Atrial Natriuretic Peptide Receptor Research Articles

Corin Deficiency Diminishes Intestinal Sodium Excretion in Mice.

Sodium excretion, a critical process in sodium homeostasis, occurs in many tissues, including the kidney and intestine. Unlike in the kidney, the hormonal regulation of intestinal sodium excretion remains unclear. Atrial natriuretic peptide (ANP) is a crucial hormone in renal natriuresis. Corin is a protease critical for ANP activation. Corin and ANP are expressed mainly in the heart. In this study, we investigated corin, ANP, and natriuretic peptide receptor A (Npra) expression in mouse intestines. Corin and ANP expression was co-localized in enteroendocrine cells, whereas Npra expression was on the luminal epithelial cells. In Corin knockout (KO) mice, fecal Na+ and Cl- excretion decreased compared with that in wild-type (WT) mice. Such a decrease was not found in conditional Corin KO mice lacking cardiac corin selectively. In kidney conditional Corin KO mice lacking renal corin, fecal Na+ and Cl- excretion increased, compared to that in WT mice. When WT, Corin KO, and the kidney conditional KO mice were treated with aldosterone, the differences in fecal Na+ and Cl- levels disappeared. These results suggest that intestinal corin may promote fecal sodium excretion in a paracrine mechanism independent of the cardiac corin function. The increased fecal sodium excretion in the kidney conditional Corin KO mice likely reflected an intestinal compensatory response to renal corin deficiency. Our results also suggest that intestinal corin activity may antagonize aldosterone action in the promotion of fecal sodium excretion. These findings help us understand the hormonal mechanism controlling sodium excretion the intestinal tract.

Investigating the Effects of Atrial Natriuretic Peptide on the Maternal Endothelium to Determine Potential Implications for Preeclampsia.

Preeclampsia is associated with an increased lifelong risk of cardiovascular disease (CVD). It is not clear whether this is induced by persistent systemic organ and vascular damage following preeclampsia or due to a predisposition to both conditions that share cardiovascular pathophysiology. Common to both CVD and preeclampsia is the dysregulation of corin and its proteolytic product, atrial natriuretic peptide (ANP). ANP, a hypotensive hormone converted from pro-ANP by corin, is involved in blood pressure homeostasis. While corin is predominantly a cardiac enzyme, both corin and pro-ANP are significantly upregulated in the gravid uterus and dysregulated in preeclampsia. Relatively little is known about ANP function in the endothelium during a pregnancy complicated by preeclampsia. Here, we investigated the effect of ANP on endothelial cell proliferation and migration, markers of endothelial dysfunction, and receptor expression in omental arteries exposed to circulating preeclamptic toxins. ANP receptor expression is significantly upregulated in preeclamptic vasculature but not because of exposure to preeclampsia toxins tumour necrosis factor α or soluble fms-like tyrosine kinase-1. The supplementation of endothelial cells with ANP did not promote proliferation or migration, nor did ANP improve markers of endothelial dysfunction. The role of ANP in preeclampsia is unlikely to be via endothelial pathways.

PPAR Alpha Activation by Clofibrate Alleviates Ischemia/Reperfusion Injury in Metabolic Syndrome Rats by Decreasing Cardiac Inflammation and Remodeling and by Regulating the Atrial Natriuretic Peptide Compensatory Response.

Metabolic syndrome (MetS) is a cluster of factors that increase the risk of developing diabetes, stroke, and heart failure. The pathophysiology of injury by ischemia/reperfusion (I/R) is highly complex and the inflammatory condition plays an important role by increasing matrix remodeling and cardiac apoptosis. Natriuretic peptides (NPs) are cardiac hormones with numerous beneficial effects mainly mediated by a cell surface receptor named atrial natriuretic peptide receptor (ANPr). Although NPs are powerful clinical markers of cardiac failure, their role in I/R is still controversial. Peroxisome proliferator-activated receptor α agonists exert cardiovascular therapeutic actions; however, their effect on the NPs' signaling pathway has not been extensively studied. Our study provides important insight into the regulation of both ANP and ANPr in the hearts of MetS rats and their association with the inflammatory conditions caused by damage from I/R. Moreover, we show that pre-treatment with clofibrate was able to decrease the inflammatory response that, in turn, decreases myocardial fibrosis, the expression of metalloprotease 2 and apoptosis. Treatment with clofibrate is also associated with a decrease in ANP and ANPr expression.

