Physiological and pathological roles of Ang II and Ang- (1-7) in the female reproductive system

Gating Mechanism for Biased Agonism at Angiotensin II Type 1 Receptors

For the interaction of angiotensin II (AngII) with AngII type 1 receptors (AT1R), two potential proton hopping pathways have been identified, each associated with distinct physiological outcomes. The octapeptide AngII (Asp1-Arg2-Val3-Tyr4-Ile5-His6-Pro7-Phe8) appears to form a charge relay system (CRS) in solution in which the C-terminal carboxylate abstracts a proton from the His6 imidazole group, which, in turn, abstracts a proton from the Tyr4 hydroxyl (OH) group, creating a tyrosinate anion. When AngII binds to the AT1R, the CRS can be reconstituted with D281 of the receptor taking up the role of the Phe8 carboxylate in the tripartite interaction, whilst the Phe8 carboxylate forms a salt bridge with K199 of the receptor. As a consequence, the Tyr4 OH of AngII is positioned with accessibility to either the Phe8 carboxylate (bound to K199) or the His6 imidazole (activated by D281), thereby creating a potential gating mechanism for AT1R receptor signaling. This study summarizes evidence based on structure activity data for various analogs wherein Tyr4 OH interaction with His6 imidazole (CRS formation) leads to G protein sequestration and vasoconstriction, whereas Tyr4 OH interaction with Phe8 carboxylate (bound to K199) engenders arrestin-mediated vasodilation and receptor desensitization. These findings, combined with quantum mechanical (semiempirical) calculations of CRS proton transfer presented herein, provide insights for the therapeutic targeting of angiotensin receptor blockers (sartans) and the development of second-generation drugs (bisartans).

Single cell RNA sequencing reveals the role of local renin-angiotensin system in regulating ovarian physiological cycle and promoting PCOS

There is a local renin-angiotensin system (RAS) in the ovary, which is involved in regulating many important physiological processes, but the specific mechanism remains unclear. Polycystic ovarian syndrome (PCOS) is the most frequently reported non-iatrogenic condition with abnormal RAS expression, characterized by overweight or obesity and insulin resistance (IR), both of which are significantly correlated with many long-term complications. These conditions are closely linked to circulatory or local RAS, serving as potential common regulatory nodes. The present study analyzed single-cell RNA sequencing (scRNA-seq) data from mouse ovaries during the reproductive period to obtain the expression levels and location information of RAS components in all cell clusters. It further analyzed the cyclical fluctuations of RAS and the differential gene sets during the estrous cycle. Protein-protein interaction analysis predicted the most closely interacting pathway with RAS, and preliminary evidence of crosstalk between angiotensin II (AngII) and the insulin signaling pathway was identified in the scRNA-seq data. A PCOS mouse model was constructed, replicating clinical reproductive and metabolic complications, and the crosstalk between AngII and IRS1/PI3K/AKT was verified. In conclusion, this study revealed the dynamic changes of the ovarian local RAS at the cellular level during the estrous cycle, and described the role of RAS in regulating ovarian function from a single-cell perspective. It also provided evidence that IR, caused by the crosstalk between AngII and IRS1/PI3K/AKT pathways, may be a potential underlying mechanism of PCOS.

Vasohibins in Health and Disease: From Angiogenesis to Tumorigenesis, Multiorgan Dysfunction, and Brain-Heart Remodeling

Vasohibins (VASHs), comprising VASH-1 and VASH-2, were initially identified as regulators of angiogenesis. Recent studies, however, have unveiled their novel role in fibrosis and microtubule detyrosination. The dysregulated expression of VASHs is associated with several pathological processes, such as angiogenesis dysfunction, microtubule detyrosination, and fibrosis, contributing to various diseases. These findings suggest the pleiotropic effects of VASHs in multiple organs and systems beyond angiogenesis. This review explores the molecular properties of VASHs and their emerging functions in tubulin carboxyl activity and microtubule detyrosination-key to brain and cardiac remodeling. We also discuss the potential therapeutic applications of their interference in diseases such as tumorigenesis, as well as renal-, reproductive-, and liver-related diseases.

