Abstract
Studies of pericytes have been retarded by the lack of appropriate markers for identification of these perivascular mural cells. Use of antibodies against the NG2 proteoglycan as a pericyte marker has greatly facilitated recent studies of pericytes, emphasizing the intimate spatial relationship between pericytes and endothelial cells, allowing more accurate quantification of pericyte/endothelial cell ratios in different vascular beds, and revealing the participation of pericytes throughout all stages of blood vessel formation. The functional importance of NG2 in pericyte biology has been established via NG2 knockdown (in vitro) and knockout (in vivo) strategies that reveal significant deficits in blood vessel formation when NG2 is absent from pericytes. NG2 influences pericyte proliferation and motility by acting as an auxiliary receptor that enhances signaling through integrins and receptor tyrosine kinase growth factor receptors. By acting in a trans orientation, NG2 also activates integrin signaling in closely apposed endothelial cells, leading to enhanced maturation and formation of endothelial cell junctions. NG2 null mice exhibit reduced growth of both mammary and brain tumors that can be traced to deficits in tumor vascularization. Use of Cre-Lox technology to produce pericyte-specific NG2 null mice has revealed specific deficits in tumor vessels that include decreased pericyte ensheathment of endothelial cells, diminished assembly of the vascular basement membrane, reduced vessel patency, and increased vessel leakiness. Interestingly, myeloid-specific NG2 null mice exhibit even larger deficits in tumor vascularization, leading to correspondingly slower tumor growth. Myeloid-specific NG2 null mice are deficient in their ability to recruit macrophages to tumors and other sites of inflammation. This absence of macrophages deprives pericytes of a signal that is crucial for their ability to interact with endothelial cells. The interplay between pericytes, endothelial cells, and macrophages promises to be an extremely fertile area of future study.
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References
Dejana E, Hirschi KK, Simons M (2017) The molecular basis of endothelial cell plasticity. Nat Commun 8:14361
Eelen G et al (2018) Endothelial cell metabolism. Physiol Rev 98(1):3–58
Franco CA, Gerhardt H (2017) Morph or move? How distinct endothelial cell responses to blood flow shape vascular networks. Dev Cell 41(6):574–576
Risau W (1997) Mechanisms of angiogenesis. Nature 386(6626):671–674
Watson EC, Grant ZL, Coultas L (2017) Endothelial cell apoptosis in angiogenesis and vessel regression. Cell Mol Life Sci 74(24):4387–4403
Armulik A, Abramsson A, Betsholtz C (2005) Endothelial/pericyte interactions. Circ Res 97(6):512–523
Gerhardt H, Betsholtz C (2003) Endothelial-pericyte interactions in angiogenesis. Cell Tissue Res 314(1):15–23
Davis GE, Senger DR (2005) Endothelial extracellular matrix: biosynthesis, remodeling, and functions during vascular morphogenesis and neovessel stabilization. Circ Res 97(11):1093–1107
Kalluri R (2003) Basement membranes: structure, assembly and role in tumour angiogenesis. Nat Rev Cancer 3(6):422–433
Wagenseil JE, Mecham RP (2009) Vascular extracellular matrix and arterial mechanics. Physiol Rev 89(3):957–989
You WK, Bonaldo P, Stallcup WB (2012) Collagen VI ablation retards brain tumor progression due to deficits in assembly of the vascular basal lamina. Am J Pathol 180(3):1145–1158
You WK, Stallcup WB (2015) Melanoma progression in the brain: role of pericytes, the basal lamina, and endothelial cells in tumor vascularization. In: Hayat MA (ed) Brain metastases from primary tumors, 1st edn. Academic, New York, pp 133–143
