scholarly journals Physiological Importance and Identification of Novel Targets for the N-Terminal Acetyltransferase NatB

2006 ◽  
Vol 5 (2) ◽  
pp. 368-378 ◽  
Author(s):  
Robert Caesar ◽  
Jonas Warringer ◽  
Anders Blomberg
Keyword(s):  
Cell Cycle ◽  
Protein Function ◽  
Large Scale ◽  
Cell Cycle Progression ◽  
Physiological Role ◽  
Phenotypic Analysis ◽  
Physiological Importance ◽  
Actin Cable ◽  
Actin Cables ◽  
Dna Processing

ABSTRACT The N-terminal acetyltransferase NatB in Saccharomyces cerevisiae consists of the catalytic subunit Nat3p and the associated subunit Mdm20p. We here extend our present knowledge about the physiological role of NatB by a combined proteomics and phenomics approach. We found that strains deleted for either NAT3 or MDM20 displayed different growth rates and morphologies in specific stress conditions, demonstrating that the two NatB subunits have partly individual functions. Earlier reported phenotypes of the nat3Δ strain have been associated with altered functionality of actin cables. However, we found that point mutants of tropomyosin that suppress the actin cable defect observed in nat3Δ only partially restores wild-type growth and morphology, indicating the existence of functionally important acetylations unrelated to actin cable function. Predicted NatB substrates were dramatically overrepresented in a distinct set of biological processes, mainly related to DNA processing and cell cycle progression. Three of these proteins, Cac2p, Pac10p, and Swc7p, were identified as true NatB substrates. To identify N-terminal acetylations potentially important for protein function, we performed a large-scale comparative phenotypic analysis including nat3Δ and strains deleted for the putative NatB substrates involved in cell cycle regulation and DNA processing. By this procedure we predicted functional importance of the N-terminal acetylation for 31 proteins.

Mutations at sites involved in Suc1 binding inactivate Cdc2

1991 ◽  
Vol 11 (12) ◽  
pp. 6177-6184
Author(s):  
B Ducommun ◽  
P Brambilla ◽  
G Draetta
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Specific Interaction ◽  
Physiological Role ◽  
Negative Effects ◽  
Alanine Scanning Mutagenesis ◽  
Cycle Progression ◽  
Mutant Proteins ◽  
Additional Protein

suc1+ encodes an essential cell cycle regulator of the fission yeast Schizosaccharomyces pombe. Its product, a 13-kDa protein, interacts with the Cdc2 protein kinase. Both positive and negative effects on cell cycle progression have been attributed to Suc1. To date, the exact mechanisms and the physiological role of the interaction between Suc1 and Cdc2 remain unclear. Here we have studied the molecular basis of this association. We show that Cdc2 can bind Suc1 or its mammalian homolog directly in the absence of any additional protein component. Using an alanine scanning mutagenesis method, we analyzed the interaction between Cdc2 and Suc1. We show that the integrity of several domains on the Cdc2 protein, including sites directly involved in catalytic activity, is required for binding to Suc1. Furthermore, Cdc2 mutant proteins unable to bind Suc1 (but able to bind cyclins) are nonfunctional when overexpressed in S. pombe, indicating that a specific interaction with Suc1 is required for Cdc2 function.

Search, capture and signal: games microtubules and centrosomes play

2001 ◽  
Vol 114 (2) ◽  
pp. 247-255 ◽  
Author(s):  
S.C. Schuyler ◽  
D. Pellman
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cytoplasmic Dynein ◽  
Cell Cycle Checkpoint ◽  
Cellular Polarity ◽  
Cycle Progression ◽  
Cycle Checkpoint ◽  
Dividing Cells ◽  
Actin Cables ◽  
Type V

Accurate distribution of the chromosomes in dividing cells requires coupling of cellular polarity cues with both the orientation of the mitotic spindle and cell cycle progression. Work in budding yeast has demonstrated that cytoplasmic dynein and the kinesin Kip3p define redundant pathways that ensure proper spindle orientation. Furthermore, it has been shown that the Kip3p pathway components Kar9p and Bim1p (Yeb1p) form a complex that provides a molecular link between cortical polarity cues and spindle microtubules. Recently, other studies indicated that the cortical localization of Kar9p depends upon actin cables and Myo2p, a type V myosin. In addition, a BUB2-dependent cell cycle checkpoint has been described that inhibits the mitotic exit network and cytokinesis until proper centrosome position is achieved. Combined, these studies provide molecular insight into how cells link cellular polarity, spindle position and cell cycle progression.

scholarly journals Essential Dosage-Dependent Functions of the Transcription Factor Yin Yang 1 in Late Embryonic Development and Cell Cycle Progression

