Expression and characterization of the PEBP homolog genes from Drosophila

Evaluation the Therapeutic Effect of Adipose-Derived Mesenchymal Stem Cells on Chronic Mild Stress by Activating PEBP1-GPX4 Axis in Ferroptosis Using qRT-PCR, Fluorescence Microscope and Iron Determination Analysis

About 50% of depressive patients failed to respond to the treatment, mainly because of insufficient knowledge about the pathogenesis of depression. The current study’s objectives were to look into the potential role of ferroptosis in the etiology of depression in the mice model of chronic mild stress (CMS) and investigate the effects of adipose-derived mesenchymal stem cells (ADSCs) on PEBP1-GPX4 axis controlled ferroptosis in mice. We grouped the male C57BL/6 mice randomly as follows: normal control (NC), CMS, and CMS+ADSCs. The second two groups’ animals were exposed to CMS for a total of six weeks. From the fourth week of modeling to the sixth week, cell therapy was given once a week. SPT, TST, FST, and NSFT behavior assessments were used to evaluate the depression-like behavior brought on by CMS. We selected the ferroptosis-related parameters, including the expression of GPX4, FTH1, ACSL4, and COX2. The amount of iron was determined in the hippocampus of the model organism by using the iron assay kit. By measuring the PEBP1 and ERK1/2 levels, as well as evaluating the expression of GFAP and IBA1, we assessed the biological function of astrocytes and microglia in mice hippocampus. It was found that six weeks after modeling in the CMS+ADSCs group, the mice’s depression-like behavior induced by CMS had significantly improved. We found a significantly changed level of genes, including GPX4, ACSL4, FTH1, COX2, ERK1/2, GFAP, PEBP1 and IBA1. Also, we found the differentiated level of total and ferric iron in our model mice. All these findings demonstrated that ADSCs had a therapeutic effect on CMS-induced depression-like behavior, probably by activating the PEBP1-GPX4 axis in ferroptosis. This anti-depression role of ADSCs may be associated with the activation of the PEBP1-GPX4 axis in ferroptosis, implying that regulation of ferroptosis is a crucial therapeutic target for depression.

Traditional Chinese Formula Xiaoyaosan Alleviates Depressive-Like Behavior in CUMS Mice by Regulating PEBP1-GPX4-Mediated Ferroptosis in the Hippocampus

BACKGROUND

At present, the pathogenesis of depression is not fully understood, and nearly half of depression patients experience no obvious effects during treatment. This study aimed to establish a depression mouse model to explore the possible role of ferroptosis in the pathogenesis of depression, and observe the effects of Xiaoyaosan on PEBP1-GPX4-mediated ferroptosis in the hippocampus.

METHODS

Forty-eight male C57BL/6 mice were randomly divided into a control group, CUMS group, Xiaoyaosan group and fluoxetine group, and the model was established by chronic unpredictable mild stress (CUMS) for a successive 6 weeks. The medication procedure was performed from the 4th to the 6th week of modeling. The behavioral evaluations were measured to evaluate depressive-like behaviors. The expressions of GPX4, FTH1, ACSL4 and COX2 were detected as ferroptosis-related indicators. Then, the total iron and ferrous content in the hippocampus were measured. The levels of PEBP1 and ERK1/2 were observed, and the expressions of GFAP and IBA1 were also detected to measure the functions of astrocytes and microglia in the hippocampus.

RESULTS

Eight herbs of Xiaoyaosan had 133 active ingredients which could regulate the 43 ferroptosis-related genes in depression. After 6 weeks of modeling, the data showed that mice in the CUMS group had obvious depressive-like behaviors, and medication with Xiaoyaosan or fluoxetine could significantly improve the behavioral changes. The expressions of GPX4, FTH1, ACSL4, COX2, PEBP1, ERK1/2, GFAP and IBA1 changed in the CUMS group mice, while the total iron and ferrous content also changed. Xiaoyaosan and fluoxetine had obvious curative effects that could significantly alleviate the above changes in the hippocampus.

