The ER morphology-regulating lunapark protein induces the formation of stacked bilayer discs

Lunapark (Lnp) is a conserved membrane protein that localizes to and stabilizes three-way junctions of the tubular ER network. In higher eukaryotes, phosphorylation of Lnp may contribute to the conversion of the ER from tubules to sheets during mitosis. Here, we report on the reconstitution of purified Lnp with phospholipids. Surprisingly, Lnp induces the formation of stacked membrane discs. Each disc is a bicelle, with Lnp sitting in the bilayer facing both directions. The interaction between bicelles is mediated by the cytosolic domains of Lnp, resulting in a constant distance between the discs. A phosphomimetic Lnp mutant shows reduced bicelle stacking. Based on these results, we propose that Lnp tethers ER membranes in vivo in a cell cycle–dependent manner. Lnp appears to be the first membrane protein that induces the formation of stacked bicelles.

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The ubiquitin-proteasome pathway regulates survivin degradation in a cell cycle-dependent manner

Journal of Cell Science ◽

10.1242/jcs.113.23.4363 ◽

2000 ◽

Vol 113 (23) ◽

pp. 4363-4371 ◽

Cited By ~ 3

Author(s):

J. Zhao ◽

T. Tenev ◽

L.M. Martins ◽

J. Downward ◽

N.R. Lemoine

Keyword(s):

Cell Cycle ◽

Proteasome Inhibitors ◽

Dependent Manner ◽

Ubiquitin Proteasome Pathway ◽

Apoptosis Protein ◽

Ubiquitin Proteasome ◽

A Cell ◽

Proteasome Pathway ◽

Cycle Dependent

Survivin, a human inhibitor of apoptosis protein (IAP), plays an important role in both cell cycle regulation and inhibition of apoptosis. Survivin is expressed in cells during the G(2)/M phase of the cell cycle, followed by rapid decline of both mRNA and protein levels at the G(1) phase. It has been suggested that cell cycle-dependent expression of survivin is regulated at the transcriptional level. In this study we demonstrate involvement of the ubiquitin-proteasome pathway in post-translational regulation of survivin. Survivin is a short-lived protein with a half-life of about 30 minutes and proteasome inhibitors greatly stabilise survivin in vivo. Expression of the survivin gene under the control of the CMV promoter cannot block cell cycle-dependent degradation of the protein. Proteasome inhibitors can block survivin degradation during the G(1) phase and polyubiquitinated derivatives can be detected in vivo. Mutation of critical amino acid residues within the baculovirus IAP repeat (BIR) domain or truncation of the N terminus or the C terminus sensitises survivin to proteasome degradation. Together, these results indicate that the ubiquitin-proteasome pathway regulates survivin degradation in a cell cycle-dependent manner and structural changes greatly destabilise the survivin protein.

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Truncated APC regulates the transcriptional activity of β-catenin in a cell cycle dependent manner

Human Molecular Genetics ◽

10.1093/hmg/ddl464 ◽

2006 ◽

Vol 16 (2) ◽

pp. 199-209 ◽

Cited By ~ 38

Author(s):

Jean Schneikert ◽

Annette Grohmann ◽

Jürgen Behrens

Keyword(s):

Cell Cycle ◽

Transcriptional Activity ◽

Dependent Manner ◽

A Cell ◽

Cycle Dependent

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A Novel Transcriptional Repression Domain Mediates p21WAF1/CIP1 Induction of p300 Transactivation

Molecular and Cellular Biology ◽

10.1128/mcb.20.8.2676-2686.2000 ◽

2000 ◽

Vol 20 (8) ◽

pp. 2676-2686 ◽

Cited By ~ 88

Author(s):

Andrew W. Snowden ◽

Lisa A. Anderson ◽

Gill A. Webster ◽

Neil D. Perkins

Keyword(s):

