scholarly journals Autophagic degradation of dBruce controls DNA fragmentation in nurse cells during late Drosophila melanogaster oogenesis

2010 ◽  
Vol 190 (4) ◽  
pp. 523-531 ◽  
Author(s):  
Ioannis P. Nezis ◽  
Bhupendra V. Shravage ◽  
Antonia P. Sagona ◽  
Trond Lamark ◽  
Geir Bjørkøy ◽  
...  
Keyword(s):  
Cell Death ◽  
Drosophila Melanogaster ◽  
Dna Fragmentation ◽  
Nurse Cell ◽  
Nurse Cells ◽  
Cell Nuclei ◽  
Cytoplasmic Material ◽  
Fragmented Dna ◽  
Egg Chambers ◽  
Autophagic Degradation

Autophagy is an evolutionarily conserved pathway responsible for degradation of cytoplasmic material via the lysosome. Although autophagy has been reported to contribute to cell death, the underlying mechanisms remain largely unknown. In this study, we show that autophagy controls DNA fragmentation during late oogenesis in Drosophila melanogaster. Inhibition of autophagy by genetically removing the function of the autophagy genes atg1, atg13, and vps34 resulted in late stage egg chambers that contained persisting nurse cell nuclei without fragmented DNA and attenuation of caspase-3 cleavage. The Drosophila inhibitor of apoptosis (IAP) dBruce was found to colocalize with the autophagic marker GFP-Atg8a and accumulated in autophagy mutants. Nurse cells lacking Atg1 or Vps34 in addition to dBruce contained persisting nurse cell nuclei with fragmented DNA. This indicates that autophagic degradation of dBruce controls DNA fragmentation in nurse cells. Our results reveal autophagic degradation of an IAP as a novel mechanism of triggering cell death and thereby provide a mechanistic link between autophagy and cell death.

Drosophila rhino Encodes a Female-Specific Chromo-domain Protein That Affects Chromosome Structure and Egg Polarity

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1117-1134 ◽  
Author(s):  
Alison M Volpe ◽  
Heidi Horowitz ◽  
Constance M Grafer ◽  
Stephen M Jackson ◽  
Celeste A Berg
Keyword(s):  
Nurse Cell ◽  
Chromosome Structure ◽  
Nurse Cells ◽  
Embryonic Patterning ◽  
Loss Of Function ◽  
Cell Nuclei ◽  
Heterochromatin Protein 1 ◽  
Chromo Domain ◽  
Egg Chambers ◽  
Female Specific

Abstract Here we describe our analyses of Rhino, a novel member of the Heterochromatin Protein 1(HP1) subfamily of chromo box proteins. rhino (rhi) is expressed only in females and chiefly in the germline, thus providing a new tool to dissect the role of chromo-domain proteins in development. Mutations in rhi disrupt eggshell and embryonic patterning and arrest nurse cell nuclei during a stage-specific reorganization of their polyploid chromosomes, a mitotic-like state called the “five-blob” stage. These visible alterations in chromosome structure do not affect polarity by altering transcription of key patterning genes. Expression levels of gurken (grk), oskar (osk), bicoid (bcd), and decapentaplegic (dpp) transcripts are normal, with a slight delay in the appearance of bcd and dpp mRNAs. Mislocalization of grk and osk transcripts, however, suggests a defect in the microtubule reorganization that occurs during the middle stages of oogenesis and determines axial polarity. This defect likely results from aberrant Grk/Egfr signaling at earlier stages, since rhi mutations delay synthesis of Grk protein in germaria and early egg chambers. In addition, Grk protein accumulates in large, actin-caged vesicles near the endoplasmic reticulum of stages 6–10 egg chambers. We propose two hypotheses to explain these results. First, Rhi may play dual roles in oogenesis, independently regulating chromosome compaction in nurse cells at the end of the unique endoreplication cycle 5 and repressing transcription of genes that inhibit Grk synthesis. Thus, loss-of-function mutations arrest nurse cell chromosome reorganization at the five-blob stage and delay production or processing of Grk protein, leading to axial patterning defects. Second, Rhi may regulate chromosome compaction in both nurse cells and oocyte. Loss-of-function mutations block nurse cell nuclear transitions at the five-blob stage and activate checkpoint controls in the oocyte that arrest Grk synthesis and/or inhibit cytoskeletal functions. These functions may involve direct binding of Rhi to chromosomes or may involve indirect effects on pathways controlling these processes.