Роль генов систем натрийуретических пептидов и антиоксидантной защиты в формировании риска развития инфаркта миокарда (предварительные результаты пилотного исследования)

Aim: to reveal a relationship of single-nucleotide polymorphic variants of the genes of the natriuretic peptides, antioxidant defense systems and the endothelial function with the development of myocardial infarction. Patients and Methods: the study included 146 patients with myocardial infarction (MI) and maintained or moderately decreased left ventricular ejection fraction: 108 males and 38 females with a mean age of 57 (51; 64) years. The control group was composed of Kemerovo city residents without acute MI (n=300, 190 females and 110 males). To make the evaluation, genomic DNA was isolated from the peripheral blood by phenol- chloroform extraction according to the standard protocol. Real-time PCR method was used for genotyping. To conduct the study, 24 polymorphic variants of 14 genes (those of the natriuretic peptides, antioxidant defense systems and the endothelial function) were selected. Results: significant associations with the allelic variants of CBR1 and CBR3 genes (carbonyl reductase 1 and 3 genes) of the antioxidant defense system were found in the sample of studied patients with MI (not divided by gender or age). When the patients were divided by gender, the following associations were found: in males the single-nucleotide polymorphic variant (SNPV) genotypes CBR1 rs9024 and CBR3 rs1056892 had the protective effect against susceptibility to myocardial infarction (dominant inheritance pattern). It was demonstrated that allelic variants in the NPR2 gene (the gene of atrial natriuretic peptide receptor 2) comprised a risk factor for MI development. In females, a relationship between the assessed genetic factors and the MI development (dominant inheritance pattern) could be associated with SNPV genotypes NPR2 rs13288085 and rs7034957, CBR1 rs9024, and CBR3 rs1056892 which are characterized by the protective effect. Conclusion: some polymorphic variants of the genes of the natriuretic peptide and antioxidant defense systems are associated with the risk and the protective effect against MI susceptibility. The preliminary findings indicate that it is necessary to continue investigations of the identified single-nucleotide polymorphic variants and to assess their impact on the MI severity and the risk of recurrent cardiovascular events in the long-term perspective. KEYWORDS: myocardial infarction, gene, natriuretic peptides, antioxidant defense, polymorphic variants. FOR CITATION: Khutornaya M.V., Khryachkova O.N., Sinitskaya A.V. et al. Role of the genes of the natriuretic peptide and antioxidant defense systems in creating the risk of myocardial infarction development (the preliminary results of a pilot study). Russian Medical Inquiry. 2023;7(1):5–12 (in Russ.). DOI: 10.32364/2587-6821-2023-7-1-5-12.

A slit-diaphragm-associated protein network for dynamic control of renal filtration

The filtration of blood in the kidney which is crucial for mammalian life is determined by the slit-diaphragm, a cell-cell junction between the foot processes of renal podocytes. The slit-diaphragm is thought to operate as final barrier or as molecular sensor of renal filtration. Using high-resolution proteomic analysis of slit-diaphragms affinity-isolated from rodent kidney, we show that the native slit-diaphragm is built from the junction-forming components Nephrin, Neph1 and Podocin and a co-assembled high-molecular weight network of proteins. The network constituents cover distinct classes of proteins including signaling-receptors, kinases/phosphatases, transporters and scaffolds. Knockout or knock-down of either the core components or the selected network constituents tyrosine kinase MER (MERTK), atrial natriuretic peptide-receptor C (ANPRC), integral membrane protein 2B (ITM2B), membrane-associated guanylate-kinase, WW and PDZ-domain-containing protein1 (MAGI1) and amyloid protein A4 resulted in target-specific impairment or disruption of the filtration process. Our results identify the slit-diaphragm as a multi-component system that is endowed with context-dependent dynamics via a co-assembled protein network.