Allt G, Lawrenson JG (2001) Pericytes: cell biology and pathology. Cells Tissues Organs 169(1):1–11
Bergers G, Song S (2005) The role of pericytes in blood-vessel formation and maintenance. Neuro-Oncology 7(4):452–464
Betsholtz C, Lindblom P, Gerhardt H (2005) Role of pericytes in vascular morphogenesis. EXS 94:115–125
Sims DE (2000) Diversity within pericytes. Clin Exp Pharmacol Physiol 27(10):842–846
Thomas H, Cowin AJ, Mills SJ (2017) The importance of pericytes in healing: wounds and other pathologies. Int J Mol Sci 18(6):1129
Biname F (2014) Transduction of extracellular cues into cell polarity: the role of the transmembrane proteoglycan NG2. Mol Neurobiol 50(2):482–493
Sakry D, Trotter J (2016) The role of the NG2 proteoglycan in OPC and CNS network function. Brain Res 1638(Pt B):161–166
Stallcup WB (2002) The NG2 proteoglycan: past insights and future prospects. J Neurocytol 31(6–7):423–435
Stallcup WB, Huang FJ (2008) A role for the NG2 proteoglycan in glioma progression. Cell Adhes Migr 2(3):192–201
Grako KA, Stallcup WB (1995) Participation of the NG2 proteoglycan in rat aortic smooth muscle cell responses to platelet-derived growth factor. Exp Cell Res 221(1):231–240
Schrappe M et al (1991) Correlation of chondroitin sulfate proteoglycan expression on proliferating brain capillary endothelial cells with the malignant phenotype of astroglial cells. Cancer Res 51(18):4986–4993
Beck L Jr, D’Amore PA (1997) Vascular development: cellular and molecular regulation. FASEB J 11(5):365–373
Hirschi KK et al (1999) Endothelial cells modulate the proliferation of mural cell precursors via platelet-derived growth factor-BB and heterotypic cell contact. Circ Res 84(3):298–305
Orlidge A, D'Amore PA (1987) Inhibition of capillary endothelial cell growth by pericytes and smooth muscle cells. J Cell Biol 105(3):1455–1462
Sato Y, Rifkin DB (1989) Inhibition of endothelial cell movement by pericytes and smooth muscle cells: activation of a latent transforming growth factor-beta 1-like molecule by plasmin during co-culture. J Cell Biol 109(1):309–315
Nayak RC et al (1988) A monoclonal antibody (3G5)-defined ganglioside antigen is expressed on the cell surface of microvascular pericytes. J Exp Med 167(3):1003–1015
Schlingemann RO et al (1996) Aminopeptidase a is a constituent of activated pericytes in angiogenesis. J Pathol 179(4):436–442
Lindahl P, Betsholtz C (1998) Not all myofibroblasts are alike: revisiting the role of PDGF-A and PDGF-B using PDGF-targeted mice. Curr Opin Nephrol Hypertens 7(1):21–26
Lindahl P et al (1997) Pericyte loss and microaneurysm formation in PDGF-B-deficient mice. Science 277(5323):242–245
Song S et al (2005) PDGFRbeta+ perivascular progenitor cells in tumours regulate pericyte differentiation and vascular survival. Nat Cell Biol 7(9):870–9
Ozerdem U et al (2001) NG2 proteoglycan is expressed exclusively by mural cells during vascular morphogenesis. Dev Dyn 222(2):218–227
Ozerdem U, Monosov E, Stallcup WB (2002) NG2 proteoglycan expression by pericytes in pathological microvasculature. Microvasc Res 63(1):129–134
Ozerdem U, Stallcup WB (2003) Early contribution of pericytes to angiogenic sprouting and tube formation. Angiogenesis 6(3):241–249
Tigges U et al (2008) FGF2-dependent neovascularization of subcutaneous Matrigel plugs is initiated by bone marrow-derived pericytes and macrophages. Development 135(3):523–532
Virgintino D et al (2007) An intimate interplay between precocious, migrating pericytes and endothelial cells governs human fetal brain angiogenesis. Angiogenesis 10(1):35–45
Hellstrom M et al (1999) Role of PDGF-B and PDGFR-beta in recruitment of vascular smooth muscle cells and pericytes during embryonic blood vessel formation in the mouse. Development 126(14):3047–3055
