Estrogen counteracts age-related decline in beige adipogenesis through the NAMPT-regulated ER stress response.

Thermogenic beige adipocytes are recognized as potential therapeutic targets for combating metabolic diseases. However, the metabolic advantages that they offer are compromised with aging. Here we show that treating mice with estrogen (E2), a hormone that decreases with age, can counteract the age-related decline in beige adipogenesis when exposed to cold temperature while concurrently enhancing energy expenditure and improving glucose tolerance in mice. Mechanistically, we found that nicotinamide phosphoribosyl transferase (NAMPT) plays a pivotal role in facilitating the formation of E2-induced beige adipocytes, which subsequently suppresses the onset of age-related endoplasmic reticulum (ER) stress. Furthermore, we found that targeting NAMPT signaling, either genetically or pharmacologically, can restore the formation of beige adipocytes by increasing the number of perivascular adipocyte progenitor cells. Conversely, the absence of NAMPT signaling prevents this process. Together, our findings shed light on the mechanisms regulating the age-dependent impairment of beige adipocyte formation and underscore the E2-NAMPT-controlled ER stress pathway as a key regulator of this process.

Integrated Stress Response Potentiates Ponatinib-Induced Cardiotoxicity.

BACKGROUND: Mitochondrial dysfunction is a primary driver of cardiac contractile failure; yet, the cross talk between mitochondrial energetics and signaling regulation remains obscure. Ponatinib, a tyrosine kinase inhibitor used to treat chronic myeloid leukemia, is among the most cardiotoxic tyrosine kinase inhibitors and causes mitochondrial dysfunction. Whether ponatinib-induced mitochondrial dysfunction triggers the integrated stress response (ISR) to induce ponatinib-induced cardiotoxicity remains to be determined. METHODS: Using human induced pluripotent stem cells-derived cardiomyocytes and a recently developed mouse model of ponatinib-induced cardiotoxicity, we performed proteomic analysis, molecular and biochemical assays to investigate the relationship between ponatinib-induced mitochondrial stress and ISR and their role in promoting ponatinib-induced cardiotoxicity. RESULTS: Proteomic analysis revealed that ponatinib activated the ISR in cardiac cells. We identified GCN2 (general control nonderepressible 2) as the eIF2α (eukaryotic translation initiation factor 2α) kinase responsible for relaying mitochondrial stress signals to trigger the primary ISR effector-ATF4 (activating transcription factor 4), upon ponatinib exposure. Mechanistically, ponatinib treatment exerted inhibitory effects on ATP synthase activity and reduced its expression levels resulting in ATP deficits. Perturbed mitochondrial function resulting in ATP deficits then acts as a trigger of GCN2-mediated ISR activation, effects that were negated by nicotinamide mononucleotide, an NAD+ precursor, supplementation. Genetic inhibition of ATP synthase also activated GCN2. Interestingly, we showed that the decreased abundance of ATP also facilitated direct binding of ponatinib to GCN2, unexpectedly causing its activation most likely because of a conformational change in its structure. Importantly, administering an ISR inhibitor protected human induced pluripotent stem cell-derived cardiomyocytes against ponatinib. Ponatinib-treated mice also exhibited reduced cardiac function, effects that were attenuated upon systemic ISRIB administration. Importantly, ISRIB does not affect the antitumor effects of ponatinib in vitro. CONCLUSIONS: Neutralizing ISR hyperactivation could prevent or reverse ponatinib-induced cardiotoxicity. The findings that compromised ATP production potentiates GCN2-mediated ISR activation have broad implications across various cardiac diseases. Our results also highlight an unanticipated role of ponatinib in causing direct activation of a kinase target despite its role as an ATP-competitive kinase inhibitor.

Nuclear translocation of mitochondrial dehydrogenases as an adaptive cardioprotective mechanism.

Chemotherapy-induced cardiac damage remains a leading cause of death amongst cancer survivors. Anthracycline-induced cardiotoxicity is mediated by severe mitochondrial injury, but little is known about the mechanisms by which cardiomyocytes adaptively respond to the injury. We observed the translocation of selected mitochondrial tricarboxylic acid (TCA) cycle dehydrogenases to the nucleus as an adaptive stress response to anthracycline-cardiotoxicity in human induced pluripotent stem cell-derived cardiomyocytes and in vivo. The expression of nuclear-targeted mitochondrial dehydrogenases shifts the nuclear metabolic milieu to maintain their function both in vitro and in vivo. This protective effect is mediated by two parallel pathways: metabolite-induced chromatin accessibility and AMP-kinase (AMPK) signaling. The extent of chemotherapy-induced cardiac damage thus reflects a balance between mitochondrial injury and the protective response initiated by the nuclear pool of mitochondrial dehydrogenases. Our study identifies nuclear translocation of mitochondrial dehydrogenases as an endogenous adaptive mechanism that can be leveraged to attenuate cardiomyocyte injury.

