Expression of the renin angiotensin system genes in the kidney and heart of ISIAH hypertensive rats

The content of mRNA of renin-angiotensin system (RAS) genes was measured in the kidney and heart of hypertensive ISIAH and normotensive WAG rats using the real-time PCR. A statistically significant decrease in the mRNA level of RAS genes was registered in the kidney of ISIAH rats, including Ren (by 45%), Ace (43%), AT1A (34%), COX-2 (50%). The level of myocardial expression of AT1A decreased by 28% while Ace expression increased by 80%. These results suggest reduction of renal RAS basal activity in the hypertensive ISIAH rats, and therefore this strain of rats may be referred to the group of models of low-renin hypertension. The ISIAH rats were also characterized by a two-fold increase in the connective tissue sodium concentration and also by a small (but statistically significant) increase in plasma sodium concentration (139 ± 0.3 mmol/l versus 136 ± 0.25 mmol/l in WAG rats). These results together with a tendency to a decrease of plasma aldosterone level also support existence of a classical low-renin hypertension in the ISIAH rats. It is suggested that altered function of renal ion channels represents a basis for the development of low renin hypertension in the ISIAH rats. In addition, impairments in renal system of NO synthesis may also contribute to the pathogenesis of arterial hypertension in the ISIAH rats.     

Drugs inhibiting the renin - angiotensin system

There are several approaches for interfering with the renin-angiotensin system. Antibodies against renin angiotensins I and II (AI and AII) have not been consistently successful in the past, probably because of nonspecific effects; however, recent purification of renin now makes this approach more promising. Renin inhibitors include pepstatin and analogs, lipids and phospholipids, and renin-substrate analogs. Pepstatin and analogs are the most potent and specific but they are not orally active. The phospholipids are the most effective in vivo but their specificity is yet to be established. No renin-substrate analogs have been developed that have biologically significant effects. Some of the most potent and specific agents available for interfering with the renin-angiotensin system are the AII-receptor antagonists. While these compounds effectively prevent the actions of AII, they suffer from several severe deficiencies: partial agonist activity, short duration of action, and lack of oral activity. The recent development of angiotensin-converting enzyme ACE) inhibitors that are orally active has provided the greatest degree of clinical success for inhibitors of the renin-angiotensin system and, consequently, the impetus to develop still better compounds. Captopril (SQ 14,225) is the prototype ACE inhibitor, being highly potent and specific with no other demonstrated pharmacological activity. Captopril is effective in all forms of human and animal models of hypertension except mineralocorticoid hypertension, which requires concomitant diuretic therapy. Because ACE is the same enzyme as kininase II, the enzyme that degrades kinins, the possibility exists that kinins are involved in the cardiovascular action of captopril, although this prospect is unlikely.     

DNA sequence adjacent to flagellar genes and evolution of flagellar-phase variation

A variety of factors, including phase variation, are involved in the regulation of flagellin gene expression in Salmonella sp. Flagellar-phase variation refers to the alternate expression of two different flagellin genes, H1 and H2. Site-specific inversion of a DNA segment adjacent to the H2 gene is responsible for switching expression. The segment includes the H2 promoter as well as the hin gene, which is required to mediate the inversion. Sequences in this region have homology with the corresponding sequences adjacent to the H1 flagellin gene in Salmonella sp. and the hag flagellin gene in Escherichia coli. The hin gene has also been shown to be homologous to the gin gene, which is found on bacteriophage Mu. To understand gene expression and the origin of these relationships, we have compared the DNA sequence adjacent to all three flagellin genes. The sequence data suggest a mechanism for the evolution of the hin-H2 locus.     

Differentiation of nephrotensin from the renin angiotensin system.

An investigation of the relationship between nephrotensin and the renin angiotensin system was carred out. Nephrotensin was found in the plasma of rats with renal clip hypertension and with chemically induced kidney damage. There was no demonstrable correlation between presence of nephrotensin and plasma renin activity, and the pressor activity of nephrotensin was not altered by previous immunization of test animals with angiotensin II nor by pretreatment with angiotensin I converting enzyme inhibitor. These results indicate that nephrotensin is different from the components of the renin-angiotensin system.     

The degree of variation in DNA sequence recognition among four Drosophila homeotic proteins.

