Autophagy is involved in high glucose-induced heart tube malformation

Atractylenolide-I Alleviates Hyperglycemia-Induced Heart Developmental Malformations through Direct and Indirect Modulation of the STAT3 Pathway

BACKGROUND

Gestational diabetes could elevate the risk of congenital heart defects (CHD) in infants, and effective preventive and therapeutic medications are currently lacking. Atractylenolide-I (AT-I) is the active ingredient of Atractylodes Macrocephala Koidz (known as Baizhu in China), which is a traditional pregnancy-supporting Chinese herb.

PURPOSE

In this study, we investigated the protective effect of AT-I on the development of CHD in embryos exposed to high glucose (HG).

STUDY DESIGN AND METHODS

First, systematic review search results revealed associations between gestational diabetes mellitus (GDM) and cardiovascular malformations. Subsequently, a second systematic review indicated that heart malformations were consistently associated with oxidative stress and cell apoptosis. We assessed the cytotoxic impacts of Atractylenolide compounds (AT-I, AT-II, and AT-III) on H9c2 cells and chick embryos, determining an optimal concentration of AT-I for further investigation. Second, immunofluorescence, western blot, Polymerase Chain Reaction (PCR), and flow cytometry were utilized to delve into the mechanisms through which AT-I mitigates oxidative stress and apoptosis in cardiac cells. Molecular docking was employed to investigate whether AT-I exerts cardioprotective effects via the STAT3 pathway. Then, we developed a streptozotocin-induced diabetes mellitus (PGDM) mouse model to evaluate AT-I's protective efficacy in mammals. Finally, we explored how AT-I protects hyperglycemia-induced abnormal fetal heart development through microbiota analysis and untargeted metabolomics analysis.

RESULTS

The study showed the protective effect of AT-I on embryonic development using a chick embryo model which rescued the increase in the reactive oxygen species (ROS) and decrease in cell survival induced by HG. We also provided evidence suggesting that AT-I might directly interact with STAT3, inhibiting its phosphorylation. Further, in the PGDM mouse model, we observed that AT-I not only partially alleviated PGDM-related blood glucose issues and complications but also mitigated hyperglycemia-induced abnormal fetal heart development in pregnant mice. This effect is hypothesized to be mediated through alterations in gut microbiota composition. We proposed that dysregulation in microbiota metabolism could influence the downstream STAT3 signaling pathway via EGFR, consequently impacting cardiac development and formation.

CONCLUSIONS

This study marks the first documented instance of AT-I's effectiveness in reducing the risk of early cardiac developmental anomalies in fetuses affected by gestational diabetes. AT-I achieves this by inhibiting the STAT3 pathway activated by ROS during gestational diabetes, significantly reducing the risk of fetal cardiac abnormalities. Notably, AT-I also indirectly safeguards normal fetal cardiac development by influencing the maternal gut microbiota and suppressing the EGFR/STAT3 pathway.

Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases

Autophagy is a dynamic self-renovation biological process that maintains cell homeostasis and is responsible for the quality control of proteins, organelles, and energy metabolism. The E1-like ubiquitin-activating enzyme autophagy-related gene 7 (ATG7) is a critical factor that initiates classic autophagy reactions by promoting the formation and extension of autophagosome membranes. Recent studies have identified the key functions of ATG7 in regulating the cell cycle, apoptosis, and metabolism associated with the occurrence and development of multiple diseases. This review summarizes how ATG7 is precisely programmed by genetic, transcriptional, and epigenetic modifications in cells and the relationship between ATG7 and aging-related diseases.

Baicalin administration could rescue high glucose-induced craniofacial skeleton malformation by regulating neural crest development

Hyperglycemia in pregnancy can increase the risk of congenital disorders, but little is known about craniofacial skeleton malformation and its corresponding medication. Our study first used meta-analysis to review the previous findings. Second, baicalin, an antioxidant, was chosen to counteract high glucose-induced craniofacial skeleton malformation. Its effectiveness was then tested by exposing chicken embryos to a combination of high glucose (HG, 50 mM) and 6 μM baicalin. Third, whole-mount immunofluorescence staining and in situ hybridization revealed that baicalin administration could reverse HG-inhibited neural crest cells (NCC) delamination and migration through upregulating the expression of Pax7 and Foxd3, and mitigate the disordered epithelial-mesenchymal transition (EMT) process by regulating corresponding adhesion molecules and transcription factors (i.e., E-cadherin, N-cadherin, Cadherin 6B, Slug and Msx1). Finally, through bioinformatic analysis and cellular thermal shift assay, we identified the AKR1B1 gene as a potential target. In summary, these findings suggest that baicalin could be used as a therapeutic agent for high glucose-induced craniofacial skeleton malformation.

