scholarly journals Bioenergetic Requirements and Spatiotemporal Profile of Nerve Growth Factor Induced PI3K-Akt Signaling Along Sensory Axons

2021 ◽  
Vol 14 ◽  
Author(s):  
Rajiv Sainath ◽  
Gianluca Gallo
Keyword(s):  
Steady State ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Oxidative Phosphorylation ◽  
High Amplitude ◽  
Akt Signaling ◽  
Nerve Growth ◽  
Kinase Activation ◽  
Akt Phosphorylation ◽  
Initiation Phase

Nerve Growth Factor (NGF) promotes the elaboration of axonal filopodia and branches through PI3K-Akt. NGF activates the TrkA receptor resulting in an initial transient high amplitude burst of PI3K-Akt signaling followed by a maintained lower steady state, hereafter referred to as initiation and steady state phases. Akt initially undergoes phosphorylation at T308 followed by phosphorylation at S473, resulting in maximal kinase activation. We report that during the initiation phase the localization of PI3K signaling, reported by visualizing sites of PIP3 formation, and Akt signaling, reflected by Akt phosphorylation at T308, correlates with the positioning of axonal mitochondria. Mitochondrial oxidative phosphorylation but not glycolysis is required for Akt phosphorylation at T308. In contrast, the phosphorylation of Akt at S473 is not spatially associated with mitochondria and is dependent on both oxidative phosphorylation and glycolysis. Under NGF steady state conditions, maintenance of phosphorylation at T308 shows dual dependence on oxidative phosphorylation and glycolysis. Phosphorylation at S473 is more dependent on glycolysis but also requires oxidative phosphorylation for maintenance over longer time periods. The data indicate that NGF induced PI3K-Akt signaling along axons is preferentially initiated at sites containing mitochondria, in a manner dependent on oxidative phosphorylation. Steady state signaling is discussed in the context of combined contributions by mitochondria and the possibility of glycolysis occurring in association with endocytosed signalosomes.

scholarly journals Different Outcomes of Unliganded and Liganded Estrogen Receptor-α on Neurite Outgrowth in PC12 Cells

Endocrinology ◽  
2008 ◽  
Vol 150 (1) ◽  
pp. 200-211 ◽  
Author(s):  
Yohann Mérot ◽  
François Ferrière ◽  
Luc Gailhouste ◽  
Guillaume Huet ◽  
Frédéric Percevault ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Signaling Pathways ◽  
Neurite Outgrowth ◽  
Pc12 Cells ◽  
Estrogen Receptor Α ◽  
Akt Signaling ◽  
Induced Response ◽  
Nerve Growth

A precise description of the mechanisms by which estrogen receptor-α (ERα) exerts its influences on cellular growth and differentiation is still pending. Here, we report that the differentiation of PC12 cells is profoundly affected by ERα. Importantly, depending upon its binding to 17β-estradiol (17βE2), ERα is found to exert different effects on pathways involved in nerve growth factor (NGF) signaling. Indeed, upon its stable expression in PC12 cells, unliganded ERα is able to partially inhibit the neurite outgrowth induced by NGF. This process involves a repression of MAPK and phosphatidylinositol 3-kinase/Akt signaling pathways, which leads to a negative regulation of markers of neuronal differentiation such as VGF and NFLc. This repressive action of unliganded ERα is mediated by its D domain and does not involve its transactivation and DNA-binding domains, thereby suggesting that direct transcriptional activity of ERα is not required. In contrast with this repressive action occurring in the absence of 17βE2, the expression of ERα in PC12 cells allows 17βE2 to potentiate the NGF-induced neurite outgrowth. Importantly, 17βE2 has no impact on NGF-induced activity of MAPK and Akt signaling pathways. The mechanisms engaged by liganded ERα are thus unlikely to rely on an antagonism of the inhibition mediated by the unliganded ERα. Furthermore, 17βE2 enhances NGF-induced response of VGF and NFLc neuronal markers in PC12 clones expressing ERα. This stimulatory effect of 17βE2 requires the transactivation functions of ERα and its D domain, suggesting that an estrogen-responsive element-independent transcriptional mechanism is potentially relevant for the neuritogenic properties of 17βE2 in ERα-expressing PC12 cells. In the absence of its ligand, ERα partially inhibits the nerve growth factor-induced neurite outgrowth of PC12 cells, whereas, once liganded, it enhances differentiation.

scholarly journals Nitric Oxide Synthase Inhibitors Modulate Nerve-Growth-Factor Mediated Activation of Akt

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Cheryl L. Cragg ◽  
Janet C. MacKinnon ◽  
Bettina E. Kalisch
Keyword(s):  
Nitric Oxide ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Cell Lines ◽  
Nerve Growth ◽  
Akt Phosphorylation ◽  
Map Kinase Pathway ◽  
Kinase Pathway