Gibby K et al (2012) Early vascular deficits are correlated with delayed mammary tumorigenesis in the MMTV-PyMT transgenic mouse following genetic ablation of the neuron-glial antigen 2 proteoglycan. Breast Cancer Res 14(2):R67
Huang FJ et al (2010) Pericyte deficiencies lead to aberrant tumor vascularization in the brain of the NG2 null mouse. Dev Biol 344(2):1035–1046
You WK et al (2014) NG2 proteoglycan promotes tumor vascularization via integrin-dependent effects on pericyte function. Angiogenesis 17(1):61–76
Fukushi J et al (2003) Expression of NG2 proteoglycan during endochondral and intramembranous ossification. Dev Dyn 228(1):143–148
Kadoya K et al (2008) NG2 proteoglycan expression in mouse skin: altered postnatal skin development in the NG2 null mouse. J Histochem Cytochem 56(3):295–303
Kucharova K, Stallcup WB (2017) Distinct NG2 proteoglycan-dependent roles of resident microglia and bone marrow-derived macrophages during myelin damage and repair. PLoS One 12(11):e0187530
Nishiyama A et al (1996) Co-localization of NG2 proteoglycan and PDGF alpha-receptor on O2A progenitor cells in the developing rat brain. J Neurosci Res 43(3):299–314
Yotsumoto F et al (2015) NG2 proteoglycan-dependent recruitment of tumor macrophages promotes pericyte-endothelial cell interactions required for brain tumor vascularization. Oncoimmunology 4(4):e1001204
Kucharova K, Stallcup WB (2015) NG2-proteoglycan-dependent contributions of oligodendrocyte progenitors and myeloid cells to myelin damage and repair. J Neuroinflammation 12(1):161
Brachvogel B et al (2005) Perivascular cells expressing annexin A5 define a novel mesenchymal stem cell-like population with the capacity to differentiate into multiple mesenchymal lineages. Development 132(11):2657–2668
Caplan AI (2008) All MSCs are pericytes? Cell Stem Cell 3(3):229–230
Crisan M et al (2008) A perivascular origin for mesenchymal stem cells in multiple human organs. Cell Stem Cell 3(3):301–313
Traktuev DO et al (2008) A population of multipotent CD34-positive adipose stromal cells share pericyte and mesenchymal surface markers, reside in a periendothelial location, and stabilize endothelial networks. Circ Res 102(1):77–85
She ZG et al (2016) NG2 proteoglycan ablation reduces foam cell formation and atherogenesis via decreased low-density lipoprotein retention by synthetic smooth muscle cells. Arterioscler Thromb Vasc Biol 36(1):49–59
Tigges U, Komatsu M, Stallcup WB (2013) Adventitial pericyte progenitor/mesenchymal stem cells participate in the restenotic response to arterial injury. J Vasc Res 50(2):134–144
Murfee WL, Skalak TC, Peirce SM (2005) Differential arterial/venous expression of NG2 proteoglycan in perivascular cells along microvessels: identifying a venule-specific phenotype. Microcirculation 12(2):151–160
Murfee WL et al (2006) Perivascular cells along venules upregulate NG2 expression during microvascular remodeling. Microcirculation 13(3):261–273
Fang X et al (1999) Cytoskeletal reorganization induced by engagement of the NG2 proteoglycan leads to cell spreading and migration. Mol Biol Cell 10(10):3373–3387
Lin XH, Dahlin-Huppe K, Stallcup WB (1996) Interaction of the NG2 proteoglycan with the actin cytoskeleton. J Cell Biochem 63(4):463–477
Lin XH et al (1996) NG2 proteoglycan and the actin-binding protein fascin define separate populations of actin-containing filopodia and lamellipodia during cell spreading and migration. Mol Biol Cell 7(12):1977–1993
Majumdar M, Vuori K, Stallcup WB (2003) Engagement of the NG2 proteoglycan triggers cell spreading via rac and p130cas. Cell Signal 15(1):79–84
Couchman JR (2003) Syndecans: proteoglycan regulators of cell-surface microdomains? Nat Rev Mol Cell Biol 4(12):926–937