Arsenic disturbs neural tube closure involving AMPK/PKB-mTORC1-mediated autophagy in mice

Arsenic exposure is a significant risk factor for folate-resistant neural tube defects (NTDs), but the potential mechanism is unclear. In this study, a mouse model of arsenic-induced NTDs was established to investigate how arsenic affects early neurogenesis leading to malformations. The results showed that in utero exposure to arsenic caused a decline in the normal embryos, an elevated embryo resorption, and a higher incidence of malformed embryos. Cranial and spinal deformities were the main malformation phenotypes observed. Meanwhile, arsenic-induced NTDs were accompanied by an oxidant/antioxidant imbalance manifested by elevated levels of reactive oxygen species (ROS) and decreased antioxidant activities. In addition, changes in the expression of autophagy-related genes and proteins (ULK1, Atg5, LC3B, p62) as well as an increase in autophagosomes were observed in arsenic-induced aberrant brain vesicles. Also, the components of the upstream pathway regulating autophagy (AMPK, PKB, mTOR, Raptor) were altered accordingly after arsenic exposure. Collectively, our findings propose a mechanism for arsenic-induced NTDs involving AMPK/PKB-mTORC1-mediated autophagy. Blocking autophagic cell death due to excessive autophagy provides a novel strategy for the prevention of folate-resistant NTDs, especially for arsenic-exposed populations.

EGFR/MAPK signaling pathway acts as a potential therapeutic target for sulforaphane-rescued heart tube malformation induced by various concentrations of PhIP exposure

BACKGROUND

2-Amino-1-methyl-6-phenylimidazo [4,5-b] pyrimidine (PhIP) is a known carcinogen generated mainly from cooking meat and environmental pollutants. It is worth exploring the potential of natural small-molecule drugs to protect against adverse effects on embryonic development.

PURPOSE

In this study, we investigated the potential toxicological effects of PhIP on embryonic heart tube formation and the effect of Sulforaphane (SFN) administration on the anti-toxicological effects of PhIP on embryonic cardiogenesis.

STUDY DESIGN AND METHODS

First, the chicken embryo model was used to investigate the different phenotypes of embryonic heart tubes induced by various concentrations of PhIP exposure. We also proved that SFN rescues PhIP-induced embryonic heart tube malformation. Second, immunofluorescence, western blot, Polymerase Chain Reaction (PCR) and flow cytometry experiments were employed to explore the mechanisms by which SFN protects cardiac cells from oxidative damage in the presence of PhIP. We used RNA-seq analysis, molecular docking, in situ hybridization, cellular thermal shift assay and solution nuclear magnetic resonance spectroscopy to explore whether SFN protects cardiogenesis through the EGFR/MAPK signaling pathway.

RESULTS

The study showed that PhIP might dose-dependently interfere with the C-looping heart tube (mild) or the fusion of a pair of bilateral endocardial tubes (severe) in chick embryos, while SFN administration prevented cardiac cells from oxidative damage in the presence of high-level PhIP. Furthermore, we found that excessive reactive oxygen species (ROS) production and subsequent apoptosis were not the principal mechanisms by which low-level PhIP induced malformation of heart tubes. This is due to PhIP-disturbed Mitogen-activated protein kinase (MAPK) signaling pathway could be corrected by SFN administration.

CONCLUSIONS

This study provided novel insight that PhIP exposure could increase the risk of abnormalities in early cardiogenesis and that SFN could partially rescue various concentrations of PhIP-induced abnormal heart tube formation by targeting EGFR and mediating EGFR/MAPK signaling pathways.

Effectiveness of Scutellaria baicalensis Georgi root in pregnancy-related diseases: A review

The root of Scutellaria baicalensis Georgi, also called Huangqin, is frequently used in traditional Chinese medicine. In ancient China, S. baicalensis root was used to clear heat, protect the fetus, and avoid a miscarriage for thousands of years. In modern times, pregnancy-related diseases can seriously affect maternal and fetal health, but few systematic studies have explored the mechanisms and potential targets of S. baicalensis root in the treatment of pregnancy-related diseases. Flavonoids (baicalein, wogonin and oroxylin A) and flavonoid glycosides (baicalin and wogonoside) are the main chemical components in the root of S. baicalensis. This study presents the current understanding of the major chemical components in the root of S. baicalensis, focusing on their traditional uses, potential therapeutic effects and ethnopharmacological relevance to pregnancy-related disorders. The mechanisms, potential targets and experimental models of S. baicalensis root for ameliorating pregnancy-related diseases, such as recurrent spontaneous abortion, preeclampsia, preterm birth, fetal growth restriction and gestational diabetes mellitus, are highlighted.

