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)

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

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

Caspase Activity Is Required for Spermatid Individualization

<div><p>(A–C) Testis of different genotypes were visualized with antibodies specific for activated Drice (green). (A) Wild-type testis. Active DRICE is present in multiple elongated cysts. Cystic bulges (cb) and waste bags (wb) are indicated by arrows. (B and C) Testes from β2tub-DIAP1 and β2tub-p35 males, respectively. Active DRICE is present in elongated cysts, but cystic bulges and waste bags are reduced in number and size.</p> <p>(D–F) Phalloidin-stained investment cones from testes of different genotypes (red). Spermatid axonemes in (D)–(F) are highlighted by the AXO49 antibody, which recognizes polyglycylated β2tub (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020015#pbio-0020015-Bressac1" target="_blank">Bressac et al. 1995</a>) (blue). (D) In wild-type testes, investment cones move as a coordinated group. (E and F) Coordinated investment cone movement is disrupted in cysts from β2tub-DIAP1 and β2tub-p35 males, respectively.</p> <p>(G–L) EM sections of elongated cysts of different genotypes. (G) A cyst from a wild-type male that has undergone individualization. The boxed region is shown at higher magnification in (J), along with the locations of the major mitochondrial derivative (mj), minor mitochondrial derivative (mi), and axoneme (ax). A single spermatid unit is outlined with a dashed line. (H and I) In cysts from β2tub-DIAP1 and β2tub-p35 males, respectively, many spermatid units are present in a common cytoplasm that contains organelles, often including an enlarged minor mitochondrial derivative. Boxed regions of β2tub-DIAP1 and β2tub-p35 cysts shown in (H) and (I) are shown at higher magnification in (K) and (L), respectively. Several examples of multiple spermatids present in a common cytoplasm are outlined by the dashed line in (K) and (L). Scale bar for EM micrographs = 1 μm.</p></div

ARK and DRONC Are Required for Spermatid Individualization

<div><p>(A and C) Testis from β2tub-Ark-RNAi and β2tub-Dn-DRONC males, respectively. Active DRICE-positive cysts are present, but cystic bulges and waste bags are largely absent.</p> <p>(B and D) Investment cone movements in testis from β2tub-Ark-RNAi and β2tub-Dn-DRONC, respectively, are uncoordinated.</p> <p>(E, G, and H) EM images of an elongated cyst from a β2tub-Ark-RNAi male. Some individualization failures are observed (E, G, and H), two of which are highlighted by the dashed lines in (G) and (H). In addition, many spermatids that have apparently undergone individualization still contain large amounts of excess cytoplasm (E and G).</p> <p>(F) EM image of a cyst from a β2ub-Dn-DRONC male. A large region in which individualization did not occur is outlined.</p> <p>(I) Western blot from wild-type (Wt) and β2tub-Ark-RNAi (DArki) testis probed with anti-ARK and anti-DRICE antibodies. ARK, but not DRICE, levels are greatly reduced in β2tub-Ark-RNAi testis.</p></div

DRONC Activation Occurs in Association with Individualization Complexes and Is ARK-Dependent

<div><p>(A and B) Wild-type testis stained for active DRICE (green), phalloidin-stained filamentous actin (red), and TOTO-3-stained DNA (blue). (A) Active DRICE is present throughout the length of cysts undergoing individualization. (B) Higher magnification of the testis in (A). The arrowhead points to a cyst in which the individualization complex has assembled around the spermatid nuclei, but DRICE activation has not occurred. The arrow points to a neighboring cyst in which the individualization complex has just begun to move away from the spermatid nuclei. Active DRICE is now present throughout the length of this cyst, indicating that DRICE activation within a cyst occurs rapidly and globally.</p> <p>(C) Active DRONC (green) is initially present in a punctate pattern, apical to the individualization complex (red) at the base of the testis (arrowheads). The individualization complex then moves through the region containing active DRONC (arrow).</p> <p>(D) Subsequently, active DRONC is found associated with the trailing edge of the individualization complex as it moves apical within the cyst. A higher magnification view of active DRONC staining in the left-most cyst is shown in the inset.</p> <p>(E and F) Active DRONC is eliminated in cysts from β2tub-Ark-RNAi and β2tub-Dn-DRONC testis, respectively.</p></div

