Targeting the actin nucleation promoting factor WASp provides a therapeutic approach for hematopoietic malignancies

AbstractCancer cells depend on actin cytoskeleton rearrangement to carry out hallmark malignant functions including activation, proliferation, migration and invasiveness. Wiskott–Aldrich Syndrome protein (WASp) is an actin nucleation-promoting factor and is a key regulator of actin polymerization in hematopoietic cells. The involvement of WASp in malignancies is incompletely understood. Since WASp is exclusively expressed in hematopoietic cells, we performed in silico screening to identify small molecule compounds (SMCs) that bind WASp and promote its degradation. We describe here one such identified molecule; this WASp-targeting SMC inhibits key WASp-dependent actin processes in several types of hematopoietic malignancies in vitro and in vivo without affecting naïve healthy cells. This small molecule demonstrates limited toxicity and immunogenic effects, and thus, might serve as an effective strategy to treat specific hematopoietic malignancies in a safe and precisely targeted manner.

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Small-Molecule Screen Identifies ROS as Key Regulators of Actin Dynamics in Neutrophils

Blood ◽

10.1182/blood.v112.11.4641.4641 ◽

2008 ◽

Vol 112 (11) ◽

pp. 4641-4641

Author(s):

Hidenori Hattori ◽

Kulandayan K Subramanian ◽

Hongbo R. Luo

Keyword(s):

Small Molecule ◽

Actin Polymerization ◽

Neutrophil Migration ◽

Physiological Role ◽

Leading Edge ◽

Actin Dynamics ◽

Functional Screening ◽

Cellular Processes

Abstract Precise spatial and temporal control of actin polymerization and depolymerization is essential for mediating various cellular processes such as migration, phagocytosis, vesicle trafficking and adhesion. In this study, we used a small-molecule functional screening approach to identify novel regulators of actin dynamics during neutrophil migration. Here we show that NADPH-oxidase dependent Reactive Oxygen Species act as negative regulators of actin polymerization. Neutrophils with pharmacologically inhibited oxidase or isolated from Chronic Granulomatous Disease (CGD) patient and mice displayed enhanced F-actin polymerization, multiple pseudopods formation and impaired chemotaxis. ROS localized to pseudopodia and inhibited actin polymerization by driving actin glutathionylation at the leading edge of migrating cells. Consistent with these in vitro results, adoptively transferred CGD murine neutrophils also showed impaired in vivo recruitment to sites of inflammation. Together, these results present a novel physiological role for ROS in regulation of action polymerization and shed new light on the pathogenesis of CGD.

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The WAVE2/Abi1 complex differentially regulates megakaryocyte development and spreading: implications for platelet biogenesis and spreading machinery

Blood ◽

10.1182/blood-2007-04-085860 ◽

2007 ◽

Vol 110 (10) ◽

pp. 3637-3647 ◽

Cited By ~ 36

Author(s):

Koji Eto ◽

Hidekazu Nishikii ◽

Takunori Ogaeri ◽

Shiro Suetsugu ◽

Akihide Kamiya ◽

...

Keyword(s):

Actin Polymerization ◽

Es Cells ◽

Embryonic Stem ◽

Striking Similarity ◽

Platelet Spreading ◽

Syndrome Protein ◽

Interfering Rna ◽

Lamellipodia Formation

Abstract Actin polymerization is crucial in throm-bopoiesis, platelet adhesion, and mega-karyocyte (MK) and platelet spreading. The Wiskott-Aldrich syndrome protein (WASp) homolog WAVE functions downstream of Rac and plays a pivotal role in lamellipodia formation. While MKs and platelets principally express WAVE1 and WAVE2, which are associated with Abi1, the physiologic significance of WAVE isoforms remains undefined. We generated WAVE2−/− embryonic stem (ES) cells because WAVE2-null mice die by embryonic day (E) 12.5. We found that while WAVE2−/− ES cells differentiated into immature MKs on OP9 stroma, they were severely impaired in terminal differentiation and in platelet production. WAVE2−/− MKs exhibited a defect in peripheral lamellipodia on fibrinogen even with phorbol 12-myristate 13-acetate (PMA) costimulation, indicating a requirement of WAVE2 for integrin αIIbβ3-mediated full spreading. MKs in which expression of Abi1 was reduced by small interfering RNA (siRNA) exhibited striking similarity to WAVE2−/− MKs in maturation and spreading. Interestingly, the knockdown of IRSp53, a Rac effector that preferentially binds to WAVE2, impaired the development of lamellipodia without affecting proplatelet production. In contrast, thrombopoiesis in vivo and platelet spreading on fibrinogen in vitro were intact in WAVE1-null mice. These observations clarify indispensable roles for the WAVE2/Abi1 complex in αIIbβ3-mediated lamellipodia by MKs and platelets through Rac and IRSp53, and additionally in thrombopoiesis independent of Rac and IRSp53.