Role of atrial natriuretic peptide receptor in inhibition of laterally spreading tumors via Wnt/β-catenin signaling

Colorectal cancer (CRC) is the third most prevalent malignancy worldwide. Laterally spreading tumors (LSTs), as special manifestations of digestive tract tumors, are often misdiagnosed or undiagnosed due to their unique morphological and pathological features. LST has no protruding lesions and progresses rapidly, and prognoses are consequently poor. LST progression to CRC is complicated. Clinical data indicate that the heart is rarely the site of primary tumorigenesis, and a class of atrial natriuretic peptides (ANPs) secreted by heart tissue play an important role in this phenomenon, which is closely related to the Wnt/β-catenin signaling pathway. However, previous studies focused solely on correlations between the Wnt/β-catenin signaling pathway, downstream gene expression and LST. Thus, correlational studies of ANP/ANP receptor, LST and CRC may be of great help in understanding the occurrence, development and treatment of LST, as well as in establishing specific and sensitive methods for detecting LST.

ROS and cGMP signaling modulate persistent escape from hypoxia in Caenorhabditis elegans.

The ability to detect and respond to acute oxygen (O2) shortages is indispensable to aerobic life. The molecular mechanisms and circuits underlying this capacity are poorly understood. Here, we characterize the behavioral responses of feeding Caenorhabditis elegans to approximately 1% O2. Acute hypoxia triggers a bout of turning maneuvers followed by a persistent switch to rapid forward movement as animals seek to avoid and escape hypoxia. While the behavioral responses to 1% O2 closely resemble those evoked by 21% O2, they have distinct molecular and circuit underpinnings. Disrupting phosphodiesterases (PDEs), specific G proteins, or BBSome function inhibits escape from 1% O2 due to increased cGMP signaling. A primary source of cGMP is GCY-28, the ortholog of the atrial natriuretic peptide (ANP) receptor. cGMP activates the protein kinase G EGL-4 and enhances neuroendocrine secretion to inhibit acute responses to 1% O2. Triggering a rise in cGMP optogenetically in multiple neurons, including AIA interneurons, rapidly and reversibly inhibits escape from 1% O2. Ca2+ imaging reveals that a 7% to 1% O2 stimulus evokes a Ca2+ decrease in several neurons. Defects in mitochondrial complex I (MCI) and mitochondrial complex I (MCIII), which lead to persistently high reactive oxygen species (ROS), abrogate acute hypoxia responses. In particular, repressing the expression of isp-1, which encodes the iron sulfur protein of MCIII, inhibits escape from 1% O2 without affecting responses to 21% O2. Both genetic and pharmacological up-regulation of mitochondrial ROS increase cGMP levels, which contribute to the reduced hypoxia responses. Our results implicate ROS and precise regulation of intracellular cGMP in the modulation of acute responses to hypoxia by C. elegans.

Cholecystokinin Octapeptide Promotes ANP Secretion through Activation of NOX4-PGC-1α-PPARα/PPARγ Signaling in Isolated Beating Rat Atria.

Atrial natriuretic peptide (ANP), a canonical cardiac hormone, is mainly secreted from atrial myocytes and is involved in the regulation of body fluid, blood pressure homeostasis, and antioxidants. Cholecystokinin (CCK) is also found in cardiomyocytes as a novel cardiac hormone and induces multiple cardiovascular regulations. However, the direct role of CCK on the atrial mechanical dynamics and ANP secretion is unclear. The current study was to investigate the effect of CCK octapeptide (CCK-8) on the regulation of atrial dynamics and ANP secretion. Experiments were performed in isolated perfused beating rat atria. ANP was measured using radioimmunoassay. The levels of hydrogen peroxide (H2O2) and arachidonic acid (AA) were determined using ELISA Kits. The levels of relative proteins and mRNA were detected by Western blot and RT-qPCR. The results showed that sulfated CCK-8 (CCK-8s) rather than desulfated CCK-8 increased the levels of phosphorylated cytosolic phospholipase A2 and AA release through activation of CCK receptors. This led to the upregulation of NADPH oxidase 4 (NOX4) expression levels and H2O2 production and played a negative inotropic effect on atrial mechanical dynamics via activation of ATP-sensitive potassium channels and large-conductance calcium-activated potassium channels. In addition, CCK-8s-induced NOX4 subsequently upregulated peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) expression levels through activation of p38 mitogen-activated protein kinase as well as the serine/threonine kinase signaling, ultimately promoting the secretion of ANP via activation of PPARα and PPARγ. In the presence of the ANP receptor inhibitor, the CCK-8-induced increase of AA release, H2O2 production, and the upregulation of NOX4 and CAT expressions was augmented but the SOD expression induced by CCK-8s was repealed. These findings indicate that CCK-8s promotes the secretion of ANP through activation of NOX4–PGC-1α–PPARα/PPARγ signaling, in which ANP is involved in resistance for NOX4 expression and ROS production and regulation of SOD expression.