Modulation of lncRNA links endothelial glycocalyx to vascular dysfunction of tyrosine kinase inhibitor.

AIMS: Novel cancer therapies leading to increased survivorship of cancer patients have been negated by a concomitant rise in cancer therapies-related cardiovascular toxicities. Sunitinib, a first line multi-receptor tyrosine kinase inhibitor, has been reported to cause vascular dysfunction although the initiating mechanisms contributing to this side effect remain unknown. Long non-coding RNAs (lncRNAs) are emerging regulators of biological processes in endothelial cells (ECs); however, their roles in cancer therapies-related vascular toxicities remain underexplored. METHODS AND RESULTS: We performed lncRNA expression profiling to identify potential lncRNAs that are dysregulated in human-induced pluripotent stem cell-derived ECs (iPSC-ECs) treated with sunitinib. We show that the lncRNA hyaluronan synthase 2 antisense 1 (HAS2-AS1) is significantly diminished in sunitinib-treated iPSC-ECs. Sunitinib was found to down-regulate HAS2-AS1 by an epigenetic mechanism involving hypermethylation. Depletion of HAS2-AS1 recapitulated sunitinib-induced detrimental effects on iPSC-ECs, whereas CRISPR-mediated activation of HAS2-AS1 reversed sunitinib-induced dysfunction. We confirmed that HAS2-AS1 stabilizes the expression of its sense gene HAS2 via an RNA/mRNA heteroduplex formation. Knockdown of HAS2-AS1 led to reduced synthesis of hyaluronic acid (HA) and up-regulation of ADAMTS5, an enzyme involved in extracellular matrix degradation, resulting in disruption of the endothelial glycocalyx which is critical for ECs. In vivo, sunitinib-treated mice showed reduced coronary flow reserve, accompanied by a reduction in Has2os and degradation of the endothelial glycocalyx. Finally, we identified that treatment with high molecular-weight HA can prevent the deleterious effects of sunitinib both in vitro and in vivo by preserving the endothelial glycocalyx. CONCLUSIONS: Our findings highlight the importance of lncRNA-mediated regulation of the endothelial glycocalyx as an important determinant of sunitinib-induced vascular toxicity and reveal potential novel therapeutic avenues to attenuate sunitinib-induced vascular dysfunction.

METTL14 Regulates Osteogenesis of Bone Marrow Mesenchymal Stem Cells via Inducing Autophagy Through m6A/IGF2BPs/Beclin-1 Signal Axis.

The development of osteoporosis is often accompanied by autophagy disturbance, which also causes new osteoblast defects from bone marrow mesenchymal stem cells (BMSCs). However, the underlying molecular mechanisms are still not fully understood. Methyltransferase-like 14 (METTL14) is the main enzyme for N6-methyladenosine (m6A), the most prevalent internal modification in mammalian mRNAs, and it has been implicated in many bioprocesses. Herein, we demonstrate that METTL14 plays a critical role in autophagy induction and hinders osteoporosis process whose expression is decreased both in human osteoporosis bone tissue and ovariectomy (OVX) mice. In vivo, METTL14+/- knockdown mice exhibit elevated bone loss and impaired autophagy similar to the OVX mice, while overexpression of METTL14 significantly promotes bone formation and inhibits the progression of osteoporosis caused by OVX surgery. In vitro, METTL14 overexpression significantly enhances the osteogenic differentiation ability of BMSCs through regulating the expression of beclin-1 depending on m6A modification and inducing autophagy; the opposite is true with METTL14 silencing. Subsequently, m6A-binding proteins IGF2BP1/2/3 recognize m6A-methylated beclin-1 mRNA and promote its translation via mediating RNA stabilization. Furthermore, METTL14 negatively regulates osteoclast differentiation. Collectively, our study reveals the METTL14/IGF2BPs/beclin-1 signal axis in BMSCs osteogenic differentiation and highlights the critical roles of METTL14-mediated m6A modification in osteoporosis.

