scholarly journals A Protamine Knockdown Mimics the Function of Sd in Drosophila melanogaster

2020 ◽  
Vol 10 (6) ◽  
pp. 2111-2115 ◽  
Author(s):  
Luke F. Gingell ◽  
Janna R. McLean
Keyword(s):  
Drosophila Melanogaster ◽  
Nuclear Import ◽  
Nuclear Transport ◽  
Protein A ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Gene Complex ◽  
Unique Role ◽  
Spermatid Nucleus ◽  
Import And Export

Segregation Distorter (SD) is an autosomal meiotic drive system found worldwide in natural populations of Drosophila melanogaster. This gene complex induces the preferential and nearly exclusive transmission of the SD chromosome in SD/SD+ males. This selfish propagation occurs through the interplay of the Sd locus, its enhancers and the Rsps locus during spermatid development. The key distorter locus, Sd, encodes a truncated but enzymatically active RanGAP (RanGTPase-activating protein), a key nuclear transport factor in the Ran signaling pathway. When encoded by Sd, RanGAP is mislocalized to the nucleus interior, which then traps Ran inside the nucleus and disrupts nuclear import. As a result of this aberrant nuclear transport, a process known as the histone-to-protamine transition that is required for proper spermatid condensation fails to occur in SD/SD+ males. In this process, sperm-specific protamine proteins enter the spermatid nucleus and replace the formerly chromatin-complexed histones. Previously, we have shown that mutations affecting nuclear import and export can enhance distortion in an SD background, thus verifying that a defect in nuclear transport is responsible for the unequal transmission of chromosomes. Herein, we show that specifically reducing protamines induces distortion in an SD background, verifying that protamines are transported via the RanGAP/GEF pathway and indicating that E(SD) plays a significant and unique role in the process of distortion.

scholarly journals Rapid Evolution of a Coadapted Gene Complex: Evidence From the Segregation Distorter (SD) System of Meiotic Drive in Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 143 (4) ◽  
pp. 1675-1688 ◽  
Author(s):  
Michael F Palopoli ◽  
Chung-I Wu
Keyword(s):  
Drosophila Melanogaster ◽  
Rapid Evolution ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Pericentromeric Region ◽  
Genomic Region ◽  
Gene Complex ◽  
Segregation Distorter ◽  
Normal Homologue ◽  
Coadapted Gene Complex

Abstract Segregation Distorter (SD) is a system of meiotic drive found in natural populations of Drosophila melanogaster. Males heterozygous for an SD second chromosome and a normal homologue (SD  +) produce predominantly SD-bearing sperm. The coadapted gene complex responsible for this transmission advantage spans the second chromosome centromere, consisting of three major and several minor interacting loci. To investigate the evolutionary history of this system, we surveyed levels of polymorphism and divergence at six genes that together encompass this pericentromeric region and span seven map units. Interestingly, there was no discernible divergence between SD and SD  + chromosomes for any of these molecular markers. Furthermore, SD chromosomes harbored much less polymorphism than did SD  + chromosomes. The results suggest that the SD system evolved recently, swept to appreciable frequencies worldwide, and carried with it the entire second chromosome centromeric region (roughly 10% of the genome). Despite its well-documented genetic complexity, this coadapted system appears to have evolved on a time scale that is much shorter than can be gauged using nucleotide substitution data. Finally, the large genomic region hitchhiking with SD indicates that a multilocus, epistatically selected system could affect the levels of DNA polymorphism observed in regions of reduced recombination.

scholarly journals Armadillo nuclear import is regulated by cytoplasmic anchor Axin and nuclear anchor dTCF/Pan

Development ◽  
2001 ◽  
Vol 128 (11) ◽  
pp. 2107-2117 ◽  
Author(s):  
Nicholas S. Tolwinski ◽  
Eric Wieschaus
Keyword(s):  
Drosophila Melanogaster ◽  
Plasma Membrane ◽  
Nuclear Import ◽  
Current Model ◽  
Cellular Distribution ◽  
Nuclear Retention ◽  
Binding Partners ◽  
Wingless Signaling ◽  
Anchoring System ◽  
Import And Export

Drosophila melanogaster Armadillo plays two distinct roles during development. It is a component of adherens junctions, and functions as a transcriptional activator in response to Wingless signaling. In the current model, Wingless signal causes stabilization of cytoplasmic Armadillo allowing it to enter the nucleus where it can activate transcription. However, the mechanism of nuclear import and export remains to be elucidated. In this study, we show that two gain-of-function alleles of Armadillo activate Wingless signaling by different mechanisms. The S10 allele was previously found to localize to the nucleus, where it activates transcription. In contrast, the ΔArm allele localizes to the plasma membrane, and forces endogenous Arm into the nucleus. Therefore, ΔArm is dependent on the presence of a functional endogenous allele of arm to activate transcription. We show that ΔArm may function by titrating Axin protein to the membrane, suggesting that it acts as a cytoplasmic anchor keeping Arm out of the nucleus. In axin mutants, Arm is localized to the nuclei. We find that nuclear retention is dependent on dTCF/Pangolin. This suggests that cellular distribution of Arm is controlled by an anchoring system, where various nuclear and cytoplasmic binding partners determine its localization.

scholarly journals O-GlcNAc modification of nuclear pore complexes accelerates bi-directional transport