Renal Function and the Role of the Renin-Angiotensin-Aldosterone System (RAAS) in Normal Pregnancy and Pre-Eclampsia

Objective: Pre-eclampsia (PE) is a complex, advancing condition marked either by the recent emergence of hypertension and proteinuria or by the recent onset of hypertension accompanied by notable end-organ impairment, which may occur with or without proteinuria. PE usually appears in the postpartum phase or after the 20th week of gestation, though it might appear sooner in cases of molar pregnancy. Pathophysiology: This disorder is a serious multisystem condition during pregnancy that can lead to serious, life-threatening complications for both the mother and the fetus if it is not diagnosed and managed promptly. These changes result from widespread and intense vasoconstriction caused by renin, angiotensin II (Ang II), aldosterone, and catecholamines. The renin-angiotensin-aldosterone system (RAAS) and its sequence of signaling reactions demonstrate its crucial role in regulating blood pressure and electrolyte balance that diverges in PE from that observed in healthy pregnancies. However, it is widely recognized that the above description is incomplete for pre-eclampsia and further relationships should be analyzed. The purpose of this article is to review and synthesize alterations in renal function and the RAAS during normal pregnancy and pre-eclampsia. We aim to provide clinical gynecologists with a comprehensive understanding of how pregnancy-specific adaptations can impact renal function and the RAAS, as well as the deviations observed in pre-eclampsia. Conclusion: This information is essential to enhance clinical awareness, improve the accuracy of diagnosis, and support evidence-based decision-making in the management of pregnant patients, especially those complicated by pre-eclampsia.

The renin-angiotensin-aldosterone system: An old tree sprouts new shoots

The intricate physiological and pathological diversity of the Renin-Angiotensin-Aldosterone System (RAAS) underpins its role in maintaining bodily equilibrium. This paper delves into the classical axis (Renin-ACE-Ang II-AT1R axis), the protective arm (ACE2-Ang (1-7)-MasR axis), the prorenin-PRR-MAP kinases ERK1/2 axis, and the Ang IV-AT4R-IRAP cascade of RAAS, examining their functions in both physiological and pathological states. The dysregulation or hyperactivation of RAAS is intricately linked to numerous diseases, including cardiovascular disease (CVD), renal damage, metabolic disease, eye disease, Gastrointestinal disease, nervous system and reproductive system diseases. This paper explores the pathological mechanisms of RAAS in detail, highlighting its significant role in disease progression. Currently, in addition to traditional drugs like ACEI, ARB, and MRA, several novel therapeutics have emerged, such as angiotensin receptor-enkephalinase inhibitors, nonsteroidal mineralocorticoid receptor antagonists, aldosterone synthase inhibitors, aminopeptidase A inhibitors, and angiotensinogen inhibitors. These have shown potential efficacy and application prospects in various clinical trials for related diseases. Through an in-depth analysis of RAAS, this paper aims to provide crucial insights into its complex physiological and pathological mechanisms and offer valuable guidance for developing new therapeutic approaches. This comprehensive discussion is expected to advance the RAAS research field and provide innovative ideas and directions for future clinical treatment strategies.

Transplantation of human umbilical cord-derived mesenchymal stem cells improves age-related ovarian functional decline via regulating the local renin-angiotensin system on inflammation and oxidative stress

BACKGROUND

Age-related reproductive aging is a natural and irreversible physiological process, and delaying childbearing is increasingly common all over the world. Transplantation of mesenchymal stem cells (MSCs) is considered a new and effective therapy to restore ovarian function, but the relevant mechanisms remain unclear. Recently, it has been found that there is a local Renin-angiotensin system (RAS) in human ovary and it plays a key role.

METHODS

After collecting follicular fluid from women who received oocyte retrieval for pure male factor infertility, the level of RAS components in it were detected, and the correlation analysis by linear regression. Then, the in vivo experiments on female C57BL/6 mice were designed to measure ovarian function, and the transcription and translation levels of RAS pathway were detected by molecular biology methods. Moreover, the role of RAS in regulating inflammation and oxidative stress in the co-culture system were explored in in vitro experiments on KGN cells.