Cell Cycle ◽

Transcriptional Activation ◽

Transcriptional Repression ◽

Kinase Inhibitor ◽

Core Promoter ◽

Dependent Manner ◽

Creb Binding Protein ◽

Cycle Dependent ◽

Repression Domain

ABSTRACT The transcriptional coactivators p300 and CREB binding protein (CBP) are important regulators of the cell cycle, differentiation, and tumorigenesis. Both p300 and CBP are targeted by viral oncoproteins, are mutated in certain forms of cancer, are phosphorylated in a cell cycle-dependent manner, interact with transcription factors such as p53 and E2F, and can be found complexed with cyclinE-Cdk2 in vivo. Moreover, p300-deficient cells show defects in proliferation. Here we demonstrate that transcriptional activation by both p300 and CBP is stimulated by coexpression of the cyclin-dependent kinase inhibitor p21WAF/CIP1. Significantly this stimulation is independent of both the inherent histone acetyltransferase (HAT) activity of p300 and CBP and of the previously reported carboxyl-terminal binding site for cyclinE-Cdk2. Rather, we describe a previously uncharacterized transcriptional repression domain (CRD1) within p300. p300 transactivation is stimulated through derepression of CRD1 by p21. Significantly p21 regulation of CRD1 is dependent on the nature of the core promoter. We suggest that CRD1 provides a novel mechanism through which p300 and CBP can switch activities between the promoters of genes that stimulate growth and those that enhance cell cycle arrest.

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Ser68 phosphoregulation is essential for CENP-A deposition, centromere function and viability in mice

10.1101/2021.11.23.469796 ◽

2021 ◽

Author(s):

Yuting Liu ◽

Kehui Wang ◽

Li Huang ◽

Jicheng Zhao ◽

Xinpeng Chen ◽

...

Keyword(s):

Cell Cycle ◽

Cell Viability ◽

Histone H3 ◽

Dependent Manner ◽

Centromere Function ◽

Histone H3 Variant ◽

A Cell ◽

Cycle Dependent ◽

Spatiotemporal Control

Centromere identity is defined by nucleosomes containing CENP-A, a histone H3 variant. The deposition of CENP-A at centromeres is tightly regulated in a cell-cycle-dependent manner. We previously reported that the spatiotemporal control of centromeric CENP-A incorporation is mediated by the phosphorylation of CENP-A Ser68. However, a recent report argued that Ser68 phosphoregulation is dispensable for accurate CENP-A loading. Here, we report that the substitution of Ser68 of endogenous CENP-A with either Gln68 or Glu68 severely impairs CENP-A deposition and cell viability. We also find that mice harboring the corresponding mutations are lethal. Together, these results indicate that the dynamic phosphorylation of Ser68 ensures cell-cycle-dependent CENP-A deposition and cell viability.

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Gcn5-mediated acetylation at MBF-regulated promoters induces the G1/S transcriptional wave

Nucleic Acids Research ◽

10.1093/nar/gkz561 ◽

2019 ◽

Vol 47 (16) ◽

pp. 8439-8451 ◽

Cited By ~ 1

Author(s):

Alberto González-Medina ◽

Elena Hidalgo ◽

José Ayté

Keyword(s):

Cell Cycle ◽

Molecular Mechanisms ◽

Histone H3 ◽

Dependent Manner ◽

Saga Complex ◽

Lysine Residues ◽

Physical Barriers ◽

A Cell ◽

Cycle Dependent ◽

Regulated Promoters

Abstract In fission yeast, MBF-dependent transcription is inactivated at the end of S phase through a negative feedback loop that involves the co-repressors, Yox1 and Nrm1. Although this repression system is well known, the molecular mechanisms involved in MBF activation remain largely unknown. Compacted chromatin constitutes a barrier to activators accessing promoters. Here, we show that chromatin regulation plays a key role in activating MBF-dependent transcription. Gcn5, a part of the SAGA complex, binds to MBF-regulated promoters through the MBF co-activator Rep2 in a cell cycle-dependent manner and in a reverse correlation to the binding of the MBF co-repressors, Nrm1 or Yox1. We propose that the co-repressors function as physical barriers to SAGA recruitment onto MBF promoters. We also show that Gcn5 acetylates specific lysine residues on histone H3 in a cell cycle-regulated manner. Furthermore, either in a gcn5 mutant or in a strain in which histone H3 is kept in an unacetylated form, MBF-dependent transcription is downregulated. In summary, Gcn5 is required for the full activation and correct timing of MBF-regulated gene transcription.

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