Protective effect of RIPK1-inhibitory compound in in vivo models for retinal degenerative disease.

Receptor interacting protein kinase 1 (RIPK1) plays a key role in necroptosis, which is a type of programmed necrosis that is involved in ocular diseases, including glaucoma and dry age-related macular degeneration (AMD). We previously introduced RIPK1-inhibitory compound (RIC), which has biochemical characteristics and a mode of action that are distinct from those of the prototype RIPK1 inhibitor necrostatin-1. The intraperitoneal administration of RIC exerts a protective effect on retinal ganglion cells against a glaucomatous insult. In this study, we examined the protective effect of RIC on retinal pigment epithelium (RPE) against sodium iodate (SI) insult, which is associated with dry AMD pathogenesis. The eye drop administration of RIC that reached on the retina prevented RPE loss in SI-induced retinal degeneration. RIC consistently demonstrated retinal protection in the funduscopy and electroretinogram analyses in SI-injected rabbits and iodoacetic acid-treated mini-pigs. Moreover, the in vivo protective effects of RIC were superior to those of ACU-4429 and doxycycline, which are other medications investigated in clinical trials for the treatment of dry AMD, and RIC did not induce retinal toxicity following topical administration in rats. Collectively, RIC displayed excellent retinal penetration and prevented retinal degeneration in the pathogenesis of dry AMD with a high in vivo efficacy.

Vibrio vulnificus VvpE Stimulates IL-1ß Production by the Hypomethylation of the IL-1ß Promoter and NF-κB Activation via Lipid Raft-Dependent ANXA2 Recruitment and Reactive Oxygen Species Signaling in Intestinal Epithelial Cells.

An inflammatory response is a hallmark of necrosis evoked by bacterial pathogens. Vibrio vulnificus, VvpE, is an elastase that is responsible for tissue necrosis and inflammation; however, the molecular mechanism by which it regulates host cell death has not been characterized. In the present study, we investigate the cellular mechanism of VvpE with regard to host cell death and the inflammatory response of human intestinal epithelial (INT-407) cells. The recombinant protein (r)VvpE (50 pg/ml) caused cytotoxicity mainly via necrosis coupled with IL-1ß production. The necrotic cell death induced by rVvpE is highly susceptible to the knockdown of annexin A (ANXA)2 and the sequestration of membrane cholesterol. We found that rVvpE induces the recruitment of NADPH oxidase 2 and neutrophil cytosolic factor 1 into membrane lipid rafts coupled with ANXA2 to facilitate the production of reactive oxygen species (ROS). The bacterial signaling of rVvpE through ROS production is uniquely mediated by the phosphorylation of redox-sensitive transcription factor NF-κB. The silencing of NF-κB inhibited IL-1ß production during necrosis. rVvpE induced hypomethylation and region-specific transcriptional occupancy by NF-κB in the IL-1ß promoter and has the ability to induce pyroptosis via NOD-, LRR-, and pyrin domain-containing 3 inflammasome. In a mouse model of V. vulnificus infection, the mutation of the vvpE gene from V. vulnificus negated the proinflammatory responses and maintained the physiological levels of the proliferation and migration of enterocytes. These results demonstrate that VvpE induces the hypomethylation of the IL-1ß promoter and the transcriptional regulation of NF-κB through lipid raft-dependent ANXA2 recruitment and ROS signaling to promote IL-1ß production in intestinal epithelial cells.

Silencing of MUC8 by siRNA increases P2Y2-induced airway inflammation.

Mucin hypersecretion and overproduction are frequent manifestations of respiratory disease. Determining the physiological function of airway mucin is presently considered more important than identifying the relevant signaling pathways. The lack of a full-length human mucin 8 (MUC8) cDNA sequence has hindered the generation of a Muc8 knockout mouse line. Thus, the precise physiological functions of MUC8 are unclear. Herein, we investigated the function of MUC8 using a small-interfering RNA (siRNA)-mediated genetic silencing approach in human airway epithelial cells. Herein, intracellular IL-1α production was stimulated by an ATP/P2Y2 complex. While ATP/P2Y2 increased IL-1α secretion in a time-dependent manner, treatment with P2Y2-specific siRNA significantly decreased IL-1α secretion. Moreover, ATP increased P2Y2-mediated upregulation of MUC8 expression; however, IL-1α significantly decreased the extent to which ATP/P2Y2 upregulated MUC8 expression. Interestingly, treatment with MUC8-specific siRNA decreased the production of anti-inflammatory cytokines (TGF-ß and IL-1 receptor antagonist) and increased the production of inflammatory cytokines (IL-1α and IL-6) in our system. In addition, siRNA-mediated knockdown of MUC8 expression dramatically increased the secretion of inflammatory chemokines and resulted in an approximately threefold decrease in cell chemotaxis. We propose that MUC8 may function as an anti-inflammatory mucin that participates in inflammatory response by attracting immune cells/cytokines to the site of inflammation. Our results provide new insight into the physiological function of MUC8 and enhance our understanding of mucin overproduction during airway inflammation.

