The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
L. S. Shashidhara - One of the best experts on this subject based on the ideXlab platform.
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The Drosophila Hox gene Ultrabithorax controls appendage shape by regulating extracellular matrix dynamics
Development (Cambridge England), 2018Co-Authors: José Manuel De Las Heras, Celia García-cortés, David Foronda, José Carlos Pastor-pareja, L. S. Shashidhara, Ernesto Sánchez-herreroAbstract:Although the specific form of an organ is frequently important for its function, the mechanisms underlying organ shape are largely unknown. In Drosophila, the wings and halteres, homologous appendages of the second and third thoracic segments, respectively, bear different forms: wings are flat, whereas halteres are globular, and yet both characteristic shapes are essential for a normal flight. The Hox gene Ultrabithorax (Ubx) governs the difference between wing and haltere development, but how Ubx function in the appendages prevents or allows flat or globular shapes is unknown. Here, we show that Ubx downregulates Matrix metalloproteinase 1 (Mmp1) expression in the haltere pouch at early pupal stage, which in turn prevents the rapid clearance of Collagen IV compared with the wing disc. This difference is instrumental in determining cell shape changes, expansion of the disc and apposition of dorsal and ventral layers, all of these phenotypic traits being characteristic of wing pouch development. Our results suggest that Ubx regulates organ shape by controlling Mmp1 expression, and the extent and timing of extracellular matrix degradation.
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Quantification of Mmp1 and Vkg.pdf
2018Co-Authors: José Manuel De Las Heras, Celia García-cortés, David Foronda, José Carlos Pastor-pareja, L. S. Shashidhara, Ernesto Sánchez-herreroAbstract:Macros for the quantification of Metalloproteinase 1 and Viking in wing and haltere discs of wildtype, Haltere mimic and Ultrabithorax RNAi Drosophila prepupae
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critical role for fat hippo and iis akt pathways downstream of ultrabithorax during haltere specification in drosophila
Mechanisms of Development, 2015Co-Authors: L. S. Shashidhara, Ernesto Sanchezherrero, Savita SinghAbstract:In Drosophila, differential development of wing and haltere, which differ in cell size, number and morphology, is dependent on the function of Hox gene Ultrabithorax (Ubx). Here we report our studies on Ubx-mediated regulation of the Fat/Hippo and IIS/dAkt pathways, which control cell number and cell size during development. Over-expression of Yki or down regulation of negative components of the Fat/Hippo pathway, such as expanded, caused considerable increase in haltere size, mainly due to increase in cell number. These phenotypes were also associated with the activation of Akt pathways in developing haltere. Although activation of Akt alone did not affect the cell size or the organ size, we observed dramatic increase in haltere size when Akt was activated in the background where expanded is down regulated. This was associated with the increase in both cell size and cell number. The organ appeared flatter than wildtype haltere and the trichome morphology and spacing resembled that of wing suggesting homeotic transformations. Thus, our results suggest a link between cellular growth and pattern formation and the final differentiated state of the organ.
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Negative regulation of Ultrabithorax expression by engrailed is required for proper specification of wing development in Drosophila melanogaster
2015Co-Authors: B. Starling, L. S. ShashidharaAbstract:In both vertebrates and invertebrates, homeotic selector genes confer morphological differences along the antero-posterior axis. However, insect wing development is independent of all homeotic gene functions, reflecting the ground plan of an ancestral pterygote, which bore wings on all segments. Dipteran insects such as Drosophila are characterized by a pair of wings in the mesothoracic segment. In all other segments, wing development is essentially repressed by different homeotic genes, although in the metathorax they are modi®ed into a pair of halteres. This necessitates that during development all homeotic genes are to be maintained in a repressed state in wing imaginal discs. In this report we show that (i) the function of the segment polarity gene engrailed (en) is critical to keep the homeotic selector gene Ultrabithorax (Ubx) repressed in wing imaginal discs, (ii) normal levels of En in the posterior compartment of haltere discs, however, are not enough to completely repress Ubx, and (iii) the repression of Ubx by en is independent of Hedgehog signalling through which the long-range signalling of en is mediated during wing development. Finally we provide evidence for a possible mechanism by which en represses Ubx. On the basis of these results we propose that en has acquired two independent functions during the evolution of dorsal appendages. In addition to its well-known function of conferring posterior fate and inducing long-range signalling to pattern the developing appendages, it maintains wing fate by keeping Ubx repressed. [Emerald B. S. and Shashidhara L. S. 2000 Negative regulation of Ultrabithorax expression by engrailed is required for the proper speci®cation of wing development in Drosophila melanogaster. J. Genet. 79, 61±70
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Critical role for Fat/Hippo and IIS/Akt pathways downstream of Ultrabithorax during haltere specification in Drosophila.
