Silencing mouse circular RNA circSlc8a1 by circular antisense cA-circSlc8a1 induces cardiac hepatopathy.

Circular RNAs (circRNAs) are a group of non-coding RNAs with a unique circular structure generated by back-splicing. It is acknowledged that circRNAs play critical roles in cardiovascular diseases. However, functional studies of circRNAs were impeded due to lack of effective in vivo silencing approaches. Since most circRNAs are produced by protein-coding transcripts, gene editing typically affects the coding activity of the parental genes. In this study, we developed a circular antisense RNA (cA-circSlc8a1) that could silence the highly expressed circRNA circSlc8a1 in the mouse heart but not its parental Slc8a1 linear mRNA. Transgenic cA-circSlc8a1 mice developed congestive heart failure resulting in a significant increase in the body weight secondary to peripheral edema and congestive hepatopathy. To further test the role of circSlc8a1, we generated transgenic mice overexpressing circSlc8a1 and observed a protective effect of circSlc8a1 in a pressure overload model. Mechanistically, we found that circSlc8a1 translocated into mitochondria to drive ATP synthesis. While establishing a transgenic murine model for antisense-mediated circRNA silencing without interfering with the parental linear RNA, our finding revealed the essential role of circSlc8a1 in maintaining heart function and may lay the groundwork of using the circular antisense RNA as a potential gene therapy approach for cardiovascular diseases.

A Neuroligin Isoform Translated by circNlgn Contributes to Cardiac Remodeling.

[Figure: see text].

Graves' Disease in Children Presenting With Fragility Fracture: A Case Report.

Background: Adults with hyperthyroidism have been found to have decreased bone mineral density (BMD) and higher fracture risk. The most typical cause of hyperthyroidism is Graves' disease. However, there are limited studies on how hyperthyroidism affects bone metabolism and fractures in children. We describe a unique instance of a patient who initially displayed a fragility fracture and was ultimately identified with Graves' disease after biochemical evaluations. Case Summary: A 2-year-8-month-old female presented with fragility fractures three times in only 7 months. A series of examinations were performed to evaluate any possible malformations or abnormalities of bone metabolism. Graves' disease was found, and drug therapies were employed (methimazole, propranolol, calcium carbonate, vitamin D). Since children with Graves' disease and fragility fractures have been uncommonly described in the past, a stringent and thorough long-term follow-up was initiated. Conclusions: Children with undiagnosed Graves' disease had a higher risk of fractures and osteoporosis. This case suggests that BMD measurement may be necessary for the initial evaluation of Graves' disease in children.

An antisense circular RNA circSCRIB enhances cancer progression by suppressing parental gene splicing and translation.

Circular RNAs (circRNAs) represent a large group of non-coding RNAs that are widely detected in mammalian cells. Although most circRNAs are generated in a sense orientation, there is a group of circRNAs that are synthesized in an antisense orientation. High-throughput analysis of breast cancer specimens revealed a significant enrichment of 209 antisense circRNAs. The tumor suppressor SCRIB was shown to potentially produce thirteen circRNAs, three of which are in an antisense orientation. Among these three circRNAs, circSCRIB (hsa_circ_0001831) was the most enriched in the breast cancer panel. This antisense SCRIB circRNA was shown to span one intron and two exons. We hypothesized that this circRNA could decrease pre-mRNA splicing and mRNA translation. To test this, we generated a hsa_circ_0001831 expression construct. We found that there was decreased SCRIB mRNA production but increased cancer cell proliferation, migration, and invasion. In comparison, an exonic sequence construct did not affect mRNA splicing but decreased protein translation, leading to increased E-cadherin expression and decreased expression of N-cadherin and vimentin. Thus, there was increased cell migration, invasion, proliferation, colony formation, and tumorigenesis. Our study suggests a novel modulatory role of antisense circRNAs on their parental transcripts. This may represent a promising approach for developing circRNA-directed therapy.

