Erythropoietin prevents hypoxia-induced GATA-4 ubiquitination via phosphorylation of serine 105 of GATA-4

Protection of insect neurons by erythropoietin/CRLF3-mediated regulation of pro-apoptotic acetylcholinesterase

Cytokine receptor-like factor 3 (CRLF3) is a conserved but largely uncharacterized orphan cytokine receptor of eumetazoan animals. CRLF3-mediated neuroprotection in insects can be stimulated with human erythropoietin. To identify mechanisms of CRLF3-mediated neuroprotection we studied the expression and proapoptotic function of acetylcholinesterase in insect neurons. We exposed primary brain neurons from Tribolium castaneum to apoptogenic stimuli and dsRNA to interfere with acetylcholinesterase gene expression and compared survival and acetylcholinesterase expression in the presence or absence of the CRLF3 ligand erythropoietin. Hypoxia increased apoptotic cell death and expression of both acetylcholinesterase-coding genes ace-1 and ace-2. Both ace genes give rise to single transcripts in normal and apoptogenic conditions. Pharmacological inhibition of acetylcholinesterases and RNAi-mediated knockdown of either ace-1 or ace-2 expression prevented hypoxia-induced apoptosis. Activation of CRLF3 with protective concentrations of erythropoietin prevented the increased expression of acetylcholinesterase with larger impact on ace-1 than on ace-2. In contrast, high concentrations of erythropoietin that cause neuronal death induced ace-1 expression and hence promoted apoptosis. Our study confirms the general proapoptotic function of AChE, assigns a role of both ace-1 and ace-2 in the regulation of apoptotic death and identifies the erythropoietin/CRLF3-mediated prevention of enhanced acetylcholinesterase expression under apoptogenic conditions as neuroprotective mechanism.

Targeting GATA4 for cardiac repair

Various strategies have been applied to replace the loss of cardiomyocytes in order to restore reduced cardiac function and prevent the progression of heart disease. Intensive research efforts in the field of cellular reprogramming and cell transplantation may eventually lead to efficient in vivo applications for the treatment of cardiac injuries, representing a novel treatment strategy for regenerative medicine. Modulation of cardiac transcription factor (TF) networks by chemical entities represents another viable option for therapeutic interventions. Comprehensive screening projects have revealed a number of molecular entities acting on molecular pathways highly critical for cellular lineage commitment and differentiation, including compounds targeting Wnt- and transforming growth factor beta (TGFβ)-signaling. Furthermore, previous studies have demonstrated that GATA4 and NKX2-5 are essential TFs in gene regulation of cardiac development and hypertrophy. For example, both of these TFs are required to fully activate mechanical stretch-responsive genes such as atrial natriuretic peptide and brain natriuretic peptide (BNP). We have previously reported that the compound 3i-1000 efficiently inhibited the synergy of the GATA4-NKX2-5 interaction. Cellular effects of 3i-1000 have been further characterized in a number of confirmatory in vitro bioassays, including rat cardiac myocytes and animal models of ischemic injury and angiotensin II-induced pressure overload, suggesting the potential for small molecule-induced cardioprotection.

Ovarian Carcinoma-Associated Mesenchymal Stem Cells Arise from Tissue-Specific Normal Stroma

Carcinoma-associated mesenchymal stem cells (CA-MSCs) are critical stromal progenitor cells within the tumor microenvironment (TME). We previously demonstrated that CA-MSCs differentially express bone morphogenetic protein family members, promote tumor cell growth, increase cancer "stemness," and chemotherapy resistance. Here, we use RNA sequencing of normal omental MSCs and ovarian CA-MSCs to demonstrate global changes in CA-MSC gene expression. Using these expression profiles, we create a unique predictive algorithm to classify CA-MSCs. Our classifier accurately distinguishes normal omental, ovary, and bone marrow MSCs from ovarian cancer CA-MSCs. Suggesting broad applicability, the model correctly classifies pancreatic and endometrial cancer CA-MSCs and distinguishes cancer associated fibroblasts from CA-MSCs. Using this classifier, we definitively demonstrate ovarian CA-MSCs arise from tumor mediated reprograming of local tissue MSCs. Although cancer cells alone cannot induce a CA-MSC phenotype, the in vivo ovarian TME can reprogram omental or ovary MSCs to protumorigenic CA-MSCs (classifier score of >0.96). In vitro studies suggest that both tumor secreted factors and hypoxia are critical to induce the CA-MSC phenotype. Interestingly, although the breast cancer TME can reprogram bone marrow MSCs into CA-MSCs, the ovarian TME cannot, demonstrating for the first time that tumor mediated CA-MSC conversion is tissue and cancer type dependent. Together these findings (a) provide a critical tool to define CA-MSCs and (b) highlight cancer cell influence on distinct normal tissues providing powerful insights into the mechanisms underlying cancer specific metastatic niche formation. Stem Cells 2019;37:257-269.