Mechanisms of Development, 2015Co-Authors: Savita Singh, Ernesto Sánchez-herrero, L. S. ShashidharaAbstract:In Drosophila, differential development of wing and haltere, which differ in cell size, number and morphology, is dependent on the function of Hox gene Ultrabithorax (Ubx). Here we report our studies on Ubx-mediated regulation of the Fat/Hippo and IIS/dAkt pathways, which control cell number and cell size during development. Over-expression of Yki or down regulation of negative components of the Fat/Hippo pathway, such as expanded, caused considerable increase in haltere size, mainly due to increase in cell number. These phenotypes were also associated with the activation of Akt pathways in developing haltere. Although activation of Akt alone did not affect the cell size or the organ size, we observed dramatic increase in haltere size when Akt was activated in the background where expanded is down regulated. This was associated with the increase in both cell size and cell number. The organ appeared flatter than wildtype haltere and the trichome morphology and spacing resembled that of wing suggesting homeotic transformations. Thus, our results suggest a link between cellular growth and pattern formation and the final differentiated state of the organ.
Ernesto Sánchez-herrero - One of the best experts on this subject based on the ideXlab platform.
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The Drosophila Hox gene Ultrabithorax controls appendage shape by regulating extracellular matrix dynamics
Development (Cambridge England), 2018Co-Authors: José Manuel De Las Heras, Celia García-cortés, David Foronda, José Carlos Pastor-pareja, L. S. Shashidhara, Ernesto Sánchez-herreroAbstract:Although the specific form of an organ is frequently important for its function, the mechanisms underlying organ shape are largely unknown. In Drosophila, the wings and halteres, homologous appendages of the second and third thoracic segments, respectively, bear different forms: wings are flat, whereas halteres are globular, and yet both characteristic shapes are essential for a normal flight. The Hox gene Ultrabithorax (Ubx) governs the difference between wing and haltere development, but how Ubx function in the appendages prevents or allows flat or globular shapes is unknown. Here, we show that Ubx downregulates Matrix metalloproteinase 1 (Mmp1) expression in the haltere pouch at early pupal stage, which in turn prevents the rapid clearance of Collagen IV compared with the wing disc. This difference is instrumental in determining cell shape changes, expansion of the disc and apposition of dorsal and ventral layers, all of these phenotypic traits being characteristic of wing pouch development. Our results suggest that Ubx regulates organ shape by controlling Mmp1 expression, and the extent and timing of extracellular matrix degradation.
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Quantification of Mmp1 and Vkg.pdf
2018Co-Authors: José Manuel De Las Heras, Celia García-cortés, David Foronda, José Carlos Pastor-pareja, L. S. Shashidhara, Ernesto Sánchez-herreroAbstract:Macros for the quantification of Metalloproteinase 1 and Viking in wing and haltere discs of wildtype, Haltere mimic and Ultrabithorax RNAi Drosophila prepupae
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Critical role for Fat/Hippo and IIS/Akt pathways downstream of Ultrabithorax during haltere specification in Drosophila.
Mechanisms of Development, 2015Co-Authors: Savita Singh, Ernesto Sánchez-herrero, L. S. ShashidharaAbstract:In Drosophila, differential development of wing and haltere, which differ in cell size, number and morphology, is dependent on the function of Hox gene Ultrabithorax (Ubx). Here we report our studies on Ubx-mediated regulation of the Fat/Hippo and IIS/dAkt pathways, which control cell number and cell size during development. Over-expression of Yki or down regulation of negative components of the Fat/Hippo pathway, such as expanded, caused considerable increase in haltere size, mainly due to increase in cell number. These phenotypes were also associated with the activation of Akt pathways in developing haltere. Although activation of Akt alone did not affect the cell size or the organ size, we observed dramatic increase in haltere size when Akt was activated in the background where expanded is down regulated. This was associated with the increase in both cell size and cell number. The organ appeared flatter than wildtype haltere and the trichome morphology and spacing resembled that of wing suggesting homeotic transformations. Thus, our results suggest a link between cellular growth and pattern formation and the final differentiated state of the organ.
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The ultrabithorax Hox gene of Drosophila controls haltere size by regulating the Dpp pathway.
Development (Cambridge England), 2006Co-Authors: Luis F. De ,navas, Daniel L. Garaulet, Ernesto Sánchez-herreroAbstract:The halteres and wings of Drosophila are homologous thoracic appendages, which share common positional information provided by signaling pathways. The activity in the haltere discs of the Ultrabithorax ( Ubx ) Hox gene establishes the differences between these structures, their different size being an obvious one. We show here that Ubx regulates the activity of the Decapentaplegic (Dpp) signaling pathway at different levels, and that this regulation is instrumental in establishing the size difference. Ubx downregulates dpp transcription and reduces Dpp diffusion by repressing the expression of master of thick veins and division abnormally delayed and by increasing the levels of thick veins , one of the Dpp receptors. Our results suggest that modulation in Dpp expression and spread accounts, in part, for the different size of halteres and wings.
