Human Natriuretic Peptide Research Articles

Abstract 070: Deletion Of A Non-coding Genomic Segment Orthologous To The Human Rs1173771 Haplotype Region Attenuates Hypertension In Dahl Salt-sensitive Rats

Most SNPs associated by GWAS with blood pressure (BP) phenotypes are located in noncoding regions of DNA. Investigating the physiological effects of these SNPs and their underlying mechanisms will advance our understanding of how genetic and epigenetic mechanisms regulate BP. The BP-associated SNP rs1173771 is in linkage disequilibrium (LD) with 10 other SNPs (r 2 >0.80) forming a haplotype spanning 17.5 kb of noncoding DNA. We explored the effects of the rs1173771 LD orthologous region on BP on the genetic background of Dahl salt-sensitive (SS) rats and the physiological and molecular mechanisms involved. A ~29.5 kb noncoding segment on rat chromosome 5 orthologous to the human rs1173771 LD region was identified using LiftOver. The model SS-rs1173771LD -/- was generated using CRISPR-Cas9 to delete this region in SS rats. BP was not significantly different between SS-rs1173771LD -/- rats and wildtype (WT) littermates on a 0.4% NaCl diet. After 14 days of a 4% NaCl diet, 24-hour mean arterial pressure (MAP) and systolic blood pressure (SBP) of SS-rs1173771LD -/- male rats were significantly lower compared with WT (149.1 ± 2.7 vs 155.9 ± 2.5 mmHg for MAP and 169.6 ± 4.3 vs 179.0 ± 3.0 mmHg for SBP). No difference in diastolic blood pressure was observed. No significant difference of BP was observed between genotypes in females. The transcription start sites of human natriuretic peptide receptor 3 (NPR3) and rat Npr3 are located ~129-kbp and ~80-kbp from the human rs1173771 LD region and the rat orthologous region, respectively. RNA-seq indicated that Npr3 expression was upregulated in the mesenteric artery in SS-rs1173771LD -/- rats. Vasodilation of mesenteric arteries in response to C-type natriuretic peptide was significantly enhanced in SS-rs1173771LD -/- male rats compared with WT littermates. A selective NPR-C antagonist abolished vasodilation in both groups, suggesting the vasorelaxation was NPR-C dependent. In conclusion, deletion of the rs1173771 LD orthologous region increased mesenteric artery vasorelaxation and attenuated salt-induced hypertension in male SS rats. Our findings provided evidence that evolutionarily conserved noncoding DNA regions located far from protein-coding genes can influence BP in vivo.

The natriuretic peptide receptor agonist osteocrin disperses Pseudomonas aeruginosa biofilm

Biofilms are highly tolerant to antimicrobials and host immune defense, enabling pathogens to thrive in hostile environments. The diversity of microbial biofilm infections requires alternative and complex treatment strategies. In a previous work we demonstrated that the human Atrial Natriuretic Peptide (hANP) displays a strong anti-biofilm activity toward Pseudomonas aeruginosa and that the binding of hANP by the AmiC protein supports this effect. This AmiC sensor has been identified as an analog of the human natriuretic peptide receptor subtype C (h-NPRC). In the present study, we evaluated the anti-biofilm activity of the h-NPRC agonist, osteocrin (OSTN), a hormone that displays a strong affinity for the AmiC sensor at least in vitro. Using molecular docking, we identified a pocket in the AmiC sensor that OSTN reproducibly docks into, suggesting that OSTN might possess an anti-biofilm activity as well as hANP. This hypothesis was validated since we observed that OSTN dispersed established biofilm of P. aeruginosa PA14 strain at the same concentrations as hANP. However, the OSTN dispersal effect is less marked than that observed for the hANP (−61% versus −73%). We demonstrated that the co-exposure of P. aeruginosa preformed biofilm to hANP and OSTN induced a biofilm dispersion with a similar effect to that observed with hANP alone suggesting a similar mechanism of action of these two peptides. This was confirmed by the observation that OSTN anti-biofilm activity requires the activation of the complex composed by the sensor AmiC and the regulator AmiR of the ami pathway. Using a panel of both P. aeruginosa laboratory reference strains and clinical isolates, we observed that the OSTN capacity to disperse established biofilms is highly variable from one strain to another. Taken together, these results show that similarly to the hANP hormone, OSTN has a strong potential to be used as a tool to disperse P. aeruginosa biofilms.