scholarly journals Mouse oocytes develop in cysts with the help of nurse cells

2021 ◽  
Author(s):  
Wanbao Niu ◽  
Allan C Spradling
Keyword(s):  
Cell Death ◽  
Germ Cells ◽  
Nurse Cell ◽  
Cell Selection ◽  
Nurse Cells ◽  
Cell Turnover ◽  
Cell Nuclei ◽  
Body Formation ◽  
Mouse Oocytes ◽  
Cytoplasmic Transfer

Mammalian oocytes develop initially in cysts containing many more germ cells than the primordial oocytes they generate. We identified abundant nurse cells with reduced unique molecular identifiers (UMI)/cell from ovaries aged E14.5 to P1. Low UMI nurse cells are found in cysts and express the same major meiotic genes as pro-oocytes of the same stage, suggesting they are oocyte sisters that are signaled to transfer cytoplasm at different times and only subsequently diverge. Oocyte vs nurse cell selection occurs in cysts with a robust microtubule cytoskeleton, that closely interact with somatic cells and that develop a dense actin cytoskeleton around nurse cell nuclei that are held back from cytoplasmic transfer. Mouse and Drosophila nurse cells undergo programmed cell death by acidification from adjacent somatic pre-granulosa cells that express V-ATPases and cathepsin proteins. Disrupting acidification in cultured mouse ovaries blocked nurse cell turnover. About 200 genes are induced in mouse dictyate oocytes as previously reported, including Tuba1c and Tubb2b, genes that we find contribute to Balbiani body formation. Thus, mouse oocytes are specified within germline cysts and develop with the assistance of nurse cells using highly conserved mechanisms.

scholarly journals Germline Cell Death Is Inhibited byP-Element Insertions Disrupting thedcp-1/pitaNested Gene Pair in Drosophila

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 1881-1888 ◽  
Author(s):  
Bonni Laundrie ◽  
Jeanne S Peterson ◽  
Jason S Baum ◽  
Jeffrey C Chang ◽  
Dana Fileppo ◽  
...  
Keyword(s):  
Cell Death ◽  
Nurse Cell ◽  
Zinc Finger Protein ◽  
P Element ◽  
Germline Cell ◽  
Developmentally Regulated ◽  
Developmental Abnormalities ◽  
Egg Chambers ◽  
Caspase Gene ◽  
Active Caspase

AbstractGermline cell death in Drosophila oogenesis is controlled by distinct signals. The death of nurse cells in late oogenesis is developmentally regulated, whereas the death of egg chambers during mid-oogenesis is induced by environmental stress or developmental abnormalities. P-element insertions in the caspase gene dcp-1 disrupt both dcp-1 and the outlying gene, pita, leading to lethality and defective nurse cell death in late oogenesis. By isolating single mutations in the two genes, we have found that the loss of both genes contributes to this ovary phenotype. Mutants of pita, which encodes a C2H2 zinc-finger protein, are homozygous lethal and show dumpless egg chambers and premature nurse cell death in germline clones. Early nurse cell death is not observed in the dcp-1/pita double mutants, suggesting that dcp-1+ activity is required for the mid-oogenesis cell death seen in pita mutants. dcp-1 mutants are viable and nurse cell death in late oogenesis occurs normally. However, starvation-induced germline cell death during mid-oogenesis is blocked, leading to a reduction and inappropriate nuclear localization of the active caspase Drice. These findings suggest that the combinatorial loss of pita and dcp-1 leads to the increased survival of abnormal egg chambers in mutants bearing the P-element alleles and that dcp-1 is essential for cell death during mid-oogenesis.

Apoptosis in late stage Drosophila nurse cells does not require genes within the H99 deficiency

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1075-1082 ◽  
Author(s):  
K. Foley ◽  
L. Cooley
Keyword(s):  
Dna Fragmentation ◽  
Late Stage ◽  
Expression Patterns ◽  
Nuclear Material ◽  
Nurse Cells ◽  
Wild Type ◽  
Negative Regulators ◽  
Egg Chambers ◽  
Positive Regulators ◽  
Egg Chamber

