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Kartchner D, McCoy K, Dubey J, Zhang D, Zheng K, Umrani R, Kim JJ, Mitchell CS. Literature-Based Discovery to Elucidate the Biological Links between Resistant Hypertension and COVID-19. BIOLOGY 2023; 12:1269. [PMID: 37759668 PMCID: PMC10526006 DOI: 10.3390/biology12091269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/11/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023]
Abstract
Multiple studies have reported new or exacerbated persistent or resistant hypertension in patients previously infected with COVID-19. We used literature-based discovery to identify and prioritize multi-scalar explanatory biology that relates resistant hypertension to COVID-19. Cross-domain text mining of 33+ million PubMed articles within a comprehensive knowledge graph was performed using SemNet 2.0. Unsupervised rank aggregation determined which concepts were most relevant utilizing the normalized HeteSim score. A series of simulations identified concepts directly related to COVID-19 and resistant hypertension or connected via one of three renin-angiotensin-aldosterone system hub nodes (mineralocorticoid receptor, epithelial sodium channel, angiotensin I receptor). The top-ranking concepts relating COVID-19 to resistant hypertension included: cGMP-dependent protein kinase II, MAP3K1, haspin, ral guanine nucleotide exchange factor, N-(3-Oxododecanoyl)-L-homoserine lactone, aspartic endopeptidases, metabotropic glutamate receptors, choline-phosphate cytidylyltransferase, protein tyrosine phosphatase, tat genes, MAP3K10, uridine kinase, dicer enzyme, CMD1B, USP17L2, FLNA, exportin 5, somatotropin releasing hormone, beta-melanocyte stimulating hormone, pegylated leptin, beta-lipoprotein, corticotropin, growth hormone-releasing peptide 2, pro-opiomelanocortin, alpha-melanocyte stimulating hormone, prolactin, thyroid hormone, poly-beta-hydroxybutyrate depolymerase, CR 1392, BCR-ABL fusion gene, high density lipoprotein sphingomyelin, pregnancy-associated murine protein 1, recQ4 helicase, immunoglobulin heavy chain variable domain, aglycotransferrin, host cell factor C1, ATP6V0D1, imipramine demethylase, TRIM40, H3C2 gene, COL1A1+COL1A2 gene, QARS gene, VPS54, TPM2, MPST, EXOSC2, ribosomal protein S10, TAP-144, gonadotropins, human gonadotropin releasing hormone 1, beta-lipotropin, octreotide, salmon calcitonin, des-n-octanoyl ghrelin, liraglutide, gastrins. Concepts were mapped to six physiological themes: altered endocrine function, 23.1%; inflammation or cytokine storm, 21.3%; lipid metabolism and atherosclerosis, 17.6%; sympathetic input to blood pressure regulation, 16.7%; altered entry of COVID-19 virus, 14.8%; and unknown, 6.5%.
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Affiliation(s)
- David Kartchner
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Kevin McCoy
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Janhvi Dubey
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Dongyu Zhang
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Kevin Zheng
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Rushda Umrani
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- College of Computing, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James J. Kim
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Cassie S. Mitchell
- Laboratory for Pathology Dynamics, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Center for Machine Learning at Georgia Tech, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Moghadam AR, Patrad E, Tafsiri E, Peng W, Fangman B, Pluard TJ, Accurso A, Salacz M, Shah K, Ricke B, Bi D, Kimura K, Graves L, Najad MK, Dolatkhah R, Sanaat Z, Yazdi M, Tavakolinia N, Mazani M, Amani M, Ghavami S, Gartell R, Reilly C, Naima Z, Esfandyari T, Farassati F. Ral signaling pathway in health and cancer. Cancer Med 2017; 6:2998-3013. [PMID: 29047224 PMCID: PMC5727330 DOI: 10.1002/cam4.1105] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 04/10/2017] [Accepted: 04/14/2017] [Indexed: 12/12/2022] Open
Abstract
The Ral (Ras-Like) signaling pathway plays an important role in the biology of cells. A plethora of effects is regulated by this signaling pathway and its prooncogenic effectors. Our team has demonstrated the overactivation of the RalA signaling pathway in a number of human malignancies including cancers of the liver, ovary, lung, brain, and malignant peripheral nerve sheath tumors. Additionally, we have shown that the activation of RalA in cancer stem cells is higher in comparison with differentiated cancer cells. In this article, we review the role of Ral signaling in health and disease with a focus on the role of this multifunctional protein in the generation of therapies for cancer. An improved understanding of this pathway can lead to development of a novel class of anticancer therapies that functions on the basis of intervention with RalA or its downstream effectors.
