scholarly journals Membrane mechanics govern spatiotemporal heterogeneity of endocytic clathrin coat dynamics

2017 ◽  
Vol 28 (24) ◽  
pp. 3480-3488 ◽  
Author(s):  
N. M. Willy ◽  
J. P. Ferguson ◽  
S. D. Huber ◽  
S. P. Heidotting ◽  
E. Aygün ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Morphological Changes ◽  
Cell Types ◽  
Membrane Tension ◽  
Membrane Mechanics ◽  
Cellular Processes ◽  
Spatiotemporal Heterogeneity ◽  
Multicellular Organisms ◽  
Different Cell Types

Dynamics of endocytic clathrin-coated structures can be remarkably divergent across different cell types, cells within the same culture, or even distinct surfaces of the same cell. The origin of this astounding heterogeneity remains to be elucidated. Here we show that cellular processes associated with changes in effective plasma membrane tension induce significant spatiotemporal alterations in endocytic clathrin coat dynamics. Spatiotemporal heterogeneity of clathrin coat dynamics is also observed during morphological changes taking place within developing multicellular organisms. These findings suggest that tension gradients can lead to patterning and differentiation of tissues through mechanoregulation of clathrin-mediated endocytosis.

scholarly journals Mechanics of spreading cells probed by atomic force microscopy

Open Biology ◽  
2013 ◽  
Vol 3 (7) ◽  
pp. 130084 ◽  
Author(s):  
Anna Pietuch ◽  
Andreas Janshoff
Keyword(s):  
Plasma Membrane ◽  
Single Cell ◽  
Morphological Changes ◽  
Cellular Adhesion ◽  
Membrane Tension ◽  
Membrane Mechanics ◽  
Cellular Mechanics ◽  
Membrane Area ◽  
Atomic Force ◽  
Initial Adhesion

Cellular adhesion and motility are fundamental processes in biological systems such as morphogenesis and tissue homeostasis. During these processes, cells heavily rely on the ability to deform and supply plasma membrane from pre-existing membrane reservoirs, allowing the cell to cope with substantial morphological changes. While morphological changes during single cell adhesion and spreading are well characterized, the accompanying alterations in cellular mechanics are scarcely addressed. Using the atomic force microscope, we measured changes in cortical and plasma membrane mechanics during the transition from early adhesion to a fully spread cell. During the initial adhesion step, we found that tremendous changes occur in cortical and membrane tension as well as in membrane area. Monitoring the spreading progress by means of force measurements over 2.5 h reveals that cortical and membrane tension become constant at the expense of excess membrane area. This was confirmed by fluorescence microscopy, which shows a rougher plasma membrane of cells in suspension compared with spread ones, allowing the cell to draw excess membrane from reservoirs such as invaginations or protrusions while attaching to the substrate and forming a first contact zone. Concretely, we found that cell spreading is initiated by a transient drop in tension, which is compensated by a decrease in excess area. Finally, all mechanical parameters become almost constant although morphological changes continue. Our study shows how a single cell responds to alterations in membrane tension by adjusting its overall membrane area. Interference with cytoskeletal integrity, membrane tension and excess surface area by administration of corresponding small molecular inhibitors leads to perturbations of the spreading process.

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin
Keyword(s):  
Dna Sequences ◽  
Cell Types ◽  
Transcription Terminator ◽  
Response Elements ◽  
Polycomb Response Elements ◽  
The Individual ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

scholarly journals The organisation and functions of local Ca2+ signals

2001 ◽  
Vol 114 (12) ◽  
pp. 2213-2222 ◽  
Author(s):  
Martin D. Bootman ◽  
Peter Lipp ◽  
Michael J. Berridge
Keyword(s):  
Cell Proliferation ◽  
Gene Transcription ◽  
Cell Biology ◽  
Building Blocks ◽  
Cell Types ◽  
Diverse Range ◽  
Cellular Processes ◽  
Different Cell Types ◽  
Intracellular Messenger ◽  
Sensory Mechanisms