Different cellular mechanisms from low- and high-dose zinc oxide nanoparticles-induced heart tube malformation during embryogenesis

With the wide application of nanometer materials in daily life, people pay more attention to the potential toxicity of nanoparticles to human fetal development once the nanoparticles are absorbed into the human body during pregnancy. However, there was no directly solid evidence for ZnO NPs-caused congenital heart defects. Hence, we investigated the effect of ZnO NPs exposure on early cardiogenesis using the chicken/mouse embryo models. First, we showed ZnO NPs reduced H9c2 cell viability in a dose- and time-dependent manner, while cell autophagy was significantly activated too on the same pattern. During early cardiogenesis, ZnO NPs exposure increased the chance of heart tube malformation, while precardiac cell apoptosis rises in the phenotype of closure defect and Bifida. The hypertrophy was also observed in late-stage chicken/mouse survival embryos exposed to ZnO NPs. Apart from cell apoptosis, high-dose ZnO NPs exposure led to massive programmed necrosis, and further experiments verified that ferroptosis remained primarily in ZnO NPs-induced programmed necrosis. We also revealed that the toxicology of low-dose ZnO NPs was mainly featured in the changes of expressions of key genes instead of causing precardiac cell death. MYL2 and CSRP3 could work as the downstream molecules of the above key genes in the context of ZnO NPs exposure to early cardiogenesis based on RNA sequencing. Taken together, this study for the first time revealed the potential risk of heart tube malformation induced by ZnO NPs exposure through different cellular mechanisms, which depended on low- or high-dose ZnO NPs.

The Epidemiology and Mechanisms of Lifetime Cardiopulmonary Morbidities Associated With Pre-Pregnancy Obesity and Excessive Gestational Weight Gain

Obesity has reached pandemic proportions in the last few decades. The global increase in obesity has contributed to an increase in the number of pregnant women with pre-pregnancy obesity or with excessive gestational weight gain. Obesity during pregnancy is associated with higher incidence of maternal co-morbidities such as gestational diabetes and hypertension. Both obesity during pregnancy and its associated complications are not only associated with immediate adverse outcomes for the mother and their newborns during the perinatal period but, more importantly, are linked with long-term morbidities in the offsprings. Neonates born to women with obesity are at higher risk for cardiac complications including cardiac malformations, and non-structural cardiac issues such as changes in the microvasculature, e.g., elevated systolic blood pressure, and overt systemic hypertension. Pulmonary diseases associated with maternal obesity include respiratory distress syndrome, asthma during childhood and adolescence, and adulthood diseases, such as chronic obstructive pulmonary disease. Sequelae of short-term complications compound long-term outcomes such as long-term obesity, hypertension later in life, and metabolic complications including insulin resistance and dyslipidemia. Multiple mechanisms have been proposed to explain these adverse outcomes and are related to the emerging knowledge of pathophysiology of obesity in adults. The best investigated ones include the role of obesity-mediated metabolic alterations and systemic inflammation. There is emerging evidence linking metabolic and immune derangements to altered biome, and alteration in epigenetics as one of the intermediary mechanisms underlying the adverse outcomes. These are initiated as part of fetal adaptation to obesity during pregnancy which are compounded by rapid weight gain during infancy and early childhood, a known complication of obesity during pregnancy. This newer evidence points toward the role of specific nutrients and changes in biome that may potentially modify the adverse outcomes observed in the offsprings of women with obesity.

