Target-independent regulation of a novel growth associated protein in the visual system of the chicken

Development ◽  
1990 ◽  
Vol 109 (2) ◽  
pp. 395-409 ◽  
Author(s):  
B. Schlosshauer ◽  
D. Dutting ◽  
M. Wild
Keyword(s):  
Ganglion Cell ◽  
Ganglion Cells ◽  
Antigen Expression ◽  
Subcellular Fractionation ◽  
Axonal Outgrowth ◽  
Control Of Gene Expression ◽  
Chick Retina ◽  
Retinal Axons

Using an immunosuppression technique, the monoclonal antibody 2A1 has been generated specific for a 140 × 10(3) Mr cytoplasmic-membrane-associated protein as shown by subcellular fractionation and Western blot analysis. The antigen is initially confined to perikarya of postmitotic migratory ganglion cells of the embryonic chick retina as revealed by bromodeoxyuridine labeling. During the subsequent period of axon outgrowth, the antigen becomes restricted to ganglion cell axons but disappears during the innervation of the tectum opticum, suggesting a tectal inhibition of antigen expression in retinal axons. To analyse whether the tectum suppresses 2A1-antigen expression, optic nerves of chick embryos were severed to prevent tectal innervation. 2A1-immunoreactivity was determined in deflected axons in comparison to control axons. In addition, retinal axons were grown in vitro on a substratum consisting of alternating stripes of laminin and tectal membranes, in order to investigate whether retinal axons become devoid of the 2A1-antigen once they cross from laminin to tectal membranes. However, neither prevention of target innervation by optic nerve transection in vivo nor exposure of retinal axons to soluble or particulate tectal components in vitro modify 2A1-antigen regulation in ganglion cell axons, suggesting a retina inherent-control of gene expression. Antigen expression is essentially restricted to the period of axonal outgrowth and therefore the 2A1-protein is likely to be involved in processes essential for neurite extension, independent of the synaptic target.

scholarly journals Precise tuning of gene expression output levels in mammalian cells

2018 ◽  
Author(s):  
Yale S. Michaels ◽  
Mike B. Barnkob ◽  
Hector Barbosa ◽  
Toni A. Baeumler ◽  
Mary K. Thompson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mammalian Cells ◽  
High Throughput Sequencing ◽  
Regulation Of Gene Expression ◽  
Antigen Expression ◽  
Control Of Gene Expression ◽  
Precise Control ◽  
Mouse Melanoma Model

ABSTRACTPrecise, analogue regulation of gene expression is critical for development, homeostasis and regeneration in mammals. In contrast, widely employed experimental and therapeutic approaches such as knock-in/out strategies are more suitable for binary control of gene activity, while RNA interference (RNAi) can lead to pervasive off-target effects and unpredictable levels of repression. Here we report on a method for the precise control of gene expression levels in mammalian cells based on engineered, synthetic microRNA response elements (MREs). To develop this system, we established a high-throughput sequencing approach for measuring the efficacy of thousands of miR-17 MRE variants. This allowed us to create a library of microRNA silencing-mediated fine-tuners (miSFITs) of varying strength that can be employed to control the expression of user specified genes. To demonstrate the value of this technology, we used a panel of miSFITs to tune the expression of a peptide antigen in a mouse melanoma model. This analysis revealed that antigen expression level is a key determinant of the anti-tumour immune response in vitro and in vivo. miSFITs are a powerful tool for modulating gene expression output levels with applications in research and cellular engineering.

scholarly journals Otx2 stimulates adult retinal ganglion cell regeneration

2020 ◽  
Author(s):  
Raoul Torero-Ibad ◽  
Nicole Quenech’du ◽  
Alain Prochiantz ◽  
Kenneth L. Moya
Keyword(s):  
Ganglion Cell ◽  
Cell Survival ◽  
Retinal Ganglion Cell ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Response To Stress ◽  
Retinal Ganglion Cell Survival ◽  
The Brain

AbstractRetinal ganglion cell axons provide the only link between the light sensitive and photon transducing neural retina and visual centers of the brain. Retinal ganglion cell axon degeneration occurs in a number of blinding diseases and the ability to stimulate axon regeneration from surviving ganglion cells could provide the anatomic substrate for restoration of vision. OTX2 is a homeoprotein transcription factor expressed in the retina and previous studies showed that, in response to stress, exogenous OTX2 increases the in vitro and in vivo survival of retinal ganglion cells. The present results show that, in addition to promoting adult retinal ganglion cell survival, OTX2 also stimulates the regeneration of their axons in vitro and in vivo. This dual activity of OTX2 on retinal ganglion cell survival and regeneration is of potential interest for degenerative diseases affecting this cell type.

