Vitamin D3 Modulates Definitive Hematopoiesis by Two Distinct Mechanisms in the Developing Zebrafish Embryo

Abstract Abstract 763 Studies of the vitamin D3 signaling pathway have revealed a broad role for this hormone in tissue homeostasis and as a result there is great interest in exploring the therapeutic potential of vitamin D3 for the treatment of various diseases including cancer. Studies investigating the role of vitamin D3 in hematological malignancies have shown that in vitro vitamin D3 has anti-proliferative and pro-differentiation effects resulting in differentiation of leukemic cell lines towards the monocytic lineage. Surprisingly, the role of vitamin D3 in HSC homeostasis and leukemia progression in vivo is not well understood. To elucidate the mechanisms of action of vitamin D3 in vivo during HSC self-renewal and differentiation, we utilized the zebrafish (Danio rerio) as vertebrate model due to their evolutionary conserved blood system and their amenability for genetic and chemical manipulation. Vitamin D3 was identified in a chemical screen performed in our laboratory as a regulator of runx1 and c-myb expression in the aorta-gonad mesonephros (AGM), the first site of definitive hematopoiesis. Treatments of zebrafish embryos with active vitamin D3 (1,25OH D3) between 12–36 hours post fertilization (hpf) resulted in increased expression of HSC markers (runx1, c-myb, CD41) as determined by whole mount in situ hybridization (WISH). In contrast, treatment with the non-hydroxylated vitamin D3 precursor cholecalciferol (D3) resulted in decreased runx1 and c-myb expression. D3 treatment during HSC induction and expansion from 24–36 hpf did not affect runx1 and c-myb expression, suggesting that D3 is acting early during the establishment of the vascular niche. To quantify the difference in HSC progenitors observed by WISH, FACS analysis was performed on double positive Tg(Lmo2:dsRed), Tg(c-myb:gfp) embryos. 1,25OH D3 treated embryos had a 20% increase in the double positive cell population corresponding to HSCs, while treatment with D3 resulted in a 25% decrease in the number of HSCs. The differential effect of 1,25OH D3 and D3 suggest that these two compounds act via two distinct mechanisms. To determine if the HSC enhancement observed by 1,25OH D3 was acting through the canonical vitamin D3 receptor (VDR), loss of function experiments were performed by injecting morpholinos targeting the vitamin D receptors. Morpholino knockdown of VDRA and VDRB (zebrafish VDR orthologs) resulted in decreased expression of runx1 c-myb, and CD41 via WISH. The decrease in HSC positive cells was confirmed by fluorescence microscopy using the Tg(Runx1P2:gfp) and Tg(-6.0itga:gfp) reporter lines, further supporting our hypothesis. To address the decrease in HSCs by D3, we postulated that D3 was inhibiting hedgehog signaling, as vitamin D3 has been previously shown to act as a negative regulator of the hedgehog pathway. In support of our hypothesis, treatment with D3 resulted in decreased ptch2 mRNA expression a downstream target of hedgehog signaling. In addition, FACS analysis using the hedgehog reporter Tg(6xGli:mCherry) line showed a 15% reduction in the number of mCherry positive cells in D3 treated embryos compared to controls. Co-treatments of zebrafish embryos with the hedgehog antagonist cyclopamine and D3 resulted in additive loss of reporter activity (45%) and loss of runx1 positive cells in the AGM, revealing synergy between these two compounds. In addition, co-exposure with the hedgehog agonist SAG rescued the HSC defect in D3-treated embryos. Hedgehog signaling is known to regulate vein and artery specification through the activation of notch signaling. Consistent with our hypothesis that D3 reduces hedgehog signaling, an expansion of the venous marker flt4 and a reduction in the expression of the arterial marker ephrinb2a was observed by WISH on D3-treated embryos. Furthermore, treatment of the notch reporter line Tg(Notch:gfp) with D3 resulted in lowered notch activity. In summary, these studies reveal that the active 1,25OH D3 positively regulates HSC progenitors in vivo during the onset of definitive hematopoiesis. In contrast, the non-hydroxylated vitamin D3 precursor acts as negative regulator of hematopoiesis by inhibiting hedgehog signaling and affecting vascular niche formation. Based on our studies, the differential effect between D3 and 1,25OH D3 should be considered when investigating the therapeutic potential of vitamin D3 in the context of hematological malignancies and other cancers. Disclosures: Goessling: Fate Therapeutics: Consultancy. North:Fate Therapeutics: Consultancy.

