High impact information on PTN

• HB-GAM/pleiotrophin but not RIHB/midkine enhances chondrogenesis in micromass culture [1].
• Furthermore, the distribution of HB-GAM protein in the osteoblast/osteoid layer suggests an involvement of this protein in early steps of osteogenesis [2].
• In order to study the localization of HB-GAM during chicken embryogenesis, we produced specific monoclonal antibodies to this factor [2].
• We focused our attention on the development of the tibia, where the HB-GAM protein appears at stage 27-28, i.e., just after the condensation of the mesodermal precursor cells of the chondrocytes [2].
• The heparin-binding growth-associated molecule HB-GAM (also named pleiotrophin) is a developmentally-regulated protein that belongs to a new family of heparin-binding molecules with putative functions during cell growth and differentiation [2].

Biological context of PTN

• We investigated the role of PTN in regulating the phenotype of monocytes/macrophages [3].
• CONCLUSIONS: PTN expression by monocytes/macrophages led to a downregulation of their monocytic cell markers and an upregulation of endothelial cell characteristics, thus inducing the transdifferentiation of monocytes into functional endothelial cells [3].

Anatomical context of PTN

• Pleiotrophin induces transdifferentiation of monocytes into functional endothelial cells [3].
• OBJECTIVE: Pleiotrophin (PTN) is a cytokine that is expressed by monocytes/macrophages in ischemic tissues and that promotes neovascularization, presumably by stimulating proliferation of local endothelial cells [3].
• In vivo studies showed that PTN-expressing monocytic cells incorporated into the blood vessels of the quail chorioallantoic membrane [3].
• Finally, the injection of PTN-expressing monocytes into a murine ischemic hindlimb model significantly improved perfusion of the ischemic tissue [3].
• In addition, the layer of stacked cells surrounding the cartilage core (usually considered as the osteoprogenitor cells) clearly expresses the HB-GAM message between stages 30-37 whereas differentiated osteoblasts do not [2].

Analytical, diagnostic and therapeutic context of PTN

• We present an investigation of the HB-GAM mRNA expression and HB-GAM protein distribution in the developing leg by in situ hybridization and immunocytochemical studies [2].

References