A target-derived chemoattractant controls the development of the corticopontine projection by a novel mechanism of axon targeting

Here, we review our studies in rats of target recognition by developing cortical axons focusing on their innervation of the basilar pons, a major hindbrain target. The corticopontine projection develops by a ‘delayed interstitial budding’ of collaterals from layer 5 corticospinal axons, rather than by a direct ingrowth of primary axons or by bifurcation of the growth cone. Branches form de novo from the axon cylinder in the pathway overlying the basilar pons and extend directly into it. Cocultures of cortex and basilar pons in 3-dimensional collagen matrices show that a diffusible chemotropic signal released by the basilar pons directs the growth of collateral branches from layer 5 axons in a target and neuron specific manner. ‘Delayed’ co-cultures suggest that a diffusible, pontine-derived signal also initiates the selective branching of layer 5 axons. In vivo experiments support this chemotropic mechanism. First, corticospinal axons form collateral branches at novel locations directly over ectopic aggregations of basilar pontine neurons induced by X-irradiation; no branches form at positions that would normally overlie the appropriate region of basilar pons which is absent because of the X-irradiation. Thus, the basilar pons, rather than local cues in the axon pathway, appears to control the location of corticospinal axon branching. Second, in a series of experiments in which different subsets of corticospinal axons are prevented from innervating the basilar pons, remaining corticospinal axons extend collaterals in a directed manner to regions of the basilar pons deprived of cortical input, a behavior consistent with a response to a diffusible chemoattractant emanating from these regions. In conclusion, our findings suggest that a diffusible, target-derived chemotropic molecule(s) underlies target recognition in this developing system by initiating the formation and directing the growth of pontine collateral branches of primary layer 5 corticospinal axons.

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Circular RNA UBE2Q2 promotes malignant progression of gastric cancer by regulating signal transducer and activator of transcription 3-mediated autophagy and glycolysis

Cell Death and Disease ◽

10.1038/s41419-021-04216-3 ◽

2021 ◽

Vol 12 (10) ◽

Author(s):

Jing Yang ◽

Xing Zhang ◽

Jiacheng Cao ◽

Penghui Xu ◽

Zetian Chen ◽

...

Keyword(s):

Gastric Cancer ◽

Rna Binding ◽

Synergistic Effects ◽

Circular Rna ◽

Circular Rnas ◽

In Vivo Experiments ◽

Series Of Experiments ◽

Transcription 3

AbstractGastric cancer remains the third leading cause of cancer-related mortality worldwide. Emerging evidence has shown that circular RNAs (circRNAs) play a critical regulatory role in the occurrence and development of various cancers through sponging miRNAs or acting as RNA-binding protein (RBP) sponges. We found that circUBE2Q2 was significantly upregulated in GC tissues and cell lines. Knockdown of circUBE2Q2 inhibited proliferation, migration, invasion, and glycolysis, and increased autophagy in vitro. In addition, knockdown of circUBE2Q2 inhibited GC tumorigenicity and metastasis potential in vivo. A series of experiments were performed to confirm that circUBE2Q2 regulates GC progression via the circUBE2Q2-miR-370-3p-STAT3 axis and promotes tumor metastasis through exosomal communication. Further in vivo experiments confirmed that, combination treatment of circUBE2Q2 knocking down and STAT3 inhibitor has synergistic effects on the gastric cancer growth inhibition, which provides a possibility to enhance the sensitivity of targeted drugs to gastric cancer through targeting circUBE2Q2. Our findings revealed that circUBE2Q2 may serve as a new proliferation-promoting factor and prognostic marker in gastric cancer.