CONCLUSION

Our results revealed that the activation of ferroptosis might exist in the hippocampi of CUMS-induced mice. The PEBP1-GPX4-mediated ferroptosis could be involved in the antidepressant mechanism of Xiaoyaosan. It also implied that ferroptosis could become a new target for research into the depression mechanism and antidepressant drugs.

Actomyosin contraction during cellularization is regulated in part by Src64 control of Actin 5C protein levels

Src64 is required for actomyosin contraction during cellularization of the Drosophila embryonic blastoderm. The mechanism of actomyosin ring constriction is poorly understood even though a number of cytoskeletal regulators have been implicated in the assembly, organization, and contraction of these microfilament rings. How these cytoskeletal processes are regulated during development is even less well understood. To investigate the role of Src64 as an upstream regulator of actomyosin contraction, we conducted a proteomics screen to identify proteins whose expression levels are controlled by src64. Global levels of actin are reduced in src64 mutant embryos. Furthermore, we show that reduction of the actin isoform Actin 5C causes defects in actomyosin contraction during cellularization similar to those caused by src64 mutation, indicating that a relatively high level of Actin 5C is required for normal actomyosin contraction and furrow canal structure. However, reduction of Actin 5C levels only slows down actomyosin ring constriction rather than preventing it, suggesting that src64 acts not only to modulate actin levels, but also to regulate the actomyosin cytoskeleton by other means.

Knockdown of PEBP4 inhibits human glioma cell growth and invasive potential via ERK1/2 signaling pathway

Phosphatidylethanolamine (PE)-binding protein 4 (PEBP4) is an antiapoptotic protein that is aberrantly expressed in various malignancies. We previously demonstrated that PEBP4 expression is dramatically induced in human gliomas and positively correlated with tumor grade and patient survival. However, the function of PEBP4 in human glioma development and underlying mechanisms remain largely unknown. By stable lentiviral vector-mediated silencing of PEBP4, we examined the effects of PEBP4 knockdown on the growth, apoptosis, and invasion of U251 and U373 human glioma cell lines using MTT, Transwell, colony formation, and flow cytometric assays. We examined the in vivo role of PEBP4 in tumor growth by inoculation of BALB/c nu/nu male mice with PEBP4-deficient U251 and U373 cells. The expression of cell cycle- and apoptosis-related proteins was analyzed by Western blotting and immunostaining. Knockdown of PEBP4 significantly reduced the proliferation and invasion of human glioma cells while inducing cell apoptosis by altering the expression of cell cycle- and apoptosis-related proteins. Mechanistically, PEBP4 knockdown led to activation of the extracellular signal-regulated kinases 1/2 (ERK1/2) pathway, an effect that could be reversed by U0126, a selective inhibitor of MEK1/2 (upstream of ERK1/2), suggesting involvement of ERK1/2 signaling in the regulation of glioma development and progression by PEBP4. We identified PEBP4 as a novel regulator mediating human glioma cell proliferation, invasion, and apoptosis as well as tumor formation and growth. Therefore, PEBP4 may be a potential therapeutic target in human glioma treatment.

Drosophila PEBP1 inhibits intestinal stem cell aging via suppression of ERK pathway

The intestine is a high cellular turnover tissue largely dependent on the regenerative function of stem cell throughout life, and a signaling center for the health and viability of organisms. Therefore, better understanding of the mechanisms underlying the regulation of intestinal stem cell (ISC) regenerative potential is essential for the possible intervention of aging process and age-related diseases. Drosophila midgut is a well-established model system for studying the mechanisms underlying ISC regenerative potential during aging. Here, we report the requirement of Drosophila phosphatidylethanolamine binding protein 1 (PEBP1) in ISC regenerative potential. We showed that PEBP1 was strongly expressed in enterocytes (ECs) of guts and its decrease with age and oxidative stress. Furthermore, the downregulation of PEBP1 in ECs accelerates ISC aging, as evidenced by ISC hyper-proliferation, γH2AX accumulation, and centrosome amplification, and intestinal hyperplasia. The decrease in PEBP1 expression was associated with increased extracellular signal-regulated kinase (ERK) activity in ECs. All these phenotypes by EC-specific depletion of PEBP1 were rescued by the concomitant inhibition of ERK signaling. Our findings evidence that the age-related downregulation of PEBP1 in ECs is a novel cause accelerating ISC aging and that PEBP1 is an EC-intrinsic suppressor of epidermal growth factor receptor (EGFR)/ERK signaling. Our study provides molecular insights into the tight regulation of EGFR/ERK signaling in niches for stem cell regenerative potential.

