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Topic Review
Biography
Topic Review
Growth and Division of Peroxisomes
The identification and molecular characterization of peroxisomal division proteins, microscopic observations and the analysis of patient fibroblasts have contributed to a refined growth and division model for peroxisomes. In mammalian cells, peroxisome formation by membrane growth and division represents a multi-step process involving the remodelling of the peroxisomal membrane, membrane expansion/elongation (growth), membrane constriction and final scission (fission). Peroxisomal growth and division results in the formation of new peroxisomes (multiplication/proliferation), which import matrix and membrane proteins to maintain functionality.
294
23 Jun 2022
Topic Review
GRKs
G protein-coupled receptor (GPCR) kinases (GRKs) play an important role in the regulation of signaling of GPCRs that bind neurotransmitters. The canonical model of GPCR desensitization posits that GRKs phosphorylate ligand-activated GPCRs, and this phosphorylation prepares receptors for the high-affinity binding of arrestin proteins. Arrestin binding prevents further G protein coupling, promotes receptor internalization, and initiates and/or facilitates specific branches of signaling. Existing data suggest that the role of GPCR phosphorylation by GRKs is distinct in different receptors. The relationship between G protein- and arrestin-mediated signaling on the one hand, and therapeutic and side effects of drugs on the other, is more complex than is widely believed. Also, the relationship between rapid (minutes to hours) GRK/arrestin-mediated regulation and long-term (days to weeks) neural plasticity remains to be elucidated.
1.2K
19 Jan 2021
Topic Review
Graviperception and Graviresponses in
Euglena gracilis
The genus Euglena contains unicellular eukaryotic flagellates. In addition to light and chemicals, the cells perceive the gravitational field of the Earth and orient themselves paralell to the gravivector to optimize their position in the water column. The perception is based on transient receptor proteins in the membrane which are stimulated by the pressure of the cell content onto the lower membrane. Upon stimulation these proteins open and allow the influx of calcium from the outer medium which binds to a specific calmodulin. In turn this enzyme activates a adenylyl cyclase which produces cAMP believed to stimulate a phosphodiesterase A which finally modifies a flagellar protein which results in a course correction. Since Euglena is photosynthetic it absorbs carbon dioxide and produces oxygen and is thus an excellent candidate for a bioregenerative life support system during long-term space flights.
459
04 Nov 2022
Topic Review
Gq Signaling in Autophagy Control
All processes in human physiology relies on homeostatic mechanisms which require the activation of specific control circuits to adapt the changes imposed by external stimuli. One of the critical modulators of homeostatic balance is autophagy, a catabolic process that is responsible of the destruction of long-lived proteins and organelles through a lysosome degradative pathway. Identification of the mechanism underlying autophagic flux is considered of great importance as both protective and detrimental functions are linked with deregulated autophagy. At the mechanistic and regulatory levels, autophagy is activated in response to diverse stress conditions (food deprivation, hyperthermia and hypoxia), even a novel perspective highlight the potential role of physical forces in autophagy modulation. To understand the crosstalk between all these controlling mechanisms could give people new clues about the specific contribution of autophagy in a wide range of diseases including vascular disorders, inflammation and cancer.
411
02 Sep 2022
Topic Review
GPR15 in Vascular Tissue
GPR15 as a member of the Class A (rhodopsin) orphan G protein-coupled receptor (GPCR) family has been recently deorphanized by identification of two endogenous receptor-activating ligands in human. Interestingly, in vascular tissue they interact apparently with different cell types. While one ligand triggers a cytoprotective effect on endothelial cells from the luminal site of vessels, the other ligand is rather responsible for the homing of GPR15-expressing lymphocytes into the colon. Thus, in addition to the role of GPR15 as a co-receptor for the human immunodeficiency virus (HIV) or to the expansion of GPR15-expressing lymphocytes in blood by chronic smoking this review will summarize findings to the role of GPR15 for vascular tissue based on new described receptor-ligand interactions.