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Small-molecule agonists of SHIP1 inhibit the phosphoinositide 3-kinase pathway in hematopoietic cells

Blood ◽

10.1182/blood-2007-03-079699 ◽

2007 ◽

Vol 110 (6) ◽

pp. 1942-1949 ◽

Cited By ~ 90

Author(s):

Christopher J. Ong ◽

Andrew Ming-Lum ◽

Matt Nodwell ◽

Ali Ghanipour ◽

Lu Yang ◽

...

Keyword(s):

Small Molecule ◽

Hematopoietic Cells ◽

Pi3k Pathway ◽

Cellular Activation ◽

Phosphoinositide 3 Kinase ◽

Identification And Characterization ◽

Kinase Pathway

Abstract Because phosphoinositide 3-kinase (PI3K) plays a central role in cellular activation, proliferation, and survival, pharmacologic inhibitors targeting components of the PI3K pathway are actively being developed as therapeutics for the treatment of inflammatory disorders and cancer. These targeted drugs inhibit the activity of either PI3K itself or downstream protein kinases. However, a previously unexplored, alternate strategy is to activate the negative regulatory phosphatases in this pathway. The SH2-containing inositol-5′-phosphatase SHIP1 is a normal physiologic counter-regulator of PI3K in immune/hematopoietic cells that hydrolyzes the PI3K product phosphatidylinositiol-3,4,5-trisphosphate (PIP3). We now describe the identification and characterization of potent and specific small-molecule activators of SHIP1. These compounds represent the first small-molecule activators of a phosphatase, and are able to activate recombinant SHIP1 enzyme in vitro and stimulate SHIP1 activity in intact macrophage and mast cells. Mechanism of activation studies with these compounds suggest that they bind a previously undescribed, allosteric activation domain within SHIP1. Furthermore, in vivo administration of these compounds was protective in mouse models of endotoxemia and acute cutaneous anaphylaxis, suggesting that SHIP1 agonists could be used therapeutically to inhibit the PI3K pathway.

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Faculty Opinions recommendation of Identification of new small molecule inhibitors of cystic fibrosis transmembrane conductance regulator protein: in vitro and in vivo studies.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1069767.522696 ◽

2007 ◽

Author(s):

Kim Barrett

Keyword(s):

Cystic Fibrosis ◽

Small Molecule ◽

Small Molecule Inhibitors ◽

In Vivo Studies ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Regulator Protein ◽

Cystic Fibrosis Transmembrane

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A small molecule HIF-1α stabilizer that accelerates diabetic wound healing

Nature Communications ◽

10.1038/s41467-021-23448-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Guodong Li ◽

Chung-Nga Ko ◽

Dan Li ◽

Chao Yang ◽

Wanhe Wang ◽

...

Keyword(s):

Wound Healing ◽

Small Molecule ◽

Hypoxia Inducible Factor ◽

Diabetic Patients ◽

Diabetic Mice ◽

Impaired Wound Healing ◽

Von Hippel Lindau ◽

Design And Synthesis

AbstractImpaired wound healing and ulcer complications are a leading cause of death in diabetic patients. In this study, we report the design and synthesis of a cyclometalated iridium(III) metal complex 1a as a stabilizer of hypoxia-inducible factor-1α (HIF-1α). In vitro biophysical and cellular analyses demonstrate that this compound binds to Von Hippel-Lindau (VHL) and inhibits the VHL–HIF-1α interaction. Furthermore, the compound accumulates HIF-1α levels in cellulo and activates HIF-1α mediated gene expression, including VEGF, GLUT1, and EPO. In in vivo mouse models, the compound significantly accelerates wound closure in both normal and diabetic mice, with a greater effect being observed in the diabetic group. We also demonstrate that HIF-1α driven genes related to wound healing (i.e. HSP-90, VEGFR-1, SDF-1, SCF, and Tie-2) are increased in the wound tissue of 1a-treated diabetic mice (including, db/db, HFD/STZ and STZ models). Our study demonstrates a small molecule stabilizer of HIF-1α as a promising therapeutic agent for wound healing, and, more importantly, validates the feasibility of treating diabetic wounds by blocking the VHL and HIF-1α interaction.

