Downregulation of salusins alleviates hypertrophic cardiomyopathy via attenuating oxidative stress and autophagy.

INTRODUCTION: Salusins, which are translated from the alternatively spliced mRNA of torsin family 2 member A (TOR2A), play a vital role in regulation of various cardiovascular diseases. However, it remains unclear precisely regarding their roles in hypertrophic cardiomyopathy (HCM). Therefore, this study was conducted to explore therapeutic effect and the underlying mechanisms of salusins on HCM. MATERIAL AND METHODS: In vivo experiments, Sprague-Dawley rats were used to induce HCM model by angiotensin (Ang) II infusion for 4 weeks. The rats were randomly divided into four groups, namely, Saline + Control shRNA (n = 7), Ang II + Control shRNA (n = 8), Saline + TOR2A shRNA (n = 7), and Ang II + TOR2A shRNA groups (n = 8). After HCM induction, doppler echocardiography is recommended to evaluate heart function. In vitro experiments, primary neonatal rat cardiomyocytes (NRCMs) and cardiac fibroblasts (NRCFs) were obtained from newborn rats, and were treated with Ang II (10-6 M) for 24 h. RESULTS: After treatment with Ang II, levels of salusin-α and salusin-ß were elevated in serum and cardiac tissues of rats and in the neonatal rat cardiomyocytes and cardiac fibroblasts. Downregulation of salusins alleviated the Ang II-induced cardiac hypertrophy by suppressing the increased atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and beta-myosin heavy chain (ß-MHC) and cardiac fibrosis by blocking collagen I, collagen III and transforming growth factor-beta (TGF-ß), and it also attenuated oxidative stress by suppressing the increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels and reversing the decreased superoxide dismutase (SOD) activity and autophagy by inhibiting the increased microtubule-associated protein light chain 3B (LC3B), Beclin1, autophagy related gene (Atg) 3 and Atg5 in the cardiac tissues of Ang II-infused rats and in the Ang II-treated NRCMs. CONCLUSIONS: All these findings suggest that the levels of salusins were elevated in the HCM, and targeting of salusins contributes to alleviation of cardiac hypertrophy and fibrosis probably via attenuating oxidative stress and autophagy. Accordingly, targeting of salusins may be a strategy for HCM therapy.

Investigating the association of Angiotensin II Type I Receptor A1166C Polymorphism with Breast Cancer Risk in the Pakistani Population.

The polymorphisms of the Renin-Angiotensin System are related to many disorders like diabetes, cardiovascular disease, and different types of cancer. Among all the polymorphisms related to AGTR1, A1166C has been associated with several disorders, including cardiovascular diseases and breast cancer. This study was conducted to discover the association of AGTR1 polymorphism (A1166C) Renin-Angiotensin and its effect on the development and progression of breast cancer in the Pakistani population. One hundred forty participants, including seventy diagnosed breast cancer patients and seventy healthy individuals, were included in this study and genotyped with an allele-specific polymerase chain reaction. The most frequent genotype in healthy participants and breast cancer patients was CC. An insignificant (p value>0.05) risk of breast cancer was found with A1166C polymorphism in codominant (CC vs. AA OR=1.200 [0.256-5.631] and AC vs. AA 0.941 [OR=0.223-3.976]), dominant (OR=1.00 [0.240-4.167]), recessive (OR=1.230 [0.593-2.552]) and additive models (OR=1.028 [0.533-1.983]) of general population genotypes. Nonetheless, when the AA genotype was considered a reference group, a significant association was found between AC and CC genotypes and invasive ductal and ductal carcinoma development in breast cancer patients. In conclusion, this study demonstrated no significant association between AGTR1 (A1166C) polymorphism and breast cancer risk.

Synaptotagmin-7 mediates cardiac hypertrophy by targeting autophagy.