2020 ◽  
Author(s):  
Tae Yeon Yoo ◽  
Timothy J Mitchison
Keyword(s):  
Nuclear Import ◽  
Nuclear Transport ◽  
Super Resolution ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Permeability Barrier ◽  
Nuclear Pore Complexes ◽  
Facilitated Diffusion ◽  
Import And Export ◽  
Pore Complexes

AbstractMacromolecular transport across the nuclear envelope depends on facilitated diffusion through nuclear pore complexes (NPCs). The interior of NPCs contains a permeability barrier made of phenylalanine-glycine (FG) repeat domains that selectively facilitates the permeation of cargoes bound to nuclear transport receptors (NTRs). FG repeats in NPC are a major site of O-linked N-acetylglucosamine (O-GlcNAc) modification, but the functional role of this modification in nucleocytoplasmic transport is unclear. We developed high-throughput assays based on optogenetic probes to quantify the kinetics of nuclear import and export in living human cells. We found that increasing O-GlcNAc modification of the NPC accelerated NTR-facilitated nucleocytoplasmic transport of proteins in both directions, and decreasing modification slowed transport. Super-resolution imaging revealed strong enrichment of O-GlcNAc at the FG-repeat barrier. O-GlcNAc modification also accelerated passive permeation of a small, inert protein through NPCs. We conclude that O-GlcNAc modification accelerates nucleocytoplasmic transport by enhancing the non-specific permeability the FG-repeat barrier, perhaps by steric inhibition of interactions between FG repeats.SummaryNuclear pore complexes mediate nuclear transport and are highly modified with O-linked N-acetylglucosamine (O-GlcNAc) on FG repeat domains. Using a new quantitative live-cell imaging assay, Yoo and Mitchison demonstrate acceleration of nuclear import and export by O-GlcNAc modification.

scholarly journals Variation in Y Chromosome Segregation in Natural Populations of Drosophila melanogaster

Genetics ◽  
1987 ◽  
Vol 115 (1) ◽  
pp. 143-151
Author(s):  
Andrew G Clark
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Chromosome Segregation ◽  
Significant Variation ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Adult Offspring ◽  
Functional Variation ◽  
Y Chromosomes ◽  
Geographic Origins

ABSTRACT Functional variation among Y chromosomes in natural populations of Drosophila melanogaster was assayed by a segregation study. A total of 36 Y chromosomes was extracted and ten generations of replacement backcrossing yielded stocks with Y chromosomes in two different genetic backgrounds. Eleven of the Y chromosomes were from diverse geographic origins, and the remaining 25 were from locally captured flies. Segregation of sexes in adult offspring was scored for the four possible crosses among the two backgrounds with each Y chromosome. Although the design confounds meiotic drive and effects on viability, statistical partitioning of these effects reveals significant variation among lines in Y chromosome segregation. Results are discussed in regards to models of Y-linked segregation and viability effects, which suggest that Y-linked adaptive polymorphism is unlikely.

scholarly journals The mechanism of inhibition of Ran-dependent nuclear transport by cellular ATP depletion

2002 ◽  
Vol 157 (6) ◽  
pp. 963-974 ◽  
Author(s):  
Eric D. Schwoebel ◽  
Thai H. Ho ◽  
Mary Shannon Moore
Keyword(s):  
Nuclear Import ◽  
Nuclear Transport ◽  
Intact Cell ◽  
Transport Processes ◽  
Atp Depletion ◽  
Transport Pathways ◽  
Atp Production ◽  
Import And Export

Rran-dependent nuclear transport requires a nuclear pool of RanGTP both for the assembly of export complexes and the disassembly of import complexes. Accordingly, in order for these processes to proceed, Ran-dependent nuclear import and export assays in vitro require the addition of GTP to produce RanGTP. Notably, no ATP requirement can be detected for these transport processes in vitro. But in vivo, when cells are depleted of ATP by the addition of sodium azide and 2-deoxyglucose to block ATP production by oxidative phosphorylation and glycolysis, respectively, Ran-dependent nuclear import and export are rapidly inhibited. This raised the question of whether there is an ATP requirement for these nuclear transport pathways in an intact cell that has remained undetected in vitro. Here we report that the free (but not total) GTP concentration rapidly drops to an undetectable level upon ATP depletion as does the availability of RanGTP. Our conclusion is that the inhibition of Ran-dependent nuclear transport observed upon ATP depletion in vivo results from a shortage of RanGTP rather than the inhibition of some ATP-dependent process.

scholarly journals How SARS-CoV-2 and Other Viruses Build an Invasion Route to Hijack the Host Nucleocytoplasmic Trafficking System

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1424
Author(s):  
Elma Sakinatus Sajidah ◽  
Keesiang Lim ◽  
Richard W. Wong
Keyword(s):  
Nuclear Import ◽  
Nuclear Transport ◽  
Antiviral Treatment ◽  
Nuclear Pore ◽  
Nucleocytoplasmic Trafficking ◽  
Nucleocytoplasmic Shuttling ◽  
Transport Receptors ◽  
Import And Export ◽  
Viral Components ◽  
Host Nucleus

The host nucleocytoplasmic trafficking system is often hijacked by viruses to accomplish their replication and to suppress the host immune response. Viruses encode many factors that interact with the host nuclear transport receptors (NTRs) and the nucleoporins of the nuclear pore complex (NPC) to access the host nucleus. In this review, we discuss the viral factors and the host factors involved in the nuclear import and export of viral components. As nucleocytoplasmic shuttling is vital for the replication of many viruses, we also review several drugs that target the host nuclear transport machinery and discuss their feasibility for use in antiviral treatment.

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