Endoplasmic reticulum stress-related calcium imbalance plays an important role on Zinc oxide nanoparticles-induced failure of neural tube closure during embryogenesis

Zinc oxide nanoparticles (ZnO NPs) have been increasingly and widely utilized in various fields, such as agriculture, food and cosmetics. However, various levels of adverse impacts of ZnO NPs on the ecological environment and public health have been associated with each stage of their production, use and disposal. ZnO NPs can be ingested by pregnant women and transferred to developing embryos/foetus through the placental barrier, however, the potential toxicity of ZnO NPs to embryonic and foetal development is largely unclear. In this study, we discovered that ZnO NPs exposure caused growth proportional failure of neural tube closure in mouse and chicken embryos and a simultaneous increase in apoptosis in the developing neural tubes of chicken embryos, which was verified in an in vitro experiment using the SH-SY5Y cell line. Furthermore, removal of free Zn²⁺ ions with EDTA or inhibition of Zn²⁺ ion absorption by CaCl₂ partially alleviated the neurotoxicity induced by ZnO NPs, implying that ZnO NPs-induced developmental neurotoxicity is probably due to both ZnO NPs and the Zn²⁺ ions released from ZnO NPs. In addition, we found that ZnO NPs exposure caused endoplasmic reticulum stress-mediated apoptosis driven mainly by an increase in intracellular calcium (Ca²⁺) concentrations, rather than by the activation of three membrane protein receptors (ATF6, IRE-1 and PERK). Thus, Ca²⁺ imbalance-mediated apoptosis in the context of ZnO NPs exposure may lead to cellular dysfunctions in developing neural precursors, such as, abnormalities involved in neural tube closure, ultimately leading to neural tube defects (NTDs) during embryogenesis. In sum, our results revealed that ZnO NPs exposure greatly increases the risk of failure of neural tube closure through endoplasmic reticulum stress-mediated neural cell death in the developing embryos, which may further lead to the NTD in fetal stage, including failure of neural tube closure.

Maternal obesity and metabolic disorders associate with congenital heart defects in the offspring: A systematic review

BACKGROUND

Congenital heart defects (CHDs) are the most common congenital malformations. The aetiology of CHDs is complex. Large cohort studies and systematic reviews and meta-analyses based on these have reported an association between higher risk of CHDs in the offspring and individual maternal metabolic disorders such as obesity, diabetes, hypertension, and preeclampsia, all conditions that can be related to insulin resistance or hyperglycaemia. However, the clinical reality is that these conditions often occur simultaneously. The aim of this review is, in consequence, both to evaluate the existing evidence on the association between maternal metabolic disorders, defined as obesity, diabetes, hypertension, preeclampsia, dyslipidaemia and CHDs in the offspring, as well as the significance of combinations, such as metabolic syndrome, as risk factors.

METHODS

A systematic literature search of papers published between January 1, 1990 and January 14, 2021 was conducted using PubMed and Embase. Studies were eligible if they were published in English and were case-control or cohort studies. The exposures of interest were maternal overweight or obesity, hypertension, preeclampsia, diabetes, dyslipidaemia, and/or metabolic syndrome, and the outcome of interest was CHDs in the offspring. Furthermore, the studies were included according to a quality assessment score.

RESULTS

Of the 2,250 identified studies, 32 qualified for inclusion. All but one study investigated only the individual metabolic disorders. Some disorders (obesity, gestational diabetes, and hypertension) increased risk of CHDs marginally whereas pre-gestational diabetes and early-onset preeclampsia were strongly associated with CHDs, without consistent differences between CHD subtypes. A single study suggested a possible additive effect of maternal obesity and gestational diabetes.

CONCLUSIONS

Future studies of the role of aberrations of the glucose-insulin homeostasis in the common aetiology and mechanisms of metabolic disorders, present during pregnancy, and their association, both as single conditions and-particularly-in combination, with CHDs are needed.

Flutamide induces uterus and ovary damage in the mouse via apoptosis and excessive autophagy of cells following triggering of the unfolded protein response

Intrauterine exposure to flutamide not only causes abnormal development of the reproductive organs in male offspring, but also damages ovaries and uteri. The unfolded protein response (UPR) is believed to play an important role in embryo development and teratogenic processes. In the present study, pregnant mice were administered either flutamide (300mg kg-1 day-1, p.o.) on an equivalent volume of soybean oil (control) on Days 12-18 of gestation. Eight weeks after birth, female offspring in the flutamide-treated group had a lower bodyweight and lower ovarian and uterine weights, but there was no significant difference in uterine and ovarian weights normalised by bodyweight between the flutamide-treated and control groups. Furthermore, histopathological changes were observed in all uteri and ovaries in the flutamide-treated group, with fewer and less-developed follicles in the ovaries. In both the uteri and ovaries, flutamide increased the expression of UPR members, although the expression of cell cycle-related genes remained unchanged compared with the control group. Flutamide increased the expression of all autophagy- and apoptosis-related genes evaluated in the uterus, as well as some in the ovary. The results suggest that the in utero exposure of mice to flutamide may contribute to uterine and ovarian damage in the offspring, with endoplasmic reticulum stress possibly triggered by the UPR leading to the induction of excessive autophagy and apoptosis.