Angiotensin II As A Natural Suppressor On Cardiac Natriuretic Peptide System: Molecular Insights And Novel Therapeutic Design

<h3>Introduction</h3> Therapeutic strategies harnessing both renin-angiotensin system (RAS) and natriuretic peptide system (NPS) mediated effects, such as Sacubitril/Valsartan, has been proven to be promising in treating human heart failure (HF). However, molecular understanding of the interaction between RAS and NPS remains to be fully elucidated. While angiotensin II (ANGII), the central RAS hormone, is thought to interact with NPS at multiple levels, whether and how it may influence the actions of particulate guanylyl cyclase A (pGC-A), the only functional receptor for both atrial and b-type natriuretic peptide (ANP and BNP), has not been investigated. <h3>Hypothesis</h3> We hypothesize that ANGII naturally suppresses pGC-A and the inhibition of this crosstalk would be a novel therapeutic strategy to combat cardiovascular disease (CVD) of which RAS hyperactivation is a hallmark feature. <h3>Methods</h3> Plasma ANP, BNP, cGMP, and ANGII were measured in 128 healthy humans to define the balance between ANGII and NPS. cGMP responses to acute infusion of ANP alone and in the presence of ANGII was characterized in normal rats. The molecular mechanisms including involvement of ANGII type I receptor (AT1R) and its downstream target protein kinase C (PKC) were investigated in HEK293 cell overexpressing pGC-A and together with AT1R. CRRL-58, an innovative dual-functional peptide was designed to activate pGC-A and inhibit PKC, and tested for cGMP generation in HEK293 cells. <h3>Results</h3> In healthy human, plasma cGMP was positively associated with ANP or BNP only in low (≤ 4.5 pg/mL) but not those with high (> 4.5 pg/mL) ANGII levels (see Figure). Infusion of ANP (300 pmol/kg/min) in normal rats increased plasma and urinary cGMP, however ANP mediated cGMP generation was reduced in the presence of ANGII (50 pmol/kg/min). Notably, the suppressive effect of ANGII on pGC-A was recapitulated in HEK293 cell overexpressing both pGC-A and AT1R, but not in HEK293 cell overexpressing pGC-A alone. Meanwhile, we found PKC, a well-established downstream target of AT1R, was a key mediator for this observed crosstalk, as the suppression effect of ANGII was largely ablated by Go6983, a pan PKC inhibitor. Notably, CRRL-58 had superior potency in cGMP generation compared to the currently best-in-class ANP-analog, MANP, in vitro. <h3>Conclusions</h3> Our human and experimental data demonstrate that ANGII is a natural suppressor of pGC-A activation via AT1R and PKC signaling, but not via pGC-A per se. Moreover, we report for the first time that CRRL-58, an innovative bioengineered peptide that activates pGC-A receptor while inhibiting PKC signaling, potently generates cGMP. Together, our study provides new insights into the interaction between RAS and NPS, and highlights a novel and mechanism-based therapeutic avenue for treating HF and other CVDs.

Atrial Natriuretic Peptide and the Epithelial Sodium Channel Contribute to Spinal Cord Injury-Induced Polyuria in Mice.