Progerinin, an Inhibitor of Progerin, Alleviates Cardiac Abnormalities in a Model Mouse of Hutchinson-Gilford Progeria Syndrome.

Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare human premature aging disorder that precipitates death because of cardiac disease. Almost all cases of HGPS are caused by aberrant splicing of the LMNA gene that results in the production of a mutant Lamin A protein termed progerin. In our previous study, treatment with Progerinin has been shown to reduce progerin expression and improve aging phenotypes in vitro and in vivo HGPS models. In this record, cardiac parameters (stroke volume (SV), ejection fraction (EF), fractional shortening (FS), etc.) were acquired in LmnaWT/WT and LmnaG609G/WT mice fed with either a vehicle diet or a Progerinin diet by echocardiography (from 38 weeks to 50 weeks at various ages), and then the cardiac function was analyzed. We also acquired the tissue samples and blood serum of LmnaWT/WT and LmnaG609G/WT mice for pathological analysis at the end of echocardiography. From these data, we suggest that the administration of Progerinin in the HGPS model mouse can restore cardiac function and correct arterial abnormalities. These observations provide encouraging evidence for the efficacy of Progerinin for cardiac dysfunction in HGPS.

Ethical problems experienced by psychiatric nurses in Korea.

This study aimed to explore the ethical problems experienced by psychiatric nurses in a clinical setting. Data were collected using semistructured interviews with a purposive sample of 12 female psychiatric nurses from 3 psychiatric facilities in Korea. A thematic content analysis was used to identify ethical problems. The study illustrated 5 categories of ethical problems: moral unpreparedness and blindness, moral numbness, moral complacency, moral conflict, and moral stress. This study provides a theoretical basis of psychiatric ethical problems for developing ethical guidelines that will enable psychiatric nurses to make decisions reasonably and behave ethically in their workplace.

Toward Global Harmonization of Training and Certification of Specialists in Laboratory Animal Veterinary Medicine.

Laboratory animal medicine (LAM) is a corner stone of animal-based research and has been a veterinary specialty for over 60 y. Today 5 Colleges of LAM (American, European, Japanese, Korean, and Indian) that certify specialists (Diplomates) in LAM are members of the International Association of Colleges of LAM (IACLAM). Goals of IACLAM are to support the development of new Colleges of LAM, to harmonize expectations for the knowledge and skills of newly certified LAM Diplomate, and to harmonize the standards (best practices) for training and examination of candidates among the member Colleges. IACLAM recently conducted an in-depth review and comparison of oversight, training, credentialing, and examination standards in the 5 Colleges as part of an initiative to create a framework for harmonization and consistency for these activities across the 5 Colleges. The process has led to an agreement on recommendations for knowledge and skill requirements for a newly certified Diplomate, as described by each College in a detailed role delineation document (RDD). The RDD is based on task analyses of the work responsibilities of laboratory animal veterinary Diplomates. This agreement is an important step toward the goal of global harmonization of LAM Diplomate training. Further efforts are planned for areas such as training, research, publication, and examination. This paper describes the role and content of the RDD and lists the differences and similarities among the RDDs of 5 Colleges of LAM.

Peroxiredoxin 3 deficiency induces cardiac hypertrophy and dysfunction by impaired mitochondrial quality control.