YAP Circular RNA, circYap, Attenuates Cardiac Fibrosis via Binding with Tropomyosin-4 and Gamma-Actin Decreasing Actin Polymerization.

Cardiac fibrosis is a common pathological feature of cardiac hypertrophy. This study was designed to investigate a novel function of Yes-associated protein (YAP) circular RNA, circYap, in modulating cardiac fibrosis and the underlying mechanisms. By circular RNA sequencing, we found that three out of fifteen reported circYap isoforms were expressed in nine human heart tissues, with the isoform hsa_circ_0002320 being the highest. The levels of this isoform in the hearts of patients with cardiac hypertrophy were found to be significantly decreased. In the pressure overload mouse model, the levels of circYap were reduced in mouse hearts with transverse aortic constriction (TAC). Upon circYap plasmid injection, the cardiac fibrosis was attenuated, and the heart function was improved along with the elevation of cardiac circYap levels in TAC mice. Tropomyosin-4 (TMP4) and gamma-actin (ACTG) were identified to bind with circYap in cardiac cells and mouse heart tissues. Such bindings led to an increased TPM4 interaction with ACTG, resulting in the inhibition of actin polymerization and the following fibrosis. Collectively, our study uncovered a novel molecule that could regulate cardiac remodeling during cardiac fibrosis and implicated a new function of circular RNA. This process may be targeted for future cardio-therapy.

Segmental maternal uniparental disomy of chromosome 7q in a patient with congenital chloride diarrhea.

BACKGROUND: The main symptoms of congenital chloride diarrhea (CCD) main symptoms are watery diarrhea, hypochloremia, and hypokalemic metabolic alkalosis. Silver-Russell syndrome (SRS) is a heterogeneous imprinting disorder characterized by severe intrauterine retardation, poor postnatal growth, and facial dysmorphism. METHODS: Parent-offspring trio whole-exome sequencing was used to identify the causal variants. Sequencing reads were mapped to the reference of human genome version hg19. Sanger sequencing was performed as a confirmatory experiment. RESULTS: The proband was a patient with SRS caused by maternal uniparental disomy 7. The CCD of the proband was caused by homozygous variant c.1515-1 (IVS13) G>A; both mutated alleles were inherited from her mother. CONCLUSION: We report the first clinical case of CCD and SRS occurring together. Patients with milder phenotypes may be difficult to diagnose in early stage, but close monitoring of potential complications is important for identification.

Macrophage-mediated regulation of catecholamines in sympathetic neural remodeling after myocardial infarction.

Sympathetic neural remodeling, which involves the inflammatory response, plays an important role in ventricular arrhythmias (VAs) after myocardial infarction (MI). Adrenergic receptors on macrophages potentially modulate the inflammatory response. We hypothesized that the increased level of catecholamines activates macrophages and regulates sympathetic neural remodeling after MI. We treated MI mice with either clodronate or metoprolol for 5 days following coronary artery ligation. Mice without treatment after MI and sham-operation mice served as the positive control and negative control, respectively. The norepinephrine levels in plasma and the peri-infarct myocardium increased by almost two-fold in the MI mice compared with the sham-operation mice. Both in vivo and ex vivo electrophysiology examinations showed that the vulnerability to VAs induced by MI was alleviated by macrophage depletion with clodronate and ß1-adrenergic blockade with metoprolol, which was in line with circulating and peri-infarct norepinephrine levels, sympathetic reinnervation, and the expression of nerve growth factor (NGF) 7 days after surgery. To further verify the interaction between catecholamines and macrophages, we preconditioned lipopolysaccharide-stimulated RAW 264.7 cells using epinephrine or epinephrine with selective adrenergic antagonists. The expression and release of inflammatory factors including NGF were enhanced by epinephrine. This effect was inhibited by metoprolol but not by other subtype antagonists. Our data suggested that the increased level of catecholamines, traditionally known as positive inotropes secreted from sympathetic nerve endings, might regulate cardiac sympathetic neural remodeling through ß1-adrenergic receptors on macrophages, subsequently inducing VAs after MI.

