Ipl1/Aurora-dependent phosphorylation of Sli15/INCENP regulates CPC–spindle interaction to ensure proper microtubule dynamics

Nakajima et al Abstract Dynamic microtubules facilitate chromosome arrangement before anaphase, whereas during anaphase microtubule stability assists chromosome separation. Changes in microtubule dynamics at the metaphase–anaphase transition are regulated by Cdk1. Cdk1-mediated phosphorylation of Sli15/INCENP promotes preanaphase microtubule dynamics by preventing chromosomal passenger complex (CPC; Sli15/INCENP, Bir1/Survivin, Nbl1/Borealin, Ipl1/Aurora) association with spindles. However, whether Cdk1 has sole control over microtubule … Continue reading

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Transient binding of an activator BH3 domain to the Bak BH3-binding groove initiates Bak oligomerization

Dai et al Abstract The mechanism by which the proapoptotic Bcl-2 family members Bax and Bak release cytochrome c from mitochondria is incompletely understood. In this paper, we show that activator BH3-only proteins bind tightly but transiently to the Bak hydrophobic BH3-binding groove to induce Bak oligomerization, liposome permeabilization, mitochondrial cytochrome c release, and cell death. Analysis by surface plasmon … Continue reading

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A PAR-1–dependent orientation gradient of dynamic microtubules directs posterior cargo transport in the Drosophila oocyte

Parton et al. Abstract Cytoskeletal organization is central to establishing cell polarity in various cellular contexts, including during messenger ribonucleic acid sorting in Drosophila melanogaster oocytes by microtubule (MT)-dependent molecular motors. However, MT organization and dynamics remain controversial in the oocyte. In this paper, we use rapid multichannel live-cell imaging with novel image analysis, tracking, and visualization tools to characterize … Continue reading

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The F-box protein Ppa is a common regulator of core EMT factors Twist, Snail, Slug, and Sip1

Lander et al Abstract A small group of core transcription factors, including Twist, Snail, Slug, and Sip1, control epithelial–mesenchymal transitions (EMTs) during both embryonic development and tumor metastasis. However, little is known about how these factors are coordinately regulated to mediate the requisite behavioral and fate changes. It was recently shown that a key mechanism for regulating Snail proteins is … Continue reading

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Signal transduction by reactive oxygen species

Finkel et al Abstract Although  historically viewed as purely harmful, recent evidence suggests that reactive oxygen species (ROS) function as important physiological regulators of intracellular signaling pathways. The specific effects of ROS are modulated in large part through the covalent modification of specific cysteine residues found within redox-sensitive target proteins. Oxidation of these specific and reactive cysteine residues in turn … Continue reading

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Sorting of GPI-anchored proteins into ER exit sites by p24 proteins is dependent on remodeled GPI

Fujita et al. Abstract Glycosylphosphatidylinositol (GPI) anchoring of proteins is a posttranslational modification occurring in the endoplasmic reticulum (ER). After GPI attachment, proteins are transported by coat protein complex II (COPII)-coated vesicles from the ER. Because GPI-anchored proteins (GPI-APs) are localized in the lumen, they cannot interact with cytosolic COPII components directly. Receptors that link GPI-APs to COPII are thought … Continue reading

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Cargo sorting to lysosome-related organelles regulates siRNA-mediated gene silencing

Abstract Mammals lacking BLOC-3 have impaired formation of melanosomes, a type of lysosome-related organelle (LRO), and, in earlier work, we found that a subunit of the BLOC-3 complex inhibits loading of Argonaute (Ago) proteins with small ribonucleic acids (RNAs) in Drosophila melanogaster cells. Small RNAs such as small interfering RNAs (siRNAs) direct Ago proteins to repress the stability of messenger … Continue reading

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