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The Spalt Transcription Factors Generate the Transcriptional Landscape of the Drosophila melanogaster Wing Pouch Central Region.

Organista MF, Martín M, de Celis JM, Barrio R, López-Varea A, Esteban N, Casado M, de Celis JF - PLoS Genet. (2015)

Bottom Line: The Drosophila genes spalt major (salm) and spalt-related (salr) encode Zn-finger transcription factors regulated by the Decapentaplegic (Dpp) signalling pathway in the wing imaginal disc.We studied by in situ hybridization the expression pattern of the genes whose mRNA levels varied significantly, and uncovered a complex transcription landscape regulated by the Spalt proteins in the wing disc.Furthermore, loss-of-function phenotypic analysis of these genes indicates, for a fraction of them, a requirement for wing growth and patterning.

View Article: PubMed Central - PubMed

Affiliation: Centro de Biología Molecular Severo Ochoa, CSIC and Universidad Autónoma de Madrid, C/Nicolás Cabrera, 1. Universidad Autónoma de Madrid, Madrid, Spain.

ABSTRACT
The Drosophila genes spalt major (salm) and spalt-related (salr) encode Zn-finger transcription factors regulated by the Decapentaplegic (Dpp) signalling pathway in the wing imaginal disc. The function of these genes is required for cell survival and proliferation in the central region of the wing disc, and also for vein patterning in the lateral regions. The identification of direct Salm and Salr target genes, and the analysis of their functions, are critical steps towards understanding the genetic control of growth and patterning of the Drosophila wing imaginal disc by the Dpp pathway. To identify candidate Salm/Salr target genes, we have compared the expression profile of salm/salr knockdown wing discs with control discs in microarray experiments. We studied by in situ hybridization the expression pattern of the genes whose mRNA levels varied significantly, and uncovered a complex transcription landscape regulated by the Spalt proteins in the wing disc. Interestingly, candidate Salm/Salr targets include genes which expression is turned off and genes which expression is positively regulated by Salm/Salr. Furthermore, loss-of-function phenotypic analysis of these genes indicates, for a fraction of them, a requirement for wing growth and patterning. The identification and analysis of candidate Salm/Salr target genes opens a new avenue to reconstruct the genetic structure of the wing, linking the activity of the Dpp pathway to the development of this epithelial tissue.

No MeSH data available.


Related in: MedlinePlus

Genes regulated by Dpp signalling independently of Salm/Salr.(A) Control salEPv-Gal4 UAS-GFP/+ wing. (B) Control third instar wing disc showing Spalt major expression (Red). (C-C’) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing disc showing Salm (red in C and C’) and GFP expression (green in C). (D) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing. (E) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm wing. (F) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salr wing. Forced expression of Salm (E) or Salr (F) in the central region of salEPv-Gal4 UAS-GFP;UAS-dad (D) discs partially rescues the size and pattern defects caused by Dad over-expression. (G-G’’’) CG32372 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (G), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (G’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (G’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (G’’’). (H-H’’’) CG17278 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (H), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (H’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (H’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (H’’’). The over-expression of Salm does not rescue the loss of CG32372 or CG17278 expression caused by increased Dad expression.
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pgen.1005370.g005: Genes regulated by Dpp signalling independently of Salm/Salr.(A) Control salEPv-Gal4 UAS-GFP/+ wing. (B) Control third instar wing disc showing Spalt major expression (Red). (C-C’) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing disc showing Salm (red in C and C’) and GFP expression (green in C). (D) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing. (E) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm wing. (F) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salr wing. Forced expression of Salm (E) or Salr (F) in the central region of salEPv-Gal4 UAS-GFP;UAS-dad (D) discs partially rescues the size and pattern defects caused by Dad over-expression. (G-G’’’) CG32372 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (G), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (G’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (G’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (G’’’). (H-H’’’) CG17278 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (H), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (H’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (H’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (H’’’). The over-expression of Salm does not rescue the loss of CG32372 or CG17278 expression caused by increased Dad expression.

