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VEGF increases serine phosphorylation of AMPA receptor GluA2 subunit in astrocytes via activation of Flk1 receptor. (a-d) Total
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Astrocytic calcium signaling plays pivotal roles in the maintenance of neural functions and neurovascular coupling in the brain. Vascular endothelial growth factor (VEGF), an original biological substance of vessels, regulates the movement of calcium and potassium ions across neuronal membrane. In this study, we investigated whether and how VEGF re...
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... | RESULTS 3.1 | VEGF increases serine phosphorylation of AMPA receptor GluA2 subunit in astrocytes via activation of Flk1 receptor Figure 1b). Interestingly, we also found that VEGF treatment significantly increased the serine phosphorylation of AMPA receptor subunit GluA2, but not GluA1 in astrocytes, while it had no effect on total GluA1 and GluA2 protein levels (Figure 1c,d). ...
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... | RESULTS 3.1 | VEGF increases serine phosphorylation of AMPA receptor GluA2 subunit in astrocytes via activation of Flk1 receptor Figure 1b). Interestingly, we also found that VEGF treatment significantly increased the serine phosphorylation of AMPA receptor subunit GluA2, but not GluA1 in astrocytes, while it had no effect on total GluA1 and GluA2 protein levels (Figure 1c,d). VEGF treatment increased the serine phosphorylated GluA2 levels to 4.32 ± 0.71 times at 1 min, 3.23 ± 0.40 at 20 min and turned to baseline at 30 min, compared to vehicle treatment (Figure 1d). ...
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... we also found that VEGF treatment significantly increased the serine phosphorylation of AMPA receptor subunit GluA2, but not GluA1 in astrocytes, while it had no effect on total GluA1 and GluA2 protein levels (Figure 1c,d). VEGF treatment increased the serine phosphorylated GluA2 levels to 4.32 ± 0.71 times at 1 min, 3.23 ± 0.40 at 20 min and turned to baseline at 30 min, compared to vehicle treatment (Figure 1d). Moreover, VEGF (20 min, 50 ng/mL)-increased GluA2 serine phosphorylation was completely blocked by co-incubation with SU1498, an antagonist for VEGF Flk1 receptor, and the antagonist alone had no effect on the GluA2 serine phosphorylation (Figure 1e,f). ...
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... treatment increased the serine phosphorylated GluA2 levels to 4.32 ± 0.71 times at 1 min, 3.23 ± 0.40 at 20 min and turned to baseline at 30 min, compared to vehicle treatment (Figure 1d). Moreover, VEGF (20 min, 50 ng/mL)-increased GluA2 serine phosphorylation was completely blocked by co-incubation with SU1498, an antagonist for VEGF Flk1 receptor, and the antagonist alone had no effect on the GluA2 serine phosphorylation (Figure 1e,f). ...
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... | RESULTS 3.1 | VEGF increases serine phosphorylation of AMPA receptor GluA2 subunit in astrocytes via activation of Flk1 receptor Figure 1b). Interestingly, we also found that VEGF treatment signifi- cantly increased the serine phosphorylation of AMPA receptor subu- nit GluA2, but not GluA1 in astrocytes, while it had no effect on total GluA1 and GluA2 protein levels (Figure 1c,d). ...
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... | RESULTS 3.1 | VEGF increases serine phosphorylation of AMPA receptor GluA2 subunit in astrocytes via activation of Flk1 receptor Figure 1b). Interestingly, we also found that VEGF treatment signifi- cantly increased the serine phosphorylation of AMPA receptor subu- nit GluA2, but not GluA1 in astrocytes, while it had no effect on total GluA1 and GluA2 protein levels (Figure 1c,d). VEGF treatment increased the serine phosphorylated GluA2 levels to 4.32 ± 0.71 times at 1 min, 3.23 ± 0.40 at 20 min and turned to baseline at 30 min, compared to vehicle treatment (Figure 1d). ...
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... we also found that VEGF treatment signifi- cantly increased the serine phosphorylation of AMPA receptor subu- nit GluA2, but not GluA1 in astrocytes, while it had no effect on total GluA1 and GluA2 protein levels (Figure 1c,d). VEGF treatment increased the serine phosphorylated GluA2 levels to 4.32 ± 0.71 times at 1 min, 3.23 ± 0.40 at 20 min and turned to baseline at 30 min, compared to vehicle treatment (Figure 1d). Moreover, VEGF (20 min, 50 ng/mL)-increased GluA2 serine phosphorylation was completely blocked by co-incubation with SU1498, an antagonist for VEGF Flk1 receptor, and the antagonist alone had no effect on the GluA2 serine phosphorylation (Figure 1e,f). ...