Natriuretic peptides appeared after their receptors in vertebrates

BackgroundIn mammals, the natriuretic system contains three natriuretic peptides, NPPA, NPPB and NPPC, that bind to three transmembrane receptors, NPR1, NPR2 and NPR3. The natriuretic peptides are known only in vertebrates. In contrast, the receptors have orthologs in all the animal taxa and in plants. However, in non-vertebrates, these receptors do not have natriuretic properties, and most of their ligands are unknown. How was the interaction of the NP receptors and the NP established in vertebrates? Do natriuretic peptides have orthologs in non-vertebrates? If so, what was the function of the interaction? How did that function change? If not, are the NP homologous to ancestral NPR ligands? Or did the receptor’s binding pocket completely change during evolution?MethodsIn the present study, we tried to determine if the pairs of natriuretic receptors and their ligands come from an ancestral pair, or if the interaction only appeared in vertebrates. Alignments, modeling, docking, research of positive selection, and motif research were performed in order to answer this question.ResultsWe discovered that the binding pocket of the natriuretic peptide receptors was completely remodeled in mammals. We found several peptides in non vertebrates that could be related to human natriuretic peptides, but a set of clues, as well as modeling and docking analysis, suggest that the natriuretic peptides undoubtedly appeared later than their receptors during animal evolution. We suggest here that natriuretic peptide receptors in non vertebrates bind to other ligands.ConclusionsThe present study further support that vertebrate natriuretic peptides appeared after their receptors in the tree of life. We suggest the existence of peptides that resemble natriuretic peptides in non-vertebrate species, that might be the result of convergent evolution.

Regulation of Monospecies and Mixed Biofilms Formation of Skin Staphylococcus aureus and Cutibacterium acnes by Human Natriuretic Peptides.

Staphylococcus aureus and Cutibacterium acnes are common representatives of the human skin microbiome. However, when these bacteria are organized in biofilm, they could be involved in several skin disorders such as acne or psoriasis. They inhabit in hollows of hair follicles and skin glands, where they form biofilms. There, they are continuously exposed to human hormones, including human natriuretic peptides (NUPs). We first observed that the atrial natriuretic peptide (ANP) and the C-type natriuretic peptide (CNP) have a strong effect S. aureus and C. acnes biofilm formation on the skin. These effects are significantly dependent on the aero-anaerobic conditions and temperature. We also show that both ANP and CNP increased competitive advantages of C. acnes toward S. aureus in mixed biofilm. Because of their temperature-dependent effects, NUPs appear to act as a thermostat, allowing the skin to modulate bacterial development in normal and inflammatory conditions. This is an important step toward understanding how human neuroendocrine systems can regulate the cutaneous microbial community and should be important for applications in fundamental sciences, medicine, dermatology, and cosmetology.

Natriuretic Peptides in Post-mortem Brain Tissue and Cerebrospinal Fluid of Non-demented Humans and Alzheimer's Disease Patients.

