Limits...
Dally Proteoglycan Mediates the Autonomous and Nonautonomous Effects on Tissue Growth Caused by Activation of the PI3K and TOR Pathways.

Ferreira A, Milán M - PLoS Biol. (2015)

Bottom Line: Activation of these pathways leads to an autonomous induction of tissue overgrowth and to a remarkable nonautonomous reduction in growth and proliferation rates of adjacent cell populations.The observed autonomous and nonautonomous effects on tissue growth rely on the up-regulation of the proteoglycan Dally, a major element involved in modulating the spreading, stability, and activity of the growth promoting Decapentaplegic (Dpp)/transforming growth factor β(TGF-β) signaling molecule.Our findings indicate that a reduction in the amount of available growth factors contributes to the outcompetition of wild-type cells by overgrowing cell populations.

View Article: PubMed Central - PubMed

Affiliation: Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.

ABSTRACT
How cells acquiring mutations in tumor suppressor genes outcompete neighboring wild-type cells is poorly understood. The phosphatidylinositol 3-kinase (PI3K)-phosphatase with tensin homology (PTEN) and tuberous sclerosis complex (TSC)-target of rapamycin (TOR) pathways are frequently activated in human cancer, and this activation is often causative of tumorigenesis. We utilized the Gal4-UAS system in Drosophila imaginal primordia, highly proliferative and growing tissues, to analyze the impact of restricted activation of these pathways on neighboring wild-type cell populations. Activation of these pathways leads to an autonomous induction of tissue overgrowth and to a remarkable nonautonomous reduction in growth and proliferation rates of adjacent cell populations. This nonautonomous response occurs independently of where these pathways are activated, is functional all throughout development, takes place across compartments, and is distinct from cell competition. The observed autonomous and nonautonomous effects on tissue growth rely on the up-regulation of the proteoglycan Dally, a major element involved in modulating the spreading, stability, and activity of the growth promoting Decapentaplegic (Dpp)/transforming growth factor β(TGF-β) signaling molecule. Our findings indicate that a reduction in the amount of available growth factors contributes to the outcompetition of wild-type cells by overgrowing cell populations. During normal development, the PI3K/PTEN and TSC/TOR pathways play a major role in sensing nutrient availability and modulating the final size of any developing organ. We present evidence that Dally also contributes to integrating nutrient sensing and organ scaling, the fitting of pattern to size.

No MeSH data available.


Related in: MedlinePlus

Nonautonomous effects on tissue size upon targeted activation of PI3K/PTEN and TSC/TOR pathways.(A, E, I) Schemes of adult wings with the nub (A), ci (E), and en (I) expression domains marked in blue and cuticle preparations of male adult wings expressing GFP or PTENRNAi under the control of the nub-gal4 (A), ci-gal4 (E), and en-gal4 (I) drivers. The blue line marks the boundary between anterior (A) and posterior (P) compartments. The wing is decorated with four longitudinal veins (L2–L5), and the anterior side of L4 corresponds to the AP compartment boundary. (B–D, F–H, J–L) Histograms plotting tissue size (B, C, F, G, J, K) and cell density (D, H, L) of the whole wing (B, F, J), or the A and P compartments of adult wings expressing the indicated transgenes in the nub (B–D), ci (F–H) or en (J–L) domains normalized as a percent of the control wings. Note a consistent reduction in tissue size of the adjacent cell populations in G and K (white bars). (M) Cuticle preparation of a ci>stg, cycE adult wing. The blue line marks the boundary between the A and P compartments. On the right are histograms plotting tissue size and cell density values of the A (blue bars) and P (white bars) domains of ci>stg, cycE adult wings normalized as a percent of the control (ci>GFP) wings. ci-gal4 drives gene expression to the A compartment of the wing. (N) Cuticle preparations of spaltPE>GFP and spaltPE>PTENRNAi adult wings. The blue lines mark the lateral and medial regions of the wing. On the right are histograms plotting tissue size and cell density values of the medial (blue bars) and lateral (white bars) regions of spaltPE>PTENRNAi adult wings normalized as a percent of the control (spaltPE>GFP) wings. spalt-gal4 drives gene expression to the medial part of the wing. The domains of transgene expression in A, E, I, M, and N are marked with a blue asterisk. Error bars show the standard deviation. Number of wings analyzed per genotype ≥ 10. ***p < 0.001; **p < 0.01; *p < 0.05. Area and cell density values of the cell populations driving transgene expression are labeled in blue, and the values of the nonexpressing domain are represented in white.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4551486&req=5

