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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.

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Tissue Localization of V/P Cell Markers and PDGFRα ExpressionTissue preparations from P21 PDGFRαGFP/+;PDGFRβF5/F5 mutant mouse. Immunofluorescence was used to detect αSMA (A and B), desmin (C), β-galactosidase (D), and GFP expression for PDGFRα (A–D). (A) Kidney (200 μm vibratome section). The arrow indicates glomerulus. The asterisk indicates an arteriole. (B–D) Retina (whole-mount preparation). Arrowheads point to β-galactosidase-positive nuclei.
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pbio.0000052-g003: Tissue Localization of V/P Cell Markers and PDGFRα ExpressionTissue preparations from P21 PDGFRαGFP/+;PDGFRβF5/F5 mutant mouse. Immunofluorescence was used to detect αSMA (A and B), desmin (C), β-galactosidase (D), and GFP expression for PDGFRα (A–D). (A) Kidney (200 μm vibratome section). The arrow indicates glomerulus. The asterisk indicates an arteriole. (B–D) Retina (whole-mount preparation). Arrowheads point to β-galactosidase-positive nuclei.

Mentions: Because some populations of v/p cells appear to be more dependent on PDGFRβ signal transduction than others, we reasoned that the PDGFRα might be coexpressed in the less-affected v/p populations. Although PDGFRα has been reported in a variety of mesenchymal cell lineages (Schatteman et al. 1992; Lindahl et al. 1997b; Takakura et al. 1997; Zhang et al. 1998; Karlsson et al. 2000), we wanted to determine whether any v/p populations express the PDGFRα or whether it may be upregulated in any of the F series mice. We crossed the PDGFRαGFP line of mouse, which expresses a nuclear-localized green fluorescent protein (GFP) under the control of the PDGFRα promoter (Hamilton et al. 2003), with the F5 mutant mice and compared the GFP expression pattern to the pattern of v/p cells in the kidney, eye, and brain (Figure 3; data not shown). We have used three independent markers to designate v/p cells: smooth muscle actin α (αSMA), desmin, and the XlacZ4 transgene. Although PDGFRα-expressing cells are found in the same tissues as v/p cell markers, there is no overlapping expression of GFP with any of the v/p cell markers in the arteries or veins in the vessels of the eye and brain. PDGFRα-expressing cells are also absent from the larger vessels of the kidney, but a population of GFP+ cells is detected within the kidney glomerulus (Figure 3A). These may be either kidney mesangial cells or vascular adventitial fibroblasts. Both are populations of cells that are known to express the PDGFRα (Seifert et al. 1998). These data indicate that PDGFRα is not expressed or upregulated in two of the most affected tissues of the mutant mice, the eye and the brain, but could be functioning as a surrogate coreceptor with the PDGFRβ.


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

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

Tissue Localization of V/P Cell Markers and PDGFRα ExpressionTissue preparations from P21 PDGFRαGFP/+;PDGFRβF5/F5 mutant mouse. Immunofluorescence was used to detect αSMA (A and B), desmin (C), β-galactosidase (D), and GFP expression for PDGFRα (A–D). (A) Kidney (200 μm vibratome section). The arrow indicates glomerulus. The asterisk indicates an arteriole. (B–D) Retina (whole-mount preparation). Arrowheads point to β-galactosidase-positive nuclei.
© Copyright Policy
Related In: Results  -  Collection

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

pbio.0000052-g003: Tissue Localization of V/P Cell Markers and PDGFRα ExpressionTissue preparations from P21 PDGFRαGFP/+;PDGFRβF5/F5 mutant mouse. Immunofluorescence was used to detect αSMA (A and B), desmin (C), β-galactosidase (D), and GFP expression for PDGFRα (A–D). (A) Kidney (200 μm vibratome section). The arrow indicates glomerulus. The asterisk indicates an arteriole. (B–D) Retina (whole-mount preparation). Arrowheads point to β-galactosidase-positive nuclei.
Mentions: Because some populations of v/p cells appear to be more dependent on PDGFRβ signal transduction than others, we reasoned that the PDGFRα might be coexpressed in the less-affected v/p populations. Although PDGFRα has been reported in a variety of mesenchymal cell lineages (Schatteman et al. 1992; Lindahl et al. 1997b; Takakura et al. 1997; Zhang et al. 1998; Karlsson et al. 2000), we wanted to determine whether any v/p populations express the PDGFRα or whether it may be upregulated in any of the F series mice. We crossed the PDGFRαGFP line of mouse, which expresses a nuclear-localized green fluorescent protein (GFP) under the control of the PDGFRα promoter (Hamilton et al. 2003), with the F5 mutant mice and compared the GFP expression pattern to the pattern of v/p cells in the kidney, eye, and brain (Figure 3; data not shown). We have used three independent markers to designate v/p cells: smooth muscle actin α (αSMA), desmin, and the XlacZ4 transgene. Although PDGFRα-expressing cells are found in the same tissues as v/p cell markers, there is no overlapping expression of GFP with any of the v/p cell markers in the arteries or veins in the vessels of the eye and brain. PDGFRα-expressing cells are also absent from the larger vessels of the kidney, but a population of GFP+ cells is detected within the kidney glomerulus (Figure 3A). These may be either kidney mesangial cells or vascular adventitial fibroblasts. Both are populations of cells that are known to express the PDGFRα (Seifert et al. 1998). These data indicate that PDGFRα is not expressed or upregulated in two of the most affected tissues of the mutant mice, the eye and the brain, but could be functioning as a surrogate coreceptor with the PDGFRβ.

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
Related in: MedlinePlus