Animal studies suggest the involvement of natriuretic peptides (NP) in several brain functions that are known to be disturbed during Alzheimer’s disease (AD). However, it remains unclear whether such findings extend to humans. In this study, we aimed to: (1) map the gene expression and localization of NP and their receptors (NPR) in human post-mortem brain tissue; (2) compare the relative amounts of NP and NPR between the brain tissue of AD patients and non-demented controls, and (3) compare the relative amounts of NP between the cerebrospinal fluid (CSF) of AD patients and non-demented controls. Using the publicly available Allen Human Brain Atlas dataset, we mapped the gene expression of NP and NPR in healthy humans. Using immunohistochemistry, we visualized the localization of NP and NPR in the frontal cortex of AD patients (n = 10, mean age 85.8 ± 6.2 years) and non-demented controls (mean age = 80.2 ± 9.1 years). Using Western blotting and ELISA, we quantified the relative amounts of NP and NPR in the brain tissue and CSF of these AD patients and non-demented controls. Our results showed that NP and NPR genes were ubiquitously expressed throughout the brain in healthy humans. NP and NPR were present in various cellular structures including in neurons, astrocyte-like structures, and cerebral vessels in both AD patients and non-demented controls. Furthermore, we found higher amounts of NPR type-A in the brain of AD patients (p = 0.045) and lower amounts of NP type-B in the CSF of AD patients (p = 0.029). In conclusion, this study shows the abundance of NP and NPR in the brain of humans suggesting involvement of NP in various brain functions. In addition, our findings suggest alterations of NP levels in the brain of AD patients. The role of NP in the development and progression of AD remains to be elucidated.

Regulation of Formation of Monospecies and Binary Biofilms by Human Skin Microbiota Components, Staphylococcus epidermidis and Staphylococcus aureus, by Human Natriuretic Peptides

Human natriuretic peptides (NUPs) types A and C were shown have different effects on the growth of monospecies and binary biofilms of human skin commensal microorganisms Staphylococcus epidermidis and Staphylococcus aureus. The effect of natriuretic peptides depended on cultivation conditions: at 37°С growth of monospecies biofilms formed by S. epidermidis and S. aureus was stimulated and inhibited, respectively, resulting in changed values of the biofilm average thickness and biomass in presence of NUPs. At 33°С effects of NUPs reversed: growth of S. epidermidis monospecies biofilms was inhibited. In binary biofilms at 37°С, NUPs were able to increase the competitiveness of S. epidermidis against S. aureus. NUPs affected predominantly biofilms and, to a lesser degree, planktonic cultures. This phenomenon makes it possible to consider NUPs as the molecules able to regulate the interactions between the human organism and skin microbiota.

Discovery and in vivo effects of novel human natriuretic peptide receptor A (NPR-A) agonists with improved activity for rat NPR-A

Natriuretic peptide receptor A (NPR-A) agonists were evaluated in vivo by optimizing the structure of quinazoline derivatives to improve agonistic activity for rat NPR-A. A 1,4-Cis-aminocyclohexylurea moiety at 4-position and hydroxy group of d-alaninol at 2-position on the quinazoline ring were found to be important factors in improving rat NPR-A activity. We identified potent quinazoline and pyrido[2,3-d]pyrimidine derivatives against rat NPR-A, with double-digit nanomolar EC50 values. The in vivo results showed that compound 56b administered at 1.0 mg/kg/min significantly increased plasma cGMP concentration and urine volume in rats. We discovered novel potent NPR-A agonists that showed agonistic effects similar to those of atrial natriuretic peptide.

Sustained Activation of Guanylate Cyclase-A with TDT, a Natriuretic Peptide Derivative, Exhibits Cardiorenal Protection in Dahl Salt-Sensitive Hypertensive Rats.

Heart failure often presents with prognosis-relevant impaired renal function. To investigate whether the chronic activation of guanylate cyclase-A (GC-A) protects both heart and kidney, we examined the effects of TDT, a neprilysin (NEP)-resistant natriuretic peptide (NP) derivative, on cardiac and renal dysfunction in Dahl salt-sensitive hypertensive (DS) rats. Pretreatment with NEP or NEP inhibitor did not influence GC-A activation by TDT both in vitro and in vivo, resulting in a long-acting profile of TDT compared with native human atrial NP (hANP). The repeated administration of TDT to DS rats suppressed the progress of cardiac hypertrophy, systolic/diastolic dysfunction, and proteinuria in a dose-dependent manner. Compared with vehicle and hANP, salt diet-induced podocyte injury was reduced by TDT, as analyzed by urinary podocalyxin concentration, renal expression of nephrin mRNA, and glomerular expression of desmin protein. Since glomerular TRPC6 plays detrimental roles in podocyte homeostasis, we examined the renal expression of TRPC6 in DS rats and found that salt diet upregulated the expression of TRPC6. Importantly, TRPC6 induction was significantly decreased in TDT-treated rats, compared with vehicle and hANP. Consistently, in primary-culture podocytes from DS rats, TDT inhibited ATP-induced calcium influx, similar to TRPC inhibitor SKF96365. Finally, TDT-mediated protection of podocytes was abolished by protein kinase G inhibitor KT5823. In conclusion, TDT treatment attenuated heart and kidney dysfunction, accompanied by podocyte protection through inhibition of TRPC6. Thus, long-acting NPs could be a new avenue for treatment of heart failure.

