Endothelial Progenitors

• ASPP1, ASPP2
• CD105
• CD14
• CD146
• CD15
• CD34
• ASPP
• CD36
• CD45
• CD62E
• CXCR4

• ASPP1, ASPP2
  The ASPP family members ASPP1, ASPP2 (encoded by PPP1R13B and TP53BP2, respectively), act as potent activators of p53. A third member of the family, iASPP, has an inhibitory effect on apoptosis. The three members of ASPP family all bind p53 via their C-terminus, which contains a proline-rich region, four ankyrin repeats and an SH3 domain. Expression of ASPP1 and ASPP2 is frequently down-regulated in human breast tumors expressing wild-type p53. ASPP1 may also play a role in vascular development.
  
  
• CD105
  CD105 or Endoglin is a Type I transmembrane protein, which is highly expressed on human vascular endothelial cells. It exists on an O- and N-glycosylated homodimer. Up regulation of endoglin expression has been demonstrated in tumor vasculature and proliferating cells, suggesting that it is a proliferation associated endothelial marker. CD105 binds to TGF beta 1 and 3 with high affinity but not to TGF beta 2.
  
  
• CD14
  CD14 is a single copy gene encoding 2 protein forms: a 50 to 55 kDa glycosylphosphatidylinositol anchored membrane protein (mCD14) and a monocyte or liver derived soluble serum protein (sCD14) that lacks the anchor. Both molecules are critical for lipopolysaccharide (LPS) dependent signal transduction, and sCD14 confers LPS sensitivity to cells lacking mCD14. Increased sCD14 levels are associated with inflammatory infectious diseases and high mortality in gram negative shock. CD14 also appears to be involved in clearance of gram-negative bacteria via its high affinity binding to LPS-LPB complexes.Alternative names:
  • CD 105
  • END
  • Endoglin
  • ENG
  • FLJ41744
  • HHT1
  • ORW
  • ORW1
  • Osler Rendu Weber syndrome 1
  • RP11 228B15.2
  
  
  
• CD146
  CD146 belongs to the immunoglobulin supergene family with five immunoglobulin like domains (V-V-C2-C2-C2), a transmembrane region and a 63 residue cytoplasmic tail. The protein is a membrane glycoprotein that functions as a Ca2+ independent cell adhesion molecule involved in heterophilic cell-to-cell interactions. CD146 has a molecular size of 130 kDa in its reduced form (118 kDa unreduced), and N linked glycosylation accounts for fifty percent of the apparent molecular weight. In some cells the molecule carries a sulfate-3-glucuronyl moiety.
  
  Expression of the molecule was shown in a relatively limited spectrum of normal human tissues (endothelium, smooth muscle, and subpopulations of activated T cells) and malignant neoplasm (melanoma and breast carcinoma). The lineage specific expression pattern of CD146 can be useful in the differential diagnosis of certain lesions including melanomas and various types of gestational trophoblastic lesions. CD146 expression can promote tumor progression in human melanoma, through enhanced interaction between melanoma cells and endothelial cells. However, in breast carcinoma, CD146 may act as a tumor suppressor. Overexpression of CD146 in breast carcinoma cells results in a more cohesive cell growth and in the formation of smaller tumors in nude mice. During implantation and placentation, CD146 is expressed by the intermediate trophoblast in the placental site and binds to its putative receptor in uterine smooth muscle cells thus limiting trophoblastic invasion in the myometrium. Monoclonal antibody specific for CD146 is an important tool for the identification and isolation of cells expressing CD146. Alternative names:
  • A32 antigen
  • CD 146
  • Cell surface glycoprotein MUC18
  • Cell surface glycoprotein P1H12
  • MCAM
  • Melanoma adhesion molecule
  • Melanoma associated antigen A32
  • Melanoma associated glycoprotein MUC18
  • Melanoma cell adhesion molecule
  • MelCAM
  • MUC 18
  • Sendo 1
  
  
  
• CD15
  The CD15 antigen is expressed on approximately 90% human circulating granulocytes (membranes and granules), 30 to 60% of circulating monocytes and is absent from normal lymphocytes. CD15 antigen is also expressed on Reed Sternberg cells of Hodgkin's disease, on T cell lymphomas including mycosis fungoides and on some leukemias. Outside the hematopoietic system, CD15 expression is described in certain normal and neoplastic epithelial cells and in astrocytes. At least 5 major CD15 antigens (105, 135, 165, 185, 220 kDa) are present on the surface membranes of polymorphonuclear cells. The hapten occurs also in glycolipids. CD15 plays a role in mediating phagocytosis, bactericidal activity and chemotaxis. Alternative names:
  • CD 105
  • END
  • Endoglin
  • ENG
  • FLJ41744
  • HHT1
  • ORW
  • ORW1
  • Osler Rendu Weber syndrome 1
  • RP11 228B15.2
  
