scholarly journals Ubiquitin-Like Modifiers: Emerging Regulators of Protozoan Parasites

Biomolecules ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1403
Author(s):  
Maryia Karpiyevich ◽  
Katerina Artavanis-Tsakonas
Keyword(s):  
Mammalian Cells ◽  
Dynamic Balance ◽  
Fine Tuning ◽  
Protozoan Parasites ◽  
Cellular Functions ◽  
Parasitic Protozoa ◽  
Distinctive Features ◽  
Cellular Processes ◽  
Wide Range ◽  
Enzymatic Machinery

Post-translational protein regulation allows for fine-tuning of cellular functions and involves a wide range of modifications, including ubiquitin and ubiquitin-like modifiers (Ubls). The dynamic balance of Ubl conjugation and removal shapes the fates of target substrates, in turn modulating various cellular processes. The mechanistic aspects of Ubl pathways and their biological roles have been largely established in yeast, plants, and mammalian cells. However, these modifiers may be utilised differently in highly specialised and divergent organisms, such as parasitic protozoa. In this review, we explore how these parasites employ Ubls, in particular SUMO, NEDD8, ATG8, ATG12, URM1, and UFM1, to regulate their unconventional cellular physiology. We discuss emerging data that provide evidence of Ubl-mediated regulation of unique parasite-specific processes, as well as the distinctive features of Ubl pathways in parasitic protozoa. We also highlight the potential to leverage these essential regulators and their cognate enzymatic machinery for development of therapeutics to protect against the diseases caused by protozoan parasites.

scholarly journals The AAA+ ATPase p97, a cellular multitool

2017 ◽  
Vol 474 (17) ◽  
pp. 2953-2976 ◽  
Author(s):  
Lasse Stach ◽  
Paul S. Freemont
Keyword(s):  
Atp Hydrolysis ◽  
Current Status ◽  
Cellular Functions ◽  
Aaa Atpase ◽  
Cellular Processes ◽  
Proteotoxic Stress ◽  
Binding Domains ◽  
Wide Range ◽  
Aaa Atpases ◽  
Substrate Proteins

The AAA+ (ATPases associated with diverse cellular activities) ATPase p97 is essential to a wide range of cellular functions, including endoplasmic reticulum-associated degradation, membrane fusion, NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation and chromatin-associated processes, which are regulated by ubiquitination. p97 acts downstream from ubiquitin signaling events and utilizes the energy from ATP hydrolysis to extract its substrate proteins from cellular structures or multiprotein complexes. A multitude of p97 cofactors have evolved which are essential to p97 function. Ubiquitin-interacting domains and p97-binding domains combine to form bi-functional cofactors, whose complexes with p97 enable the enzyme to interact with a wide range of ubiquitinated substrates. A set of mutations in p97 have been shown to cause the multisystem proteinopathy inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia. In addition, p97 inhibition has been identified as a promising approach to provoke proteotoxic stress in tumors. In this review, we will describe the cellular processes governed by p97, how the cofactors interact with both p97 and its ubiquitinated substrates, p97 enzymology and the current status in developing p97 inhibitors for cancer therapy.

scholarly journals Regulation of circular dorsal ruffles, macropinocytosis, and cell migration by RhoG and its exchange factor, Trio

2017 ◽  
Vol 28 (13) ◽  
pp. 1768-1781 ◽  
Author(s):  
Alejandra Valdivia ◽  
Silvia M. Goicoechea ◽  
Sahezeel Awadia ◽  
Ashtyn Zinn ◽  
Rafael Garcia-Mata
Keyword(s):  
Cell Migration ◽  
Mammalian Cells ◽  
Dorsal Surface ◽  
Receptor Internalization ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Unique Type ◽  
Exchange Factor ◽  
Cellular Processes

