Disease relevance of esg

• Neuronal esg appears to act as a general seizure suppressor in the Drosophila epilepsy model as it reduces the susceptibility of several seizure-prone mutants [1].
• Ectopic expression of escargot activates the fusion process and suppresses branching throughout the tracheal system, leading to ectopic tracheal connections that resemble certain arteriovenous malformations in humans [2].

High impact information on esg

• This DNA-binding activity is essential for esg function in vivo as the strong embryonic lethal allele esgVS8 is caused by an amino acid change within the zinc finger region, leading to reduced affinity for DNA [3].
• It has therefore been suggested that the role of esg is to maintain diploidy of the imaginal cells [3].
• In larvae, esg protein expressed by the heat shock promoter can rescue the polyploid phenotype of abdominal histoblasts, demonstrating that the phenotype is attributable to a loss of esg function. esg must be expressed continuously during the larval period for efficient rescue [3].
• In some esg mutants, the abdominal histoblasts become polyploid [3].
• Ectopic expression of esg in the salivary glands inhibits endoreplication of DNA [3].

Biological context of esg

• The regulation of gene expression in germ cells by sex-specific esg enhancers is already seen in embryos [4].
• We show that esg expression in the male germline is not required for proper sex determination and spermatogenesis, as functional sperm is differentiated by mutant germ cells in wild type hosts [4].
• In esg mutant larvae, normally diploid abdominal histoblasts replicate their DNA without cell division and become similar in appearance to the polytene larval epidermal cells [5].
• MAP-kinase activation was also observed in the medial column where esg and proneural gene expression is unaffected by DER [6].
• We have named the Drosophila snail-related gene escargot (esg), and the region of sequence conservation common to all three genes the 'snailbox'. A number of Drosophila genomic DNA fragments cross-hybridize to a probe from the snailbox region suggesting that snail and escargot are members of a multigene family [7].

Anatomical context of esg

• mgm 1, the earliest sex-specific germline marker in Drosophila, reflects expression of the gene esg in male stem cells [4].
• Therefore, autonomous and non-autonomous sex-specific factors that participate in germline sex determination are already present at this early stage. esg is expressed in the male gonad, both in somatic cells and in germline stem cells [4].
• Furthermore, induction of esg in a small subset of neurons (interneurons) will reduce seizure susceptibility [1].
• Such escargot mutant tip cells failed to adhere to each other and continued to search for alternative targets by extending long filopodia [8].
• Cadherin-mediated cell adhesion and cell motility in Drosophila trachea regulated by the transcription factor Escargot [8].

Regulatory relationships of esg

• We present evidence indicating escargot positively regulates transcription of the DE-cadherin gene, shotgun [8].
• In particular, we demonstrate that the imaginal gene escargot represses Keilin's organ fate and that Keilin's organ is specified by Distal-less in conjunction with the downstream achaete-scute complex [9].

Other interactions of esg

• Here we show that a proximal gene escargot and its activator homothorax regulate proximodistal patterning in the distal domain [10].
• Proximodistal patterning in the Drosophila leg is elaborated from the circular arrangement of the proximal domain expressing escargot and homothorax, and the distal domain expressing Distal-less that are allocated during embryogenesis [10].
• The repressor function of snail is required for Drosophila gastrulation and is not replaceable by Escargot or Worniu [11].
• Among several mutations identified, neuronal escargot (esg) reduced eas seizures almost 90% [1].
• The sustained Escargot and Snail expression then activates vestigial and other target genes that are essential for wing development [12].

Analytical, diagnostic and therapeutic context of esg

• Molecular cloning and distinct developmental expression pattern of spliced forms of a novel zinc finger gene wiz in the mouse cerebellum [13].

References