Polyuria is found in patients with spinal cord injury (SCI). However, the underlying cellular and molecular mechanism is unknown. Here, we show that mice had elevated urine for 7 days after T10 contusion. Using multi-photon confocal microscopy, we performed intra-vital imaging experiments to evaluate water reabsorption in kidney tubules by examining fluorescent intensity in the lumen of the distal tubule from live mice. The data show that SCI significantly reduced the concentrating function of kidney tubules. The reduced water reabsorption appears to be mediated by atrial natriuretic peptide (ANP) because SCI increased the expression levels of both ANP and natriuretic peptide receptor A (NPR-A) in the kidney cortex. Our patch-clamp single-channel recordings from split-open distal tubules show that SCI decreased the activity of the epithelial sodium channel (ENaC). Western blot combined with confocal microscopy data show that the levels of 70 kD γ-ENaC, which is an active isoform because of proteolytic cleavage, were significantly reduced in distal tubule principal cells. An NPR-A inhibitor (A71915) given intravenously eliminated the effects of SCI on ENaC and polyuria. These data together with previous studies suggest that SCI causes polyuria, probably by reducing ENaC activity through elevating ANP and NPR-A. Further investigation of the signal transduction pathways may provide useful information for discovering an efficient drug to treat SCI-induced polyuria.

Edema in childhood nephrotic syndrome: possible genes–hormones interplay

BackgroundThe role of atrial natriuretic peptide (ANP) in edema formation in idiopathic nephrotic syndrome (INS) was studied before with conflicting results reported; however, the possible contribution of genes regulating ANP expression and receptors was never explored. MethodsOne hundred children (60 with active INS and 40 in remission) were studied for plasma atrial natriuretic peptide (ANP), urinary sodium, ANP gene A2843G and ScaI polymorphisms, and natriuretic peptide receptor clearance C (-55) A polymorphism. For comparative purposes, 20 healthy controls were studied for ANP levels. ResultsANP was higher in active compared to remission patients (p<0.001). ANP in the healthy control group was significantly lower than the ANP level of active INS (during edema) group (p=0.009) but did not show significant differences when compared to ANP levels of either active INS group after resolution of edema or remission group (p= 0.42 and 0.56, respectively). Urinary sodium levels in edematous patients were significantly lower while ANP levels were significantly higher during edema than after resolution (p< 0.001 for both). Genotypes’ frequencies of studied polymorphisms did not differ between active and remission groups. Patients with the A1A1 genotype of ScaI polymorphism had higher ANP levels compared to other genotypes (p =0.01). ConclusionsDuring edema, ANP levels are elevated in INS children however this increment is not associated with natriuresis suggesting a blunted renal response to ANP. Polymorphisms of genes regulating ANP levels and receptors don’t seem to be implicated in edema formation except for the A1A1 genotype of ScaI polymorphism however, its possible role needs further evaluation.

Modulation of atrial natriuretic peptide receptors in ovarian folliculogenesis

Specific receptors for atrial natriuretic peptide (ANP) located in intra-ovarian tissues are suggested to be involved in ovarian functions such as oocyte maturation and follicle development. However, the characteristics and modulation of its receptor in relation to ovarian folliculogenesis are not well defined. This study examined the properties of ANP receptors in the ovary using quantitative receptor autoradiography. In the pig ovary, the highest binding sites for 125I-ANP(1-28) were localized in the granulosa cell layer of the follicles as well as cumulus oophorous. The binding sites for 125I-ANP(1-28) on theca layer of the ovarian follicles were mainly localized in the external layer, but none was observed in the internal layer. Specific binding of 125I-ANP(1-28) was not found clearly in atretic follicles. In the corpus luteum, the binding site was not observed. Analysis of the competitive inhibition of the binding of 125I-ANP(1-28) to the granulosa and theca externa layers in various preovulatory follicles by increasing concentrations of unlabeled ANP(1-28) was consistent with a single high affinity for 125I-ANP(1-28). The maximal binding capacities of 125I-ANP(1-28) in granulosa layer were significantly increased in proportion to the development of ovarian follicles. However, no significant difference of binding capacities of 125I-ANP(1-28) was observed in theca externa layer. The binding affinities of 125I-ANP(1-28) in granulosa and theca externa layers were not different from each other. Especially, the correlation between specific binding of 125I-ANP(1-28) and follicle diameter. A significant correlation was revealed between specific binding of 125I-ANP(1-28) and follicle diameter (R = 0.88, p &lt; 0.0001) in granulosa layer, however, less relationship was detected in theca externa layer (R = 0.50, p &lt; 0.0001). Therefore, these results indicate that the biological ANP receptors exist in granulosa and the theca externa layers of the pig ovary, and suggest that the ANP receptors in granulosa layer may be related to the regulatory function of the ovarian follicullogenesis including oocyte maturation.