scholarly journals PRESENCE OF A BASE LINE LEVEL OF SISTER CHROMATID EXCHANGES IN SOMATIC CELLS OF DROSOPHILA MELANOGASTER IN VIVO AND IN VITRO

Genetics ◽  
1982 ◽  
Vol 100 (2) ◽  
pp. 259-278
Author(s):  
Hideo Tsuji
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Ganglion Cells ◽  
Sister Chromatid Exchanges ◽  
Base Line ◽  
Cell Cycles ◽  
Chromatid Exchanges ◽  
Third Instar Larvae

ABSTRACT Sister chromatid exchanges (SCEs) under in vivo and in vitro conditions were examined in ganglion cells of third-instar larvae of Drosophila melanogaster (Oregon-R). In the in vivo experiment, third-instar larvae were fed on synthetic media containing 5-bromo-2′-deoxyuridine (BrdUrd). After two cell cycles, ganglia were dissected and treated with colchicine. In the in vitro experiment, the ganglia were also incubated in media containing BrdUrd for two cell cycles, and treated with colchicine. SCEs were scored in metaphase stained with Hoechst 33258 plus Giemsa. The frequencies of SCEs stayed constant in the range of 25-150 vg/ml and 0.25-2.5 vg/ml of BrdUrd in vivo and in vitro, respectively. SCEs gradually increased at higher concentrations, strongly suggesting that at least a fraction of the detected SCEs are spontaneous. The constant levels of SCE frequency were estimated, on the average, at 0.103 per cell per two cell cycles for females and 0.101 for males in vivo and at 0.096 for females and 0.091 for males in vitro. No difference was found in the SCE frequency between sexes at any of the BrdUrd concentrations. The analysis for the distribution of SCEs within chromosomes revealed an extraordinarily high proportion of the SCEs at the junctions between euchromatin and heterochromatin; the remaining SCEs were preferentially localized in the euchromatic regions of the chromosomes and in the heterochromatic Y chromosome. These results were largely inconsistent with those of Gatti et al. (1979).

scholarly journals Uptake and Distribution of Administered Bone Marrow Mesenchymal Stem Cell Extracellular Vesicles in Retina

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 730
Author(s):  
Biji Mathew ◽  
Leianne A. Torres ◽  
Lorea Gamboa Gamboa Acha ◽  
Sophie Tran ◽  
Alice Liu ◽  
...  
Keyword(s):  
Stem Cell ◽  
Mesenchymal Stem Cell ◽  
Extracellular Vesicles ◽  
Time Course ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Dependent Manner ◽  
Paracrine Effects

Cell replacement therapy using mesenchymal (MSC) and other stem cells has been evaluated for diabetic retinopathy and glaucoma. This approach has significant limitations, including few cells integrated, aberrant growth, and surgical complications. Mesenchymal Stem Cell Exosomes/Extracellular Vesicles (MSC EVs), which include exosomes and microvesicles, are an emerging alternative, promoting immunomodulation, repair, and regeneration by mediating MSC’s paracrine effects. For the clinical translation of EV therapy, it is important to determine the cellular destination and time course of EV uptake in the retina following administration. Here, we tested the cellular fate of EVs using in vivo rat retinas, ex vivo retinal explant, and primary retinal cells. Intravitreally administered fluorescent EVs were rapidly cleared from the vitreous. Retinal ganglion cells (RGCs) had maximal EV fluorescence at 14 days post administration, and microglia at 7 days. Both in vivo and in the explant model, most EVs were no deeper than the inner nuclear layer. Retinal astrocytes, microglia, and mixed neurons in vitro endocytosed EVs in a dose-dependent manner. Thus, our results indicate that intravitreal EVs are suited for the treatment of retinal diseases affecting the inner retina. Modification of the EV surface should be considered for maintaining EVs in the vitreous for prolonged delivery.

scholarly journals Spatial receptive field properties of rat retinal ganglion cells