Download Full-text

Ligand modulates the conversion of DNA-bound vitamin D3 receptor (VDR) homodimers into VDR-retinoid X receptor heterodimers

Molecular and Cellular Biology ◽

10.1128/mcb.14.5.3329-3338.1994 ◽

1994 ◽

Vol 14 (5) ◽

pp. 3329-3338

Author(s):

B Cheskis ◽

L P Freedman

Keyword(s):

Ligand Binding ◽

Vitamin D3 ◽

Hormone Receptors ◽

Steroid Receptors ◽

Dependent Manner ◽

D3 Receptor ◽

Vitamin D3 Receptor ◽

Binding Domains

Protein dimerization facilitates cooperative, high-affinity interactions with DNA. Nuclear hormone receptors, for example, bind either as homodimers or as heterodimers with retinoid X receptors (RXR) to half-site repeats that are stabilized by protein-protein interactions mediated by residues within both the DNA- and ligand-binding domains. In vivo, ligand binding among the subfamily of steroid receptors unmasks the nuclear localization and DNA-binding domains from a complex with auxiliary factors such as the heat shock proteins. However, the role of ligand is less clear among nuclear receptors, since they are constitutively localized to the nucleus and are presumably associated with DNA in the absence of ligand. In this study, we have begun to explore the role of the ligand in vitamin D3 receptor (VDR) function by examining its effect on receptor homodimer and heterodimer formation. Our results demonstrate that VDR is a monomer in solution; VDR binding to a specific DNA element leads to the formation of a homodimeric complex through a monomeric intermediate. We find that 1,25-dihydroxyvitamin D3, the ligand for VDR, decreases the amount of the DNA-bound VDR homodimer complex. It does so by significantly decreasing the rate of conversion of DNA-bound monomer to homodimer and at the same time enhancing the dissociation of the dimeric complex. This effectively stabilizes the bound monomeric species, which in turn serves to favor the formation of a VDR-RXR heterodimer. The ligand for RXR, 9-cis retinoic acid, has the opposite effect of destabilizing the heterodimeric-DNA complex. These results may explain how a nuclear receptor can bind DNA constitutively but still act to regulate transcription in a fully hormone-dependent manner.

Download Full-text

Molecular Basis for CCRL2 Regulation of Leukocyte Migration

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.615031 ◽

2020 ◽

Vol 8 ◽

Author(s):

Tiziana Schioppa ◽

Francesca Sozio ◽

Ilaria Barbazza ◽

Sara Scutera ◽

Daniela Bosisio ◽

...

Keyword(s):

Cancer Progression ◽

Chemokine Receptors ◽

Transmembrane Domain ◽

Nk Cell ◽

Structural Features ◽

Negative Regulator ◽

Leukocyte Migration ◽

Genetic Ablation

CCRL2 is a seven-transmembrane domain receptor that belongs to the chemokine receptor family. At difference from other members of this family, CCRL2 does not promote chemotaxis and shares structural features with atypical chemokine receptors (ACKRs). However, CCRL2 also differs from ACKRs since it does not bind chemokines and is devoid of scavenging functions. The only commonly recognized CCRL2 ligand is chemerin, a non-chemokine chemotactic protein. CCRL2 is expressed both by leukocytes and non-hematopoietic cells. The genetic ablation of CCRL2 has been instrumental to elucidate the role of this receptor as positive or negative regulator of inflammation. CCRL2 modulates leukocyte migration by two main mechanisms. First, when CCRL2 is expressed by barrier cells, such endothelial, and epithelial cells, it acts as a presenting molecule, contributing to the formation of a non-soluble chemotactic gradient for leukocytes expressing CMKLR1, the functional chemerin receptor. This mechanism was shown to be crucial in the induction of NK cell-dependent immune surveillance in lung cancer progression and metastasis. Second, by forming heterocomplexes with other chemokine receptors. For instance, CCRL2/CXCR2 heterodimers were shown to regulate the activation of β2-integrins in mouse neutrophils. This mini-review summarizes the current understanding of CCRL2 biology, based on experimental evidence obtained by the genetic deletion of this receptor in in vivo experimental models. Further studies are required to highlight the complex functional role of CCRL2 in different organs and pathological conditions.

Download Full-text

Selonsertib Alleviates the Progression of Rat Osteoarthritis: An in vitro and in vivo Study

Frontiers in Pharmacology ◽

10.3389/fphar.2021.687033 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jiyuan Yan ◽

Yingchi Zhang ◽

Gaohong Sheng ◽

Bowei Ni ◽

Yifan Xiao ◽

...