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... treatment increased the serine phosphorylated GluA2 levels to 4.32 ± 0.71 times at 1 min, 3.23 ± 0.40 at 20 min and turned to baseline at 30 min, compared to vehicle treatment (Figure 1d). Moreover, VEGF (20 min, 50 ng/mL)-increased GluA2 serine phosphorylation was completely blocked by co-incubation with SU1498, an antagonist for VEGF Flk1 receptor, and the antagonist alone had no effect on the GluA2 serine phosphorylation (Figure 1e,f). ...
Citations
... Previous research has indicated that PKC-α plays a crucial role in regulating GluA2 phosphorylation (Kou et al., 2019). To investigate the mechanism by which ADSC-EVs regulate GluA2 phosphorylation, we activated PKC-α with PKC agonist TPA (100 ng/mL, 1 hour) in R28 cells (Figure 5A and B). ...
Adipose mesenchymal stem cells (ADSCs) have protective effects against glutamate-induced excitotoxicity, but ADSCs are limited in use for treatment of optic nerve injury. Studies have shown that the extracellular vesicles (EVs) secreted by ADSCs (ADSC-EVs) not only have the function of ADSCs, but also have unique advantages including non-immunogenicity, low probability of abnormal growth, and easy access to target cells. In the present study, we showed that intravitreal injection of ADSC-EVs substantially reduced glutamate-induced damage to retinal morphology and electroretinography. In addition, R28 cell pretreatment with ADSC-EVs before injury inhibited glutamate-induced overload of intracellular calcium, downregulation of α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor (AMPAR) subunit GluA2, and phosphorylation of GluA2 and protein kinase C alpha in vitro. A protein kinase C alpha agonist, 12-O-tetradecanoylphorbol 13-acetate, inhibited the neuroprotective effects of ADSC-EVs on glutamate-induced R28 cells. These findings suggest that ADSC-EVs ameliorate glutamate-induced excitotoxicity in the retina through inhibiting protein kinase C alpha activation.
... Cortical astrocytes were obtained from 1 day of newborn Sprague Dawley rats (Kou et al., 2019). The cerebral cortex was dissected free of hippocampus and striatum, minced into small cubes of 1 mm 3 after removal of meninges and blood vessels. ...
Reactive astrocytes can be transformed into new neurons. Vascular endothelial growth factor (VEGF) promotes the transformation of reactive astrocytes into neurons in ischemic brain. Therefore, in this study, the molecular mechanism of VEGF's effect on ischemia/hypoxia-induced astrocyte to neuron transformation was investigated in the models of rat middle cerebral artery occlusion (MCAO) and in astrocyte culture with oxygen and glucose deprivation (OGD). We found that VEGF enhanced ischemia-induced Pax6, a neurogenic fate determinant, expression and Erk phosphorylation in reactive astrocytes and reduced infarct volume of rat brain at 3 days after MCAO, which effects could be blocked by administration of U0126, a MAPK/Erk inhibitor. In cultured astrocytes, VEGF also enhanced OGD-induced Erk phosphorylation and Pax6 expression, which was blocked by U0126, but not wortmannin, a PI3K/Akt inhibitor, or SB203580, a MAPK/p38 inhibitor, suggesting VEGF enhanced Pax6 expression via activation of MAPK/Erk pathway. OGD induced the increase of miR365 and VEGF inhibited the increase of OGD-induced miR365 expression. However, miR365 agonists blocked VEGF-enhanced Pax6 expression in hypoxic astrocytes, but did not block VEGF-enhanced Erk phosphorylation. We further found that VEGF promoted OGD-induced astrocyte-converted to neuron. Interestingly, both U0126 and Pax6 RNAi significantly reduced enhancement of VEGF on astrocytes-to-neurons transformation, as indicated Dcx and MAP2 immunopositive signals in reactive astrocytes. Moreover, those transformed neurons become mature and functional. We concluded that VEGF enhanced astrocytic neurogenesis via the MAPK/Erk-miR-365-Pax6 signal axis. The results also indicated that astrocytes play important roles in the reconstruction of neurovascular units in brain after stroke.