Calcium (Ca2+) is a ubiquitous intracellular messenger, controlling a diverse range of cellular processes, such as gene transcription, muscle contraction and cell proliferation. The ability of a simple ion such as Ca2+ to play a pivotal role in cell biology results from the facility that cells have to shape Ca2+ signals in space, time and amplitude. To generate and interpret the variety of observed Ca2+ signals, different cell types employ components selected from a Ca2+ signalling ‘toolkit’, which comprises an array of homeostatic and sensory mechanisms. By mixing and matching components from the toolkit, cells can obtain Ca2+ signals that suit their physiology. Recent studies have demonstrated the importance of local Ca2+ signals in defining the specificity of the interaction of Ca2+ with its targets. Furthermore, local Ca2+ signals are the triggers and building blocks for larger global signals that propagate throughout cells.

scholarly journals A systems perspective of heterocellular signaling

2018 ◽  
Vol 62 (4) ◽  
pp. 607-617 ◽  
Author(s):  
Alan Wells ◽  
H. Steven Wiley
Keyword(s):  
Cell Types ◽  
Regulatory Processes ◽  
Technical Developments ◽  
Building Models ◽  
Realistic Description ◽  
Multiple Cell ◽  
Solid Foundation ◽  
And Function ◽  
Multicellular Organisms ◽  
Different Cell Types

Signal exchange between different cell types is essential for development and function of multicellular organisms, and its dysregulation is causal in many diseases. Unfortunately, most cell-signaling work has employed single cell types grown under conditions unrelated to their native context. Recent technical developments have started to provide the tools needed to follow signaling between multiple cell types, but gaps in the information they provide have limited their usefulness in building realistic models of heterocellular signaling. Currently, only targeted assays have the necessary sensitivity, selectivity, and spatial resolution to usefully probe heterocellular signaling processes, but these are best used to test specific, mechanistic models. Decades of systems biology research with monocultures has provided a solid foundation for building models of heterocellular signaling, but current models lack a realistic description of regulated proteolysis and the feedback processes triggered within and between cells. Identification and understanding of key regulatory processes in the extracellular environment and of recursive signaling patterns between cells will be essential to building predictive models of heterocellular systems.

Specific binding of [3H]oxytocin in the female rat brain

1983 ◽  
Vol 61 (9) ◽  
pp. 989-995 ◽  
Author(s):  
B. M. Ferrier ◽  
S.A. McClorry ◽  
A. W. Cochrane
Keyword(s):  
Plasma Membrane ◽  
Limbic System ◽  
Microsomal Fraction ◽  
Specific Binding ◽  
Cell Types ◽  
Time Dependent ◽  
Female Rat ◽  
Ph Optimum ◽  
Rat Tissue ◽  
Different Cell Types

Because of demonstrated effects of oxytocin on some limbic system mediated behaviours, the specific binding of [3H]oxytocin to a plasma membrane containing fraction of rat limbic tissue has been studied. The binding of the microsomal fraction of estrogenized, female rat tissue was time dependent and saturable, with a Bmax of 2.5 × 10−l3 moles per milligram of protein and an apparent KD of 3.53 × 10−8 M, and appeared to show positive cooperativity. The pH optimum of the binding was 6.0, close to the pH optimum for oxytocin – neurophysin binding; however, other results show the two types of binding to be different. The microsomal fraction did not appreciably degrade oxytocin under the conditions used for [3H]oxytocin binding. The distribution in limbic tissue of oxytocin-degrading activity and of individual enzymes capable of degrading oxytocin has been examined and an interplay of enzymes concentrated in different cell types is proposed.

scholarly journals Recent Experiments Support a Microemulsion Origin of Plasma Membrane Domains: Dependence of Domain Size on Physical Parameters

Membranes ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 167
Author(s):  
David W. Allender ◽  
M. Schick
Keyword(s):  
Plasma Membrane ◽  
Domain Size ◽  
Cell Types ◽  
Physical Parameters ◽  
Spontaneous Curvature ◽  
Membrane Domains ◽  
Physical Origin ◽  
Unsaturated Lipids ◽  
Bending Modulus ◽  
Different Cell Types