METTL3 induces bone marrow mesenchymal stem cells osteogenic differentiation and migration through facilitating M1 macrophage differentiation.

Despite the crucial role of m6A methyltransferase METTL3 in multiple diseases onset and progression, there are still lacking hard evidence proving that METTL3 could affect macrophage polarization in the stage of bone repair. Here, we aimed to explore the potential involvement of METTL3 in bone repair through modulating macrophage polarization and decipher the underlying cellular/molecular mechanisms. Here we treated RAW 264.7 cells and BM-derived primary macrophages (BMDM) with lipopolysaccharide (LPS) to induce M1 differentiation. METTL3 expression was upregulated in pro-inflammatory macrophages (M1) as compared with macrophages (M0). And overexpression of METTL3 promoted the expression of IL-6 and iNOS secretion by M1 macrophage. In the coculture condition, M1 macrophages with forced expression of METTL3 significantly enhanced migration ability of BMSCs, and also remarkably facilitated osteogenesis ability of BMSCs; the opposite was true when expression of METTL3 was knockdown. In addition, the m6A-RIP microarray suggested that METTL3 silencing significantly reduce the m6A modification of DUSP14, HDAC5 and Nfam1. Furthermore, the findings showed that expression of HADC5 was downregulated in M1 macrophages with METTL3 knockdown, while the DUSP14 expression had slight change and Nfam1 expression was very low. In contrast, METTL3 overexpression promoted HDAC5 expression, indicating that HDAC5 is the critical target gene of METTL3. Under such a theme, we proposed that METTL3 overexpression might be a new approach of replacement therapy for the treatment of bone repair.

Blue LED causes autophagic cell death in human osteosarcoma by increasing ROS generation and dephosphorylating EGFR.

Osteosarcoma (OS) is the most common primary malignant bone tumour in adolescence. Lately, light-emitting diodes (LED)-based therapy has emerged as a new promising approach for several diseases. However, it remains unknown in human OS. Here, we found that the blue LED irradiation significantly suppressed the proliferation, migration and invasion of human OS cells, while we observed blue LED irradiation increased ROS production through increased NADPH oxidase enzymes NOX2 and NOX4, as well as decreased Catalase (CAT) expression levels. Furthermore, we revealed blue LED irradiation-induced autophagy characterized by alterations in autophagy protein markers including Beclin-1, LC3-II/LC3-I and P62. Moreover, we demonstrated an enhanced autophagic flux. The blockage of autophagy displayed a remarkable attenuation of anti-tumour activities of blue LED irradiation. Next, ROS scavenger N-acetyl-L-cysteine (NAC) and NOX inhibitor diphenyleneiodonium (DPI) blocked suppression of OS cell growth, indicating that ROS accumulation might play an essential role in blue LED-induced autophagic OS cell death. Additionally, we observed blue LED irradiation decreased EGFR activation (phosphorylation), which in turn led to Beclin-1 release and subsequent autophagy activation in OS cells. Analysis of EGFR colocalization with Beclin-1 and EGFR-immunoprecipitation (IP) assay further revealed the decreased interaction of EGFR and Beclin-1 upon blue LED irradiation in OS cells. In addition, Beclin-1 down-regulation abolished the effects of blue LED irradiation on OS cells. Collectively, we concluded that blue LED irradiation exhibited anti-tumour effects on OS by triggering ROS and EGFR/Beclin-1-mediated autophagy signalling pathway, representing a potential approach for human OS treatment.

ALKBH5 suppresses tumor progression via an m6A-dependent epigenetic silencing of pre-miR-181b-1/YAP signaling axis in osteosarcoma.

ALKBH5 is the main enzyme for m6A-based demethylation of RNAs and it has been implicated in many biological and pathophysiological processes. Here, we aimed to explore the potential involvement of ALKBH5 in osteosarcoma and decipher the underlying cellular/molecular mechanisms. We discovered downregulated levels of demethylase ALKBH5 were correlated with increased m6A methylation in osteosarcoma cells/tissues compared with normal osteoblasts cells/tissues. ALKBH5 overexpression significantly suppressed osteosarcoma cell growth, migration, invasion, and trigged cell apoptosis. In contrast, inhibition of ALKBH5 produced the opposite effects. Whereas ALKBH5 silence enhanced m6A methylations of pre-miR-181b-1 and YAP-mRNA exerting oncogenic functions in osteosarcoma. Moreover, upregulation of YAP or downregulation of mature miR-181b-5p displayed a remarkable attenuation of anti-tumor activities caused by ALKBH5. Further results revealed that m6A methylated pre-miR-181b-1 was subsequently recognized by m6A-binding protein YTHDF2 to mediate RNA degradation. However, methylated YAP transcripts were recognized by YTHDF1 to promote its translation. Therefore, ALKBH5-based m6A demethylation suppressed osteosarcoma cancer progression through m6A-based direct/indirect regulation of YAP. Thus, ALKBH5 overexpression might be considered a new approach of replacement therapy for osteosarcoma treatment.

