scholarly journals CDK phosphorylation of SLD-2 is required for replication initiation and germline development in C. elegans

2014 ◽  
Vol 204 (4) ◽  
pp. 507-522 ◽  
Author(s):  
Vincent Gaggioli ◽  
Eva Zeiser ◽  
David Rivers ◽  
Charles R. Bradshaw ◽  
Julie Ahringer ◽  
...  
Keyword(s):  
Vital Role ◽  
Replication Initiation ◽  
Cyclin Dependent Kinase ◽  
Germline Development ◽  
Nuclear Retention ◽  
C Elegans ◽  
Essential Function ◽  
Cdk Phosphorylation ◽  
Nematode Worm

Cyclin-dependent kinase (CDK) plays a vital role in proliferation control across eukaryotes. Despite this, how CDK mediates cell cycle and developmental transitions in metazoa is poorly understood. In this paper, we identify orthologues of Sld2, a CDK target that is important for DNA replication in yeast, and characterize SLD-2 in the nematode worm Caenorhabditis elegans. We demonstrate that SLD-2 is required for replication initiation and the nuclear retention of a critical component of the replicative helicase CDC-45 in embryos. SLD-2 is a CDK target in vivo, and phosphorylation regulates the interaction with another replication factor, MUS-101. By mutation of the CDK sites in sld-2, we show that CDK phosphorylation of SLD-2 is essential in C. elegans. Finally, using a phosphomimicking sld-2 mutant, we demonstrate that timely CDK phosphorylation of SLD-2 is an important control mechanism to allow normal proliferation in the germline. These results determine an essential function of CDK in metazoa and identify a developmental role for regulated SLD-2 phosphorylation.

scholarly journals CDK phosphorylation of SLD-2 is required for replication initiation and germline development in C. elegans

2014 ◽  
Vol 204 (6) ◽  
pp. 1075-1075
Author(s):  
Vincent Gaggioli ◽  
Eva Zeiser ◽  
David Rivers ◽  
Charles R. Bradshaw ◽  
Julie Ahringer ◽  
...  
Keyword(s):  
Replication Initiation ◽  
Germline Development ◽  
C Elegans ◽  
Cdk Phosphorylation

scholarly journals Visualizing the metazoan proliferation-terminal differentiation decision in vivo

2019 ◽  
Author(s):  
Rebecca C. Adikes ◽  
Abraham Q. Kohrman ◽  
Michael A. Q. Martinez ◽  
Nicholas J. Palmisano ◽  
Jayson J. Smith ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Control ◽  
Cell Lineage ◽  
Terminal Differentiation ◽  
Cyclin Dependent Kinase ◽  
C Elegans ◽  
Differentiated Cells ◽  
Imaging Tool ◽  
Wide Range

SummaryCell proliferation and terminal differentiation are intimately coordinated during metazoan development. Here, we adapt a cyclin-dependent kinase (CDK) sensor to uncouple these cell cycle-associated events live in C. elegans and zebrafish. The CDK sensor consists of a fluorescently tagged CDK substrate that steadily translocates from the nucleus to the cytoplasm in response to increasing CDK activity and consequent sensor phosphorylation. We show that the CDK sensor can distinguish cycling cells in G1 from terminally differentiated cells in G0, revealing a commitment point and a cryptic stochasticity in an otherwise invariant C. elegans cell lineage. We also derive a predictive model of future proliferation behavior in C. elegans and zebrafish based on a snapshot of CDK activity in newly born cells. Thus, we introduce a live-cell imaging tool to facilitate in vivo studies of cell cycle control in a wide-range of developmental contexts.

scholarly journals Identification of the critical replication targets of CDK reveals direct regulation of replication initiation factors by the embryo polarity machinery in C. elegans

PLoS Genetics ◽  
2020 ◽  
Vol 16 (12) ◽  
pp. e1008948
Author(s):  
Vincent Gaggioli ◽  
Manuela R. Kieninger ◽  
Anna Klucnika ◽  
Richard Butler ◽  
Philip Zegerman
Keyword(s):  
Direct Interaction ◽  
Early Embryo ◽  
S Phase ◽  
Replication Initiation ◽  
Dna Replication Initiation ◽  
C Elegans ◽  
Initiation Factors ◽  
Physiological Importance ◽  
Essential Function ◽  
Phase Length