... In mammals, the VEGF family is composed of five factors: VEGF-A, VEGF-B, VEGF-C, VEGF-D, and the placental growth factor (PlGF). The VEGF family has been implicated in numerous functions involving angiogenesis, lymphangiogenesis, development of the nervous system and its vascularization, neurogenesis, synaptic plasticity, neuronal electrophysiological properties, neurotransmission, neuronal survival, and neuroregeneration (Ruiz de Almodovar et al., 2009;Lladó et al., 2013;Chi et al., 2019;Kou et al., 2019;Latzer et al., 2019). They have also been considered factors with a promising therapeutic role in neurological diseases (Lange et al., 2016). ...
Vascular endothelial growth factor (VEGF) was discovered by its angiogenic activity. However, during evolution, it appeared earlier as a neurotrophic factor required for the development of the nervous system in invertebrates lacking a circulatory system. We aimed at reviewing recent evidence indicating that VEGF has neuroprotective effects in neurons exposed to a variety of insults. Of particular interest is the link established between VEGF and motoneurons, especially after the design of the VEGFδ/δ mutant mice. These mice are characterized by low levels of VEGF and develop muscle weakness and motoneuron degeneration resembling amyotrophic lateral sclerosis. The administration of VEGF through several routes to animal models of amyotrophic lateral sclerosis delays motor impairment and motoneuron degeneration and increases life expectancy. There are new recent advances in the role of VEGF in the physiology of motoneurons. Our experimental aims use the extraocular (abducens) motoneurons lesioned by axotomy as a model for studying VEGF actions. Axotomized abducens motoneurons exhibit severe alterations in their discharge activity and a loss of synaptic boutons. The exogenous administration of VEGF to axotomized abducens motoneurons, either from the transected nerve or intraventricularly, fully restores the synaptic and discharge properties of abducens motoneurons, despite being axotomized. In addition, when an anti-VEGF neutralizing antibody is delivered from the muscle to intact, uninjured abducens motoneurons, these cells display alterations in their discharge pattern and a loss of synaptic boutons that resemble the state of axotomy. All these data indicate that VEGF is an essential neurotrophic factor for motoneurons.
... In addition to BDNF, other important neurotrophic factors for promoting neuroplasticity include nerve growth factor (NGF), which plays a role in the survival, growth, and differentiation of peripheral and central neurons (Hall et al., 2018), glial cell line-derived neurotrophic factor (GDNF), also known for its role in neuronal survival in the central and peripheral nervous system and promotes recovery of damaged axons at the neuromuscular junction (Cortés et al., 2017). Vascular endothelial growth factor (VEGF) promotes the growth of blood vasculature and can therefore increase neurovascular coupling (Kou et al., 2019) and finally, insulin-like growth factor 1 (IGF-1) promotes anabolic growth in nearly all bodily tissues (Wrigley et al., 2017). BDNF in particular is known to acutely enhance glutamatergic and reduce gamma aminobutyric acid (GABA) ergic synaptic transmission, thereby altering the excitation/ inhibition balance in the brain by increasing the concentration of glutamate and reducing GABA concentrations (Gottmann et al., 2009;Park and Poo, 2013). ...
Transcranial magnetic stimulation studies have demonstrated increased cortical facilitation and reduced inhibition following aerobic exercise, even when examining motor regions separate to the exercised muscle group. These changes in brain physiology following exercise may create favorable conditions for adaptive plasticity and motor learning. One candidate mechanism behind these benefits is the increase in brain-derived neurotropic factor (BDNF) observed following exercise, which can be quantified from a venous blood draw. The aim of this study was to investigate changes in motor cortex excitability and inhibition of the upper limb, and circulating BDNF, following high-intensity interval training (HIIT) on a stationary bicycle. Nineteen sedentary adults participated in a randomized crossover design study involving a single bout of high-intensity interval cycling for 20 min or seated rest. Venous blood samples were collected, and transcranial magnetic stimulation (TMS) was used to stimulate the extensor carpi radialis (ECR), where motor evoked potentials (MEP) were recorded pre- and post-condition. Following exercise, there was a significant increase (29.1%, p < 0.001) in corticospinal excitability measured at 120% of resting motor threshold (RMT) and a reduction in short-interval cortical inhibition (SICI quantified as 86.2% increase in the SICI ratio, p = 0.002). There was a non-significant (p = 0.125) 23.6% increase in BDNF levels. Collectively, these results reflect a net reduction in gamma aminobutyric acid (GABA)ergic synaptic transmission and increased glutamatergic facilitation, resulting in increased corticospinal excitability. This study supports the notion that acute high-intensity exercise provides a potent stimulus for inducing cortical neuroplasticity, which may support enhanced motor learning.