Mitochondrial quality control (MQC) consists of multiple processes: the prevention of mitochondrial oxidative damage, the elimination of damaged mitochondria via mitophagy and mitochondrial fusion and fission. Several studies proved that MQC impairment causes a plethora of pathological conditions including cardiovascular diseases. However, the precise molecular mechanism by which MQC reverses mitochondrial dysfunction, especially in the heart, is unclear. The mitochondria-specific peroxidase Peroxiredoxin 3 (Prdx3) plays a protective role against mitochondrial dysfunction by removing mitochondrial reactive oxygen species. Therefore, we investigated whether Prdx3-deficiency directly leads to heart failure via mitochondrial dysfunction. Fifty-two-week-old Prdx3-deficient mice exhibited cardiac hypertrophy and dysfunction with giant and damaged mitochondria. Mitophagy was markedly suppressed in the hearts of Prdx3-deficient mice compared to the findings in wild-type and Pink1-deficient mice despite the increased mitochondrial damage induced by Prdx3 deficiency. Under conditions inducing mitophagy, we identified that the damaged mitochondrial accumulation of PINK1 was completely inhibited by the ablation of Prdx3. We propose that Prdx3 interacts with the N-terminus of PINK1, thereby protecting PINK1 from proteolytic cleavage in damaged mitochondria undergoing mitophagy. Our results provide evidence of a direct association between MQC dysfunction and cardiac function. The dual function of Prdx3 in mitophagy regulation and mitochondrial oxidative stress elimination further clarifies the mechanism of MQC in vivo and thereby provides new insights into developing a therapeutic strategy for mitochondria-related cardiovascular diseases such as heart failure.

Multivessel versus single vessel spasm, as assessed by the intracoronary acetylcholine provocation test, in Korean patients.

1. Coronary artery spasm (CAS) is known to be a major cause of myocardial ischaemia. Multivessel coronary spasm (MVS) in particular is likely to induce more severe and prolonged myocardial ischaemia than single vessel spasm (SVS). 2. In the present study, a total of 1082 consecutive patients without significant coronary artery disease who underwent an acetylcholine (ACh) provocation test between March 2004 and April 2009 were investigated. Patients were divided into three groups: an MVS group (n = 275), an SVS group (n = 376) and a non-CAS group (n = 431). Differences in clinical and angiographic characteristics following the ACh provocation test were evaluated between the MVS, SVS and non-CAS groups. 3. At baseline, patients in the MVS group had the highest prevalence of peripheral artery disease (PAD), hyperlipidaemia, smoking and old age, as well as the highest triglyceride levels. Calcium channel blockers were most frequently prescribed in MVS patients before the ACh test. During the ACh test, the highest prevalence of chest pain, ischaemic electrocardiogram changes, baseline spasms and diffuse and severe spasms were observed in the MVS group. The response rate to lower ACh doses that induce CAS was also higher in the MVS group. Multivariate analysis showed that the presence of PAD (odds ratio (OR) 2.0; P = 0.006) and baseline spasm (OR 1.4; P = 0.045) were independent predictors of ACh-induced MVS. 4. In conclusion, ischaemic symptoms, diffuse and severe spasm and baseline spasm were more frequently associated with MVS patients, suggesting more intensive medical therapies and close clinical follow up would be required for this patient group.

The effects of sling exercise program on balance and body activities in children with spastic cerebral palsy.

The purpose of this study was to investigate the static and dynamic balance and body activities after administering a trunk stability exercise program using a sling for children with spastic cerebral palsy of Gross Motor Function Classification System (GMFCS) levels III-IV. This study was conducted based on a quasi-experimental study design. Six of the study participants were assigned to the control group and six were assigned to the experimental group using simple random sampling. Both groups underwent a double-blind clinical trial study in which exercise therapy was performed for 40 min twice a week for 8 weeks. The experimental group underwent the sling exercise program and the control group underwent neuro-developmental treatment. The results showed that static and dynamic balance were significantly different before and after intervention in both the experimental and control groups (P<0.05), and there was also a statistically significant difference between the two groups (P<0.05). Gross motor function and activities of daily life showed significant improvement before and after intervention in the experimental group (P<0.05), but there was no statistically significant difference in the control group (P<0.05). There was a statistically significant difference between the two groups (P<0.05). Therefore, the sling exercise program can be used as an effective treatment for improving balance and physical activity in children with cerebral palsy of GMFCS levels III-IV who have difficulty walking. In addition, such exercise will have a positive impact on the independence of such children and help them to participate in social activities.

Combined application of rapamycin and atorvastatin improves lipid metabolism in apolipoprotein E-deficient mice with chronic kidney disease.