During metazoan development, the cell cycle is remodelled to coordinate proliferation with differentiation. Developmental cues cause dramatic changes in the number and timing of replication initiation events, but the mechanisms and physiological importance of such changes are poorly understood. Cyclin-dependent kinases (CDKs) are important for regulating S-phase length in many metazoa, and here we show in the nematode Caenorhabditis elegans that an essential function of CDKs during early embryogenesis is to regulate the interactions between three replication initiation factors SLD-3, SLD-2 and MUS-101 (Dpb11/TopBP1). Mutations that bypass the requirement for CDKs to generate interactions between these factors is partly sufficient for viability in the absence of Cyclin E, demonstrating that this is a critical embryonic function of this Cyclin. Both SLD-2 and SLD-3 are asymmetrically localised in the early embryo and the levels of these proteins inversely correlate with S-phase length. We also show that SLD-2 asymmetry is determined by direct interaction with the polarity protein PKC-3. This study explains an essential function of CDKs for replication initiation in a metazoan and provides the first direct molecular mechanism through which polarization of the embryo is coordinated with DNA replication initiation factors.

scholarly journals Roles of the CDK Phosphorylation Sites of Yeast Cdc6 in Chromatin Binding and Rereplication

2007 ◽  
Vol 18 (4) ◽  
pp. 1324-1336 ◽  
Author(s):  
Sangeet Honey ◽  
Bruce Futcher
Keyword(s):  
Nuclear Import ◽  
Replication Initiation ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Chromatin Binding ◽  
Wild Type ◽  
Mcm Proteins ◽  
Cdk Phosphorylation ◽  
Replication Initiation Proteins ◽  
Dominant Lethality

The Saccharomyces cerevisiae Cdc6 protein is crucial for DNA replication. In the absence of cyclin-dependent kinase (CDK) activity, Cdc6 binds to replication origins, and loads Mcm proteins. In the presence of CDK activity, Cdc6 does not bind to origins, and this helps prevent rereplication. CDK activity affects Cdc6 function by multiple mechanisms: CDK activity affects transcription of CDC6, degradation of Cdc6, nuclear import of Cdc6, and binding of Cdc6 to Clb2. Here we examine some of these mechanisms individually. We find that when Cdc6 is forced into the nucleus during late G1 or S, it will not substantially reload onto chromatin no matter whether its CDK sites are present or not. In contrast, at a G2/M nocodazole arrest, Cdc6 will reload onto chromatin if and only if its CDK sites have been removed. Trace amounts of nonphosphorylatable Cdc6 are dominant lethal in strains bearing nonphosphorylatable Orc2 and Orc6, apparently because of rereplication. This synthetic dominant lethality occurs even in strains with wild-type MCM genes. Nonphosphorylatable Cdc6, or Orc2 and Orc6, sensitize cells to rereplication caused by overexpression of various replication initiation proteins such as Dpb11 and Sld2.

scholarly journals Role of misfolded tau in the onset and progression of brain toxicity after trauma

2020 ◽  
Author(s):  
Luisa Diomede ◽  
Elisa R. Zanier ◽  
Maria Monica Barzago ◽  
Gloria Vegliante ◽  
Margherita Romeo ◽  
...  
Keyword(s):  
Mouse Model ◽  
Transgenic Mice ◽  
Functional Decline ◽  
Vital Role ◽  
Misfolded Proteins ◽  
Tau Pathology ◽  
Knock Out ◽  
C Elegans