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Affiliation(s)
- Adel Rezaei Moghadam
- Department of Human Anatomy and Cell ScienceUniversity of ManitobaWinnipegCanada
| | - Elham Patrad
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Elham Tafsiri
- Department of Pediatrics, Columbia Presbyterian Medical CenterNew YorkNew York
| | - Warner Peng
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Benjamin Fangman
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Timothy J Pluard
- Saint Luke's HospitalUniversity of Missouri at Kansas CityKansas CityMissouri
| | - Anthony Accurso
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Michael Salacz
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Kushal Shah
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Brandon Ricke
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Danse Bi
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Kyle Kimura
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Leland Graves
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Marzieh Khajoie Najad
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Roya Dolatkhah
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Zohreh Sanaat
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Mina Yazdi
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Naeimeh Tavakolinia
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Mohammad Mazani
- Pasteur Institute of IranTehranIran
- Ardabil University of Medical Sciences, BiochemistryArdabilIran
| | - Mojtaba Amani
- Pasteur Institute of IranTehranIran
- Ardabil University of Medical Sciences, BiochemistryArdabilIran
| | - Saeid Ghavami
- Department of Human Anatomy and Cell ScienceUniversity of ManitobaWinnipegCanada
| | - Robyn Gartell
- Department of Pediatrics, Columbia Presbyterian Medical CenterNew YorkNew York
| | - Colleen Reilly
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Zaid Naima
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Tuba Esfandyari
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Faris Farassati
- Research Service (151)Kansas City Veteran Affairs Medical Center & Midwest Biomedical Research Foundation4801 E Linwood BlvdKansas CityMissouri64128‐2226
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Janardhan SV, Marks R, Gajewski TF. Primary murine CD4+ T cells fail to acquire the ability to produce effector cytokines when active Ras is present during Th1/Th2 differentiation. PLoS One 2014; 9:e112831. [PMID: 25397617 PMCID: PMC4232516 DOI: 10.1371/journal.pone.0112831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 10/16/2014] [Indexed: 01/10/2023] Open
Abstract
Constitutive Ras signaling has been shown to augment IL-2 production, reverse anergy, and functionally replace many aspects of CD28 co-stimulation in CD4+ T cells. These data raise the possibility that introduction of active Ras into primary T cells might result in improved functionality in pathologic situations of T cell dysfunction, such as cancer or chronic viral infection. To test the biologic effects of active Ras in primary T cells, CD4+ T cells from Coxsackie-Adenovirus Receptor Transgenic mice were transduced with an adenovirus encoding active Ras. As expected, active Ras augmented IL-2 production in naive CD4+ T cells. However, when cells were cultured for 4 days under conditions to promote effector cell differentiation, active Ras inhibited the ability of CD4+ T cells to acquire a Th1 or Th2 effector cytokine profile. This differentiation defect was not due to deficient STAT4 or STAT6 activation by IL-12 or IL-4, respectively, nor was it associated with deficient induction of T-bet and GATA-3 expression. Impaired effector cytokine production in active Ras-transduced cells was associated with deficient demethylation of the IL-4 gene locus. Our results indicate that, despite augmenting acute activation of naïve T cells, constitutive Ras signaling inhibits the ability of CD4+ T cells to properly differentiate into Th1/Th2 effector cytokine-producing cells, in part by interfering with epigenetic modification of effector gene loci. Alternative strategies to potentiate Ras pathway signaling in T cells in a more regulated fashion should be considered as a therapeutic approach to improve immune responses in vivo.