Assessment of Human Natriuretic Peptides (B), Human N-Terminal Pro-BNP and Nor-epinephrine as Neurohumoral Markers in Sleep Disordered Breathing among Heart Failure Patients in Upper Egypt

Objective: The purposes of this study are to: (1) Measure neurohumoral activation in heart failure patients with and without Sleep Disordered Breathing; (2) Assessment of neurohumoral markers with the severity of sleep apnea and severity of heart failure.Patients and methods: In this case report study, we studied 100 patients with heart failure (64 male, 36 female). All patients underwent echocardiography and a full night-attended polysomnography, in addition to neurohumoral evaluation.Results: Group (1) sleep Disordered Breathing (SDB) had significant increase in the plasma concentration level of BNP (591.50 ± 165.75 vs. 298.33 ± 86.63 pg/ml, P=0.001*), NT-proBNP (1750.05 ± 773.15 vs. 686.98 ± 377.88 pg/ml, P=0.001*) and nor epinephrine (NE) (616.12 ± 139.57 vs. 203.80 ± 64.30 pg/ml, P=0.001*) when compared with No-SDB. A significant increase in plasma level of NT-proBNP and nor-epinephrine (NE) in OSA was observed when compared with central sleep apnea (CSA). Increased neurohumoral markers with different severity of apnea hypopnea index (AHI). Moreover, a significant increase was observed in neurohumoral markers with increased severity of left ventricular ejection fraction (LVEF). Based on echocardiographic etiology of heart failure, patients with dilated cardiomyopathy had a significant increase in plasma level of BNP and NT-pro BNP. On the other hand, plasma concentration level of norepinephrine (NE) was significantly increased in patients with hypertensive heart disease.Conclusion: Heart failure patients with sleep disordered breathing were associated with higher levels of neurohumoral activation. Moreover N-TproBNP (<300m pg/ml) and nor epinephrine (NE)<300 pg/ml were predictors of OSA among heart failure.

Clinical Aspects of C-Type Natriuretic Peptide on the Cardiovascular System

C-type natriuretic peptide (CNP) is one of the three most important members of the human natriuretic peptide family, sharing with them a highly conserved 17-aminoacid ring structure, essential to elicit its biological actions by binding to its specific receptor NPR-B. CNP acts in a paracrine or autocrine way and it is cleared from plasma circulation by the NPR-C receptor. This is one of the reasons why its plasma levels are usually low.

Pseudomonas aeruginosa Expresses a Functional Human Natriuretic Peptide Receptor Ortholog: Involvement in Biofilm Formation.