Keyword(s):

Therapeutic Potential ◽

Cartilage Damage ◽

Cartilage Degradation ◽

Degenerative Joint Disease ◽

Joint Disease ◽

Therapeutic Effects ◽

Exact Role

Osteoarthritis (OA) is a prevalent degenerative joint disease. Its development is highly associated with inflammatory response and apoptosis in chondrocytes. Selonsertib (Ser), the inhibitor of Apoptosis Signal-regulated kinase-1 (ASK1), has exhibited multiple therapeutic effects in several diseases. However, the exact role of Ser in OA remains unclear. Herein, we investigated the anti-arthritic effects as well as the potential mechanism of Ser on rat OA. Our results showed that Ser could markedly prevent the IL-1β-induced inflammatory reaction, cartilage degradation and cell apoptosis in rat chondrocytes. Meanwhile, the ASK1/P38/JNK and NFκB pathways were involved in the protective roles of Ser. Furthermore, intra-articular injection of Ser could significantly alleviate the surgery induced cartilage damage in rat OA model. In conclusion, our work provided insights into the therapeutic potential of Ser in OA, indicating that Ser might serve as a new avenue in OA treatment.

Download Full-text

Toll-Interacting Protein, Tollip, Inhibits IL-13-Mediated Pulmonary Eosinophilic Inflammation in Mice

Journal of Innate Immunity ◽

10.1159/000485850 ◽

2018 ◽

Vol 10 (2) ◽

pp. 106-118 ◽

Cited By ~ 4

Author(s):

Yoko Ito ◽

Niccolette Schaefer ◽

Amelia Sanchez ◽

David Francisco ◽

Rafeul Alam ◽

...

Keyword(s):

Lung Inflammation ◽

Negative Regulator ◽

Airflow Limitation ◽

Eosinophilic Inflammation ◽

Interacting Protein ◽

Proinflammatory Responses ◽

Cytokine Milieu ◽

Underlying Mechanisms

Toll-interacting protein (Tollip) is a key negative regulator of innate immunity by preventing excessive proinflammatory responses. Tollip genetic variation has been associated with airflow limitation in asthma subjects and Tollip expression. Whether Tollip regulates lung inflammation in a type 2 cytokine milieu (e.g., IL-13) is unclear. Our goal was to determine the in vivo role of Tollip in IL-13-mediated lung eosinophilic inflammation and the underlying mechanisms. Tollip-knockout (KO) and wild-type (WT) mice were inoculated intranasally with recombinant mouse IL-13 protein to examine lung inflammation. To determine how Tollip regulates inflammation, alveolar macrophages and bone marrow-derived macrophages from Tollip KO and WT mice were cultured with or without IL-13 and/or IL-33. IL-13-treated Tollip KO mice significantly increased lung eosinophilic inflammation and eotaxin-2 (CCL24) levels compared with the WT mice. IL-13- treated Tollip KO (vs. WT) macrophages, in the absence and particularly in the presence of IL-33, increased expression of the IL-33 receptor ST2L and CCL24, which was in part dependent on enhanced activation of interleukin (IL)-1 receptor-associated kinase 1 (IRAK1) and signal transducer and activator of transcription 6 (STAT6). Our results suggest that Tollip downregulates IL-13-mediated pulmonary eosinophilia in part through inhibiting the activity of the ST2L/IL-33/IRAK1 axis and STAT6.

Download Full-text

Abstract 1209: Interleukin-6 Reduces Myocardial Glucose Metabolism by Altering AMPK, Insulin Signaling, and PKC-𝛉 in Mice

Circulation ◽

10.1161/circ.116.suppl_16.ii_245-b ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Zhiyou Zhang ◽

Hwi Jin Ko ◽

Dae Young Jung ◽

Zhexi Ma ◽

Jason K Kim

Keyword(s):

