scholarly journals The 'lipid raft' microdomain proteins reggie-1 and reggie-2 (flotillins) are scaffolds for protein interaction and signalling.

2005 ◽  
Vol 72 ◽  
pp. 109-118 ◽  
Author(s):  
Claudia A. O. Stuermer ◽  
Helmut Plattner
Keyword(s):  
Plasma Membrane ◽  
Lipid Raft ◽  
Ganglion Cells ◽  
Single Cells ◽  
Cell Types ◽  
Cellular Prion Protein ◽  
Surface Proteins ◽  
Current View ◽  
Specific Cell ◽  
Rna Knockdown

Reggie-1 and reggie-2 are two evolutionarily highly conserved proteins which are up-regulated in retinal ganglion cells during regeneration of lesioned axons in the goldfish optic nerve. They are located at the cytoplasmic face of the plasma membrane and are considered to be 'lipid raft' constituents due to their insolubility in Triton X-100 and presence in the 'floating fractions'; hence they were independently named flotillins. According to our current view, the reggies subserve functions as protein scaffolds which form microdomains in neurons, lymphocytes and many other cell types across species as distant as flies and humans. These microdomains are of a surprisingly constant size of less than or equal to 0.1 mm in all cell types, whereas the distance between them is variable. The microdomains co-ordinate signal transduction of specific cell-surface proteins and especially of GPI (glycosylphosphatidylinositol)-anchored proteins into the cell, as is demonstrated for PrPc (cellular prion protein) in T-lymphocytes. These cells possess a pre-formed reggie cap scaffold consisting of densely packed reggie microdomains. PrPc is targeted to the lymphocyte reggie cap when activated by antibody cross-linking, and induces a distinct Ca2+ signal. In developing zebrafish, reggies become concentrated in neurons and axon tracts, and their absence, after morpholino antisense RNA-knockdown, results in deformed embryos with reduced brains. Likewise, defects in Drosophila eye morphogenesis occur upon reggie overexpression in mutant flies. The defects observed in the organism, as well as in single cells in culture, indicate a morphogenetic function of the reggies, with emphasis on the nervous system. This complies with their role as scaffolds for the formation of multiprotein complexes involved in signalling across the plasma membrane.

Vertebrate retinal ganglion cells are selected from competent progenitors by the action of Notch

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3637-3650 ◽  
Author(s):  
C.P. Austin ◽  
D.E. Feldman ◽  
J.A. Ida ◽  
C.L. Cepko
Keyword(s):  
Cell Fate ◽  
Ganglion Cells ◽  
Notch Pathway ◽  
Cell Types ◽  
Projection Neurons ◽  
Specific Cell ◽  
Vitro Assay ◽  
Notch Activity

The first cells generated during development of the vertebrate retina are the ganglion cells, the projection neurons of the retina. Although they are one of the most intensively studied cell types within the central nervous system, little is known of the mechanisms that determine ganglion cell fate. We demonstrate that ganglion cells are selected from a large group of competent progenitors that comprise the majority of the early embryonic retina and that differentiation within this group is regulated by Notch. Notch activity in vivo was diminished using antisense oligonucleotides or augmented using a retrovirally transduced constitutively active allele of Notch. The number of ganglion cells produced was inversely related to the level of Notch activity. In addition, the Notch ligand Delta inhibited retinal progenitors from differentiating as ganglion cells to the same degree as did activated Notch in an in vitro assay. These results suggest a conserved strategy for neurogenesis in the retina and describe a versatile in vitro and in vivo system with which to examine the action of the Notch pathway in a specific cell fate decision in a vertebrate.

scholarly journals Self-reporting transposons enable simultaneous readout of gene expression and transcription factor binding in single cells

2019 ◽  
Author(s):  
Arnav Moudgil ◽  
Michael N. Wilkinson ◽  
Xuhua Chen ◽  
June He ◽  
Alex J. Cammack ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Single Cell ◽  
Binding Sites ◽  
Expression Profiles ◽  
Single Cells ◽  
Gene Expression Profiles ◽  
Cell Types ◽  
Specific Cell

