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 Regulation of peroxisomal trafficking and distribution

2020 ◽  
Author(s):  
Christian Covill-Cooke ◽  
Viktoriya S. Toncheva ◽  
Josef T. Kittler
Keyword(s):  
Rho Gtpases ◽  
Mammalian Cells ◽  
Short Range ◽  
Current Knowledge ◽  
Current Understanding ◽  
Regulatory Mechanisms ◽  
Future Directions ◽  
Contact Sites ◽  
Wide Range

Abstract Peroxisomes are organelles that perform a wide range of essential metabolic processes. To ensure that peroxisomes are optimally positioned in the cell, they must be transported by both long- and short-range trafficking events in response to cellular needs. Here, we review our current understanding of the mechanisms by which the cytoskeleton and organelle contact sites alter peroxisomal distribution. Though the focus of the review is peroxisomal transport in mammalian cells, findings from flies and fungi are used for comparison and to inform the gaps in our understanding. Attention is given to the apparent overlap in regulatory mechanisms for mitochondrial and peroxisomal trafficking, along with the recently discovered role of the mitochondrial Rho-GTPases, Miro, in peroxisomal dynamics. Moreover, we outline and discuss the known pathological and pharmacological conditions that perturb peroxisomal positioning. We conclude by highlighting several gaps in our current knowledge and suggest future directions that require attention.

scholarly journals MicroRNAs: crucial regulators of placental development

Reproduction ◽  
2018 ◽  
Vol 155 (6) ◽  
pp. R259-R271 ◽  
Author(s):  
Heyam Hayder ◽  
Jacob O’Brien ◽  
Uzma Nadeem ◽  
Chun Peng
Keyword(s):  
Mrna Stability ◽  
Target Genes ◽  
Current Knowledge ◽  
Mirna Biogenesis ◽  
Placental Development ◽  
Future Directions ◽  
Cellular Processes ◽  
Wide Range ◽  
Canonical Pathways

MicroRNAs (miRNAs) are small non-coding single-stranded RNAs that are integral to a wide range of cellular processes mainly through the regulation of translation and mRNA stability of their target genes. The placenta is a transient organ that exists throughout gestation in mammals, facilitating nutrient and gas exchange and waste removal between the mother and the fetus. miRNAs are expressed in the placenta, and many studies have shown that miRNAs play an important role in regulating trophoblast differentiation, migration, invasion, proliferation, apoptosis, vasculogenesis/angiogenesis and cellular metabolism. In this review, we provide a brief overview of canonical and non-canonical pathways of miRNA biogenesis and mechanisms of miRNA actions. We highlight the current knowledge of the role of miRNAs in placental development. Finally, we point out several limitations of the current research and suggest future directions.

scholarly journals RNA G-Quadruplex Structures Mediate Gene Regulation in Bacteria

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaolong Shao ◽  
Weitong Zhang ◽  
Mubarak Ishaq Umar ◽  
Hei Yuen Wong ◽  
Zijing Seng ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Cell Envelope ◽  
Bacterial Species ◽  
Virulence Gene ◽  
Content Type ◽  
Cellular Processes ◽  
Wide Range ◽  
G Quadruplex ◽  
Eukaryotic Organisms

ABSTRACT Guanine (G)-rich sequences in RNA can fold into diverse RNA G-quadruplex (rG4) structures to mediate various biological functions and cellular processes in eukaryotic organisms. However, the presence, locations, and functions of rG4s in prokaryotes are still elusive. We used QUMA-1, an rG4-specific fluorescent probe, to detect rG4 structures in a wide range of bacterial species both in vitro and in live cells and found rG4 to be an abundant RNA secondary structure across those species. Subsequently, to identify bacterial rG4 sites in the transcriptome, the model Escherichia coli strain and a major human pathogen, Pseudomonas aeruginosa, were subjected to recently developed high-throughput rG4 structure sequencing (rG4-seq). In total, 168 and 161 in vitro rG4 sites were found in E. coli and P. aeruginosa, respectively. Genes carrying these rG4 sites were found to be involved in virulence, gene regulation, cell envelope synthesis, and metabolism. More importantly, biophysical assays revealed the formation of a group of rG4 sites in mRNAs (such as hemL and bswR), and they were functionally validated in cells by genetic (point mutation and lux reporter assays) and phenotypic experiments, providing substantial evidence for the formation and function of rG4s in bacteria. Overall, our study uncovers important regulatory functions of rG4s in bacterial pathogenicity and metabolic pathways and strongly suggests that rG4s exist and can be detected in a wide range of bacterial species. IMPORTANCE G-quadruplex in RNA (rG4) mediates various biological functions and cellular processes in eukaryotic organisms. However, the presence, locations, and functions of rG4 are still elusive in prokaryotes. Here, we found that rG4 is an abundant RNA secondary structure across a wide range of bacterial species. Subsequently, the transcriptome-wide rG4 structure sequencing (rG4-seq) revealed that the model E. coli strain and a major human pathogen, P. aeruginosa, have 168 and 161 in vitro rG4 sites, respectively, involved in virulence, gene regulation, cell envelope, and metabolism. We further verified the regulatory functions of two rG4 sites in bacteria (hemL and bswR). Overall, this finding strongly suggests that rG4s play key regulatory roles in a wide range of bacterial species.