Sustained cardiac hypertrophy damages the heart and weakens cardiac function, often leading to heart failure and even death. Pathological cardiac hypertrophy has become a central therapeutic target for many heart diseases including heart failure. However, the underlying mechanisms of cardiac hypertrophy, especially the involvement of autophagy program, are still ill-understood. Synaptotagmin-7 (Syt7), a multifunctional and high-affinity calcium sensor, plays a pivotal role in asynchronous neurotransmitter release, synaptic facilitation, and vesicle pool regulation during synaptic transmission. However, little is known about whether Syt7 is expressed in the myocardium and involved in the pathogenesis of heart diseases. Here we showed that Syt7 was significantly upregulated in Ang II-treated hearts and cardiomyocytes. Homozygous syt7 knockout (syt7-/-) mice exhibited significantly attenuated cardiac hypertrophy and fibrosis and improved cardiac function. We further found that Syt7 exerted a pro-hypertrophic effect by suppressing the autophagy process. In exploring the upstream mechanisms, microRNA (miR)-93 was identified to participate in the regulation of Syt7 expression. miR-93 protected hearts against Ang II-induced hypertrophy through targeting Syt7-autophagy pathway. In summary, our data reveal a new cardiac hypertrophy regulator and a novel hypertrophy regulating model composed of miR-93, Syt7 and autophagy program. These molecules may serve as potential therapeutic targets in the treatment of cardiac hypertrophy and heart failure.

Angiotensinogen, Angiotensin-Converting Enzyme, and Chymase Gene Polymorphisms as Biomarkers for Basal Cell Carcinoma Susceptibility.

INTRODUCTION: The intake of angiotensin-converting enzyme (ACE) inhibitors and specific antagonists of angiotensin II receptors, widely used as antihypertensive drugs, significantly reduces the risk of developing basal cell carcinoma (BCC), highlighting the possible tumorigenic role of angiotensin II (AngII). We present here the investigated genetic association between the development of BCC and functional DNA polymorphisms M235T, I/D, and A1903G in the genes of angiotensinogen (AGT), angiotensin-converting enzyme (ACE), and chymase (CMA1), which mediate AngII production levels. METHODS: DNA samples of 203 unrelated Greeks were studied, including 100 patients with BCC and 103 matched healthy controls. RESULTS: The MT genotype of the AGT-M235T polymorphism was significantly more prevalent in the patient group (78.0%) versus the healthy control group (28.3%; p < 0.001). The DD genotype of the ACE-I/D polymorphism was also increased in BCC patients (72.8%) compared to controls (46.2%; p = 0.001). The heterozygous AG genotype of CMA1-A1903G was significantly more frequent in the BCC group (86%) than in the healthy controls (50.5%; p < 0.001). CONCLUSIONS: The MT, DD, and AG genotypes of the AGT- M235T, ACE-I/D, and CMA1-A1903G polymorphisms, respectively, were significantly increased in frequency within the group of cancer patients compared to the healthy controls. All three genotypes correspond to increased enzyme levels or activity and result in increased levels of AngII; therefore, they may be potentially utilized as reliable biomarkers associated with an individual's increased risk for BCC development.

SIRT6 is an epigenetic repressor of thoracic aortic aneurysms via inhibiting inflammation and senescence.

Thoracic aortic aneurysms (TAAs) develop asymptomatically and are characterized by dilatation of the aorta. This is considered a life-threating vascular disease due to the risk of aortic rupture and without effective treatments. The current understanding of the pathogenesis of TAA is still limited, especially for sporadic TAAs without known genetic mutation. Sirtuin 6 (SIRT6) expression was significantly decreased in the tunica media of sporadic human TAA tissues. Genetic knockout of Sirt6 in mouse vascular smooth muscle cells accelerated TAA formation and rupture, reduced survival, and increased vascular inflammation and senescence after angiotensin II infusion. Transcriptome analysis identified interleukin (IL)-1ß as a pivotal target of SIRT6, and increased IL-1ß levels correlated with vascular inflammation and senescence in human and mouse TAA samples. Chromatin immunoprecipitation revealed that SIRT6 bound to the Il1b promoter to repress expression partly by reducing the H3K9 and H3K56 acetylation. Genetic knockout of Il1b or pharmacological inhibition of IL-1ß signaling with the receptor antagonist anakinra rescued Sirt6 deficiency mediated aggravation of vascular inflammation, senescence, TAA formation and survival in mice. The findings reveal that SIRT6 protects against TAA by epigenetically inhibiting vascular inflammation and senescence, providing insight into potential epigenetic strategies for TAA treatment.