Circular dorsal ruffles (CDRs) are actin-rich structures that form on the dorsal surface of many mammalian cells in response to growth factor stimulation. CDRs represent a unique type of structure that forms transiently and only once upon stimulation. The formation of CDRs involves a drastic rearrangement of the cytoskeleton, which is regulated by the Rho family of GTPases. So far, only Rac1 has been consistently associated with CDR formation, whereas the role of other GTPases in this process is either lacking or inconclusive. Here we show that RhoG and its exchange factor, Trio, play a role in the regulation of CDR dynamics, particularly by modulating their size. RhoG is activated by Trio downstream of PDGF in a PI3K- and Src-dependent manner. Silencing RhoG expression decreases the number of cells that form CDRs, as well as the area of the CDRs. The regulation of CDR area by RhoG is independent of Rac1 function. In addition, our results show the RhoG plays a role in the cellular functions associated with CDR formation, including macropinocytosis, receptor internalization, and cell migration. Taken together, our results reveal a novel role for RhoG in the regulation of CDRs and the cellular processes associated with their formation.

scholarly journals A Novel Domain within the DEAD-Box Protein DP103 Is Essential for Transcriptional Repression and Helicase Activity

2003 ◽  
Vol 23 (1) ◽  
pp. 414-423 ◽  
Author(s):  
Xiaomei Yan ◽  
Jean-François Mouillet ◽  
Qinglin Ou ◽  
Yoel Sadovsky
Keyword(s):  
Transcriptional Repression ◽  
Mammalian Cells ◽  
Posttranslational Regulation ◽  
Helicase Activity ◽  
Cellular Functions ◽  
Terminal Domain ◽  
Dead Box ◽  
Wide Range ◽  
The Dead ◽  
Necessary And Sufficient

ABSTRACT Members of the DEAD-box family of helicases, distinguished by a core characteristic sequence of Asp-Glu-Ala-Asp, are expressed in a wide range of prokaryotes and eukaryotes and exhibit diverse cellular functions, including DNA transcription, recombination and repair, RNA processing, translation, and posttranslational regulation. Although ubiquitous, the function of most DEAD-box proteins is unknown. We and others have recently cloned DP103, which harbors conserved DEAD-box, helicase, and ATPase domains in its N terminus. DP103 (also termed Gemin3 and DDX20) interacts with SF-1, SMN, EBNA2, and EBNA3C in mammalian cells. Here we demonstrate that a discrete domain within the nonconserved C-terminal region of DP103 directly interacts with SF-1. This domain exhibits an autonomous repression function and is necessary and sufficient for repressing the transcriptional activity of SF-1. Furthermore, intact DP103 exhibits helicase activity. Importantly, the C-terminal domain is obligatory but not sufficient for this unwinding activity of DP103. Together, our results support a novel paradigm for transcriptional repression and demonstrate the bifunctional role of the C-terminal domain of DP103.

Cellular consequences of inositol depletion

2009 ◽  
Vol 37 (5) ◽  
pp. 1099-1103 ◽  
Author(s):  
Rania M. Deranieh ◽  
Miriam L. Greenberg
Keyword(s):  
Bipolar Disorder ◽  
Inositol Phosphates ◽  
Signalling Pathway ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Wide Range ◽  
Therapeutic Mechanism

The inositol-depletion hypothesis was suggested to explain the therapeutic mechanism of mood-stabilizing drugs. Focus was previously on the phosphatidylinositol signalling pathway and on the regulatory roles of Ins(3,4,5)P3 and DAG (diacylglycerol). Recent findings indicate that inositol and inositol-containing molecules, including phosphoinositides and inositol phosphates, have signalling and regulatory roles in many cellular processes. This suggests that depleting inositol may lead to perturbation of a wide range of cellular functions, at least some of which may be associated with bipolar disorder.

scholarly journals Hints From the Cellular Functions to the Practical Outlook of Circular RNAs

2021 ◽  
Vol 12 ◽  
Author(s):  
Liora Yesharim ◽  
Marzieh Mojbafan ◽  
Maryam Abiri
Keyword(s):  
Immune System ◽  
Mammalian Cells ◽  
Circular Rnas ◽  
Human Beings ◽  
Practical Application ◽  
Cellular Functions ◽  
Functional Roles ◽  
Cellular Processes ◽  
History Of ◽  
The Origin Of Life