The homeodomain has been implicated as a major determinant of biological specificity for the homeotic selector (HOM) genes. We compare here the DNA sequence preferences of homeodomains encoded by four of the eight Drosophila HOM proteins. One of the four, Abdominal-B, binds preferentially to a sequence with an unusual 5'-T-T-A-T-3' core, whereas the other three prefer 5'-T-A-A-T-3'. Of these latter three, the Ultrabithorax and Antennapedia homeodomains display indistinguishable preferences outside the core while Deformed differs. Thus, with three distinct binding classes defined by four HOM proteins, differences in individual site recognition may account for some but not all of HOM protein functional specificity. We further show that amino acid residues within the N-terminal arm are responsible for the sequence specificity differences between the Ultrabithorax and Abdominal-B homeodomains. Similarities and differences at the corresponding positions within the N-terminal arms are conserved in the vertebrate Abdominal-B-like HOM proteins, which play critical roles in limb specifications as well as in regional specification along the anterior-posterior axis. This and other patterns of residue conservation suggest that differential DNA sequence recognition may play a role in HOM protein function in a wide range of organisms.     

肾素-血管紧张素系统的新调节分子:ACE2

血管紧张素转化酶（angiotensin—converting enzyme,ACE）为含锌的金属蛋白酶,是肾素-血管紧张素系统（renin—angiotensin system,RAS）重要的调节分子。血管紧张素转化酶2（angiotensin—con—verting enzyme2,ACE2）是迄今发现的唯一的ACE同系物（homologue）,它主要分布于睾丸、肾脏和心脏。ACE2可水解血管紧张素Ⅰ（angiotensinⅠ,AngⅠ）和血管紧张素Ⅱ（angiotensinⅡ,AngⅡ）羧基端的1个氨基酸残基,分别形成Ang1-9和有血管舒张作用的Ang1-7。ACE2的生理病理作用还不甚明了,传统的ACE抑制剂不能抑制ACE2的活性。ACE2在心血管、肾脏系统的作用可能与ACE相反．与ACE共同调节心脏、肾脏等脏器的正常功能。     

Survey of polymorphic sequence variation in the immediate 5' region of human DNA repair genes

Systematic screens have revealed extensive DNA sequence variation existing in the human population. Studies of the role of polymorphic genetic variants in explaining the association of family history with risk of common disease have generally focused on variants predicted to disrupt protein structure and activity. Recent studies have identified genetic variation in the level of expression of many genes, variation that is potentially biologically relevant in explaining individual variation in disease risk. In a survey of data available for 108 DNA repair genes that have been systematically screened for sequence variation, an average of 3.3 SNPs per gene were found to exist at a variant allele frequency of at least 0.02 in the region 2kb upstream from the 5'-untranslated region. One-third of the genes harbored a SNP with an allele frequency of at least 0.02 within a predicted promotor element. These variants are distributed among promoter elements that average 20 elements per gene. The frequency of polymorphic SNPs in CpG islands was 0.8 per gene, while the frequency of SNPs in the 5'-UTR was 0.7 per gene. The recognition of extensive genetic variation with potential to impact levels of gene expression, and thereby exacerbate the impact of amino acid substitution variants on the activity of proteins, increases the complexity of analyses required to explain the molecular genetic basis for the familial contribution to the sporadic incidence of common disease.     

Understanding human DNA sequence variation

Over the past century researchers have identified normal genetic variation and studied that variation in diverse human populations to determine the amounts and distributions of that variation. That information is being used to develop an understanding of the demographic histories of the different populations and the species as a whole, among other studies. With the advent of DNA-based markers in the last quarter century, these studies have accelerated. One of the challenges for the next century is to understand that variation. One component of that understanding will be population genetics. We present here examples of many of the ways these new data can be analyzed from a population perspective using results from our laboratory on multiple individual DNA-based polymorphisms, many clustered in haplotypes, studied in multiple populations representing all major geographic regions of the world. These data support an "out of Africa" hypothesis for human dispersal around the world and begin to refine the understanding of population structures and genetic relationships. We are also developing baseline information against which we can compare findings at different loci to aid in the identification of loci subject, now and in the past, to selection (directional or balancing). We do not yet have a comprehensive understanding of the extensive variation in the human genome, but some of that understanding is coming from population genetics.     