Ernesto Sanchezherrero - One of the best experts on this subject based on the ideXlab platform.
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critical role for fat hippo and iis akt pathways downstream of ultrabithorax during haltere specification in drosophila
Mechanisms of Development, 2015Co-Authors: L. S. Shashidhara, Ernesto Sanchezherrero, Savita SinghAbstract:In Drosophila, differential development of wing and haltere, which differ in cell size, number and morphology, is dependent on the function of Hox gene Ultrabithorax (Ubx). Here we report our studies on Ubx-mediated regulation of the Fat/Hippo and IIS/dAkt pathways, which control cell number and cell size during development. Over-expression of Yki or down regulation of negative components of the Fat/Hippo pathway, such as expanded, caused considerable increase in haltere size, mainly due to increase in cell number. These phenotypes were also associated with the activation of Akt pathways in developing haltere. Although activation of Akt alone did not affect the cell size or the organ size, we observed dramatic increase in haltere size when Akt was activated in the background where expanded is down regulated. This was associated with the increase in both cell size and cell number. The organ appeared flatter than wildtype haltere and the trichome morphology and spacing resembled that of wing suggesting homeotic transformations. Thus, our results suggest a link between cellular growth and pattern formation and the final differentiated state of the organ.
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integration of rna processing and expression level control modulates the function of the drosophila hox gene ultrabithorax during adult development
Development, 2011Co-Authors: Luis F. De ,navas, Michael Akam, Hilary Reed, Rosa Barrio, Claudio R Alonso, Ernesto SanchezherreroAbstract:Although most metazoan genes undergo alternative splicing, the functional relevance of the majority of alternative splicing products is still unknown. Here we explore this problem in the Drosophila Hox gene Ultrabithorax (Ubx). Ubx produces a family of six protein isoforms through alternative splicing. To investigate the functional specificity of the Ubx isoforms, we studied their role during the formation of the Drosophila halteres, small dorsal appendages that are essential for normal flight. Our work shows that isoform Ia, which is encoded by all Ubx exons, is more efficient than isoform IVa, which lacks the amino acids coded by two small exons, in controlling haltere development and regulating Ubx downstream targets. However, our experiments also demonstrate that the functional differences among the Ubx isoforms can be compensated for by increasing the expression levels of the less efficient form. The analysis of the DNA-binding profiles of Ubx isoforms to a natural Ubx target, spalt, shows no major differences in isoform DNA-binding activities, suggesting that alternative splicing might primarily affect the regulatory capacity of the isoforms rather than their DNA-binding patterns. Our results suggest that to obtain distinct functional outputs during normal development genes must integrate the generation of qualitative differences by alternative splicing to quantitative processes affecting isoform protein expression levels.
Ramakrishnan Kannan - One of the best experts on this subject based on the ideXlab platform.
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negative regulation of egfr ras pathway by ultrabithorax during haltere development in drosophila
Developmental Biology, 2006Co-Authors: S. K. Pallavi, Ramakrishnan Kannan, L. S. ShashidharaAbstract:In Drosophila, wings and halteres are the dorsal appendages of the second and third thoracic segments, respectively. In the third thoracic segment, homeotic selector gene Ultrabithorax (Ubx) suppresses wing development to mediate haltere development (E.B. Lewis, 1978. A gene complex controlling segmentation in Drosophila. Nature 276, 565-570). Halteres lack stout sensory bristles of the wing margin and veins that reticulate the wing blade. Furthermore, wing and haltere epithelia differ in the size, shape, spacing and number of cuticular hairs. The differential development of wing and haltere, thus, constitutes a good genetic system to study cell fate determination. Here, we report that down-regulation of Egfr/Ras pathway is critical for haltere fate specification: over-expression of positive components of this pathway causes significant haltere-to-wing transformations. RNA in situ, immunohistochemistry, and epistasis genetic experiments suggest that Ubx negatively regulates the expression of the ligand vein as well as the receptor Egf-r to down-regulate the signaling pathway. Electromobility shift assays further suggest that Egf-r is a potential direct target of Ubx. These results and other recent findings suggest that homeotic genes may regulate cell fate determination by directly regulating few steps at the top of the hierarchy of selected signal transduction pathways.
