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Karkache IY, Damodaran JR, Molstad DHH, Bradley EW. Serine/threonine phosphatases in osteoclastogenesis and bone resorption. Gene 2020; 771:145362. [PMID: 33338510 DOI: 10.1016/j.gene.2020.145362] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 11/24/2020] [Accepted: 12/08/2020] [Indexed: 12/27/2022]
Abstract
Maintenance of optimal bone mass is controlled through the concerted functions of several cell types, including bone resorbing osteoclasts. Osteoclasts function to remove calcified tissue during developmental bone modeling, and degrade bone at sites of damage during bone remodeling. Changes to bone homeostasis can arise with alterations in osteoclastogenesis and/or catabolic activity that are not offset by anabolic activity; thus, factors that regulate osteoclastogenesis and bone resorption are of interest to further our understanding of basic bone biology, and as potential targets for therapeutic intervention. Several key cytokines, including RANKL and M-CSF, as well as co-stimulatory factors elicit kinase signaling cascades that promote osteoclastogenesis. These kinase cascades are offset by the action of protein phosphatases, including members of the serine/threonine phosphatase family. Here we review the functions of serine/threonine phosphatases and their control of osteoclast differentiation and function, while highlighting deficiencies in our understanding of this understudied class of proteins within the field.
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Affiliation(s)
- Ismael Y Karkache
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States
| | - Jeyaram R Damodaran
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States
| | - David H H Molstad
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States
| | - Elizabeth W Bradley
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States; Stem Cell Institute, University of Minnesota, Minneapolis, MN 55455, United States.
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Innate immunity orchestrates the mobilization and homing of hematopoietic stem/progenitor cells by engaging purinergic signaling-an update. Purinergic Signal 2020; 16:153-166. [PMID: 32415576 DOI: 10.1007/s11302-020-09698-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/30/2020] [Indexed: 02/07/2023] Open
Abstract
Bone marrow (BM) as an active hematopoietic organ is highly sensitive to changes in body microenvironments and responds to external physical stimuli from the surrounding environment. In particular, BM tissue responds to several cues related to infections, strenuous exercise, tissue/organ damage, circadian rhythms, and physical challenges such as irradiation. These multiple stimuli affect BM cells to a large degree through a coordinated response of the innate immunity network as an important guardian for maintaining homeostasis of the body. In this review, we will foc++us on the role of purinergic signaling and innate immunity in the trafficking of hematopoietic stem/progenitor cells (HSPCs) during their egression from the BM into peripheral blood (PB), as seen along pharmacological mobilization, and in the process of homing and subsequent engraftment into BM after hematopoietic transplantation. Innate immunity mediates these processes by engaging, in addition to certain peptide-based factors, other important non-peptide mediators, including bioactive phosphosphingolipids and extracellular nucleotides, as the main topic of this review. Elucidation of these mechanisms will allow development of more efficient stem cell mobilization protocols to harvest the required number of HSPCs for transplantation and to accelerate hematopoietic reconstitution in transplanted patients.
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Wang Y, Xia Y, Kuang D, Duan Y, Wang G. PP2A regulates SCF-induced cardiac stem cell migration through interaction with p38 MAPK. Life Sci 2017; 191:59-67. [DOI: 10.1016/j.lfs.2017.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/22/2017] [Accepted: 10/02/2017] [Indexed: 12/29/2022]
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Janssens V, Zwaenepoel K, Rossé C, Petit MMR, Goris J, Parker PJ. PP2A binds to the LIM domains of lipoma-preferred partner through its PR130/B″ subunit to regulate cell adhesion and migration. J Cell Sci 2016; 129:1605-18. [PMID: 26945059 PMCID: PMC5333791 DOI: 10.1242/jcs.175778] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 02/18/2016] [Indexed: 01/23/2023] Open
Abstract
Here, we identify the LIM protein lipoma-preferred partner (LPP) as a binding partner of a specific protein phosphatase 2A (PP2A) heterotrimer that is characterised by the regulatory PR130/B″α1 subunit (encoded by PPP2R3A). The PR130 subunit interacts with the LIM domains of LPP through a conserved Zn²⁺-finger-like motif in the differentially spliced N-terminus of PR130. Isolated LPP-associated PP2A complexes are catalytically active. PR130 colocalises with LPP at multiple locations within cells, including focal contacts, but is specifically excluded from mature focal adhesions, where LPP is still present. An LPP-PR130 fusion protein only localises to focal adhesions upon deletion of the domain of PR130 that binds to the PP2A catalytic subunit (PP2A/C), suggesting that PR130-LPP complex formation is dynamic and that permanent recruitment of PP2A activity might be unfavourable for focal adhesion maturation. Accordingly, siRNA-mediated knockdown of PR130 increases adhesion of HT1080 fibrosarcoma cells onto collagen I and decreases their migration in scratch wound and Transwell assays. Complex formation with LPP is mandatory for these PR130-PP2A functions, as neither phenotype can be rescued by re-expression of a PR130 mutant that no longer binds to LPP. Our data highlight the importance of specific, locally recruited PP2A complexes in cell adhesion and migration dynamics.
