scholarly journals Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress

2021 ◽  
Vol 9 (10) ◽  
pp. 2152
Author(s):  
Brittany Friedson ◽  
Katrina F. Cooper
Keyword(s):  
Cell Death ◽  
Rna Polymerase Ii ◽  
Cell Fate ◽  
Ubiquitin Proteasome System ◽  
Mitochondrial Morphology ◽  
Atp Production ◽  
Cell Fate Decisions ◽  
Regulated Cell Death ◽  
Cyclin C ◽  
Convergence Point

The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways.

scholarly journals Cryo-EM structural analysis of FADD:Caspase-8 complexes defines the catalytic dimer architecture for co-ordinated control of cell fate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joanna L. Fox ◽  
Michelle A. Hughes ◽  
Xin Meng ◽  
Nikola A. Sarnowska ◽  
Ian R. Powley ◽  
...  
Keyword(s):  
Cell Death ◽  
Structural Analysis ◽  
Cell Fate ◽  
Catalytic Domain ◽  
Caspase 8 ◽  
Type I ◽  
Signaling Complex ◽  
Catalytic Domains ◽  
Regulated Cell Death ◽  
Death Effector

AbstractRegulated cell death is essential in development and cellular homeostasis. Multi-protein platforms, including the Death-Inducing Signaling Complex (DISC), co-ordinate cell fate via a core FADD:Caspase-8 complex and its regulatory partners, such as the cell death inhibitor c-FLIP. Here, using electron microscopy, we visualize full-length procaspase-8 in complex with FADD. Our structural analysis now reveals how the FADD-nucleated tandem death effector domain (tDED) helical filament is required to orientate the procaspase-8 catalytic domains, enabling their activation via anti-parallel dimerization. Strikingly, recruitment of c-FLIPS into this complex inhibits Caspase-8 activity by altering tDED triple helix architecture, resulting in steric hindrance of the canonical tDED Type I binding site. This prevents both Caspase-8 catalytic domain assembly and tDED helical filament elongation. Our findings reveal how the plasticity, composition and architecture of the core FADD:Caspase-8 complex critically defines life/death decisions not only via the DISC, but across multiple key signaling platforms including TNF complex II, the ripoptosome, and RIPK1/RIPK3 necrosome.

scholarly journals Fatty Acids Metabolism: The Bridge Between Ferroptosis and Ionizing Radiation

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhu-hui Yuan ◽  
Tong Liu ◽  
Hao Wang ◽  
Li-xiang Xue ◽  
Jun-jie Wang
Keyword(s):  
Fatty Acids ◽  
Cell Death ◽  
Ionizing Radiation ◽  
Cell Fate ◽  
Tumor Response ◽  
Cell Fate Decisions ◽  
Current Review ◽  
Pathway Crosstalk ◽  
Fatty Acids Metabolism ◽  
Molecular Signals

Exposure of tumor cells to ionizing radiation (IR) alters the microenvironment, particularly the fatty acid (FA) profile and activity. Moreover, abnormal FA metabolism, either catabolism or anabolism, is essential for synthesizing biological membranes and delivering molecular signals to induce ferroptotic cell death. The current review focuses on the bistable regulation characteristics of FA metabolism and explains how FA catabolism and anabolism pathway crosstalk harmonize different ionizing radiation-regulated ferroptosis responses, resulting in pivotal cell fate decisions. In summary, targeting key molecules involved in lipid metabolism and ferroptosis may amplify the tumor response to IR.

scholarly journals AtNSE1 and AtNSE3 are required for embryo pattern formation and maintenance of cell viability during Arabidopsis embryogenesis

2019 ◽  
Vol 70 (21) ◽  
pp. 6229-6244
Author(s):  
Gang Li ◽  
Wenxuan Zou ◽  
Liufang Jian ◽  
Jie Qian ◽  
Jie Zhao
Keyword(s):  
Cell Death ◽  
Cell Viability ◽  
Cell Fate ◽  
Embryo Development ◽  
Higher Plants ◽  
Early Embryo ◽  
Embryo Cell ◽  
Early Embryogenesis ◽  
Embryo Abortion ◽  
Cell Fate Decisions