Inflammation,oxidative stress and renin angiotensin system in atherosclerosis

Atherosclerosis is a chronic inflammatory disease associated with cardiovascular dysfunction including myocardial infarction, unstable angina, sudden cardiac death, stroke and peripheral thromboses. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with cardiovascular risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. The impairment of the endothelium associated with cardiovascular risk factors creates an imbalance between vasodilating and vasoconstricting factors, in particular, an increase in angiotensin Ⅱ(Ang Ⅱ) and a decrease in nitric oxide. The renin-angiotensin system(RAS), and its primary mediator Ang Ⅱ, also have a direct influence on the progression of the atherosclerotic process via effects on endothelial function, inflammation, fibrinolytic balance, and plaque stability. Anti-inflammatory agents [statins, secretory phospholipase A2 inhibitor, lipoprotein-associated phospholipase A2 inhibitor, 5-lipoxygenase activating protein, chemokine motif ligand-2, C-C chemokine motif receptor 2 pathway inhibitors, methotrexate, IL-1 pathway inhibitor and RAS inhibitors(angiotensin-converting enzyme inhibitors)], Ang Ⅱ receptor blockers and ranin inhibitors may slow inflammatory processes and disease progression. Several studies in human using anti-inflammatory agents and RAS inhibitors revealed vascular benefits and reduced progression of coronary atherosclerosis in patients with stable angina pectoris; decreased vascular inflammatory markers, improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis. Recent preclinical studies have demonstrated therapeutic efficacy of vitamin D analogs paricalcitol in Apo E-deficient atherosclerotic mice.     

Role of brain renin angiotensin system in neurodegeneration: An update

Renin angiotensin system (RAS) is an endocrine system widely known for its physiological roles in electrolyte homeostasis, body fluid volume regulation and cardiovascular control in peripheral circulation. However, brain RAS is an independent form of RAS expressed locally in the brain, which is known to be involved in brain functions and disorders. There is strong evidence for a major involvement of excessive brain angiotensin converting enzyme (ACE)/Angiotensin II (Ang II)/Angiotensin type-1 receptor (AT-1R) axis in increased activation of oxidative stress, apoptosis and neuroinflammation causing neurodegeneration in several brain disorders. Numerous studies have demonstrated strong neuroprotective effects by blocking AT1R in these brain disorders. Additionally, the angiotensin converting enzyme 2 (ACE2)/Angiotensin (1–7)/Mas receptor (MASR), is another axis of brain RAS which counteracts the damaging effects of ACE/Ang II/AT1R axis on neurons in the brain. Thus, angiotensin II receptor blockers (ARBs) and activation of ACE2/Angiotensin (1–7)/MASR axis may serve as an exciting and novel method for neuroprotection in several neurodegenerative diseases. Here in this review article, we discuss the expression of RAS in the brain and highlight how altered RAS level may cause neurodegeneration. Understanding the pathophysiology of RAS and their links to neurodegeneration has enormous potential to identify potentially effective pharmacological tools to treat neurodegenerative diseases in the brain.     

DNA sequence and haplotype variation in two candidate genes for dilated cardiomyopathy in the turkey Meleagris gallopavo

Determining variation in genes is fundamental to understanding their function in the disease state. Cardiac troponin T (cTnT) and phospholamban (PLN) genes have been implicated in dilated cardiomyopathy (DCM) in human and model species. To investigate the role of these 2 candidate genes in DCM in the turkey Meleagris gallopavo, understanding sequence variants and map position distribution is necessary. To this end, a total of 1854 and 1771 bp of cTnT and PLN gene sequences, respectively, were scanned for single nucleotide polymorphisms (SNPs) in a randomly bred population. A total of 15 SNPs was identified in the cTnT and PLN genomic sequences. Nine haplotypes, 5 in cTnT and 4 in PLN, were identified. Observed heterozygosities (0.02-0.39) in the turkey population were low for both genes. Within each gene, 1 SNP corresponding to a restriction enzyme site was identified and used to develop a PCR-restriction fragment length polymorphism (RFLP) genotyping assay. The PLN gene was genetically mapped to turkey chromosome 2, equivalent to Gallus gallus chromosome 3, and cTnT mapped to a turkey microchromosome. Although limited because of the relatively small sample size of 55 birds, the data from this SNP analysis of PLN and cTnT provide a foundation from which to evaluate the function of cTnT and PLN in the turkey. Information about the distribution of the SNPs and haplotypes will facilitate future association and linkage studies.     