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Targeting RECQL5 Functions, by a Small Molecule, Selectively Kills Breast Cancer in Vitro and in Vivo

Journal of Medicinal Chemistry ◽

10.1021/acs.jmedchem.0c01692 ◽

2021 ◽

Vol 64 (3) ◽

pp. 1524-1544

Author(s):

Saikat Chakraborty ◽

Kartik Dutta ◽

Pooja Gupta ◽

Anubrata Das ◽

Amit Das ◽

...

Keyword(s):

Breast Cancer ◽

Small Molecule

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Primitive Human Hematopoietic Cells Are Enriched in Cord Blood Compared With Adult Bone Marrow or Mobilized Peripheral Blood as Measured by the Quantitative In Vivo SCID-Repopulating Cell Assay

Blood ◽

10.1182/blood.v89.11.3919 ◽

1997 ◽

Vol 89 (11) ◽

pp. 3919-3924 ◽

Cited By ~ 328

Author(s):

Jean C.Y. Wang ◽

Monica Doedens ◽

John E. Dick

Keyword(s):

Bone Marrow ◽

Cord Blood ◽

Peripheral Blood ◽

Hematopoietic Cells ◽

Allogeneic Transplantation ◽

Functional Assay ◽

Hematopoietic Stem ◽

Mobilized Peripheral Blood

Abstract We have previously reported the development of in vivo functional assays for primitive human hematopoietic cells based on their ability to repopulate the bone marrow (BM) of severe combined immunodeficient (SCID) and nonobese diabetic/SCID (NOD/SCID) mice following intravenous transplantation. Accumulated data from gene marking and cell purification experiments indicate that the engrafting cells (defined as SCID-repopulating cells or SRC) are biologically distinct from and more primitive than most cells that can be assayed in vitro. Here we demonstrate through limiting dilution analysis that the NOD/SCID xenotransplant model provides a quantitative assay for SRC. Using this assay, the frequency of SRC in cord blood (CB) was found to be 1 in 9.3 × 105 cells. This was significantly higher than the frequency of 1 SRC in 3.0 × 106 adult BM cells or 1 in 6.0 × 106 mobilized peripheral blood (PB) cells from normal donors. Mice transplanted with limiting numbers of SRC were engrafted with both lymphoid and multilineage myeloid human cells. This functional assay is currently the only available method for quantitative analysis of human hematopoietic cells with repopulating capacity. Both CB and mobilized PB are increasingly being used as alternative sources of hematopoietic stem cells in allogeneic transplantation. Thus, the findings reported here will have important clinical as well as biologic implications.

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Neuropilin-1 on hematopoietic cells as a source of vascular development

Blood ◽

10.1182/blood-2002-01-0119 ◽

2003 ◽

Vol 101 (5) ◽

pp. 1801-1809 ◽

Cited By ~ 35

Author(s):

Yoshihiro Yamada ◽

Yuichi Oike ◽

Hisao Ogawa ◽

Yasuhiro Ito ◽

Hajime Fujisawa ◽

...

Keyword(s):

Endothelial Cells ◽

Fetal Liver ◽

Vascular Development ◽

Hematopoietic Cells ◽

Vegf Receptor ◽

Knock Out ◽

Neuropilin 1 ◽

Vasculogenesis And Angiogenesis

Neuropilin-1 (NP-1) is a receptor for vascular endothelial growth factor-165 (VEGF165) and acts as a coreceptor that enhances the function of VEGF165 through VEGF receptor-2 (VEGFR-2). Studies using transgenic and knock-out mice of NP-1 indicated that this molecule is important for vascular development as well as neuronal development. We recently reported that clustered soluble NP-1 phosphorylates VEGFR-2 on endothelial cells with a low dose of VEGF165 and rescues the defective vascularity of the NP-1−/− embryo in vitro and in vivo. Here we show that NP-1 is expressed by CD45+ hematopoietic cells in the fetal liver, can bind VEGF165, and phosphorylates VEGFR-2 on endothelial cells. CD45+NP-1+ cells rescued the defective vasculogenesis and angiogenesis in the NP-1−/− P-Sp (para-aortic splanchnopleural mesodermal region) culture, although CD45+NP-1− cells did not. Moreover, CD45+NP-1+ cells together with VEGF165 induced angiogenesis in an in vivo Matrigel assay and cornea neovascularization assay. The extracellular domain of NP-1 consists of “a,” “b,” and “c” domains, and it is known that the “a” and “c” domains are necessary for dimerization of NP-1. We found that both the “a” and “c” domains are essential for such rescue of defective vascularities in the NP-1 mutant. These results suggest that NP-1 enhances vasculogenesis and angiogenesis exogenously and that dimerization of NP-1 is important for enhancing vascular development. In NP-1−/− embryos, vascular sprouting is impaired at the central nervous system (CNS) and pericardium where VEGF is not abundant, indicating that NP-1–expressing cells are required for normal vascular development.

