scholarly journals Progress and perspectives in signal transduction, actin dynamics, and movement at the cell and tissue level: lessons from Dictyostelium

2016 ◽  
Vol 6 (5) ◽  
pp. 20160047 ◽  
Author(s):  
Till Bretschneider ◽  
Hans G. Othmer ◽  
Cornelis J. Weijer
Keyword(s):  
Signal Transduction ◽  
Wound Repair ◽  
Membrane Receptors ◽  
Force Generation ◽  
Actin Dynamics ◽  
Bacterial Invasion ◽  
Directed Motion ◽  
Directed Movement ◽  
Produce Cell ◽  
Intracellular Signals

Movement of cells and tissues is a basic biological process that is used in development, wound repair, the immune response to bacterial invasion, tumour formation and metastasis, and the search for food and mates. While some cell movement is random, directed movement stimulated by extracellular signals is our focus here. This involves a sequence of steps in which cells first detect extracellular chemical and/or mechanical signals via membrane receptors that activate signal transduction cascades and produce intracellular signals. These intracellular signals control the motile machinery of the cell and thereby determine the spatial localization of the sites of force generation needed to produce directed motion. Understanding how force generation within cells and mechanical interactions with their surroundings, including other cells, are controlled in space and time to produce cell-level movement is a major challenge, and involves many issues that are amenable to mathematical modelling.

Signal-regulated oxidation of proteins via MICAL

2020 ◽  
Vol 48 (2) ◽  
pp. 613-620
Author(s):  
Clara Ortegón Salas ◽  
Katharina Schneider ◽  
Christopher Horst Lillig ◽  
Manuela Gellert
Keyword(s):  
Signal Transduction ◽  
Hydrogen Peroxide ◽  
Cell Death ◽  
Redox Regulation ◽  
Signal Transduction Pathways ◽  
Cellular Functions ◽  
Intracellular Signals ◽  
Amino Acid Side Chains ◽  
Specific Receptors ◽  
Sulfur Containing

Processing of and responding to various signals is an essential cellular function that influences survival, homeostasis, development, and cell death. Extra- or intracellular signals are perceived via specific receptors and transduced in a particular signalling pathway that results in a precise response. Reversible post-translational redox modifications of cysteinyl and methionyl residues have been characterised in countless signal transduction pathways. Due to the low reactivity of most sulfur-containing amino acid side chains with hydrogen peroxide, for instance, and also to ensure specificity, redox signalling requires catalysis, just like phosphorylation signalling requires kinases and phosphatases. While reducing enzymes of both cysteinyl- and methionyl-derivates have been characterised in great detail before, the discovery and characterisation of MICAL proteins evinced the first examples of specific oxidases in signal transduction. This article provides an overview of the functions of MICAL proteins in the redox regulation of cellular functions.

scholarly journals Dynein Light Chain 1 Regulates Dynamin-mediated F-Actin Assembly during Sperm Individualization in Drosophila

2005 ◽  
Vol 16 (7) ◽  
pp. 3107-3116 ◽  
Author(s):  
Anindya Ghosh-Roy ◽  
Bela S. Desai ◽  
Krishanu Ray
Keyword(s):  
Light Chain ◽  
Cytoplasmic Dynein ◽  
Actin Dynamics ◽  
Dynein Light Chain ◽  
Actin Assembly ◽  
Cellular Functions ◽  
Directed Movement ◽  
Cellular Processes ◽  
Dynactin Complex

Toward the end of spermiogenesis, spermatid nuclei are compacted and the clonally related spermatids individualize to become mature and active sperm. Studies in Drosophila showed that caudal end-directed movement of a microfilament-rich structure, called investment cone, expels the cytoplasmic contents of individual spermatids. F-actin dynamics plays an important role in this process. Here we report that the dynein light chain 1 (DLC1) of Drosophila is involved in two separate cellular processes during sperm individualization. It is enriched around spermatid nuclei during postelongation stages and plays an important role in the dynein-dynactin–dependent rostral retention of the nuclei during this period. In addition, DDLC1 colocalizes with dynamin along investment cones and regulates F-actin assembly at this organelle by retaining dynamin along the cones. Interestingly, we found that this process does not require the other subunits of cytoplasmic dynein-dynactin complex. Altogether, these observations suggest that DLC1 could independently regulate multiple cellular functions and established a novel role of this protein in F-actin assembly in Drosophila.

scholarly journals F-actin-dependent Translocation of the Rap1 GDP/GTP Exchange Factor RasGRP2

2004 ◽  
Vol 279 (19) ◽  
pp. 20435-20446 ◽  
Author(s):  
Mariía J. Caloca ◽  
José L. Zugaza ◽  
Miguel Vicente-Manzanares ◽  
Francisco Sánchez-Madrid ◽  
Xosé R. Bustelo
Keyword(s):  
Signal Transduction ◽  
Amino Acids ◽  
Subcellular Distribution ◽  
Actin Polymerization ◽  
Biological Effects ◽  
Actin Dynamics ◽  
Exchange Factor ◽  
Common Structure ◽  
Direct Association ◽  
P21 Activated Kinase