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Negative regulation of Egfr/Ras pathway by Ultrabithorax during haltere development in Drosophila
Developmental biology, 2006Co-Authors: S. K. Pallavi, Ramakrishnan Kannan, L. S. ShashidharaAbstract:In Drosophila, wings and halteres are the dorsal appendages of the second and third thoracic segments, respectively. In the third thoracic segment, homeotic selector gene Ultrabithorax (Ubx) suppresses wing development to mediate haltere development (E.B. Lewis, 1978. A gene complex controlling segmentation in Drosophila. Nature 276, 565-570). Halteres lack stout sensory bristles of the wing margin and veins that reticulate the wing blade. Furthermore, wing and haltere epithelia differ in the size, shape, spacing and number of cuticular hairs. The differential development of wing and haltere, thus, constitutes a good genetic system to study cell fate determination. Here, we report that down-regulation of Egfr/Ras pathway is critical for haltere fate specification: over-expression of positive components of this pathway causes significant haltere-to-wing transformations. RNA in situ, immunohistochemistry, and epistasis genetic experiments suggest that Ubx negatively regulates the expression of the ligand vein as well as the receptor Egf-r to down-regulate the signaling pathway. Electromobility shift assays further suggest that Egf-r is a potential direct target of Ubx. These results and other recent findings suggest that homeotic genes may regulate cell fate determination by directly regulating few steps at the top of the hierarchy of selected signal transduction pathways.
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Modulation of AP and DV signaling pathways by the homeotic gene Ultrabithorax during haltere development in Drosophila.
Developmental biology, 2006Co-Authors: Prasad Mohit, Kalpana Makhijani, M.b. Madhavi, V. Bharathi, Ashish Lal, Gururaj Sirdesai, V. Ram Reddy, Palaparthi Ramesh, Ramakrishnan Kannan, Jyotsna DhawanAbstract:Suppression of wing fate and specification of haltere fate in Drosophila by the homeotic gene Ultrabithorax is a classical example of Hox regulation of serial homology (Lewis, E.B. 1978. Nature 276, 565-570) and has served as a paradigm for understanding homeotic gene function. We have used DNA microarray analyses to identify potential targets of Ultrabithorax function during haltere specification. Expression patterns of 18 validated target genes and functional analyses of a subset of these genes suggest that down-regulation of both anterior-posterior and dorso-ventral signaling is critical for haltere fate specification. This is further confirmed by the observation that combined over-expression of Decapentaplegic and Vestigial is sufficient to override the effect of Ubx and cause dramatic haltere-to-wing transformations. Our results also demonstrate that analysis of the differential development of wing and haltere is a good assay system to identify novel regulators of key signaling pathways.
Savita Singh - One of the best experts on this subject based on the ideXlab platform.
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critical role for fat hippo and iis akt pathways downstream of ultrabithorax during haltere specification in drosophila
Mechanisms of Development, 2015Co-Authors: L. S. Shashidhara, Ernesto Sanchezherrero, Savita SinghAbstract:In Drosophila, differential development of wing and haltere, which differ in cell size, number and morphology, is dependent on the function of Hox gene Ultrabithorax (Ubx). Here we report our studies on Ubx-mediated regulation of the Fat/Hippo and IIS/dAkt pathways, which control cell number and cell size during development. Over-expression of Yki or down regulation of negative components of the Fat/Hippo pathway, such as expanded, caused considerable increase in haltere size, mainly due to increase in cell number. These phenotypes were also associated with the activation of Akt pathways in developing haltere. Although activation of Akt alone did not affect the cell size or the organ size, we observed dramatic increase in haltere size when Akt was activated in the background where expanded is down regulated. This was associated with the increase in both cell size and cell number. The organ appeared flatter than wildtype haltere and the trichome morphology and spacing resembled that of wing suggesting homeotic transformations. Thus, our results suggest a link between cellular growth and pattern formation and the final differentiated state of the organ.
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Critical role for Fat/Hippo and IIS/Akt pathways downstream of Ultrabithorax during haltere specification in Drosophila.
Mechanisms of Development, 2015Co-Authors: Savita Singh, Ernesto Sánchez-herrero, L. S. ShashidharaAbstract:In Drosophila, differential development of wing and haltere, which differ in cell size, number and morphology, is dependent on the function of Hox gene Ultrabithorax (Ubx). Here we report our studies on Ubx-mediated regulation of the Fat/Hippo and IIS/dAkt pathways, which control cell number and cell size during development. Over-expression of Yki or down regulation of negative components of the Fat/Hippo pathway, such as expanded, caused considerable increase in haltere size, mainly due to increase in cell number. These phenotypes were also associated with the activation of Akt pathways in developing haltere. Although activation of Akt alone did not affect the cell size or the organ size, we observed dramatic increase in haltere size when Akt was activated in the background where expanded is down regulated. This was associated with the increase in both cell size and cell number. The organ appeared flatter than wildtype haltere and the trichome morphology and spacing resembled that of wing suggesting homeotic transformations. Thus, our results suggest a link between cellular growth and pattern formation and the final differentiated state of the organ.