Nitric oxide (NO) modulates nerve-growth-factor- (NGF-) mediated signaling and gene expression. In the present paper, the role of NO in NGF-mediated Akt activation in PC12 and IMR32 cells was investigated. Cells were treated with NGF (50 ng/mL) in the presence or absence of NO synthase (NOS) inhibitors and Akt phosphorylation assessed by western blot analysis. In both cell lines, Akt was phosphorylated within 15 min of NGF treatment. In PC12 cells, this level of phosphorylation was sustained for 60 min, while in IMR32 cells, the activation decreased after 30 min of NGF treatment. The nonselective NOS inhibitor Nω-nitro-L-arginine methylester (L-NAME; 20 mM) had no effect on NGF-mediated Akt phosphorylation in PC12 cells but in combination with NGF, the iNOS selective inhibitor s-methylisothiourea (S-MIU; 2.0 mM) maintained Akt phosphorylation up to 2 h. In IMR32 cells, both L-NAME and S-MIU prolonged the activation of Akt. Pretreatment with 50 μM U0126, a MAP kinase pathway inhibitor, also increased the activation of Akt in both cell lines. These data suggest that NO modulates the duration of phosphorylation of Akt in response to NGF and that this effect may, in part, be mediated by the effects of NO on the Ras-MAP kinase pathway.

Nerve growth factor-induced circadian phase shifts and MAP kinase activation in the hamster suprachiasmatic nuclei

2005 ◽  
Vol 22 (3) ◽  
pp. 665-671 ◽  
Author(s):  
Gastón A. Pizzio ◽  
Ernesto C. Hainich ◽  
Santiago A. Plano ◽  
Martin R. Ralph ◽  
Diego A. Golombek
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Map Kinase ◽  
Phase Shifts ◽  
Suprachiasmatic Nuclei ◽  
Nerve Growth ◽  
Kinase Activation ◽  
Circadian Phase

scholarly journals Nerve growth factor regulates both the phosphorylation and steady-state levels of microtubule-associated protein 1.2 (MAP1.2).

1988 ◽  
Vol 106 (5) ◽  
pp. 1573-1581 ◽  
Author(s):  
J M Aletta ◽  
S A Lewis ◽  
N J Cowan ◽  
L A Greene
Keyword(s):  
Steady State ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Pc12 Cell ◽  
Total Cell ◽  
Microtubule Assembly ◽  
Cell Protein ◽  
Nerve Growth ◽  
Sds Page

This study characterizes effects of nerve growth factor (NGF) on the steady-state level and phosphorylation of a high molecular mass microtubule-associated protein in PC12 rat pheochromocytoma cells. Past work showed that NGF significantly raises the relative levels of this phosphoprotein, designated MAP1.2, with a time course similar to that of neurite outgrowth. To study this in greater detail, MAP1.2 in PC12 cell lysates was resolved by SDS-PAGE in gels containing 3.25% acrylamide/4 M urea and identified by comigration with material immunoprecipitated from the lysates by MAP1 antibodies. Quantification by metabolic radiolabeling with [35S]methionine or by silver staining revealed a 3.0-3.5-fold increase in MAP1.2 levels relative to total cell protein after NGF treatment for 2 wk or longer. A partial increase was detectable after 3 d, but not after 2 h of NGF exposure. As measured by incorporation of [32P]phosphate, NGF had a dual effect on MAP1.2. Within 15 min to 2 h, NGF enhanced the incorporation of phosphate into MAP1.2 by two- to threefold relative to total cell phosphoproteins. This value slowly increased thereafter so that by 2 wk or more of NGF exposure, the average enhancement of phosphate incorporation per MAP1.2 molecule was over fourfold. The rapid action of NGF on MAP1.2 could not be mimicked by either epidermal growth factor, a permeant cAMP derivative, phorbol ester, or elevated K+, each of which alters phosphorylation of other PC12 cell proteins. SDS-PAGE revealed multiple forms of MAP1.2 which, based on the effects of alkaline phosphatase on their electrophoretic mobilities, differ, at least in part, in extent of phosphorylation. Before NGF treatment, most PC12 cell MAP1.2 is in more rapidly migrating, relatively poorly phosphorylated forms. After long-term NGF exposure, most is in more slowly migrating, more highly phosphorylated forms. The effects of NGF on the rapid phosphorylation of MAP1.2 and on the long-term large increase in highly phosphorylated MAP1.2 forms could play major functional roles in NGF-mediated neuronal differentiation. Such roles may include effects on microtubule assembly, stability, and cross-linking and, possibly for the rapid effects, nuclear signaling.

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