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Affiliation(s)
- Sujit V. Janardhan
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Reinhard Marks
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Thomas F. Gajewski
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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Kiel C, Verschueren E, Yang JS, Serrano L. Integration of Protein Abundance and Structure Data Reveals Competition in the ErbB Signaling Network. Sci Signal 2013; 6:ra109. [DOI: 10.1126/scisignal.2004560] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Fredericks J, Ren R. The role of RAS effectors in BCR/ABL induced chronic myelogenous leukemia. Front Med 2013; 7:452-61. [PMID: 24264166 DOI: 10.1007/s11684-013-0304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 10/16/2013] [Indexed: 01/08/2023]
Abstract
BCR/ABL is the causative agent of chronic myelogenous leukemia (CML). Through structure/function analysis, several protein motifs have been determined to be important for the development of leukemogenesis. Tyrosine177 of BCR is a Grb2 binding site required for BCR/ABL-induced CML in mice. In the current study, we use a mouse bone marrow transduction/transplantation system to demonstrate that addition of oncogenic NRAS (NRASG12D) to a vector containing a BCR/ABL(Y177F) mutant "rescues" the CML phenotype rapidly and efficiently. To further narrow down the pathways downstream of RAS that are responsible for this rescue effect, we utilize well-characterized RAS effector loop mutants and determine that the RAL pathway is important for rapid induction of CML. Inhibition of this pathway by a dominant negative RAL is capable of delaying disease progression. Results from the present study support the notion of RAL inhibition as a potential therapy for BCR/ABL-induced CML.
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Affiliation(s)
- Jessica Fredericks
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
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6
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Abstract
Recognition that Ral guanine nucleotide exchange factors (RalGEFs) are direct Ras effectors and that Ral G-protein activation is a direct consequence of Ras activation has spurred focused efforts to establish the contribution of RalGEF/Ral signaling to oncogenic transformation. Here, we provide a broad-strokes overview of the mechanistic organization of the RalGEF/Ral signaling network, evaluate the evidence for participation of this network in tumorigenic regulatory milieus, consider targeting strategies, and discuss the challenges to and opportunities for clinical development of these targeting strategies.
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Affiliation(s)
- Jonathan M Cooper
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Brian O Bodemann
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Michael A White
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas, USA.
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7
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Le Pogam C, Krief P, Beurlet S, Soulié A, Balitrand N, Cassinat B, Cavé H, Kosmider O, Setterblad N, Leboeuf C, Sarda-Mantel L, Hervatin F, Merlet P, Noguera ME, Janin A, Pla M, Fontenay M, Adès L, Fenaux P, Chomienne C, Padua RA, Omidvar N. Localization of the NRAS:BCL-2 complex determines anti-apoptotic features associated with progressive disease in myelodysplastic syndromes. Leuk Res 2012; 37:312-9. [PMID: 23153525 DOI: 10.1016/j.leukres.2012.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 10/19/2012] [Accepted: 10/20/2012] [Indexed: 11/30/2022]
Abstract
We have previously demonstrated that two prognostic features of myelodysplastic syndromes (MDS) and acute myelogenous leukemia (AML), mutant NRAS and over-expressing BCL-2, cooperate physically and functionally in vivo. Screening of MDS patient bone marrow (BM) identified NRAS:BCL-2 co-localization in 64% cases, correlating with percentage BM blasts, apoptotic features and disease status (p<0.0001). Localization of the complex at the plasma membrane or the mitochondria correlated with disease and apoptosis features in MDS patients, whilst caspase-9 mediated mechanism was elucidated in vivo and in vitro. The intensity and localization of the RAS:BCL-2 complex merits further evaluation as a novel biomarker of MDS.
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Abstract
Ras genes are frequently activated in cancer. Attempts to develop drugs that target mutant Ras proteins have, so far, been unsuccessful. Tumors bearing these mutations, therefore, remain among the most difficult to treat. Most efforts to block activated Ras have focused on pathways downstream. Drugs that inhibit Raf kinase have shown clinical benefit in the treatment of malignant melanoma. However, these drugs have failed to show clinical benefit in Ras mutant tumors. It remains unclear to what extent Ras depends on Raf kinase for transforming activity, even though Raf proteins bind directly to Ras and are certainly major effectors of Ras action in normal cells and in development. Furthermore, Raf kinase inhibitors can lead to paradoxical activation of the MAPK pathway. MEK inhibitors block the Ras-MAPK pathway, but often activate the PI3'-kinase, and have shown little clinical benefit as single agents. This activation is mediated by EGF-R and other receptor tyrosine kinases through relief of a negative feedback loop from ERK. Drug combinations that target multiple points within the Ras signaling network are likely to be necessary to achieve substantial clinical benefit. Other effectors may also contribute to Ras signaling and provide a source of targets. In addition, unbiased screens for genes necessary for Ras transformation have revealed new potential targets and have added to our understanding of Ras cancer biology.