2006 ◽  
Vol 26 (9) ◽  
pp. 3565-3581 ◽  
Author(s):  
El Bachir Affar ◽  
Frédérique Gay ◽  
Yujiang Shi ◽  
Huifei Liu ◽  
Maite Huarte ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Transcription Factor ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Eukaryotic Cell ◽  
Dependent Manner ◽  
Phenotypic Analysis ◽  
Yin Yang 1 ◽  
Yin Yang

ABSTRACT Constitutive ablation of the Yin Yang 1 (YY1) transcription factor in mice results in peri-implantation lethality. In this study, we used homologous recombination to generate knockout mice carrying yy1 alleles expressing various amounts of YY1. Phenotypic analysis of yy1 mutant embryos expressing ∼75%, ∼50%, and ∼25% of the normal complement of YY1 identified a dosage-dependent requirement for YY1 during late embryogenesis. Indeed, reduction of YY1 levels impairs embryonic growth and viability in a dose-dependent manner. Analysis of the corresponding mouse embryonic fibroblast cells also revealed a tight correlation between YY1 dosage and cell proliferation, with a complete ablation of YY1 inducing cytokinesis failure and cell cycle arrest. Consistently, RNA interference-mediated inhibition of YY1 in HeLa cells prevents cytokinesis, causes proliferative arrest, and increases cellular sensitivity to various apoptotic agents. Genome-wide expression profiling identified a plethora of YY1 target genes that have been implicated in cell growth, proliferation, cytokinesis, apoptosis, development, and differentiation, suggesting that YY1 coordinates multiple essential biological processes through a complex transcriptional network. These data not only shed new light on the molecular basis for YY1 developmental roles and cellular functions, but also provide insight into the general mechanisms controlling eukaryotic cell proliferation, apoptosis, and differentiation.

scholarly journals Sub-minute phosphoregulation of cell-cycle systems during Plasmodium gamete formation

2017 ◽  
Author(s):  
Brandon M. Invergo ◽  
Mathieu Brochet ◽  
Lu Yu ◽  
Jyoti Choudhary ◽  
Pedro Beltrao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Kinases ◽  
Cell Biology ◽  
Cell Cycle Progression ◽  
Time Course ◽  
Human Pathogens ◽  
Cellular Functions ◽  
Phenotypic Analysis ◽  
Cycle Systems ◽  
Unbiased Manner

AbstractMalaria parasites are protists of the genus Plasmodium, whose transmission to mosquitoes is initiated by the production of gametes. Male gametogenesis is an extremely rapid process that is tightly controlled to produce eight flagellated microgametes from a single haploid gametocyte within 10 minutes after ingestion by a mosquito. Regulation of the cell cycle is poorly understood in divergent eukaryotes like Plasmodium, where the highly synchronous response of gametocytes to defined chemical and physical stimuli from the mosquito has proved to be a powerful model to identify specific phosphorylation events critical for cell-cycle progression. To reveal the wider network of phosphorylation signalling in a systematic and unbiased manner, we have measured a high-resolution time course of the phosphoproteome of P. berghei gametocytes during the first minute of gametogenesis. The data show an extremely broad response in which distinct cell-cycle events such as initiation of DNA replication and mitosis are rapidly induced and simultaneously regulated. We identify several protein kinases and phosphatases that are likely central in the gametogenesis signalling pathway and validate our analysis by investigating the phosphoproteomes of mutants in two of them, CDPK4 and SRPK1. We show these protein kinases to have distinct influences over the phosphorylation of similar downstream targets that are consistent with their distinct cellular functions, which is revealed by a detailed phenotypic analysis of an SRPK1 mutant. Together, the results show that key cell-cycle systems in Plasmodium undergo simultaneous and rapid phosphoregulation. We demonstrate how a highly resolved time-course of dynamic phosphorylation events can generate deep insights into the unusual cell biology of a divergent eukaryote, which serves as a model for an important group of human pathogens.

scholarly journals The PTEN and ATM axis controls the G1/S cell cycle checkpoint and tumorigenesis in HER2-positive breast cancer

2021 ◽  
Author(s):  
Christian Bassi ◽  
Jerome Fortin ◽  
Bryan E. Snow ◽  
Andrew Wakeham ◽  
Jason Ho ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Physiological Role ◽  
Genotoxic Stress ◽  
Cell Cycle Checkpoint ◽  
Mutant Form ◽  
Her2 Positive ◽  
Her2 Positive Breast Cancer ◽  
Positive Breast Cancer