2011 ◽  
Vol 28 (5) ◽  
pp. 403-417 ◽  
Author(s):  
WALTER F. HEINE ◽  
CHRISTOPHER L. PASSAGLIA
Keyword(s):  
Receptive Field ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Cell Types ◽  
Quantitative Information ◽  
Retinal Ganglion ◽  
X And Y Cells ◽  
Y Cells

AbstractThe rat is a popular animal model for vision research, yet there is little quantitative information about the physiological properties of the cells that provide its brain with visual input, the retinal ganglion cells. It is not clear whether rats even possess the full complement of ganglion cell types found in other mammals. Since such information is important for evaluating rodent models of visual disease and elucidating the function of homologous and heterologous cells in different animals, we recorded from rat ganglion cells in vivo and systematically measured their spatial receptive field (RF) properties using spot, annulus, and grating patterns. Most of the recorded cells bore likeness to cat X and Y cells, exhibiting brisk responses, center-surround RFs, and linear or nonlinear spatial summation. The others resembled various types of mammalian W cell, including local-edge-detector cells, suppressed-by-contrast cells, and an unusual type with an ON–OFF surround. They generally exhibited sluggish responses, larger RFs, and lower responsiveness. The peak responsivity of brisk-nonlinear (Y-type) cells was around twice that of brisk-linear (X-type) cells and several fold that of sluggish cells. The RF size of brisk-linear and brisk-nonlinear cells was indistinguishable, with average center and surround diameters of 5.6 ± 1.3 and 26.4 ± 11.3 deg, respectively. In contrast, the center diameter of recorded sluggish cells averaged 12.8 ± 7.9 deg. The homogeneous RF size of rat brisk cells is unlike that of cat X and Y cells, and its implication regarding the putative roles of these two ganglion cell types in visual signaling is discussed.

scholarly journals The tumor dormant state. Comparison of L5178Y cells used to establish dormancy with those that emerge after its termination.

1979 ◽  
Vol 149 (3) ◽  
pp. 745-757 ◽  
Author(s):  
K J Weinhold ◽  
D A Miller ◽  
E F Wheelock
Keyword(s):  
Tumor Cells ◽  
Antigen Expression ◽  
Cell Subpopulation ◽  
Effector Cells ◽  
Dormant State ◽  
Quantitative Absorption ◽  
Tumor Outgrowth ◽  
In Vivo Growth

The tumor dormant state established in L5178Y immunized and challenged mice is characterized by a prolonged period of clinical normalcy followed by rapid tumor outgrowth. The tumor cells which emerged after termination of the tumor dormant state had abnormal marker chromosomes identical to those in the L5178Y cells used in the original challenge inoculum, indicating that the emergent tumor cells were progeny of the challenge inoculum. Original and emergent L5178Y cells had equivalent in vivo growth rates, when inoculated into normal DBA/2 mice. The emergent L5178Y cells were less susceptible than original cells to in vitro lysis by tumor dormant PC. Original and emergent L5178Y cells expressed common tumor-associated target antigens for cytolytic effector cells. Both modulation and masking of these target antigens were ruled out as mechanisms for decreased susceptibility to cell-mediated cytolysis. Immunofluorescence revealed heterogeneity in tumor-associated antigen expression within both original and emergent cell populations, with a decreased intensity of staining in the emergent population. Both populations were equally susceptible to lysis by alloimmune cells, alloantiserum, and anti-Thy 1.2 serum, but emergent cells were less susceptible to lysis by serum directed against L5178Y TAA. Quantitative absorption revealed that the emergent L5178Y cells expressed eightfold less serologically detectable TAA than the original cells. These findings indicate that the host immune response developing during establishment of the tumor dormant state selects a stable tumor cell subpopulation which expresses decreased amounts of surface tumor-associated target antigens.

scholarly journals Exosome-Mediated Delivery of the Neuroprotective Peptide PACAP38 Promotes Retinal Ganglion Cell Survival and Axon Regeneration in Rats With Traumatic Optic Neuropathy

2021 ◽  
Vol 9 ◽  
Author(s):  
Tian Wang ◽  
Yiming Li ◽  
Miao Guo ◽  
Xue Dong ◽  
Mengyu Liao ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Ganglion Cell ◽  
Retinal Ganglion Cell ◽  
Optic Neuropathy ◽  
Axon Regeneration ◽  
Retinal Ganglion ◽  
Traumatic Optic Neuropathy ◽  
Fiber Layer