Blood pressure-independent renoprotective effects of small interference RNA targeting liver angiotensinogen in experimental diabetes.

BACKGROUND AND PURPOSE: Small interfering RNA (siRNA) targeting liver angiotensinogen lowers blood pressure, but its effects in hypertensive diabetes are unknown. EXPERIMENTAL APPROACH: To address this, TGR (mRen2)27 rats (angiotensin II-dependent hypertension model) were made diabetic with streptozotocin over 18 weeks and treated with either vehicle, angiotensinogen siRNA, the AT1 antagonist valsartan, the ACE inhibitor captopril, valsartan + siRNA or valsartan + captopril for the final 3 weeks. Mean arterial pressure (MAP) was measured via radiotelemetry. KEY RESULTS: MAP before treatment was 153 ± 2 mmHg. Diabetes resulted in albuminuria, accompanied by glomerulosclerosis and podocyte effacement, without a change in glomerular filtration rate. All treatments lowered MAP and cardiac hypertrophy, and the largest drop in MAP was observed with siRNA + valsartan. Treatment with siRNA lowered circulating angiotensinogen by >99%, and the lowest circulating angiotensin II and aldosterone levels occurred in the dual treatment groups. Angiotensinogen siRNA did not affect renal angiotensinogen mRNA expression, confirming its liver-specificity. Furthermore, only siRNA with or without valsartan lowered renal angiotensin I. All treatments lowered renal angiotensin II and the reduction was largest (>95%) in the siRNA + valsartan group. All treatments identically lowered albuminuria, whereas only siRNA with or without valsartan restored podocyte foot processes and reduced glomerulosclerosis. CONCLUSION AND IMPLICATIONS: Angiotensinogen siRNA exerts renoprotection in diabetic TGR (mRen2)27 rats and this relies, at least in part, on the suppression of renal angiotensin II formation from liver-derived angiotensinogen. Clinical trials should now address whether this is also beneficial in human diabetic kidney disease.

Association Between a High Gene Expression Variant of Chymase and Increased Risk for Basal Cell Carcinoma.

BACKGROUND/AIM: Previous studies have associated certain variations in genes encoding factors of renin-angiotensin system (RAS), indirectly leading to higher angiotensin II (AngII) levels, with greater risk for basal cell carcinoma (BCC) development. Chymase (CMA1) is the main regulator of the RAS-independent AngII generation pathway and numerous studies have shown its oncogenic potential in several cancer types including BCC. In this study, we investigated the possible association between BCC pathogenesis and the functional DNA polymorphism A1903G (rs1800875) that affects expression of the CMA1 gene. PATIENTS AND METHODS: We genotyped 199 DNA samples, isolated from 100 BCC patients and 99 age, sex, and ethnicity-matched healthy controls for the CMA1 A1903G polymorphism. Genotyping was performed with PCR amplification, followed by MboI enzyme digestion and agarose gel electrophoresis of the resulted DNA fragments. RESULTS: The variant G allele that possibly increases CMA1 gene expression was not detected at a significantly different frequency between the groups of BCC patients and healthy controls. However, the AG heterozygous genotype was significantly increased in BCC patients compared with controls (p<0.001). CONCLUSION: The high expression CMA1 G allele carriers have an increased risk for BCC and elevated levels of chymase in the skin may have a carcinogenic effect.

[Gly14]-Humanin inhibits an angiotensin II-induced vascular smooth muscle cell phenotypic switch via ameliorating intracellular oxidative stress.