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Affiliation(s)
- Veerle Janssens
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Karen Zwaenepoel
- Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Carine Rossé
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Research Centre, Institut Curie, Paris 75005, France
| | - Marleen M R Petit
- Molecular Oncology Laboratory, Dept. of Human Genetics, KU Leuven, Herestraat 49 PO-box 602, Leuven B-3000, Belgium
| | - Jozef Goris
- Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Peter J Parker
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Division of Cancer Studies King's College London, Guy's Hospital Campus, Thomas Street, London SE1 9RT, UK
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Human phosphatase CDC14A is recruited to the cell leading edge to regulate cell migration and adhesion. Proc Natl Acad Sci U S A 2016; 113:990-5. [PMID: 26747605 DOI: 10.1073/pnas.1515605113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cell adhesion and migration are highly dynamic biological processes that play important roles in organ development and cancer metastasis. Their tight regulation by small GTPases and protein phosphorylation make interrogation of these key processes of great importance. We now show that the conserved dual-specificity phosphatase human cell-division cycle 14A (hCDC14A) associates with the actin cytoskeleton of human cells. To understand hCDC14A function at this location, we manipulated native loci to ablate hCDC14A phosphatase activity (hCDC14A(PD)) in untransformed hTERT-RPE1 and colorectal cancer (HCT116) cell lines and expressed the phosphatase in HeLa FRT T-Rex cells. Ectopic expression of hCDC14A induced stress fiber formation, whereas stress fibers were diminished in hCDC14A(PD) cells. hCDC14A(PD) cells displayed faster cell migration and less adhesion than wild-type controls. hCDC14A colocalized with the hCDC14A substrate kidney- and brain-expressed protein (KIBRA) at the cell leading edge and overexpression of KIBRA was able to reverse the phenotypes of hCDC14A(PD) cells. Finally, we show that ablation of hCDC14A activity increased the aggressive nature of cells in an in vitro tumor formation assay. Consistently, hCDC14A is down-regulated in many tumor tissues and reduced hCDC14A expression is correlated with poorer survival of patients with cancer, to suggest that hCDC14A may directly contribute to the metastatic potential of tumors. Thus, we have uncovered an unanticipated role for hCDC14A in cell migration and adhesion that is clearly distinct from the mitotic and cytokinesis functions of Cdc14/Flp1 in budding and fission yeast.
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Chen W, Wang S, Xia J, Huang Z, Tu X, Shen Z. Protein phosphatase 2A plays an important role in migration of bone marrow stroma cells. Mol Cell Biochem 2015; 412:173-80. [PMID: 26708215 DOI: 10.1007/s11010-015-2624-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/08/2015] [Indexed: 01/07/2023]
Abstract
Administration of bone marrow stroma cells (BMSCs) has the potential to ameliorate degenerative disorders and to repair injured sites. The homing of transplanted BMSCs to damaged tissues is a critical property of engraftment. Therefore, it is important to understand signal molecules controlling migration of BMSCs. Here, we demonstrate that serine-threonine protein phosphatase 2A (PP2A) is responsive to migration of BMSCs. Pharmacological Inhibition of PP2A, using okadaic acid (OA), leads to attenuated cell migration in rat primary BMSCs both in the absence or presence of stromal cell-derived factor-1 (SDF-1). Consistent with the above findings, knockdown of the main catalytic subunit PP2Acα using small interfering RNA also attenuates chemotaxis of BMSCs. On the other hand, cell viability of BMSCs remains unchanged with OA treatment or knockdown of PP2Acα subunit. Moreover, we observed an upregulation of PP2A-B55β in transcription level after SDF-1 treatment, indicating their potential role as the functioning regulatory subunit of PP2A phosphatase in BMSCs migration model. Collectively, these data provide first insight into the modulation of BMSCs migration by PP2A phosphatase activity and lay a foundation for exploring PP2A signaling as a modulating target for BMSCs transplantation.
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Affiliation(s)
- Weiqian Chen
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou, 215006, Jiangsu, China
| | - Shizhen Wang
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou, 215006, Jiangsu, China
| | - Jun Xia
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou, 215006, Jiangsu, China
| | - Zan Huang
- Jiangsu Province Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, 210095, Jiangsu, China
| | - Xin Tu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing, 210061, Jiangsu, China
| | - Zhenya Shen
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou, 215006, Jiangsu, China.