ABSTRACTConsiderable evidence exists that bacteria detect eukaryotic communication molecules and modify their virulence accordingly. In previous studies, it has been demonstrated that the increasingly antibiotic-resistant pathogen Pseudomonas aeruginosa can detect the human hormones brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) at micromolar concentrations. In response, the bacterium modifies its behavior to adapt to the host physiology, increasing its overall virulence. The possibility of identifying the bacterial sensor for these hormones and interfering with this sensing mechanism offers an exciting opportunity to directly affect the infection process. Here, we show that BNP and CNP strongly decrease P. aeruginosa biofilm formation. Isatin, an antagonist of human natriuretic peptide receptors (NPR), prevents this effect. Furthermore, the human NPR-C receptor agonist cANF4-23 mimics the effects of natriuretic peptides on P. aeruginosa, while sANP, the NPR-A receptor agonist, appears to be weakly active. We show in silico that NPR-C, a preferential CNP receptor, and the P. aeruginosa protein AmiC have similar three-dimensional (3D) structures and that both CNP and isatin bind to AmiC. We demonstrate that CNP acts as an AmiC agonist, enhancing the expression of the ami operon in P. aeruginosa. Binding of CNP and NPR-C agonists to AmiC was confirmed by microscale thermophoresis. Finally, using an amiC mutant strain, we demonstrated that AmiC is essential for CNP effects on biofilm formation. In conclusion, the AmiC bacterial sensor possesses structural and pharmacological profiles similar to those of the human NPR-C receptor and appears to be a bacterial receptor for human hormones that enables P. aeruginosa to modulate biofilm expression.

Diabetic hypertensive patients have a blood pressure to wake up and arterial stiffness significantly higher than those not diabetic at similar ages

Human natriuretic peptide clearance receptor is induced by insulin and is associated with metabolic parameters Marica Bordicchia, Monica Ceresiani, Antonella Pocognoli, Marianna Pavani, Giovanni Muzzonigro, Massimo Polito, Martin Wabitsch, Valentina Cannone, John C. Burnett, Jr., Paolo Dess i-Fulgheri, Riccardo Sarzani. Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Department of Medicine and Health Sciences Research, College of Medicine, Mayo Clinic, Rochester, MN, United States; Department of Urology, UNIVPM, Ancona, Italy; Division of Pediatric Endocrinology and Diabetes, Interdisciplinary Obesity Unit, Department of Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany; Internal Medicine and Geriatrics, ‘‘Hypertension Excellence Centre’’ of the European Society of Hypertension, Department of Clinical and Molecular Sciences, UNIVPM, Italian National Research Centre on Aging ‘‘U.Sestilli’’, IRCCS-INRCA, Ancona

Human natriuretic peptide clearance receptor is induced by insulin and is associated with metabolic parameters

Human natriuretic peptide clearance receptor is induced by insulin and is associated with metabolic parameters

Ularitide for the treatment of acute decompensated heart failure: from preclinical to clinical studies.

The short- and long-term morbidity and mortality in acute heart failure is still unacceptably high. There is an unmet need for new therapy options with new drugs with a new mode of action. One of the drugs currently in clinical testing in Phase III is ularitide, which is the chemically synthesized form of the human natriuretic peptide urodilatin. Urodilatin is produced in humans by differential processing of pro-atrial natriuretic peptide in distal renal tubule cells. Physiologically, urodilatin appears to be the natriuretic peptide involved in sodium homeostasis. Ularitide exerts its pharmacological actions such as vasodilation, diuresis, and natriuresis through the natriuretic peptide receptor/particulate guanylate cyclase/cyclic guanosine monophosphate pathway. In animal models of heart failure as well as Phase I and II clinical studies in heart failure patients, ularitide demonstrated beneficial effects such as symptom relief and vasodilation, while still preserving renal function. Subsequently, the pivotal acute decompensated heart failure (ADHF) Phase III study, called TRUE-AHF, was started with the objectives to evaluate the effects of ularitide infusion on the clinical status and cardiovascular mortality of patients with ADHF compared with placebo. This review summarizes preclinical and clinical data supporting the potential use of ularitide in the treatment of ADHF.

The effects of fusion structure on the expression and bioactivity of human brain natriuretic peptide (BNP) albumin fusion proteins.

