scholarly journals Oligodendrocytes support axonal transport and maintenance via exosome secretion

PLoS Biology ◽  
2020 ◽  
Vol 18 (12) ◽  
pp. e3000621
Author(s):  
Carsten Frühbeis ◽  
Wen Ping Kuo-Elsner ◽  
Christina Müller ◽  
Kerstin Barth ◽  
Leticia Peris ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Axonal Degeneration ◽  
Specific Gene ◽  
Wild Type ◽  
Neuronal Viability ◽  
Mouse Mutants ◽  
Gene Defects ◽  
Term Maintenance

Neurons extend long axons that require maintenance and are susceptible to degeneration. Long-term integrity of axons depends on intrinsic mechanisms including axonal transport and extrinsic support from adjacent glial cells. The mechanisms of support provided by myelinating oligodendrocytes to underlying axons are only partly understood. Oligodendrocytes release extracellular vesicles (EVs) with properties of exosomes, which upon delivery to neurons improve neuronal viability in vitro. Here, we show that oligodendroglial exosome secretion is impaired in 2 mouse mutants exhibiting secondary axonal degeneration due to oligodendrocyte-specific gene defects. Wild-type oligodendroglial exosomes support neurons by improving the metabolic state and promoting axonal transport in nutrient-deprived neurons. Mutant oligodendrocytes release fewer exosomes, which share a common signature of underrepresented proteins. Notably, mutant exosomes lack the ability to support nutrient-deprived neurons and to promote axonal transport. Together, these findings indicate that glia-to-neuron exosome transfer promotes neuronal long-term maintenance by facilitating axonal transport, providing a novel mechanistic link between myelin diseases and secondary loss of axonal integrity.

scholarly journals Oligodendrocytes support axonal transport and maintenance via exosome secretion

2019 ◽  
Author(s):  
Carsten Frühbeis ◽  
Wen Ping Kuo-Elsner ◽  
Christina Müller ◽  
Kerstin Barth ◽  
Leticia Peris ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Glial Cells ◽  
Axonal Degeneration ◽  
Specific Gene ◽  
Neuronal Viability ◽  
Mouse Mutants ◽  
Gene Defects ◽  
Term Maintenance

AbstractNeurons extend long axons that require maintenance and are susceptible to degeneration. Long-term integrity of axons depends on intrinsic mechanisms including axonal transport and extrinsic support from adjacent glial cells. The mechanisms of support provided by myelinating oligodendrocytes to underlying axons are only partly understood. Oligodendrocytes release extracellular vesicles (EVs) with properties of exosomes, which upon delivery to neurons improve neuronal viability in vitro. Here, we show that oligodendroglial exosome secretion is impaired in two mouse mutants exhibiting secondary axonal degeneration due to oligodendrocyte-specific gene defects. Wildtype oligodendroglial exosomes support neurons by improving the metabolic state and promoting axonal transport in nutrient deprived neurons. Mutant oligodendrocytes release less exosomes that share a common signature of underrepresented proteins. Notably, mutant exosomes lack the ability to support nutrient deprived neurons and to promote axonal transport. Together, these findings indicate that glia to neuron exosome transfer promotes neuronal long-term maintenance by facilitating axonal transport, providing a novel mechanistic link between myelin diseases and secondary loss of axonal integrity.

scholarly journals Glucose Transporter 8 (GLUT8) Regulates Enterocyte Fructose Transport and Global Mammalian Fructose Utilization

Endocrinology ◽  
2012 ◽  
Vol 153 (9) ◽  
pp. 4181-4191 ◽  
Author(s):  
Brian J. DeBosch ◽  
Maggie Chi ◽  
Kelle H. Moley
Keyword(s):  
Glucose Transporter ◽  
Serum Insulin ◽  
Density Lipoprotein ◽  
Wild Type ◽  
In Vivo Models ◽  
The Metabolic Syndrome ◽  
High Fructose

Enterocyte fructose absorption is a tightly regulated process that precedes the deleterious effects of excess dietary fructose in mammals. Glucose transporter (GLUT)8 is a glucose/fructose transporter previously shown to be expressed in murine intestine. The in vivo function of GLUT8, however, remains unclear. Here, we demonstrate enhanced fructose-induced fructose transport in both in vitro and in vivo models of enterocyte GLUT8 deficiency. Fructose exposure stimulated [14C]-fructose uptake and decreased GLUT8 protein abundance in Caco2 colonocytes, whereas direct short hairpin RNA-mediated GLUT8 knockdown also stimulated fructose uptake. To assess GLUT8 function in vivo, we generated GLUT8-deficient (GLUT8KO) mice. GLUT8KO mice exhibited significantly greater jejunal fructose uptake at baseline and after high-fructose diet (HFrD) feeding vs. wild-type mice. Strikingly, long-term HFrD feeding in GLUT8KO mice exacerbated fructose-induced increases in blood pressure, serum insulin, low-density lipoprotein and total cholesterol vs. wild-type controls. Enhanced fructose uptake paralleled with increased abundance of the fructose and glucose transporter, GLUT12, in HFrD-fed GLUT8KO mouse enterocytes and in Caco2 cultures exposed to high-fructose medium. We conclude that GLUT8 regulates enterocyte fructose transport by regulating GLUT12, and that disrupted GLUT8 function has deleterious long-term metabolic sequelae. GLUT8 may thus represent a modifiable target in the prevention and treatment of malnutrition or the metabolic syndrome.