AbstractIn situ measurements of transcription factor (TF) binding are confounded by cellular heterogeneity and represent averaged profiles in complex tissues. Single cell RNA-seq (scRNA-seq) is capable of resolving different cell types based on gene expression profiles, but no technology exists to directly link specific cell types to the binding pattern of TFs in those cell types. Here, we present self-reporting transposons (SRTs) and their use in single cell calling cards (scCC), a novel assay for simultaneously capturing gene expression profiles and mapping TF binding sites in single cells. First, we show how the genomic locations of SRTs can be recovered from mRNA. Next, we demonstrate that SRTs deposited by the piggyBac transposase can be used to map the genome-wide localization of the TFs SP1, through a direct fusion of the two proteins, and BRD4, through its native affinity for piggyBac. We then present the scCC method, which maps SRTs from scRNA-seq libraries, thus enabling concomitant identification of cell types and TF binding sites in those same cells. As a proof-of-concept, we show recovery of cell type-specific BRD4 and SP1 binding sites from cultured cells. Finally, we map Brd4 binding sites in the mouse cortex at single cell resolution, thus establishing a new technique for studying TF biology in situ.

scholarly journals Prion Protein in Stem Cells: A Lipid Raft Component Involved in the Cellular Differentiation Process

2020 ◽  
Vol 21 (11) ◽  
pp. 4168 ◽  
Author(s):  
Stefano Martellucci ◽  
Costantino Santacroce ◽  
Francesca Santilli ◽  
Valeria Manganelli ◽  
Maurizio Sorice ◽  
...  
Keyword(s):  
Stem Cells ◽  
Prion Protein ◽  
Lipid Raft ◽  
Cellular Differentiation ◽  
Cell Types ◽  
Pleiotropic Effect ◽  
Cellular Prion Protein ◽  
Differentiation Process ◽  
Differentiation Degree

The prion protein (PrP) is an enigmatic molecule with a pleiotropic effect on different cell types; it is localized stably in lipid raft microdomains and it is able to recruit downstream signal transduction pathways by its interaction with various biochemical partners. Since its discovery, this lipid raft component has been involved in several functions, although most of the publications focused on the pathological role of the protein. Recent studies report a key role of cellular prion protein (PrPC) in physiological processes, including cellular differentiation. Indeed, the PrPC, whose expression is modulated according to the cell differentiation degree, appears to be part of the multimolecular signaling pathways of the neuronal differentiation process. In this review, we aim to summarize the main findings that report the link between PrPC and stem cells.

Morphological and functional identifications of catfish retinal neurons. I. Classical morphology

1975 ◽  
Vol 38 (1) ◽  
pp. 53-71 ◽  
Author(s):  
K. Naka ◽  
N. R. Garraway
Keyword(s):  
Ganglion Cells ◽  
Horizontal Cell ◽  
Dendritic Tree ◽  
Amacrine Cells ◽  
Cell Types ◽  
Bipolar Cells ◽  
Inner Nuclear Layer ◽  
Horizontal Cells ◽  
Specific Cell ◽  
Definition Of

The morphology of the catfish horizontal cells is comparable to that in other fish retinas. The external horizontal cells contact cone receptors and are stellate in shape; the intermediate horizontal cells are even more so and contact rod receptors. The internal horizontal cells constitute the most proximal layer of the inner nuclear layer and may possibly be, in reality, extended processes from the other two horizontal cell types. Bipolar cells resemble those in other teleost retinas: the size and shape of their dendritic tree encompass a continuous spectrum ranging from what is known as the small to the large bipolar cells. The accepted definition of amacrine cells is sufficiently vague to justify our originating a more descriptive and less inferential name for the (axonless) neurons in the inner nuclear layer which radiate processes throughout the inner synaptic layer. These starbust and spaghetti cells vary considerably in the character and extent of their dendritic spread, but correlates exist in other vertebrate retinas. Ganglion cells are found not only in the classical ganglion layer but displaced into the inner nuclear layer as well. Several types can be distinguished on the basis of cell geometry and by the properties of their dendritic tree. Not all of the categorization corresponds with previous descriptions; our findings suggest that some reorganization may be necessary in the accepted classification of cells in the proximal areas of the vertebrate retina. A subtle yet remarkable pattern underlies the entire structure of the catfish retina; there exists a definite gradient of size within a particular class of cells, and of configuration among the subclasses of a specific cell type. It remains to be seen if these morphological spectra bear any functional consequences. The fact that the structure of the catfish retina most closely resembles those of other phylogenetically ancient animals, such as the skate and the dogfish shark, testifies to its primitive organization; morphological and functional mechanisms discernible in this simple system may, therefore, be applicable to the retinas of higher ordered vertebrates.