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Tissue Engineering in Cartilage Repair: In Vitro and In Vivo Experiments on Cell-Seeded Collagen Matrices

Osteoarthritis ◽

10.1007/978-3-642-87752-0_10 ◽

2000 ◽

pp. 111-120

Author(s):

S. Nehrer ◽

M. Spector

Keyword(s):

Tissue Engineering ◽

Cartilage Repair ◽

Collagen Matrices ◽

In Vivo Experiments

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A Strategy for Combinatorial Cavity Design in De Novo Proteins

Life ◽

10.3390/life10020009 ◽

2020 ◽

Vol 10 (2) ◽

pp. 9 ◽

Cited By ~ 3

Author(s):

Christina Karas ◽

Michael Hecht

Keyword(s):

De Novo ◽

Protein S ◽

Dimensional Structure ◽

3 Dimensional ◽

Functional Sites ◽

Helical Proteins ◽

Living Organisms ◽

Protein Sequence Space

Protein sequence space is vast; nature uses only an infinitesimal fraction of possible sequences to sustain life. Are there solutions to biological problems other than those provided by nature? Can we create artificial proteins that sustain life? To investigate these questions, we have created combinatorial collections, or libraries, of novel sequences with no homology to those found in living organisms. Previously designed libraries contained numerous functional proteins. However, they often formed dynamic, rather than well-ordered structures, which complicated structural and mechanistic characterization. To address this challenge, we describe the development of new libraries based on the de novo protein S-824, a 4-helix bundle with a very stable 3-dimensional structure. Distinct from previous libraries, we targeted variability to a specific region of the protein, seeking to create potential functional sites. By characterizing variant proteins from this library, we demonstrate that the S-824 scaffold tolerates diverse amino acid substitutions in a putative cavity, including buried polar residues suitable for catalysis. We designed and created a DNA library encoding 1.7 × 106 unique protein sequences. This new library of stable de novo α-helical proteins is well suited for screens and selections for a range of functional activities in vitro and in vivo.

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Temporal covariance of pre- and postsynaptic activity regulates functional connectivity in the visual cortex

Journal of Neurophysiology ◽

10.1152/jn.1994.71.4.1403 ◽

1994 ◽

Vol 71 (4) ◽

pp. 1403-1421 ◽

Cited By ~ 55

Author(s):

Y. Fregnac ◽

J. P. Burke ◽

D. Smith ◽

M. J. Friedlander

Keyword(s):

Visual Cortex ◽

Brain Slices ◽

Low Frequency ◽

Stimulation Site ◽

Independent Manner ◽

In Vivo Experiments ◽

Postsynaptic Activity ◽

Series Of Experiments

1. It has been suggested from mathematical models and in vivo experiments in the visual cortex that periods of temporal covariance of pre- and postsynaptic activity can lead to a potentiation or depression of synaptic efficacy. We directly tested this hypothesis in vitro in the guinea pig and cat visual cortex. 2. Intracellular recordings were made in brain slices from 63 neurons in layers 2-4 in bicuculline-free artificial cerebrospinal fluid. Twenty-nine cells (n = 25 from pigmented guinea pigs and 4 from cats) were taken through a complete series of control and test protocols to evaluate the covariance hypothesis. Some (n = 7) cells that were taken through the complete experimental protocols were also filled intracellularly with biocytin. Compound postsynaptic potentials (PSPs) were evoked by low-frequency (0.2-1.0 Hz), weak (20% of threshold intensity) stimulation of the cortical white matter and/or intracortical sites in layers 2-3. 3. In one series of experiments we paired PSPs with imposed coincident depolarizing (S+) or hyperpolarizing (S-) pulses (mean +/- 2.8 nA for 50-80 ms) of the postsynaptic neuron (n = 54 PSPs; > 1 pairing protocol was often run on an individual cell). Controls consisted of analyzing the same number of S+ or S- pairings but with long temporal delays [called fixed delay pairings (FDPs)] between the test pathway stimulation and the onset of the intracellular current pulse (120 ms) and pseudopairings (PP) consisting of evoked PSPs and delivery of intracellular current injection pulses in a phase-independent manner. Twenty-one of 54 PSPs subjected to pairing were significantly modified by the protocol. The S+ protocol significantly (P < 0.05, Kolmogorov-Smirnov test) increased the peak amplitudes of 8 of 22 PSPs (+20 to +55%); the S- protocol significantly decreased the peak amplitudes of 13 of 32 PSPs (-15 to -88%), whereas the FDP and PP protocols generally did not cause significant changes in the PSPs (0% and 4%, respectively). Significant changes in PSPs persisted in most cases for 10-20 min. 4. Another series of experiments consisted of evaluating for the same cell the effects of evoking a PSP from one stimulation site without concomitant postsynaptic activation and alternately evoking a PSP from the other stimulation site with S+ or S- pairing (n = 25 PSPs). Only the paired pathway showed the predicted effects on the PSP (S+ pairing causing an increase in peak PSP amplitude and S- pairing causing a decrease in peak PSP amplitude).(ABSTRACT TRUNCATED AT 400 WORDS)