pbio.1002239.g001: Nonautonomous effects on tissue size upon targeted activation of PI3K/PTEN and TSC/TOR pathways.(A, E, I) Schemes of adult wings with the nub (A), ci (E), and en (I) expression domains marked in blue and cuticle preparations of male adult wings expressing GFP or PTENRNAi under the control of the nub-gal4 (A), ci-gal4 (E), and en-gal4 (I) drivers. The blue line marks the boundary between anterior (A) and posterior (P) compartments. The wing is decorated with four longitudinal veins (L2–L5), and the anterior side of L4 corresponds to the AP compartment boundary. (B–D, F–H, J–L) Histograms plotting tissue size (B, C, F, G, J, K) and cell density (D, H, L) of the whole wing (B, F, J), or the A and P compartments of adult wings expressing the indicated transgenes in the nub (B–D), ci (F–H) or en (J–L) domains normalized as a percent of the control wings. Note a consistent reduction in tissue size of the adjacent cell populations in G and K (white bars). (M) Cuticle preparation of a ci>stg, cycE adult wing. The blue line marks the boundary between the A and P compartments. On the right are histograms plotting tissue size and cell density values of the A (blue bars) and P (white bars) domains of ci>stg, cycE adult wings normalized as a percent of the control (ci>GFP) wings. ci-gal4 drives gene expression to the A compartment of the wing. (N) Cuticle preparations of spaltPE>GFP and spaltPE>PTENRNAi adult wings. The blue lines mark the lateral and medial regions of the wing. On the right are histograms plotting tissue size and cell density values of the medial (blue bars) and lateral (white bars) regions of spaltPE>PTENRNAi adult wings normalized as a percent of the control (spaltPE>GFP) wings. spalt-gal4 drives gene expression to the medial part of the wing. The domains of transgene expression in A, E, I, M, and N are marked with a blue asterisk. Error bars show the standard deviation. Number of wings analyzed per genotype ≥ 10. ***p < 0.001; **p < 0.01; *p < 0.05. Area and cell density values of the cell populations driving transgene expression are labeled in blue, and the values of the nonexpressing domain are represented in white.

Mentions: The activation of the PI3K/PTEN and TSC/TOR pathways induces tissue growth in the developing imaginal primordia and gives rise to overgrown adult structures [19–23]. Interestingly, these pathways exert this action by affecting cell size and cell proliferation in different manners. Activation of the PI3K/PTEN pathway in the whole wing (with the nubbin-gal4 driver, Fig 1A), either by expression of PI3K-92E (also termed Drosophila p110 or Dp110) or a double-stranded RNA (dsRNA) form of PTEN (a negative regulator of PI3K/Dp110), gave rise to larger wings than those of control flies expressing green fluorescent protein (GFP) (Fig 1A and 1B). The increase in tissue size was a consequence of both an increase in cell size (reflected by a reduction in cell densities in the adult wing, Fig 1D) and in cell number (note the increase in tissue size in Fig 1B and 1C is much larger than the reduction in cell densities in Fig 1D). Activation of the TOR pathway, by depletion of TSC1 or TSC2, leads to strongly overgrown tissues and larval lethality [24]. In order to reduce larval lethality and to analyze the resulting adult wings, we induced mild activation of the TOR pathway by overexpressing the guanosine-5'-triphosphate (GTP)-binding protein Rheb, which binds and activates TOR [25–27]. Rheb overexpression gives rise to overgrown adult wings (Fig 1B). The observed increase in tissue size is mainly a consequence of an increase in cell size (Fig 1D, note the reduction in cell densities is to a similar extent as the increase in tissue size shown in Fig 1B and 1C). The adult wing is subdivided into an anterior (A) and a posterior (P) compartment, and the boundary between these two cell populations is easily identified in the adult wing (Fig 1A), as it corresponds to the anterior side of the fourth longitudinal vein (L4, Fig 1A). The observed increase in tissue size upon activation of the PI3K/PTEN or TSC/TOR pathways in the whole wing was similar in both compartments (Fig 1C).