The Circular RNA Interacts with STAT3, Increasing Its Nuclear Translocation and Wound Repair by Modulating Dnmt3a and miR-17 Function.

Delayed or impaired wound healing is a major health issue worldwide, especially in patients with diabetes and atherosclerosis. Here we show that expression of the circular RNA circ-Amotl1 accelerated healing process in a mouse excisional wound model. Further studies showed that ectopic circ-Amotl1 increased protein levels of Stat3 and Dnmt3a. The increased Dnmt3a then methylated the promoter of microRNA miR-17, decreasing miR-17-5p levels but increasing fibronectin expression. We found that Stat3, similar to Dnmt3a and fibronectin, was a target of miR-17-5p. Decreased miR-17-5p levels would increase expression of fibronectin, Dnmt3a, and Stat3. All of these led to increased cell adhesion, migration, proliferation, survival, and wound repair. Furthermore, we found that circ-Amotl1 not only increased Stat3 expression but also facilitated Stat3 nuclear translocation. Thus, the ectopic expressed circ-Amotl1 and Stat3 were mainly translocated to nucleus. In the presence of circ-Amotl1, Stat3 interacted with Dnmt3a promoter with increased affinity, facilitating Dnmt3a transcription. Ectopic application of circ-Amotl1 accelerating wound repair may shed light on skin wound healing clinically.

[Correlation between uncoupling protein 2 expression and myocardial mitochondrial injury in rats with sepsis induced by lipopolysaccharide].

OBJECTIVE: To investigate the correlation between uncoupling protein 2 (UCP2) expression and myocardial mitochondria injury in rats with sepsis induced by lipopolysaccharide (LPS). METHODS: The rat model of sepsis was established through an intraperitoneal injection of LPS. Forty male Sprague-Dawley rats were randomly and equally divided into control group (an intraperitoneal injection of normal saline), sepsis 6 h group (LPS-6 h group), sepsis 12 h group (LPS-12 h group), sepsis 24 h group (LPS-24 h group), and sepsis 48 h group (LPS-48 h group). The serum and heart tissues were harvested at corresponding time points and myocardial mitochondria was extracted. The microplate reader was applied to measure creatine kinase (CK), creatine kinase-MB (CK-MB), and reactive oxygen species (ROS). Flow cytometry was applied to measure the degree of mitochondrial swelling and mitochondrial membrane potential (MMP). Western blot was used to measure the expression level of UCP2. Electron microscopy was applied to observe the morphological changes in heart tissues and myocardial mitochondria. RESULTS: Compared with the control group, the LPS groups had significantly increased serum levels of CK, CK-MB, and myocardial ROS, as well as a significantly increased degree of mitochondrial swelling (P<0.05), and these values reached their peaks at 24 hours after LPS injection. The LPS groups had a significant decrease in MMP (P<0.05), which reached the lowest level at 24 hours after LPS injection. Western blot showed that the LPS groups had a significant increase in the expression level of myocardial UCP2 compared with the control group (P<0.05), which reached its peak at 24 hours after LPS injection. The results of electron microscopy showed mitochondrial swelling, partial rupture of the mitochondrial membrane, and cavity formation in rats in the LPS groups. The most severe lesions occurred in the LPS-24 h group. In rats with LPS, the ROS level in the myocardial mitochondria and the degree of mitochondrial swelling were positively correlated with the expression level of UCP2 (r=0.796 and 0.893, respectively; P<0.05), while MMP was negatively correlated with the expression level of UCP2 (r=-0.903, P<0.05). CONCLUSIONS: In the rat model of sepsis, the myocardium and myocardial mitochondria have obvious injuries, and the expression level of UCP2 is closely correlated with mitochondrial injury. Therefore, UCP2 might play an important role in myocardial mitochondrial injury in sepsis.