Abstract Embryogenesis is an essential process during seed development in higher plants. It has previously been shown that mutation of the Arabidopsis non-SMC element genes AtNSE1 or AtNSE3 leads to early embryo abortion, and their proteins can interact with each other directly. However, the crucial regions of these proteins in this interaction and how the proteins are cytologically involved in Arabidopsis embryo development are unknown. In this study, we found that the C-terminal including the Ring-like motif of AtNSE1 can interact with the N-terminal of AtNSE3, and only the Ring-like motif is essential for binding with three α motifs of AtNSE2 (homologous to AtMMS21). Using genetic assays and by analysing molecular markers of cell fate decisions (STM, WOX5, and WOX8) in mutant nse1 and nse3 embryos, we found that AtNSE1 and AtNSE3 work non-redundantly in early embryo development, and that differentiation of the apical meristem and the hypophysis fails in the mutants, which have disrupted auxin transportation and responses. However, the upper cells of the suspensor in the mutants seem to have proper embryo cell identity. Cytological examination showed that cell death occurred from the early embryo stage, and that vacuolar programmed cell death and necrosis in the nse1 and nse3 mutant embryos led to ovule abortion. Thus, AtNSE1 and AtNSE3 are essential for maintaining cell viability and growth during early embryogenesis. Our results improve our understanding of the functions of SMC5/6 complex in early embryogenesis in Arabidopsis.

scholarly journals Ferroptosis and Cancer: Mitochondria Meet the “Iron Maiden” Cell Death

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1505 ◽  
Author(s):  
Anna Martina Battaglia ◽  
Roberta Chirillo ◽  
Ilenia Aversa ◽  
Alessandro Sacco ◽  
Francesco Costanzo ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Morphology ◽  
Oxygen Species ◽  
Severe Damage ◽  
Master Regulators ◽  
Regulated Cell Death ◽  
New Strategy ◽  
Metabolic Imbalance ◽  
New Type

Ferroptosis is a new type of oxidative regulated cell death (RCD) driven by iron-dependent lipid peroxidation. As major sites of iron utilization and master regulators of oxidative metabolism, mitochondria are the main source of reactive oxygen species (ROS) and, thus, play a role in this type of RCD. Ferroptosis is, indeed, associated with severe damage in mitochondrial morphology, bioenergetics, and metabolism. Furthermore, dysregulation of mitochondrial metabolism is considered a biochemical feature of neurodegenerative diseases linked to ferroptosis. Whether mitochondrial dysfunction can, per se, initiate ferroptosis and whether mitochondrial function in ferroptosis is context-dependent are still under debate. Cancer cells accumulate high levels of iron and ROS to promote their metabolic activity and growth. Of note, cancer cell metabolic rewiring is often associated with acquired sensitivity to ferroptosis. This strongly suggests that ferroptosis may act as an adaptive response to metabolic imbalance and, thus, may constitute a new promising way to eradicate malignant cells. Here, we review the current literature on the role of mitochondria in ferroptosis, and we discuss opportunities to potentially use mitochondria-mediated ferroptosis as a new strategy for cancer therapy.

scholarly journals RIP1-dependent linear and nonlinear recruitments of caspase-8 and RIP3 respectively to necrosome specify distinct cell death outcomes

2021 ◽  
Author(s):  
Xiang Li ◽  
Chuan-Qi Zhong ◽  
Rui Wu ◽  
Xiaozheng Xu ◽  
Zhang-Hua Yang ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Fate ◽  
Basis Sets ◽  
Nonlinear Dependence ◽  
Caspase 8 ◽  
Cell Fate Decisions ◽  
Distinct Cell ◽  
Quantitative Understanding ◽  
Linear And Nonlinear ◽  
Dynamic Interplay

AbstractThere remains a significant gap in our quantitative understanding of crosstalk between apoptosis and necroptosis pathways. By employing the SWATH-MS technique, we quantified absolute amounts of up to thousands of proteins in dynamic assembling/de-assembling of TNF signaling complexes. Combining SWATH-MS-based network modeling and experimental validation, we found that when RIP1 level is below ~1000 molecules/cell (mpc), the cell solely undergoes TRADD-dependent apoptosis. When RIP1 is above ~1000 mpc, pro-caspase-8 and RIP3 are recruited to necrosome respectively with linear and nonlinear dependence on RIP1 amount, which well explains the co-occurrence of apoptosis and necroptosis and the paradoxical observations that RIP1 is required for necroptosis but its increase down-regulates necroptosis. Higher amount of RIP1 (>~46,000 mpc) suppresses apoptosis, leading to necroptosis alone. The relation between RIP1 level and occurrence of necroptosis or total cell death is biphasic. Our study provides a resource for encoding the complexity of TNF signaling and a quantitative picture how distinct dynamic interplay among proteins function as basis sets in signaling complexes, enabling RIP1 to play diverse roles in governing cell fate decisions.

scholarly journals Pkh1p-Ypk1p and Pkh1p-Sch9p Pathways Are Activated by Acetic Acid to Induce a Mitochondrial-Dependent Regulated Cell Death