Abstract Background Traumatic brain injury (TBI) is associated with widespread tau pathology in about thirty percent of patients surviving late after injury. We previously found that TBI in mice induces a transmissible tau pathology (tauTBI), with late cognitive decline and synaptic dysfunction. However, it is not clear whether tauTBI is a marker of ongoing neurodegeneration or a driver of functional decline. We employed the nematode C. elegans, which can recognize pathogenic forms of misfolded proteins, to investigate whether tauTBI is the primary toxic culprit in post-TBI neurodegeneration. Methods We developed an original approach involving the administration of brain homogenates from TBI mice to C. elegans, a valuable model for rapidly investigating the pathogenic effects of misfolded proteins in vivo. Brain homogenates from transgenic mice overexpressing tau P301L, a tauopathy mouse model, as well as pre-aggregated recombinant tau were employed to test whether abnormal tau conformers play a causal role in driving toxicity in TBI. Results Worms given brain homogenates from chronic but not acute TBI mice, or from mice in which tauTBI had been transmitted by intracerebral inoculation, had impaired motility and neuromuscular synaptic transmission. Results were similar when worms were exposed to brain homogenates from transgenic mice overexpressing tau P301L, a tauopathy mouse model, suggesting that TBI-induced and mutant tau have similar toxic properties. Harsh protease digestion to eliminate the protein component of the homogenates or pre-incubation with anti-tau antibodies abolished the toxicity. Homogenates of chronic TBI brains from tau knock-out mice were not toxic to C. elegans, whereas pre-aggregated recombinant tau was sufficient to impair their motility. Conclusions These results support a vital role of abnormal tau species in chronic neurodegeneration after TBI supporting the idea that targeting pathological tau may point to a therapeutic opportunity in trauma, and set the groundwork for the development of a C. elegans-based platform for screening anti-tau compounds.

scholarly journals SET-9 and SET-26 are H3K4me3 readers and play critical roles in germline development and longevity

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Wenke Wang ◽  
Amaresh Chaturbedi ◽  
Minghui Wang ◽  
Serim An ◽  
Satheeja Santhi Velayudhan ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Response ◽  
Binding Sites ◽  
Target Genes ◽  
Germline Development ◽  
Heat Stress Response ◽  
C Elegans ◽  
Redundant Functions

C. elegans SET-9 and SET-26 are highly homologous paralogs that share redundant functions in germline development, but SET-26 alone plays a key role in longevity and heat stress response. Whereas SET-26 is broadly expressed, SET-9 is only detectable in the germline, which likely accounts for their different biological roles. SET-9 and SET-26 bind to H3K4me3 with adjacent acetylation marks in vitro and in vivo. In the soma, SET-26 acts through DAF-16 to modulate longevity. In the germline, SET-9 and SET-26 restrict H3K4me3 domains around SET-9 and SET-26 binding sites, and regulate the expression of specific target genes, with critical consequence on germline development. SET-9 and SET-26 are highly conserved and our findings provide new insights into the functions of these H3K4me3 readers in germline development and longevity.

scholarly journals Host CDK-1 and formin mediate microvillar effacement induced by enterohemorrhagic Escherichia coli

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cheng-Rung Huang ◽  
Cheng-Ju Kuo ◽  
Chih-Wen Huang ◽  
Yu-Ting Chen ◽  
Bang-Yu Liu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Intestinal Cell ◽  
Intestinal Cells ◽  
Cyclin Dependent Kinase ◽  
C Elegans ◽  
Mitotic Cyclin ◽  
Human Intestinal Cells

AbstractEnterohemorrhagic Escherichia coli (EHEC) induces changes to the intestinal cell cytoskeleton and formation of attaching and effacing lesions, characterized by the effacement of microvilli and then formation of actin pedestals to which the bacteria are tightly attached. Here, we use a Caenorhabditis elegans model of EHEC infection to show that microvillar effacement is mediated by a signalling pathway including mitotic cyclin-dependent kinase 1 (CDK1) and diaphanous-related formin 1 (CYK1). Similar observations are also made using EHEC-infected human intestinal cells in vitro. Our results support the use of C. elegans as a host model for studying attaching and effacing lesions in vivo, and reveal that the CDK1-formin signal axis is necessary for EHEC-induced microvillar effacement.

scholarly journals Saccharomyces cerevisiae Ime2 phosphorylates Sic1 at multiple PXS/T sites but is insufficient to trigger Sic1 degradation

2006 ◽  
Vol 399 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Chantelle Sedgwick ◽  
Matthew Rawluk ◽  
James Decesare ◽  
Sheetal Raithatha ◽  
James Wohlschlegel ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Phase Boundary ◽  
S Phase ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Proliferating Cells ◽  
Initiation Of Dna Replication ◽  
Cdk Phosphorylation