Experimental treatments for mitochondrial dysfunction in sepsis: A narrative review.

Sepsis is a systemic inflammatory response to infection. Sepsis, which can lead to severe sepsis, septic shock, and multiple organ dysfunction syndrome, is an important cause of mortality. Pathogenesis is extremely complex. In recent years, cell hypoxia caused by mitochondrial dysfunction has become a hot research field. Sepsis damages the structure and function of mitochondria, conversely, mitochondrial dysfunction aggravated sepsis. The treatment of sepsis lacks effective specific drugs. The aim of this paper is to undertake a narrative review of the current experimental treatment for mitochondrial dysfunction in sepsis. The search was conducted in PubMed databases and Web of Science databases from 1950 to January 2014. A total of 1,090 references were retrieved by the search, of which 121 researches met all the inclusion criteria were included. Articles on the relationship between sepsis and mitochondria, and drugs used for mitochondrial dysfunction in sepsis were reviewed retrospectively. The drugs were divided into four categories: (1) Drug related to mitochondrial matrix and respiratory chain, (2) drugs of mitochondrial antioxidant and free radical scavengers, (3) drugs related to mitochondrial membrane stability, (4) hormone therapy for septic mitochondria. In animal experiments, many drugs show good results. However, clinical research lacks. In future studies, the urgent need is to develop promising drugs in clinical trials.

[A preliminary study of long-term mitochondrial dysfunction in rat brain caused by lipopolysaccharide-induced sepsis].

OBJECTIVE: To preliminarily investigate the long-term structural and functional injuries of mitochondria in rat brain caused by sepsis. METHODS: Wistar rats were randomly assigned into sepsis and control groups. A rat model of sepsis was prepared by an intraperitoneal injection of 10 mg/kg lipopolysaccharide (LPS) of gram-negative bacteria, and the survival assay was performed. Eight rats in the sepsis group were sacrificed at 12, 24, 48, or 72 hours after LPS injection, while rats in the control group were sacrificed after an intraperitoneal injection of an equal volume of normal saline. Mitochondria were extracted from rat brain tissue. Mitochondrial membrane potential (MMP) and mitochondrial swelling level were determined by flow cytometry, and the activities of electron transport chain complexes (I-V) were measured using enzyme assay kits. Hematoxylin-eosin (HE) staining and electron microscopy were used to observe morphological changes in brain tissue and mitochondria. RESULTS: The sepsis group had a significantly lower survival rate than the control group (P<0.01). The MMP and activities of electron transport chain complexes (I-V) in the sepsis group, which were significantly lower than those in the control group (P<0.05), were reduced to the lowest levels at 48 hours and partially recovered at 72 hours. The mitochondrial swelling level in the sepsis group, which was significantly higher than that in the control group (P<0.05), increased to the peak level at 48 hours and partially recovered at 72 hours. Hematoxylin and Eosin staining revealed substantial damages in the structure of brain tissue, and electron microscopy showed mitochondrial swelling, and vacuolization in a few mitochondria. CONCLUSIONS: In the rat model of LPS-induced sepsis, both structural and functional injuries are found in cerebral mitochondria, and achieve the peak levels probably at around 48 hours.

Cardioprotective effects of high-altitude adaptation in cardiac surgical patients: a retrospective cohort study with propensity score matching.