Maternal obesity persistently alters cardiac progenitor gene expression and programs adult-onset heart disease susceptibility

Objective

Heart disease risk can be programmed by intrauterine exposure to obesity. Dysregulating key transcription factors in cardiac progenitors can cause subsequent adult-onset heart disease. In this study, we investigated the transcriptional pathways that are altered in the embryonic heart and linked to heart disease risk in offspring exposed to obesity during pregnancy.

Methods

Female mice were fed an obesogenic diet and mated with males fed a control diet. Heart function and genome-wide gene expression were analyzed in adult offspring born to obese and lean mice at baseline and in response to stress. Cross-referencing with genes dysregulated genome-wide in cardiac progenitors from embryos of obese mice and human fetal hearts revealed the transcriptional events associated with adult-onset heart disease susceptibility.

Results

We found that adult mice born to obese mothers develop mild heart dysfunction consistent with early stages of disease. Accordingly, hearts of these mice dysregulated genes controlling extracellular matrix remodeling, metabolism, and TGF-β signaling, known to control heart disease progression. These pathways were already dysregulated in cardiac progenitors in embryos of obese mice. Moreover, in response to cardiovascular stress, the heart of adults born to obese dams developed exacerbated myocardial remodeling and excessively activated regulators of cell-extracellular matrix interactions but failed to activate metabolic regulators. Expression of developmentally regulated genes was altered in cardiac progenitors of embryos of obese mice and human hearts of fetuses of obese donors. Accordingly, the levels of Nkx2-5, a key regulator of heart development, inversely correlated with maternal body weight in mice. Furthermore, Nkx2-5 target genes were dysregulated in cardiac progenitors and persistently in adult hearts born to obese mice and human hearts from pregnancies affected by obesity.

Conclusions

Obesity during pregnancy alters Nkx2-5-controlled transcription in differentiating cardiac progenitors and persistently in the adult heart, making the adult heart vulnerable to dysregulated stress responses.

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Maternal obesity programs progressive heart dysfunction in adult offspring.

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Offspring of obese dams are prone to dysregulated stress responses in the heart.

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Nkx2-5-controlled transcription is dysregulated in hearts exposed to obesity in utero.

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Obesity during pregnancy broadly affects gene expression in the embryonic heart.

Baicalin rescues hyperglycemia-induced neural tube defects via targeting on retinoic acid signaling

We, in this study, studied whether or not antioxidant activities of Baicalin could reduce the incidence of neural tube defects (NTDs) in the presence of hyperglycemia. Using early chick embryos, we demonstrated that Baicalin at 6 μM dramatically reduced NTDs rate and impaired neurogenesis in E4.5-day and HH10 chick embryo neural tubes induced by high glucose (HG). Likewise, immunofluorescent staining showed that Baicalin mitigated the HG-induced regression of Pax7 expression in neural tubes of both HH10 and E4.5-day chick embryos. Additionally, PHIS3 immunofluorescent staining in neural tubes of both HH10 and E4.5-day chick embryos manifested that cell proliferation inhibited by HG was significantly reversed by the administration of Baicalin, and similar result could also be observed in neurosphere assay in vitro. c-Caspase3 or γH2AX immunofluorescent staining and quantitative PCR showed that Baicalin administration alleviated HG-induced cell apoptosis and DNA damage. Bioinformatics results indicated that retinoic acid (RA) was likely to be the signaling pathway that Baicalin targeted on, and this was confirmed by whole-mount RALDH2 in situ hybridization and quantitative PCR of HH10 chick embryos in the absence/presence of Baicalin. In addition, blocking RA with an inhibitor abolished Baicalin's protective role in HG-induced NTDs, suppression of neurogenesis and cell proliferation, and induction of apoptosis, which further verified the centrality of RA in the process of Baicalin confronting HG-induced abnormal neurodevelopment.