Inhibition of cardiomyocyte differentiation of human induced pluripotent stem cells by Ribavirin: Implication for its cardiac developmental toxicity.

Ribavirin has been proven to be an antiviral treatment, whereas there are still risks of hemolysis and congenital malformation. Abnormal cardiac development contributes to the occurrence and development of many heart diseases. However, there is so far no evidence that ribavirin induces human cardiac developmental toxicity. Herein, we employed the cardiac differentiation model of human induced pluripotent stem cells (hiPSCs) to determine the impact of ribavirin on heart development. Our data showed that ribavirin at clinically high concentrations (5 and 10 µM) significantly inhibited the proliferation and differentiation of hiPSCs from mesoderm to cardiac progenitor cells and cardiac progenitor cells to cardiomyocytes, but not from pluripotent status to mesoderm. Meanwhile, DCFH-DA staining revealed that ribavirin could increase ROS content in the mid-phase of differentiation. In addition, ribavirin treatment (1, 5 and 10 µM) remarkably caused DNA damage which was shown by the increase of γH2AX-positive cells and upregulation of the p53 during the differentiation of hiPSCs from mesoderm to cardiac progenitor cells. Moreover, exposuring to ribavirin (5 and 10 µM) markedly upregulated the expression of lncRNAs Gas5 in both mid-phase and late phase of differentiation and HBL1 in the mid-phase. In conclusion, our results suggest that ribavirin is detrimental in cardiac differentiation of hiPSCs, which may be associated with DNA damage, upregulated p53 and increased Gas5. It may provide the evidence for the rational clinical application of ribavirin.

Iron overload inhibits self-renewal of human pluripotent stem cells via DNA damage and generation of reactive oxygen species.

Iron overload affects the cell cycle of various cell types, but the effect of iron overload on human pluripotent stem cells has not yet been reported. Here, we show that the proliferation capacities of human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) were significantly inhibited by ferric ammonium citrate (FAC) in a concentration-dependent manner. In addition, deferoxamine protected hESCs/hiPSCs against FAC-induced cell-cycle arrest. However, iron overload did not affect pluripotency in hESCs/hiPSCs. Further, treatment of hiPSCs with FAC resulted in excess reactive oxygen species production and DNA damage. Collectively, our findings provide new insights into the role of iron homeostasis in the maintenance of self-renewal in human pluripotent stem cells.

m6A Methylation of Precursor-miR-320/RUNX2 Controls Osteogenic Potential of Bone Marrow-Derived Mesenchymal Stem Cells.

Methyltransferase-like 3 (METTL3) is the main enzyme for N6-methyladenosine (m6A)-based methylation of RNAs and it has been implicated in many biological and pathophysiological processes. In this study, we aimed to explore the potential involvement of METTL3 in osteoblast differentiation and decipher the underlying cellular and molecular mechanisms. We demonstrated that METTL3 is downregulated in human osteoporosis and the ovariectomized (OVX) mouse model, as well as during the osteogenic differentiation. Silence of METTL3 by short interfering RNA (siRNA) decreased m6A methylation levels and inhibited osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and reduced bone mass, and similar effects were observed in METTL3+/- knockout mice. In contrast, adenovirus-mediated overexpression of METTL3 produced the opposite effects. In addition, METTL3 enhanced, whereas METTL3 silence or knockout suppressed, the m6A methylations of runt-related transcription factor 2 (RUNX2; a key transcription factor for osteoblast differentiation and bone formation) and precursor (pre-)miR-320. Moreover, downregulation of mature miR-320 rescued the decreased bone mass caused by METTL3 silence or METTL3+/- knockout. Therefore, METTL3-based m6A modification favors osteogenic differentiation of BMSCs through m6A-based direct and indirect regulation of RUNX2, and abnormal downregulation of METTL3 is likely one of the mechanisms underlying osteoporosis in patients and mice. Thus, METTL3 overexpression might be considered a new approach of replacement therapy for the treatment of human osteoporosis.