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Nagareddy PR, Asfour A, Klyachkin YM, Abdel-Latif A. A novel role for bioactive lipids in stem cell mobilization during cardiac ischemia: new paradigms in thrombosis: novel mediators and biomarkers. J Thromb Thrombolysis 2014; 37:24-31. [PMID: 24318213 DOI: 10.1007/s11239-013-1032-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite major advances in pharmacological and reperfusion therapies, regenerating and/or replacing the infarcted myocardial tissue is an enormous challenge and therefore ischemic heart disease (IHD) remains a major cause of mortality and morbidity worldwide. Adult bone marrow is home for a variety of hematopoietic and non-hematopoietic stem cells including a small subset of primitive cells that carry a promising regenerative potential. It is now well established that myocardial ischemia (MI) induces mobilization of bone marrow-derived cells including differentiated lineage as well as undifferentiated stem cells. While the numbers of stem cells carrying pluripotent features among the mobilized stem cells is small, their regenerative capacity appears immense. Therapies aimed at selective mobilization of these pluripotent stem cells during myocardial ischemia have a promising potential to regenerate the injured myocardium. Emerging evidence suggest that bioactive sphingolipids such as sphingosine-1-phosphate and ceramide-1-phosphate hold a great promise in selective mobilization of pluripotent stem cells to the infarcted region during MI. This review highlights the recent advances in the mechanisms of stem cell mobilization and provides newer evidence in support of bioactive lipids as potential therapeutic agents in the treatment of ischemic heart disease.
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The role of bioactive lipids in stem cell mobilization and homing: novel therapeutics for myocardial ischemia. BIOMED RESEARCH INTERNATIONAL 2014; 2014:653543. [PMID: 24672794 PMCID: PMC3930186 DOI: 10.1155/2014/653543] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/13/2013] [Accepted: 10/11/2013] [Indexed: 11/25/2022]
Abstract
Despite significant advances in medical therapy and interventional strategies, the prognosis of millions of patients with acute myocardial infarction (AMI) and ischemic heart disease (IHD) remains poor. Currently, short of heart transplantation with all of its inherit limitations, there are no available treatment strategies that replace the infarcted myocardium. It is now well established that cardiomyocytes undergo continuous renewal, with contribution from bone marrow (BM)-derived stem/progenitor cells (SPCs). This phenomenon is upregulated during AMI by initiating multiple innate reparatory mechanisms through which BMSPCs are mobilized towards the ischemic myocardium and contribute to myocardial regeneration. While a role for the SDF-1/CXCR4 axis in retention of BMSPCs in bone marrow is undisputed, its exclusive role in their mobilization and homing to a highly proteolytic microenvironment, such as the ischemic/infarcted myocardium, is currently being challenged. Recent evidence suggests a pivotal role for bioactive lipids in the mobilization of BMSPCs at the early stages following AMI and their homing towards ischemic myocardium. This review highlights the recent advances in our understanding of the mechanisms of stem cell mobilization, provides newer evidence implicating bioactive lipids in BMSPC mobilization and differentiation, and discusses their potential as therapeutic agents in the treatment of IHD.
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Tesio M, Oser GM, Baccelli I, Blanco-Bose W, Wu H, Göthert JR, Kogan SC, Trumpp A. Pten loss in the bone marrow leads to G-CSF-mediated HSC mobilization. ACTA ACUST UNITED AC 2013; 210:2337-49. [PMID: 24127490 PMCID: PMC3804947 DOI: 10.1084/jem.20122768] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Loss of the phosphatase and tumor suppressor gene PTEN induces G-CSF production in myeloid and stromal cells, thereby promoting HSCs mobilization from the bone marrow to the spleen and the initiation of lethal leukemia. The phosphatase and tumor suppressor PTEN inhibits the phosphoinositol-3-kinase (PI3K) signaling pathway and plays a key role in cell growth, proliferation, survival, and migration. Pten conditional deletion using MxCre or Scl-CreERT leads to splenomegaly and leukemia formation, which occurs after the relocation of normal hematopoietic stem cells (HSCs) from the bone marrow to the spleen. Unexpectedly, dormant HSCs in the bone marrow do not enter the cell cycle upon Pten loss, they do not lose self-renewal activity, and they are not exhausted. Instead, Pten deficiency causes an up-regulation of the PI3K pathway in myeloid cells, but not in HSCs. Strikingly, myeloid cells secrete high levels of G-CSF upon Pten loss, leading to the mobilization of HSCs from the bone marrow and accumulation in the spleen. After deletion of Pten in mice lacking G-CSF, the splenomegaly, myeloproliferative disease, and splenic HSC accumulation are rescued. Our data show that although PTEN has little if any role in normal HSCs, it is essential to prevent overt G-CSF production by myeloid and stromal cells which otherwise causes HSCs to relocate to the spleen followed by lethal leukemia initiation.
