Ephrin ligands and Eph receptors contribution to hematopoiesis

Genotype-Phenotype Models Predicting V̇O 2max Response to High-Intensity Interval Training in Physically Inactive Chinese

PURPOSE

This study aimed to analyze the interindividual differences of the maximal oxygen uptake (V̇O 2max ) response to 12 wk of high-intensity interval training (HIIT), and the genotype-phenotype models were constructed to predict the effect of HIIT on V̇O 2max .

METHODS

A total of 228 physically inactive adults who completed a 12-wk HIIT were analyzed. A genome-wide association study (GWAS) was conducted to identify genetic variants associated with the V̇O 2max response. Nonresponders, responders, and the highest training responders were defined as the effect sizes (ES) <0.2, ≥0.2, and ≥0.8, respectively. We generated polygenic predictor score (PPS) using lead variants and constructed a predictive model for V̇O 2max response based on a linear stepwise regression analysis.

RESULTS

The V̇O 2max increased significantly after HIIT (~14%, P < 0.001), but with interindividual differences (-7.8 to 17.9 mL·kg -1 ·min -1 ). In 27% of participants, the V̇O 2max showed no improvement. We identified one genetic locus near the γ-aminobutyric acid type A receptor subunit beta 3 gene ( GABRB3 , rs17116985) associated with V̇O 2max response at the genome-wide significance level ( P < 5 × 10 -8 ), and an additional nine single nucleotide polymorphisms (SNPs) at the suggestive significance level ( P < 1 × 10 -5 ). The SNPs rs474377, rs9365605, and rs17116985, respectively, explained 11%, 9%, and 6.2% of variance in V̇O 2max response. The 13 SNPs ( P < 1 × 10 -5 ) were found on chromosome 6 (position: 148209316-148223568). Individuals with a PPS greater than 1.757 had the highest response, and those with a PPS lower than -3.712 were nonresponders. The PPS, baseline V̇O 2max , sex, and body mass explained 56.4% of the variance in the V̇O 2max response; the major predictor was the PPS, which explained 39.4% of the variance.

CONCLUSIONS

The PPS, baseline V̇O 2max , sex, and body mass could explain the variance in V̇O 2max response. Individuals who had a PPS greater than 1.757 had the highest training response after 12 wk of HIIT. Genetic variants in a region on chromosome 6, especially the sterile alpha motif domain containing 5 gene ( SAMD5 ), which had been explored influencing angiogenesis, might have a potential role in the V̇O 2max response.

Impaired Repopulating Ability of Uhrf2-/- Hematopoietic Progenitor Cells in Mice

UHRF proteins catalyze the ubiquitination of target proteins and are involved in regulating gene expression. Some studies reported a reduced expression of UHRF2 in acute leukemia cells, but the role of UHRF2 in hematopoiesis remains unknown. Here, we generated Uhrf2-/- mice to clarify the role of UHRF2 deletion in hematopoiesis. Compared to Uhrf2+/+ mice, Uhrf2-/- mice showed no differences in complete blood counts, as well as bone marrow (BM) findings and spleen weights. Proportions of cells in progenitor fractions in BM were comparable between Uhrf2+/+ mice and Uhrf2-/- mice. However, in competitive repopulation assays with BM transplants (BMT), the proportions of Uhrf2-/- cells were decreased relative to Uhrf2+/+ cells in all lineages. After the second BMT, Uhrf2-/- neutrophils were few, while 20-30% of Uhrf2-/- T cells and B cells were still detected. RNA sequencing showed downregulation of some genes associated with stem-cell function in Uhrf2-/- hematopoietic stem/progenitor cells (HSPCs). Interestingly, trimethylated histone H3 lysine 9 was increased in Uhrf2-/- HSPCs in a cleavage under targets and tagmentation assay. While UHRF2 deletion did not cause hematologic malignancy or confer a growth advantage of HSPCs, our results suggest that UHRF2 may play a role in the regulation of hematopoiesis.