scholarly journals Unconventional Myosins: How Regulation Meets Function

2019 ◽  
Vol 21 (1) ◽  
pp. 67 ◽  
Author(s):  
Natalia Fili ◽  
Christopher P. Toseland
Keyword(s):  
Molecular Motors ◽  
Current Knowledge ◽  
Local Environment ◽  
Structural Features ◽  
Regulatory Mechanisms ◽  
Tight Control ◽  
Cellular Processes ◽  
Binding Partners ◽  
Wide Range ◽  
Multiple Levels

Unconventional myosins are multi-potent molecular motors that are assigned important roles in fundamental cellular processes. Depending on their mechano-enzymatic properties and structural features, myosins fulfil their roles by acting as cargo transporters along the actin cytoskeleton, molecular anchors or tension sensors. In order to perform such a wide range of roles and modes of action, myosins need to be under tight regulation in time and space. This is achieved at multiple levels through diverse regulatory mechanisms: the alternative splicing of various isoforms, the interaction with their binding partners, their phosphorylation, their applied load and the composition of their local environment, such as ions and lipids. This review summarizes our current knowledge of how unconventional myosins are regulated, how these regulatory mechanisms can adapt to the specific features of a myosin and how they can converge with each other in order to ensure the required tight control of their function.

Epigenetic regulation of geminivirus pathogenesis: a case of relentless recalibration of defence responses in plants

2020 ◽  
Vol 71 (22) ◽  
pp. 6890-6906 ◽  
Author(s):  
Fauzia Zarreen ◽  
Supriya Chakraborty
Keyword(s):  
Viral Genome ◽  
Current Knowledge ◽  
Plant Viruses ◽  
Limited Evidence ◽  
Host Proteins ◽  
Crop Species ◽  
Cellular Processes ◽  
Wide Range ◽  
Defence Responses ◽  
Epigenetic Processes

Abstract Geminiviruses constitute one of the largest families of plant viruses and they infect many economically important crops. The proteins encoded by the single-stranded DNA genome of these viruses interact with a wide range of host proteins to cause global dysregulation of cellular processes and help establish infection in the host. Geminiviruses have evolved numerous mechanisms to exploit host epigenetic processes to ensure the replication and survival of the viral genome. Here, we review our current knowledge of diverse epigenetic processes that have been implicated in the regulation of geminivirus pathogenesis, including DNA methylation, histone post-transcriptional modification, chromatin remodelling, and nucleosome repositioning. In addition, we discuss the currently limited evidence of host epigenetic defence responses that are aimed at counteracting geminivirus infection, and the potential for exploiting these responses for the generation of resistance against geminiviruses in crop species.

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.

Creating a customized intracellular niche: subversion of host cell signaling byLegionellatype IV secretion system effectors

2015 ◽  
Vol 61 (9) ◽  
pp. 617-635 ◽  
Author(s):  
Ernest C. So ◽  
Corinna Mattheis ◽  
Edward W. Tate ◽  
Gad Frankel ◽  
Gunnar N. Schroeder
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Current Knowledge ◽  
Secretion System ◽  
Effector Proteins ◽  
Cellular Processes ◽  
Type Iv ◽  
Open Questions ◽  
Exact Function ◽  
Wide Range

The Gram-negative facultative intracellular pathogen Legionella pneumophila infects a wide range of different protozoa in the environment and also human alveolar macrophages upon inhalation of contaminated aerosols. Inside its hosts, it creates a defined and unique compartment, termed the Legionella-containing vacuole (LCV), for survival and replication. To establish the LCV, L. pneumophila uses its Dot/Icm type IV secretion system (T4SS) to translocate more than 300 effector proteins into the host cell. Although it has become apparent in the past years that these effectors subvert a multitude of cellular processes and allow Legionella to take control of host cell vesicle trafficking, transcription, and translation, the exact function of the vast majority of effectors still remains unknown. This is partly due to high functional redundancy among the effectors, which renders conventional genetic approaches to elucidate their role ineffective. Here, we review the current knowledge about Legionella T4SS effectors, highlight open questions, and discuss new methods that promise to facilitate the characterization of T4SS effector functions in the future.