Although it has been about 30 years since the discovery of circular RNAs (circRNAs) in mammalian cells, these subtypes of RNAs’ capabilities have come into focus in recent years. The unique structure and various functional roles of circRNAs in many cellular processes have aroused researchers’ interest and raised many questions about whether circRNAs can facilitate the diagnosis and treatment of diseases. To answer these questions, we will illustrate the main known functions and regulatory roles of circRNAs in the cell after presenting a brief history of the discovery of circRNAs and the main proposed theories of the biogenesis of circRNAs. Afterward, the practical application of circRNAs as biomarkers of different pathophysiological conditions will be discussed, mentioning some examples and challenges in this area. We also consider one of the main questions that human beings have always been faced, “the origin of life,” and its possible connection to circRNAs. Finally, focusing on the various capabilities of circRNAs, we discuss their potential therapeutic applications considering the immunity response toward exogenous circRNAs. However, there are still disputes about the exact immune system reaction, which we will discuss in detail.

scholarly journals Dronc-independent basal executioner caspase activity sustains Drosophila imaginal tissue growth

2019 ◽  
Vol 116 (41) ◽  
pp. 20539-20544 ◽  
Author(s):  
Natsuki Shinoda ◽  
Nozomi Hanawa ◽  
Takahiro Chihara ◽  
Akiko Koto ◽  
Masayuki Miura
Keyword(s):  
Cell Death ◽  
Tissue Growth ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Spatiotemporal Regulation ◽  
C Terminus ◽  
Wide Range ◽  
Executioner Caspases ◽  
Proteolytic Cleavages ◽  
Wing Growth

Caspase is best known as an enzyme involved in programmed cell death, which is conserved among multicellular organisms. In addition to its role in cell death, caspase is emerging as an indispensable enzyme in a wide range of cellular functions, which have recently been termed caspase-dependent nonlethal cellular processes (CDPs). In this study, we examined the involvement of cell death signaling in tissue-size determination using Drosophila wing as a model. We found that the Drosophila executioner caspases Dcp-1 and Decay, but not Drice, promoted wing growth independently of apoptosis. Most of the reports on CDPs argue the importance of the spatiotemporal regulation of the initiator caspase, Dronc; however, this sublethal caspase function was independent of Dronc, suggesting a more diverse array of CDP regulatory mechanisms. Tagging of TurboID, an improved promiscuous biotin ligase that biotinylates neighboring proteins, to the C terminus of caspases revealed the differences among the neighbors of executioner caspases. Furthermore, we found that the cleavage of Acinus, a substrate of the executioner caspase, was important in promoting wing growth. These results demonstrate the importance of executioner caspase-mediated basal proteolytic cleavage of substrates in sustaining tissue growth. Given the existence of caspase-like DEVDase activity in a unicellular alga, our results likely highlight the original function of caspase—not cell death, but basal proteolytic cleavages for cell vigor.

scholarly journals MicroRNA-Mediated Health-Promoting Effects of Phytochemicals

2019 ◽  
Vol 20 (10) ◽  
pp. 2535 ◽  
Author(s):  
Hara Kang
Keyword(s):  
Human Health ◽  
Molecular Mechanisms ◽  
Fine Tuning ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Target Mrnas ◽  
Therapeutic Benefits ◽  
Health Promoting ◽  
Apoptosis And Inflammation ◽  
Potential Use

Phytochemicals are known to benefit human health by modulating various cellular processes, including cell proliferation, apoptosis, and inflammation. Due to the potential use of phytochemicals as therapeutic agents against human diseases such as cancer, studies are ongoing to elucidate the molecular mechanisms by which phytochemicals affect cellular functions. It has recently been shown that phytochemicals may regulate the expression of microRNAs (miRNAs). MiRNAs are responsible for the fine-tuning of gene expression by controlling the expression of their target mRNAs in both normal and pathological cells. This review summarizes the recent findings regarding phytochemicals that modulate miRNA expression and promote human health by exerting anticancer, photoprotective, and anti-hepatosteatosis effects. Identifying miRNAs modulated by phytochemicals and understanding the regulatory mechanisms mediated by their target mRNAs will facilitate the efforts to maximize the therapeutic benefits of phytochemicals.

scholarly journals Autophagic degradation of peroxisomes in mammals

2016 ◽  
Vol 44 (2) ◽  
pp. 431-440 ◽  
Author(s):  
Katarzyna Zientara-Rytter ◽  
Suresh Subramani
Keyword(s):  
Mammalian Cells ◽  
Environmental Changes ◽  
Cell Function ◽  
Current Knowledge ◽  
Future Directions ◽  
Cellular Processes ◽  
Wide Range ◽  
Efficient Control ◽  
Autophagic Degradation ◽  
Eukaryotic Organisms