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Affiliation(s)
- Melania Tesio
- Deutsches Krebsforschungszentrum (DKFZ), D-69120 Heidelberg, Germany
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Lam BD, Anthony EC, Hordijk PL. Cytoplasmic targeting of the proto-oncogene SET promotes cell spreading and migration. FEBS Lett 2012. [PMID: 23195690 DOI: 10.1016/j.febslet.2012.11.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The RhoGTPase Rac1 is activated in a polarised fashion and controls cell motility. We previously showed that Rac1 binds the PP2A inhibitor SET and recruits nuclear SET to the cytosol. We show that a SET mutant, lacking a nuclear localization signal, SET(ΔNLS), promotes cell spreading and motility. This was accompanied by an increase in the number and frequency of membrane ruffles. Pharmacological inhibition of PP2A did not mimic the effects of SET(ΔNLS), however, we found that expression of SET and SET(ΔNLS) increases the levels of the MAP kinases ERK1 and ERK2.
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Affiliation(s)
- B Daniel Lam
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, The Netherlands
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Rankin SM. Chemokines and adult bone marrow stem cells. Immunol Lett 2012; 145:47-54. [PMID: 22698183 DOI: 10.1016/j.imlet.2012.04.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 04/13/2012] [Indexed: 12/15/2022]
Abstract
The adult bone contains a number of distinct populations of stem cells, including haematopoietic stem cells, mesenchymal stem cells, endothelial progenitor cells and fibrocytes. While haematopoietic stem cells are required to provide a lifelong supply of blood cells it is thought that the other populations of stem cells play a role in tissue regeneration and potentially disease. The chemokine CXCL12 is produced constitutively in the bone marrow and, acting via CXCR4, is critical in maintaining HSPCs in a quiescent state and retaining all subsets of stem and progenitor cells in the bone marrow environment. The cytokine G-CSF, used clinically to mobilize haematopoietic stem cells for bone marrow transplants, activates the sympathetic nervous system and bone marrow macrophages to reduce the expression of CXCL12 by bone marrow stromal cells, thereby promoting the exit of haematopoietic stem cells from the bone marrow. Understanding the molecular mechanisms underlying G-CSF stimulated mobilization has led to development of CXCR4 antagonists as fast acting mobilizing agents for haematopoietic stem cells. Evidence now suggests that CXCR4 antagonists can similarly mobilize distinct subsets of progenitor cells, namely the endothelial progenitor cells and mesenchymal stem cells, but this requires conditioning of the bone marrow with VEGF rather than G-CSF.
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Affiliation(s)
- Sara M Rankin
- Leukocyte Biology Section, NHLI Division, Faculty of Medicine, Imperial College London, UK.
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Sahin AO, Buitenhuis M. Molecular mechanisms underlying adhesion and migration of hematopoietic stem cells. Cell Adh Migr 2012; 6:39-48. [PMID: 22647939 DOI: 10.4161/cam.18975] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hematopoietic stem cell transplantation is the most powerful treatment modality for a large number of hematopoietic malignancies, including leukemia. Successful hematopoietic recovery after transplantation depends on homing of hematopoietic stem cells to the bone marrow and subsequent lodging of those cells in specific niches in the bone marrow. Migration of hematopoietic stem cells to the bone marrow is a highly regulated process that requires correct regulation of the expression and activity of various molecules including chemoattractants, selectins and integrins. This review will discuss recent studies that have extended our understanding of the molecular mechanisms underlying adhesion, migration and bone marrow homing of hematopoietic stem cells.
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Affiliation(s)
- Aysegul Ocal Sahin
- Department of Hematology and Erasmus MC Stem Cell Institute for Regenerative Medicine, Erasmus MC, Rotterdam, The Netherlands
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Hematopoietic stem cell development, niches, and signaling pathways. BONE MARROW RESEARCH 2012; 2012:270425. [PMID: 22900188 PMCID: PMC3413998 DOI: 10.1155/2012/270425] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 05/30/2012] [Accepted: 06/13/2012] [Indexed: 12/22/2022]
Abstract
Hematopoietic stem cells (HSCs) play a key role in hematopoietic system that functions mainly in homeostasis and immune response. HSCs transplantation has been applied for the treatment of several diseases. However, HSCs persist in the small quantity within the body, mostly in the quiescent state. Understanding the basic knowledge of HSCs is useful for stem cell biology research and therapeutic medicine development. Thus, this paper emphasizes on HSC origin, source, development, the niche, and signaling pathways which support HSC maintenance and balance between self-renewal and proliferation which will be useful for the advancement of HSC expansion and transplantation in the future.