Research Progress of ANP, NPRA, and Cx43 in Gastric Cancer

The occurrence and development of gastric cancer are regulated by many factors and result from the joint action of many factors. Studies have shown that ANP, NPRA, and Cx43 play a vital role in the proliferation and migration of gastric cancer. This article reviews the relationship between Atrial natriuretic peptide (ANP), Atrial natriuretic peptide receptor A (NPRA), and Connexin43 (Cx43) with the occurrence and development of gastric cancer. The review aims to provide an effective reference value for scientific research and clinical treatment.

Inhibition of endogenous ouabain by atrial natriuretic peptide is a guanylyl cyclase independent effect.

Endogenous ouabain (EO) and atrial natriuretic peptide (ANP) are important in regulation of sodium and fluid balance. There is indirect evidence that ANP may be involved in the regulation of endogenous cardenolides. H295R are human adrenocortical cells known to release EO. Cells were treated with ANP at physiologic concentrations or vehicle (0.1% DMSO), with or without guanylyl cyclase inhibitor 1,2,4 oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Cyclic guanosine monophosphate (cGMP), the intracellular second messenger of ANP, was measured by a chemiluminescent immunoassay and EO was measured by radioimmunoassay of C18 extracted samples. EO secretion is inhibited by ANP treatment, with the most prolonged inhibition (90 min vs ≤ 60 min) occurring at physiologic ANP concentrations (50 pg/mL). Inhibition of guanylyl cyclase with ODQ, also reduces EO secretion. The inhibitory effects on EO release in response to cotreatment with ANP and ODQ appeared to be additive. ANP inhibits basal EO secretion, and it is unlikely that this is mediated through ANP-A or ANP-B receptors (the most common natriuretic peptide receptors) or their cGMP second messenger; the underlying mechanisms involved are not revealed in the current studies. The role of ANP in the control of EO synthesis and secretion in vivo requires further investigation.

Short stature is progressive in patients with heterozygous NPR2 mutations

Background NPR2 encodes atrial natriuretic peptide receptor B (ANPRB), a regulator of skeletal growth. Biallelic loss-of-function mutations in NPR2 result in acromesomelic dysplasia Maroteaux type (AMDM; OMIM 602875), while heterozygous mutations may account for 2% to 6% of idiopathic short stature (ISS). Objective Describe the physical proportions and growth characteristics of an extended family with novel NPR2 mutations including members with AMDM, ISS, or normal stature. Design and participants We performed whole exome sequencing in 2 healthy parents and 2 children with AMDM. Detailed genotyping and phenotyping were performed on members of a multigenerational family in an academic medical center. We expressed mutant proteins in mammalian cells and characterized expression and function. Results The sisters with AMDM were compound heterozygotes for missense mutations in the NPR2 gene, a novel p.P93S (maternal) and the previously reported p.R989L (paternal). Both mutant ANPRB proteins were normally expressed in HEK293T cells and exhibited dominant negative effects on wild-type ANPRB catalytic activity. Heterozygous relatives had proportionate short stature (height z-scores -2.06 ± 0.97, median ± SD) compared with their wild-type siblings (-1.37 ± 0.59). Height z-scores progressively and significantly decreased as NPR2-heterozygous children matured, while remaining constant in their wild-type siblings. Conclusions Biallelic NPR2 mutations cause severe skeletal dysplasia (AMDM), whereas heterozygous mutations lead to a subtler phenotype characterized by progressive short stature with by increasing loss of height potential with age.

Heart-Microcirculation Connection: Effects of ANP (Atrial Natriuretic Peptide) on Pericytes Participate in the Acute and Chronic Regulation of Arterial Blood Pressure.