Cattaruzza S et al (2013) Multivalent proteoglycan modulation of FGF mitogenic responses in perivascular cells. Angiogenesis 16(2):309–327
Goretzki L et al (1999) High-affinity binding of basic fibroblast growth factor and platelet-derived growth factor-AA to the core protein of the NG2 proteoglycan. J Biol Chem 274(24):16831–16837
Rapraeger AC (1995) In the clutches of proteoglycans: how does heparan sulfate regulate FGF binding? Chem Biol 2(10):645–649
Grako KA et al (1999) PDGF (alpha)-receptor is unresponsive to PDGF-AA in aortic smooth muscle cells from the NG2 knockout mouse. J Cell Sci 112(Pt 6):905–915
Nishiyama A et al (1996) Interaction between NG2 proteoglycan and PDGF alpha-receptor on O2A progenitor cells is required for optimal response to PDGF. J Neurosci Res 43(3):315–330
Chekenya M et al (2008) The progenitor cell marker NG2/MPG promotes chemoresistance by activation of integrin-dependent PI3K/Akt signaling. Oncogene 27(39):5182–5194
Fukushi J, Makagiansar IT, Stallcup WB (2004) NG2 proteoglycan promotes endothelial cell motility and angiogenesis via engagement of galectin-3 and alpha3beta1 integrin. Mol Biol Cell 15(8):3580–3590
Stallcup WB (2017) NG2 proteoglycan enhances brain tumor progression by promoting beta-1 integrin activation in both cis and trans orientations. Cancers (Basel) 9(4) E31
Makagiansar IT et al (2004) Phosphorylation of NG2 proteoglycan by protein kinase C-alpha regulates polarized membrane distribution and cell motility. J Biol Chem 279(53):55262–55270
Makagiansar IT et al (2007) Differential phosphorylation of NG2 proteoglycan by ERK and PKCalpha helps balance cell proliferation and migration. J Cell Biol 178(1):155–165
Barritt DS et al (2000) The multi-PDZ domain protein MUPP1 is a cytoplasmic ligand for the membrane-spanning proteoglycan NG2. J Cell Biochem 79(2):213–224
Chatterjee N et al (2008) Interaction of syntenin-1 and the NG2 proteoglycan in migratory oligodendrocyte precursor cells. J Biol Chem 283(13):8310–8317
Stegmuller J et al (2003) The proteoglycan NG2 is complexed with alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors by the PDZ glutamate receptor interaction protein (GRIP) in glial progenitor cells. Implications for glial-neuronal signaling. J Biol Chem 278(6):3590–3598
Ozerdem U, Stallcup WB (2004) Pathological angiogenesis is reduced by targeting pericytes via the NG2 proteoglycan. Angiogenesis 7(3):269–276
Luque A et al (1996) Activated conformations of very late activation integrins detected by a group of antibodies (HUTS) specific for a novel regulatory region (355–425) of the common beta 1 chain. J Biol Chem 271(19):11067–11075
Tillet E et al (1997) The membrane-spanning proteoglycan NG2 binds to collagens V and VI through the central nonglobular domain of its core protein. J Biol Chem 272(16):10769–10776
Lenter M et al (1993) A monoclonal antibody against an activation epitope on mouse integrin chain beta 1 blocks adhesion of lymphocytes to the endothelial integrin alpha 6 beta 1. Proc Natl Acad Sci U S A 90(19):9051–9055
Lin EY et al (2003) Progression to malignancy in the polyoma middle T oncoprotein mouse breast cancer model provides a reliable model for human diseases. Am J Pathol 163(5):2113–2126
Maglione JE et al (2001) Transgenic Polyoma middle-T mice model premalignant mammary disease. Cancer Res 61(22):8298–8305
Fidler IJ (1973) Selection of successive tumour lines for metastasis. Nat New Biol 242(118):148–149
Bergers G, Benjamin LE (2003) Tumorigenesis and the angiogenic switch. Nat Rev Cancer 3(6):401–410
Hanahan D, Folkman J (1996) Patterns and emerging mechanisms of the angiogenic switch during tumorigenesis. Cell 86(3):353–364
Folkman J et al (1989) Induction of angiogenesis during the transition from hyperplasia to neoplasia. Nature 339(6219):58–61