  
  
• CD34
  The highly glycosylated 75-120 kD antigen CD34 is possibly an adhesion molecule with a putative role in early hematopoiesis by mediating the attachment of stem cells to the bone marrow extracellular matrix or directly to stromal cells. It could act as a scaffold for the attachment of lineage specific glycans, allowing stem cells to bind to lectins expressed by stromal cells or other marrow components. CD34 is thought to have a role in presenting carbohydrate ligands to selectins. The intracellular chain of the CD34 antigen is a site of phosphorylation by activated protein kinase C, suggesting a putative role in signal transduction. Two isoforms of CD34 have been reported to be generated by alternative splicing. CD34 is highly expressed on hematopoietic progenitors, as well as on endothelial cells, brain, and testis. Staining for CD34 has been used to measure angiogenesis, which reportedly predicts tumor recurrence.
  
  
• ASPP
  The ASPP family members ASPP1, ASPP2 (encoded by PPP1R13B and TP53BP2, respectively), act as potent activators of p53. A third member of the family, iASPP, has an inhibitory effect on apoptosis. The three members of ASPP family all bind p53 via their C-terminus, which contains a proline-rich region, four ankyrin repeats and an SH3 domain. Expression of ASPP1 and ASPP2 is frequently down-regulated in human breast tumors expressing wild-type p53. ASPP1 may also play a role in vascular development.
  
  
• CD36
  CD36 is a cell surface class B scavenger receptor. CD36 is preferentially found within lipid rafts, which facilitates its association with receptors, signaling and adapter molecules. CD36 binds to collagen, thrombospondin, anionic phospholipids and oxidized LDL. May function as a cell adhesion molecule. Directly mediates cyto-adherence of Plasmodium falciparum parasitized erythrocytes. Binds long chain fatty acids and may function in the transport and/or as a regulator of fatty acid transport.
  
  
• CD45
  CD45 is a complex molecule, and is comprised of different glycoproteins ranging from 180-240 kDa. Expression of CD45 is found on all hemopoietic cells. Detection of the different isoforms can distinguish between different cell forms i.e. naive T cells and memory T cells. CD45RA is an isoform of the CD45 complex and has restricted expression between different subtypes of lymphoid cells. The functional activity of each CD45 isotype also varies. Antibodies recognizing a common epitope on all of these isoforms are termed CD45 whilst those recognizing only individual isoforms are termed CD45RA or CD45RO etc.
  
  
• CD62E
  CD62E is also known as endothelial leukocyte adhesion molecule 1 (ELAM1) or E selectin. It is a type I membrane protein that belongs to the selectin family of surface molecules (along with CD62L and CD62P). Selectins are C type cell surface lectins that play a role in leukocyte adhesion to the blood vessel wall endothelium. CD62E (E selectin) is an endothelial cell specific selectin that is expressed on cytokine induced endothelial cells only after activation with proinflammatory cytokines. In vitro experiments have shown that IL1, TNFalpha and bacterial wall components like lipopolysaccharides induce the transcription of CD62E in an NFkB dependent signaling cascade. CD62E has been associated with blood vessel endothelium in diverse inflammatory situations. The main ligands recognized by CD62E are oligosaccharides related to sialyl lewis x.
  
  
• CXCR4
  CXCR4 (fusin, LESTR or HUMSTR) is a principal coreceptor for T cell tropic strains of HIV1 fusion and entry of human white blood cells. CXCR4 is also required for the infection by dual-tropic strains of HIV1 and mediates CD4 independent infection by HIV2. The a chemokine SDF1 is the ligand for CXCR4 and prevents infection by T tropic HIV1. CXCR4 associates with the surface CD4-gp120 complex before HIV enters target cells. CXCR4 messenger RNA levels correlated with HIV1 permissiveness in diverse human cell types. Antibodies to CXCR4 block HIV1 and HIV2 fusion and infection of human target cells. The amino terminal domain and the second extracellular loop of CXCR4 serve as HIV biding sites. CXCR4 is highly expressed in brain and heart, and in white blood cells, vascular endothelial cells, and umbilical cord endothelial cells. Alternative names:
  • CD184
  • Chemokine CXC Motif Receptor 4
  • CXCR4
  • D2S201E
  • FB22
  • Fusin
  • HM89
  • HSY3RR
  • LAP3
  • LCR1
  • LESTR
  • Leukocyte-derived seven transmembrane domain receptor
  • NPY3R
  • NPYR
  • NPYRL
  • NPYY3
  • NPYY3R
  • Probable G protein coupled receptor lcr1 homolog
  • SDF-1 receptor
  • Stromal cell-derived factor 1 receptor
  • WHIM