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Liu XP, Zheng HY, Qu M, Zhang Y, Cao FY, Wang Q, Ke D, Liu GP, Wang JZ. Upregulation of astrocytes protein phosphatase-2A stimulates astrocytes migration via inhibiting p38 MAPK in tg2576 mice. Glia 2012; 60:1279-88. [PMID: 22729898 DOI: 10.1002/glia.22347] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/13/2012] [Indexed: 12/30/2022]
Abstract
One of the earliest neuropathological changes in Alzheimer disease (AD) is the accumulation of astrocytes at sites of β-amyloid (Aβ) deposits, but the cause of this cellular response is unclear. As the activity of protein phosphatase 2A (PP2A) is significantly decreased in the AD brains, we studied the role of PP2A in astrocytes migration. We observed unexpectedly that PP2A activity associated with glial fibrillary acidic protein, an astrocyte marker, was significantly upregulated in tg2576 mice, demonstrated by an increased enzyme activity, a decreased demethylation at leucine-309 (DM-PP2Ac), and a decreased phosphorylation at tyrosine-307 of PP2A (pY307-PP2Ac). Further studies by using in vitro wound-healing model and transwell assay demonstrated that upregulation of PP2A pharmacologically and genetically could stimulate astrocytes migration. Activation of PP2A promotes actin organization and inhibits p38 mitogen-activated protein kinases (p38 MAPK), while simultaneous activation of p38 MAPK partially abolishes the PP2A-induced astrocytes migration. Our data suggest that activation of astrocytes PP2A in tg2567 mice may stimulate the migration of astrocytes to the amyloid plaques by p38 MAPK inhibition, implying that PP2A deficits observed in AD may cause Aβ accumulation via hindering the astrocytes migration.
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Affiliation(s)
- Xiu-Ping Liu
- Pathophysiology Department, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, HuBei, People's Republic of China
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Marquez-Curtis LA, Turner AR, Sridharan S, Ratajczak MZ, Janowska-Wieczorek A. The ins and outs of hematopoietic stem cells: studies to improve transplantation outcomes. Stem Cell Rev Rep 2011; 7:590-607. [PMID: 21140298 DOI: 10.1007/s12015-010-9212-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Deciphering the mechanisms of hematopoietic stem/progenitor cell (HSPC) mobilization and homing is important for the development of strategies to enhance the efficacy of HSPC transplantation and achieve the full potential of HSPC-based cellular therapy. Investigation of these mechanisms has revealed interdependence among the various molecules, pathways and cellular components involved, and underscored the complex nature of these two processes. This review summarizes recent progress in identifying the specific factors implicated in HSPC mobilization and homing, with emphasis on our own work. Particularly, we will discuss our studies on stromal cell-derived factor-1 and its interaction with its receptor CXCR4, proteases (matrix metalloproteinases and carboxypeptidase M), complement proteins (C1q, C3a, C5a, membrane attack complex), sphingosine-1-phosphate, and pharmacologic agents such as the histone deacetylase inhibitor valproic acid and hyaluronic acid.
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Affiliation(s)
- Leah A Marquez-Curtis
- Research & Development, Canadian Blood Services, CBS Edmonton Centre, 8249-114 St. NW, Edmonton, T6G 2R8, Alberta, Canada
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The role of PI3K/protein kinase B (PKB/c-akt) in migration and homing of hematopoietic stem and progenitor cells. Curr Opin Hematol 2011; 18:226-30. [PMID: 21519240 DOI: 10.1097/moh.0b013e32834760e5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW Hematopoietic stem cell (HSC) transplantation is the most powerful treatment modality for a variety of hematological disorders. Successful hematopoietic recovery after transplantation depends on optimal homing of HSCs to the bone marrow and subsequent lodging in the HSC niche. The molecular mechanisms underlying bone marrow homing are, thus far, incompletely understood. This review focuses on recent studies that extended our understanding of how the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (PKB/c-akt) signaling module can regulate migration and homing of HSCs. RECENT FINDINGS In addition to regulation of HSC maintenance and lineage development, it has recently become apparent that the PI3K/PKB signaling module plays a critical role in regulation of migration and adhesion of hematopoietic stem and progenitor cells. Activation of this signaling pathway enhances firm adhesion, reduces migration and inhibits bone marrow homing, whereas inhibition of PKB conversely induces bone marrow homing. SUMMARY These findings clearly implicate the PI3K/PKB signaling module in playing a critical role in regulation of bone marrow homing, suggesting that pharmacological modulation of this signaling molecule prior to transplantation may provide a clinical means of improving engraftment levels and accelerating hematopoietic recovery.