Angiotensin II (AngII) is involved in the pathogenesis of hypertensive artery remodeling by inducing a phenotypic switch in vascular smooth muscle cells [Gly14]-Humanin (HNG), a humanin analogue, exerts potent cytoprotective effects both in vitro and in vivo. This study aimed to investigate the effects of HNG on an AngII-induced phenotypic switch in VSMCs and the potential mechanisms underlying these effects. The roles of [Gly14]-Humanin in AngII-stimulated VSMCs proliferation and migration was detected by CCK-8 assay, Cell cycle analysis, wound healing assay, trsnswell assay and western blot. The mechanism by which [Gly14]-Humanin regulates VSMC phenotypic switch was determined by intracellular oxidative stress detection, transcriptomic analysis and qRT-PCR. The results showed that HNG inhibited AngII-induced VSMC proliferation and migration and maintained a stable VSMC contractile phenotype. In addition, HNG reduced the level of AngII-induced oxidative stress in vascular smooth muscle cells. This process could be accomplished by inhibiting nicotinamide adenine dinucleotide phosphate oxidase activity. In conclusion, the results suggested that HNG ameliorated intracellular oxidative stress by inhibiting NAD(P)H oxidase activity, thereby suppressing the AngII-induced VSMC phenotype switch. Thus, HNG is a potential drug to ameliorate artery remodeling in hypertension.

Angiotensin II Mediates Cardiomyocyte Hypertrophy in Atrial Cardiomyopathy via Epigenetic Transcriptional Regulation.

Aims: European Heart Rhythm Association established an expert consensus to define, characterize, and classify atrial cardiomyopathy into four subgroups based on their histopathological features. The predominant pathological feature of classes I and III is the hypertrophy of atrial cardiomyocytes. Here, we aim to investigate the mechanism of epigenetic transcriptional regulation of cardiomyocyte hypertrophy in atrial cardiomyopathy. Methods and Results: Compared with that of sinus rhythm control individuals, the myocardium of patients with atrial fibrillation exhibited increased levels of angiotensin II (AngII), chromatin-bound myocyte enhancer factor 2 (MEF2), acetylated histone H4 (H4ac), and H3K27ac; upregulation of hypertrophy-related genes; and decreased levels of histone deacetylase (HDAC) 4 and HDAC5 bound to the promoters of hypertrophy-related genes. Furthermore, incubation of atrial cardiomyocytes with AngII increased their cross-sectional area and improved the expression of hypertrophy-related genes. AngII also promoted the phosphorylation of HDAC4 and HDAC5 and induced their nuclear export. RNA sequencing analyses revealed that AngII significantly upregulated genes associated with cardiac hypertrophy. Chromatin immunoprecipitation showed that this correlated with increased levels of chromatin-bound MEF2, H4ac, and H3K27ac and decreased HDAC4 and HDAC5 enrichment in the promoters of hypertrophy-related genes. Moreover, these AngII-induced prohypertrophic effects could be partially reverted by treatment with the AngII receptor blocker losartan. Conclusions: AngII had a prohypertrophic effect on atrial cardiomyopathy which was epigenetic-dependent. Patients with atrial fibrillation manifest an increased susceptibility to hypertrophy and exhibit epigenetic characteristics that are permissive for the transcription of hypertrophy-related genes. AngII induces histone acetylation via the cytoplasmic-nuclear shuttling of HDACs, which constitutes a novel mechanism of atrial hypertrophy regulation and might provide a promising therapeutic strategy for atrial cardiomyopathy.

An intersegmental single-cell profile reveals aortic heterogeneity and identifies a novel Malat1+ vascular smooth muscle subtype involved in abdominal aortic aneurysm formation.