Palmitoylation of prohibitin at cysteine 69 facilitates its membrane translocation and interaction with Eps 15 homology domain protein 2 (EHD2)

2010 ◽  
Vol 88 (3) ◽  
pp. 553-558 ◽  
Author(s):  
Sudharsana Rao Ande ◽  
Suresh Mishra
Keyword(s):  
Plasma Membrane ◽  
Cell Signaling ◽  
Signaling Pathways ◽  
Tyrosine Phosphorylation ◽  
Lipid Raft ◽  
Plasma Membranes ◽  
Cell Types ◽  
Membrane Translocation ◽  
Domain Protein ◽  
Cell Signaling Pathways

Plasma membrane translocation of specific cytosolic proteins plays an important role in cell signaling pathways. We have recently shown that prohibitin (PHB) , a protein present in the plasma membranes of various cell types, interacts with Eps 15 homology domain protein 2 (EHD2), a lipid raft protein. However, the mechanism involved in membrane translocation of PHB is not known.We report that PHB undergoes palmitoylation at cysteine 69 (Cys69), and that this palmitoylation is required for PHB's membrane translocation. Furthermore, we demonstrate that membrane translocation of PHB facilitates tyrosine phosphorylation and its interaction with EHD2. Thus, the palmitoylation and membrane translocation of PHB and its interaction with EHD2 may play a role in cell signaling.

scholarly journals Dependence of Adenovirus Infectivity on Length of the Fiber Shaft Domain

2000 ◽  
Vol 74 (22) ◽  
pp. 10274-10286 ◽  
Author(s):  
Dmitry M. Shayakhmetov ◽  
André Lieber
Keyword(s):  
Cell Types ◽  
Surface Proteins ◽  
Specific Cell ◽  
Shaft Length ◽  
Serotype 5 ◽  
Cell Adsorption ◽  
Major Attention ◽  
A Charge ◽  
Tissue Tropisms ◽  
Adenovirus Receptor

ABSTRACT One of the objectives in adenovirus (Ad) vector development is to target gene delivery to specific cell types. Major attention has been given to modification of the Ad fiber knob, which is thought to determine virus tropism. However, among the human Ad serotypes with different tissue tropisms, not only the knob but also the length of the fiber shaft domain varies significantly. In this study we attempted to delineate the role of fiber length in coxsackievirus-adenovirus receptor (CAR)- and non-CAR-mediated infection. A series of Ad serotype 5 (Ad5) capsid-based vectors containing long or short fibers with knob domains derived from Ad5, Ad9, or Ad35 was constructed and tested in adsorption, internalization, and transduction studies. For Ad5 or Ad9 knob-possessing vectors, a long-shafted fiber was critical for efficient adsorption/internalization and transduction of CAR/αv integrin-expressing cells. Ad5 capids containing short CAR-recognizing fibers were affected in cell adsorption and infection. In contrast, for the chimeric vectors possessing Ad35 knobs, which enter cells by a CAR/αv integrin-independent pathway, fiber shaft length had no significant influence on binding or infectibility on tested cells. The weak attachment of short-shafted Ad5 or Ad9 knob-possessing vectors seems to be causally associated with a charge-dependent repulsion between Ad5 capsid and acidic cell surface proteins. The differences between short- and long-shafted vectors in attachment or infection were abrogated by preincubation of cells with polycations. This study demonstrates that the fiber-CAR interaction is not the sole determinant for tropism of Ad vectors containing chimeric fibers. CAR- and αv integrin-mediated infections are influenced by other factors, including the length of the fiber shaft.