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Affiliation(s)
- Stephan Gysin
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
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9
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Ferro E, Trabalzini L. RalGDS family members couple Ras to Ral signalling and that's not all. Cell Signal 2010; 22:1804-10. [PMID: 20478380 DOI: 10.1016/j.cellsig.2010.05.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 05/07/2010] [Indexed: 11/26/2022]
Abstract
Ras proteins function as molecular switches that are activated in response to signalling pathways initiated by various extracellular stimuli and subsequently bind to numerous effector proteins leading to the activation of several signalling cascades within the cell. Ras and Ras-related proteins belong to a large superfamily of small GTPases characterized by significant sequence and function similarities. Several evidence indicate the existence of complex signalling networks that link Ras with its relatives in the family. A key role in this cross-talk is played by guanine nucleotide exchange factors (GEFs) that serve both as regulators and as effectors of Ras family proteins. The members of the RalGDS family, RalGDS, RGL, RGL2/Rlf and RGL3, can interact with activated Ras through their Ras Binding Domain (RBD), but may function as effectors for other Ras family members. They possess a REM-CDC25 homology region like RasGEFs, but specifically activate only RalA and RalB and not Ras or other Ras-related small GTPases. In this review we provide an update on this recently discovered family of GEFs, highlighting their crucial role in coupling activated Ras to activation of Ral, thus regulating several fundamental cell processes, and also discussing some evidence supporting Ras-independent additional functions of RalGDS proteins.
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Affiliation(s)
- Elisa Ferro
- Dipartimento di Biologia Molecolare, Università degli Studi di Siena, Via Fiorentina, 1, 53100 Siena, Italy
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Lalli G. RalA and the exocyst complex influence neuronal polarity through PAR-3 and aPKC. J Cell Sci 2009; 122:1499-506. [PMID: 19383721 DOI: 10.1242/jcs.044339] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neuronal polarization requires localized cytoskeletal changes and polarized membrane traffic. Here, I report that the small GTPase RalA, previously shown to control neurite branching, also regulates neuronal polarity. RalA depletion, or ectopic expression of constitutively active RalA in cultured neurons inhibit axon formation. However, expression of a constitutively active RalA mutant that is unable to interact with the exocyst complex has no effect on neuronal polarization. Furthermore, depletion of the Sec6, Sec8 or Exo84 subunits of the exocyst complex also leads to unpolarized neurons. Early stages of neuronal polarization are accompanied by increasing levels of interaction of the exocyst complex with PAR-3 and atypical protein kinase C (aPKC), and by the RalA-dependent association of the exocyst complex with PAR-3. Thus, neuronal polarization involves a RalA-regulated association between mediators of vesicle trafficking (exocyst complex) and cell polarity (PAR-3).
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Affiliation(s)
- Giovanna Lalli
- The Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, UK.
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Makwana M, Serchov T, Hristova M, Bohatschek M, Gschwendtner A, Kalla R, Liu Z, Heumann R, Raivich G. Regulation and function of neuronal GTP-Ras in facial motor nerve regeneration. J Neurochem 2009; 108:1453-63. [PMID: 19284475 DOI: 10.1111/j.1471-4159.2009.05890.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Activation of Ras into the GTP-binding, 'ON' state is a key switch in the neurotrophin-mediated neuronal survival and neurite outgrowth, in vitro as well as in vivo. In the current study we explored changes in GTP-Ras levels following facial nerve injury and the ensuing regeneration and the effects of perturbing these changes in vivo using synapsin-promoter mediated neuronal expression of constitutively active Val12H-Ras (synRas). Quantification of GTP-Ras and total Ras revealed a precipitous drop in the relative GTP-Ras levels in the axotomized facial motor nucleus, to 40% of normal levels at 2 days after cut, followed by a partial recovery to 50-65% at 4-28 days. On western blots, control and axotomized nuclei from synRas mutants showed a 2.2- and 2.5-fold elevation in GTP-Ras, respectively, compared with their wild type littermate controls (p < 5%, anova, TUKEY post-hoc), with the levels in the axotomized synRas nucleus slightly but not significantly above that in the uninjured littermate control (p = 9.9%). Similar increase was also observed in the pERK but not pAKT targets of the Ras cascade. This moderate elevation of GTP-Ras strongly curtailed post-traumatic neuronal cell death (-65%), the influx of T-cells (-48%) as well as other parameters of neuroinflammatory response. Although synRas did not affect the speed of axonal regeneration or functional recovery it caused a very pronounced increase in central axonal sprouting. These current data emphasize the role of reduced active Ras, and by extension, the reduced overall level of retrograde neurotrophin signalling after axotomy, in mediating post-traumatic cell death and inflammation and in restricting the sprouting response. Moreover, the neuroprotective and central sprouting-enhancing effects of neuronal Val12H-Ras could help promote recovery in CNS injury.
