p(FPLX:PI3K)

Entity

Name

PI3K

Namespace

FPLX

Namespace Version

20180917

Namespace URL

https://raw.githubusercontent.com/sorgerlab/famplex/e8ae9926ff95266032cb74f77973c84939bffbeb/export/famplex.belns

An ever-growing body of evidence indicates that in CNS and parasympathetic nervous system neurons and in heterologous systems expressing specific nAChR subtypes, nicotine stimulates several Ca2+-dependent kinases, including PI3K, protein kinase C (PKC), protein kinase A (PKA), calmodulin-dependent protein kinase II (CAM kinase II), and extracellular signal-regulated kinases (ERKs; Refs. 108, 112, 146, 318, 469). PubMed:19126755

From these findings, it would seem that FYN plays a neuroprotective role. However, FYN may also play a paradoxical role in Abeta toxicity. Indeed, Abeta activates both FYN and the PI3K cascade (Williamson et al., 2002), whereas germline knockout of FYN is neuroprotective in mice (Lambert et al., 1998; Chin et al., 2004). FYN knockout protects mature mouse neurons in organotypic central nervous system cultures (Lambert et al., 1998). PubMed:19293145

For instance, over-expressing PI3K in Drosophila melanogaster neurons in situ results in an increase in functional synapses as well as synaptic sprouting (Martín-Pen˜ a et al., 2006). Thus it is possible that nicotine’s activation of the PI3K pathway results in increased synaptic stability, and it would be of interest to explore this further in vertebrates. Thus, the evidence suggests that activation of nAChRs activates the PI3K/AKT pathway to favor antiapoptotic pathways and possibly induce synaptogenesis. PubMed:19293145

For instance, over-expressing PI3K in Drosophila melanogaster neurons in situ results in an increase in functional synapses as well as synaptic sprouting (Martín-Pen˜ a et al., 2006). Thus it is possible that nicotine’s activation of the PI3K pathway results in increased synaptic stability, and it would be of interest to explore this further in vertebrates. Thus, the evidence suggests that activation of nAChRs activates the PI3K/AKT pathway to favor antiapoptotic pathways and possibly induce synaptogenesis. PubMed:19293145

In a microarray study comparing brains from patients with AD with control brains, FYN was found to be significantly upregulated in AD (Wang et al., 2003a). In this context, it is of interest that FYN has also been shown to activate the PI3K/AKT cascade, thereby inhibiting apoptosis (Tang et al., 2007). Indeed, FYN is required for phos- phorylation of phosphoinositide 3-kinase enhancer (PIKE), which itself regulates AKT (Fig. 3). PIKE binds to AKT and up-regulates its kinase a ctivity, thereby reducing apoptosis. Phosphorylation protects PIKE from caspase cleavage, hence FYN is antiapoptotic (Tang et al., 2007). PubMed:19293145

Specifically, it has been shown that upon stimulation, α7 AChR activates PI3K via direct association with non-receptor type tyrosine kinase FYN and Janus-activated kinase 2 (JAK2), promoting the survival of neuronal cells (Fig. 3). PubMed:22040696

Specifically, it has been shown that upon stimulation, α7 AChR activates PI3K via direct association with non-receptor type tyrosine kinase FYN and Janus-activated kinase 2 (JAK2), promoting the survival of neuronal cells (Fig. 3). PubMed:22040696

An unusual approach to augmenting autophagosome formation is represented by the brain- penetrant autophagy enhancer 99 (AUTEN-99), which blocks myotubularin-related protein 14 (MTMR14, also known as Jumpy), a phosphatase that inhibits the phos- phoinositide 3-kinase (PI3K)-mediated generation of the autophagosome membrane (FIG. 3) . AUTEN-99 aug- mented autophagic flux in isolated neurons, increased markers of autophagy in mouse brain and slowed neuro- degeneration in D. melanogaster models of PD and HD 181 . PubMed:30116051

The binding between ErbB4 and PI3K activates this latter kinase, which in turn can phosphorylate and activate its downstream target Akt PubMed:30061532

The neuroprotective effects of nicotine are blocked by inhibitors of either PI3K or SRC family kinases, and nicotine evokes an increase in levels of phosphorylated AKT, B-cell chronic lymphocytic leukemia/lymphoma (BCL2), and BCL-2-like protein (Shimohama and Kihara, 2001), which are further downstream in the PI3K/AKT pathway (Fig. 3). PubMed:19293145

Likewise, blocking the PI3K-AKT pathway inhibits the protective effects of AChE inhibitors on neuroblastoma cells or neuronal cells against Abeta (Arias et al., 2005) or L-glutamate neurotoxicity (Takada-Takatori et al., 2006). In all these studies, protection was also inhibited by nAChR blockers, suggesting that these effects are mediated by nAChRs. PubMed:19293145

In lung cancer cells, nicotine also exerts an antiapoptotic effect through activating BCL2-antagonist of cell death (BAD), a process that is inhibited by blockers of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway or the PI3K/AKT pathway (Jin et al., 2004). PubMed:19293145

For instance, over-expressing PI3K in Drosophila melanogaster neurons in situ results in an increase in functional synapses as well as synaptic sprouting (Martín-Pen˜ a et al., 2006). Thus it is possible that nicotine’s activation of the PI3K pathway results in increased synaptic stability, and it would be of interest to explore this further in vertebrates. Thus, the evidence suggests that activation of nAChRs activates the PI3K/AKT pathway to favor antiapoptotic pathways and possibly induce synaptogenesis. PubMed:19293145

For instance, over-expressing PI3K in Drosophila melanogaster neurons in situ results in an increase in functional synapses as well as synaptic sprouting (Martín-Pen˜ a et al., 2006). Thus it is possible that nicotine’s activation of the PI3K pathway results in increased synaptic stability, and it would be of interest to explore this further in vertebrates. Thus, the evidence suggests that activation of nAChRs activates the PI3K/AKT pathway to favor antiapoptotic pathways and possibly induce synaptogenesis. PubMed:19293145

ApoE-epsilon4, but not ApoE-epsilon3, disrupts carbachol-stimulated phosphoinositol (PI) hydrolysis and so does Abeta and Abeta/ApoE-epsilon4 complexes in SH-SY5Y cells (Cedazo- Mínguez and Cowburn, 2001). The effect of Abeta and its ApoE complex on PI hydrolysis were blocked by estrogen, and this disruption was itself blocked by wortmannin, suggesting that PI3K mediates estrogen’s effect on PI hydrolysis. PubMed:19293145

Specifically, it has been shown that upon stimulation, α7 AChR activates PI3K via direct association with non-receptor type tyrosine kinase FYN and Janus-activated kinase 2 (JAK2), promoting the survival of neuronal cells (Fig. 3). PubMed:22040696

An unusual approach to augmenting autophagosome formation is represented by the brain- penetrant autophagy enhancer 99 (AUTEN-99), which blocks myotubularin-related protein 14 (MTMR14, also known as Jumpy), a phosphatase that inhibits the phos- phoinositide 3-kinase (PI3K)-mediated generation of the autophagosome membrane (FIG. 3) . AUTEN-99 aug- mented autophagic flux in isolated neurons, increased markers of autophagy in mouse brain and slowed neuro- degeneration in D. melanogaster models of PD and HD 181 . PubMed:30116051

The binding between ErbB4 and PI3K activates this latter kinase, which in turn can phosphorylate and activate its downstream target Akt PubMed:30061532

The binding between ErbB4 and PI3K activates this latter kinase, which in turn can phosphorylate and activate its downstream target Akt PubMed:30061532