Melatonin triggers autophagic cell death by regulating RORC in Hodgkin lymphoma.

Melatonin (Mel) has been shown to involve in many essential cell functions via modulating many signaling pathways. We for the first time investigated that Mel exerted anti-tumor activities in Hodgkin lymphoma (HL) via inhibiting cell proliferation and promoting cell apoptosis. Further study revealed that Mel treatment increased expression of LC3-II and decreased p62 proteins with the enhanced production of autolysosome, indicating it induced activation of autophagy. Nevertheless, Mel treatment together with autophagy inhibitors 3-MA or CQ exacerbated the damage effect of Mel in HL cells, which means autophagy plays a protective role in this process. Furthermore, we found Mel treatment increased the expression of G protein-coupled receptors MT2 and retinoic acid-related orphan receptors (RORs), eg. RORA, RORB and RORC. While RORC has the highest increase in Mel treated HL cells. In addition, RORC overexpression induced autophagy activation. Therefore, Mel showed tumor-suppressive role due to an increased level of RORC induced autophagy in HL.

MicroRNA-92b-5p modulates melatonin-mediated osteogenic differentiation of bone marrow mesenchymal stem cells by targeting ICAM-1.

Osteoporosis is closely associated with the dysfunction of bone metabolism, which is caused by the imbalance between new bone formation and bone resorption. Osteogenic differentiation plays a vital role in maintaining the balance of bone microenvironment. The present study investigated whether melatonin participated in the osteogenic commitment of bone marrow mesenchymal stem cells (BMSCs) and further explored its underlying mechanisms. Our data showed that melatonin exhibited the capacity of regulating osteogenic differentiation of BMSCs, which was blocked by its membrane receptor inhibitor luzindole. Further study demonstrated that the expression of miR-92b-5p was up-regulated in BMSCs after administration of melatonin, and transfection of miR-92b-5p accelerated osteogenesis of BMSCs. In contrast, silence of miR-92b-5p inhibited the osteogenesis of BMSCs. The increase in osteoblast differentiation of BMSCs caused by melatonin was attenuated by miR-92b-5p AMO as well. Luciferase reporter assay, real-time qPCR analysis and western blot analysis confirmed that miR-92b-5p was involved in osteogenesis by directly targeting intracellular adhesion molecule-1 (ICAM-1). Melatonin improved the expression of miR-92b-5p, which could regulate the differentiation of BMSCs into osteoblasts by targeting ICAM-1. This study provided novel methods for treating osteoporosis.

Arsenic trioxide blocked proliferation and cardiomyocyte differentiation of human induced pluripotent stem cells: Implication in cardiac developmental toxicity.

Arsenic trioxide (ATO) has been recommended as the first-line agent for the treatment of acute promyelocytic leukaemia (APL), due to its substantial anticancer effect. Numerous clinical reports have indicated that ATO is a developmental toxicant which can result in birth defects of human beings. But whether arsenic trioxide can lead to human cardiac developmental toxicity remains largely unknown. So the present study aims to explore the influence and mechanisms of ATO on human cardiac development by using a vitro cardiac differentiation model of human induced pluripotent stem cells (hiPSCs). Here we found that clinically achievable concentrations (0.1, 0.5 and 1 µM) of ATO resulted in a significant inhibition of proliferation during the whole process of cardiac differentiation of hiPSCs. Meanwhile, TUNEL assay revealed that ATO could cause cell apoptosis during cardiac differentiation in a concentration-dependent manner. Consistently, we found that ATO reduced the expressions of mesoderm markers Brachyury and EOMES, cardiac progenitor cell markers GATA-4, MESP-1 and TBX-5, and cardiac specific marker α-actinin in differentiated hiPSCs. Furthermore, ATO treatment had caused DNA damage which was shown in the upregulation of γH2AX, a sensitive marker for DNA double-strand breaks. Taken together, ATO blocked cardiomyocyte differentiation, induced apoptosis and cell growth arrest during cardiac differentiation of hiPSCs, which might be associated with DNA damage.

Synergistic anti-tumor effects of arsenic trioxide and blue LED irradiation on human osteosarcoma.