scholarly journals Depolarization-induced Calcium Responses in Sympathetic Neurons: Relative Contributions from Ca2+ Entry, Extrusion, ER/Mitochondrial Ca2+ Uptake and Release, and Ca2+ Buffering

2006 ◽  
Vol 129 (1) ◽  
pp. 29-56 ◽  
Author(s):  
Michael Patterson ◽  
James Sneyd ◽  
David D. Friel
Keyword(s):  
Plasma Membrane ◽  
Voltage Clamp ◽  
Diffusion Model ◽  
Time Course ◽  
Sympathetic Neurons ◽  
Cell Types ◽  
Specific Cell ◽  
Modeling Studies ◽  
Uniform Model ◽  
Uptake And Release

Many models have been developed to account for stimulus-evoked [Ca2+] responses, but few address how responses elicited in specific cell types are defined by the Ca2+ transport and buffering systems that operate in the same cells. In this study, we extend previous modeling studies by linking the time course of stimulus-evoked [Ca2+] responses to the underlying Ca2+ transport and buffering systems. Depolarization-evoked [Ca2+]i responses were studied in sympathetic neurons under voltage clamp, asking how response kinetics are defined by the Ca2+ handling systems expressed in these cells. We investigated five cases of increasing complexity, comparing observed and calculated responses deduced from measured Ca2+ handling properties. In Case 1, [Ca2+]i responses were elicited by small Ca2+ currents while Ca2+ transport by internal stores was inhibited, leaving plasma membrane Ca2+ extrusion intact. In Case 2, responses to the same stimuli were measured while mitochondrial Ca2+ uptake was active. In Case 3, responses were elicited as in Case 2 but with larger Ca2+ currents that produce larger and faster [Ca2+]i elevations. Case 4 included the mitochondrial Na/Ca exchanger. Finally, Case 5 included ER Ca2+ uptake and release pathways. We found that [Ca2+]i responses elicited by weak stimuli (Cases 1 and 2) could be quantitatively reconstructed using a spatially uniform model incorporating the measured properties of Ca2+ entry, removal, and buffering. Responses to strong depolarization (Case 3) could not be described by this model, but were consistent with a diffusion model incorporating the same Ca2+ transport and buffering descriptions, as long as endogenous buffers have low mobility, leading to steep radial [Ca2+]i gradients and spatially nonuniform Ca2+ loading by mitochondria. When extended to include mitochondrial Ca2+ release (Case 4) and ER Ca2+ transport (Case 5), the diffusion model could also account for previous measurements of stimulus-evoked changes in total mitochondrial and ER Ca concentration.

scholarly journals An alternative approach to produce versatile retinal organoids with accelerated ganglion cell development

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philip E. Wagstaff ◽  
Anneloor L. M. A. ten Asbroek ◽  
Jacoline B. ten Brink ◽  
Nomdo M. Jansonius ◽  
Arthur A. B. Bergen
Keyword(s):  
Ganglion Cells ◽  
Cell Types ◽  
Retinal Cell ◽  
Specific Cell ◽  
Retinal Ganglion ◽  
In Vivo Models ◽  
Alternative Approach

AbstractGenetically complex ocular neuropathies, such as glaucoma, are a major cause of visual impairment worldwide. There is a growing need to generate suitable human representative in vitro and in vivo models, as there is no effective treatment available once damage has occured. Retinal organoids are increasingly being used for experimental gene therapy, stem cell replacement therapy and small molecule therapy. There are multiple protocols for the development of retinal organoids available, however, one potential drawback of the current methods is that the organoids can take between 6 weeks and 12 months on average to develop and mature, depending on the specific cell type wanted. Here, we describe and characterise a protocol focused on the generation of retinal ganglion cells within an accelerated four week timeframe without any external small molecules or growth factors. Subsequent long term cultures yield fully differentiated organoids displaying all major retinal cell types. RPE, Horizontal, Amacrine and Photoreceptors cells were generated using external factors to maintain lamination.