Mentions: For a 22% of the analysed cases we could not detect a change in the expression pattern comparing wild type and salm/salr knockdown discs (Fig 4A, Fig 4D-4D’, Fig 4G-4G’ and S13 Fig). We wondered whether some of these genes were regulated by the Dpp pathway, independently of Spalt, in the central region of the wing. To reduce Dpp activity we over-expressed Dad in this territory (salEPv-Gal4; UAS-dad; Fig 5A–5D). In this background the expression of Sal was strongly reduced (Fig 5C-5C’; compared with Fig 5B) and the resulting adult wing display a moderate to strong Dpp phenotype (Fig 5D), that could be partially rescued by the co-expression of either Salm (Fig 5E) or Salr (Fig 5F). Indeed, we found that the expression of CG32372 (Fig 5G-5G’’’) and CG17278 (Fig 5H-5H’’’) are not strongly affected in salm-i/salr-i discs (Fig 5G’, 5H’ and 5I’), but are reduced or absent in UAS-dad discs (Fig 5G’’ and 5H’’). Because the loss of CG32372 and CG17278 in UAS-dad discs cannot be rescued by the over-expression of Salm (Fig 5G’’’ and 5H’’’), we suggest that these genes are likely candidates for Dpp regulation independently of Salm/Salr. Indeed, CG32372 corresponds to larval translucida, a gene which expression was already shown to be regulated by Dpp [32]. We assume that genes expressed in the central domain of the wing disc and regulated by Dpp will be picked up in our microarray experiments as Sal-, because the extent of this territory is reduced in salm/salr knockdown discs.


The Spalt Transcription Factors Generate the Transcriptional Landscape of the Drosophila melanogaster Wing Pouch Central Region.

Organista MF, Martín M, de Celis JM, Barrio R, López-Varea A, Esteban N, Casado M, de Celis JF - PLoS Genet. (2015)

Genes regulated by Dpp signalling independently of Salm/Salr.(A) Control salEPv-Gal4 UAS-GFP/+ wing. (B) Control third instar wing disc showing Spalt major expression (Red). (C-C’) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing disc showing Salm (red in C and C’) and GFP expression (green in C). (D) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing. (E) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm wing. (F) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salr wing. Forced expression of Salm (E) or Salr (F) in the central region of salEPv-Gal4 UAS-GFP;UAS-dad (D) discs partially rescues the size and pattern defects caused by Dad over-expression. (G-G’’’) CG32372 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (G), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (G’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (G’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (G’’’). (H-H’’’) CG17278 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (H), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (H’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (H’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (H’’’). The over-expression of Salm does not rescue the loss of CG32372 or CG17278 expression caused by increased Dad expression.
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getmorefigures.php?uid=PMC4524721&req=5