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A novel perspective on stem cell homing and mobilization: review on bioactive lipids as potent chemoattractants and cationic peptides as underappreciated modulators of responsiveness to SDF-1 gradients. Leukemia 2011; 26:63-72. [PMID: 21886175 DOI: 10.1038/leu.2011.242] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hematopoietic stem progenitor cells (HSPCs) respond robustly to α-chemokine stromal-derived factor-1 (SDF-1) gradients, and blockage of CXCR4, a seven-transmembrane-spanning G(αI)-protein-coupled SDF-1 receptor, mobilizes HSPCs into peripheral blood. Although the SDF-1-CXCR4 axis has an unquestionably important role in the retention of HSPCs in bone marrow (BM), new evidence shows that, in addition to SDF-1, the migration of HSPCs is directed by gradients of the bioactive lipids sphingosine-1 phosphate and ceramide-1 phosphate. Furthermore, the SDF-1 gradient may be positively primed/modulated by cationic peptides (C3a anaphylatoxin and cathelicidin) and, as previously demonstrated, HSPCs respond robustly even to very low SDF-1 gradients in the presence of priming factors. In this review, we discuss the role of bioactive lipids in stem cell trafficking and the consequences of HSPC priming by cationic peptides. Together, these phenomena support a picture in which the SDF-1-CXCR4 axis modulates homing, BM retention and mobilization of HSPCs in a more complex way than previously envisioned.
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Shiozawa Y, Pienta KJ, Taichman RS. Hematopoietic stem cell niche is a potential therapeutic target for bone metastatic tumors. Clin Cancer Res 2011; 17:5553-8. [PMID: 21676926 DOI: 10.1158/1078-0432.ccr-10-2505] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite significant improvements in therapy, the prognosis for cancer with bone metastasis is generally poor. Therefore, there is a great need for new therapeutic approaches for metastatic disease. It has been appreciated that tumor cells metastasize to bone using mechanisms similar to those of hematopoietic stem cells (HSC) homing to bone marrow (e.g., CXCL12/CXCR4). It was recently found that prostate cancer cells target the bone marrow microenvironment for HSCs, or the HSC niche, during metastasis. Of importance, these disseminated prostate cancer cells can be mobilized out of the niche with the use of HSC mobilizing agents. These findings suggest that the bone marrow HSC niche is a potential therapeutic target for metastatic disease. Therefore, a hypothesis worth considering is that agents that can disrupt the interactions between tumor cells and the HSC niche may be efficacious when used in conjunction with standard chemotherapeutic agents. Although further understanding of the tumor-niche interactions is needed, the concept of targeting the niche in conjunction with chemotherapy could open up new possibilities to eradicate incurable metastatic diseases.
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Affiliation(s)
- Yusuke Shiozawa
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
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Low expression of PP2A regulatory subunit B55α is associated with T308 phosphorylation of AKT and shorter complete remission duration in acute myeloid leukemia patients. Leukemia 2011; 25:1711-7. [PMID: 21660042 PMCID: PMC3191228 DOI: 10.1038/leu.2011.146] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The regulation of Protein Kinase B (AKT) is a dynamic process that depends on the balance between phosphorylation by upstream kinases for activation and inactivation by dephosphorylation by protein phosphatases. Phosphorylated AKT is commonly found in acute myeloid leukemia (AML) and confers an unfavorable prognosis. Understanding the relative importance of upstream kinases and AKT phosphatase in the activation of AKT is relevant for the therapeutic targeting of this signaling axis in AML. The B55α subunit of Protein Phosphatase 2A (PP2A) has been implicated in AKT dephosphorylation but its role in regulating AKT in AML is unknown. We examined B55α protein expression in blast cells derived from 511 AML patients using Reverse Phase Protein Analysis (RPPA). B55α protein expression was lower in AML cells compared to normal CD34+ cells. B55α protein levels negatively correlated with T308 phosphorylation levels. Low levels of B55α were associated with shorter complete remission duration demonstrating that decreased expression is an adverse prognostic factor in AML. These findings suggest that decreased B55α expression in AML is at least partially responsible for increased AKT signaling in AML and suggests that therapeutic targeting of PP2A could counteract this.
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de Boer HC, Hovens MM, van Oeveren-Rietdijk AM, Snoep JD, de Koning EJP, Tamsma JT, Huisman MV, Rabelink AJ, van Zonneveld AJ. Human CD34+/KDR+ cells are generated from circulating CD34+ cells after immobilization on activated platelets. Arterioscler Thromb Vasc Biol 2010; 31:408-15. [PMID: 21030714 DOI: 10.1161/atvbaha.110.216879] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE The presence of kinase-insert domain-containing receptor (KDR) on circulating CD34+ cells is assumed to be indicative for the potential of these cells to support vascular maintenance and repair. However, in bone marrow and in granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood, less than 0.5% of CD34+ cells co-express KDR. Therefore, we studied whether CD34+/KDR+ cells are generated in the peripheral circulation. METHODS AND RESULTS Using an ex vivo flow model, we show that activated platelets enable CD34+ cells to home to sites of vascular injury and that upon immobilization, KDR is translocated from an endosomal compartment to the cell-surface within 15 minutes. In patients with diabetes mellitus type 2, the percentage of circulating CD34+ co-expressing KDR was significantly elevated compared to age-matched controls. When treated with aspirin, the patients showed a 49% reduction in the generation of CD34+/KDR+ cells, indicating that the level of circulating CD34+/KDR+ cells also relates to in vivo platelet activation. CONCLUSIONS Circulating CD34+/KDR+ are not mobilized from bone marrow as a predestined endothelial progenitor cell population but are mostly generated from circulating multipotent CD34+ cells at sites of vascular injury. Therefore, the number of circulating CD34+/KDR+ cells may serve as a marker for vascular injury.