Cardiac ANP (atrial natriuretic peptide) moderates arterial blood pressure. The mechanisms mediating its hypotensive effects are complex and involve inhibition of the renin-angiotensin-aldosterone system, increased natriuresis, endothelial permeability, and vasodilatation. The contribution of the direct vasodilating effects of ANP to blood pressure homeostasis is controversial because variable levels of the ANP receptor, GC-A (guanylyl cyclase-A), are expressed among vascular beds. Here, we show that ANP stimulates GC-A/cyclic GMP signaling in cultured microvascular pericytes and thereby the phosphorylation of the regulatory subunit of myosin phosphatase 1 by cGMP-dependent protein kinase I. Moreover, ANP prevents the calcium and contractile responses of pericytes to endothelin-1 as well as microvascular constrictions. In mice with conditional inactivation (knock-out) of GC-A in microcirculatory pericytes, such vasodilating effects of ANP on precapillary arterioles and capillaries were fully abolished. Concordantly, these mice have increased blood pressure despite preserved renal excretory function. Furthermore, acute intravascular volume expansion, which caused release of cardiac ANP, did not affect blood pressure of control mice but provoked hypertensive reactions in pericyte GC-A knock-out littermates. We conclude that GC-A/cGMP-dependent modulation of pericytes and microcirculatory tone contributes to the acute and chronic moderation of arterial blood pressure by ANP. Graphic Abstract A graphic abstract is available for this article.

Atrial natriuretic peptide (ANP): A novel mechanism for reducing ethanol consumption and seeking behaviors in female alcohol preferring (P) rats

Atrial Naturietic Peptide (ANP) is a neuropeptide that regulates function of the hypothalamic-pituitary-adrenal (HPA) axis, immune and neuroimmune system, and epigenetic factors. Research has indicated that ANP may mediate alcohol intake, withdrawal, and craving like behaviors. ANP receptors are present in the mesocorticolimbic (MCL) reward pathway of the brain, which includes the nucleus accumbens (Acb) and the ventral tegmental area (VTA). The objectives of the present study were to examine the effects of ANP microinjected into Acb subregions (Shell (Sh), Core (Co), ventral to AcbSh) on operant ethanol (EtOH) self-administration and into posterior VTA (pVTA) on EtOH-seeking behavior of female alcohol-preferring (P) rats. In the first experiment, ANP (0, 10 μg, or 100 μg) was microinjected into subregions of the Acb to determine its effects on EtOH self-administration. In the second experiment, ANP was microinjected into pVTA to determine its effects on Pavlovian Spontaneous Recovery (PSR) of responding, a measure of context-induced EtOH-seeking behavior. Administration of ANP directly into the AcbSh significantly reduced EtOH self-administration compared to vehicle, whereas ANP into the AcbCo or areas directly ventral to the AcbSh did not alter responding for EtOH. Microinjection of ANP into the pVTA significantly reduced responding on the EtOH-associated lever during the PSR test. The data indicate that activation of ANP systems in the (a) AcbSh can inhibit EtOH intake, and (b) in the pVTA can inhibit EtOH-seeking behavior. The results suggest that manipulations of the ANP system could be a potential target for pharmacotherapeutic intervention to treat alcohol use disorder. Supported in part by AA07462, AA07611, AA10717, AA10721, AA013522, AA019366, AA020908, AA022287, and AA024612.

Short Stature is Progressive in Patients with Heterozygous NPR2 Mutations.

NPR2 encodes atrial natriuretic peptide receptor B (ANPRB), a regulator of skeletal growth. Biallelic loss-of-function mutations in NPR2 result in acromesomelic dysplasia Maroteaux type (AMDM; OMIM 602875), while heterozygous mutations may account for 2% to 6% of idiopathic short stature (ISS). Describe the physical proportions and growth characteristics of an extended family with novel NPR2 mutations including members with AMDM, ISS, or normal stature. We performed whole exome sequencing in 2 healthy parents and 2 children with AMDM. Detailed genotyping and phenotyping were performed on members of a multigenerational family in an academic medical center. We expressed mutant proteins in mammalian cells and characterized expression and function. The sisters with AMDM were compound heterozygotes for missense mutations in the NPR2 gene, a novel p.P93S (maternal) and the previously reported p.R989L (paternal). Both mutant ANPRB proteins were normally expressed in HEK293T cells and exhibited dominant negative effects on wild-type ANPRB catalytic activity. Heterozygous relatives had proportionate short stature (height z-scores -2.06 ± 0.97, median ± SD) compared with their wild-type siblings (-1.37 ± 0.59). Height z-scores progressively and significantly decreased as NPR2-heterozygous children matured, while remaining constant in their wild-type siblings. Biallelic NPR2 mutations cause severe skeletal dysplasia (AMDM), whereas heterozygous mutations lead to a subtler phenotype characterized by progressive short stature with by increasing loss of height potential with age.