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Affiliation(s)
- Milan Makwana
- Perinatal Brain Repair Group, Department of Obstetrics & Gynaecology, EGA Institute of Women's Health, University College London, London, UK
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Hoxa6 potentiates short-term hemopoietic cell proliferation and extended self-renewal. Exp Hematol 2009; 37:322-33.e3. [DOI: 10.1016/j.exphem.2008.10.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/10/2008] [Accepted: 10/28/2008] [Indexed: 11/23/2022]
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Abstract
The use of fluorescent probes is one of the most powerful techniques for gaining spatial and temporal knowledge of dynamic events within living cells. Localized increases in the signal from cytosolic fluorescent protein constructs, for example, are frequently used as evidence for translocation of proteins to specific sites within the cell. However, differences in optical and geometrical properties of cytoplasm can influence the recorded intensity of the probe signal. Pseudopodia are especially problematic because their cytoplasmic properties can cause abrupt increases in fluorescent signal of both GFP and fluorescein. Investigators should therefore be cautious when interpreting fluorescence changes within a cell, as these can result from either translocation of the probe or changes in the optical properties of the milieu surrounding the probe.
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Affiliation(s)
- Sharon Dewitt
- Neutrophil Signalling Group and Department of Haematology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, Wales, UK
| | - Richard L. Darley
- Neutrophil Signalling Group and Department of Haematology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, Wales, UK
| | - Maurice B. Hallett
- Neutrophil Signalling Group and Department of Haematology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, Wales, UK
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Activated Kras, but not Hras or Nras, may initiate tumors of endodermal origin via stem cell expansion. Mol Cell Biol 2008; 28:2659-74. [PMID: 18268007 DOI: 10.1128/mcb.01661-07] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The three closely related human Ras genes, Hras, Nras, and Kras, are all widely expressed, engage a common set of downstream effectors, and can each exhibit oncogenic activity. However, the vast majority of activating Ras mutations in human tumors involve Kras. Moreover, Kras mutations are most frequently seen in tumors of endodermally derived tissues (lung, pancreas, and colon), suggesting that activated Kras may affect an endodermal progenitor to initiate oncogenesis. Using a culture model of retinoic acid (RA)-induced stem cell differentiation to endoderm, we determined that while activated HrasV12 promotes differentiation and growth arrest in these endodermal progenitors, KrasV12 promotes their proliferation. Furthermore, KrasV12-expressing endodermal progenitors fail to differentiate upon RA treatment and continue to proliferate and maintain stem cell characteristics. NrasV12 neither promotes nor prevents differentiation. A structure-function analysis demonstrated that these distinct effects of the Ras isoforms involve their variable C-terminal domains, implicating compartmentalized signaling, and revealed a requirement for several established Ras effectors. These findings indicate that activated Ras isoforms exert profoundly different effects on endodermal progenitors and that mutant Kras may initiate tumorigenesis by expanding a susceptible stem/progenitor cell population. These results potentially explain the high frequency of Kras mutations in tumors of endodermal origin.
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Omidvar N, Kogan S, Beurlet S, le Pogam C, Janin A, West R, Noguera ME, Reboul M, Soulie A, Leboeuf C, Setterblad N, Felsher D, Lagasse E, Mohamedali A, Thomas NSB, Fenaux P, Fontenay M, Pla M, Mufti GJ, Weissman I, Chomienne C, Padua RA. BCL-2 and mutant NRAS interact physically and functionally in a mouse model of progressive myelodysplasia. Cancer Res 2008; 67:11657-67. [PMID: 18089795 DOI: 10.1158/0008-5472.can-07-0196] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Myelodysplastic syndromes (MDS) are clonal stem cell hematologic disorders that evolve to acute myeloid leukemia (AML) and thus model multistep leukemogenesis. Activating RAS mutations and overexpression of BCL-2 are prognostic features of MDS/AML transformation. Using NRASD12 and BCL-2, we created two distinct models of MDS and AML, where human (h)BCL-2 is conditionally or constitutively expressed. Our novel transplantable in vivo models show that expression of hBCL-2 in a primitive compartment by mouse mammary tumor virus-long terminal repeat results in a disease resembling human MDS, whereas the myeloid MRP8 promoter induces a disease with characteristics of human AML. Expanded leukemic stem cell (Lin(-)/Sca-1(+)/c-Kit(+)) populations and hBCL-2 in the increased RAS-GTP complex within the expanded Sca-1(+) compartment are described in both MDS/AML-like diseases. Furthermore, the oncogenic compartmentalizations provide the proapoptotic versus antiapoptotic mechanisms, by activating extracellular signal-regulated kinase and AKT signaling, in determination of the neoplastic phenotype. When hBCL-2 is switched off with doxycycline in the MDS mice, partial reversal of the phenotype was observed with persistence of bone marrow blasts and tissue infiltration as RAS recruits endogenous mouse (m)BCL-2 to remain active, thus demonstrating the role of the complex in the disease. This represents the first in vivo progression model of MDS/AML dependent on the formation of a BCL-2:RAS-GTP complex. The colocalization of BCL-2 and RAS in the bone marrow of MDS/AML patients offers targeting either oncogene as a therapeutic strategy.