scholarly journals ProtAnno, an Automated Cell Type Annotation Tool for Single Cell Proteomics Data that Integrates Information from Multiple Reference Sources

2021 ◽  
Author(s):  
Wenxuan Deng ◽  
Biqing Zhu ◽  
Seyoung Park ◽  
Tomokazu S. Sumida ◽  
Avraham Unterman ◽  
...  
Keyword(s):  
Single Cell ◽  
Single Cells ◽  
Earth Metal ◽  
Cell Types ◽  
Specific Cell ◽  
Cell Type ◽  
Proteomics Data ◽  
Data Annotation ◽  
Different Cell Types ◽  
Unique Molecular Identifier

Compared with sequencing-based global genomic profiling, cytometry labels targeted surface markers on millions of cells in parallel either by conjugated rare earth metal particles or Unique Molecular Identifier (UMI) barcodes. Correct annotation of these cells to specific cell types is a key step in the analysis of these data. However, there is no computational tool that automatically annotates single cell proteomics data for cell type inference. In this manuscript, we propose an automated single cell proteomics data annotation approach called ProtAnno to facilitate cell type assignments without laborious manual gating. ProtAnno is designed to incorporate information from annotated single cell RNA-seq (scRNA-seq), CITE-seq, and prior data knowledge (which can be imprecise) on biomarkers for different cell types. We have performed extensive simulations to demonstrate the accuracy and robustness of ProtAnno. For several single cell proteomics datasets that have been manually labeled, ProtAnno was able to correctly label most single cells. In summary, ProtAnno offers an accurate and robust tool to automate cell type annotations for large single cell proteomics datasets, and the analysis of such annotated cell types can offer valuable biological insights.

Cell contact induces multiple types of electrical excitability from ascidian two-cell embryos that are cleavage arrested and contain all cell fate determinants

2007 ◽  
Vol 293 (5) ◽  
pp. R1976-R1996
Author(s):  
Motoko Tanaka-Kunishima ◽  
Kunitaro Takahashi ◽  
Fumiyuki Watanabe
Keyword(s):  
Stem Cells ◽  
Cell Fate ◽  
Single Cells ◽  
Muscle Cells ◽  
Cell Types ◽  
Specific Cell ◽  
Cell Type ◽  
Cell Pair ◽  
Fate Determinants ◽  
Cell Fate Determinants

Ascidian early embryonic cells undergo cell differentiation without cell cleavage, thus enabling mixture of cell fate determinants in single cells, which will not be possible in mammalian systems. Either cell in a two-cell embryo (2C cell) has multiple fates and develops into any cell types in a tadpole. To find the condition for controlled induction of a specific cell type, cleavage-arrested cell triplets were prepared in various combinations. They were 2C cells in contact with a pair of anterior neuroectoderm cells from eight-cell embryos (2C-aa triplet), with a pair of presumptive notochordal neural cells (2C-AA triplet), with a pair of presumptive posterior epidermal cells (2C-bb triplet), and with a pair of presumptive muscle cells (2C-BB triplet). The fate of the 2C cell was electrophysiologically identified. When two-cell embryos had been fertilized 3 h later than eight-cell embryos and triplets were formed, the 2C cells became either anterior-neuronal, posterior-neuronal or muscle cells, depending on the cell type of the contacting cell pair. When two-cell embryos had been fertilized earlier than eight-cell embryos, most 2C cells became epidermal. When two- and eight-cell embryos had been simultaneously fertilized, the 2C cells became any one of three cell types described above or the epidermal cell type. Differentiation of the ascidian 2C cell into major cell types was reproducibly induced by selecting the type of contacting cell pair and the developmental time difference between the contacting cell pair and 2C cell. We discuss similarities between cleavage-arrested 2C cells and vertebrate embryonic stem cells and propose the ascidian 2C cell as a simple model for toti-potent stem cells.

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