Background: The cardioprotective effect of remote ischemia preconditioning in clinical studies is inconsistent with experimental results. Adaptation to high-altitude hypoxia has been reported to be cardioprotective in animal experiments. However, the clinical significance of the cardioprotective effect of high-altitude adaptation has not been demonstrated. Methods: A retrospective cohort study with propensity score matching was designed to compare the outcomes of cardiac surgery between highlanders and lowlanders in a tertiary teaching hospital. The data of adult cardiac surgical patients from January 2013 to December 2022, were collected for analysis. Patients with cardiopulmonary bypass and cardioplegia were divided into a low-altitude group (<1,500 m) and a high-altitude group (≥1,500 m) based on the altitude of their place of residence. Results: Of 3,020 patients, the majority (87.5%) permanently lived in low-altitude regions [495 (435, 688) m], and there were 379 patients (12.5%) in the high-altitude group [2,552 (1,862, 3,478) m]. The 377 highlander patients were matched with lowlander patients at a ratio of 1:1. The high-altitude group exhibited a 44.5% reduction in the incidence of major adverse cardiovascular events (MACEs) compared with the low-altitude group (6.6% vs. 11.9%, P = 0.017). The patients in the moderate high-altitude subgroup (2,500-3,500 m) had the lowest incidence (5.6%) of MACEs among the subgroups. The level of creatinine kinase muscle-brain isoenzymes on the first postoperative morning was lower in the high-altitude group than in the low-altitude group (66.5 [47.9, 89.0] U/L vs. 69.5 [49.3, 96.8] U/L, P = 0.003). Conclusions: High-altitude adaptation exhibits clinically significant cardioprotection in cardiac surgical patients.

Erratum - Transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2) ameliorates sepsis-associated acute kidney injury by maintaining mitochondrial homeostasis and improving the mitochondrial function.

This corrects the article published in European Journal of Histochemistry 2022;66:3412. doi: 10.4081/ejh.2022.3412.

An Improved Model for Circular RNA Overexpression: Using the Actin Intron Reveals High Circularization Efficiency.

Traditionally, the group 1 intron of the T4 td gene is used to generate a foreign circular sequence. However, the T4 system has been shown to be fairly inefficient in expressing circular RNA (circRNA). Here, a new method is developed to express circular sequences with high circularization efficiency to strengthen the confidence for future circRNA functional studies. CircRNA expression plasmids, constructed with different lengths derived from the actin intron (15-nt, 30-nt, 60-nt, 100-nt, 180-nt) and T4 intron, are introduced into human and mouse cell lines 293T and B16. Junction detection and sequencing are used to determine successful circularization of introns and their expression efficiencies. An actin intron with a medium length (60-nt-100-nt) shows significantly increased efficiency of circularization, whereas intron-100-nt shows the best efficiency in most conditions. RNA pull-down assays are designed to precipitate the splicing factors that are bound to the introns and intron/exon junction. The precipitated proteins are analyzed by mass spectrometry (MS), aiming to identify the possible underlying mechanism behind the high circularization efficiency. This expression system has been validated using different circRNAs, and such method shows potential in contributing to the expanding field of circRNA studies.

Transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2) ameliorates sepsis-associated acute kidney injury by maintaining mitochondrial homeostasis and improving the mitochondrial function.

Mitochondrial dysfunction has a role in sepsis-associated acute kidney injury (S-AKI), so the restoration of normal mitochondrial homeostasis may be an effective treatment strategy. Transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2) is a main regulator of cell-redox homeostasis, and recent studies reported that NRF2 activation helped to preserve mitochondrial morphology and function under conditions of stress. However, the role of NRF2 in the process of S-AKI is still not well understood. The present study investigated whether NRF2 regulates mitochondrial homeostasis and influences mitochondrial function in S-AKI. We demonstrated activation of NRF2 in an in vitro model: lipopolysaccharide (LPS) challenge of ductal epithelial cells of rat renal tubules (NRK-52e cells), and an in vivo model: cecal ligation and puncture (CLP) of rats. Over-expression of NRF2 attenuated oxidative stress, apoptosis, and the inflammatory response; enhanced mitophagy and mitochondrial biogenesis; and mitigated mitochondrial damage in the in vitro model. In vivo experiments showed that rats treated with an NRF2 agonist had higher adenosine triphosphate (ATP) levels, lower blood urea nitrogen and creatinine levels, fewer renal histopathological changes, and higher expression of mitophagy-related proteins [PTEN-induced putative kinase 1 (PINK1), parkin RBR E3 ubiquitin protein ligase (PRKN), microtubule-associated protein 1 light chain 3 II (LC3 II)] and mitochondrial biogenesis-related proteins [peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1α) and mitochondrial transcription factor A (TFAM)]. Electron microscopy of kidney tissues showed that mitochondrial damage was alleviated by treatment with an NRF2 agonist, and the opposite response occurred upon treatment with an NRF2 antagonist. Overall, our findings suggest that mitochondria have an important role in the pathogenesis of S-AKI, and that NRF2 activation restored mitochondrial homeostasis and function in the presence of this disease. This mitochondrial pathway has the potential to be a novel therapeutic target for the treatment of S-AKI.