... However, quisqualate is not an iGluR-specific agonist and can activate metabotropic glutamate receptor I (mGluR I), which may have contributed to the mixed findings that QA-evoked Ca 2+ responses have an internal Ca 2+ store component [114,115,122]. Application of more specific agonists, such as AMPA, confirmed the presence of functional AMPARs on cultured hippocampal, cortical, and cerebellar astrocytes [122,123] as well as astrocytes in isolated optic nerve [124]. Third, astrocytes were cultured from different brain regions including the cortex, cerebellum, and hippocampus in these studies. ...
Astrocytes are complex glial cells that play many essential roles in the brain, including the fine-tuning of synaptic activity and blood flow. These roles are linked to fluctuations in intracellular Ca2+ within astrocytes. Recent advances in imaging techniques have identified localized Ca2+ transients within the fine processes of the astrocytic structure, which we term microdomain Ca2+ events. These Ca2+ transients are very diverse and occur under different conditions, including in the presence or absence of surrounding circuit activity. This complexity suggests that different signalling mechanisms mediate microdomain events which may then encode specific astrocyte functions from the modulation of synapses up to brain circuits and behaviour. Several recent studies have shown that a subset of astrocyte microdomain Ca2+ events occur rapidly following local neuronal circuit activity. In this review, we consider the physiological relevance of microdomain astrocyte Ca2+ signalling within brain circuits and outline possible pathways of extracellular Ca2+ influx through ionotropic receptors and other Ca2+ ion channels, which may contribute to astrocyte microdomain events with potentially fast dynamics.
... In addition, VEGF enhances the migration of oligodendrocyte precursor cells and stimulates the expression of trophic factors by glial cells [105]. Additionally, it reduces glutamate-induced calcium influx in astrocytes via AMPA receptor regulation [108]. In this sense, several VEGF family components are increased by glutamate excitotoxicity [109,110], experimental SE [72,104,107,[111][112][113][114][115][116] and human TLE (TLE) [117][118][119]. ...
Background
Erythropoietin (Epo) and vascular endothelial growth factor (VEGF) are two vasoactive molecules with essential trophic effects for brain development. The expression and secretion of both molecules increase in response to neuronal damage and they exert protective and restorative effects, which may also be accompanied by adverse side effects.
Objective
We review the most relevant evidence on the neuroprotective and neurorestorative effects of Epo and VEGF in three of the most frequent neurological disorders, namely, stroke, epilepsy and Alzheimer's disease, to develop new therapeutic approaches.
Method
Several original scientific manuscripts and reviews that have discussed the evidence in critical way, considering both the beneficial and adverse effects of Epo and VEGF in the selected neurological disorders, were analysed. In addition, throughout this review, we propose several considerations to take into account in the design of therapeutic approaches based on Epo and VEGF signalling.
Results
Although the three selected disorders are triggered by different mechanisms, they evolve through similar processes: excitotoxicity, oxidative stress, neuroinflammation, neuronal death, glial reactivity and vascular remodelling. Epo and VEGF exert neuroprotective and neurorestorative effects by acting on these processes due to their pleiotropism. In general, the evidence shows that both Epo and VEGF reduce neuronal death but that at the vascular level, their effects are contradictory.
Conclusion
Because the Epo and VEGF signalling pathways are connected in several ways, we conclude that more experimental studies, primarily studies designed to thoroughly assess the functional interactions between Epo and VEGF in the brain under both physiological and pathophysiological conditions, are needed.
This paper addresses the problem of making statistical inference about a population that can only be identified through classifier predictions. The problem is motivated by scientific studies in which human labels of a population are replaced by a classifier. For downstream analysis of the population based on classifier predictions to be sound, the predictions must generalize equally across experimental conditions. In this paper, we formalize the task of statistical inference using classifier predictions, and propose bootstrap procedures to allow inference with a generalizable classifier. We demonstrate the performance of our methods through extensive simulations and a case study with live cell imaging data.