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Affiliation(s)
- Nader Omidvar
- Institut National de la Sante et de la Recherche Medicale U718 and 728, Université Paris 7 Denis Diderot, Faculté de Médicine, Institut Universitaire d'Hématologie-IFR105, Paris, France
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16
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Rassool FV, Gaymes TJ, Omidvar N, Brady N, Beurlet S, Pla M, Reboul M, Lea N, Chomienne C, Thomas NSB, Mufti GJ, Padua RA. Reactive oxygen species, DNA damage, and error-prone repair: a model for genomic instability with progression in myeloid leukemia? Cancer Res 2007; 67:8762-71. [PMID: 17875717 DOI: 10.1158/0008-5472.can-06-4807] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Myelodysplastic syndromes (MDS) comprise a heterogeneous group of disorders characterized by ineffective hematopoiesis, with an increased propensity to develop acute myelogenous leukemia (AML). The molecular basis for MDS progression is unknown, but a key element in MDS disease progression is loss of chromosomal material (genomic instability). Using our two-step mouse model for myeloid leukemic disease progression involving overexpression of human mutant NRAS and BCL2 genes, we show that there is a stepwise increase in the frequency of DNA damage leading to an increased frequency of error-prone repair of double-strand breaks (DSB) by nonhomologous end-joining. There is a concomitant increase in reactive oxygen species (ROS) in these transgenic mice with disease progression. Importantly, RAC1, an essential component of the ROS-producing NADPH oxidase, is downstream of RAS, and we show that ROS production in NRAS/BCL2 mice is in part dependent on RAC1 activity. DNA damage and error-prone repair can be decreased or reversed in vivo by N-acetyl cysteine antioxidant treatment. Our data link gene abnormalities to constitutive DNA damage and increased DSB repair errors in vivo and provide a mechanism for an increase in the error rate of DNA repair with MDS disease progression. These data suggest treatment strategies that target RAS/RAC pathways and ROS production in human MDS/AML.
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Affiliation(s)
- Feyruz V Rassool
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201-1509, USA.
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Gaymes TJ, Padua RA, Pla M, Orr S, Omidvar N, Chomienne C, Mufti GJ, Rassool FV. Histone deacetylase inhibitors (HDI) cause DNA damage in leukemia cells: a mechanism for leukemia-specific HDI-dependent apoptosis? Mol Cancer Res 2006; 4:563-73. [PMID: 16877702 DOI: 10.1158/1541-7786.mcr-06-0111] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Histone deacetylase inhibitors (HDI) increase gene expression through induction of histone acetylation. However, it remains unclear whether increases in specific gene expression events determine the apoptotic response following HDI administration. Herein, we show that a variety of HDI trigger in hematopoietic cells not only widespread histone acetylation and DNA damage responses but also actual DNA damage, which is significantly increased in leukemic cells compared with normal cells. Thus, increase in H2AX and ataxia telangiectasia mutated (ATM) phosphorylation, early markers of DNA damage, occurs rapidly following HDI administration. Activation of the DNA damage and repair response following HDI treatment is further emphasized by localizing DNA repair proteins to regions of DNA damage. These events are followed by subsequent apoptosis of neoplastic cells but not normal cells. Our data indicate that induction of apoptosis by HDI may result predominantly through accumulation of excessive DNA damage in leukemia cells, leading to activation of apoptosis.
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Affiliation(s)
- Terry J Gaymes
- Department of Haematological Medicine, Leukemia Sciences Laboratories, The Rayne Institute, GKT School of Medicine, Denmark Hill campus, London, United Kingdom
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