RESULTS

First, a total of 139 samples of analyzable follicular fluid were obtained. The local RAS of ovary, which is independent of systemic RAS (P > 0.05), is affected by age (Pearson r < 0, P < 0.05) and related to ovarian function, inflammation, oxidative stress indexes and assisted reproduction laboratory outcomes (P < 0.05). Next, the ovary/body weight of aging mice decreased significantly and serum sex hormones levels changed significantly (P < 0.01). The number of functional follicles decreased, while the atresia follicles increased (P < 0.05). After MSCs transplantation, all the above measures have been partially recovered (P < 0.05). Although several RAS components in aging ovary changed, MSCs only improved the expression level of AT1R (P < 0.05). Furthermore, the secretion ability and mitochondrial membrane potential of aging KGN cells decreased, while the intracellular ROS level and the aging cells ratio increased (P < 0.01). All the above measures have been partially recovered when co-cultured with MSCs (P < 0.05). After Ang(1-7) were added into the co-culture system, the above have been more significantly restored compared with Ang II (P < 0.05). Nevertheless, there was no statistical difference in estradiol level no matter which one was added (P > 0.05).

CONCLUSIONS

Together, our findings indicate that a novel possible mechanism to explain how stem cells restore age-related ovarian functional decline.

Proteomics profiling reveals lipid metabolism abnormalities during oogenesis in unexplained recurrent pregnancy loss

Background

Unexplained recurrent pregnancy loss (URPL) is a clinical dilemma in reproductive fields. Its diagnosis is mainly exclusionary after extensive clinical examination, and some of the patients may still face the risk of miscarriage.

Methods

We analyzed follicular fluid (FF) from in vitro fertilization (IVF) in eight patients with URPL without endocrine abnormalities or verifiable causes of abortion and eight secondary infertility controls with no history of pregnancy loss who had experienced at least one normal pregnancy and delivery by direct data-independent acquisition (dDIA) quantitative proteomics to identify differentially expressed proteins (DEPs). In this study, bioinformatics analysis was performed using online software including g:profiler, String, and ToppGene. Cytoscape was used to construct the protein-protein interaction (PPI) network, and ELISA was used for validation.

Results

Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the DEPs are involved in the biological processes (BP) of complement and coagulation cascades. Apolipoproteins (APOs) are key proteins in the PPI network. ELISA confirmed that APOB was low-expressed in both the FF and peripheral blood of URPL patients.

Conclusion

Dysregulation of the immune network intersecting coagulation and inflammatory response is an essential feature of URPL, and this disequilibrium exists as early as the oogenesis stage. Therefore, earlier intervention is necessary to prevent the development of URPL. Moreover, aberrant lipoprotein regulation appears to be a key factor contributing to URPL. The mechanism by which these factors are involved in the complement and coagulation cascade pathways remains to be further investigated, which also provides new candidate targets for URPL treatment.

Classical and nonclassical effects of angiotensin-converting enzyme: How increased ACE enhances myeloid immune function

As part of the classical renin-angiotensin system, the peptidase angiotensin-converting enzyme (ACE) makes angiotensin II which has myriad effects on systemic cardiovascular function, inflammation, and cellular proliferation. Less well known is that macrophages and neutrophils make ACE in response to immune activation which has marked effects on myeloid cell function independent of angiotensin II. Here, we discuss both classical (angiotensin) and nonclassical functions of ACE and highlight mice called ACE 10/10 in which genetic manipulation increases ACE expression by macrophages and makes these mice much more resistant to models of tumors, infection, atherosclerosis, and Alzheimer's disease. In another model called NeuACE mice, neutrophils make increased ACE and these mice are much more resistant to infection. In contrast, ACE inhibitors reduce neutrophil killing of bacteria in mice and humans. Increased expression of ACE induces a marked increase in macrophage oxidative metabolism, particularly mitochondrial oxidation of lipids, secondary to increased peroxisome proliferator-activated receptor α expression, and results in increased myeloid cell ATP. ACE present in sperm has a similar metabolic effect, and the lack of ACE activity in these cells reduces both sperm motility and fertilization capacity. These nonclassical effects of ACE are not due to the actions of angiotensin II but to an unknown molecule, probably a peptide, that triggers a profound change in myeloid cell metabolism and function. Purifying and characterizing this peptide could offer a new treatment for several diseases and prove potentially lucrative.