Dally Proteoglycan Mediates the Autonomous and Nonautonomous Effects on Tissue Growth Caused by Activation of the PI3K and TOR Pathways.

Ferreira A, Milán M - PLoS Biol. (2015)

Nonautonomous effects on tissue size upon targeted activation of PI3K/PTEN and TSC/TOR pathways.(A, E, I) Schemes of adult wings with the nub (A), ci (E), and en (I) expression domains marked in blue and cuticle preparations of male adult wings expressing GFP or PTENRNAi under the control of the nub-gal4 (A), ci-gal4 (E), and en-gal4 (I) drivers. The blue line marks the boundary between anterior (A) and posterior (P) compartments. The wing is decorated with four longitudinal veins (L2–L5), and the anterior side of L4 corresponds to the AP compartment boundary. (B–D, F–H, J–L) Histograms plotting tissue size (B, C, F, G, J, K) and cell density (D, H, L) of the whole wing (B, F, J), or the A and P compartments of adult wings expressing the indicated transgenes in the nub (B–D), ci (F–H) or en (J–L) domains normalized as a percent of the control wings. Note a consistent reduction in tissue size of the adjacent cell populations in G and K (white bars). (M) Cuticle preparation of a ci>stg, cycE adult wing. The blue line marks the boundary between the A and P compartments. On the right are histograms plotting tissue size and cell density values of the A (blue bars) and P (white bars) domains of ci>stg, cycE adult wings normalized as a percent of the control (ci>GFP) wings. ci-gal4 drives gene expression to the A compartment of the wing. (N) Cuticle preparations of spaltPE>GFP and spaltPE>PTENRNAi adult wings. The blue lines mark the lateral and medial regions of the wing. On the right are histograms plotting tissue size and cell density values of the medial (blue bars) and lateral (white bars) regions of spaltPE>PTENRNAi adult wings normalized as a percent of the control (spaltPE>GFP) wings. spalt-gal4 drives gene expression to the medial part of the wing. The domains of transgene expression in A, E, I, M, and N are marked with a blue asterisk. Error bars show the standard deviation. Number of wings analyzed per genotype ≥ 10. ***p < 0.001; **p < 0.01; *p < 0.05. Area and cell density values of the cell populations driving transgene expression are labeled in blue, and the values of the nonexpressing domain are represented in white.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4551486&req=5