Kindlin2 enables EphB/ephrinB bi-directional signaling to support vascular development

Direct contact between cells expressing either ephrin ligands or Eph receptor tyrosine kinase produces diverse developmental responses. Transmembrane ephrinB ligands play active roles in transducing bi-directional signals downstream of EphB/ephrinB interaction. However, it has not been well understood how ephrinB relays transcellular signals to neighboring cells and what intracellular effectors are involved. Here, we report that kindlin2 can mediate bi-directional ephrinB signaling through binding to a highly conserved NIYY motif in the ephrinB2 cytoplasmic tail. We show this interaction is important for EphB/ephrinB-mediated integrin activation in mammalian cells and for blood vessel morphogenesis during zebrafish development. A mixed two-cell population study revealed that kindlin2 (in ephrinB2-expressing cells) modulates transcellular EphB4 activation by promoting ephrinB2 clustering. This mechanism is also operative for EphB2/ephrinB1, suggesting that kindlin2-mediated regulation is conserved for EphB/ephrinB signaling pathways. Together, these findings show that kindlin2 enables EphB4/ephrinB2 bi-directional signal transmission.

EphA4/ephrinA3 reverse signaling induced Müller cell gliosis and production of pro-inflammatory cytokines in experimental glaucoma

Previous work showed that ephrinA3/EphA4 forward signaling contributed to retinal ganglion cell (RGC) damage in experimental glaucoma. Since up-regulated patterns of ephrinA3 and EphA4 were observed in Müller cells and RGCs, an EphA4/ephrinA3 reverse signaling may exist in Müller cells of chronic ocular hypertension (COH) retina. We investigated effects of EphA4/ephrinA3 reverse signaling activation on Müller cells in COH retina. Intravitreal injection of the ephrinA3 agonist EphA4-Fc increased glial fibrillary acidic protein (GFAP) levels in normal retinas, suggestive of Müller cell gliosis, which was confirmed in purified cultured Müller cells treated with EphA4-Fc. These effects were mediated by intracellular STAT3 signaling pathway as phosphorylated STAT3 (p-STAT3) levels and ratios of p-STAT3/STAT3 were significantly increased in both COH retinas and EphA4-Fc intravitreally injected retinas, as well as in EphA4-Fc treated purified cultured Müller cells. The increase of GFAP protein levels in EphA4-Fc-injected retinas and EphA4-Fc treated purified cultured Müller cells could be partially eliminated by stattic, a selective STAT3 blocker. Co-immunoprecipitation results testified to the presence of interaction between ephrinA3 and STAT3/p-STAT3. In addition, intravitreal injection of EphA4-Fc or EphA4-Fc treatment of cultured Müller cells significantly up-regulated mRNA and protein contents of pro-inflammatory cytokines. Moreover, intravitreal injection of EphA4-Fc increased the number of apoptotic RGCs, which could be reversed by the tyrosine kinase blocker PP2. Overall, EphA4/ephrinA3 reverse signaling may induce Müller cell gliosis and increases release of pro-inflammatory factors, which could contribute to RGC death in glaucoma. Inhibition of EphA4/ephrinA3 signaling may provide an effective neuroprotection in glaucoma.

New Insight on 2D In Vitro Angiogenesis Models: All That Stretches Is Not a Tube

Highlights

Abstract

A Matrigel-based tube formation assay is a simple and widely accepted 2D angiogenesis model in vitro. Extracellular matrix (EM) proteins and growth factors (GFs) from Matrigel^TM exclusively trigger endothelial cell (EC) tubular network (ETN) formation. Co-culture of ECs with mesenchymal stromal cells (MSCs) is another and more reliable in vitro angiogenesis assay. MSCs modulate ETN formation through intercellular interactions and as a supplier of EM and GFs. The aim of the present study was to compare the expression profile of ECs in both models. We revealed upregulation of the uPA, uPAR, Jagged1, and Notch2 genes in dividing/migrating ECs and for ECs in both experimental models at 19 h. The expression of endothelial–mesenchymal transition genes largely increased in co-cultured ECs whereas Notch and Hippo signaling pathway genes were upregulated in ECs on Matrigel^TM. We showed that in the co-culture model, basement membrane (BM) deposition is limited only to cell-to-cell contacts in contrast to Matrigel^TM, which represents by itself fully pre-assembled BM matrix. We suggest that ETN in a co-culture model is still in a dynamic process due to immature BM whereas ECs in the Matrigel^TM assay seem to be at the final stage of ETN formation.

Slc20a1b is essential for hematopoietic stem/progenitor cell expansion in zebrafish

Hematopoietic stem and progenitor cells (HSPCs) are able to self-renew and can give rise to all blood lineages throughout their lifetime, yet the mechanisms regulating HSPC development have yet to be discovered. In this study, we characterized a hematopoiesis defective zebrafish mutant line named smu07, which was obtained from our previous forward genetic screening, and found the HSPC expansion deficiency in the mutant. Positional cloning identified that slc20a1b, which encodes a sodium phosphate cotransporter, contributed to the smu07 blood phenotype. Further analysis demonstrated that mutation of slc20a1b affects HSPC expansion through cell cycle arrest at G2/M phases in a cell-autonomous manner. Our study shows that slc20a1b is a vital regulator for HSPC proliferation in zebrafish early hematopoiesis and provides valuable insights into HSPC development.