Peroxisomes are essential organelles required for proper cell function in all eukaryotic organisms. They participate in a wide range of cellular processes including the metabolism of lipids and generation, as well as detoxification, of hydrogen peroxide (H2O2). Therefore, peroxisome homoeostasis, manifested by the precise and efficient control of peroxisome number and functionality, must be tightly regulated in response to environmental changes. Due to the existence of many physiological disorders and diseases associated with peroxisome homoeostasis imbalance, the dynamics of peroxisomes have been widely examined. The increasing volume of reports demonstrating significant involvement of the autophagy machinery in peroxisome removal leads us to summarize current knowledge of peroxisome degradation in mammalian cells. In this review we present current models of peroxisome degradation. We particularly focus on pexophagy–the selective clearance of peroxisomes through autophagy. We also critically discuss concepts of peroxisome recognition for pexophagy, including signalling and selectivity factors. Finally, we present examples of the pathological effects of pexophagy dysfunction and suggest promising future directions.

scholarly journals Ultrasound Imaging of Gene Expression in Mammalian Cells

2019 ◽  
Author(s):  
Arash Farhadi ◽  
Gabrielle H. Ho ◽  
Daniel P. Sawyer ◽  
Raymond W. Bourdeau ◽  
Mikhail G. Shapiro
Keyword(s):  
Gene Expression ◽  
Mammalian Cells ◽  
Reporter Genes ◽  
Tissue Imaging ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Deep Tissue Imaging ◽  
And Function ◽  
Expression In Mammalian Cells

ABSTRACTThe study of cellular processes occurring inside intact organisms and the development of cell-based diagnostic and therapeutic agents requires methods to visualize cellular functions such as gene expression in deep tissues. Ultrasound is a widely used biomedical technology enabling deep-tissue imaging with high spatial and temporal resolution. However, no genetically encoded molecular reporters are available to connect ultrasound contrast to gene expression in mammalian cells. To address this limitation, we introduce the first mammalian acoustic reporter genes. Starting with an eleven-gene polycistronic gene cluster derived from bacteria, we engineered a eukaryotic genetic program whose introduction into mammalian cells results in the expression of a unique class of intracellular air-filled protein nanostructures called gas vesicles. The scattering of ultrasound by these nanostructures allows mammalian cells to be visualized at volumetric densities below 0.5%, enables the monitoring of dynamic circuit-driven gene expression, and permits high-resolution imaging of gene expression in living animals. These mammalian acoustic reporter genes enable previously impossible approaches to monitoring the location, viability and function of mammalian cellsin vivo.

scholarly journals Ultrasound imaging of gene expression in mammalian cells

Science ◽  
2019 ◽  
Vol 365 (6460) ◽  
pp. 1469-1475 ◽  
Author(s):  
Arash Farhadi ◽  
Gabrielle H. Ho ◽  
Daniel P. Sawyer ◽  
Raymond W. Bourdeau ◽  
Mikhail G. Shapiro
Keyword(s):  
Gene Expression ◽  
Mammalian Cells ◽  
Reporter Genes ◽  
High Resolution Imaging ◽  
Gas Vesicles ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Ultrasound Contrast ◽  
Resolution Imaging ◽  
Expression In Mammalian Cells

The study of cellular processes occurring inside intact organisms requires methods to visualize cellular functions such as gene expression in deep tissues. Ultrasound is a widely used biomedical technology enabling noninvasive imaging with high spatial and temporal resolution. However, no genetically encoded molecular reporters are available to connect ultrasound contrast to gene expression in mammalian cells. To address this limitation, we introduce mammalian acoustic reporter genes. Starting with a gene cluster derived from bacteria, we engineered a eukaryotic genetic program whose introduction into mammalian cells results in the expression of intracellular air-filled protein nanostructures called gas vesicles, which produce ultrasound contrast. Mammalian acoustic reporter genes allow cells to be visualized at volumetric densities below 0.5% and permit high-resolution imaging of gene expression in living animals.

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