Microarray analysis of human abdominal aortic aneurysm (AAA) detected altered gene expression profiles including H19

Abstract AAA is often a life-threatening disease with poorly understood pathogenesis. We examined gene expression profiles between AAA and normal aorta specimens by cDNA microarray analysis. AAA wall specimens from 5 patients with AAA and grossly normal aortic walls from 3 transplant donors were employed in this study. Total RNA was extracted from each specimen, RT into cDNA, and labeled with phosphorus α-32P. cDNA probes were then hybridized onto human cardiovascular microarray and analyzed by densitometry. Quantitative differences of some genes were further explored by SYBR green-mediated qRT-PCR analysis. Pairwise comparisons of both microarray and qRT-PCR results were made by Student t-test. Most of the 588 genes studied had similar expression among AAA specimens and control aortas, however, 25 genes were upregulated and 26 downregulated. Expression of MMP-9, TIMP3, collagen 1A1 (COL1A1), COL6A3, COL15A1, decorin, MCP 1, Apo E, Apo D, H19 and others was increased. Expression of COL4A4, biglycan, caveolin 3, galectin 1, LDL receptor-related protein 1, extracellular SOD 3, ANP receptor A precursor and others was decreased. Most qRT-PCR results agreed well with those from microarray analysis, with few exceptions. A number of genes that have been previously postulated to participate in AAA pathogenesis, have been upregulated or their expression has been altered. We also revealed some genes that have not been yet studied in human AAA. Of note, H19, one of the most highly up-regulated transcripts in two mouse aneurysm models, was also significantly upregulated in human AAA. These results indicate that many genes involved in different cellular functions might contribute to the pathogenesis of AAA. Supported in part by grant RO1 HL64340 from NIH.

Guanylyl Cyclase A/cGMP Signaling Slows Hidden, Age- and Acoustic Trauma-Induced Hearing Loss.

In the inner ear, cyclic guanosine monophosphate (cGMP) signaling has been described as facilitating otoprotection, which was previously observed through elevated cGMP levels achieved by phosphodiesterase 5 inhibition. However, to date, the upstream guanylyl cyclase (GC) subtype eliciting cGMP production is unknown. Here, we show that mice with a genetic disruption of the gene encoding the cGMP generator GC-A, the receptor for atrial and B-type natriuretic peptides, display a greater vulnerability of hair cells to hidden hearing loss and noise- and age-dependent hearing loss. This vulnerability was associated with GC-A expression in spiral ganglia and outer hair cells (OHCs) but not in inner hair cells (IHCs). GC-A knockout mice exhibited elevated hearing thresholds, most pronounced for the detection of high-frequency tones. Deficits in OHC input–output functions in high-frequency regions were already present in young GC-A-deficient mice, with no signs of an accelerated progression of age-related hearing loss or higher vulnerability to acoustic trauma. OHCs in these frequency regions in young GC-A knockout mice exhibited diminished levels of KCNQ4 expression, which is the dominant K+ channel in OHCs, and decreased activation of poly (ADP-ribose) polymerase-1, an enzyme involved in DNA repair. Further, GC-A knockout mice had IHC synapse impairments and reduced amplitudes of auditory brainstem responses that progressed with age and with acoustic trauma, in contrast to OHCs, when compared to GC-A wild-type littermates. We conclude that GC-A/cGMP-dependent signaling pathways have otoprotective functions and GC-A gene disruption differentially contributes to hair-cell damage in a healthy, aged, or injured system. Thus, augmentation of natriuretic peptide GC-A signaling likely has potential to overcome hidden and noise-induced hearing loss, as well as presbycusis.