RasGRPs constitute a new group of diacylglycerol-dependent GDP/GTP exchange factors that activate Ras subfamily GTPases. Despite a common structure, Ras-GRPs diverge in their GTPase specificity, subcellular distribution, and downstream biological effects. The more divergent family member is RasGRP2, a Rap1-specific exchange factor with low affinity toward diacylglycerol. The regulation of RasGRP2 during signal transduction has remained elusive up to now. In this report, we show that the subcellular localization of Ras-GRP2 is highly dependent on actin dynamics. Thus, the induction of F-actin by cytoskeletal regulators such as Vav, Vav2, Dbl, and Rac1 leads to the shift of RasGRP2 from the cytosol to membrane ruffles and its co-localization with F-actin. Treatment of cells with cytoskeletal disrupting drugs abolishes this effect, leading to an abnormal localization of RasGRP2 in cytoplasmic clusters of actin. The use of Rac1 effector mutants indicates that the RasGRP2 translocation is linked exclusively to actin polymerization and is independent of other pathways such as p21-activated kinase JNK, or superoxide production. Biochemical experiments demonstrate that the translocation of RasGRP2 to membrane ruffles is mediated by the direct association of this protein with F-actin, a property contained within its 150 first amino acids. Finally, we show that the RasGRP2/F-actin interaction promotes the regionalized activation of Rap1 in juxtamembrane areas of the cell. These results reveal a novel function of the actin cytoskeleton in mediating the spatial activation of Ras subfamily GTPases through the selective recruitment of GDP/GTP exchange factors.

Mechanisms of Hormone Action

2011 ◽  
Author(s):  
Stephen R. Hammes ◽  
Carole R. Mendelson
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Nuclear Receptors ◽  
Plasma Membranes ◽  
Hormone Receptors ◽  
Membrane Receptors ◽  
Endocrine Disorders ◽  
Messenger Rnas ◽  
Dihydroxyvitamin D3 ◽  
Transduction Mechanisms

The capacity of a cell to respond to a particular hormone depends on the presence of cellular receptors specific for that hormone. After binding hormone, the receptor is biochemically and structurally altered, resulting in its activation; the activated receptor then mediates all of the actions of the hormone on the cell. The steroid and thyroid hormones as well as retinoids and 1,25-dihydroxyvitamin D3 diffuse freely through the lipophilic plasma membrane of the cell and interact with receptors that are primarily within the nucleus. On activation, the receptors alter the transcription of specific genes, resulting in changes in the levels of specific messenger RNAs (mRNAs), which are in turn translated into proteins. Hormones that are water soluble, such as the peptide and polypeptide hormones, catecholamines, and other neurotransmitters, as well as the relatively hydrophobic prostaglandins, interact with receptors in the plasma membrane. After hormone binding, the activated membrane receptors initiate signal transduction cascades that result in changes in enzyme activities and alterations in gene expression. In this chapter, the properties of various classes of receptors that are localized within the plasma membranes of target cells and the signal transduction mechanisms that mediate interactions with their ligands will first be addressed. This will be followed by consideration of the structural properties of the nuclear hormone receptors, the events that result in their activation, and the mechanisms whereby the activated nuclear receptors alter the expression of specific genes. Finally, a number of endocrine disorders that are caused by alterations in the number and/or function of plasma membranes and nuclear receptors will be reviewed. The function of a receptor is to recognize a particular hormone among all the molecules in the environment of the cell at a given time and, after binding the hormone, to transmit a signal that ultimately results in a biological response. Hormones are normally present in the circulation in extremely low concentrations, ranging from 10 –9 to 10 –11 M.

scholarly journals Dynamic microtubules regulate cellular contractility during T-cell activation

2017 ◽  
Vol 114 (21) ◽  
pp. E4175-E4183 ◽  
Author(s):  
King Lam Hui ◽  
Arpita Upadhyaya
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Adaptive Immune Response ◽  
Cell Receptor ◽  
Force Generation ◽  
Actin Dynamics ◽  
Bipolar Filament

T-cell receptor (TCR) triggering and subsequent T-cell activation are essential for the adaptive immune response. Recently, multiple lines of evidence have shown that force transduction across the TCR complex is involved during TCR triggering, and that the T cell might use its force-generation machinery to probe the mechanical properties of the opposing antigen-presenting cell, giving rise to different signaling and physiological responses. Mechanistically, actin polymerization and turnover have been shown to be essential for force generation by T cells, but how these actin dynamics are regulated spatiotemporally remains poorly understood. Here, we report that traction forces generated by T cells are regulated by dynamic microtubules (MTs) at the interface. These MTs suppress Rho activation, nonmuscle myosin II bipolar filament assembly, and actin retrograde flow at the T-cell–substrate interface. Our results suggest a novel role of the MT cytoskeleton in regulating force generation during T-cell activation.

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