The Changes in Bacterial Microbiome Associated with Immune Disorder in Allergic Respiratory Disease.

Allergic respiratory disease is a worldwide and increasingly prevalent health problem. Many researchers have identified complex changes in the microbiota of the respiratory and intestinal tracts in patients with allergic respiratory diseases. These affect immune response and influence the progression of disease. However, the diversity of bacterial changes in such cases make it difficult to identify a specific microorganism to target for adjustment. Recent research evidence suggests that common bacterial variations present in allergic respiratory disease are associated with immune disorders. This finding could lead to the discovery of potential therapeutic targets in cases of allergic respiratory disease. In this review, we summarize current knowledge of bacteria changes in cases of allergic respiratory disease, to identify changes commonly associated with immune disorders, and thus provide a theoretical basis for targeting therapies of allergic respiratory disease through effective modulation of key bacteria.

Case Report: Fanconi-Bickel Syndrome in a Chinese Girl With Diabetes and Severe Hypokalemia.

Fanconi-Bickel syndrome (FBS) is a rare autosomal recessive carbohydrate metabolism disorder. The main symptoms of FBS are hepatomegaly, nephropathy, postprandial hyperglycemia, fasting hypoglycemia, and growth retardation. Hypokalemia is a rare clinical feature in patients with FBS. In this study, we present a neonate suffering from FBS. She presented with hypokalemia, dysglycaemia, glycosuria, hepatomegaly, abnormality of liver function, and brain MRI. Trio whole-exome sequencing (WES) and Sanger sequencing were performed to identify the causal gene variants. A compound heterozygous mutation (NM_000340.2; p. Trp420*) of SLC2A2 was identified. Here, we report a patient with FBS in a consanguineous family with diabetes, severe hypokalemia, and other typical FBS symptoms. Patients with common clinical features may be difficult to diagnose just by phenotypes in the early stage of life, but WES could be an important tool. We also discuss the use of insulin in patients with FBS and highlight the importance of a continuous glucose monitoring system (CGMS), not only in diagnosis but also to avoid hypoglycemic events.

Lack of Macrophage Migration Inhibitory Factor Reduces Susceptibility to Ventricular Arrhythmias During the Acute Phase of Myocardial Infarction.

BACKGROUND: Macrophages are involved in inflammatory responses and play a crucial role in aggravating ventricular arrhythmias (VAs) after myocardial infarction (MI). Macrophage migration inhibitory factor (MIF) participates in inflammatory responses during acute MI. In the present study, we hypothesized that knockout (KO) of MIF may prevent VAs during the acute phase of MI by inhibiting macrophage-derived pro-inflammatory mediators. METHODS AND RESULTS: We demonstrated that MIF-KO mice in a mouse model of MI exhibited a significant decrease in susceptibility to VAs both in vivo (84.6% vs 40.7%, P < 0.05) and ex vivo (86.7% vs 40.0%, P < 0.05) at day 3 after MI compared with that in wild-type (WT) mice. Both WT and MIF-KO mice presented similar left ventricular contractility, peri-infarct myocardial fibrosis and sympathetic reinnervation, and circulating and local norepinephrine levels during the acute phase of MI. Meanwhile, MIF-KO mice had inhibited macrophage aggregation, alleviated connexin 43 (Cx43) redistribution, and reduced level of pro-inflammatory mediators, including tumor necrosis factor-α and interleukin-1ß (P < 0.05) at day 3 after MI. The differences in susceptibility to VAs, expression of pro-inflammatory mediators, and Cx43 redistribution after MI between WT and MIF-KO mice disappeared by macrophage depletion with clodronate liposomes in both groups. Furthermore, the pro-inflammatory activity of cultured peritoneal macrophages was inhibited by MIF deficiency and recovered with replenishment of exogenous MIF in vitro. CONCLUSION: In conclusion, we found that lack of MIF reduced the susceptibility to VAs in mouse heart during the acute phase of MI by inhibiting pro-inflammatory activity of macrophages and improving gap-junction and electrical remodeling.