Brekke C et al (2006) NG2 expression regulates vascular morphology and function in human brain tumours. NeuroImage 29(3):965–976
Maciag PC et al (2008) Cancer immunotherapy targeting the high molecular weight melanoma-associated antigen protein results in a broad antitumor response and reduction of pericytes in the tumor vasculature. Cancer Res 68(19):8066–8075
Wang J et al (2011) Targeting the NG2/CSPG4 proteoglycan retards tumour growth and angiogenesis in preclinical models of GBM and melanoma. PLoS One 6(7):e23062
Coffelt SB, Hughes R, Lewis CE (2009) Tumor-associated macrophages: effectors of angiogenesis and tumor progression. Biochim Biophys Acta 1796(1):11–18
De Palma M, Naldini L (2009) Tie2-expressing monocytes (TEMs): novel targets and vehicles of anticancer therapy? Biochim Biophys Acta 1796(1):5–10
Lin EY et al (2006) Macrophages regulate the angiogenic switch in a mouse model of breast cancer. Cancer Res 66(23):11238–11246
Noy R, Pollard JW (2014) Tumor-associated macrophages: from mechanisms to therapy. Immunity 41(1):49–61
Chang Y et al (2012) Ablation of NG2 proteoglycan leads to deficits in brown fat function and to adult onset obesity. PLoS One 7(1):e30637
Foo SS et al (2006) Ephrin-B2 controls cell motility and adhesion during blood-vessel-wall assembly. Cell 124(1):161–173
Stockmann C et al (2008) Deletion of vascular endothelial growth factor in myeloid cells accelerates tumorigenesis. Nature 456(7223):814–818
Luo Y, Radice GL (2005) N-cadherin acts upstream of VE-cadherin in controlling vascular morphogenesis. J Cell Biol 169(1):29–34
Gerhardt H, Wolburg H, Redies C (2000) N-cadherin mediates pericytic-endothelial interaction during brain angiogenesis in the chicken. Dev Dyn 218(3):472–479
Gaengel K et al (2009) Endothelial-mural cell signaling in vascular development and angiogenesis. Arterioscler Thromb Vasc Biol 29(5):630–638
Bergers G et al (2003) Benefits of targeting both pericytes and endothelial cells in the tumor vasculature with kinase inhibitors. J Clin Invest 111(9):1287–1295
Saharinen P, Alitalo K (2003) Double target for tumor mass destruction. J Clin Invest 111(9):1277–1280
Lu C et al (2007) Dual targeting of endothelial cells and pericytes in antivascular therapy for ovarian carcinoma. Clin Cancer Res 13(14):4209–4217
Brand C et al (2016) NG2 proteoglycan as a pericyte target for anticancer therapy by tumor vessel infarction with retargeted tissue factor. Oncotarget 7(6):6774–6789
Burg MA et al (1999) NG2 proteoglycan-binding peptides target tumor neovasculature. Cancer Res 59(12):2869–2874
Mills SJ, Cowin AJ, Kaur P (2013) Pericytes, mesenchymal stem cells and the wound healing process. Cell 2(3):621–634
Sa da Bandeira D, Casamitjana J, Crisan M (2017) Pericytes, integral components of adult hematopoietic stem cell niches. Pharmacol Ther 171:104–113
De Palma M et al (2005) Tie2 identifies a hematopoietic lineage of proangiogenic monocytes required for tumor vessel formation and a mesenchymal population of pericyte progenitors. Cancer Cell 8(3):211–226
Guillemin GJ, Brew BJ (2004) Microglia, macrophages, perivascular macrophages, and pericytes: a review of function and identification. J Leukoc Biol 75(3):388–397
Coffelt SB et al (2010) Elusive identities and overlapping phenotypes of proangiogenic myeloid cells in tumors. Am J Pathol 176(4):1564–1576
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Stallcup, W.B. (2018). The NG2 Proteoglycan in Pericyte Biology. In: Birbrair, A. (eds) Pericyte Biology - Novel Concepts. Advances in Experimental Medicine and Biology, vol 1109. Springer, Cham. https://doi.org/10.1007/978-3-030-02601-1_2
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