Unveiling the Immunomodulatory Characteristics of Haemonchus contortus Ephrin Domain Containing Protein in the Parasite-Host Interactions

Simple Summary

Haemonchus contortus excretory/secretory products (HcESPs) contain many proteins that can perform various functions including modulating the host immune response. Recent studies indicate that IL-9 can be secreted by a specialized population of T cells called Th9 cells, which mediate anti-parasite immunity. Furthermore, HcESPs could enhance goat peripheral blood mononuclear cells (PBMCs) derived Th9 cells production. Ephrin domain containing protein (EPH) was identified as one of the HcESPs that can be isolated from different stages of this helminth. Nonetheless, the understanding of immunomodulatory roles of EPH on Th9 and other immune cells remains limited. In this study, the correlation between recombinant H. contortus Ephrin domain containing protein(rHcEPH)and goat PBMCs significantly enhanced Th9 cells differentiation, IL-9 expression, cell apoptosis efficiency, and cell migration, whereas cell proliferation was suppressed significantly depending on the concentration. Our findings illustrated that rHcEPH protein is linked to modulate the host immune cells and could enhance protective immunity by inducing Th9 cells secreted IL-9 in vitro.

Abstract

Ephrin domain containing protein (EPH), a significant excreted and secreted product (ESPs) of Haemonchus contortus, has been identified to have antigenic functions. Over the past years, a new subset of CD4 + T named as T helper 9 cells that secrete interleukin-9 (IL-9) as a signature cytokine is associated with tumor immunity and allergy. Nonetheless, the understanding of immunomodulatory roles of EPH on goat Th9 and other immune cells remains limited. Herein, EPH from H. contortus (HcEPH) was cloned and expressed in pET-28a. Immunofluorescence assay (IFA) was carried-out to localize rHcEPH within H. contortus adult worms and to bind with goat peripheral blood mononuclear cells (PBMCs). Besides, the impact of rHcEPH on signature cytokine IL-9 expression in goat PBMCs was evaluated. Flow cytometry was employed to examine Th9 cells production and cell apoptosis. The results revealed success in the expression and localization of rHcEPH in surface of adult H. contortus gut sections. According to IFA analysis, the rHcEPH protein was capable to react precisely with anti-H. contortus antibodies. Further functional analysis showed that correlation between rHcEPH and host PBMCs significantly enhanced Th9 cell differentiation, IL-9 expression, cell apoptosis efficiency, and cell migration, whereas cell proliferation was suppressed significantly depending on the concentration. Our observations indicated that rHcEPH protein is linked to modulate the host immune cells and could enhance protective immunity by inducing Th9 responses.

Highly multiplexed proteomic assessment of human bone marrow in acute myeloid leukemia

Acute myeloid leukemia (AML) is a genetically heterogeneous disease that is characterized by abnormal clonal proliferation of myeloid progenitor cells found predominantly within the bone marrow (BM) and blood. Recent studies suggest that genetic and phenotypic alterations in the BM microenvironment support leukemogenesis and allow leukemic cells to survive and evade chemotherapy-induced death. However, despite substantial evidence indicating the role of tumor-host interactions in AML pathogenesis, little is known about the complex microenvironment of the BM. To address this, we performed novel proteomic profiling of the noncellular compartment of the BM microenvironment in patients with AML (n = 10) and age- and sex-matched healthy control subjects (n = 10) using an aptamer-based, highly multiplexed, affinity proteomics platform (SOMAscan). We show that proteomic assessment of blood or RNA-sequencing of BM are suboptimal alternate screening strategies to determine the true proteomic composition of the extracellular soluble compartment of AML patient BM. Proteomic analysis revealed that 168 proteins significantly differed in abundance, with 91 upregulated and 77 downregulated in leukemic BM. A highly connected signaling network of cytokines and chemokines, including IL-8, was found to be the most prominent proteomic signature associated with AML in the BM microenvironment. We report the first description of significantly elevated levels of the myelosuppressive chemokine CCL23 (myeloid progenitor inhibitory factor-1) in both AML and myelodysplastic syndrome patients and perform functional experiments supportive of a role in the suppression of normal hematopoiesis. This unique paired RNA-sequencing and proteomics data set provides innovative mechanistic insights into AML and healthy aging and should serve as a useful public resource.