Role of unfolded protein response in genital malformation/damage of male mice induced by flutamide

The unfolded protein response (UPR) is one of a switch of autophagy and apoptosis, and the endoplasmic reticulum stress (ERS) which inducing UPR plays a role in the malformations caused by some genetic and environmental factors. Exposure to flutamide during pregnancy will also cause abnormalities in some male offspring reproductive organs such as cryptorchidism. In this study, after administered the pregnant mouse orally at a dose of 300 mg/kg body weight every day during gestational day (GD)12 to GD18, flutamide can not only caused hypospadias in the male mouse offspring but also damaged the morphology and function of their testis. And the expression of UPR-related genes and proteins, autophagy, apoptosis, and angiogenesis-related genes of the damaged/teratogenic testis and penis in the mice were investigated to determine the role of UPR in this model. It was found that flutamide activated maybe the Atg7-Atg3-Lc3 pathway through the UPR pathway, caused cells excessive autophagy and apoptosis, and inhibited the formation of penile and testicular blood vessels by activating UPR and affecting the messenger RNA level of vascular endothelial growth factor and hypoxia-inducible factor 1.

Zinc oxide nanoparticles exposure-induced oxidative stress restricts cranial neural crest development during chicken embryogenesis

Zinc oxide Nanoparticles (ZnO NPs) are widely used as emerging materials in agricultural and food-related fields, which exists potential safety hazards to public health and environment while bringing an added level of convenience to our original life. It has been proved that ZnO NPs could be taken up by pregnant women and passed through human placental barrier. However, the toxic potential for embryo development remains largely unanswered. In this study, we discovered that ZnO NPs caused the cytotoxicity in vitro. Inhibition of free Zn²⁺ ions in solution by EDTA or inhibition of Zn²⁺ ions absorption by CaCl₂ could partially eliminate ZnO NPs-mediated cell toxicity, though not redeem completely. This indicated that both nanoparticles and the release of Zn²⁺ ions were involved in ZnO NPs-mediated cytotoxicity. In addition, we also found that both nanoparticles and Zn²⁺ ion release triggered reactive oxygen species (ROS) production, which further induced cell toxicity, inflammation and apoptosis, which are mediated by NF-κB signaling cascades and the mitochondria dysfunction, respectively. Eventually, these events lead to the suppressed production and migration of cranial neural crest cells (CNCCs), which subsequently prompts the craniofacial defects in chicken embryos. The application of the antioxidant N-Acetyl-L-cysteine (NAC) rescued the ZnO NPs-induced cell toxicity and malformation of the CNCCs, which further verified our hypothesis. Our results revealed the relevant mechanism of ZnO NPs exposure-inhibited the development of CNCCs, which absolutely contribute to assess the risk of nanoparticles application.

Maternal Obesity and Diabetes Mellitus as Risk Factors for Congenital Heart Disease in the Offspring

Congenital heart disease (CHD) is the most common anatomical malformation occurring live‐born infants and an increasing cause of morbidity and mortality across the lifespan and throughout the world. Population‐based observations have long described associations between maternal cardiometabolic disorders and the risk of CHD in the offspring. Here we review the epidemiological evidence and clinical observations relating maternal obesity and diabetes mellitus to the risk of CHD offspring with particular attention to mechanistic models of maternal‐fetal risk transmission and first trimester disturbances of fetal cardiac development. A deeper understanding of maternal risk factors holds the potential to improve both prenatal detection of CHD by identifying at‐risk pregnancies, along with primary prevention of disease by improving preconception and prenatal treatment of at‐risk mothers.

Aberrant regulation of autophagy in mammalian diseases

Autophagy is a major cellular metabolic pathway that facilitates degradation of a subset of long-lived proteins and cytoplasmic organelles in eukaryotic cells. This pathway plays a vital role in preserving the cellular homeostasis of the cells themselves, in addition to maintaining the normal physiological state of cell renewal. Many stressors, such as starvation, ischaemia and oxidative stress can induce autophagy. In addition to its physiological roles, autophagy also occurs in a wide variety of pathological processes, including tumour progression, metabolic disorders, and neurodegenerative and lung diseases. In recent years, a growing body of evidence has shown that autophagy also plays a key role in the development of mammalian diseases, a function that has garnered substantial attention and study. An in-depth understanding of the molecular role that autophagy plays in pathological settings is vital for both the diagnosis and treatment of mammalian diseases and will aid in the search for novel targets for therapeutic drug intervention. Here, we provide an integrated review of recent studies implicating autophagy dysfunction in the progression of mammalian disorders and summarize research suggesting that the molecular pathways involved in autophagy could serve as potential therapeutic targets.

