Publications by authors named "Malith Karunasiri"

16 Publications

  • Page 1 of 1

Modulating endothelial cells with EGFL7 to diminish aGVHD after allogeneic bone marrow transplantation in mice.

Blood Adv 2021 Oct 15. Epub 2021 Oct 15.

Hopital Maisonneuve-Rosemont, Canada.

Acute graft versus host (aGVHD) is the second cause of death after allogeneic-hematopoietic stem cell transplant (allo-HSCT) underscoring the need for novel therapies. Based on previous work that endothelial cell dysfunction is present in aGVHD and that epidermal growth factor-like domain 7 (EGFL7) plays a significant role in decreasing inflammation by repressing endothelial cell activation and T cell migration, we hypothesized that increasing EGFL7 levels after allo-HSCT will diminish the severity of aGVHD. Here, we show that treatment with recombinant EGFL7 (rEGFL7) in two different murine models of aGVHD decreases aGVHD severity and improves survival in recipient mice after allogeneic transplantation with respect to controls without affecting graft versus leukemia effect. Furthermore, we showed that rEGFL7 treatment results in higher thymocytes, T, B and dendritic cells in recipient mice after allo-HSCT. This study constitutes a proof of concept of the ability of rEGFL7 therapy to reduce GHVD severity and mortality after allo-HSCT.
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http://dx.doi.org/10.1182/bloodadvances.2021005498DOI Listing
October 2021

Targeting Wnt signaling in acute myeloid leukemia stem cells.

Haematologica 2021 Sep 16. Epub 2021 Sep 16.

The Ohio State University Comprehensive Cancer Center, Columbus, OH, USA; Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH.

Not available.
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http://dx.doi.org/10.3324/haematol.2020.266155DOI Listing
September 2021

Targeting BRD4 in acute myeloid leukemia with partial tandem duplication of the gene.

Haematologica 2021 09 1;106(9):2527-2532. Epub 2021 Sep 1.

The Ohio State University, Comprehensive Cancer Center, Columbus, OH, USA; Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH.

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http://dx.doi.org/10.3324/haematol.2020.271627DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8409020PMC
September 2021

Spinal cord injury causes chronic bone marrow failure.

Nat Commun 2020 07 24;11(1):3702. Epub 2020 Jul 24.

Department of Neuroscience, The Ohio State University, Columbus, OH, USA.

Spinal cord injury (SCI) causes immune dysfunction, increasing the risk of infectious morbidity and mortality. Since bone marrow hematopoiesis is essential for proper immune function, we hypothesize that SCI disrupts bone marrow hematopoiesis. Indeed, SCI causes excessive proliferation of bone marrow hematopoietic stem and progenitor cells (HSPC), but these cells cannot leave the bone marrow, even after challenging the host with a potent inflammatory stimulus. Sequestration of HSPCs in bone marrow after SCI is linked to aberrant chemotactic signaling that can be reversed by post-injury injections of Plerixafor (AMD3100), a small molecule inhibitor of CXCR4. Even though Plerixafor liberates HSPCs and mature immune cells from bone marrow, competitive repopulation assays show that the intrinsic long-term functional capacity of HSPCs is still impaired in SCI mice. Together, our data suggest that SCI causes an acquired bone marrow failure syndrome that may contribute to chronic immune dysfunction.
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http://dx.doi.org/10.1038/s41467-020-17564-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382469PMC
July 2020

The long non-coding RNA HOXB-AS3 regulates ribosomal RNA transcription in NPM1-mutated acute myeloid leukemia.

Nat Commun 2019 11 25;10(1):5351. Epub 2019 Nov 25.

Center for RNA Medicine, Department of Clinical Medicine, Aalborg University, Copenhagen, Denmark.

Long non-coding RNAs (lncRNAs) are important regulatory molecules that are implicated in cellular physiology and pathology. In this work, we dissect the functional role of the HOXB-AS3 lncRNA in patients with NPM1-mutated (NPM1mut) acute myeloid leukemia (AML). We show that HOXB-AS3 regulates the proliferative capacity of NPM1mut AML blasts in vitro and in vivo. HOXB-AS3 is shown to interact with the ErbB3-binding protein 1 (EBP1) and guide EBP1 to the ribosomal DNA locus. Via this mechanism, HOXB-AS3 regulates ribosomal RNA transcription and de novo protein synthesis. We propose that in the context of NPM1 mutations, HOXB-AS3 overexpression acts as a compensatory mechanism, which allows adequate protein production in leukemic blasts.
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http://dx.doi.org/10.1038/s41467-019-13259-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6877618PMC
November 2019

EGFL7 Antagonizes NOTCH Signaling and Represents a Novel Therapeutic Target in Acute Myeloid Leukemia.