Atherosclerosis arising from the pro-inflammatory conditions associated with chronic kidney disease (CKD) increases major cardiovascular morbidity and mortality. Rapamycin (RAPA) is known to inhibit atherosclerosis under CKD and non-CKD conditions, but it can cause dyslipidemia; thus, the co-application of lipid-lowering agents is recommended. Atorvastatin (ATV) has been widely used to reduce serum lipids levels, but its synergistic effect with RAPA in CKD remains unclear. Here, we analyzed the effect of their combined treatment on atherosclerosis stimulated by CKD in apolipoprotein E-deficient (ApoE-/-) mice. Oil Red O staining revealed that treatment with RAPA and RAPA＋ ATV, but not ATV alone, significantly decreased the atherosclerotic lesions in the aorta and aortic sinus, compared to those seen in the control (CKD) group. The co-administration of RAPA and ATV improved the serum lipid profile and raised the expression levels of proteins involved in reverse cholesterol transport (LXRα, CYP7A1, ABCG1, PPARγ, ApoA1) in the liver. The CKD group showed increased levels of various genes encoding atherosclerosispromoting cytokines in the spleen (Tnf-α, Il-6 and Il-1ß) and aorta (Tnf-α and Il-4), and these increases were attenuated by RAPA treatment. ATV and RAPA＋ATV decreased the levels of Tnf-α and Il-1ß in the spleen, but not in the aorta. Together, these results indicate that, in CKD-induced ApoE-/- mice, RAPA significantly reduces the development of atherosclerosis by regulating the expression of inflammatory cytokines and the co-application of ATV improves lipid metabolism. [BMB Reports 2021; 54(3): 170-175].

Allogeneic renal graft rejection in a rat model: in vivo MR imaging of the homing trait of macrophages.

PURPOSE: To evaluate the feasibility of MR imaging to depict the in vivo recruitment of superparamagnetic iron oxide (SPIO)-labeled macrophages and to aid diagnosis of graft rejection in kidney transplantation. MATERIALS AND METHODS: This study was approved by the institution's committee on animal research. Eighteen male Lewis rats received a kidney transplant; 12 had an F344 rat donor and six had a Lewis rat donor. Peritoneal macrophages were harvested from thioglycollate-treated Lewis rats, cultured, and labeled with SPIO. After resuspension of macrophages in a concentration of 1 x 10(7) cells per milliliter of Hanks balanced salt solution, 5 x 10(6) of SPIO-labeled macrophages was administered through the tail vein 2 or 5 days after transplantation in each group. The transplanted kidneys were imaged on a 4.7-T MR imager 24 hours after macrophage administration. The Wilcoxon signed rank test was performed for evaluating the differences between the relative signal intensity (SI) before and after SPIO-labeled macrophage administration. RESULTS: A low-SI zone was predominantly noted in the medulla of the transplanted kidneys, and the relative SI decreased significantly from 1.40 to 0.53 (P < .001) in the allogeneic transplants following SPIO-labeled macrophage administration 5 days after the allogeneic transplantation. In the syngeneic group, the lower-SI zone was not noted in the grafts. At histopathologic examination, the lower-SI zone corresponded to the distribution of the SPIO-labeled macrophages. CONCLUSION: This study demonstrates that the homing of intravenously administered SPIO-labeled macrophages can be monitored in the allograft rejection model on in vivo MR images.

IS6110-restriction fragment length polymorphism and spoligotyping analysis of Mycobacterium tuberculosis clinical isolates for investigating epidemiologic distribution in Korea.

The Beijing family of Mycobacterium tuberculosis has been emerging in the world. However, there are few nationwide data of genotypic distribution in Korea. This study aimed to identify the genotypic diversity of clinical isolates of M. tuberculosis and to demonstrate the population of Beijing family in Korea. We collected 96 clinical M. tuberculosis isolates from 11 university hospitals nationwide in Korea from 2008 to 2009. We observed 24 clusters in IS6110-RFLP analysis and 19 patterns in spoligotyping. Seventy-five isolates were confirmed to be Beijing family. Two isolates of the K strain and 12 isolates of the K family strain were also found. We found that drug resistance phenotypes were more strongly associated with Beijing family than non-Beijing family (P=0.003). This study gives an overview of the distribution of genotypes of M. tuberculosis in Korea. These findings indicate that we have to pay more attention to control of M. tuberculosis strains associated with the Beijing family.

CD137 Signaling Regulates Acute Colitis via RALDH2-Expressing CD11b-CD103+ DCs.