Harnessing the Power of Eph/ephrin Biosemiotics for Theranostic Applications

Comprehensive basic biological knowledge of the Eph/ephrin system in the physiologic setting is needed to facilitate an understanding of its role and the effects of pathological processes on its activity, thereby paving the way for development of prospective therapeutic targets. To this end, this review briefly addresses what is currently known and being investigated in order to highlight the gaps and possible avenues for further investigation to capitalize on their diverse potential.

EphB1 interaction with caveolin-1 in endothelial cells modulates caveolae biogenesis

Caveolae, the cave-like structures abundant in endothelial cells (ECs), are important for multiple signaling processes such as production of nitric oxide and caveolae-mediated intracellular trafficking. Using superresolution microscopy, fluorescence resonance energy transfer, and biochemical analysis, we observed that the EphB1 receptor tyrosine kinase constitutively interacts with caveolin-1 (Cav-1), the key structural protein of caveolae. Activation of EphB1 with its ligand Ephrin B1 induced EphB1 phosphorylation and the uncoupling EphB1 from Cav-1 and thereby promoted phosphorylation of Cav-1 by Src. Deletion of Cav-1 scaffold domain binding (CSD) motif in EphB1 prevented EphB1 binding to Cav-1 as well as Src-dependent Cav-1 phosphorylation, indicating the importance of CSD in the interaction. We also observed that Cav-1 protein expression and caveolae numbers were markedly reduced in ECs from EphB1-deficient (EphB1-/-) mice. The loss of EphB1 binding to Cav-1 promoted Cav-1 ubiquitination and degradation, and hence the loss of Cav-1 was responsible for reducing the caveolae numbers. These studies identify the crucial role of EphB1/Cav-1 interaction in the biogenesis of caveolae and in coordinating the signaling function of Cav-1 in ECs.

Ephrin/Eph receptor interaction facilitates macrophage recognition of differentiating human erythroblasts

Erythropoiesis is one of the most efficient cellular processes in the human body producing approximately 2.5 million red blood cells every second. This process occurs in a bone marrow niche comprised of a central resident macrophage surrounded by differentiating erythroblasts, termed an erythroblastic island. It is not known what initially attracts the macrophage to erythroblasts to form these islands. The ephrin/Eph receptor family are known to regulate heterophilic cell-cell adhesion. We find that human VCAM1⁺ and VCAM1^- bone marrow macrophages and in vitro cultured macrophages are ephrin-B2 positive, whereas differentiating human erythroblasts express EPHB4, EPHB6 and EPHA4. Furthermore, we detect a rise in integrin activation on erythroblasts at the stage at which the cells bind which is independent of EPH receptor presence. Using a live cell imaging assay, we show that specific inhibitory peptides or shRNA depletion of EPHB4 cause a significant reduction in the ability of macrophages to interact with erythroblasts but do not affect integrin activation. This study demonstrates for the first time that EPHB4 expression is required on erythroblasts to facilitate the initial recognition and subsequent interaction with macrophages, alongside the presence of active integrins.

UniPR1331, a small molecule targeting Eph/ephrin interaction, prolongs survival in glioblastoma and potentiates the effect of antiangiogenic therapy in mice

Glioblastoma multiforme (GBM) is the most malignant brain tumor, showing high resistance to standard therapeutic approaches that combine surgery, radiotherapy, and chemotherapy. As opposed to healthy tissues, EphA2 has been found highly expressed in specimens of glioblastoma, and increased expression of EphA2 has been shown to correlate with poor survival rates. Accordingly, agents blocking Eph receptor activity could represent a new therapeutic approach. Herein, we demonstrate that UniPR1331, a pan Eph receptor antagonist, possesses significant in vivo anti-angiogenic and anti-vasculogenic properties which lead to a significant anti-tumor activity in xenograft and orthotopic models of GBM. UniPR1331 halved the final volume of tumors when tested in xenografts (p<0.01) and enhanced the disease-free survival of treated animals in the orthotopic models of GBM both by using U87MG cells (40 vs 24 days of control, p<0.05) or TPC8 cells (52 vs 16 days, p<0.01). Further, the association of UniPR1331 with the anti-VEGF antibody Bevacizumab significantly increased the efficacy of both monotherapies in all tested models. Overall, our data promote UniPR1331 as a novel tool for tackling GBM.