Clin Cancer Res 2020 02 31;26(3):669-678. Epub 2019 Oct 31.

The Ohio State University Comprehensive Cancer Center, Columbus, Ohio.

Purpose: EGF-like domain 7 (EGFL7) is a secreted protein and recently has been shown to play an important role in acute myeloid leukemia (AML); however, the underlying mechanism by which EGFL7 promotes leukemogenesis is largely unknown.

Experimental Design: Using an antibody interaction array, we measured the ability of EGFL7 to bind directly approximately 400 proteins expressed by primary AML blasts. Primary patient samples were stimulated with recombinant EGFL7 (rEGFL7) or anti-EGFL7 blocking antibody to assess alterations in downstream signaling and the ability to effect blast differentiation and survival. We treated three independent AML models with anti-EGFL7 or IgG1 control to determine whether anti-EGFL7 could prolong survival .

Results: We found EGFL7 significantly binds several signaling proteins important for normal and malignant hematopoiesis including NOTCH. Stimulation of AML blasts with rEGFL7 reduced NOTCH intracellular domain and NOTCH target gene expression while treatment with an anti-EGFL7 blocking antibody resulted in reactivation of NOTCH signaling, increased differentiation, and apoptosis. Competitive ligand-binding assays showed rEGFL7 inhibits DELTA-like (DLL) 4-mediated NOTCH activation while anti-EGFL7 combined with DLL4 significantly increased NOTCH activation and induced apoptosis. Using three different AML mouse models, we demonstrated that treatment with anti-EGFL7 alone results in increased survival.

Conclusions: Our data demonstrate that EGFL7 contributes to NOTCH silencing in AML by antagonizing canonical NOTCH ligand binding. Reactivation of NOTCH signaling using anti-EGFL7 results in prolonged survival of leukemic mice, supporting the use of EGFL7 as a novel therapeutic target in AML.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-2479DOI Listing
February 2020

Expression and functional relevance of long non-coding RNAs in acute myeloid leukemia stem cells.

Leukemia 2019 09 11;33(9):2169-2182. Epub 2019 Mar 11.

The Ohio State University Comprehensive Cancer Center, Columbus, OH, USA.

In acute myeloid leukemia (AML), novel therapies are needed to target not only the rapidly dividing AML blasts but also the distinct population of leukemia stem cells (LSCs), which have abnormal self-renewal capacity and increased chemotherapy resistance. Elucidation of the expression and function of deregulated genes in LSCs is critical to specifically target LSCs and may consequently lead to improving outcomes of AML patients. Here, we correlated long non-coding RNA (lncRNA) expression profiles obtained from two RNA-seq datasets of 375 younger (aged <60 years) 76 older (≥60 years) adults with cytogenetically normal AML with a 'core enriched' (CE) gene expression signature (GES) associated with LSCs. We identified a LSC-specific signature of 111 lncRNAs that correlated strongly with the CE-GES. Among the top upregulated LSC-associated lncRNAs, we identified the lncRNA DANCR. Further experiments confirmed that DANCR is upregulated in functionally validated LSC-enriched populations. DANCR knock-down in LSCs resulted in decreased stem-cell renewal and quiescence. Furthermore, we showed that targeting Dancr in vivo using a primary murine model of AML (expressing both Mll partial tandem duplication/Flt3 internal tandem duplication) prolonged the survival of mice after serial transplantation. Our data suggest that LSCs have a distinct lncRNA signature with functional relevance and therapeutic potential.
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http://dx.doi.org/10.1038/s41375-019-0429-5DOI Listing
September 2019

Knockout of both miR-15/16 loci induces acute myeloid leukemia.

Proc Natl Acad Sci U S A 2018 12 26;115(51):13069-13074. Epub 2018 Nov 26.

Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH 43210;

MicroRNAs (miRNAs) have been extensively reported to be associated with hematological malignancies. The loss of miR-15a/16-1 at chromosome 13q14 is a hallmark of most of human chronic lymphocytic leukemia (CLL). Deletion of murine miR-15a/16-1 and miR-15b/16-2 has been demonstrated to promote B cell malignancies. Here, we evaluate the biological role of miR-15/16 clusters, crossbreeding miR-15a/16-1 and miR-15b/16-2 knockout mice. Unexpectedly, the complete deletion of both clusters promoted myeloproliferative disorders in the majority of the mice by the age of 5 months with a penetrance of 70%. These mice showed a significant enlargement of spleen and abnormal swelling of lymph nodes. Flow cytometry characterization demonstrated an expanded CD11b/Gr-1 double-positive myeloid population both in spleen and in bone marrow. The transplantation of splenocytes harvested from double-KO mice into wild-type recipient mice resulted in the development of myeloproliferative disorders, as observed in the donors. In vivo, miR-15/16 cluster deletion up-regulated the expression of Cyclin D1, Cyclin D2, and Bcl-2. Taken together, our findings identify a driver oncogenic role for miR-15/16 cluster deletion in different leukocytic cell lineages.
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http://dx.doi.org/10.1073/pnas.1814980115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6304943PMC
December 2018

Prognostic and biological significance of the proangiogenic factor EGFL7 in acute myeloid leukemia.

Proc Natl Acad Sci U S A 2017 06 22;114(23):E4641-E4647. Epub 2017 May 22.

The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210;

Epithelial growth factor-like 7 (EGFL7) is a protein that is secreted by endothelial cells and plays an important role in angiogenesis. Although EGFL7 is aberrantly overexpressed in solid tumors, its role in leukemia has not been evaluated. Here, we report that levels of both mRNA and EGFL7 protein are increased in blasts of patients with acute myeloid leukemia (AML) compared with normal bone marrow cells. High mRNA expression associates with lower complete remission rates, and shorter event-free and overall survival in older (age ≥60 y) and younger (age <60 y) patients with cytogenetically normal AML. We further show that AML blasts secrete EGFL7 protein and that higher levels of EGFL7 protein are found in the sera from AML patients than in sera from healthy controls. Treatment of patient AML blasts with recombinant EGFL7 in vitro leads to increases in leukemic blast cell growth and levels of phosphorylated AKT. EGFL7 blockade with an anti-EGFL7 antibody reduced the growth potential and viability of AML cells. Our findings demonstrate that increased EGFL7 expression and secretion is an autocrine mechanism supporting growth of leukemic blasts in patients with AML.
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http://dx.doi.org/10.1073/pnas.1703142114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5468639PMC
June 2017

MG53-induced IRS-1 ubiquitination negatively regulates skeletal myogenesis and insulin signalling.

Nat Commun 2013 ;4:2354

Department of Life Sciences, Korea University, Seoul 136-701, Korea.

Mitsugumin 53 (MG53) negatively regulates skeletal myogenesis by targeting insulin receptor substrate 1 (IRS-1). Here, we show that MG53 is an ubiquitin E3 ligase that induces IRS-1 ubiquitination with the help of an E2-conjugating enzyme, UBE2H. Molecular manipulations that disrupt the E3-ligase function of MG53 abolish IRS-1 ubiquitination and enhance skeletal myogenesis. Skeletal muscles derived from the MG53-/- mice show an elevated IRS-1 level with enhanced insulin signalling, which protects the MG53-/- mice from developing insulin resistance when challenged with a high-fat/high-sucrose diet. Muscle samples derived from human diabetic patients and mice with insulin resistance show normal expression of MG53, indicating that altered MG53 expression does not serve as a causative factor for the development of metabolic disorders. Thus, therapeutic interventions that target the interaction between MG53 and IRS-1 may be a novel approach for the treatment of metabolic diseases that are associated with insulin resistance.
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http://dx.doi.org/10.1038/ncomms3354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941707PMC
April 2014

Insights into negative regulation by the glucocorticoid receptor from genome-wide profiling of inflammatory cistromes.

Mol Cell 2013 Jan 15;49(1):158-71. Epub 2012 Nov 15.

Gene Expression Laboratory, Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.

How the glucocorticoid receptor (GR) activates some genes while potently repressing others remains an open question. There are three current models for suppression: transrepression via GR tethering to AP-1/NF-κB sites, direct GR association with inhibitory elements (nGREs), and GR recruitment of the corepressor GRIP1. To gain insights into GR suppression, we used genomic analyses and genome-wide profiling of GR, p65, and c-Jun in LPS-stimulated macrophages. We show that GR mediates both activation and repression at tethered sites, GREs, and GRIP1-bound elements, indicating that motif classification is insufficient to predict regulatory polarity of GR binding. Interestingly, sites of GR repression utilize GRIP1's corepressor function and display reduced histone acetylation. Together, these findings suggest that while GR occupancy confers hormone responsiveness, the receptor itself may not participate in the regulatory effects. Furthermore, transcriptional outcome is not established by sequence but is influenced by epigenetic regulators, context, and other unrecognized regulatory determinants.
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http://dx.doi.org/10.1016/j.molcel.2012.10.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3640846PMC
January 2013

The Bcl6-SMRT/NCoR cistrome represses inflammation to attenuate atherosclerosis.