Arsenic trioxide (ATO) has been well recognized as an anti-tumor agent for various human cancers. Recently, the blue light emitting diodes (LEDs)-based therapy has also been demonstrated to be potential therapeutic strategies for several cancers. However, the combination effects of ATO and blue LED on tumor suppression are still unclear. In this study, we determined whether combination of ATO and blue LED irradiation at 470 nm in wavelength exhibited superior anti-tumor activity in human osteosarcoma (OS). We observed that combination treatments of ATO and blue LED much more significantly decreased the percentages of proliferative cells, and increased apoptotic rate compared with any single treatments in U-2 OS cells. Furthermore, we found suppression of cell migration and invasion were much more pronounced in ATO plus blue LED treated group than single treated groups. Moreover, reactive oxygen species (ROS) assay and immunostaining of γ-H2A.X and p53 indicated that the combined treatments resulted in further markedly increases in ROS accumulation, DNA damage and p53 activity. Taken together, our study demonstrated synergistical anti-tumor effects of combined treatments of ATO and blue LED on human OS cells, which were associated with an increased ROS accumulation, DNA damaged mediated p53 activation.

The Long Non-coding RNA-ORLNC1 Regulates Bone Mass by Directing Mesenchymal Stem Cell Fate.

Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to differentiate into osteoblasts or adipocytes, and the shift between osteogenic and adipogenic differentiation determines bone mass. The aim of this study was to identify whether lncRNAs are involved in the differentiation commitment of BMSCs during osteoporosis. Here, we found ORLNC1, a functionally undefined lncRNA that is highly conserved, which exhibited markedly higher expression levels in BMSCs, bone tissue, and the serum of OVX-induced osteoporotic mice than sham-operated counterparts. Notably, a similar higher abundance of lncRNA-ORLNC1 expression was also observed in the bone tissue of osteoporotic patients. The transgenic mice overexpressing lncRNA-ORLNC1 showed a substantial increase in the osteoporosis-associated bone loss and decline in the osteogenesis of BMSCs. The BMSCs pretreated with lncRNA-ORLNC1-overexpressing lentivirus vector exhibited the suppressed capacity of osteogenic differentiation and oppositely enhanced adipogenic differentiation. We then established that lncRNA-ORLNC1 acted as a competitive endogenous RNA (ceRNA) for miR-296. Moreover, miR-296 was found markedly upregulated during osteoblast differentiation, and it accelerated osteogenic differentiation by targeting Pten. Taken together, our results indicated that the lncRNA-ORLNC1-miR-296-Pten axis may be a critical regulator of the osteoporosis-related switch between osteogenesis and adipogenesis of BMSCs and might represent a plausible therapeutic target for improving osteoporotic bone loss.

Iron Homeostasis Determines Fate of Human Pluripotent Stem Cells Via Glycerophospholipids-Epigenetic Circuit.

Iron homeostasis is crucial for a variety of biological processes, but the biological role of iron homeostasis in pluripotent stem cells (PSCs) remains largely unknown. The present study aimed to determine whether iron homeostasis is involved in maintaining the pluripotency of human PSCs (hPSCs). We found that the intracellular depletion of iron leads to a rapid downregulation of NANOG and a dramatic decrease in the self-renewal of hPSCs as well as spontaneous and nonspecific differentiation. Moreover, long-term depletion of iron can result in the remarkable cell death of hPSCs via apoptosis and necrosis pathways. Additionally, we found that the depletion of iron increased the activity of lipoprotein-associated phospholipase A2 (LP-PLA2) and the production of lysophosphatidylcholine, thereby suppressing NANOG expression by enhancer of zeste homolog 2-mediated trimethylation of histone H3 lysine 27. Consistently, LP-PLA2 inhibition abrogated iron depletion-induced loss of pluripotency and differentiation. Altogether, the findings of our study demonstrates that iron homeostasis, acting through glycerophospholipid metabolic pathway, is essential for the pluripotency and survival of hPSCs. Stem Cells 2019;37:489-503.

Blue light emitting diodes irradiation causes cell death in colorectal cancer by inducing ROS production and DNA damage.