scholarly journals The RhoGEF Trio: A Protein with a Wide Range of Functions in the Vascular Endothelium

2021 ◽  
Vol 22 (18) ◽  
pp. 10168
Author(s):  
Lanette Kempers ◽  
Amber J. M. Driessen ◽  
Jos van Rijssel ◽  
Martijn A. Nolte ◽  
Jaap D. van Buul
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Function ◽  
Small Gtpases ◽  
Nucleotide Exchange ◽  
Endothelial Cell Function ◽  
Cellular Processes ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Wide Range ◽  
Range Of Functions

Many cellular processes are controlled by small GTPases, which can be activated by guanine nucleotide exchange factors (GEFs). The RhoGEF Trio contains two GEF domains that differentially activate the small GTPases such as Rac1/RhoG and RhoA. These small RhoGTPases are mainly involved in the remodeling of the actin cytoskeleton. In the endothelium, they regulate junctional stabilization and play a crucial role in angiogenesis and endothelial barrier integrity. Multiple extracellular signals originating from different vascular processes can influence the activity of Trio and thereby the regulation of the forementioned small GTPases and actin cytoskeleton. This review elucidates how various signals regulate Trio in a distinct manner, resulting in different functional outcomes that are crucial for endothelial cell function in response to inflammation.

scholarly journals Children’s Independent Mobility: Current Knowledge, Future Directions, and Public Health Implications

2018 ◽  
Vol 15 (11) ◽  
pp. 2441 ◽  
Author(s):  
Isabel Marzi ◽  
Anne Reimers
Keyword(s):  
Public Health ◽  
Traffic Safety ◽  
Motor Development ◽  
Environmental Changes ◽  
Current Knowledge ◽  
Relevant Literature ◽  
Environmental Benefits ◽  
Independent Mobility ◽  
Public Health Perspective ◽  
Future Directions

Environmental changes significantly impact health behavior. Active travel behavior is mostly affected by increasing motorization, urban sprawl, and traffic safety. Especially for children, active and independent travel can contribute to physical activity, social and motor development, and other health-related outcomes. A reduced number of children engaging in independent mobility over the last 20 years demanded researchers to further examine the construct of children’s independent mobility. By examining relevant literature, this narrative review aims to provide the current state of knowledge on children’s independent mobility, and identify future directions in research, as well as practical implications. From a public health perspective, considering children’s independent mobility in intervention programs is recommended, since it is associated with numerous health and environmental benefits. To develop interventions, multilevel socio-ecological influences on children’s independent mobility are widely examined; however, evidence is limited due to heterogeneous measurements and a lack of high-quality prospective studies. To oppose the decline in children’s independent mobility, further analysis using comparable measures is needed to understand the determinants of children’s independent mobility and to enable international comparison.

scholarly journals Mitochondrial division, fusion and degradation

2019 ◽  
Vol 167 (3) ◽  
pp. 233-241 ◽  
Author(s):  
Daisuke Murata ◽  
Kenta Arai ◽  
Miho Iijima ◽  
Hiromi Sesaki
Keyword(s):  
Super Resolution ◽  
Healthy Population ◽  
Lipid Biochemistry ◽  
Mitochondrial Division ◽  
Cellular Processes ◽  
Size Number ◽  
Wide Range ◽  
Autophagic Degradation ◽  
And Function

Abstract The mitochondrion is an essential organelle for a wide range of cellular processes, including energy production, metabolism, signal transduction and cell death. To execute these functions, mitochondria regulate their size, number, morphology and distribution in cells via mitochondrial division and fusion. In addition, mitochondrial division and fusion control the autophagic degradation of dysfunctional mitochondria to maintain a healthy population. Defects in these dynamic membrane processes are linked to many human diseases that include metabolic syndrome, myopathy and neurodegenerative disorders. In the last several years, our fundamental understanding of mitochondrial fusion, division and degradation has been significantly advanced by high resolution structural analyses, protein-lipid biochemistry, super resolution microscopy and in vivo analyses using animal models. Here, we summarize and discuss this exciting recent progress in the mechanism and function of mitochondrial division and fusion.

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