Cell Metab 2012 Apr 29;15(4):554-62. Epub 2012 Mar 29.

Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.

Chronic inflammation is a hallmark of atherosclerosis, but its transcriptional underpinnings are poorly understood. We show that the transcriptional repressor Bcl6 is an anti-inflammatory regulator whose loss in bone marrow of Ldlr(-/-) mice results in severe atherosclerosis and xanthomatous tendonitis, a virtually pathognomonic complication in patients with familial hypercholesterolemia. Disruption of the interaction between Bcl6 and SMRT or NCoR with a peptide inhibitor in vitro recapitulated atherogenic gene changes in mice transplanted with Bcl6-deficient bone marrow, pointing to these cofactors as key mediators of Bcl6 inflammatory suppression. Using ChIP-seq, we reveal the SMRT and NCoR corepressor cistromes, each consisting of over 30,000 binding sites with a nearly 50% overlap. While the complete cistromes identify a diversity of signaling pathways, the Bcl6-bound subcistromes for each corepressor are highly enriched for NF-κB-driven inflammatory and tissue remodeling genes. These results reveal that Bcl6-SMRT/NCoR complexes constrain immune responses and contribute to the prevention of atherosclerosis.
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http://dx.doi.org/10.1016/j.cmet.2012.02.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367511PMC
April 2012

Exercise and PGC-1α-independent synchronization of type I muscle metabolism and vasculature by ERRγ.

Cell Metab 2011 Mar;13(3):283-93

Gene Expression Laboratory, Salk Institute, La Jolla, CA 92037, USA.

How type I skeletal muscle inherently maintains high oxidative and vascular capacity in the absence of exercise is unclear. We show that nuclear receptor ERRγ is highly expressed in type I muscle and, when transgenically expressed in anaerobic type II muscles (ERRGO mice), dually induces metabolic and vascular transformation in the absence of exercise. ERRGO mice show increased expression of genes promoting fat metabolism, mitochondrial respiration, and type I fiber specification. Muscles in ERRGO mice also display an activated angiogenic program marked by myofibrillar induction and secretion of proangiogenic factors, neovascularization, and a 100% increase in running endurance. Surprisingly, the induction of type I muscle properties by ERRγ does not involve PGC-1α. Instead, ERRγ genetically activates the energy sensor AMPK in mediating the metabovascular changes in ERRGO mice. Therefore, ERRγ represents a previously unrecognized determinant that specifies intrinsic vascular and oxidative metabolic features that distinguish type I from type II muscle.
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http://dx.doi.org/10.1016/j.cmet.2011.01.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084588PMC
March 2011

Bcl-6 and NF-kappaB cistromes mediate opposing regulation of the innate immune response.

Genes Dev 2010 Dec 24;24(24):2760-5. Epub 2010 Nov 24.

Gene Expression Laboratory, Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.

In the macrophage, toll-like receptors (TLRs) are key sensors that trigger signaling cascades to activate inflammatory programs via the NF-κB gene network. However, the genomic network targeted by TLR/NF-κB activation and the molecular basis by which it is restrained to terminate activation and re-establish quiescence is poorly understood. Here, using chromatin immunoprecipitation sequencing (ChIP-seq), we define the NF-κB cistrome, which is comprised of 31,070 cis-acting binding sites responsive to lipopolysaccharide (LPS)-induced signaling. In addition, we demonstrate that the transcriptional repressor B-cell lymphoma 6 (Bcl-6) regulates nearly a third of the Tlr4-regulated transcriptome, and that 90% of the Bcl-6 cistrome is collapsed following Tlr4 activation. Bcl-6-deficient macrophages are acutely hypersensitive to LPS and, using comparative ChIP-seq analyses, we found that the Bcl-6 and NF-κB cistromes intersect, within nucleosomal distance, at nearly half of Bcl-6-binding sites in stimulated macrophages to promote opposing epigenetic modifications of the local chromatin. These results reveal a genomic strategy for controlling the innate immune response in which repressive and inductive cistromes establish a dynamic balance between macrophage quiescence and activation via epigenetically marked cis-regulatory elements.
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http://dx.doi.org/10.1101/gad.1998010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3003193PMC
December 2010
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