AbstractThe tumor suppressor PTEN is disrupted in a large proportion of cancers, including in HER2-positive breast cancer, where its loss is associated with resistance to therapy. Upon genotoxic stress, ataxia telangiectasia mutated (ATM) is activated and phosphorylates PTEN on residue 398. To elucidate the physiological role of this molecular event, we generated and analyzed knock-in mice expressing a mutant form of PTEN that cannot be phosphorylated by ATM (PTEN-398A). This mutation accelerated tumorigenesis in a model of HER2-positive breast cancer. Mammary tumors in bi-transgenic mice carrying MMTV-neu and Pten398A were characterized by DNA damage accumulation but reduced apoptosis. Mechanistically, phosphorylation of PTEN at position 398 is essential for the proper activation of the S phase checkpoint controlled by the PI3K–p27Kip1–CDK2 axis. Moreover, we linked these defects to the impaired ability of the PTEN-398A protein to relocalize to the plasma membrane in response to genotoxic stress. Altogether, our results uncover a novel role for ATM-dependent PTEN phosphorylation in the control of genomic stability, cell cycle progression, and tumorigenesis.

scholarly journals Large-scale Chromosomal Movements During Interphase Progression in Drosophila

1998 ◽  
Vol 143 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Amy K. Csink ◽  
Steven Henikoff
Keyword(s):  
Cell Cycle ◽  
Large Scale ◽  
Cell Cycle Progression ◽  
Nuclear Architecture ◽  
Heterochromatic Region ◽  
S Phase ◽  
G1 Phase ◽  
Interphase Chromosome ◽  
Dna Quantitation ◽  
Delayed Maturation

We examined the effect of cell cycle progression on various levels of chromosome organization in Drosophila. Using bromodeoxyuridine incorporation and DNA quantitation in combination with fluorescence in situ hybridization, we detected gross chromosomal movements in diploid interphase nuclei of larvae. At the onset of S-phase, an increased separation was seen between proximal and distal positions of a long chromsome arm. Progression through S-phase disrupted heterochromatic associations that have been correlated with gene silencing. Additionally, we have found that large-scale G1 nuclear architecture is continually dynamic. Nuclei display a Rabl configuration for only ∼2 h after mitosis, and with further progression of G1-phase can establish heterochromatic interactions between distal and proximal parts of the chromosome arm. We also find evidence that somatic pairing of homologous chromosomes is disrupted during S-phase more rapidly for a euchromatic than for a heterochromatic region. Such interphase chromosome movements suggest a possible mechanism that links gene regulation via nuclear positioning to the cell cycle: delayed maturation of heterochromatin during G1-phase delays establishment of a silent chromatin state.

scholarly journals Mutations at sites involved in Suc1 binding inactivate Cdc2.

1991 ◽  
Vol 11 (12) ◽  
pp. 6177-6184 ◽  
Author(s):  
B Ducommun ◽  
P Brambilla ◽  
G Draetta
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Specific Interaction ◽  
Physiological Role ◽  
Negative Effects ◽  
Alanine Scanning Mutagenesis ◽  
Cycle Progression ◽  
Mutant Proteins ◽  
Additional Protein

suc1+ encodes an essential cell cycle regulator of the fission yeast Schizosaccharomyces pombe. Its product, a 13-kDa protein, interacts with the Cdc2 protein kinase. Both positive and negative effects on cell cycle progression have been attributed to Suc1. To date, the exact mechanisms and the physiological role of the interaction between Suc1 and Cdc2 remain unclear. Here we have studied the molecular basis of this association. We show that Cdc2 can bind Suc1 or its mammalian homolog directly in the absence of any additional protein component. Using an alanine scanning mutagenesis method, we analyzed the interaction between Cdc2 and Suc1. We show that the integrity of several domains on the Cdc2 protein, including sites directly involved in catalytic activity, is required for binding to Suc1. Furthermore, Cdc2 mutant proteins unable to bind Suc1 (but able to bind cyclins) are nonfunctional when overexpressed in S. pombe, indicating that a specific interaction with Suc1 is required for Cdc2 function.

The THAP–zinc finger protein THAP1 regulates endothelial cell proliferation through modulation of pRB/E2F cell-cycle target genes

Blood ◽  
2006 ◽  
Vol 109 (2) ◽  
pp. 584-594 ◽  
Author(s):  
Corinne Cayrol ◽  
Chrystelle Lacroix ◽  
Catherine Mathe ◽  
Vincent Ecochard ◽  
Michele Ceribelli ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Large Scale ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Zinc Finger Protein ◽  
Endothelial Cell Proliferation ◽  
Cycle Progression ◽  
Transcriptional Target

