Genetic interaction between homoeotic Sex combs reduced and Regulator of bithorax (or trithorax) genes of Drosophila melanogaster

Proboscipedia (PB) is a HOX protein required for adult maxillary palp and proboscis formation. To identify domains of PB important for function, 21 pb point mutant alleles were sequenced. Twelve pb alleles had DNA sequence changes that encode an altered PB protein product. The DNA sequence changes of these 12 alleles fell into 2 categories: missense alleles that effect the PB homeodomain (HD), and nonsense or frameshift alleles that result in C-terminal truncations of the PB protein. The phenotypic analysis of the pb homeobox missense alleles suggests that the PB HD is required for maxillary palp and proboscis development and pb – Sex combs reduced (Scr) genetic interaction. The phenotypic analysis of the pb nonsense or frameshift alleles suggests that the C-terminus is an important region required for maxillary palp and proboscis development and pb–Scr genetic interaction. PB and SCR do not interact directly with one another in a co-immunoprecipitation assay and in a yeast two-hybrid analysis, which suggests the pb–Scr genetic interaction is not mediated by a direct interaction between PB and SCR.Key words: proboscipedia, Sex combs reduced, Hox genes, mutant analysis, Drosophila body plan, appendage development.

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REVERTANTS OF DOMINANT MUTATIONS ASSOCIATED WITH THE ANTENNAPEDIA GENE COMPLEX OF DROSOPHILA MELANOGASTER: CYTOLOGY AND GENETICS

Genetics ◽

10.1093/genetics/105.3.581 ◽

1983 ◽

Vol 105 (3) ◽

pp. 581-600

Author(s):

T Hazelrigg ◽

T C Kaufman

Keyword(s):

Drosophila Melanogaster ◽

Gene Complex ◽

Dominant Mutation ◽

Sex Combs Reduced ◽

X Ray ◽

Lethal Mutations ◽

Sex Combs ◽

Chromosomal Loci ◽

Chromosome Bands

ABSTRACT Using X-ray mutagenesis we have induced and recovered phenotypic revertants of four dominant mutations thought to be associated with the Antennapedia complex of Drosophila melanogaster. These include seven revertants of Antennapedia-73b (Antp73b), six of Extra Sex Combs of Wakimoto (Scxw), three of Deformed (Dfd) and one of Humeral (Hu). Fifteen of the 17 revertants are associated with chromosomal aberrations and localize Antp73b, Scxw and Hu to polytene chromosome bands 84B1,2. The Dfd lesion is apparently located in or adjacent to bands 84A4,5. Since all of the dominants are reverted by events that delete their respective chromosomal loci, we conclude that all four are the result of a gain-of-function lesions. Complementation analysis of the various revertant chromosomes has shown that Scxw and Hu are dominant allelic variants of the Antp locus. The Dfd lesion represents a dominant mutation at a locus just proximal to Antp and previously only occupied by recessive lethal mutations. Characterization of the revertants of Scxw and a comparison with the properties of the original mutation has revealed that the original lesion has effects on both the Antp and Sex Combs Reduced (Scr) loci and that these defects are in some cases separable by the reverting event.

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A functional and structural analysis of the Sex combs reduced locus of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/129.2.423 ◽

1991 ◽

Vol 129 (2) ◽

pp. 423-441 ◽

Cited By ~ 1

Author(s):

A M Pattatucci ◽

D C Otteson ◽

T C Kaufman

Keyword(s):

Drosophila Melanogaster ◽

Gene Function ◽

Molecular Mapping ◽

Genetic Locus ◽

Regulatory Region ◽

Genomic Rearrangements ◽

Fushi Tarazu ◽

Sex Combs Reduced ◽

Sex Combs ◽

Normal Head

Abstract We have undertaken a developmental genetic analysis of the homeotic gene Sex combs reduced (Scr) of Drosophila melanogaster by examining embryonic and adult phenotypes of mutations affecting Scr gene function. Molecular mapping of Scr breakpoint lesions has defined a segment of greater than 70 kb of DNA necessary for proper Scr gene function. This region is split by the fushi tarazu (ftz) gene, with lesions affecting embryonic Scr function molecularly mapping to the region proximal (5') to ftz and those exhibiting polyphasic semilethality predominantly mapping distal (3') to ftz. Gain-of-function mutations are associated with genomic rearrangements and map throughout the Scr locus. Our analysis has revealed that the Scr locus encompasses genetic elements that are responsible for functions in both the embryonic and larval to adult periods of development. From these studies, we conclude that Scr is a complex genetic locus with an extensive regulatory region that directs functions required for normal head and thoracic development in both the embryo and the adult and that the regulation of Scr during these two periods is distinct.