The developmental origin, anatomical location, and other factors contribute to aortic heterogeneity in a physiological state. On this basis, vascular diseases occur at different ratios based on position specificity, even with the same risk factor. However, the continuous intersegmental aortic profile has been rarely reported at the single-cell level. To reveal aortic heterogeneity, we identified 15 cell subtypes from five continuous aortic segments by marker genes and functional definitions. The EC1 subtype highly expressed Vcam1 and Scarb2 genes in the aortic arch, which were reported to be associated with atherosclerosis. The newly identified Fbn1+ fibroblasts were found highly expressed in thoracic segments. More importantly, vascular smooth muscle cells (VSMCs) demonstrated a novel composition in which VSMC 4 marked with the gene Malat1 were mainly distributed in the abdominal segment. Malat1 knockout reduced MMPs and inflammatory factor production induced by Ang II in smooth muscle cells, and the Malat1 inhibitor exerted preventive, inhibitory, and reversing effects on AngII-induced abdominal aortic aneurysm (AAA) in vivo revealed by a series of animal experiments. Single-cell analysis of AngII-induced AAA tissues treated with or without the inhibitor further clarified the key role of Malat1+VSMC in the occurrence and progression of AAA. In summary, segmental gene expression and cell subtype features in normal aorta associated with different vascular diseases might provide potential therapeutic targets.

Roles of Angiotensin III in the brain and periphery.

Angiotensin (Ang) III, a biologically active peptide of the renin angiotensin system (RAS) is predominantly known for its central effects on blood pressure. Our understanding of the RAS has evolved from the simplified, classical RAS, a hormonal system regulating blood pressure to a complex system affecting numerous biological processes. Ang II, the main RAS peptide has been widely studied, and its deleterious effects when overexpressed is well-documented. However, other components of the RAS such as Ang III are not well studied. This review examines the molecular and biological actions of Ang III and provides insight into Ang III's potential role in metabolic diseases.

Angiotensin II and AT1a Receptors in the Proximal Tubules of the Kidney: New Roles in Blood Pressure Control and Hypertension.

Contrary to public perception, hypertension remains one of the most important public health problems in the United States, affecting 46% of adults with increased risk for heart attack, stroke, and kidney diseases. The mechanisms underlying poorly controlled hypertension remain incompletely understood. Recent development in the Cre/LoxP approach to study gain or loss of function of a particular gene has significantly helped advance our new insights into the role of proximal tubule angiotensin II (Ang II) and its AT1 (AT1a) receptors in basal blood pressure control and the development of Ang II-induced hypertension. This novel approach has provided us and others with an important tool to generate novel mouse models with proximal tubule-specific loss (deletion) or gain of the function (overexpression). The objective of this invited review article is to review and discuss recent findings using novel genetically modifying proximal tubule-specific mouse models. These new studies have consistently demonstrated that deletion of AT1 (AT1a) receptors or its direct downstream target Na+/H+ exchanger 3 (NHE3) selectively in the proximal tubules of the kidney lowers basal blood pressure, increases the pressure-natriuresis response, and induces natriuretic responses, whereas overexpression of an intracellular Ang II fusion protein or AT1 (AT1a) receptors selectively in the proximal tubules increases proximal tubule Na+ reabsorption, impairs the pressure-natriuresis response, and elevates blood pressure. Furthermore, the development of Ang II-induced hypertension by systemic Ang II infusion or by proximal tubule-specific overexpression of an intracellular Ang II fusion protein was attenuated in mutant mice with proximal tubule-specific deletion of AT1 (AT1a) receptors or NHE3. Thus, these recent studies provide evidence for and new insights into the important roles of intratubular Ang II via AT1 (AT1a) receptors and NHE3 in the proximal tubules in maintaining basal blood pressure homeostasis and the development of Ang II-induced hypertension.

Evolutionary information helps understand distinctive features of the angiotensin II receptors AT1 and AT2 in amniota.