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IRRADIATION OF DIPHOSPHOPYRIDINE NUCLEOTIDE IN DILUTE AQUEOUS SOLUTIONS

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o60-157 ◽

1960 ◽

Vol 38 (11) ◽

pp. 1255-1263 ◽

Cited By ~ 1

Author(s):

D. K. Myers

Keyword(s):

Absorption Spectrum ◽

Aqueous Solutions ◽

Ultraviolet Absorption ◽

Ultraviolet Absorption Spectrum ◽

Ph Values ◽

In Vivo Experiments ◽

X Irradiation ◽

Dilute Aqueous Solutions

In extension of previous in vivo experiments, the effects of X irradiation on DPN were studied in vitro. No correlation between the effects on the ultraviolet absorption spectrum and on the coenzyme function of DPN was evident after irradiation at different pH values. However, the loss of coenzyme function could be correlated with the destruction of ribose and of riboside linkages. Catalase did not provide greater protection than did other proteins. It was concluded that the observed loss of DPN from irradiated cells is not due to the radiosensitivity of the DPN molecule itself.

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Chitosan-Calcium-Simvastatin Scaffold as an Inductive Cell-Free Platform

Journal of Dental Research ◽

10.1177/00220345211024207 ◽

2021 ◽

pp. 002203452110242

Author(s):

D.G. Soares ◽

E.A.F. Bordini ◽

E.S. Bronze-Uhle ◽

F.B. Cassiano ◽

I.S.P. Silva ◽

...

Keyword(s):

3D Culture ◽

3 Dimensional ◽

Matrix Deposition ◽

Odontoblastic Differentiation ◽

In Vivo Experiments ◽

Regenerative Dentistry ◽

Pulp Cells ◽

Dentin Sialoprotein ◽

Bioactive Potential

The development of biomaterials based on the combination of biopolymers with bioactive compounds to develop delivery systems capable of modulating dentin regeneration mediated by resident cells is the goal of current biology-based strategies for regenerative dentistry. In this article, the bioactive potential of a simvastatin (SV)–releasing chitosan-calcium-hydroxide (CH-Ca) scaffold was assessed. After the incorporation of SV into CH-Ca, characterization of the scaffold was performed. Dental pulp cells (DPCs) were seeded onto scaffolds for the assessment of cytocompatibility, and odontoblastic differentiation was evaluated in a microenvironment surrounded by dentin. Thereafter, the cell-free scaffold was adapted to dentin discs positioned in artificial pulp chambers in direct contact with a 3-dimensional (3D) culture of DPCs, and the system was sealed to simulate internal pressure at 20 cm/H2O. In vivo experiments with cell-free scaffolds were performed in rats’ calvaria defects. Fourier-transform infrared spectroscopy spectra proved incorporation of Ca and SV into the scaffold structure. Ca and SV were released upon immersion in a neutral environment. Viable DPCs were able to spread and proliferate on the scaffold over 14 d. Odontoblastic differentiation occurred in the DPC/scaffold constructs in contact with dentin, in which SV supplementation promoted odontoblastic marker overexpression and enhanced mineralized matrix deposition. The chemoattractant potential of the CH-Ca scaffold was improved by SV, with numerous viable and dentin sialoprotein–positive cells from the 3D culture being observed on its surface. Cells at 3D culture featured increased gene expression of odontoblastic markers in contact with the SV-enriched CH-Ca scaffold. CH-Ca-SV led to intense mineralization in vivo, presenting mineralization foci inside its structure. In conclusion, the CH-Ca-SV scaffold induces differentiation of DPCs into a highly mineralizing phenotype in the presence of dentin, creating a microenvironment capable of attracting pulp cells to its surface and inducing the overexpression of odontoblastic markers in a cell-homing strategy.

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