echinus, required for interommatidial cell sorting and cell death in the Drosophila pupal retina, encodes a protein with homology to ubiquitin-specific proteases

Background: Programmed cell death is used to remove excess cells between ommatidia in the Drosophila pupal retina. This death is required to establish the crystalline, hexagonal packing of ommatidia that characterizes the adult fly eye. In previously described echinus mutants, interommatidial cell sorting, which precedes cell death, occurred relatively normally. Interommatidial cell death was partially suppressed, resulting in adult eyes that contained excess pigment cells, and in which ommatidia were mildly disordered. These results have suggested that echinus functions in the pupal retina primarily to promote interommatidial cell death. Results: We generated a number of new echinus alleles, some of which are likely null mutants. Analysis of these alleles provides evidence that echinus has roles in cell sorting as well as cell death. echinus encodes a protein with homology to ubiquitin-specific proteases, which cleave ubiquitin-conjugated proteins at the ubiquitin C-terminus. The echinus locus encodes multiple splice forms, including two proteins that lack residues thought to be critical for deubiquitination activity. Surprisingly, ubiquitous expression in the eye of versions of Echinus that lack residues critical for ubiquitin specific protease activity, as well as a version predicted to be functional, rescue the echinus loss-of-function phenotype. Finally, genetic interactions were not detected between echinus loss and gain-of-function and a number of known apoptotic regulators. These include Notch, EGFR, the caspases Dronc, Drice, Dcp-1, Dream, the caspase activators, Rpr, Hid, and Grim, the caspase inhibitor DIAP1, and Lozenge or Klumpfuss. Conclusions: The echinus locus encodes multiple splice forms of a protein with homology to ubiquitin-specific proteases, but protease activity is unlikely to be required for echinus function, at least when echinus is overexpressed. Characterization of likely echinus null alleles and genetic interactions suggests that echinus acts at a novel point(s) to regulate interommatidial cell sorting and/or cell death in the fly eye

Identification of echinus and characterization of its role in Drosophila eye development

The precise structure of the adult Drosophila eye results from a coordinated process of cell sorting, differentiation and selective cell death in the retinal epithelium. Mutations in the gene echinus cause supernumerary pigment cells due to insufficient cell death. This study reports the identification of echinus and the characterization of its role in Drosophila retinal development. Using a combination of deletion mapping, gene expression analysis and genomic sequencing, echinus was cloned and several alleles were sequenced. echinus encodes a ~180kDa protein containing an ubiquitin hydrolase domain at its N-terminus and a polyglutamine tract at its C-terminus. echinus is expressed in the retina during pupal development and mutants of echinus have decreased levels of apoptosis during several stages of retinal development. Defects in the cell sorting process that precedes cell death are also observed in echinus loss-of-function mutants and echinus overexpression can cause defects in ommatidial rotation and the morphology of cone cells. echinus is a positive regulator of DE-cadherin and Enabled accumulation in adherens junctions of retinal epithelial cells. Genetic interactions were observed between echinus and the genes wingless, enabled and expanded. An immunofluorescence assay in Drosophila S2 cell cultured demonstrated that Echinus localizes to intracellular vesicles that do not appear to be endocytic in nature, and the C-terminal region of Echinus was shown to be necessary for this association. A protein interaction screen using an immunoprecipitation and mass spectrometry approach identified interactions between Echinus and the vesicle coat protein Clathrin, the scaffolding protein RACK1 and the casein kinase I epsilon (Dco). Co-immunoprecipitation additionally identified an interaction between Echinus and Enabled. This work has revealed echinus to be an important regulator of cell sorting and adherens junction formation in the developing retina and has identified multiple interactions between echinus and enabled, a regulator of the actin cytoskeleton.Medicine, Faculty ofMedical Genetics, Department ofGraduat

Internet Contig Explorer (iCE)—A Tool for Visualizing Clone Fingerprint Maps

Fingerprinted clone physical maps have proven useful in various applications, supporting both whole-genome and region-specific DNA sequencing as well as gene cloning studies. Fingerprint maps have been generated for several genomes, including those of human, mouse, rat, the nematodes Caenorhabditis elegans and Caenorhabditis briggsae, Arabidopsis thaliana and rice. Fingerprint maps of other genomes, including those of fungi, bacteria, poplar, and the cow, are being generated. The increasing use of fingerprint maps in genomic research has spawned a need in the research community for intuitive computer tools that facilitate viewing of the maps and the underlying fingerprint data. In this report we describe a new Java-based application called iCE (Internet Contig Explorer) that has been designed to provide views of fingerprint maps and associated data. Users can search for and display individual clones, contigs, clone fingerprints, clone insert sizes and markers. Users can also load into the software lists of particular clones of interest and view their fingerprints. iCE is being used at our Genome Centre to offer up to the research community views of the mouse, rat, bovine, C. briggsae, and several fungal genome bacterial artificial chromosome (BAC) fingerprint maps we have either completed or are currently constructing. We are also using iCE as part of the Rat Genome Sequencing Project to manage our provision of rat BAC clones for sequencing at the Human Genome Sequencing Center at the Baylor College of Medicine