Traumatic optic neuropathy (TON) refers to optic nerve damage caused by trauma, leading to partial or complete loss of vision. The primary treatment options, such as hormonal therapy and surgery, have limited efficacy. Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), a functional endogenous neuroprotective peptide, has emerged as a promising therapeutic agent. In this study, we used rat retinal ganglion cell (RGC) exosomes as nanosized vesicles for the delivery of PACAP38 loaded via the exosomal anchor peptide CP05 (EXOPACAP38). EXOPACAP38 showed greater uptake efficiency in vitro and in vivo than PACAP38. The results showed that EXOPACAP38 significantly enhanced the RGC survival rate and retinal nerve fiber layer thickness in a rat TON model. Moreover, EXOPACAP38 significantly promoted axon regeneration and optic nerve function after injury. These findings indicate that EXOPACAP38 can be used as a treatment option and may have therapeutic implications for patients with TON.

Epigenetic approaches to cancer therapy

2004 ◽  
Vol 32 (6) ◽  
pp. 1095-1097 ◽  
Author(s):  
J.A. Plumb ◽  
N. Steele ◽  
P.W. Finn ◽  
R. Brown
Keyword(s):  
Dna Methylation ◽  
Cell Line ◽  
Gene Promoter ◽  
Resistant Cell ◽  
Resistant Cell Line ◽  
Tumour Suppressor Genes ◽  
Control Of Gene Expression ◽  
Hmlh1 Gene

Histone deacetylation and DNA methylation have a central role in the control of gene expression, including transcriptional repression of tumour suppressor genes. Loss of DNA mismatch repair due to methylation of the hMLH1 gene promoter results in resistance to cisplatin in vitro and in vivo. The cisplatin-resistant cell line A2780/cp70 is 8-fold more resistant to cisplatin than the non-resistant cell line, and has the hMLH1 gene methylated. Treatment with an inhibitor of DNA methyltransferase, DAC (2-deoxy-5′-azacytidine), results in a partial reversal of DNA methylation, re-expression of MLH1 (mutL homologue 1) and sensitization to cisplatin both in vitro and in vivo. PXD101 is a novel hydroxamate type histone deacetylase inhibitor that shows antitumour activity in vivo and is currently in phase I clinical evaluation. Treatment of A2780/cp70 tumour-bearing mice with DAC followed by PXD101 results in a marked increase in the number of cells that re-express MLH1. Since the clinical use of DAC may be limited by toxicity and eventual re-methylation of genes, we suggest that the combination of DAC and PXD101 could have a role in increasing the efficacy of chemotherapy in patients with tumours that lack MLH1 expression due to hMLH1 gene promoter methylation.

The development of the pattern of retinal ganglion cells in the chick retina: mechanisms that control differentiation

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5713-5724 ◽  
Author(s):  
K.L. McCabe ◽  
E.C. Gunther ◽  
T.A. Reh
Keyword(s):  
Cell Differentiation ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Receptor Activation ◽  
Peripheral Retina ◽  
Retinal Ganglion ◽  
Fgf Receptor ◽  
Chick Retina ◽  
Regular Arrays

Neurons in both vertebrate and invertebrate eyes are organized in regular arrays. Although much is known about the mechanisms involved in the formation of the regular arrays of neurons found in invertebrate eyes, much less is known about the mechanisms of formation of neuronal mosaics in the vertebrate eye. The purpose of these studies was to determine the cellular mechanisms that pattern the first neurons in vertebrate retina, the retinal ganglion cells. We have found that the ganglion cells in the chick retina develop as a patterned array that spreads from the central to peripheral retina as a wave front of differentiation. The onset of ganglion cell differentiation keeps pace with overall retinal growth; however, there is no clear cell cycle synchronization at the front of differentiation of the first ganglion cells. The differentiation of ganglion cells is not dependent on signals from previously formed ganglion cells, since isolation of the peripheral retina by as much as 400 μm from the front of ganglion cell differentiation does not prevent new ganglion cells from developing. Consistent with previous studies, blocking FGF receptor activation with a specific inhibitor to the FGFRs retards the movement of the front of ganglion cell differentiation, while application of exogenous FGF1 causes the precocious development of ganglion cells in peripheral retina. Our observations, taken together with those of previous studies, support a role for FGFs and FGF receptor activation in the initial development of retinal ganglion cells from the undifferentiated neuroepithelium peripheral to the expanding wave front of differentiation.

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