Limits...
Additive effects of PDGF receptor beta signaling pathways in vascular smooth muscle cell development.

Tallquist MD, French WJ, Soriano P - PLoS Biol. (2003)

Bottom Line: A decrease in either receptor expression levels or disruption of multiple downstream signaling pathways lead to a significant reduction in v/p.Conversely, loss of RasGAP binding leads to an increase in this same cell population, implicating a potential role for this effector in attenuating the PDGFRbeta signal.The combined in vivo and biochemical data suggest that the summation of pathways associated with the PDGFRbeta signal transduction determines the expansion of developing v/p cells.

View Article: PubMed Central - PubMed

Affiliation: Program in Developmental Biology and Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA. michelle.tallquist@utsouthwestern.edu

ABSTRACT
The platelet-derived growth factor beta receptor (PDGFRbeta) is known to activate many molecules involved in signal transduction and has been a paradigm for receptor tyrosine kinase signaling for many years. We have sought to determine the role of individual signaling components downstream of this receptor in vivo by analyzing an allelic series of tyrosine-phenylalanine mutations that prevent binding of specific signal transduction components. Here we show that the incidence of vascular smooth muscle cells/pericytes (v/p), a PDGFRbeta-dependent cell type, can be correlated to the amount of receptor expressed and the number of activated signal transduction pathways. A decrease in either receptor expression levels or disruption of multiple downstream signaling pathways lead to a significant reduction in v/p. Conversely, loss of RasGAP binding leads to an increase in this same cell population, implicating a potential role for this effector in attenuating the PDGFRbeta signal. The combined in vivo and biochemical data suggest that the summation of pathways associated with the PDGFRbeta signal transduction determines the expansion of developing v/p cells.

Show MeSH
PDGFRβ Allelic SeriesThis figure depicts the mutant alleles generated in the mouse PDGFRβ genomic locus. X represents a mutation in the tyrosine-binding site(s) for a particular signal transduction molecule. The F7 allele contains a disruption in one SFK-binding site because loss of both sites results in diminished kinase activity (Mori et al. 1993). The truncation allele (βT) was created by deletion and subsequent frameshift that results in a stop codon 32 amino acids past the RasGAP-binding site.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC261889&req=5

pbio.0000052-g001: PDGFRβ Allelic SeriesThis figure depicts the mutant alleles generated in the mouse PDGFRβ genomic locus. X represents a mutation in the tyrosine-binding site(s) for a particular signal transduction molecule. The F7 allele contains a disruption in one SFK-binding site because loss of both sites results in diminished kinase activity (Mori et al. 1993). The truncation allele (βT) was created by deletion and subsequent frameshift that results in a stop codon 32 amino acids past the RasGAP-binding site.

Mentions: To examine the roles of PI3K and PLCγ downstream of the PDGFRβ, we have previously disrupted their binding sites in the receptor's cytoplasmic domain (Heuchel et al. 1999; Tallquist et al. 2000). Surprisingly, no overt phenotypes were detected in homozygous mutants lacking these two pathways, and deficiencies were observed only when the animals were challenged physiologically. To assess the roles of the remaining signal transduction pathways, we have created a PDGFRβ allelic series in mice (Figure 1). We refer to this series as the F series because it contains Y–F mutations at the known phosphorylated tyrosine residues. Using v/p cell number as a readout for PDGFRβ signal transduction, we have determined that the level of receptor expressed as well as the sum of signaling pathways induced by the PDGFRβ determines the number of v/p cells that form. These results provide an example of RTK signal transduction quantitatively controlling cellular development.


Additive effects of PDGF receptor beta signaling pathways in vascular smooth muscle cell development.

Tallquist MD, French WJ, Soriano P - PLoS Biol. (2003)

PDGFRβ Allelic SeriesThis figure depicts the mutant alleles generated in the mouse PDGFRβ genomic locus. X represents a mutation in the tyrosine-binding site(s) for a particular signal transduction molecule. The F7 allele contains a disruption in one SFK-binding site because loss of both sites results in diminished kinase activity (Mori et al. 1993). The truncation allele (βT) was created by deletion and subsequent frameshift that results in a stop codon 32 amino acids past the RasGAP-binding site.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC261889&req=5

pbio.0000052-g001: PDGFRβ Allelic SeriesThis figure depicts the mutant alleles generated in the mouse PDGFRβ genomic locus. X represents a mutation in the tyrosine-binding site(s) for a particular signal transduction molecule. The F7 allele contains a disruption in one SFK-binding site because loss of both sites results in diminished kinase activity (Mori et al. 1993). The truncation allele (βT) was created by deletion and subsequent frameshift that results in a stop codon 32 amino acids past the RasGAP-binding site.
Mentions: To examine the roles of PI3K and PLCγ downstream of the PDGFRβ, we have previously disrupted their binding sites in the receptor's cytoplasmic domain (Heuchel et al. 1999; Tallquist et al. 2000). Surprisingly, no overt phenotypes were detected in homozygous mutants lacking these two pathways, and deficiencies were observed only when the animals were challenged physiologically. To assess the roles of the remaining signal transduction pathways, we have created a PDGFRβ allelic series in mice (Figure 1). We refer to this series as the F series because it contains Y–F mutations at the known phosphorylated tyrosine residues. Using v/p cell number as a readout for PDGFRβ signal transduction, we have determined that the level of receptor expressed as well as the sum of signaling pathways induced by the PDGFRβ determines the number of v/p cells that form. These results provide an example of RTK signal transduction quantitatively controlling cellular development.

Bottom Line: A decrease in either receptor expression levels or disruption of multiple downstream signaling pathways lead to a significant reduction in v/p.Conversely, loss of RasGAP binding leads to an increase in this same cell population, implicating a potential role for this effector in attenuating the PDGFRbeta signal.The combined in vivo and biochemical data suggest that the summation of pathways associated with the PDGFRbeta signal transduction determines the expansion of developing v/p cells.

View Article: PubMed Central - PubMed

Affiliation: Program in Developmental Biology and Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA. michelle.tallquist@utsouthwestern.edu

ABSTRACT
The platelet-derived growth factor beta receptor (PDGFRbeta) is known to activate many molecules involved in signal transduction and has been a paradigm for receptor tyrosine kinase signaling for many years. We have sought to determine the role of individual signaling components downstream of this receptor in vivo by analyzing an allelic series of tyrosine-phenylalanine mutations that prevent binding of specific signal transduction components. Here we show that the incidence of vascular smooth muscle cells/pericytes (v/p), a PDGFRbeta-dependent cell type, can be correlated to the amount of receptor expressed and the number of activated signal transduction pathways. A decrease in either receptor expression levels or disruption of multiple downstream signaling pathways lead to a significant reduction in v/p. Conversely, loss of RasGAP binding leads to an increase in this same cell population, implicating a potential role for this effector in attenuating the PDGFRbeta signal. The combined in vivo and biochemical data suggest that the summation of pathways associated with the PDGFRbeta signal transduction determines the expansion of developing v/p cells.

Show MeSH