In vertebrates, the octopeptide angiotensin II (AngII) is an important in vivo regulator of the cardiovascular system. It acts mainly through two G protein-coupled receptors, AT1 and AT2. To better understand distinctive features of these receptors, we carried out a phylogenetic analysis that revealed a mirror evolution of AT1 and AT2, each one split into two clades, separating fish from terrestrial receptors. It also revealed that hallmark mutations occurred at, or near, the sodium binding site in both AT1 and AT2. Electrostatics computations and molecular dynamics simulations support maintained sodium binding to human AT1 with slow ingress from the extracellular side and an electrostatic component of the binding free energy around -3kT, to be compared to around -2kT for human AT2 and the δ opioid receptor. Comparison of the sodium binding modes in wild type and mutated AT1 and AT2 from humans and eels indicates that the allosteric control by sodium in both AT1 and AT2 evolved during the transition from fish to amniota. The unusual S7.46N mutation in AT1 is mirrored by a L3.36M mutation in AT2. In the presence of sodium, the N7.46 pattern in amniota AT1 stabilizes the inward orientation of N3.35 in the apo receptor, which should contribute to efficient N3.35 driven biased signaling. The M3.36 pattern in amniota AT2 favours the outward orientation of N3.35 and the receptor promiscuity. Both mutations have physiological consequences for the regulation of the renin-angiotensin system.

Evaluation of insertion/deletion (I/D) polymorphisms of ACE gene and circulating levels of angiotensin II in congenital anomalies of the kidney and urinary tract.

BACKGROUND: Congenital Anomalies of the Kidney and the Urinary Tract (CAKUT) are defined as a heterogeneous group of anomalies that resulted from defects in kidney and urinary tract embryogenesis. CAKUT have a complex etiology. Genetic, epigenetic and environmental factors have been investigated in this context. Angiotensin II is a potent vasoconstrictor and exerts an important role in kidney embryogenesis. The angiotensin-converting enzyme (ACE) converts Angiotensin I into Angiotensin II (Ang II) and ACE gene has insertion/deletion (I/D) polymorphisms that have been evaluated in several nephropathies. This study aimed to evaluate whether the I/D polymorphisms of ACE gene and the circulating levels of Ang II are associated with any CAKUT phenotype or CAKUT in general. METHODS AND RESULTS: Our study was performed with 225 pediatric patients diagnosed with CAKUT and 210 age-and-sex matched healthy controls. ACE I/D alleles were analysed by real-time polymerase chain reaction (RT-PCR). The distribution of ACE I/D polymorphisms were compared between CAKUT patients and healthy controls, as well between ureteropelvic junction obstruction (UPJO), vesicoureteral reflux (VUR), multicystic dysplastic kidney (MCDK) phenotypes and control group. No statistical association was detected between ACE I/D polymorphism and CAKUT and UPJO, VUR, and MCDK phenotypes. In a subset of 80 CAKUT patients and 80 controls, plasma levels of Ang II were measured. No significant differences were found between CAKUT patients and controls, even in regard to comparisons of UPJO, VUR and MCDK with control group. CONCLUSION: Although CAKUT is a complex disease and the ACE gene may exert a role in kidney embryogenesis, CAKUT was not associated with any ACE I/D polymorphisms nor with differences in plasma levels of Ang II in this Brazilian pediatric population.

Impact of the ACE2 activator xanthenone on tacrolimus nephrotoxicity: Modulation of uric acid/ERK/p38 MAPK and Nrf2/SOD3/GCLC signaling pathways.

AIMS: The calcineurin inhibitor tacrolimus is an effective and widely used immunosuppressant after organ transplantation to reduce graft rejection. However, its nephrotoxic effect could compel the patients to treatment discontinuation. The beneficial effects of angiotensin-converting enzyme 2 (ACE2) on the kidney and other organs have been investigated in several studies, but its role in tacrolimus nephrotoxicity still needs to be elucidated. Our study was designed to investigate effects of the ACE2 activator xanthenone on tacrolimus-induced renal injury. MATERIALS AND METHODS: Male Wistar rats were administered xanthenone (2 mg/kg) concurrently with tacrolimus (1 mg/kg) for 3 weeks, then blood and kidney tissue samples were collected for biochemical and molecular investigations. KEY FINDINGS: Co-administration of xanthenone significantly improved renal functions in tacrolimus-treated rats, where serum creatinine, urea, and uric acid levels were close to those of the normal control. Besides, xanthenone reduced renal angiotensin (ANG) II content, while elevated ANG (1-7). Relative protein expressions of p-ERK/ERK and p-p38 MAPK/p38 MAPK inflammatory signals were downregulated upon xanthenone administration with tacrolimus. In addition, xanthenone reinforced antioxidant defense against tacrolimus by enhancing protein expression of the transcription factor Nrf2 with subsequently increased mRNA expressions of the antioxidants SOD3 and GCLC. SIGNIFICANCE: These protective effects of xanthenone could be attributed to ANG II degradation to ANG (1-7) by ACE2 activation resulting in regulated inflammatory and oxidative responses in the kidney. Therefore, administration of xanthenone along with tacrolimus could be a promising therapeutic strategy to reduce the adverse effects and increase the tolerability to tacrolimus immunosuppressive therapy.

