PDGFRα Expression During Mouse Embryogenesis: Immunolocalization Analyzed by Whole-mount Immunohistostaining Using the Monoclonal Anti-mouse PDGFRα Antibody APA5

Abstract

SUMMARYWe investigated the cells that express platelet-derived growth factor receptor ␣ (PDGFR ␣) during mouse embryogenesis. PDGFR ␣ expression has been identified by in situ hybridization or immunohistochemistry using polyclonal antibodies on tissue sections. Because no immunostaining study using whole-mount specimens has been published to date, we established a new monoclonal antibody (MAb), APA5, for this purpose. Our results differed in that APA5 stained only the paraxial mesoderm, whereas other investigators concluded that most if not all mesodermal cells expressed PDGFR ␣. Moreover, we did not find PDGFR ␣ expression in embryonic erythrocytes, which have been previously suggested to express PDGFR ␣. On the basis of our present results, we wish to revise the proposed PDGFR ␣ expression as follows. At the pregastrulation stage, PDGFR ␣ is expressed only in primitive endoderm, particularly that in the ectoplacental cone. On gastrulation, it is expressed at high levels in the paraxial mesoderm. This expression continues after its differentiation into the somite. Along with the differentiation and migration of the sclerotome, PDGFR ␣ ϩ cells begin to become distributed throughout the embryonal mesenchyme. During organogenesis, particularly intense staining is detected in regions of epithelial and mesenchymal interaction, such as the tooth bud and bronchi. In addition to mesodermal derivatives, the developing lens, apical ectodermal ridge, glial precursor, cardiac valves, and choroid plexus express PDGFR ␣. Our results with whole-mount immunostaining show that PDGFR ␣ is abundantly expressed and may play important roles during embryogenesis.

PDGF‐A as an epicardial mitogen during heart development

“…Neither mRNA was detected in E9.5 hearts (data not shown). In the literature, Pdgfra has been described without further clarification or attention as being expressed in the embryonic mouse "pericardium," both at the RNA level Schatteman et al, 1992;Lakkis and Epstein, 1998) and at the protein level (Takakura et al, 1997), which from our results we now recognize to be the epicardium. There is also published evidence for low level expression in myocardium (see the Discussion section).…”

Defining the earliest step of cardiovascular progenitor specification during embryonic stem cell differentiation

“…Mesp1 GFP ESCs will be a powerful method to screen for new intrinsic and extrinsic regulators of cardiovascular progenitor specifi cation and differentiation. Takakura et al, 1997), and lineage tracing has shown that Flk1 expressing cells give rise to all cardiovascular lineages (Ema et al, 2006), suggesting that these markers could be used in future studies to isolate the early MCPs during mouse embry onic development.…”

Angiogenic activity of endothelial progenitor cells through angiopoietin-1 and angiopoietin-2

“…Immunocytochemistry GFP-positive EPCs were subjected to an immunocytochemistry assay as previously described (Takakura et al 1997). In brief, mice were sacrificed under anesthesia by cervical dislocation; the femurs of mice were flushed with PBS and cultured on fibronectin-coated 24-well plates in EGM-2 Supplement Pack with Ang-1 and Ang-2 for 7 days.…”