Angiotensin Converting Enzymes Play a Dominant Role in Fertility
Written by Ben Bunting: BA(Hons), PGCert.
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ACE1 is one of the major pathways in the OVRAS and AngII signaling pathways. ACE1 is also known to be a major cause of oxidative stress and promotes apoptosis, a process that is detrimental to fertility.
tACE1
ACE1 is a key regulator of fertility in mice. When sperm undergo a capacitation process and undergo a morphological change known as the acrosome reaction, the epididymal protein ACE1 modifies the sperm membranes to facilitate successful sperm-egg interactions. ACE1 in the epididymis is also involved in regulating sperm motility. ACE1 and its homolog ADAM family members are essential for normal mouse fertility. ACE1 is also produced in the germ cells of humans.
In human women, the polycystic ovary is one of the leading causes of infertility, affecting five to 7% of women of reproductive age. Although the cause of PCOS is not clear, there are evidences that alterations in angiotensin-converting enzymes (ACEs) and the renin-angiotensin system (RAS) are involved. Ace1-/ and Ace2-/ mice have been found to be sterile and abnormal, while Ace3-/ mice are fertile and gestational.
The study has several implications. For example, the presence of an extra gene known as tACE1 may result in decreased fertility. The gene also increases the risk of pelvic infections, blocked fallopian tubes, and uterine fibroids. These conditions may have an impact on the development of a child, and the researchers hope that by using this gene, they can treat infertility and help couples achieve childbearing.
Air pollution can influence fertility in humans. Although it is difficult to prove causality in humans, studies conducted in Sao Paulo, Brazil, have shown a relationship between air pollution and spontaneous fertility. In the case of the Sao Paulo study, researchers found a reduction in newborns per mouse, as well as an increase in the failure rate of embryo implantation.
ADAM3
The role of ADAM3 in fertility is not well understood. However, the role of ACE in fetal development and the infertility problem in some populations has been linked to the renin-angiotensin system. Consequently, alterations in the expression of angiotensin converting enzymes may be one of the major causes of infertility. ADAM3 is a pseudogene, and further research is necessary to understand the role of this enzyme in fertility.
The function of ADAM3 is not known, although it is involved in the formation of fertile spermatozoa in mice. Moreover, ACE is a prominent regulator of the reproductive system. In mice, ACE1 and ACE2 are associated with the sperm-egg fusion process. Although double mutant mouse models have not yet been investigated, they could provide insights into the role of ACEs in fertility.
ADAM3 plays a central role in fertilization. It inhibits acrosome reaction, which is essential for successful interaction of sperm and egg. Moreover, ADAM3 releases ACE1, which reduces sperm motility during epididymal passage. Therefore, ADAM3 is essential for normal mouse fertility.
Male mice with sTst mutation lack somatic ACE and have low blood pressure. These mice also exhibit renal atrophy and abnormal kidney arteries. Interestingly, the homozygous mutant mice have normal fertility. Males homozygous for the sTst mutation also have normal sperm counts and histology. In addition, these mice also have normal sperm morphology.
IZUMO1
IZUMO1 plays a dominant reproductive role in mammals, including humans. The IZUMO1 complex binds to a subset of solubilized oolemmal proteins. In the mouse sperm, IZUMO1 is a member of two high-molecular-weight protein complexes that interact with lipid rafts. This complex also interacts with GLIPR1L1. This interaction is dynamically remodeled upon acrosome exocytosis. In mice, selective ablation of GLIPR1L1 prevents IZUMO1 redistribution to the acrosome.
The IZUMO1-MAIA complex mediates the interaction between sperm and oocyte during fertilization. In vivo experiments, gene knockout mice showed that three genes are required for gamete binding: CD9, JUNO, and IZUMO1. When these genes were deleted from mice, the animals failed to fertilize. The failure of fertilization was associated with abnormalities in the final adhesion/fusion steps. However, the other steps of fertilization were not affected.
The fusion of gametes is an essential event in vertebrate fertilization. This fusion allows the spermatozoon to enter the ooplasm and triggers the resumption of meiosis. In mouse, the membrane-fusion process involves the binding of the sperm-egg fusion protein Juno to the egg membrane. The egg membrane contains a network of tetraspanins that facilitates binding between the two proteins. When both receptors are depleted, the fusion process fails.
To determine whether Glipr1l1 is essential for IZUMO1 function, a Glipr1l1-/ mouse line was generated. This line contains a mutated gene encoding a premature stop codon in exon 1. This frame-shift mutation produces a 4-kDa fragment of GLIPR1L1 protein. This mutation results in a 92% reduction in Glipr1l1 mRNA expression in the testis. Furthermore, immunofluorescent labeling confirmed the absence of Glipr1l1.