pbio.1002239.g001: Nonautonomous effects on tissue size upon targeted activation of PI3K/PTEN and TSC/TOR pathways.(A, E, I) Schemes of adult wings with the nub (A), ci (E), and en (I) expression domains marked in blue and cuticle preparations of male adult wings expressing GFP or PTENRNAi under the control of the nub-gal4 (A), ci-gal4 (E), and en-gal4 (I) drivers. The blue line marks the boundary between anterior (A) and posterior (P) compartments. The wing is decorated with four longitudinal veins (L2–L5), and the anterior side of L4 corresponds to the AP compartment boundary. (B–D, F–H, J–L) Histograms plotting tissue size (B, C, F, G, J, K) and cell density (D, H, L) of the whole wing (B, F, J), or the A and P compartments of adult wings expressing the indicated transgenes in the nub (B–D), ci (F–H) or en (J–L) domains normalized as a percent of the control wings. Note a consistent reduction in tissue size of the adjacent cell populations in G and K (white bars). (M) Cuticle preparation of a ci>stg, cycE adult wing. The blue line marks the boundary between the A and P compartments. On the right are histograms plotting tissue size and cell density values of the A (blue bars) and P (white bars) domains of ci>stg, cycE adult wings normalized as a percent of the control (ci>GFP) wings. ci-gal4 drives gene expression to the A compartment of the wing. (N) Cuticle preparations of spaltPE>GFP and spaltPE>PTENRNAi adult wings. The blue lines mark the lateral and medial regions of the wing. On the right are histograms plotting tissue size and cell density values of the medial (blue bars) and lateral (white bars) regions of spaltPE>PTENRNAi adult wings normalized as a percent of the control (spaltPE>GFP) wings. spalt-gal4 drives gene expression to the medial part of the wing. The domains of transgene expression in A, E, I, M, and N are marked with a blue asterisk. Error bars show the standard deviation. Number of wings analyzed per genotype ≥ 10. ***p < 0.001; **p < 0.01; *p < 0.05. Area and cell density values of the cell populations driving transgene expression are labeled in blue, and the values of the nonexpressing domain are represented in white.
Mentions: The activation of the PI3K/PTEN and TSC/TOR pathways induces tissue growth in the developing imaginal primordia and gives rise to overgrown adult structures [19–23]. Interestingly, these pathways exert this action by affecting cell size and cell proliferation in different manners. Activation of the PI3K/PTEN pathway in the whole wing (with the nubbin-gal4 driver, Fig 1A), either by expression of PI3K-92E (also termed Drosophila p110 or Dp110) or a double-stranded RNA (dsRNA) form of PTEN (a negative regulator of PI3K/Dp110), gave rise to larger wings than those of control flies expressing green fluorescent protein (GFP) (Fig 1A and 1B). The increase in tissue size was a consequence of both an increase in cell size (reflected by a reduction in cell densities in the adult wing, Fig 1D) and in cell number (note the increase in tissue size in Fig 1B and 1C is much larger than the reduction in cell densities in Fig 1D). Activation of the TOR pathway, by depletion of TSC1 or TSC2, leads to strongly overgrown tissues and larval lethality [24]. In order to reduce larval lethality and to analyze the resulting adult wings, we induced mild activation of the TOR pathway by overexpressing the guanosine-5'-triphosphate (GTP)-binding protein Rheb, which binds and activates TOR [25–27]. Rheb overexpression gives rise to overgrown adult wings (Fig 1B). The observed increase in tissue size is mainly a consequence of an increase in cell size (Fig 1D, note the reduction in cell densities is to a similar extent as the increase in tissue size shown in Fig 1B and 1C). The adult wing is subdivided into an anterior (A) and a posterior (P) compartment, and the boundary between these two cell populations is easily identified in the adult wing (Fig 1A), as it corresponds to the anterior side of the fourth longitudinal vein (L4, Fig 1A). The observed increase in tissue size upon activation of the PI3K/PTEN or TSC/TOR pathways in the whole wing was similar in both compartments (Fig 1C).

Bottom Line: Activation of these pathways leads to an autonomous induction of tissue overgrowth and to a remarkable nonautonomous reduction in growth and proliferation rates of adjacent cell populations.The observed autonomous and nonautonomous effects on tissue growth rely on the up-regulation of the proteoglycan Dally, a major element involved in modulating the spreading, stability, and activity of the growth promoting Decapentaplegic (Dpp)/transforming growth factor β(TGF-β) signaling molecule.Our findings indicate that a reduction in the amount of available growth factors contributes to the outcompetition of wild-type cells by overgrowing cell populations.

View Article: PubMed Central - PubMed

Affiliation: Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.

ABSTRACT
How cells acquiring mutations in tumor suppressor genes outcompete neighboring wild-type cells is poorly understood. The phosphatidylinositol 3-kinase (PI3K)-phosphatase with tensin homology (PTEN) and tuberous sclerosis complex (TSC)-target of rapamycin (TOR) pathways are frequently activated in human cancer, and this activation is often causative of tumorigenesis. We utilized the Gal4-UAS system in Drosophila imaginal primordia, highly proliferative and growing tissues, to analyze the impact of restricted activation of these pathways on neighboring wild-type cell populations. Activation of these pathways leads to an autonomous induction of tissue overgrowth and to a remarkable nonautonomous reduction in growth and proliferation rates of adjacent cell populations. This nonautonomous response occurs independently of where these pathways are activated, is functional all throughout development, takes place across compartments, and is distinct from cell competition. The observed autonomous and nonautonomous effects on tissue growth rely on the up-regulation of the proteoglycan Dally, a major element involved in modulating the spreading, stability, and activity of the growth promoting Decapentaplegic (Dpp)/transforming growth factor β(TGF-β) signaling molecule. Our findings indicate that a reduction in the amount of available growth factors contributes to the outcompetition of wild-type cells by overgrowing cell populations. During normal development, the PI3K/PTEN and TSC/TOR pathways play a major role in sensing nutrient availability and modulating the final size of any developing organ. We present evidence that Dally also contributes to integrating nutrient sensing and organ scaling, the fitting of pattern to size.

No MeSH data available.


Related in: MedlinePlus