Human brain natriuretic peptide (BNP) is utilized in the treatment of acute decompensated congestive heart failure. However, BNP has limited clinical use owing to its rapid clearance and the need for continuous intravenous infusion. Thus, we generated human serum albumin (HSA)-BNP fusion constructs to produce long-acting fusion proteins in Pichia pastoris. Four fusion proteins, BNP-HSA, (BNP)2-HSA, (BNP)4-HSA, and HSA-(BNP)2, were constructed, with different numbers of BNP molecules and fusion orientations. BNP-HSA was most abundantly expressed in Pichia pastoris and (BNP)4-HSA had the lowest yield, probably because of the high copy number of BNP. Western blot analysis confirmed the immunogenicity of both BNP and HSA for the four fusion proteins. A cGMP activity assay was used to measure the ability of fusion proteins to stimulate intracellular cGMP expression. Results showed that the fusion protein HSA-(BNP)2 activated human natriuretic peptide receptor A (hNPR-A) with potency similar to that of BNP, despite using a 10-fold higher dosage than BNP. The other three fusion proteins (BNP-HSA, (BNP)2-HSA, and (BNP)4-HSA), only slightly increased NPR-A activity. In addition, fusion with HSA successfully prolonged BNP bioactivity, stimulating intracellular cGMP expression over 24 h. In conclusion, HSA-(BNP)2, with two BNP molecules fused at the C-terminus of HSA, has the highest and most prolonged BNP bioactivity in activating human NPR-A.

Chimeric natriuretic peptide ACNP stimulates both natriuretic peptide receptors, the NPRA and NPRB

Here, we investigated the receptor profile of the newly designed natriuretic peptide (NP) ACNP consisting of the N- and C-terminus of human ANP and the ring structure of CNP, its potency/efficacy in stimulating cGMP generation in primary cells, and its stability towards peptidase activity. ACNP stimulated both human natriuretic peptide receptors (NPRs), NPRA and NPRB, as potent as their native ligands in receptor transfected cells. Consequently, ACNP was more efficient in generating cGMP compared to ANP, BNP, and CNP, in primary cells expressing both NPRs. All NPs have been similarly degraded by neprilysin, except the neprilysin-resistant BNP. However, ACNP was fastest degraded in serum, while CNP was most stable. Congruently, CNP but not ACNP reduced blood pressure most significantly after acute peptide infusion in normotensive mice. Our data identify ACNP as the first compound being able to stimulate both natriuretic receptors with similar potency and efficacy as their respective ligands.

Does hypoxemia have an impact on the cardiac release and circulating concentrations of natriuretic peptides in humans in vivo?

A large number of experimental studies have suggested that hypoxia may be a potent stimulus for the myocardial synthesis and release of A-type natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) [1]. However, these studies have evaluated either the effect of hypoxia on ANP and/or BNP production in isolated cardiomyocytes [2,3], isolated perfused hearts [4,5], or animals [5,6], or on the circulating concentrations of ANP, BNP, and/or N-terminal pro-BNP (NT-proBNP) but not on the cardiac release of these peptides in humans [7–9].

The therapeutic potential of synthetic human atrial natriuretic peptide in nephrotic syndrome: a randomized controlled trial

BackgroundIn nephrotic syndrome, the combination of furosemide and albumin infusion is a standard regimen to treat systemic edema. The efficacy of synthetic human atrial natriuretic peptide (hANP) for nephrotic syndrome to ameliorate the systemic edema and retain renal functions has not been fully demonstrated.Trial designWe conducted a prospective, randomized, controlled, open-label clinical trial. Patients were randomly assigned by a stratified biased coin design.MethodsA total of 12 patients with nephrotic syndrome between the ages of 20 to 79 years were enrolled and randomly assigned to either the conventional (CON) group treated with furosemide and albumin, and hANP group, in which carperitide was administered in addition to the conventional therapies. The primary end points were: (1) the differences in serum creatinine levels, and (2) the reduction of total dosage of furosemide and albumin by the treatments of hANP. Secondary end points were body weight, systolic blood pressure, heart rate, serum protein, albumin, and urinary protein excretion.ResultsA total of 13 patients were enrolled, and one patient was excluded due to severe pneumonia. In both hANP (n = 7) and CON (n = 5) groups, body weight was reduced after 2-week treatments. Serum creatinine levels at follow-up significantly increased compared with baseline. The increase in serum creatinine levels (Δ serum creatinine) was smaller in the hANP group compared with the CON group (P = 0.31). The serum uric acid, serum urea nitrogen, and urinary protein excretion were reduced in the hANP group, and increased in the CON group, though these differences were not statistically significant. The usage of hANP significantly reduced the total dosage of furosemide (P < 0.05) during the treatment periods. No adverse effects were observed.ConclusionsThe concomitant use of synthetic hANP with conventional therapies is beneficial for reducing the dosage of loop diuretics, and the elevation of serum creatinine and uric acid may be avoided.