Transcript expression bias of phosphatidylethanolamine binding protein gene in bumblebee, Bombus lantschouensis (Hymenoptera: Apidae)

The phosphatidylethanolamine-binding protein (PEBP) family is a highly conserved group of proteins found in a wide range of organism. It plays an important role in innate immunity of insects. Little is known on the expression characteristic and function of PEBP in bees. In the current study, we cloned the pebp gene and investigated its expression profiles at different developmental stages and reproductive status from bumblebee, Bombus lantschouensis (Vogt), which is one of the most abundant pollinators for wild plants and crops in Northern China. Two transcripts (PEBPX1 and PEBPX2) of the pebp gene were cloned for the first time. The transcript PEBPX2 lacked a signal peptide sequence compared to PEBPX1. The full-length cDNA of these two PEBP transcripts is 1005bp and 915bp, with an open reading frame of 627bp and 549bp, respectively. Transcript PEBPX2 was one order of magnitude more expressed than transcript PEBPX1 at most of the developmental stages and different reproductive status (egg-laying versus non- egg-laying females). Both of the PEBP transcripts were highly expressed in brown-eyed with light and dark pigmented cuticle pupae stages. Quantitative PCR and Western Blot demonstrated that PEBP was significantly up-regulated in egg-laying females. In summary, we suggest that levels of these two PEBPs could be related to the regulation of reproduction in bumblebees. In addition, both transcripts likely play an important role in the metamorphosis developmental stage of bumblebee pupae.

Increased expression of phosphatidylethanolamine-binding protein 4 (PEBP4) strongly associates with human gliomas grade

Abnormal expression of phosphatidylethanolamine-binding protein 4 (PEBP4) has been found in various types of malignancies. However, the PEBP4 expression in human gliomas is still unclear. In this study, we aim to compare the expression of PEBP4 in tumor samples derived from 58 patients with different grades of gliomas with that in 5 non-neoplastic brain samples and to investigate the clinical significance of PEBP4 expression in gliomas. The mRNA and protein expressions of PEBP4 were measured by real-time quantitative polymerase chain reaction and western blot, respectively. The intracellular expressions of PEBP4 in samples were examined by immunohistochemistry. The association between PEBP4 expression and the clinicopathologic characteristics of gliomas patients were analyzed. Our results demonstrated that the mRNA and protein levels of PEBP4 were upregulated in gliomas tissues, especially in high-grade (World Health Organization Grades III and IV) gliomas, when compared to normal control (p < 0.01). Immunohistochemical analysis indicated that PEBP4 was highly expressed in 82.4% (28/34) of high-grade gliomas, when compared to 41.7% (10/24) of high expression in low-grade gliomas and 20.0% (1/5) in non-neoplastic brain samples (p = 0.001). Multivariate Cox regression analysis revealed that increased PEBP4 expression was an independent prognostic factor for gliomas. Patients with low level of PEBP4 had longer survival time compared to those with high PEBP4 expression (p = 0.003). These data indicate a clinical significance of PEBP4 for predicting the tumor grade and the prognosis in patients with gliomas.