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Organogenesis in Drosophila melanogaster: embryonic salivary gland determination is controlled by homeotic and dorsoventral patterning genes

Development ◽

10.1242/dev.114.1.49 ◽

1992 ◽

Vol 114 (1) ◽

pp. 49-57 ◽

Cited By ~ 13

Author(s):

S. Panzer ◽

D. Weigel ◽

S.K. Beckendorf

Keyword(s):

Drosophila Melanogaster ◽

Salivary Gland ◽

Homeotic Gene ◽

Dorsoventral Patterning ◽

Sex Combs Reduced ◽

Sex Combs ◽

Positive Action ◽

Gland Morphogenesis ◽

Pattern Forming ◽

Anterior Posterior

We have investigated Drosophila salivary gland determination by examining the effects of mutations in pattern forming genes on the salivary gland primordium. We find that the anterior-posterior extent of the primordium, a placode of columnar epithelial cells derived from parasegment 2, is established by the positive action of the homeotic gene Sex combs reduced (Scr). Embryos mutant for Scr lack a detectable placode, while ectopic Scr expression leads to the formation of ectopic salivary glands. In contrast, the dorsal-ventral extent of the placode is regulated negatively. Functions dependent on the decapentaplegic product place a dorsal limit on the placode, while dorsal-dependent genes act to limit the placode ventrally. We propose a model in which these pattern forming genes act early to determine the salivary gland anlage by regulating the expression of salivary gland determining genes, which in turn control genes that are involved in salivary gland morphogenesis.

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Analysis in Drosophila melanogaster of the Interaction Between Sex Combs Reduced and Extradenticle Activity in the Determination of Tarsus and Arista Identity

Genetics ◽

10.1093/genetics/150.1.189 ◽

1998 ◽

Vol 150 (1) ◽

pp. 189-198

Author(s):

Anthony Percival-Smith ◽

Danielle J Hayden

Keyword(s):

Drosophila Melanogaster ◽

Imaginal Disc ◽

Imaginal Discs ◽

Nuclear Accumulation ◽

Sex Combs Reduced ◽

Sex Combs ◽

Disc Cells

Abstract Sex Combs Reduced (SCR) activity is proposed to be required cell nonautonomously for determination of tarsus identity, and Extradenticle (EXD) activity is required cell autonomously for determination of arista identity. Using the ability of Proboscipedia to inhibit the SCR activity required for determination of tarsus identity, we found that loss-of-EXD activity is epistatic to loss-of-SCR activity in tarsus vs. arista determination. This suggests that in the sequence leading to arista determination SCR activity is OFF while EXD activity is ON, and in the sequence leading to tarsus determination SCR activity is ON, which turns EXD activity OFF. Immunolocalization of EXD in early third-instar larval imaginal discs reveals that EXD is localized in the nuclei of antennal imaginal disc cells and localized in the cytoplasm of distal imaginal leg disc cells. We propose that EXD localized to the nucleus suppresses tarsus determination and activates arista determination. We further propose that in the mesodermal adepithelial cells of the leg imaginal discs, SCR is required for the synthesis of a tarsus-inducer that when secreted acts on the ectoderm cells inhibiting nuclear accumulation of EXD, such that tarsus determination is no longer suppressed and arista determination is no longer activated.

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DSP1, an HMG-like Protein, Is Involved in the Regulation of Homeotic Genes

Genetics ◽

10.1093/genetics/157.1.237 ◽

2001 ◽

Vol 157 (1) ◽

pp. 237-244

Author(s):

M Decoville ◽

E Giacomello ◽

M Leng ◽

D Locker

Keyword(s):

Null Allele ◽

Genetic Interaction ◽

Polycomb Group ◽

Homeotic Genes ◽

Loss Of Function ◽

Sex Combs Reduced ◽

Trithorax Group ◽

Sex Combs ◽

Normal Expression ◽

Sex Comb

Abstract The Drosophila dsp1 gene, which encodes an HMG-like protein, was originally identified in a screen for corepressors of Dorsal. Here we report that loss of dsp1 function causes homeotic transformations resembling those associated with loss of function in the homeotic genes Sex combs reduced (Scr), Ultrabithorax (Ubx), and Abdominal-B. The expression pattern of Scr is altered in dsp1 mutant imaginal discs, indicating that dsp1 is required for normal expression of this gene. Genetic interaction studies reveal that a null allele of dsp1 enhances trithorax-group gene (trx-G) mutations and partially suppresses Polycomb-group gene (Pc-G) mutations. On the contrary, overexpression of dsp1 induces an enhancement of the transformation of wings into halteres and of the extra sex comb phenotype of Pc. In addition, dsp1 male mutants exhibit a mild transformation of A4 into A5. Comparison of the chromatin structure at the Mcp locus in wild-type and dsp1 mutant embryos reveals that the 300-bp DNase I hypersensitive region is absent in a dsp1 mutant context. We propose that DSP1 protein is a chromatin remodeling factor, acting as a trx-G or a Pc-G protein depending on the considered function.