Real-World Clinical Outcomes for Patients with <i>EGFR</i> and <i>HER2</i> Exon 20 Insertion-Mutated Non-Small-Cell Lung Cancer

(1) Background: Exon 20 insertion mutations (ex20ins) in EGFR and HER2 are uncommon driver mutations in non-small-cell lung cancer (NSCLC), with a poor prognosis and few targeted therapy options, and there are limited real-world data. Here, we report the clinicopathologic features and outcomes for patients with ex20ins NSCLC across British Columbia, Canada. (2) Methods: NSCLC patients with ex20ins in EGFR or HER2 were identified via tumour testing between 1 January 2016 and 31 December 2021 (n = 7233). Data were collected by chart review. Survival analyses were performed using the Kaplan–Meier method using the log-rank test. (3) Results: A total of 131 patients were identified. The median age was 66. Thirty-three percent of patients had brain metastases. For the EGFR cohort, the median OS was 18.6 months for patients who received any systemic therapy (ST) vs. 2.6 months for patients who did not (p p = 0.463). The median first-line PFS was 4.1 vs. 7.4 months for patients treated with a TKI vs. other ST (p = 0.744). For the HER2 cohort, the median OS was 9.0 months for patients who received any ST vs. 4.9 months for patients who did not (p = 0.015). The median OS was 23.0 months for patients treated with an ex20ins TKI vs. 5.6 months for patients who were not (p = 0.019). The median first-line PFS was 5.4 vs. 2.1 months for patients treated with a TKI vs. other ST (p = 0.343). (4) Conclusions: Overall survival was significantly longer among ex20ins patients who received any systemic therapy vs. those who did not. Overall survival was significantly better among HER2 ex20ins patients who received ex20ins-specific TKIs

Genetic interactions between and known or potential regulators of cell death in the eye

<p><b>Copyright information:</b></p><p>Taken from ", required for interommatidial cell sorting and cell death in the pupal retina, encodes a protein with homology to ubiquitin-specific proteases"</p><p>http://www.biomedcentral.com/1471-213X/7/82</p><p>BMC Developmental Biology 2007;7():82-82.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1950886.</p><p></p> To the right is a schematic depicting known or suggested interactions between death regulators in the fly. The question mark separating Debcl/Buffy from Ark indicates the uncertainy as to the roles these proteins play in regulating Ark activation or activity. GMR-driven transgenes of the indicated genotype were introduced into the background, or into a wildtype background in the presence of GMR-ec-SF1. For each death regulator tested, similar phenotypes were observed in the presence of GMR-ec-SF2 (data not shown)

Flies with mutations in CG2904 have rough eyes, defects in IOC sorting, an increase in IOC number (A-F) SEM views of adult fly eyes of various genotypes

<p><b>Copyright information:</b></p><p>Taken from ", required for interommatidial cell sorting and cell death in the pupal retina, encodes a protein with homology to ubiquitin-specific proteases"</p><p>http://www.biomedcentral.com/1471-213X/7/82</p><p>BMC Developmental Biology 2007;7():82-82.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1950886.</p><p></p> (G-O) Pupal retinas of various genotypes stained with anti-Dlg. (A, G) Wildtype flies have regularly spaced ommatidia and an invariant number of IOCs. Cell types indicated are bristle (B), 2°, 3°, and asterisk represent extra IOCs. (B,H) flies obtained from the Bloomington Stock center have rough eyes and a modest number of extra 2° and 3° pigment cells. (C,I) GMR-driven RNAi of CG2904 results in flies with rough eyes and a large increase in IOCs, with many stacked side-by-side in parallel rows. (D,J) Flies homozygous for a deletion in CG2904, , have rough eyes, a large increase in IOCs, with many cells stacked side-by-side in parallel rows. (E,K) GMR-dependent expression of ec-SF1 has no effect on the adult eye and does not cause any excess death of IOCs. (F,L) Expression of GMR-ec-SF1 restores normal levels of IOC death to flies. (M,N) Pupal eyes from two independent stocks of outcrossed for 5 generations. There are increased numbers of IOCs as compared with the original stock, and many extra cells are aligned side-by-side in parallel rows. (O) Pupal eyes from flies have a modest increase in IOC number and few defects in cell sorting