RKIP: much more than Raf kinase inhibitory protein

From its discovery as a phosphatidylethanolamine-binding protein in bovine brain to its designation as a physiological inhibitor of Raf kinase protein, RKIP has emerged as a critical molecule for maintaining subdued, well-orchestrated cellular responses to stimuli. The disruption of RKIP in a wide range of pathologies, including cancer, Alzheimer's disease, and pancreatitis, makes it an exciting target for individualized therapy and disease-specific interventions. This review attempts to highlight recent advances in the RKIP field underscoring its potential role as a master modulator of many pivotal intracellular signaling cascades that control cellular growth, motility, apoptosis, genomic integrity, and therapeutic resistance. Specific biological and functional niches are highlighted to focus future research towards an enhanced understanding of the multiple roles of RKIP in health and disease.

Phosphatidylenthanolamine Binding Protein aka Raf Kinase Inhibitor Protein: A Brief History of Its Discovery and the Remarkable Diversity of Biological Functions

Phosphatidylethanolamine-binding protein (PEBP) was identified almost three decades ago as an abundant protein in bovine brain. PEBP is the prototype of a highly conserved family of proteins represented in all three major phylogenetic divisions, eukaryota, bacteria, and archaea, with no significant sequence homology to other proteins. PEBP proteins have been studied in many species. The most thoroughly explored biological role of PEBP is that of a modulator of intracellular signaling pathways, which is mediated by its ability to bind and inhibit a number of protein kinases. The first such interaction that came to light was with the Raf1 kinase, and PEBP is thus widely referred to in the literature under its alternate name RKIP (Raf kinase inhibitory protein). The activity of RKIP itself is subject to regulation by phosphorylation. Intriguingly, PEBP has also been reported to possess additional, and diverse, biological functions unrelated to protein kinase networks that remain to be investigated in detail. Recent findings that RKIP may function as a suppressor of cancer metastasis are of great interest and importance. Prognostic and therapeutic applications of RKIP in human cancer were the subject of the first international workshop on RKIP that was held at the University of California, Los Angeles, in March 2010. This paper was presented at the workshop as a summary of the history of this still small but rapidly evolving field.

A transcriptional element of the diapause program in the Asian tiger mosquito, Aedes albopictus, identified by suppressive subtractive hybridization

Many temperate insects cope with the unfavorable conditions of winter by entering a photoperiodic diapause, but the molecular basis of this crucial adaptation is not well understood. In temperate populations of Aedes albopictus, exposure to short-day lengths causes the adult female to oviposit diapausing eggs. Suppressive subtractive hybridization (SSH) and quantitative reverse transcription PCR (qRT-PCR) were performed on RNA isolated from mature (stage V) oocytes of a temperate population of Ae. albopictus. A total of 438 inserts were sequenced from the SSH library and 324 unique (non-redundant) sequences were identified. QRT-PCR experiments were performed for 53 transcripts using a novel experimental design that included replicate temperate populations that do undergo photoperiodic diapause and replicate tropical populations that do not undergo a photoperiodic diapause. There was greater abundance of an epithelial membrane protein transcript under short-day versus long-day photoperiods in multiple temperate, but not tropical, populations. This gene may function during the diapause program by increasing desiccation resistance or energy reserves. The expression of a phosphatidylethanolamine-binding protein transcript in response to SD versus LD photoperiod differed between temperate and tropical populations but does not appear to be causally involved in diapause. Rapid Amplification of cDNA Ends (RACE) was performed to determine the entire cDNA sequence of both transcripts.

Unraveling the protective effect of a Drosophila phosphatidylethanolamine-binding protein upon bacterial infection by means of proteomics

This study addresses the biological function of CG18594, a Drosophila melanogaster phosphatidylethanolamine-binding protein (PEBP) that we named PEBP1, by combining fly genetics, survival experiments and differential proteomics. We demonstrate that transgenic flies overexpressing PEBP1 are highly protected against bacterial infection due to the release of immunity-related proteins in their hemolymph. Apart from proteins that have been reported earlier to participate in insect immunity, we also identify proteins involved in metabolism and signaling, and, in addition, twelve (hypothetical) proteins with unknown function. This is the first report demonstrating an immune function for a Drosophila PEBP protein.