Abstract We recently cloned a novel human nuclear factor (designated THAP1) from postcapillary venule endothelial cells (ECs) that contains a DNA-binding THAP domain, shared with zebrafish E2F6 and several Caenorhabditis elegans proteins interacting genetically with retinoblastoma gene product (pRB). Here, we show that THAP1 is a physiologic regulator of EC proliferation and cell-cycle progression, 2 essential processes for angiogenesis. Retroviral-mediated gene transfer of THAP1 into primary human ECs inhibited proliferation, and large-scale expression profiling with microarrays revealed that THAP1-mediated growth inhibition is due to coordinated repression of pRB/E2F cell-cycle target genes. Silencing of endogenous THAP1 through RNA interference similarly inhibited EC proliferation and G1/S cell-cycle progression, and resulted in down-regulation of several pRB/E2F cell-cycle target genes, including RRM1, a gene required for S-phase DNA synthesis. Chromatin immunoprecipitation assays in proliferating ECs showed that endogenous THAP1 associates in vivo with a consensus THAP1-binding site found in the RRM1 promoter, indicating that RRM1 is a direct transcriptional target of THAP1. The similar phenotypes observed after THAP1 overexpression and silencing suggest that an optimal range of THAP1 expression is essential for EC proliferation. Together, these data provide the first links in mammals among THAP proteins, cell proliferation, and pRB/E2F cell-cycle pathways.

scholarly journals The Lon protease temporally restricts polar cell differentiation events during the Caulobacter cell cycle

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Deike J Omnus ◽  
Matthias J Fink ◽  
Klaudia Szwedo ◽  
Kristina Jonas
Keyword(s):  
Cell Cycle ◽  
Cell Differentiation ◽  
Protein Function ◽  
Cell Cycle Progression ◽  
Protein Quality ◽  
Caulobacter Crescentus ◽  
Critical Role ◽  
Cycle Phase ◽  
Polar Cell

The highly conserved protease Lon has important regulatory and protein quality control functions in cells from the three domains of life. Despite many years of research on Lon, only a few specific protein substrates are known in most organisms. Here, we used a quantitative proteomics approach to identify novel substrates of Lon in the dimorphic bacterium Caulobacter crescentus. We focused our study on proteins involved in polar cell differentiation and investigated the developmental regulator StaR and the flagella hook length regulator FliK as specific Lon substrates in detail. We show that Lon recognizes these proteins at their C-termini, and that Lon-dependent degradation ensures their temporally restricted accumulation in the cell cycle phase when their function is needed. Disruption of this precise temporal regulation of StaR and FliK levels in a Δlon mutant contributes to defects in stalk biogenesis and motility, respectively, revealing a critical role of Lon in coordinating developmental processes with cell cycle progression. Our work underscores the importance of Lon in the regulation of complex temporally controlled processes by adjusting the concentrations of critical regulatory proteins. Furthermore, this study includes the first characterization of FliK in C. crescentus and uncovers a dual role of the C-terminal amino acids of FliK in protein function and degradation.

scholarly journals The PHD Domain of Np95 (mUHRF1) Is Involved in Large-Scale Reorganization of Pericentromeric Heterochromatin

2008 ◽  
Vol 19 (8) ◽  
pp. 3554-3563 ◽  
Author(s):  
Roberto Papait ◽  
Christian Pistore ◽  
Ursula Grazini ◽  
Federica Babbio ◽  
Sara Cogliati ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Large Scale ◽  
Cell Cycle Progression ◽  
Expression Patterns ◽  
Pericentromeric Heterochromatin ◽  
Proliferating Cells ◽  
Cycle Progression ◽  
Dynamic Structures ◽  
Phd Domain

Heterochromatic chromosomal regions undergo large-scale reorganization and progressively aggregate, forming chromocenters. These are dynamic structures that rapidly adapt to various stimuli that influence gene expression patterns, cell cycle progression, and differentiation. Np95-ICBP90 (m- and h-UHRF1) is a histone-binding protein expressed only in proliferating cells. During pericentromeric heterochromatin (PH) replication, Np95 specifically relocalizes to chromocenters where it highly concentrates in the replication factories that correspond to less compacted DNA. Np95 recruits HDAC and DNMT1 to PH and depletion of Np95 impairs PH replication. Here we show that Np95 causes large-scale modifications of chromocenters independently from the H3:K9 and H4:K20 trimethylation pathways, from the expression levels of HP1, from DNA methylation and from the cell cycle. The PHD domain is essential to induce this effect. The PHD domain is also required in vitro to increase access of a restriction enzyme to DNA packaged into nucleosomal arrays. We propose that the PHD domain of Np95-ICBP90 contributes to the opening and/or stabilization of dense chromocenter structures to support the recruitment of modifying enzymes, like HDAC and DNMT1, required for the replication and formation of PH.

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