Downregulation of miR-200c protects cardiomyocytes from hypoxia-induced apoptosis by targeting GATA-4

Hypoxia-induced cardiomyocyte apoptosis plays an important role in the development of ischemic heart disease. MicroRNAs (miRNAs or miRs) are emerging as critical regulators of hypoxia-induced cardiomyocyte apoptosis. miR-200c is an miRNA that has been reported to be related to apoptosis in various pathological processes; however, its role in hypoxia‑induced cardiomyocyte apoptosis remains unclear. In the present study, we aimed to investigate the potential role and underlying mechanism of miR-200c in regulating hypoxia‑induced cardiomyocyte apoptosis. We found that miR-200c was significantly upregulated by hypoxia in cardiomyocytes, as detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The lactate dehydrogenase, MTT, Annexin V/propidium iodide apoptosis and caspase-3 activity assays showed that downregulation of miR-200c markedly improved cell survival and suppressed the apoptosis of cardiomyocytes in response to hypoxia. Bioinformatics analysis and the dual-luciferase reporter assay demonstrated that miR-200c directly targeted the 3'-untranslated region of GATA-4, an important transcription factor for cardiomyocyte survival. RT-qPCR and western blot analysis showed that suppression of miR-200c significantly increased GATA-4 expression. Furthermore, downregulation of miR-200c upregulated the expression of the anti-apoptotic gene Bcl-2. However, the protective effects against hypoxia induced by the downregulation of miR‑200c were significantly abolished by GATA-4 knockdown. Taken together, our results suggest that downregulation of miR-200c protects cardiomyocytes from hypoxia-induced apoptosis by targeting GATA-4, providing a potential therapeutic molecular target for the treatment of ischemic heart disease.

Transcriptomic responses of marine medaka's ovary to hypoxia

Hypoxia, an endocrine disruptor, is pressing global problem affecting marine organisms in over 400 "Dead Zones" worldwide. There is growing evident demonstrated the disruptive effect of hypoxia on reproductive systems of marine fish through the impairments of steroidogenic gene expression, leading to the alteration of sex hormone production in gonads. But the detailed molecular mechanism underlying the responses of female reproductive systems to hypoxic stress remains largely unknown. In the present report, we used marine medaka Oryzias melastigma as a model, together with high-throughput transcriptome sequencing and bioinformatics analysis, aiming to determine the changes in transcriptional signature in the ovary of marine fish under hypoxic stress. Our result discovered over two hundred differential expressed genes in ovary in response to hypoxia. The bioinformatics analysis together with quantitative RT-PCR validation on the deregulated genes highlighted the dysregulations of a number of female reproductive functions including interruptions of ovarian follicle development, gonad development and steroid metabolic process. Additionally, we revealed that these deregulations are through the modulation of leukemia inhibitory factor (LIF), insulin-like growth factor 1 receptor (IGF1R) and follicle stimulating hormone (FSH). The result of this work complements previous studies and provides additional insights into the underlying molecular mechanism of hypoxia-induced impairment of female reproductive system.

Erythropoietin protects myocardium against ischemia-reperfusion injury under moderate hyperglycemia

Erythropoietin (EPO), an essential hormone for erythropoiesis, provides protection against myocardial ischemia/reperfusion (I/R) injury. Hyperglycemia during acute myocardial infarction aggravates organ damage and attenuates the efficacies of various protective measures. This study aimed to investigate the protective role of EPO against myocardial I/R injury under a clinically relevant moderate hyperglycemic condition and its associated mechanisms. Eighty-two Sprague-Dawley rats were randomly assigned to six groups: normoglycemia-Sham, normoglycemia-I/R-control-saline (IRC), normoglycemia-I/R-EPO (IRE), hyperglycemia-Sham, hyperglycemia-IRC, and hyperglycemia-IRE. The rats received 1.2 g/kg dextrose or same volume of normal saline depending on the group. I/R was induced by a 30 min period of ischemia followed by reperfusion for 4 h. For 1 h before I/R injury, intravenous 4000 IU/kg of EPO was administered. EPO pretreatment significantly reduced the number of apoptotic cells and the infarct size compared with those of the control groups. EPO increased GATA-4 phosphorylation and acetylation against I/R in hyperglycemic myocardium. It also enhanced ERK induced GATA-4 post-translational modifications such as increased GATA-4 phosphorylation and acetylation, and decreased GATA-4 ubiquitination following hypoxia-reoxygenation in H9c2 cells in hyperglycemic medium. Increased GATA-4 stability by EPO diminished I/R-related down-regulation of Bcl-2 and reduction of caspase-3 activities in hyperglycemic myocardium. In conclusion, EPO pretreatment before I/R injury conveyed significant myocardial protection under moderate hyperglycemic condition through mechanisms involved in reduction of caspase-3 activity and up-regulation of Bcl-2 in association with enhanced ERK-induced GATA-4 stability.