Baicalin administration attenuates hyperglycemia-induced malformation of cardiovascular system

In this study, the effects of Baicalin on the hyperglycemia-induced cardiovascular malformation during embryo development were investigated. Using early chick embryos, an optimal concentration of Baicalin (6 μM) was identified which could prevent hyperglycemia-induced cardiovascular malformation of embryos. Hyperglycemia-enhanced cell apoptosis was reduced in embryos and HUVECs in the presence of Baicalin. Hyperglycemia-induced excessive ROS production was inhibited when Baicalin was administered. Analyses of SOD, GSH-Px, MQAE and GABAA suggested Baicalin plays an antioxidant role in chick embryos possibly through suppression of outwardly rectifying Cl(−) in the high-glucose microenvironment. In addition, hyperglycemia-enhanced autophagy fell in the presence of Baicalin, through affecting the ubiquitin of p62 and accelerating autophagy flux. Both Baicalin and Vitamin C could decrease apoptosis, but CQ did not, suggesting autophagy to be a protective function on the cell survival. In mice, Baicalin reduced the elevated blood glucose level caused by streptozotocin (STZ). Taken together, these data suggest that hyperglycemia-induced embryonic cardiovascular malformation can be attenuated by Baicalin administration through suppressing the excessive production of ROS and autophagy. Baicalin could be a potential candidate drug for women suffering from gestational diabetes mellitus.

Ethanol exposure leads to disorder of blood island formation in early chick embryo

Ethanol's effect on embryonic vasculogenesis and its underlying mechanism is obscure. Using VE-cadherin in situ hybridization, we found blood islands formation was inhibited in area opaca, but abnormal VE-cadherin⁺ cells were seen in area pellucida. We hypothesise ethanol may affect blood island progenitor cell migration and differentiation. DiI and in vitro experiments revealed ethanol inhibited cell migration, Quantitative PCR analysis revealed that ethanol exposure enhanced cell differentiation in area pellucida of HH5 chick embryos and repressed cell differentiation in area pellucida of HH8 chick embryos. By exposing to 2,2'-azobis-amidinopropane dihydrochloride, a ROS inducer, which gave a similar anti-vasculogenesis effect as ethanol and this anti-vasculogenesis effect could be reversed by vitamin C. Overall, exposing early chick embryos to ethanol represses blood island progenitor cell migration but disturbed differentiation at a different stage, so that the disorder of blood island formation occurs through excess ROS production and altered vascular-associated gene expression.

Autophagy is involved in ethanol-induced cardia bifida during chick cardiogenesis

Excess alcohol consumption during pregnancy has been acknowledged to increase the incidence of congenital disorders, especially the cardiovascular system. However, the mechanism involved in ethanol-induced cardiac malformation in prenatal fetus is still unknown. We demonstrated that ethanol exposure during gastrulation in the chick embryo increased the incidence of cardia bifida. Previously, we reported that autophagy was involved in heart tube formation. In this context, we demonstrated that ethanol exposure increased ATG7 and LC3 expression. mTOR was found to be inhibited by ethanol exposure. We activated autophagy using exogenous rapamycin (RAPA) and observed that it induced cardiac bifida and increased GATA5 expression. RAPA beads implantation experiments revealed that RAPA restricted ventricular myosin heavy chain (VMHC) expression. In vitro explant cultures of anterior primitive streak demonstrated that both ethanol and RAPA treatments could reduce cell differentiation and the spontaneous beating of cardiac precursor cells. In addition, the bead experiments showed that RAPA inhibited GATA5 expression during heart tube formation. Semiquantitative RT-PCR analysis indicated that BMP2 expression was increased while GATA4 expression was suppressed. In the embryos exposed to excess ethanol, BMP2, GATA4 and FGF8 expression was repressed. These genes are associated with cardiomyocyte differentiation, while heart tube fusion is associated with increased Wnt3a but reduced VEGF and Slit2 expression. Furthermore, the ethanol exposure also caused the production of excess ROS, which might damage the cardiac precursor cells of developing embryos. In sum, our results revealed that disrupting autophagy and excess ROS generation are responsible for inducing abnormal cardiogenesis in ethanol-treated chick embryos.

Therapeutic targeting of autophagy in myocardial infarction and heart failure

INTRODUCTION

Myocardial infarction (MI) is the leading cause of death. When MI is not lethal, heart failure (HF) is a major consequence with high prevalence and poor prognosis. The targeting of autophagy represents a potentially therapeutic approach for the treatment of both pathologies.