452
21 Oct 2021
Topic Review
GPCRs In Intracellular Compartments: Implications For Drug Discovery
The architecture of eukaryotic cells is defined by extensive membrane-delimited compartments, which entails separate metabolic processes that would otherwise interfere with each other, leading to functional differences between cells. G protein-coupled receptors (GPCRs) are the largest class of cell surface receptors, and their signal transduction is traditionally viewed as a chain of events initiated from the plasma membrane. Furthermore, their intracellular trafficking, internalization, and recycling were considered only to regulate receptor desensitization and cell surface expression. On the contrary, accumulating data strongly suggest that GPCRs also signal from intracellular compartments. GPCRs localize in the membranes of endosomes, nucleus, Golgi and endoplasmic reticulum apparatuses, mitochondria, and cell division compartments. Importantly, from these sites they have shown to orchestrate multiple signals that regulate different cell pathways.
545
08 Oct 2022
Topic Review
GPCR, ER Stress, and EMT
Endoplasmic reticular stress (ERS) is a dynamics adaptive mechanism that is triggered upon perturbations in ER homeostasis. Hence unfolded protein response (UPR) is activated by ERS as a distress signal. UPR is involved in cancer progression by aiding cells to adapt harsh environments and evading cell death. We have made a significant discovery in the area of ERS and cell death in colonic epithelial cells where have previously unraveled the relationship between ERS and anti- apoptotic protein Survivin in colon cancer cells. We established a time point for an aggressive ERS environment with the help of ERS dynamics thereby creating a perfect environment for testing drugs. However, the role of ERS in cancer is still perplexing. G-protein coupled receptors (GCPR) are another large family of cell surface receptors that respond to a variety of external signals. GPCRs are said to have an active association with ERS in order to trigger some key processes like epithelial mesenchymal transition (EMT) which is a prime step in metastasis. However, there are some essential candidates that play a role in hindering cancer progression through numerous pathways. We therefore wish to provide the readers with an exhaustive views and insights of ER stress biology.
1.0K
12 Oct 2020
Topic Review
Golgi Proteostasis
The Golgi apparatus is a central hub for cellular protein trafficking and signaling. Golgi structure and function is tightly coupled and undergoes dynamic changes in health and disease. A crucial requirement for maintaining Golgi homeostasis is the ability of the Golgi to target aberrant, misfolded, or otherwise unwanted proteins to degradation. Recent studies have revealed that the Golgi apparatus may degrade such proteins through autophagy, retrograde trafficking to the ER for ER-associated degradation (ERAD), and locally, through Golgi apparatus-related degradation (GARD).
477
02 Mar 2022
Topic Review
Golgi Metal Ion Homeostasis (Ca2+/Mn2+)
The Golgi apparatus is an organelle found in most eukaryotic cells. Being part of the endomembrane system in the cytoplasm, it resides at the intersection of the exocytic and endocytic pathways, and works mainly in post-translational modifications and sorting of lipids and proteins. One unique characteristic of the Golgi is the multilayer stack that divides the Golgi membrane system into several sub-compartments known as cis-, medial, and trans-Golgi, each of which contains a set of glycosylation enzymes that sequentially remove or add various sugar monomers to proteins as they pass through the Golgi. To fulfill its function, the Golgi structure is highly dynamic, while Golgi structure and function are tightly regulated. Similarly, the microenvironment of each sub-compartment is also under strict regulation in response to intracellular environmental changes.
344
19 Jan 2022
Topic Review
Glycosylation of Cancer Extracellular Vesicles
Glycans are major constituents of extracellular vesicles (EVs). Alterations in the glycosylation pathway are a common feature of cancer cells, which gives rise to de novo or increased synthesis of particular glycans. Therefore, glycans and glycoproteins have been widely used in the clinic as both stratification and prognosis cancer biomarkers. Interestingly, several of the tumor-associated glycans have already been identified in cancer EVs, which constitutes valuable sources of cancer biomarkers. Furthermore, glycans have also shown to play a role in EV protein sorting, uptake and tropism. Altogether, the EV glycan signatures hold tremendous potential to be applied into the clinical setting for both biomarker discovery and as therapeutic delivery systems.
1.1K
25 Jan 2021
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