scholarly journals The Carbamate, Physostigmine does not Impair Axonal Transport in Rat Cortical Neurons

2021 ◽  
Vol 16 ◽  
pp. 263310552110202
Author(s):  
Sean X Naughton ◽  
Wayne D Beck ◽  
Zhe Wei ◽  
Guangyu Wu ◽  
Peter W Baas ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Cortical Neurons ◽  
Acetylcholinesterase Inhibitors ◽  
Neurological Deficits ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Rat Cortical Neurons ◽  
Toxicological Mechanism

Among the various chemicals that are commonly used as pesticides, organophosphates (OPs), and to a lesser extent, carbamates, are most frequently associated with adverse long-term neurological consequences. OPs and the carbamate, pyridostigmine, used as a prophylactic drug against potential nerve agent attacks, have also been implicated in Gulf War Illness (GWI), which is often characterized by chronic neurological symptoms. While most OP- and carbamate-based pesticides, and pyridostigmine are relatively potent acetylcholinesterase inhibitors (AChEIs), this toxicological mechanism is inadequate to explain their long-term health effects, especially when no signs of acute cholinergic toxicity are exhibited. Our previous work suggests that a potential mechanism of the long-term neurological deficits associated with OPs is impairment of axonal transport (AXT); however, we had not previously evaluated carbamates for this effect. Here we thus evaluated the carbamate, physostigmine (PHY), a highly potent AChEI, on AXT using an in vitro neuronal live imaging assay that we have previously found to be very sensitive to OP-related deficits in AXT. We first evaluated the OP, diisopropylfluorophosphate (DFP) (concentration range 0.001-10.0 µM) as a reference compound that we found previously to impair AXT and subsequently evaluated PHY (concentration range 0.01-100 nM). As expected, DFP impaired AXT in a concentration-dependent manner, replicating our previously published results. In contrast, none of the concentrations of PHY (including concentrations well above the threshold for impairing AChE) impaired AXT. These data suggest that the long-term neurological deficits associated with some carbamates are not likely due to acute impairments of AXT.

Long-term maintenance of reaggregated hypothalamic cultures developed from embryonic rat hypothalamus: prostaglandin release during synaptogenesis in vitro

1978 ◽  
Vol 34 (1) ◽  
pp. 159-171
Author(s):  
A. Gyevai ◽  
P.J. Chapple ◽  
W.H. Douglas
Keyword(s):  
Adult Animal ◽  
Morphological Differentiation ◽  
Adult Rat ◽  
Monolayer Cultures ◽  
Prostaglandin Release ◽  
Pge2 Concentration ◽  
The Media ◽  
Term Maintenance

Hypothalamic aggregate cultures were developed from hypothalami taken from rat embryos at 17–19 days gestation. The aggregate cultures exhibited a prominent morphological differentiation during 3–4 weeks in culture. The fine structure of the synapses formed in the aggregates resembled synapses in tha adult animal. During synaptogenesis the aggregates spontaneously release prostaglandin E2 (PGE2). The amount of PGE2 released in the media was reversed upon the morphological differentiation of the hypothalamic cultures. Media containing a higher PGE2 concentration increased the extracellular prolactin accumulation in monolayer cultures developed from adult rat hypophysis.

scholarly journals Gene transfer into hematopoietic stem cells: long-term maintenance of in vitro activated progenitors without marrow ablation.

1994 ◽  
Vol 91 (1) ◽  
pp. 350-354 ◽  
Author(s):  
D. Bienzle ◽  
A. C. Abrams-Ogg ◽  
S. A. Kruth ◽  
J. Ackland-Snow ◽  
R. F. Carter ◽  
...  
Keyword(s):  
Stem Cells ◽  
Gene Transfer ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Stem ◽  
Marrow Ablation ◽  
Term Maintenance

scholarly journals Requirement of the C-terminal proline residue for stability of the Ca2+-activated photoprotein aequorin