HID, dFADD, and DREDD Participate in Individualization

<div><p>(A) HID protein (green) is concentrated in the region of the cystic bulge, which is marked by the presence of the phalloidin-stained individualization complex (red).</p> <p>(B) HID immunoreactivity is absent in testis from <i>hid ⁰⁵⁰¹⁴/H99</i> flies.</p> <p>(C) Active DRONC (green) is associated with the trailing edge of the individualization complex in a wild-type cyst.</p> <p>(D) Active DRONC is absent from the individualization complex in cysts from <i>hid ⁰⁵⁰¹⁴/H99</i> males.</p> <p>(E) EM section from <i>hid ⁰⁵⁰¹⁴/H99</i> testis. Essentially all spermatids have failed to individualize.</p> <p>(F) Higher magnification view of boxed area in (E). Multiple spermatid units sharing a common cytoplasm are outlined by the dashed line.</p> <p>(G) Representative EM section of cyst from <i>dFadd ^f02804</i>/<i>dFadd ^f02804</i> testis. Essentially all spermatids have failed to individualize.</p> <p>(H) EM section of cyst from <i>Dredd ^B118</i>/<i>Dredd ^B118</i> testis in which individualization has failed to occur. In some other cysts from this same male, individualization proceeded apparently normally (data not shown).</p></div

The <i>bln¹</i> P-Element Insertion, Which Inhibits Cyt-c-d Expression, Results in Pleiotropic Defects in Spermatogenesis

<div><p>(A) Genomic organization of the cyt-c-d region. Upper half of the panel illustrates the structure of the region, as described by <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020015#pbio-0020015-Arama1" target="_blank">Arama et al. (2003</a>). The lower half of the panel indicates the relative locations of several other genes in the region, as annotated by the Berkeley Drosophila Genome Project (<a href="http://flybase.bio.indiana.edu/search/" target="_blank">http://flybase.bio.indiana.edu/search/</a>) as of August 2002. The <i>bln¹</i> P element is inserted within the cyt-c-d transcription unit. This P element is also inserted within the transcription unit of a second gene, <i>CR31808-RA</i> (<i>RE70695</i>). Both of these genes and the <i>bln¹</i> P element reside within the intron of a third gene, <i>CG31782</i>.</p> <p>(B and D) Wild-type and <i>bln¹</i> testis, respectively, stained with anti-active DRICE antibodies. Active DRICE immunoreactivity is eliminated in <i>bln¹</i> testis, as described in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020015#pbio-0020015-Arama1" target="_blank">Arama et al. (2003</a>).</p> <p>(C and E) Wild-type and <i>bln¹</i> testis, respectively, stained with AXO49 antibodies (blue), which recognize polyglycylated β2tub present in axonemal microtubules, and phalloidin (red). Polyglycylation occurs prior to individualization (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020015#pbio-0020015-Bressac1" target="_blank">Bressac et al. 1995</a>). Axonemes of elongated cysts from wild-type flies stain with AXO49 (C), while those from <i>bln¹</i> males do not (E).</p> <p>(F–I) EMs of cysts of different developmental stages from wild-type (F and G) and <i>bln¹</i> (H) testis. (F) Wild-type cyst prior to individualization. Note the structures of the major and minor mitochondrial derivatives, in particular the fact that the major mitochondrial derivative is increased in size and is electron dense. (G) Wild-type cyst following individualization. (H) Representative example of the most mature cysts found in <i>bln¹</i> testis. Note the dramatically increased cell size and the lack of differentiation of the major and mitochondrial derivatives, as compared to wild-type.</p></div

Active DRICE Is Eliminated from the Cytoplasm of Wild-Type Spermatids Following Passage of the Individualization Complex, but Not from Spermatids in Which Caspase Activity Has Been Inhibited

<div><p>(A) Cystic bulge from a wild-type cyst stained with active DRICE (red). The cystic bulge (arrowhead) is moving to the left. Active DRICE staining is absent in areas of the spermatid bundle that the individualization complex has passed through and in which excess cytoplasm has been eliminated (arrow).</p> <p>(B) Cystic bulge from a β2tub-p35 cyst. The cystic bulge (arrowhead) is decreased in size, and active DRICE is present in areas of the spermatid bundle through which the individualization complex has moved (arrows). These observations suggest caspase inhibition results in at least a partial failure to eliminate excess cytoplasm, but that this is not necessarily associated with lack of movement of the individualization complex.</p></div

<i>driceless</i> Males Lack Active Drice Staining and Show Defects in Individualization

<div><p>(A) Testis from <i>driceless</i> male stained with active DRICE. Active DRICE staining is eliminated.</p> <p>(B) Elongated cysts from <i>driceless</i> male. AXO49 staining (blue) outlines the location of three cystic bulges. Individualization complexes (arrows) are marked with phalloidin (red).</p> <p>(C) Example of a cyst from a <i>driceless</i> male in which individualization has proceeded normally.</p> <p>(D) Example of a cyst from a <i>driceless</i> male in which individualization has failed to occur.</p> <p>(E) Boxed area in (D) shown at higher magnification. A region in which individualization has failed is outlined with a dashed line.</p></div