Glucose Metabolism ◽

Insulin Signaling ◽

Insulin Action ◽

Cardiac Metabolism ◽

Negative Regulator ◽

Saline Control ◽

Myocardial Glucose Metabolism ◽

Peripheral Organs

Increasing evidence implicates the role of inflammation in the pathogenesis of diabetes and complications. Inflammatory cytokines (IL-6, TNF-α) are elevated in obese diabetic subjects, and are shown to modulate glucose metabolism in peripheral organs. In this report, we examined the effects of IL-6 on cardiac metabolism and insulin action in vivo. Male C57BL/6 mice were intravenously treated with IL-6 (16 ng/hr) or saline (control) for 2 hrs, and [ 14 C]2-deoxyglucose was intravenously injected in awake mice to measure myocardial glucose metabolism (n=9~10). Hyperinsulinemic-euglycemic clamps (2.5 mU/kg/min insulin infusion) were also performed in IL-6 or saline-treated mice (n=4~5) to measure cardiac insulin action. Acute treatment with IL-6 caused a 25% increase in myocardial STAT3 activity and significantly reduced basal myocardial glucose metabolism (Fig. 1 ; * P< 0.05). IL-6 treatment also reduced insulin-stimulated glucose uptake in heart, and these effects were associated with marked decreases in AMPK activity (Thr-phosphorylation of AMPK; Fig. 2 ) and IRS-1 tyrosine phosphorylation (Fig. 3 ). Acute IL-6 treatment increased myocardial expression of PKC-𝛉, which has been shown to mediate insulin resistance in peripheral organs (Fig. 4 ). These results indicate that IL-6 is a potent negative regulator of myocardial glucose metabolism and insulin action, and the underlying mechanism may involve IL-6 mediated activation of PKC-𝛉 and defects in AMPK and insulin signaling activity. Thus, our findings suggest a potential role of IL-6 in the pathogenesis of diabetic heart failure.

Download Full-text

Proof-of-concept clinical trial of etokimab shows a key role for IL-33 in atopic dermatitis pathogenesis

Science Translational Medicine ◽

10.1126/scitranslmed.aax2945 ◽

2019 ◽

Vol 11 (515) ◽

pp. eaax2945 ◽

Cited By ~ 29

Author(s):

Yi-Ling Chen ◽

Danuta Gutowska-Owsiak ◽

Clare S. Hardman ◽

Melanie Westmoreland ◽

Teena MacKenzie ◽

...

Keyword(s):

Atopic Dermatitis ◽

Therapeutic Potential ◽

Neutrophil Migration ◽

Neutrophil Infiltration ◽

Severity Index ◽

Fundamental Biology ◽

Targeted Inhibition

Targeted inhibition of cytokine pathways provides opportunities to understand fundamental biology in vivo in humans. The IL-33 pathway has been implicated in the pathogenesis of atopy through genetic and functional associations. We investigated the role of IL-33 inhibition in a first-in-class phase 2a study of etokimab (ANB020), an IgG1 anti–IL-33 monoclonal antibody, in patients with atopic dermatitis (AD). Twelve adult patients with moderate to severe AD received a single systemic administration of etokimab. Rapid and sustained clinical benefit was observed, with 83% achieving Eczema Area and Severity Index 50 (EASI50), and 33% EASI75, with reduction in peripheral eosinophils at day 29 after administration. We noted significant reduction in skin neutrophil infiltration after etokimab compared with placebo upon skin challenge with house dust mite, reactivity to which has been implicated in the pathogenesis of AD. We showed that etokimab also inhibited neutrophil migration to skin interstitial fluid in vitro. Besides direct effects on neutrophil migration, etokimab revealed additional unexpected CXCR1-dependent effects on IL-8–induced neutrophil migration. These human in vivo findings confirm an IL-33 upstream role in modulating skin inflammatory cascades and define the therapeutic potential for IL-33 inhibition in human diseases, including AD.

Download Full-text

Canonical Transient Receptor Potential (TRPC) 1 Acts as a Negative Regulator for Vanilloid TRPV6-mediated Ca2+ Influx

Journal of Biological Chemistry ◽

10.1074/jbc.m112.400952 ◽

2012 ◽

Vol 287 (42) ◽

pp. 35612-35620 ◽

Cited By ~ 36

Author(s):

Rainer Schindl ◽

Reinhard Fritsch ◽

Isaac Jardin ◽

Irene Frischauf ◽

Heike Kahr ◽

...

Keyword(s):