1993 ◽  
Vol 293 (1) ◽  
pp. 181-185 ◽  
Author(s):  
N J Watkins ◽  
A K Campbell
Keyword(s):  
Light Emission ◽  
Specific Activity ◽  
In Vitro Transcription ◽  
Wild Type ◽  
Proline Residue ◽  
Long Term Stability ◽  
Recombinant Aequorin

cDNA coding for the Ca(2+)-activated photoprotein aequorin from the jellyfish Aequorea victoria has been engineered to investigate the role of the C-terminal proline residue in bioluminescence. Recombinant aequorin proteins were synthesized by PCR followed by in vitro transcription/translation, and characterized by specific activity, stability, and affinity for coelenterazine. The C-terminal proline residue of aequorin was shown to be essential for the long-term stability of the bound coelenterazine. Aequorin minus proline had only 1% of the specific activity of the wild-type after 2 h, and was virtually inactive after 18 h. The instability of this variant was further demonstrated by re-activating with a coelenterazine analogue (epsilon-coelenterazine), where maximum reactivation was reached in 15 min, and the luminescent activity was almost completely abolished within 3 h. Replacement of the C-terminal proline residue with histidine or glutamic acid decreased the specific activity to 10 and 19% of that of the wild-type respectively. However these variants were also unstable, having t1/2 values of 2.4 h and 2.3 h respectively. Enhancement of the Ca(2+)-independent light emission when proline was replaced by histidine confirmed the stabilizing role of the C-terminal proline. No significant effect of removal of the C-terminal proline was detected on the affinity for coelenterazine.

scholarly journals Human Cytomegalovirus Resistance to Deoxyribosylindole Nucleosides Maps to a Transversion Mutation in the Terminase Subunit-Encoding GeneUL89

2014 ◽  
Vol 59 (1) ◽  
pp. 226-232 ◽  
Author(s):  
Brian G. Gentry ◽  
Quang Phan ◽  
Ellie D. Hall ◽  
Julie M. Breitenbach ◽  
Katherine Z. Borysko ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Structural Similarity ◽  
Open Reading Frames ◽  
Wild Type Virus ◽  
Wild Type ◽  
Term Administration ◽  
Transversion Mutation ◽  
Exon 1

ABSTRACTHuman cytomegalovirus (HCMV) infection can cause severe illnesses, including encephalopathy and mental retardation, in immunocompromised and immunologically immature patients. Current pharmacotherapies for treating systemic HCMV infections include ganciclovir, cidofovir, and foscarnet. However, long-term administration of these agents can result in serious adverse effects (myelosuppression and/or nephrotoxicity) and the development of viral strains with reduced susceptibility to drugs. The deoxyribosylindole (indole) nucleosides demonstrate a 20-fold greater activityin vitro(the drug concentration at which 50% of the number of plaques was reduced with the presence of drug compared to the number in the absence of drug [EC50] = 0.34 μM) than ganciclovir (EC50= 7.4 μM) without any observed increase in cytotoxicity. Based on structural similarity to the benzimidazole nucleosides, we hypothesize that the indole nucleosides target the HCMV terminase, an enzyme responsible for packaging viral DNA into capsids and cleaving the DNA into genome-length units. To test this hypothesis, an indole nucleoside-resistant HCMV strain was isolated, the open reading frames of the genes that encode the viral terminase were sequenced, and a G766C mutation in exon 1 ofUL89was identified; this mutation resulted in an E256Q change in the amino acid sequence of the corresponding protein. An HCMV wild-type strain, engineered with this mutation to confirm resistance, demonstrated an 18-fold decrease in susceptibility to the indole nucleosides (EC50= 3.1 ± 0.7 μM) compared to that of wild-type virus (EC50= 0.17 ± 0.04 μM). Interestingly, this mutation did not confer resistance to the benzimidazole nucleosides (EC50for wild-type HCMV = 0.25 ± 0.04 μM, EC50for HCMV pUL89 E256Q = 0.23 ± 0.04 μM). We conclude, therefore, that the G766C mutation that results in the E256Q substitution is unique for indole nucleoside resistance and distinct from previously discovered substitutions that confer both indole and benzimidazole nucleoside resistance (D344E and A355T).

A novel cultivation technique for long-term maintenance of bloodstream form trypanosomes in vitro

1995 ◽  
Vol 70 (1-2) ◽  
pp. 157-166 ◽  
Author(s):  
Friedemann Hesse ◽  
Paul M. Selzer ◽  
Kerstin Mühlstädt ◽  
Michael Duszenko
Keyword(s):  
Bloodstream Form ◽  
Cultivation Technique ◽  
Term Maintenance

Pancreatic small cells: Analysis of quiescence, long-term maintenance and insulin expression in vitro

2007 ◽  
Vol 313 (5) ◽  
pp. 931-942 ◽  
Author(s):  
M. Petropavlovskaia ◽  
C.A. Bodnar ◽  
L.A. Behie ◽  
L. Rosenberg
Keyword(s):  
Small Cells ◽  
Insulin Expression ◽  
Term Maintenance
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