AREAS COVERED

PubMed searches were performed to discuss the current state of the art regarding the role of autophagy in MI and HF. We review available and potential approaches to modulate autophagy from a pharmacological and genetic perspective. We also discuss the targeting of autophagy in myocardial regeneration. Expert commentary: The targeting of autophagy has potential for the treatment of MI and HF. Autophagy is a process that takes place in virtually all cells of the body and thus, in order to evaluate this therapeutic approach in clinical trials, strategies that specifically target this process in the myocardium is required to avoid unwanted effects in other organs.

Proper autophagy is indispensable for angiogenesis during chick embryo development

People have known that autophagy plays a very important role in many physiological and pathological events. But the role of autophagy on embryonic angiogenesis still remains obscure. In this study, we demonstrated that Atg7, Atg8 and Beclin1 were expressed in the plexus vessels of angiogenesis at chick yolk sac membrane and chorioallantoic membrane. Interfering in autophagy with autophagy inducer or inhibitor could restrict the angiogenesis in vivo, which might be driven by the disorder of angiogenesis-related gene expressions, and also lead to embryonic hemorrhage, which was due to imperfection cell junctions in endothelial cells including abnormal expressions of tight junction, adheren junction and desmosome genes. Using HUVECs, we revealed that cell viability and migration ability changed with the alteration of cell autophagy exposed to RAPA or 3-MA. Interestingly, tube formation assay showed that HUVECs ability of tube formation altered with the change of Atg5, Atg7 and Atg8 manipulated by the transfection of their corresponding siRNA or plasmids. Moreover, the lost cell polarity labeled by F-actin and the absenced β-catenin in RAPA-treated and 3-MA-treated cell membrane implied intracellular cytoskeleton alteration was induced by the activation and depression of autophagy. Taken together, our current experimental data reveal that autophagy is really involved in regulating angiogenesis during embryo development.

High glucose environment inhibits cranial neural crest survival by activating excessive autophagy in the chick embryo

High glucose levels induced by maternal diabetes could lead to defects in neural crest development during embryogenesis, but the cellular mechanism is still not understood. In this study, we observed a defect in chick cranial skeleton, especially parietal bone development in the presence of high glucose levels, which is derived from cranial neural crest cells (CNCC). In early chick embryo, we found that inducing high glucose levels could inhibit the development of CNCC, however, cell proliferation was not significantly involved. Nevertheless, apoptotic CNCC increased in the presence of high levels of glucose. In addition, the expression of apoptosis and autophagy relevant genes were elevated by high glucose treatment. Next, the application of beads soaked in either an autophagy stimulator (Tunicamycin) or inhibitor (Hydroxychloroquine) functionally proved that autophagy was involved in regulating the production of CNCC in the presence of high glucose levels. Our observations suggest that the ERK pathway, rather than the mTOR pathway, most likely participates in mediating the autophagy induced by high glucose. Taken together, our observations indicated that exposure to high levels of glucose could inhibit the survival of CNCC by affecting cell apoptosis, which might result from the dysregulation of the autophagic process.

The impact of high salt exposure on cardiovascular development in the early chick embryo

In this study, we showed that high salt exposure dramatically increased chick embryonic mortality during embryo development. As embryonic mortality at early stages mainly results from defects in cardiovascular development, we focused on heart formation and angiogenesis in the following experiments. We found that high salt exposure enhanced the risk of abnormal heart tube looping and blood congestion in the heart chamber. In the presence of high salt, both ventricular cell proliferation and apoptosis increased. The high osmolarity induced by high salt in the ventricular cardiomyocytes resulted in incomplete differentiation, which might be due to reduced Nkx2.5 and GATA4 expression. Blood vessel density and diameter were suppressed by exposure to high salt in both the yolk sac membrane (YSM) and chorioallantoic membrane (CAM) models. In addition, high salt-induced suppression of angiogenesis occurred even at the vasculogenesis stage, as blood island formation was also inhibited by high salt exposure. At the same time, cell proliferation was repressed and cell apoptosis was enhanced by high salt exposure in YSM tissue. Moreover, the reduction in HIF2 and FGF2 gene expression might cause the high salt-suppressed angiogenesis. Interestingly, we showed that high salt exposure caused excess ROS generation in the heart and YSM tissues, which could be partially rescued through the addition of antioxidants. In total, our study suggested that excess ROS generation might play an important role in high-salt induced the heart and angiogenesis defects.