The light emitting diodes (LEDs) irradiation has been demonstrated to be potential therapeutic strategies for several diseases. However, the blue LED effects remain largely unknown in colorectal cancer (CRC), which is a major cause of morbidity and mortality throughout the world. In this study, we determined the effects of blue LED irradiation, the maximal light emission at 470 nm in wavelength, in human CRC cell lines SW620 and HT29. The cells were irradiated with blue LED light for 0 J/cm2, 72 J/cm2, 144 J/cm2, 216 J/cm2 and 288 J/cm2 respectively. We found that irradiation with blue LED light induced a marked decrease of live cells and an increase of dead cells. Additionally, lower cell proliferation and a remarkably increase of cell apoptosis were observed in blue LED-irradiated cells as compared with non-irradiated control group. The cell migration was significantly inhibited by blue LED irradiation 24, 48 and 72 h later compared with non-treated group. Blue LED-treated CRC cells further displayed a remarkably inhibition of EMT process in CRC cells. Finally, we found the accumulation of ROS production and DNA damage were induced by blue LED irradiation. These results indicated that blue LED irradiation inhibits CRC cell proliferation, migration and EMT process as well as induces cell apoptosis, which may result from increased ROS accumulation and induction of DNA damage.

The Long Noncoding RNA CAREL Controls Cardiac Regeneration.

BACKGROUND: Adult mammalian heart loses regeneration ability following ischemic injury due to the loss of cardiomyocyte mitosis. However, the molecular mechanisms underlying the post-mitotic nature of cardiomyocytes remain largely unknown. OBJECTIVES: The purpose of this study was to define the essential role of long noncoding ribonucleic acids (lncRNAs) in heart regeneration during postnatal and adult injury. METHODS: Myh6-driving cardiomyocyte-specific lncRNA-CAREL transgenic mice and adenovirus-mediated in vivo silencing of endogenous CAREL were used in this study. The effect of CAREL on cardiomyocyte replication and heart regeneration after apical resection or myocardial infarction was assessed by detecting mitosis and cytokinesis. RESULTS: An lncRNA CAREL was found significantly up-regulated in cardiomyocytes from neonatal mice (P7) in parallel with loss of regenerative capacity. Cardiac-specific overexpression of CAREL in mice reduced cardiomyocyte division and proliferation and blunted neonatal heart regeneration after injury. Conversely, silencing of CAREL in vivo markedly promoted cardiac regeneration and improved heart functions after myocardial infarction in neonatal and adult mice. CAREL acted as a competing endogenous ribonucleic acid for miR-296 to derepress the expression of Trp53inp1 and Itm2a, the target genes of miR-296. Consistently, overexpression of miR-296 significantly increased cardiomyocyte replication and cardiac regeneration after injury. Decline of cardiac regenerative ability in CAREL transgenic mice was also rescued by miR-296. A short fragment containing the conserved sequence of CAREL reduced the proliferation of human induced pluripotent stem cell-derived cardiomyocytes as the full-length CAREL. CONCLUSIONS: LncRNA CAREL regulates cardiomyocyte proliferation and heart regeneration in postnatal and adult heart after injury by acting as a competing endogenous ribonucleic acid on miR-296 that targets Trp53inp1 and Itm2a.

Effects of Blue Light Emitting Diode Irradiation On the Proliferation, Apoptosis and Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells.

BACKGROUND/AIMS: Blue light emitting diodes (LEDs) have been proven to affect the growth of several types of cells. The effects of blue LEDs have not been tested on bone marrow-derived mesenchymal stem cells (BMSCs), which are important for cell-based therapy in various medical fields. Therefore, the aim of this study was to determine the effects of blue LED on the proliferation, apoptosis and osteogenic differentiation of BMSCs. METHODS: BMSCs were irradiated with a blue LED light at 470 nm for 1 min, 5 min, 10 min, 30 min and 60 min or not irradiated. Cell proliferation was measured by performing cell counting and EdU staining assays. Cell apoptosis was detected by TUNEL staining. Osteogenic differentiation was evaluated by ALP and ARS staining. DCFH-DA staining and γ-H2A.X immunostaining were used to measure intracellular levels of ROS production and DNA damage. RESULTS: Both cell counting and EdU staining assays showed that cell proliferation of BMSCs was significantly reduced upon blue LED irradiation. Furthermore, treatment of BMSCs with LED irradiation was followed by a remarkable increase in apoptosis, indicating that blue LED light induced toxic effects on BMSCs. Likewise, BMSC osteogenic differentiation was inhibited after exposure to blue LED irradiation. Further, blue LED irradiation was followed by the accumulation of ROS production and DNA damage. CONCLUSIONS: Taken together, our study demonstrated that blue LED light inhibited cell proliferation, inhibited osteogenic differentiation, and induced apoptosis in BMSCs, which are associated with increased ROS production and DNA damage. These findings may provide important insights for the application of LEDs in future BMSC-based therapies.