The initiation of DNA replication in Saccharomyces cerevisiae depends upon the destruction of the Clb–Cdc28 inhibitor Sic1. In proliferating cells Cln–Cdc28 complexes phosphorylate Sic1, which stimulates binding of Sic1 to SCFCdc4 and triggers its proteosome mediated destruction. During sporulation cyclins are not expressed, yet Sic1 is still destroyed at the G1-/S-phase boundary. The Cdk (cyclin dependent kinase) sites are also required for Sic1 destruction during sporulation. Sic1 that is devoid of Cdk phosphorylation sites displays increased stability and decreased phosphorylation in vivo. In addition, we found that Sic1 was modified by ubiquitin in sporulating cells and that SCFCdc4 was required for this modification. The meiosis-specific kinase Ime2 has been proposed to promote Sic1 destruction by phosphorylating Sic1 in sporulating cells. We found that Ime2 phosphorylates Sic1 at multiple sites in vitro. However, only a subset of these sites corresponds to Cdk sites. The identification of multiple sites phosphorylated by Ime2 has allowed us to propose a motif for phosphorylation by Ime2 (PXS/T) where serine or threonine acts as a phospho-acceptor. Although Ime2 phosphorylates Sic1 at multiple sites in vitro, the modified Sic1 fails to bind to SCFCdc4. In addition, the expression of Ime2 in G1 arrested haploid cells does not promote the destruction of Sic1. These data support a model where Ime2 is necessary but not sufficient to promote Sic1 destruction during sporulation.

scholarly journals Cyclin-Dependent Kinase-Dependent Phosphorylation of Sox2 at Serine 39 Regulates Neurogenesis

2017 ◽  
Vol 37 (16) ◽  
Author(s):  
Shuhui Lim ◽  
Akshay Bhinge ◽  
Sara Bragado Alonso ◽  
Irene Aksoy ◽  
Julieta Aprea ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Neuronal Differentiation ◽  
Kinase Activity ◽  
Phosphorylation Site ◽  
Cyclin Dependent Kinase ◽  
Truncated Form ◽  
Self Renewal ◽  
Cdk Phosphorylation

ABSTRACT Sox2 is known to be important for neuron formation, but the precise mechanism through which it activates a neurogenic program and how this differs from its well-established function in self-renewal of stem cells remain elusive. In this study, we identified a highly conserved cyclin-dependent kinase (Cdk) phosphorylation site on serine 39 (S39) in Sox2. In neural stem cells (NSCs), phosphorylation of S39 enhances the ability of Sox2 to negatively regulate neuronal differentiation, while loss of phosphorylation is necessary for chromatin retention of a truncated form of Sox2 generated during neurogenesis. We further demonstrated that nonphosphorylated cleaved Sox2 specifically induces the expression of proneural genes and promotes neurogenic commitment in vivo. Our present study sheds light on how the level of Cdk kinase activity directly regulates Sox2 to tip the balance between self-renewal and differentiation in NSCs.

scholarly journals Phosphorylation of Sic1, a Cyclin-dependent Kinase (Cdk) Inhibitor, by Cdk Including Pho85 Kinase Is Required for Its Prompt Degradation

1998 ◽  
Vol 9 (9) ◽  
pp. 2393-2405 ◽  
Author(s):  
Masafumi Nishizawa ◽  
Masaoki Kawasumi ◽  
Marie Fujino ◽  
Akio Toh-e
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Cdk Inhibitor ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cdk Phosphorylation ◽  
Cdc28 Kinase

In the yeast Saccharomyces cerevisiae, Sic1, an inhibitor of Clb-Cdc28 kinases, must be phosphorylated and degraded in G1for cells to initiate DNA replication, and Cln-Cdc28 kinase appears to be primarily responsible for phosphorylation of Sic1. The Pho85 kinase is a yeast cyclin-dependent kinase (Cdk), which is not essential for cell growth unless both CLN1 andCLN2 are absent. We demonstrate that Pho85, when complexed with Pcl1, a G1cyclin homologue, can phosphorylate Sic1 in vitro, and that Sic1 appears to be more stable inpho85Δ cells. Three consensus Cdk phosphorylation sites present in Sic1 are phosphorylated in vivo, and two of them are required for prompt degradation of the inhibitor. Pho85 and other G1Cdks appear to phosphorylate Sic1 at different sites in vivo. Thus at least two distinct Cdks can participate in phosphorylation of Sic1 and may therefore regulate progression through G1.

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