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Isolation in a single step of a highly enriched murine hematopoietic stem cell population with competitive long-term repopulating ability

Blood ◽

10.1182/blood.v74.3.930.930 ◽

1989 ◽

Vol 74 (3) ◽

pp. 930-939 ◽

Cited By ~ 49

Author(s):

SJ Szilvassy ◽

PM Lansdorp ◽

RK Humphries ◽

AC Eaves ◽

CJ Eaves

Keyword(s):

Simple Procedure ◽

Hematopoietic Cells ◽

Stem Cell Population ◽

Proliferative Potential ◽

Vitro Assay ◽

Hematopoietic Stem ◽

Marrow Cells

Abstract A simple procedure is described for the quantitation and enrichment of murine hematopoietic cells with the capacity for long-term repopulation of lymphoid and myeloid tissues in lethally irradiated mice. To ensure detection of the most primitive marrow cells with this potential, we used a competitive assay in which female recipients were injected with male “test” cells and 1 to 2 x 10(5) “compromised” female marrow cells with normal short-term repopulating ability, but whose long-term repopulating ability had been reduced by serial transplantation. Primitive hematopoietic cells were purified by flow cytometry and sorting based on their forward and orthogonal light-scattering properties, and Thy-1 and H-2K antigen expression. Enrichment profiles for normal marrow, and marrow of mice injected with 5-fluorouracil (5- FU) four days previously, were established for each of these parameters using an in vitro assay for high proliferative potential, pluripotent colony-forming cells. When all four parameters were gated simultaneously, these clonogenic cells were enriched 100-fold. Both day 9 and day 12 CFU-S were copurified; however, the purity (23%) and enrichment (75-fold) of day 12 CFU-S in the sorted population was greater with 5-FU-treated cells. Five hundred of the sorted 5-FU marrow cells consistently repopulated recipient lymphoid and myeloid tissues (greater than 50% male, 1 to 3 months post-transplant) when co-injected with 1 to 2 x 10(5) compromised female marrow cells, and approximately 100 were sufficient to achieve the same result in 50% of recipients under the same conditions. This relatively simple purification and assay strategy should facilitate further analysis of the heterogeneity and regulation of stem cells that maintain hematopoiesis in vivo.

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Rho-Proteins and Downstream Pathways as Potential Targets in Sepsis and Septic Shock: What Have We Learned from Basic Research

Cells ◽

10.3390/cells10081844 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1844

Author(s):

Maria Luísa da Silveira Hahmeyer ◽

José Eduardo da Silva-Santos

Keyword(s):

Septic Shock ◽

Actin Polymerization ◽

Current Knowledge ◽

Cecal Ligation ◽

Experimental Models ◽

Rho Proteins ◽

Growing Cell ◽

Sepsis And Septic Shock

Sepsis and septic shock are associated with acute and sustained impairment in the function of the cardiovascular system, kidneys, lungs, liver, and brain, among others. Despite the significant advances in prevention and treatment, sepsis and septic shock sepsis remain global health problems with elevated mortality rates. Rho proteins can interact with a considerable number of targets, directly affecting cellular contractility, actin filament assembly and growing, cell motility and migration, cytoskeleton rearrangement, and actin polymerization, physiological functions that are intensively impaired during inflammatory conditions, such as the one that occurs in sepsis. In the last few decades, Rho proteins and their downstream pathways have been investigated in sepsis-associated experimental models. The most frequently used experimental design included the exposure to bacterial lipopolysaccharide (LPS), in both in vitro and in vivo approaches, but experiments using the cecal ligation and puncture (CLP) model of sepsis have also been performed. The findings described in this review indicate that Rho proteins, mainly RhoA and Rac1, are associated with the development of crucial sepsis-associated dysfunction in different systems and cells, including the endothelium, vessels, and heart. Notably, the data found in the literature suggest that either the inhibition or activation of Rho proteins and associated pathways might be desirable in sepsis and septic shock, accordingly with the cellular system evaluated. This review included the main findings, relevance, and limitations of the current knowledge connecting Rho proteins and sepsis-associated experimental models.

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