In Vivo Renin Activity Imaging in the Kidney of Progeroid Ercc1 Mutant Mice.

Changes in the renin-angiotensin system, known for its critical role in the regulation of blood pressure and sodium homeostasis, may contribute to aging and age-related diseases. While the renin-angiotensin system is suppressed during aging, little is known about its regulation and activity within tissues. However, this knowledge is required to successively treat or prevent renal disease in the elderly. Ercc1 is involved in important DNA repair pathways, and when mutated causes accelerated aging phenotypes in humans and mice. In this study, we hypothesized that unrepaired DNA damage contributes to accelerated kidney failure. We tested the use of the renin-activatable near-infrared fluorescent probe ReninSense680™ in progeroid Ercc1d/- mice and compared renin activity levels in vivo to wild-type mice. First, we validated the specificity of the probe by detecting increased intrarenal activity after losartan treatment and the virtual absence of fluorescence in renin knock-out mice. Second, age-related kidney pathology, tubular anisokaryosis, glomerulosclerosis and increased apoptosis were confirmed in the kidneys of 24-week-old Ercc1d/- mice, while initial renal development was normal. Next, we examined the in vivo renin activity in these Ercc1d/- mice. Interestingly, increased intrarenal renin activity was detected by ReninSense in Ercc1d/- compared to WT mice, while their plasma renin concentrations were lower. Hence, this study demonstrates that intrarenal RAS activity does not necessarily run in parallel with circulating renin in the aging mouse. In addition, our study supports the use of this probe for longitudinal imaging of altered RAS signaling in aging.

Stearoyl-CoA Desaturase (SCD) Induces Cardiac Dysfunction with Cardiac Lipid Overload and Angiotensin II AT1 Receptor Protein Up-Regulation.

Heart failure is a major cause of death worldwide with insufficient treatment options. In the search for pathomechanisms, we found up-regulation of an enzyme, stearoyl-CoA desaturase 1 (Scd1), in different experimental models of heart failure induced by advanced atherosclerosis, chronic pressure overload, and/or volume overload. Because the pathophysiological role of Scd1/SCD in heart failure is not clear, we investigated the impact of cardiac SCD upregulation through the generation of C57BL/6-Tg(MHCSCD)Sjaa mice with myocardium-specific expression of SCD. Echocardiographic examination showed that 4.9-fold-increased SCD levels triggered cardiac hypertrophy and symptoms of heart failure at an age of eight months. Tg-SCD mice had a significantly reduced left ventricular cardiac ejection fraction of 25.7 ± 2.9% compared to 54.3 ± 4.5% of non-transgenic B6 control mice. Whole-genome gene expression profiling identified up-regulated heart-failure-related genes such as resistin, adiponectin, and fatty acid synthase, and type 1 and 3 collagens. Tg-SCD mice were characterized by cardiac lipid accumulation with 1.6- and 1.7-fold-increased cardiac contents of saturated lipids, palmitate, and stearate, respectively. In contrast, unsaturated lipids were not changed. Together with saturated lipids, apoptosis-enhancing p53 protein contents were elevated. Imaging by autoradiography revealed that the heart-failure-promoting and membrane-spanning angiotensin II AT1 receptor protein of Tg-SCD hearts was significantly up-regulated. In transfected HEK cells, the expression of SCD increased the number of cell-surface angiotensin II AT1 receptor binding sites. In addition, increased AT1 receptor protein levels were detected by fluorescence spectroscopy of fluorescent protein-labeled AT1 receptor-Cerulean. Taken together, we found that SCD promotes cardiac dysfunction with overload of cardiotoxic saturated lipids and up-regulation of the heart-failure-promoting AT1 receptor protein.