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
António Rego ◽  
Filipa Mendes ◽  
Vítor Costa ◽  
Susana Rodrigues Chaves ◽  
Manuela Côrte-Real
Keyword(s):  
Cell Death ◽  
Acetic Acid ◽  
Cell Survival ◽  
Cell Fate ◽  
Negative Regulator ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Outer Membrane Permeabilization ◽  
Double Deletion ◽  
Regulated Cell Death ◽  
Single Deletion

The yeast Saccharomyces cerevisiae undergoes a mitochondrial-dependent regulated cell death (RCD) exhibiting typical markers of mammalian apoptosis. We have previously shown that ceramide production contributes to RCD induced by acetic acid and is involved in mitochondrial outer membrane permeabilization and cytochrome c release, especially through hydrolysis of complex sphingolipids catalyzed by Isc1p. Recently, we also showed that Sch9p regulates the translocation of Isc1p from the endoplasmic reticulum into mitochondria, perturbing sphingolipid balance and determining cell fate. In this study, we addressed the role of other signaling proteins in acetic acid-induced RCD. We found that single deletion of PKH1 or YPK1, as shown for SCH9 and ISC1, leads to an increase in cell survival in response to acetic acid and that Pkh1/2p-dependent phosphorylation of Ypk1p and Sch9p increases under these conditions. These results indicate that Pkh1p regulates acetic acid-induced RCD through Ypk1p and Sch9p. In addition, our results suggest that Pkh1p-Ypk1p is necessary for isc1Δ resistance to acetic acid-induced RCD. Moreover, double deletion of ISC1 and PKH1 has a drastic effect on cell survival associated with increased ROS accumulation and release of cytochrome c, which is counteracted by overexpression of the PKA pathway negative regulator PDE2. Overall, our results suggest that Pkh1p-Ypk1p and Pkh1p-Sch9p pathways contribute to RCD induced by acetic acid.

scholarly journals Cellular remodeling and JAK inhibition promote zygotic gene expression in the Ciona germline

2021 ◽  
Author(s):  
Naoyuki Ohta ◽  
Lionel Christiaen
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Cell Fate ◽  
Primordial Germ Cells ◽  
Transcription Control ◽  
Cell Fate Decisions ◽  
Fate Specification ◽  
Zygotic Transcription ◽  
General Inhibitor ◽  
Zygotic Gene

During development, remodeling of the cellular transcriptome and proteome underlies cell fate decisions and, in somatic lineages, transcription control is a major determinant of fateful biomolecular transitions. By contrast, early germline fate specification in numerous vertebrate and invertebrate species relies extensively on RNA-level regulation, exerted on asymmetrically inherited maternal supplies, with little-to-no zygotic transcription. However delayed, a maternal-to-zygotic transition is nevertheless poised to complete the deployment of pre-gametic programs in the germline. Here, we focused on early germline specification in the tunicate Ciona to study zygotic genome activation. We first demonstrate that a peculiar cellular remodeling event excludes localized postplasmic mRNAs, including Pem-1, which encodes the general inhibitor of transcription. Subsequently, zygotic transcription begins in Pem-1-negative primordial germ cells (PGCs), as revealed by histochemical detection of elongating RNA Polymerase II (RNAPII), and nascent transcripts from the Mef2 locus. Using PGC-specific Mef2 transcription as a read-out, we uncovered a provisional antagonism between JAK and MEK/BMPRI/GSK3 signaling, which controls the onset of zygotic gene expression, following cellular remodeling of PGC progenitor cells. We propose a 2-step model for the onset of zygotic transcription in the Ciona germline, which relies on successive cellular remodeling and JAK inhibition, and discuss the significance of germ plasm dislocation and remodeling in the context of developmental fate specification.

scholarly journals Multiplexed biochemical imaging reveals caspase activation patterns underlying single cell fate

2018 ◽  
Author(s):  
Maximilian W. Fries ◽  
Kalina T. Haas ◽  
Suzan Ber ◽  
John Saganty ◽  
Emma K. Richardson ◽  
...  
Keyword(s):  
Cell Death ◽  
Single Cell ◽  
Cell Fate ◽  
Genetic Heterogeneity ◽  
Cellular Response ◽  
Single Cells ◽  
Caspase Activation ◽  
Cell Fate Decisions ◽  
Network Activation ◽  
Biochemical Imaging