It is widely, but not universally, believed that the lipids of the plasma membrane are not uniformly distributed, but that “rafts” of sphingolipids and cholesterol float in a “sea” of unsaturated lipids. The physical origin of such heterogeneities is often attributed to a phase coexistence between the two different domains. We argue that this explanation is untenable for several reasons. Further, we note that the results of recent experiments are inconsistent with this picture. However, they are quite consistent with an alternate explanation, namely, that the plasma membrane is a microemulsion of the two kinds of regions. To show this, we briefly review a simplified version of this theory and its phase diagram. We also explicate the dependence of the predicted domain size on four physical parameters. They are the energy cost of gradients in the composition, the spontaneous curvature of the membrane, its bending modulus and its surface tension. Taking values of the latter two from experiment, we obtain domain sizes for several different cell types that vary from 58 to 88 nm.

scholarly journals The Heterocyst-Specific NsiR1 Small RNA Is an Early Marker of Cell Differentiation in Cyanobacterial Filaments

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Alicia M. Muro-Pastor
Keyword(s):  
Small Rna ◽  
Single Cells ◽  
Nitrogen Deficiency ◽  
Cell Types ◽  
Nitrogen Fixing ◽  
Vegetative Cells ◽  
Early Marker ◽  
Multicellular Organisms ◽  
Pcc 7120 ◽  
Different Cell Types

ABSTRACT Differentiation of single cells along filaments of cyanobacteria constitutes one of the simplest developmental patterns in nature. In response to nitrogen deficiency, certain cells located in a semiregular pattern along filaments differentiate into specialized nitrogen-fixing cells called heterocysts. The process involves the sequential activation of many genes whose expression takes place, either exclusively or at least more strongly, in those cells undergoing differentiation. In the model cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120, increased transcription of hetR, considered the earliest detectable heterocyst-specific transcript, has been reported to occur in pairs or even in clusters of cells, thus making it difficult to identify prospective heterocysts during the early stages of differentiation, before any morphological change is detectable. The promoter of nsiR1 (nitrogen stress inducible RNA1), a heterocyst-specific small RNA, constitutes a minimal sequence promoting heterocyst-specific transcription. Using confocal fluorescence microscopy, I have analyzed expression of a gfp reporter transcriptionally fused to P nsiR1 . The combined analysis of green fluorescence (reporting transcriptional activity from P nsiR1 ) and red fluorescence (an indication of progress in the differentiation of individual cells) shows that expression of P nsiR1 takes place in single cells located in a semiregular pattern before any other morphological or fluorescence signature of differentiation can be observed, thus providing an early marker for cells undergoing differentiation. IMPORTANCE Cyanobacterial filaments containing heterocysts constitute an example of bacterial division of labor. When using atmospheric nitrogen, these filaments behave as multicellular organisms in which two different cell types (vegetative cells and nitrogen-fixing heterocysts) coexist and cooperate to achieve growth of the filament as a whole. The molecular basis governing the differentiation of individual vegetative cells, and thus the establishment of a one-dimensional pattern from cells that are apparently the same, remains one of the most intriguing aspects of this differentiation process. Recent evidence suggests that, at any given time, some cells in the filaments are more likely than others to become heterocysts when nitrogen limitation is encountered. The robust heterocyst-specific nsiR1 promoter, which is induced very early during differentiation, provides a valuable tool to analyze issues such as early candidacy or the possible role of transcriptional noise in determining the fate of specific cells in cyanobacterial filaments.

scholarly journals Functional annotation of lncRNA in high-throughput screening

2021 ◽  
Author(s):  
Chi Wai Yip ◽  
Divya M. Sivaraman ◽  
Anika V. Prabhu ◽  
Jay W. Shin
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Functional Annotation ◽  
Cell Types ◽  
Specific Expression ◽  
Functional Roles ◽  
Cellular Processes ◽  
Cell Type Specific Expression ◽  
Cell Type Specific ◽  
Different Cell Types

