CD105 (endoglin) expression on hematopoietic stem/progenitor cells.
Endoglin (CD105) is a component of the transforming growth factor-beta (TGF-beta) receptor (TGF-betaR) complex. Together with betaglycan, CD105 is considered as a TGF-betaR accessory molecule (also called TGF-betaRIII), but its functions in the receptor-ligand interactions are still poorly understood. A small subset of human CD34+ hematopoietic stem/progenitor cells that has phenotypic and functional features suggestive of very primitive hematopoietic cells expresses the CD105 antigen. CD34+/CD105+ cells recirculate in the peripheral blood of mobilized subjects and can be purified by immunomagnetic isolation strategies. The hematopoietic potential of these CD34+/CD105+ cells appears to be sustained by a combination of hematopoietic and non-hematopoietic cytokines, which comprises Flt3 ligand, erythropoietin, interleukin-15 and vascular endothelial growth factor. Endogenous TGF-beta1 is a crucial factor for the maintenance of CD34+/CD105+ immaturity acting through positive modulation of both CD105 and CD34 molecules in the absence of relevant effects on the cell cycle profile. CD105 is absent on very primitive CD34-/lineage-/CD45+ (CD34-Lin-) human hematopoietic cells isolated from cord blood. However, in vitro exposure of CD34-Lin- cells to exogenous TGF-beta1 causes the appearance of a discrete population of CD34+/CD105+ cells. Collectively, available data on CD105 expression and function in primitive hematopoiesis indicate that this molecule could cooperate with the dissociation of TGF-beta1 cell cycle effects from its other effects on cell survival and differentiation.
Pierelli
L
L
Istituto di Ostetricia e Ginecologia, Universita' Cattolica S. Cuore, Roma, Italy. luca@pierelli.it
Bonanno
G
G
Rutella
S
S
Marone
M
M
Scambia
G
G
Leone
G
G
D015703:Antigens, CD; D018952:Antigens, CD34 / Q000032:analysis; D000071063:Endoglin; D006412:Hematopoietic Stem Cells / Q000737:chemistry*; D006801:Humans; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta / Q000032:analysis; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000032:analysis*
D015703:Antigens, CD; D018952:Antigens, CD34; C064206:ENG protein, human; D000071063:Endoglin; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D019010:Vascular Cell Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II