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Affiliation(s)
- H C de Boer
- Department of Nephrology, Leiden University Medical Center, Albinusdreef 2, Leiden, the Netherlands
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Protein kinase B (PKB/c-akt) regulates homing of hematopoietic progenitors through modulation of their adhesive and migratory properties. Blood 2010; 116:2373-84. [PMID: 20566894 DOI: 10.1182/blood-2009-10-250258] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Limited number of hematopoietic stem cells in umbilical cord blood (UCB) presents a problem when using UCB for stem cell transplantation. Improving their homing capacity could reduce the need for high initial cell numbers during transplantation procedures. Although it is evident that protein kinase B (PKB/c-Akt) plays an important role in regulation of migration of various cell types, a role for PKB in regulation of migration and homing of human hematopoietic stem and progenitor cells remains to be determined. PKB activity was found to be required for induction of adhesion to bone marrow-derived stromal cells and detrimental for migration of UCB-derived CD34(+) hematopoietic progenitors. In addition, PKB activity was found to positively regulate integrin expression. CD34(+) hematopoietic progenitors, and their capacity to form colonies in vitro, were not affected by transient inhibition of PKB. Finally, transplantation of β2-microglobulin(-/-) nonobese diabetic/severe combined immunodeficient mice with CD34(+) cells ectopically expressing constitutively active PKB resulted in reduced migration to the bone marrow, whereas inhibition of PKB activity resulted in an induction in bone marrow homing and engraftment. These results indicate that transient inhibition of PKB activity may provide a means for ex vivo stem cell manipulation to improve bone marrow transplantation regimes.
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Luttrell LM, Gesty-Palmer D. Beyond desensitization: physiological relevance of arrestin-dependent signaling. Pharmacol Rev 2010; 62:305-30. [PMID: 20427692 DOI: 10.1124/pr.109.002436] [Citation(s) in RCA: 321] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Heptahelical G protein-coupled receptors are the most diverse and therapeutically important family of receptors in the human genome. Ligand binding activates heterotrimeric G proteins that transmit intracellular signals by regulating effector enzymes or ion channels. G protein signaling is terminated, in large part, by arrestin binding, which uncouples the receptor and G protein and targets the receptor for internalization. It is clear, however, that heptahelical receptor signaling does not end with desensitization. Arrestins bind a host of catalytically active proteins and serve as ligand-regulated scaffolds that recruit protein and lipid kinase, phosphatase, phosphodiesterase, and ubiquitin ligase activity into the receptor-arrestin complex. Although many of these arrestin-bound effectors serve to modulate G protein signaling, degrading second messengers and regulating endocytosis and trafficking, other signals seem to extend beyond the receptor-arrestin complex to regulate such processes as protein translation and gene transcription. Although these findings have led to a re-envisioning of heptahelical receptor signaling, little is known about the physiological roles of arrestin-dependent signaling. In vivo, the duality of arrestin function makes it difficult to dissociate the consequences of arrestin-dependent desensitization from those that might be ascribed to arrestin-mediated signaling. Nonetheless, recent evidence generated using arrestin knockouts, G protein-uncoupled receptor mutants, and arrestin pathway-selective "biased agonists" is beginning to reveal that arrestin signaling plays important roles in the retina, central nervous system, cardiovascular system, bone remodeling, immune system, and cancer. Understanding the signaling roles of arrestins may foster the development of pathway-selective drugs that exploit these pathways for therapeutic benefit.