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Tarsus determination in Drosophila melanogaster

Genome ◽

10.1139/g05-021 ◽

2005 ◽

Vol 48 (4) ◽

pp. 712-721 ◽

Cited By ~ 11

Author(s):

Anthony Percival-Smith ◽

Wendy A Teft ◽

Jodi Lynn Barta

Keyword(s):

Drosophila Melanogaster ◽

Ectopic Expression ◽

Imaginal Discs ◽

Sex Combs Reduced ◽

Appendage Development ◽

Sex Combs ◽

Ectopic Overexpression ◽

A Cell ◽

Hox Protein ◽

Rule Out

Arista versus tarsus determination is well investigated in Drosophila, yet it remains unresolved whether Antennapedia (ANTP) cell autonomously or noncell autonomously determines tarsus identity and whether Sex combs reduced (SCR) is the HOX protein required for normal tarsus determination. Three observations rule out a cell autonomous role for ANTP in tarsus determination. (i) Clonal ectopic overexpression of ANTP did not repress the expression of the arista determining protein Homothorax (HTH) in early 3rd stadium antennal imaginal discs. (ii) Clonal ectopic expression of ANTP did not transform the arista to a tarsus. (iii) Ectopic overexpression of ANTP, Labial (LAB), Deformed (DFD), SCR, Ultrabithorax (UBX), Abdominal-A (ABD-A), or Abdominal-B (ABD-B), using the dppGAL4 driver, resulted in arista-to-tarsus transformations, and repressed HTH/Extradenticle (EXD) activity noncell autonomously in early 3rd stadium antennal imaginal discs. SCR may not be the HOX protein required for normal tarsus determination, because co-ectopic expression of Proboscipedia (PB) inhibited the arista-to-tarsus transformations induced by ectopic expression of DFD, SCR, ANTP, UBX, ABD-A, and ABD-B. The proposal that SCR is the HOX protein required for normal tarsus determination is dependent on SCR being the sole target of PB suppression, which is not the case. Therefore, the possibility exists that normal tarsus determination is HOX independent.Key words: appendage development, Antennapedia, proboscipedia, sex combs reduced, homothorax.

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The homeotic gene Sex combs reduced of Drosophila melanogaster is differentially regulated in the embryonic and imaginal stages of development.

Genetics ◽

10.1093/genetics/129.2.443 ◽

1991 ◽

Vol 129 (2) ◽

pp. 443-461 ◽

Cited By ~ 4

Author(s):

A M Pattatucci ◽

T C Kaufman

Keyword(s):

Gene Expression ◽

Drosophila Melanogaster ◽

Protein Localization ◽

Regulatory Region ◽

Imaginal Discs ◽

Protein Accumulation ◽

Adult Males ◽

Gain Of Function ◽

Sex Combs Reduced ◽

Sex Combs

Abstract The Sex combs reduced (Scr) locus is unique among the genes contained within the Antennapedia complex (ANT-C) of Drosophila melanogaster in that it directs functions that are required for both cephalic and thoracic development in the embryo and the adult. Antibodies raised against protein encoded by Scr were used to follow the distribution of this gene product in embryos and imaginal discs of third instar larvae. Analysis of Scr protein accumulation in embryos hemizygous for breakpoint lesions mapping throughout the locus has allowed us to determine that sequences required for establishment of the Scr embryonic pattern are contained within a region of DNA that overlaps with the identified upstream regulatory region of the segmentation gene fushi tarazu (ftz). Gain-of-function mutations in Scr result in the presence of ectopic sex comb teeth on the first tarsal segment of mesothoracic and metathoracic legs of adult males. Heterozygous combinations of gain-of-function alleles with a wild-type Scr gene exhibit no evidence of ectopic protein localization in the second and third thoracic segments of embryos. However, mesothoracic and metathoracic leg imaginal discs can be shown to accumulate ectopically expressed Scr protein, implying a differential regulation of the Scr gene during these two periods of development. Additionally, we have found that the spatial pattern of Scr gene expression in imaginal tissues involved in the development of the adult thorax is governed in part by synapsis of homologous chromosomes in this region of the ANT-C. However, those imaginal discs that arise anteriorly to the prothorax do not appear to be sensitive to this form of gene regulation. Finally, we have demonstrated that the extent of Scr expression is influenced by mutations at the Polycomb (Pc) locus but not by mutant alleles of the zeste (z) gene. Taken together, our data suggests that Scr gene expression is differentially regulated both temporally and spatially in a manner that is sensitive to the structure of the locus.

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