Transient Receptor Potential ◽

Receptor Potential ◽

Negative Regulator ◽

Hek293 Cells ◽

Current Voltage ◽

Repeat Domain ◽

Transient Receptor ◽

Current Voltage Relationship

TRP proteins mostly assemble to homomeric channels but can also heteromerize, preferentially within their subfamilies. The TRPC1 protein is the most versatile member and forms various TRPC channel combinations but also unique channels with the distantly related TRPP2 and TRPV4. We show here a novel cross-family interaction between TRPC1 and TRPV6, a Ca2+ selective member of the vanilloid TRP subfamily. TRPV6 exhibited substantial co-localization and in vivo interaction with TRPC1 in HEK293 cells, however, no interaction was observed with TRPC3, TRPC4, or TRPC5. Ca2+ and Na+ currents of TRPV6-overexpressing HEK293 cells are significantly reduced by co-expression of TRPC1, correlating with a dramatically suppressed plasma membrane targeting of TRPV6. In line with their intracellular retention, remaining currents of TRPC1 and TRPV6 co-expression resemble in current-voltage relationship that of TRPV6. Studying the N-terminal ankyrin like repeat domain, structurally similar in the two proteins, we have found that these cytosolic segments were sufficient to mediate a direct heteromeric interaction. Moreover, the inhibitory role of TRPC1 on TRPV6 influx was also maintained by expression of only its N-terminal ankyrin-like repeat domain. Our experiments provide evidence for a functional interaction of TRPC1 with TRPV6 that negatively regulates Ca2+ influx in HEK293 cells.

Download Full-text

Revealing the role of phospholipase Cβ3 in the regulation of VEGF-induced vascular permeability

Blood ◽

10.1182/blood-2012-03-417824 ◽

2012 ◽

Vol 120 (11) ◽

pp. 2167-2173 ◽

Cited By ~ 21

Author(s):

Luke H. Hoeppner ◽

Kathryn N. Phoenix ◽

Karl J. Clark ◽

Resham Bhattacharya ◽

Xun Gong ◽

...

Keyword(s):

Vascular Permeability ◽

Real Time ◽

Molecular Mechanisms ◽

Negative Regulator ◽

Transgenic Zebrafish ◽

Genetic Studies ◽

In Vivo Models ◽

Ischemic Diseases

AbstractVEGF induces vascular permeability (VP) in ischemic diseases and cancer, leading to many pathophysiological consequences. The molecular mechanisms by which VEGF acts to induce hyperpermeability are poorly understood and in vivo models that easily facilitate real-time, genetic studies of VP do not exist. In the present study, we report a heat-inducible VEGF transgenic zebrafish (Danio rerio) model through which VP can be monitored in real time. Using this approach with morpholino-mediated gene knock-down and knockout mice, we describe a novel role of phospholipase Cβ3 as a negative regulator of VEGF-mediated VP by regulating intracellular Ca2+ release. Our results suggest an important effect of PLCβ3 on VP and provide a new model with which to identify genetic regulators of VP crucial to several disease processes.

Download Full-text

Role of Toll-Like Receptors in Actuating Stem/Progenitor Cell Repair Mechanisms: Different Functions in Different Cells

Stem Cells International ◽

10.1155/2019/6795845 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 12

Author(s):

Fabio Sallustio ◽

Claudia Curci ◽

Alessandra Stasi ◽

Giuseppe De Palma ◽

Chiara Divella ◽

...

Keyword(s):

Progenitor Cells ◽

Therapeutic Potential ◽

Toll Like Receptors ◽

Repair Mechanisms ◽

Specific Tissue ◽

The Many ◽

Pathological Environment ◽

Molecular Patterns

Toll-like receptors (TLRs) represent one of the bridges that regulate the cross-talk between the innate and adaptive immune systems. TLRs interact with molecules shared and preserved by the pathogens of origin but also with endogenous molecules (damage/danger-associated molecular patterns (DAMPs)) that derive from injured tissues. This is probably why TLRs have been found to be expressed on several kinds of stem/progenitor cells (SCs). In these cells, the role of TLRs in the regulation of the basal motility, proliferation, differentiation processes, self-renewal, and immunomodulation has been demonstrated. In this review, we analyze the many different functions that the TLRs assume in SCs, pointing out that they can have different effects, depending on the background and on the kind of ligands that they recognize. Moreover, we discuss the TLR involvement in the response of SC to specific tissue damage and in the reparative processes, as well as how the identification of molecules mediating the differential function of TLR signaling could be decisive for the development of new therapeutic strategies. Considering the available studies on TLRs in SCs, here we address the importance of TLRs in sensing an injury by stem/progenitor cells and in determining their behavior and reparative activity, which is dependent on the conditions. Therefore, it could be conceivable that SCs employed in therapy could be potentially exposed to TLR ligands, which might modulate their therapeutic potential in vivo. In this context, to modulate SC proliferation, survival, migration, and differentiation in the pathological environment, we need to better understand the mechanisms of action of TLRs on SCs and learn how to control these receptors and their downstream pathways in a precise way. In this manner, in the future, cell therapy could be improved and made safer.

Download Full-text