The hybrid protein was introduced into an Izumo1-null background. Interestingly, this protein was also biologically functional and induced litter size. The hybrid protein was able to produce approximately 9.5 pups, which is comparable to wild-type mice.
AT1-AA
The RAS is an important communication system that regulates the reproductive functions in both males and females. It is involved in several physiological and pathological processes, including the production of hormones and the formation of the endometrial lining. It also participates in many processes related to male fertility, including fertilization.
The AT1-AA titer in plasma was significantly higher in the HELLP group than in the control group. It also correlated with the grade of HELLP and the level of TNF-a and ET-1 in the blood. These findings are consistent with the theory that AT1-AA is responsible for causing the HELLP syndrome.
Preeclampsia is the leading cause of maternal and fetal mortality and morbidity. It can cause long-term effects on offspring and may contribute to postpartum cardiovascular disease. Though its cause is unknown, elevated levels of agonistic autoantibodies, such as AT1-AA, are associated with a higher risk of the disease.
The AT1-AA inhibits RUPP, a process that decreases blood flow to the growing fetus. The inhibition of AT1-AA blocks RUPP in pregnant rats, and the results suggest that the treatment improves fetal and maternal outcomes.
The AT1-AA gene is expressed in the testes of both rats and mice. The expression of Ang (II) and AT2R depends on age. Ang II and Ang I play an important role in regulating sperm motility. In mouse models, the AT1-AA gene is expressed mainly in the leydig cells. Its presence in mouse testes has also been associated with spermatogenesis.
During the in vitro fertilization process, tACE protein levels in the sperm differ during the acrosome reaction and the capacitation phases. These differences may influence the sperm's physiology and ability to fertilize the oocyte. Male mice lacking sACE do not show any effect on fertility, but mice lacking both ACE isoforms show reduced fertility.
COVID-19
Men are especially susceptible to COVID-19 infection, and the virus has been classified as a pandemic by the World Health Organization (WHO). The virus impairs the function of angiotensin converting enzymes, which are responsible for the production of acetylcholine and nitric oxide. This may explain why males with COVID-19 often experience problems with male fertility. The virus affects the testis by altering the expression of ACE2 in the testicular cells.
The COVID-19 virus is a unique global situation, but countries have implemented strategies to curb its spread and limit its symptoms. These measures are in line with the World Health Organization's recommendations and are meant to protect patients from the disease. Furthermore, scientific societies have provided guidance for treating COVID-19-infected women undergoing IVF. Although the COVID-19 virus has not been shown to impact the outcome of IVF, many women have been delayed in their treatments while a response to the virus is being established.
Males with COVID-19 infection should undergo urological examination. Moreover, the condition should be closely monitored because the disease may impair male fertility. Infection of the testes with COVID-19 can disrupt spermatogenesis by impairing spermatogenesis and triggering an immune response.
During IVF treatment with COVID-19-infected asymptomatic patients, general precautions in the laboratory should be modified. For example, there should be physical barriers in the laboratory and screening rooms to prevent exposure to COVID-19. In addition, the clinic staff must limit their contact with COVID-19-infected patients.
COVID-19 is a virus that enters host cells by targeting the ACE2 receptor on a specific protein. The virus is capable of infecting various organs. In addition to the respiratory system, it affects the development of various tissues including the intestines.
Conclusion
The role of ACE1 in fertility remains unclear. The enzyme is involved in intraovarian regulation, but it may also affect the follicle development. In rats and rabbits, ACE1 inhibition reduces the infertility induced by AngII. In addition to influencing follicle development, ACE1 also leads to increased oxidative stress. Oxidative stress contributes to inflammatory reactions and impairs human reproduction.
In humans, the RAS is comprised of two major hormones: angiotensin and renin. Both renin and angiotensinogen are produced by the kidneys. The angiotensin-converting enzymes ACE1 and ACE2 are involved in the production of angiotensin peptides. Both of these hormones are essential for fertility.
In male mice, tAce1-/ mice have impaired fertility. However, sAce1-/ mice are rescued when tACE1 is expressed in germ cells. Thus, ACE1 and ACE2 are important for male and female fertility. Although it is unclear how these enzymes regulate the process of fertilization, it is important to understand the roles of these hormones in the reproductive process.
The RAS has a vital role in controlling blood pressure. However, recent research has found that the RAS is also involved in male infertility. Some studies show that this system also regulates spermatogenesis. Since sperm and semen contain components of the RAS, this may be a crucial mechanism in male infertility.