Abstract Recent efforts on the characterization of long non-coding RNAs (lncRNAs) revealed their functional roles in modulating diverse cellular processes. These include pluripotency maintenance, lineage commitment, carcinogenesis, and pathogenesis of various diseases. By interacting with DNA, RNA and protein, lncRNAs mediate multifaceted mechanisms to regulate transcription, RNA processing, RNA interference and translation. Of more than 173000 discovered lncRNAs, the majority remain functionally unknown. The cell type-specific expression and localization of the lncRNA also suggest potential distinct functions of lncRNAs across different cell types. This highlights the niche of identifying functional lncRNAs in different biological processes and diseases through high-throughput (HTP) screening. This review summarizes the current work performed and perspectives on HTP screening of functional lncRNAs where different technologies, platforms, cellular responses and the downstream analyses are discussed. We hope to provide a better picture in applying different technologies to facilitate functional annotation of lncRNA efficiently.

scholarly journals Complex transcriptional regulation and independent evolution of fungal-like traits in a relative of animals

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Alex de Mendoza ◽  
Hiroshi Suga ◽  
Jon Permanyer ◽  
Manuel Irimia ◽  
Iñaki Ruiz-Trillo
Keyword(s):  
Cell Types ◽  
Cell Type ◽  
Dynamic Regulation ◽  
Transcriptional Dynamics ◽  
Genome Regulation ◽  
A Cell ◽  
Cell Type Specific ◽  
Gene Modules ◽  
Multicellular Organisms ◽  
Different Cell Types

Cell-type specification through differential genome regulation is a hallmark of complex multicellularity. However, it remains unclear how this process evolved during the transition from unicellular to multicellular organisms. To address this question, we investigated transcriptional dynamics in the ichthyosporean Creolimax fragrantissima, a relative of animals that undergoes coenocytic development. We find that Creolimax utilizes dynamic regulation of alternative splicing, long inter-genic non-coding RNAs and co-regulated gene modules associated with animal multicellularity in a cell-type specific manner. Moreover, our study suggests that the different cell types of the three closest animal relatives (ichthyosporeans, filastereans and choanoflagellates) are the product of lineage-specific innovations. Additionally, a proteomic survey of the secretome reveals adaptations to a fungal-like lifestyle. In summary, the diversity of cell types among protistan relatives of animals and their complex genome regulation demonstrates that the last unicellular ancestor of animals was already capable of elaborate specification of cell types.

Transcytosis: Crossing Cellular Barriers

2003 ◽  
Vol 83 (3) ◽  
pp. 871-932 ◽  
Author(s):  
PAMELA L. TUMA ◽  
ANN L. HUBBARD
Keyword(s):  
Cell Types ◽  
In Vitro Models ◽  
Vesicle Traffic ◽  
Fundamental Process ◽  
A Cell ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Transport Of Macromolecules

Tuma, Pamela L., and Ann L. Hubbard. Transcytosis: Crossing Cellular Barriers. Physiol Rev 83: 871–932, 2003; 10.1152/physrev.00001.2003.—Transcytosis, the vesicular transport of macromolecules from one side of a cell to the other, is a strategy used by multicellular organisms to selectively move material between two environments without altering the unique compositions of those environments. In this review, we summarize our knowledge of the different cell types using transcytosis in vivo, the variety of cargo moved, and the diverse pathways for delivering that cargo. We evaluate in vitro models that are currently being used to study transcytosis. Caveolae-mediated transcytosis by endothelial cells that line the microvasculature and carry circulating plasma proteins to the interstitium is explained in more detail, as is clathrin-mediated transcytosis of IgA by epithelial cells of the digestive tract. The molecular basis of vesicle traffic is discussed, with emphasis on the gaps and uncertainties in our understanding of the molecules and mechanisms that regulate transcytosis. In our view there is still much to be learned about this fundamental process.

Sign in / Sign up

Export Citation Format

Share Document