The biochemical activities underlying cell-fate decisions vary profoundly even in genetically identical cells. But such non-genetic heterogeneity remains refractory to current imaging methods, because their capacity to monitor multiple biochemical activities in single living cells over time remains limited1. Here, we deploy a family of newly designed GFP-like sensors (NyxBits) with fast photon-counting electronics and bespoke analytics (NyxSense) in multiplexed biochemical imaging, to define a network determining the fate of single cells exposed to the DNA-damaging drug cisplatin. By simultaneously imaging a tri-nodal network comprising the cell-death proteases Caspase-2, -3 and -92, we reveal unrecognized single-cell heterogeneities in the dynamics and amplitude of caspase activation that signify survival versus cell death via necrosis or apoptosis. Non-genetic heterogeneity in the pattern of caspase activation recapitulates traits of therapy resistance previously ascribed solely to genetic causes3,4. Chemical inhibitors that alter these patterns can modulate in a predictable manner the phenotypic landscape of the cellular response to cisplatin. Thus, multiplexed biochemical imaging reveals cellular populations and biochemical states, invisible to other methods, underlying therapeutic responses to an anticancer drug. Our work develops widely applicable tools to monitor the dynamic activation of biochemical networks at single-cell resolution. It highlights the necessity to resolve patterns of network activation in single cells, rather than the average state of individual nodes, to define, and potentially control, mechanisms underlying cellular decisions in health and disease.

scholarly journals At a Crossroads to Cancer: How p53-induced Cell Fate Decisions Secure Genome Integrity

2021 ◽  
Author(s):  
Dario Rizzotto ◽  
Lukas Englmaier ◽  
Andreas Villunger
Keyword(s):  
Cell Death ◽  
Cell Fate ◽  
Target Genes ◽  
Nuclear Translocation ◽  
Current Knowledge ◽  
Cellular Transformation ◽  
Model Systems ◽  
Specific Cell ◽  
Cell Type ◽  
Cell Fate Decisions

P53 is known as the most critical tumor suppressor and is often referred to as the guardian of our genome. More than 40 years after its discovery, we are still struggling to understand all molecular details on how this transcription factor prevents oncogenesis or how to leverage current knowledge about its function to improve cancer treatment. Multiple cues, including DNA-damage or mitotic errors, can lead to the stabilization and nuclear translocation of p53, initiating the expression of multiple target genes. These transcriptional programs may well be cell type and stimulus-specific, as is their outcome that ultimately imposes a barrier to cellular transformation. Cell cycle arrest and cell death are two well-studied consequences of p53 activation, but, while being considered as critical, they do not fully explain the consequences of p53 loss-of-function phenotypes in cancer. Here, we discuss how mitotic errors alert the p53 network and give an overview on multiple ways how p53 can trigger cell death. We argue that a comparative analysis of different types of p53 responses, elicited by different triggers in a time-resolved manner in well-defined model systems is critical to understand cell type specific cell fate induced by p53 upon its activation, in order to resolve the remaining mystery of its tumor suppressive function.

scholarly journals Bavachin Induces Ferroptosis through the STAT3/P53/SLC7A11 Axis in Osteosarcoma Cells

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yi Luo ◽  
Xu Gao ◽  
Luetao Zou ◽  
Miao Lei ◽  
Junming Feng ◽  
...  
Keyword(s):  
Cell Death ◽  
Glutathione Depletion ◽  
Ros Generation ◽  
Mitochondrial Morphology ◽  
Iron Level ◽  
Intracellular Iron ◽  
Divalent Metal Transporter 1 ◽  
Divalent Metal Transporter ◽  
Metal Transporter ◽  
Regulated Cell Death

Ferroptosis is a new form of regulated cell death, which is mediated by intracellular iron. Although it is reported that bavachin has antitumour effects on several tumour cells and prompts the reactive oxygen species (ROS) generation, it is unclear whether ferroptosis can be induced by bavachin in osteosarcoma (OS) cells. In this study, we found that bavachin inhibits the viability of MG63 and HOS OS cell lines along with an increase in the ferrous iron level, ROS accumulation, malondialdehyde overexpression, and glutathione depletion. Moreover, iron chelators (deferoxamine), antioxidants (Vit E), and ferroptosis inhibitors (ferrostatin-1 and liproxstatin-1) reverse bavachin-induced cell death. Bavachin also altered the mitochondrial morphology of OS cells, leading to smaller mitochondria, higher density of the mitochondrial membrane, and reduced mitochondrial cristae. Further investigation showed that bavachin upregulated the expression of transferrin receptor, divalent metal transporter-1, and P53, along with downregulating the expression of ferritin light chain, ferritin heavy chain, p-STAT3 (705), SLC7A11, and glutathione peroxidase-4 in OS cells. More importantly, STAT3 overexpression, SLC7A11 overexpression, and pretreatment with pifithrin-α (P53 inhibitor) rescued OS cell ferroptosis induced by bavachin. The results show that bavachin induces ferroptosis via the STAT3/P53/SLC7A11 axis in OS cells.

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