Echinus does not require deubiquitinating activity to promote normal IOC death

<p><b>Copyright information:</b></p><p>Taken from ", required for interommatidial cell sorting and cell death in the pupal retina, encodes a protein with homology to ubiquitin-specific proteases"</p><p>http://www.biomedcentral.com/1471-213X/7/82</p><p>BMC Developmental Biology 2007;7():82-82.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1950886.</p><p></p> (A-D) SEMs of adult eyes of various genotypes. (E-H) Pupal retinas of various genotypes stained with anti-Dlg. (A,E) GMR-driven expression of a microRNA targeting ec-SF1 results in an echinus phenotype. (B,F) eyes. (C,G) Eyes of genotype ; GMR-ec-SF2/+. (D,H) Eyes of genotype ; GMR-ec-SF3/+. Expression of versions of Echinus that lack essential USP catalytic residues rescues the phenotype

Physical Maps for Genome Analysis of Serotype A and D Strains of the Fungal Pathogen Cryptococcus neoformans

The basidiomycete fungus Cryptococcus neoformans is an important opportunistic pathogen of humans that poses a significant threat to immunocompromised individuals. Isolates of C. neoformans are classified into serotypes (A, B, C, D, and AD) based on antigenic differences in the polysaccharide capsule that surrounds the fungal cells. Genomic and EST sequencing projects are underway for the serotype D strain JEC21 and the serotype A strain H99. As part of a genomics program for C. neoformans, we have constructed fingerprinted bacterial artificial chromosome (BAC) clone physical maps for strains H99 and JEC21 to support the genomic sequencing efforts and to provide an initial comparison of the two genomes. The BAC clones represented an estimated 10-fold redundant coverage of the genomes of each serotype and allowed the assembly of 20 contigs each for H99 and JEC21. We found that the genomes of the two strains are sufficiently distinct to prevent coassembly of the two maps when combined fingerprint data are used to construct contigs. Hybridization experiments placed 82 markers on the JEC21 map and 102 markers on the H99 map, enabling contigs to be linked with specific chromosomes identified by electrophoretic karyotyping. These markers revealed both extensive similarity in gene order (conservation of synteny) between JEC21 and H99 as well as examples of chromosomal rearrangements including inversions and translocations. Sequencing reads were generated from the ends of the BAC clones to allow correlation of genomic shotgun sequence data with physical map contigs. The BAC maps therefore represent a valuable resource for the generation, assembly, and finishing of the genomic sequence of both JEC21 and H99. The physical maps also serve as a link between map-based and sequence-based data, providing a powerful resource for continued genomic studies. [This paper is dedicated to the memory of Michael Smith, Founding Director of the Biotechnology Laboratory and the BC Cancer Agency Genome Sciences Centre. Supplemental material is available online at http://www.genome.org.

A BAC-based physical map of the Drosophila buzzatii genome

Large-insert genomic libraries facilitate cloning of large genomic regions, allow the construction of clone-based physical maps and provide useful resources for sequencing entire genomes. Drosophila buzzatii is a representative species of the repleta group in the Drosophila subgenus, which is being widely used as a model in studies of genome evolution, ecological adaptation and speciation. We constructed a Bacterial Artificial Chromosome (BAC) genomic library of D. buzzatii using the shuttle vector pTARBAC2.1. The library comprises 18,353 clones with an average insert size of 152 kb and a ~;18X expected representation of the D. buzzatii euchromatic genome. We screened the entire library with six euchromatic gene probes and estimated the actual genome representation to be ~;23X. In addition, we fingerprinted by restriction digestion and agarose gel electrophoresis a sample of 9,555 clones, and assembled them using FingerPrinted Contigs (FPC) software and manual editing into 345 contigs (mean of 26 clones per contig) and 670 singletons. Finally, we anchored 181 large contigs (containing 7,788 clones) to the D. buzzatii salivary gland polytene chromosomes by in situ hybridization of 427 representative clones. The BAC library and a database with all the information regarding the high coverage BAC-based physical map described in this paper are available to the research community

A BAC-based physical map of the Drosophila buzzatii genome

Large-insert genomic libraries facilitate cloning of large genomic regions, allow the construction of clone-based physical maps and provide useful resources for sequencing entire genomes. Drosophila buzzatii is a representative species of the repleta group in the Drosophila subgenus, which is being widely used as a model in studies of genome evolution, ecological adaptation and speciation. We constructed a Bacterial Artificial Chromosome (BAC) genomic library of D. buzzatii using the shuttle vector pTARBAC2.1. The library comprises 18,353 clones with an average insert size of 152 kb and a ~;18X expected representation of the D. buzzatii euchromatic genome. We screened the entire library with six euchromatic gene probes and estimated the actual genome representation to be ~;23X. In addition, we fingerprinted by restriction digestion and agarose gel electrophoresis a sample of 9,555 clones, and assembled them using FingerPrinted Contigs (FPC) software and manual editing into 345 contigs (mean of 26 clones per contig) and 670 singletons. Finally, we anchored 181 large contigs (containing 7,788 clones) to the D. buzzatii salivary gland polytene chromosomes by in situ hybridization of 427 representative clones. The BAC library and a database with all the information regarding the high coverage BAC-based physical map described in this paper are available to the research community