylurea antidiabetic drug in the same class, was employed for the comparison studies in the same fashion. Interestingly, glimepiride has demonstrated no significant impact on the tumor growth and metastasis, indicating that the anticancer effects of glipizide is not ascribed to its antidiabetic properties. Furthermore, glipizide suppresses endothelial cell migration and the formation of tubular structures, thereby inhibiting angiogenesis by up-regulating the expression of natriuretic peptide receptor A. These findings uncover a novel mechanism of glipizide as a potential cancer therapy, and also for the first time, provide direct evidence to support that treatment with glipizide may reduce the cancer risk for diabetic patients.

NPR2, SMAD2/3, BMP and GDF-9 expressions in human granulosa and cumulus cells during oocyte maturation

We compare expression of Natriuretic Peptide Receptor 2 (NPR2), SMAD2/3, bone morphogenetic proteins (BMP) receptor 2 (BMPR2), BMP15 and growth differentiation factor 9 (GDF-9) mRNA levels in human GCs and CCs in young and older IVF patients. NPR2 is an oocyte meiotic maturation inhibitor that maintains meiotic arrest. Its role in oocyte maturation is not well understood. SMAD2/3 are transcription factors that transduce TGF-β superfamily ligand signals from membrane-bound TGF-β receptors into nucleus, inducing TGF-β target gene expression associated with cumulus expansion.

Gestational hypertension in atrial natriuretic peptide knockout mice and the developmental origins of salt-sensitivity and cardiac hypertrophy

ObjectiveTo determine the effect of gestational hypertension on the developmental origins of blood pressure (BP), altered kidney gene expression, salt-sensitivity and cardiac hypertrophy (CH) in adult offspring. MethodsFemale mice lacking atrial natriuretic peptide (ANP−/−) were used as a model of gestational hypertension. Heterozygous ANP+/− offspring was bred from crossing either ANP+/+ females with ANP−/− males yielding ANP+/−WT offspring, or from ANP−/− females with ANP+/+ males yielding ANP+/−KO offspring. Maternal BP during pregnancy was measured using radiotelemetry. At 14weeks of age, offspring BP, gene and protein expression were measured in the kidney with real-time quantitative PCR, receptor binding assay and ELISA. ResultsANP+/−KO offspring exhibited normal BP at 14weeks of age, but displayed significant CH (P<0.001) as compared to ANP+/−WT offspring. ANP+/−KO offspring exhibited significantly increased gene expression of natriuretic peptide receptor A (NPR-A) (P<0.001) and radioligand binding studies demonstrated significantly reduced NPR-C binding (P=0.01) in the kidney. Treatment with high salt diet increased BP (P<0.01) and caused LV hypertrophy (P<0.001) and interstitial myocardial fibrosis only in ANP+/−WT and not ANP+/−KO offspring, suggesting gestational hypertension programs the offspring to show resistance to salt-induced hypertension and LV remodeling. Our data demonstrate that altered maternal environments can determine the salt-sensitive phenotype of offspring.

Isolation, homology modeling and renal effects of a C-type natriuretic peptide from the venom of the Brazilian yellow scorpion (Tityus serrulatus)

Mammalian natriuretic peptides (NPs) have been extensively investigated for use as therapeutic agents in the treatment of cardiovascular diseases. Here, we describe the isolation, sequencing and tridimensional homology modeling of the first C-type natriuretic peptide isolated from scorpion venom. In addition, its effects on the renal function of rats and on the mRNA expression of natriuretic peptide receptors in the kidneys are delineated. Fractionation of Tityus serrulatus venom using chromatographic techniques yielded a peptide with a molecular mass of 2190.64 Da, which exhibited the pattern of disulfide bridges that is characteristic of a C-type NP (TsNP, T. serrulatus Natriuretic Peptide). In the isolated perfused rat kidney assay, treatment with two concentrations of TsNP (0.03 and 0.1 μg/mL) increased the perfusion pressure, glomerular filtration rate and urinary flow. After 60 min of treatment at both concentrations, the percentages of sodium, potassium and chloride transport were decreased, and the urinary cGMP concentration was elevated. Natriuretic peptide receptor-A (NPR-A) mRNA expression was down regulated in the kidneys treated with both concentrations of TsNP, whereas NPR-B, NPR-C and CG-C mRNAs were up regulated at the 0.1 μg/mL concentration. In conclusion, this work describes the isolation and modeling of the first natriuretic peptide isolated from scorpion venom. In addition, examinations of the renal actions of TsNP indicate that its effects may be related to the activation of NPR-B, NPR-C and GC-C.