UCP2 silencing aggravates mitochondrial dysfunction in astrocytes under septic conditions.

Uncoupling protein 2 (UCP2) plays a positive role in sepsis. However, the role of UCP2 in experimental sepsis in astrocytes remains unknown. The present study was designed to determine whether UCP2 has a protective effect in an experimental sepsis model in astrocytes asnd to clarify the mechanisms responsible for its neuroprotective effects after sepsis. An experimental astrocyte model mimicking sepsis­induced brain injury was established using lipopolysaccharide (LPS) and interferon (IFN)­Î³. Additionally, UCP2 knockdown in astrocytes was achieved by adenovirus transfection. Tumor necrosis factor (TNF)­α and interleukin (IL)­1ß activity, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS), and adenosine triphosphate (ATP) levels were assessed. The mitochondrial ultrastructure was evaluated, and the expression of UCP2 was determined by western blotting. LPS with IFN­Î³ co­stimulation increased the mRNA and protein expression levels of UCP2 in astrocytes, damaged the mitochondrial structure, and accelerated the release of TNF­α and IL­1ß, resulting in a decrease in the MMP, and the excessive generation of ROS. Moreover, sepsis also caused a reduction in ATP production. The knockdown of UCP2 exacerbated astrocyte injury and mitochondrial impairment. In conclusion, both the function and morphology of mitochondria were damaged in an experimental model of sepsis in astrocytes, and knockdown of UCP2 using shRNA exacerbated this impairment, suggesting that UCP2 has a positive effect on astrocytes as determined in an experimental sepsis model.

Upregulation of UCP2 Expression Protects against LPS-Induced Oxidative Stress and Apoptosis in Cardiomyocytes.

Uncoupling protein 2 (UCP2) has a cardioprotective role under septic conditions, but the underlying mechanism remains unclear. This study aimed at investigating the effects of UCP2 on the oxidative stress and apoptosis of cardiomyocytes induced by lipopolysaccharide (LPS). First, LPS increased UCP2 expression in cardiomyocytes in a time-dependent manner. LPS increased the production of lactate dehydrogenase (LDH), reactive oxygen species (ROS), and malondialdehyde (MDA) and decreased the level of superoxide dismutase (SOD). However, UCP2 knockdown increased the LPS-induced cardiac injury and oxidative stress. In addition, LPS damaged the mitochondrial ultrastructure and led to the disruption of mitochondrial membrane potential (MMP), as well as the release of mitochondrial cytochrome c. UCP2 knockdown aggravated mitochondrial injury and the release of mitochondrial cytochrome c. LPS increased the protein levels of Bax and cleaved-caspase-3, decreased the protein level of Bcl-2, and upregulated the protein level of mitogen-activated protein kinase. However, upon UCP2 knockdown, the protein levels of Bax and cleaved-caspase-3 increased even further, and the protein level of Bcl-2 was further decreased. The protein level of phosphorylated p38 was also further enhanced. Thus, UCP2 protects against LPS-induced oxidative stress and apoptosis in cardiomyocytes.