We have determined that nurse cells are cleared from the Drosophila egg chamber by apoptosis. DNA fragmentation begins in nurse cells at stage 12, following the completion of cytoplasm transfer from the nurse cells to the oocyte. During stage 13, nurse cells increasingly contain highly fragmented DNA and disappear from the egg chamber concomitantly with the formation of apoptotic vesicles containing highly fragmented nuclear material. In dumpless mutant egg chambers that fail to complete cytoplasm transport from the nurse cells, DNA fragmentation is markedly delayed and begins during stage 13, when the majority of cytoplasm is lost from the nurse cells. These data suggest the presence of cytoplasmic factors in nurse cells that inhibit the initiation of DNA fragmentation. In addition, we have examined the ovarian expression patterns of regulatory genes implicated in Drosophila apoptosis. The positive regulators, reaper (rpr), head involution defective (hid) and grim, as well as the negative regulators, DIAP1 and DIAP2, are transcribed during oogenesis. However, germline clones homozygous for the deficiency Df(3)H99, which deletes rpr, hid and grim, undergo oogenesis in a manner morphologically indistinguishable from wild type, indicating that genes within this region are not necessary for apoptosis in nurse cells.

Studies on the female-sterile phenotype of 1(1)su(f) ts76a, a temperature-sensitive allele of the suppressor of forked mutation in Drosophila melanogaster

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 247-256
Author(s):  
Thomas G. Wilson
Keyword(s):  
Cell Death ◽  
Drosophila Melanogaster ◽  
Follicle Cell ◽  
Lethal Mutation ◽  
Female Sterility ◽  
Temperature Sensitive ◽  
Egg Chambers ◽  
A Cell ◽  
Sensitive Allele

A new allele of the suppressor of forked [su(f)] mutation in Drosophila melanogaster has been found and designated 1(1)su(f)ts76a. It is temperature-sensitive for suppression of forked (f) and has additional temperature-sensitive phenotypes of lethality, female sterility, and abnormal bristle formation at 29 °C. It closely resembles two other conditional alleles of su(f), 1(1)su(f)ts67g and 1(1)ts726. Female sterility at 29 °C is characterized by both disorganized egg chambers in the ovarioles and also chorion-deficient oocytes. Both of these abnormalities may be the result of premature follicle cell death. The observations on 1(1)su(f)ts76a are consistent with the proposal that the similar allele, 1(1)ts726, is a cell-lethal mutation specifically affecting mitotically active cells.

scholarly journals Autophagy as a trigger for cell death: Autophagic degradation of inhibitor of apoptosis dBruce controls DNA fragmentation during late oogenesis in Drosophila

Autophagy ◽  
2010 ◽  
Vol 6 (8) ◽  
pp. 1214-1215 ◽  
Author(s):  
Ioannis P. Nezis ◽  
Bhupendra V. Shravage ◽  
Antonia P. Sagona ◽  
Terje Johansen ◽  
Eric H. Baehrecke ◽  
...  
Keyword(s):  
Cell Death ◽  
Dna Fragmentation ◽  
Inhibitor Of Apoptosis ◽  
Autophagic Degradation

Drosophila quail, a villin-related protein, bundles actin filaments in apoptotic nurse cells

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5645-5657 ◽  
Author(s):  
N. Matova ◽  
S. Mahajan-Miklos ◽  
M.S. Mooseker ◽  
L. Cooley
Keyword(s):  
Actin Filaments ◽  
Nurse Cell ◽  
Calcium Concentration ◽  
Developmental Model ◽  
Free Calcium ◽  
Nurse Cells ◽  
Filamentous Actin ◽  
Actin Bundle ◽  
High Calcium ◽  
Egg Chambers

Drosophila Quail protein is required for the completion of fast cytoplasm transport from nurse cells to the oocyte, an event critical for the production of viable oocytes. The abundant network of cytoplasmic filamentous actin, established at the onset of fast transport, is absent in quail mutant egg chambers. Previously, we showed that Quail is a germline-specific protein with sequence homology to villin, a vertebrate actin-regulating protein. In this study, we combined biochemical experiments with observations in egg chambers to define more precisely the function of this protein in the regulation of actin-bundle assembly in nurse cells. We report that recombinant Quail can bind and bundle filamentous actin in vitro in a manner similar to villin at a physiological calcium concentration. In contrast to villin, Quail is unable to sever or cap filamentous actin, or to promote nucleation of new actin filaments at a high calcium concentration. Instead, Quail bundles the filaments regardless of the calcium concentration. In vivo, the assembly of nurse-cell actin bundles is accompanied by extensive perforation of the nurse-cell nuclear envelopes, and both of these phenomena are manifestations of nurse-cell apoptosis. To investigate whether free calcium levels are affected during apoptosis, we loaded egg chambers with the calcium indicator Indo-1. Our observations indicate a rise in free calcium in the nurse-cell cytoplasm coincident with the permeabilization of the nuclear envelopes. We also show that human villin expressed in the Drosophila germline could sense elevated cytoplasmic calcium; in nurse cells with reduced levels of Quail protein, villin interfered with actin-bundle stability. We conclude that Quail efficiently assembles actin filaments into bundles in nurse cells and maintains their stability under fluctuating free calcium levels. We also propose a developmental model for the fast phase of cytoplasm transport incorporating findings presented in this study.