CD137, a potent costimulatory receptor for CD8+ T cells, is expressed in various non-T cells, but little is known about its regulatory functions in these cells. In this study, we show that CD137 signaling, specifically in intestinal CD11b-CD103+ dendritic cells (DCs), restricts acute colitis progression. Mechanistically, CD137 engagement activates TAK1 and subsequently stimulates the AMPK-PGC-1α axis to enhance expression of the Aldh1a2 gene encoding the retinoic acid (RA) metabolizing enzyme RALDH2. RA can act on CD11b+CD103- DCs and induce SOCS3 expression, which, in turn, suppresses p38MAPK activation and interleukin-23 (IL-23) production. Administration of RA in DC-specific CD137-/- mice represses IL-23-producing CD11b+CD103- DCs and TH17 cells, indicating that RA is a major inhibitory effector molecule against intestinal CD11b+CD103- DCs. Additionally, the therapeutic effect of the anti-CD137 antibody is abrogated in DC-specific CD137-/- mice. Taken together, our results define a mechanism of paracrine immunoregulation operating between adjacent DC subsets in the intestine.

ß2-Adrenergic receptor (ß2-AR) agonist formoterol suppresses differentiation of L6 myogenic cells by blocking PI3K-AKT pathway.

ß2-Adrenergic receptor (ß2-AR) is implicated in muscle metabolic activities such as glycogen metabolism, glucose uptake, lipolysis and muscle growth. However, the functional role of ß2-AR in the differentiation of skeletal muscle is largely unknown. Here, we examined the functional role of ß2-AR in L6 myoblast differentiation using the long-term-acting ß2-AR-specific agonist formoterol. We observed that formoterol treatment strongly suppressed L6 myoblast differentiation and the expression of myosin heavy chain (MHC) in a dose- and time-dependent manner. Showing that both long-acting agonist (formoterol) and short-acting agonist (terbutaline) inhibited the induction of MHC protein, whereas ß2-AR antagonist (ICI-118,551) upregulated MHC expression, we clearly demonstrated that ß2-AR is involved in L6 myoblast differentiation. Furthermore, our pharmacological inhibition study revealed that the PI3K-AKT pathway is the main signaling pathway for myotube formation. Formoterol inhibited the activation of PI3K-AKT signaling, but not that of ERK signaling. Moreover, formoterol selectively inhibited AKT activation by IGF-I, but not by insulin. Collectively, our findings reveal a previously undocumented role of ß2-AR activation in modulating the differentiation of L6 myoblasts.

A DNA chip-based spoligotyping method for the strain identification of Mycobacterium tuberculosis isolates.

The clinical efficacy of a spoligotyping method for discriminating Mycobacterium tuberculosis strains was evaluated. Among the strains other than Beijing or Beijing like family, 30 different spoligotypes out of 39 strains were produced, which included 4 strains not having IS6110 sequence. The oligonucleotide chip-based spoligotyping technique is useful for early screening and detection of clonal proximity of M. tuberculosis isolates.

In Vitro Investigation of Wear of CAD/CAM Polymeric Materials Against Primary Teeth.

The aim of the study was to evaluate the effects of polymeric computer-aided design/computer-aided manufacturing CAD/CAM materials on antagonistic primary tooth wear. Five CAD/CAM polymeric materials were examined: Vipi Block Monocolor (VBM), Yamahachi polymethylmethacrylate (PMMA) (YAP), Mazic Duro (MZD), Vita Enamic (ENA), and Pekkton (PEK). All of the specimens were tested in a thermomechanical loading machine with the primary canine as the antagonist (50 N, 1.2 × 105 cycles, 1.7 Hz, 5/55 °C). The wear losses of the antagonist tooth and the restorative materials were calculated using reverse modelling software and an electronic scale. VBM and ENA showed significantly higher antagonist tooth wear than PEK (p < 0.05), but there was no significant difference observed among VBM, YAP, MZD, and ENA (p > 0.05). PEK showed the largest value in both material volumetric and weight losses. In terms of material volumetric losses, there was no significant difference between all of the groups (p > 0.05). In terms of material weight losses, PEK was significantly larger than ENA (p < 0.05), but there was no significant difference between VBM, YAP, MZD, and ENA (p > 0.05). Volumetric and weight losses of materials showed similar wear behaviour. However, the wear patterns of antagonists and materials were different, especially in PEK.

Age-associated molecular changes are deleterious and may modulate life span through diet.