Trehalosemodulates OVRAS to improve oxidative stress and apoptosis in KGN cells and ovaries of PCOS mice

The etiology of polycystic ovary syndrome (PCOS) is complex and variable, and there is no exact cause or good treatment method. Most of the methods of hormones are used to temporarily meet the needs of patients. Experimental evidence has shown that trehalose has, anti-apoptotic, anti-oxidative, glucose-lowering, and insulin resistance effects. However, whether trehalose has a therapeutic effect on PCOS is unknown. It has been reported that the ovarian renin-angiotensin system (OVRAS) is involved in the development of PCOS, but it has not been fully elucidated. This study aims to explore the effect of trehalose on PCOS and elucidate the related OVRAS mechanism. We first observed that body weight, estrous cycle, ovarian follicles at all levels, glucose tolerance, serum hormones, and insulin resistance were improved by trehalose treatment in the PCOS mouse model. Moreover, trehalose treatment also ameliorated ovarian oxidative stress and apoptosis in PCOS mice, as determined by TUNNEL apoptosis staining, total SOD in ovarian homogenate, and WB assay. OVRAS mainly involves two classic pathways, namely the ACE/AngII/AT1R/AT2R, and ACE2 / Ang1-7/ MASR, Which play different functions. In PCOS mouse ovaries, we found that ACE/AngII/AT1R was up-regulated and ACE2/Ang1-7/MASR and AT2R were down-regulated by PCR and WB experiments, However, trehalose treatment changed its direction. In addition, we also found that trehalose ameliorated DHEA-induced oxidative stress and apoptosis in KGN by PCR and WB experiments, mainly by down-regulating ACE/AngII/AT1R. Our study shows that trehalose improves symptoms of PCOS mainly by down-regulating ACE/AngII/AT1R, revealing a potential therapeutic target for PCOS.

Exogenous Nucleotides Ameliorate Age-Related Decline in Testosterone in Male Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice by Modulating the Local Renin-Angiotensin System Antioxidant Pathway

In older men, an age-related decline in testosterone is closely associated with various adverse health outcomes. With the progression of aging, hyperactivation of the local renin-angiotensin system (RAS) and oxidative stress increase in the testis. The regulation of RAS antioxidants may be a target to delay testicular aging and maintain testosterone levels. Exogenous nucleotides (NTs) have anti-aging potential in several systems, but there are no studies of their effects on the reproductive system. In our study, we examined the effects of exogenous NTs on testosterone synthesis and explored possible mechanisms of action. Therefore, senescence-accelerated mouse prone-8 (SAMP8) mice and senescence-accelerated mouse resistant 1 (SAMR1) were used in the experiment, and they were randomly divided into an NTs free group (NTs-F), a normal control group (control), a low-dose NTs group (NTs-L), a middle-dose NTs (NTs-M), a high-dose NTs group (NTs-H) and SAMR1 groups, and the testis of the mice were collected for testing after 9 months of intervention. The results showed that exogenous NTs could increase the testicular organ index in mice during aging, and delayed the age-associated decline in testosterone levels in SAMP8 male mice, possibly by modulating the local RAS antioxidant pathway and reducing oxidative stress to protect the testis. The present study provides new research clues for the development of preventive and therapeutic strategies for related diseases.

Unraveling the relationship between the renin-angiotensin system and endometrial cancer: a comprehensive review

Endometrial cancer (EC), the most common adenocarcinoma, represents 90% of uterine cancer in women with an increased incidence of occurrence attributed to age, obesity, hypertension, and hypoestrogenism. Being the most common gynecological malignancy in women, it shows a relation with the activation of different components of the renin-angiotensin system (RAS), which is predominantly involved in maintaining blood pressure, salt, water, and aldosterone secretion, thereby playing a significant role in the etiology of hypertension. The components of the RAS, i.e., ACE-I, ACE-II, AT1R, AT2R, and Pro(renin) receptor, are widely expressed in both glandular and stromal cells of the endometrium, with varying levels throughout the different phases of the menstrual cycle. This causes the endometrial RAS to implicate angiogenesis, neovascularization, and cell proliferation. Thus, dysfunctioning of the endometrial RAS could predispose the growth and spread of EC. Interestingly, the increased expression of AngII, AGTR1, and AGTR2 showed advancement in the stages and progression of EC via the prorenin/ATP6AP2 and AngII/AGTR1 pathway. Therefore, this review corresponds to unraveling the relationship between the progression and development of endometrial cancer with the dysfunction in the expression of various components associated with RAS in maintaining blood pressure.