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Affiliation(s)
- Louis M Luttrell
- Department of Medicine, Medical University of South Carolina, USA
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Basu S, Broxmeyer HE. CCR5 ligands modulate CXCL12-induced chemotaxis, adhesion, and Akt phosphorylation of human cord blood CD34+ cells. THE JOURNAL OF IMMUNOLOGY 2009; 183:7478-88. [PMID: 19917679 DOI: 10.4049/jimmunol.0900542] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
CXCL12 and its receptor CXCR4 play an important role in hematopoietic stem/progenitor cell (HSPC) migration from and retention within the bone marrow. HSPCs are very selective in their chemotactic response and undergo chemotaxis only in response to CXCL12. In addition to CXCR4, HSPCs express receptors for various other chemokines; however, the role of these receptors is not well understood. Freshly isolated CD34(+) cells (highly enriched for HSPCs) from cord blood (CB) express low levels of CCR5; however, if the cells were washed with acidic buffer before Ab staining to remove any ligand bound to CCR5, then nearly 80% of CD34(+) CB cells were found to express CCR5 on the cell surface. Although none of the CCR5 ligands investigated in this study (CCL3, CCL4, and CCL5) induced chemotaxis, at relatively high concentrations they transiently enhanced CXCL12-mediated chemotaxis of CD34(+) CB cells. In contrast, CXCL12-mediated adhesion of cells to VCAM-1-coated surfaces was reduced if CD34(+) CB cells were pretreated with these CCR5 ligands for 15 min. The effect of these chemokines on CXCL12-mediated responses was not at the level of CXCR4 expression, but on downstream signaling pathways elicited by CXCL12. Pretreatment with CCR5 chemokines enhanced CXCL12-mediated Akt phosphorylation, but down-modulated calcium flux in CD34(+) CB cells. Modulation of CXCL12-mediated responses of CD34(+) cells by CCR5 chemokines provides a possible mechanism that underlies movement of HSPCs during inflammation.
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Affiliation(s)
- Sunanda Basu
- Department of Microbiology and Immunology and Walther Oncology Center, Indiana University School of Medicine, Research Institute No. 2 Building, Room 302, 950 West Walnut Street, Indianapolis, IN 46202, USA.
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Liu Y, Hangoc G, Campbell TB, Goodman M, Tao W, Pollok K, Srour EF, Broxmeyer HE. Identification of parameters required for efficient lentiviral vector transduction and engraftment of human cord blood CD34(+) NOD/SCID-repopulating cells. Exp Hematol 2008; 36:947-56. [PMID: 18640494 DOI: 10.1016/j.exphem.2008.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 06/11/2008] [Accepted: 06/12/2008] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Human cord blood (CB) is a potential source of hematopoietic stem cells (HSC) for gene therapy to treat patients with hematopoietic disorders. However, limited numbers of CB CD34(+) cells, low transduction efficiency with lentiviral vectors (LVs), and low engraftment efficiency of nonobese diabetic/severe combined immunodeficient (NOD/SCID) repopulating cells (SRC), a measure of HSC, are blocks to this procedure. To optimize culture and transduction conditions, we compared various lengths of time for prestimulation before transduction, transduction duration, and posttransduction cell culture. MATERIALS AND METHODS We used a LV to transduce human CB CD34(+) cells followed by engraftment into NOD/SCID mice. We evaluated the effects of prestimulation and transduction time and optimized ex vivo cell culture duration before transplantation. RESULTS We were able to achieve up to 40% transduction efficiency and up to 50% engraftment efficiency of SRC in CB CD34(+) cells when CB CD34(+) cells were either not prestimulated or prestimulated in 1% fetal bovine serum medium for 1 hour, followed by 5 hours transduction and 3 days culture in a cocktail of growth factors after transduction. No apparent functional changes of CB CD34(+) cells were noted under these conditions. CONCLUSION This gene-transduction/cell-expansion protocol is the first systematic study to optimize prestimulation time, transduction time, and, very importantly, ex vivo culture time after transduction, and may be of use for LV gene transduction in a gene therapy setting.
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Affiliation(s)
- Ying Liu
- Department of Microbiology and Immunology and the Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Wiles TJ, Dhakal BK, Eto DS, Mulvey MA. Inactivation of host Akt/protein kinase B signaling by bacterial pore-forming toxins. Mol Biol Cell 2008; 19:1427-38. [PMID: 18234841 PMCID: PMC2291440 DOI: 10.1091/mbc.e07-07-0638] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 11/01/2007] [Accepted: 01/23/2008] [Indexed: 01/13/2023] Open
Abstract
Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs), and they have the capacity to induce the death and exfoliation of target uroepithelial cells. This process can be facilitated by the pore-forming toxin alpha-hemolysin (HlyA), which is expressed and secreted by many UPEC isolates. Here, we demonstrate that HlyA can potently inhibit activation of Akt (protein kinase B), a key regulator of host cell survival, inflammatory responses, proliferation, and metabolism. HlyA ablates Akt activation via an extracellular calcium-dependent, potassium-independent process requiring HlyA insertion into the host plasma membrane and subsequent pore formation. Inhibitor studies indicate that Akt inactivation by HlyA involves aberrant stimulation of host protein phosphatases. We found that two other bacterial pore-forming toxins (aerolysin from Aeromonas species and alpha-toxin from Staphylococcus aureus) can also markedly attenuate Akt activation in a dose-dependent manner. These data suggest a novel mechanism by which sublytic concentrations of HlyA and other pore-forming toxins can modulate host cell survival and inflammatory pathways during the course of a bacterial infection.
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Affiliation(s)
- Travis J. Wiles
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
| | - Bijaya K. Dhakal
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
| | - Danelle S. Eto
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
| | - Matthew A. Mulvey
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
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