Mitochondrial DNA sequence variation in Greeks.

Mitochondrial DNA (mtDNA) control region sequences were determined in 54 unrelated Greeks, coming from different regions in Greece, for both segments HVR-I and HVR-II. Fifty-two different mtDNA haplotypes were revealed, one of which was shared by three individuals. A very low heterogeneity was found among Greek regions. No one cluster of lineages was specific to individuals coming from a certain region. The average pairwise difference distribution showed a value of 7.599. The data were compared with that for other European or neighbor populations (British, French, Germans, Tuscans, Bulgarians, and Turks). The genetic trees that were constructed revealed homogeneity between Europeans. Median networks revealed that most of the Greek mtDNA haplotypes are clustered to the five known haplogroups and that a number of haplotypes are shared among Greeks and other European and Near Eastern populations.     

Angiotensin III: A physiological relevant peptide of the renin angiotensin system

The renin angiotensin system (RAS) is a peptide hormone system that plays an important role in the pathophysiology of various diseases, including congestive heart failure, hypertension, myocardial infarction, and diabetic nephropathy. This has led researchers to focus extensively on this system, leading to the discovery of various peptides, peptidases, receptors and signal transduction mechanisms intrinsic to the RAS. Angiotensinogen (AGT), angiotensin (Ang) II, Ang III, Ang IV, and Ang-(1–7) are the main biologically active peptides of RAS. However, most of the available studies have focused on Ang II as the likely key peptide from the RAS that directly and indirectly regulates physiological functions leading to pathological conditions. However, data from recent studies suggest that Ang III may produce physiologically relevant effects that are similar to those produced by Ang II. Hence, this review focuses on Ang III and the myriad of physiological effects that it produces in the body.     

肾素-血管紧张素系统与糖尿病心肌病关系的研究进展

糖尿病时,肾素-血管紧张素系统(renin-angiotensin system,RAS)被激活,升高的血管紧张素Ⅱ(Ang Ⅱ)通过细胞表面的AT1受体,刺激心肌成纤维细胞增生及胶原代谢改变,引起心脏结构重塑,导致心肌间质及血管周围纤维化,胶原含量增多和排列紊乱,造成心室肌僵硬而影响舒张功能,出现糖尿病心肌病(diabetic cardiomyopathy,DCM)的临床症状.本文从RAS的主要成分Ang Ⅱ、Ang-(1-7)、Ac-SDKP和血管紧张素受体(ATR)与内皮素、活性氧、转化生长因子-β1、核因子-κB、信号转导系统以及细胞凋亡之间的相互作用,阐述RAS在糖尿病心肌病发生发展中所起的重要作用.     

Effect of oral contraceptives on the renin angiotensin system and renal function

We examined the effect of oral contraceptive (OC) usage on the renin angiotensin system (RAS) in two related experiments. In the first experiment, subjects were 34 healthy, normotensive, premenopausal women, 15 OC users and 19 OC nonusers, mean age 25 +/- 1 yr, ingesting a controlled sodium diet. We assessed arterial pressure, glomerular filtration rate, effective renal plasma flow, renal vascular resistance (RVR), and filtration fraction (FF) using inulin and p-aminohippurate clearance techniques, both at baseline and in response to the ANG II receptor blocker losartan. In the second experiment, in similar subjects, 10 OC users and 10 nonusers, we examined circulating RAS components [angiotensinogen, ANG II, aldosterone, plasma renin activity (PRA), and active renin] in response to incremental lower body negative pressure (LBNP), to determine whether renin secretion is suppressed by OC usage. OC users exhibited elevations in systolic blood pressure, RVR, and FF compared with nonusers, which were partially corrected by losartan. In the LBNP phase of the study, baseline measures of PRA, angiotensinogen, ANG II, and aldosterone were all increased in the OC group compared with the control group. Active renin levels did not differ between groups. Incremental LBNP resulted in increased circulating levels of RAS components in both groups. We conclude that the RAS is activated in women using OCs. There was no evidence that decreases in renin secretion result in normalization of the RAS as a whole.     