Cardiac natriuretic peptides act via p38 MAPK to induce the brown fat thermogenic program in mouse and human adipocytes

The ability of mammals to resist body fat accumulation is linked to their ability to expand the number and activity of "brown adipocytes" within white fat depots. Activation of β-adrenergic receptors (β-ARs) can induce a functional "brown-like" adipocyte phenotype. As cardiac natriuretic peptides (NPs) and β-AR agonists are similarly potent at stimulating lipolysis in human adipocytes, we investigated whether NPs could induce human and mouse adipocytes to acquire brown adipocyte features, including a capacity for thermogenic energy expenditure mediated by uncoupling protein 1 (UCP1). In human adipocytes, atrial NP (ANP) and ventricular NP (BNP) activated PPARγ coactivator-1α (PGC-1α) and UCP1 expression, induced mitochondriogenesis, and increased uncoupled and total respiration. At low concentrations, ANP and β-AR agonists additively enhanced expression of brown fat and mitochondrial markers in a p38 MAPK-dependent manner. Mice exposed to cold temperatures had increased levels of circulating NPs as well as higher expression of NP signaling receptor and lower expression of the NP clearance receptor (Nprc) in brown adipose tissue (BAT) and white adipose tissue (WAT). NPR-C(-/-) mice had markedly smaller WAT and BAT depots but higher expression of thermogenic genes such as Ucp1. Infusion of BNP into mice robustly increased Ucp1 and Pgc-1α expression in WAT and BAT, with corresponding elevation of respiration and energy expenditure. These results suggest that NPs promote "browning" of white adipocytes to increase energy expenditure, defining the heart as a central regulator of adipose tissue biology.

Transactivation in Drosophila of human enhancers by human transcription factors involved in congenital heart diseases

Background: The human transcription factors (TFs) GATA4, NKX2.5 and TBX5 form part of the core network necessary to build a human heart and are involved in Congenital Heart Diseases (CHDs). The human natriuretic peptide precursor A (NPPA) and α-myosin heavy chain 6 (MYH6) genes are downstream effectors involved in cardiogenesis that have been demonstrated to be in vitro targets of such TFs. Results: To study the interactions between these human TFs and their target enhancers in vivo, we overexpressed them in the whole Drosophila cardiac tube using the UAS/GAL4 system. We observed that all three TFs up-regulate their natural target enhancers in Drosophila and cause developmental defects when overexpressed in eyes and wings. Conclusions: A strong potential of the present model might be the development of combinatorial and mutational assays to study the interactions between human TFs and their natural target promoters, which are not easily undertaken in tissue culture cells because of the variability in transfection efficiency, especially when multiple constructs are used. Thus, this novel system could be used to determine in vivo the genetic nature of the human mutant forms of these TFs, setting up a powerful tool to unravel the molecular genetic mechanisms that lead to CHDs. Developmental Dynamics 241:190–199, 2012. © 2011 Wiley Periodicals, Inc.Key findingsThe mammalian transcription factors GATA4, Nkx2.5 and TBX5 are able to transactivate the Nppa and Myh6 human enhancers in Drosophila embryos.The endogenous Drosophila homologs of GATA4, Nkx2.5 and TBX5 are not transactivated by GATA4, Nkx2.5 or TBX5, ruling out a possible endogenous regulatory circuit.Overexpression in the mesoderm of GATA4, Nkx2.5 or TBX5 is lethal and overexpression in eyes and wings causes reduced organs.