Transition through life span is accompanied by numerous molecular changes, such as dysregulated gene expression, altered metabolite levels, and accumulated molecular damage. These changes are thought to be causal factors in aging; however, because they are numerous and are also influenced by genotype, environment, and other factors in addition to age, it is difficult to characterize the cumulative effect of these molecular changes on longevity. We reasoned that age-associated changes, such as molecular damage and tissue composition, may influence life span when used in the diet of organisms that are closely related to those that serve as a dietary source. To test this possibility, we used species-specific culture media and diets that incorporated molecular extracts of young and old organisms and compared the influence of these diets on the life span of yeast, fruitflies, and mice. In each case, the "old" diet or medium shortened the life span for one or both sexes. These findings suggest that age-associated molecular changes, such as cumulative damage and altered dietary composition, are deleterious and causally linked with aging and may affect life span through diet.

Vibrio vulnificus VvhA induces autophagy-related cell death through the lipid raft-dependent c-Src/NOX signaling pathway.

VvhA, a virulent factor of Vibrio (V.) vulnificus, induces acute cell death in a destructive manner. Autophagy plays an important role in cell death, but the functional role of VvhA in autophagy-related cell death has not been elucidated yet. We found that rVvhA significantly increased LC3 puncta formation and autophagic flux in promoting the cell death of human intestinal epithelial Caco-2 cells. The cell death induced by rVvhA was independent of lysosomal permeabilizaton and caspase activation. rVvhA induced rapid phosphorylation of c-Src in the membrane lipid raft, which resulted in an increased interaction between lipid raft molecule caveolin-1 and NADPH oxidase (NOX) complex Rac1 for ROS production. NOX-mediated ROS signaling induced by rVvhA increased the phosphorylation of extracellular signal-regulated kinase (ERK) and eukaryotic translation initiation factor 2α (eIF2α) which are required for mRNA expression of Atg5 and Atg16L1 involved in autophagosome formation. In an in vivo model, VvhA increased autophagy activation and paracellular permeabilization in intestinal epithelium. Collectively, the results here show that VvhA plays a pivotal role in the pathogenesis and dissemination of V. vulnificus by autophagy upregulation, through the lipid raft-mediated c-Src/NOX signaling pathway and ERK/eIF2α activation.

Netrin-1-Induced Stem Cell Bioactivity Contributes to the Regeneration of Injured Tissues via the Lipid Raft-Dependent Integrin α6ß4 Signaling Pathway.

Netrin-1 (Ntn-1) is a multifunctional neuronal signaling molecule; however, its physiological significance, which improves the tissue-regeneration capacity of stem cells, has not been characterized. In the present study, we investigate the mechanism by which Ntn-1 promotes the proliferation of hUCB-MSCs with regard to the regeneration of injured tissues. We found that Ntn-1 induces the proliferation of hUCB-MSCs mainly via Inα6ß4 coupled with c-Src. Ntn-1 induced the recruitment of NADPH oxidases and Rac1 into membrane lipid rafts to facilitate ROS production. The Inα6ß4 signaling of Ntn-1 through ROS production is uniquely mediated by the activation of SP1 for cell cycle progression and the transcriptional occupancy of SP1 on the VEGF promoter. Moreover, Ntn-1 has the ability to induce the F-actin reorganization of hUCB-MSCs via the Inα6ß4 signaling pathway. In an in vivo model, transplantation of hUCB-MSCs pre-treated with Ntn-1 enhanced the skin wound healing process, where relatively more angiogenesis was detected. The potential effect of Ntn-1 on angiogenesis is further verified by the mouse hindlimb ischemia model, where the pre-activation of hUCB-MSCs with Ntn-1 significantly improved vascular regeneration. These results demonstrate that Ntn-1 plays an important role in the tissue regeneration process of hUCB-MSC via the lipid raft-mediated Inα6ß4 signaling pathway.

Regulation of Stem Cell Fate by ROS-mediated Alteration of Metabolism.

Stem cells have attracted much attention due to their distinct features that support infinite self-renewal and differentiation into the cellular derivatives of three lineages. Recent studies have suggested that many stem cells both embryonic and adult stem cells reside in a specialized niche defined by hypoxic condition. In this respect, distinguishing functional differences arising from the oxygen concentration is important in understanding the nature of stem cells and in controlling stem cell fate for therapeutic purposes. ROS act as cellular signaling molecules involved in the propagation of signaling and the translation of environmental cues into cellular responses to maintain cellular homeostasis, which is mediated by the coordination of various cellular processes, and to adapt cellular activity to available bioenergetic sources. Thus, in this review, we describe the physiological role of ROS in stem cell fate and its effect on the metabolic regulation of stem cells.