Repeated sequence DNA relationships in four cereal genomes

The effect of DNA fragment size on the extent of hybridisation that occurs between repeated sequence DNAs from oats, barley, wheat and rye has been investigated. The extent of hybridisation is very dependent on fragment size, at least over the range of 200 to 1000 nucleotides. This is because only a fraction of each fragment forms duplex DNA during renaturation. From these results estimates of the proportions of repeated sequences of each of the cereal genomes that are homologous with repeated sequences in the other species have been determined and a phylogenetic tree of cereal evolution constructed on the basis of the repeated sequence DNA homologies. It is proposed that wheat and rye diverged after their common ancestor had diverged from the ancestor of barley. This was preceded by the divergence of the common ancestor of wheat, rye and barley and the ancestor of oats. Once introduced in Gramineae evolution most families of repeated sequences appear to have been maintained in all subsequently diverging species. — The repeated sequences of oats, barley, wheat and rye have been divided into Groups based upon their presence or absence in different species. Repeated sequences of related families are more closely related to one another within a species than between species. It is suggested that this is because repeated sequences have been involved in many rounds of amplification or quantitative change via unequal crossing over during species divergence in cereal evolution.     

The protein sequence homology of gamma-crystallins among major vertebrate classes and their DNA sequence homology to heat-shock protein genes

A systematic characterization of lens crystallins from five major classes of vertebrates was carried out by exclusion gel filtration, cation-exchange chromatography and N-terminal sequence determination. All crystallin fractions except that of -crystallin were found to be N-terminally blocked. -Crystallin is present in major classes of vertebrates except the bird, showing none, or decreased amounts, of this protein in chicken and duck lenses, respectively. N-Terminal sequence analysis of the purified -crystallin polypeptides showed extensive homology between different classes of vertebrates, supporting the close relatedness of this family of crystallin even from the evolutionarily distant species. Comparison of nucleotide sequences and their predicted amino acid sequences between -crystallins of carp and rat lenses and heat-shock proteins demonstrated partial sequence homology of the encoded polypeptides and striking homology at the gene level. The unexpected strong homology of complementary DNA (cDNA) lies in the regions coding for 40 N-terminal residues of carp -II, rat 2-1, and the middle segments of 23,000- and 70,000-M _r heat-shock proteins. The optimal alignment of DNA sequences along these two segments shows about 50% homology. The percentage of protein sequence identity for the corresponding aligned segments is only 20%. The weak sequence homology at the protein level is also found between the invertebrate squid crystallin and rat -crystallin polypeptides. These results pointed to the possibility of unifying three major classes of vertebrate crystallins into one // superfamily and corroborated the previous supposition that the existing crystallins in the animal kingdom are probably mutually interrelated, sharing a common ancestry.     

On the local cardiac renin angiotensin system. Basic and clinical implications

In the present review we reevaluated the experimental and clinical evidence that there is a local renin angiotensin system in the heart as well as the presence of a functional intracrine component which is activated during pathological conditions like heart failure and hypertension. The implications of these findings for cardiology were discussed. The novel finding that cell swelling impairs cell coupling and impulse propagation through activation of ionic channels with consequent generation of cardiac arrhythmias and the evidence that AT1 receptors are mechanosensors able to alter the heart function independently of Ang II were discussed. Particular attention was given to the role of salt loading on the activation of a local cardiac renin angiotensin and its consequences.     

Phylogenetic estimation of Mytilidae in the East China Sea inferred from mitochondrial genes and nuclear DNA sequence variation

We performed a phylogenetic estimation of the family Mytilidae in the East China Sea based on nuclear internal transcribed spacer (ITS) genes and two mitochondrial genes (COI and 16S RNA). Analysis of five mytilid species based on each of the three genes resulted in mostly congruent trees, although there were some discrepancies in the classification of these species. We combine the results obtained from the three separate analyses to provide a phylogenetic estimation of Mytilidae. We found that the Mytilidae was divided into two major lineages: in one clade, Mytilus galloprovincialis was grouped with Mytilus coruscus; in the second clade, Septifer bilocularis was placed at the basal position in an individual clade, and Perna viridis and Musculista senhousia were recovered as a monophyletic group. Although these finding provide important insights into the taxonomic relationships among the Mytilidae, many aspects of Mytilidae phylogeny remain unresolved. Further analysis based on more molecular information and extensive taxon sampling is necessary to elucidate the phylogenetic relationships among the major lineages within the Mytilidae.