scholarly journals DNA SYNTHESIS IN THE OOPLASM OF DROSOPHILA MELANOGASTER

1966 ◽  
Vol 28 (2) ◽  
pp. 199-208 ◽  
Author(s):  
F. A. Muckenthaler ◽  
A. P. Mahowald
Keyword(s):  
Drosophila Melanogaster ◽  
Tritiated Thymidine ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Cell Nuclei ◽  
Electron Microscopic ◽  
Tissue Sections ◽  
Electron Microscopes ◽  
High Level ◽  
Silver Grains

Tritiated thymidine was injected into 2-day-old Drosophila melanogaster females, and tissue sections were prepared from the ovary for radioautography with both the light and electron microscopes. Besides the expected incorporation of H3-thymidine into nuclei of nurse cells and follicle cells, there was a relatively high level of incorporation of label into ooplasmic DNA. The highest level of incorporation occurred at stage 12. At the same time, the 15 nurse cell nuclei also incorporate thymidine in spite of the fact that they are breaking down and degenerating. The label in the ooplasm is not removed by extraction with DNase (although this removes nuclear label) unless extraction is preceded by a treatment with protease. Electron microscopic radioautography revealed that 36% of the silver grains resulting from decay of H3-thymidine are found over mitochondria, with a further 28% being located within 0.25 µ of these organelles. The remaining 36% of the silver grains was not found to be associated with any organelles, and it probably represents synthesis in the cytoplasm by the "storage DNA" characteristic of many eggs. It is suggested that one mechanism acting throughout the egg chamber is responsible for the synchronous synthesis of DNA in the degenerating nurse cells, in the mitochondria of the egg, and in the "storage DNA" of the ooplasm.

scholarly journals Effector caspase Dcp-1 and IAP protein Bruce regulate starvation-induced autophagy during Drosophila melanogaster oogenesis

2008 ◽  
Vol 182 (6) ◽  
pp. 1127-1139 ◽  
Author(s):  
Ying-Chen Claire Hou ◽  
Suganthi Chittaranjan ◽  
Sharon González Barbosa ◽  
Kimberly McCall ◽  
Sharon M. Gorski
Keyword(s):  
Cell Death ◽  
Drosophila Melanogaster ◽  
Molecular Mechanisms ◽  
Cultured Cells ◽  
Mitogen Activated Protein Kinase ◽  
Nuclear Condensation ◽  
Effector Caspase ◽  
Apoptosis Protein ◽  
Egg Chambers

A complex relationship exists between autophagy and apoptosis, but the regulatory mechanisms underlying their interactions are largely unknown. We conducted a systematic study of Drosophila melanogaster cell death–related genes to determine their requirement in the regulation of starvation-induced autophagy. We discovered that six cell death genes—death caspase-1 (Dcp-1), hid, Bruce, Buffy, debcl, and p53—as well as Ras–Raf–mitogen activated protein kinase signaling pathway components had a role in autophagy regulation in D. melanogaster cultured cells. During D. melanogaster oogenesis, we found that autophagy is induced at two nutrient status checkpoints: germarium and mid-oogenesis. At these two stages, the effector caspase Dcp-1 and the inhibitor of apoptosis protein Bruce function to regulate both autophagy and starvation-induced cell death. Mutations in Atg1 and Atg7 resulted in reduced DNA fragmentation in degenerating midstage egg chambers but did not appear to affect nuclear condensation, which indicates that autophagy contributes in part to cell death in the ovary. Our study provides new insights into the molecular mechanisms that coordinately regulate autophagic and apoptotic events in vivo.

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