pgen.1005370.g005: Genes regulated by Dpp signalling independently of Salm/Salr.(A) Control salEPv-Gal4 UAS-GFP/+ wing. (B) Control third instar wing disc showing Spalt major expression (Red). (C-C’) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing disc showing Salm (red in C and C’) and GFP expression (green in C). (D) salEPv-Gal4 UAS-GFP/+; UAS-dad/+ wing. (E) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm wing. (F) salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salr wing. Forced expression of Salm (E) or Salr (F) in the central region of salEPv-Gal4 UAS-GFP;UAS-dad (D) discs partially rescues the size and pattern defects caused by Dad over-expression. (G-G’’’) CG32372 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (G), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (G’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (G’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (G’’’). (H-H’’’) CG17278 in situ hybridization in third instar discs of salEPv-Gal4 UAS-GFP/+ (H), salEPv-Gal4 UAS-GFP/UAS-salm-i; UAS-salr-i/+ (H’), salEPv-Gal4 UAS-GFP/+; UAS-dad/+ (H’’) and salEPv-Gal4 UAS-GFP/+; UAS-dad/UAS-salm (H’’’). The over-expression of Salm does not rescue the loss of CG32372 or CG17278 expression caused by increased Dad expression.
Mentions: For a 22% of the analysed cases we could not detect a change in the expression pattern comparing wild type and salm/salr knockdown discs (Fig 4A, Fig 4D-4D’, Fig 4G-4G’ and S13 Fig). We wondered whether some of these genes were regulated by the Dpp pathway, independently of Spalt, in the central region of the wing. To reduce Dpp activity we over-expressed Dad in this territory (salEPv-Gal4; UAS-dad; Fig 5A–5D). In this background the expression of Sal was strongly reduced (Fig 5C-5C’; compared with Fig 5B) and the resulting adult wing display a moderate to strong Dpp phenotype (Fig 5D), that could be partially rescued by the co-expression of either Salm (Fig 5E) or Salr (Fig 5F). Indeed, we found that the expression of CG32372 (Fig 5G-5G’’’) and CG17278 (Fig 5H-5H’’’) are not strongly affected in salm-i/salr-i discs (Fig 5G’, 5H’ and 5I’), but are reduced or absent in UAS-dad discs (Fig 5G’’ and 5H’’). Because the loss of CG32372 and CG17278 in UAS-dad discs cannot be rescued by the over-expression of Salm (Fig 5G’’’ and 5H’’’), we suggest that these genes are likely candidates for Dpp regulation independently of Salm/Salr. Indeed, CG32372 corresponds to larval translucida, a gene which expression was already shown to be regulated by Dpp [32]. We assume that genes expressed in the central domain of the wing disc and regulated by Dpp will be picked up in our microarray experiments as Sal-, because the extent of this territory is reduced in salm/salr knockdown discs.

Bottom Line: The Drosophila genes spalt major (salm) and spalt-related (salr) encode Zn-finger transcription factors regulated by the Decapentaplegic (Dpp) signalling pathway in the wing imaginal disc.We studied by in situ hybridization the expression pattern of the genes whose mRNA levels varied significantly, and uncovered a complex transcription landscape regulated by the Spalt proteins in the wing disc.Furthermore, loss-of-function phenotypic analysis of these genes indicates, for a fraction of them, a requirement for wing growth and patterning.

View Article: PubMed Central - PubMed

Affiliation: Centro de Biología Molecular Severo Ochoa, CSIC and Universidad Autónoma de Madrid, C/Nicolás Cabrera, 1. Universidad Autónoma de Madrid, Madrid, Spain.

ABSTRACT
The Drosophila genes spalt major (salm) and spalt-related (salr) encode Zn-finger transcription factors regulated by the Decapentaplegic (Dpp) signalling pathway in the wing imaginal disc. The function of these genes is required for cell survival and proliferation in the central region of the wing disc, and also for vein patterning in the lateral regions. The identification of direct Salm and Salr target genes, and the analysis of their functions, are critical steps towards understanding the genetic control of growth and patterning of the Drosophila wing imaginal disc by the Dpp pathway. To identify candidate Salm/Salr target genes, we have compared the expression profile of salm/salr knockdown wing discs with control discs in microarray experiments. We studied by in situ hybridization the expression pattern of the genes whose mRNA levels varied significantly, and uncovered a complex transcription landscape regulated by the Spalt proteins in the wing disc. Interestingly, candidate Salm/Salr targets include genes which expression is turned off and genes which expression is positively regulated by Salm/Salr. Furthermore, loss-of-function phenotypic analysis of these genes indicates, for a fraction of them, a requirement for wing growth and patterning. The identification and analysis of candidate Salm/Salr target genes opens a new avenue to reconstruct the genetic structure of the wing, linking the activity of the Dpp pathway to the development of this epithelial tissue.

No MeSH data available.


Related in: MedlinePlus