Role of Melatonin in Angiotensin and Aging.

The cellular utilization of oxygen leads to the generation of free radicals in organisms. The accumulation of these free radicals contributes significantly to aging and several age-related diseases. Angiotensin II can contribute to DNA damage through oxidative stress by activating the NAD(P)H oxidase pathway, which in turn results in the production of reactive oxygen species. This radical oxygen-containing molecule has been linked to aging and several age-related disorders, including renal damage. Considering the role of angiotensin in aging, melatonin might relieve angiotensin-II-induced stress by enhancing the mitochondrial calcium uptake 1 pathway, which is crucial in preventing the mitochondrial calcium overload that may trigger increased production of reactive oxygen species and oxidative stress. This review highlights the role and importance of melatonin together with angiotensin in aging and age-related diseases.

Interaction between the Renin-Angiotensin System and Enteric Neurotransmission Contributes to Colonic Dysmotility in the TNBS-Induced Model of Colitis.

Angiotensin II (Ang II) regulates colon contraction, acting not only directly on smooth muscle but also indirectly, interfering with myenteric neuromodulation mediated by the activation of AT1 /AT2 receptors. In this article, we aimed to explore which mediators and cells were involved in Ang II-mediated colonic contraction in the TNBS-induced rat model of colitis. The contractile responses to Ang II were evaluated in distinct regions of the colon of control animals or animals with colitis in the absence and presence of different antagonists/inhibitors. Endogenous levels of Ang II in the colon were assessed by ELISA and the number of AT1/AT2 receptors by qPCR. Ang II caused AT1 receptor-mediated colonic contraction that was markedly decreased along the colons of TNBS-induced rats, consistent with reduced AT1 mRNA expression. However, the effect mediated by Ang II is much more intricate, involving (in addition to smooth muscle cells and nerve terminals) ICC and EGC, which communicate by releasing ACh and NO in a complex mechanism that changes colitis, unveiling new therapeutic targets.

Losartan Protects Podocytes against High Glucose-induced Injury by Inhibiting B7-1 Expression.

The role of B7-1 in podocyte injury has received increasing attention. The aim of this study was to investigate whether losartan protects podocytes of patients with diabetic kidney disease (DKD) by regulating B7-1 and the underlying mechanisms. Rats with streptozotocin-induced DKD were treated with losartan for 8 weeks. Biochemical changes in blood and urine were analyzed. Kidneys were isolated for electron microscopy, immunofluorescence, real-time quantitative PCR (RT-PCR), and Western blot analysis. Immortalized mouse podocyte cells were cultured in normal or high glucose medium in the presence or absence of losartan for 48 h, and then the cells were collected for immunofluorescence, PCR, Western blotting and monolayer permeability detection. The phosphatidylinositol 3-kinase (PI3K) 110α subunit and angiotensin II type 1 receptor (AT1R) plasmids were transfected into podocytes, respectively, and then Western blotting was performed to assess the expression of B7-1 protein. The results showed that losartan ameliorated podocyte structure and function in the rat model of DKD, and reduced the expression of B7-1 protein. Overexpression of PI3K 110α subunit in podocytes attenuated the inhibitory effect of losartan on B7-1 expression in high glucose-stimulated podocytes. The expression of B7-1 was significantly increased by overexpression of AT1R and significantly reduced by blocking PI3K 110α subunit. We conclude that losartan protects podocytes against high glucose-induced injury by inhibiting AT1R-mediated B7-1 expression. This effect is dependent on the AT1R-PI3K 110α subunit pathway.