AKT activation by N-cadherin regulates beta-catenin signaling and neuronal differentiation during cortical development

Abstract

BackgroundDuring cerebral cortical development, neural precursor-precursor interactions in the ventricular zone neurogenic niche coordinate signaling pathways that regulate proliferation and differentiation. Previous studies with shRNA knockdown approaches indicated that N-cadherin adhesion between cortical precursors regulates β-catenin signaling, but the underlying mechanisms remained poorly understood.ResultsHere, with conditional knockout approaches, we find further supporting evidence that N-cadherin maintains β-catenin signaling during cortical development. Using shRNA to N-cadherin and dominant negative N-cadherin overexpression in cell culture, we find that N-cadherin regulates Wnt-stimulated β-catenin signaling in a cell-autonomous fashion. Knockdown or inhibition of N-cadherin with function-blocking antibodies leads to reduced activation of the Wnt co-receptor LRP6. We also find that N-cadherin regulates β-catenin via AKT, as reduction of N-cadherin causes decreased AKT activation and reduced phosphorylation of AKT targets GSK3β and β-catenin. Inhibition of AKT signaling in neural precursors in vivo leads to reduced β-catenin-dependent transcriptional activation, increased migration from the ventricular zone, premature neuronal differentiation, and increased apoptotic cell death.ConclusionsThese results show that N-cadherin regulates β-catenin signaling through both Wnt and AKT, and suggest a previously unrecognized role for AKT in neuronal differentiation and cell survival during cortical development.

PDK1–Akt pathway regulates radial neuronal migration and microtubules in the developing mouse neocortex

“…The PDK1-Akt pathway contributes to the regulation of proliferation, survival, differentiation of, and metabolism in various cell types (22,25,36), but its role in neuronal migration has been unclear. We demonstrated a role for the PDK1-Akt pathway in neocortical neurons through the specific manipulation of postmitotic cells with the use of Nex Cre/+ mice or a Neurod1 promoterdependent Cre expression plasmid.…”

“…In addition, the extracellular matrix component laminin γ1 and its integrin receptor might function upstream of the PDK1-Akt pathway during neuronal migration (46). Furthermore, given that N-cadherin mediates neuron-glial cell adhesion and regulates Akt activation (36,47), Akt might be activated at sites of such adhesion in an N-cadherindependent manner. Although previous work suggested that Akt might function downstream of Reelin during cortical development (38), PDK1 ablation resulted in a layering defect distinct from that of reeler mutants, suggesting that Akt is not a central effector of Reelin signaling, at least during radial neuronal migration.…”

N-cadherin-based adherens junction regulates the maintenance, proliferation, and differentiation of neural progenitor cells during development

“…37,40,41 Furthermore, loss of function of N-cadherin by the conditional knockout (KO) and short hairpin RNA (shRNA) in the cerebral cortex, causes premature differentiation of NPCs. 84, 93 These results demonstrate that N-cadherin plays a critical role in the self-supportive niche to keep the identity of NPCs.…”

Akt Inhibitor MK2206 Prevents Influenza pH1N1 Virus Infection In Vitro

“…Therefore, we evaluated the effect of MK2206 on the phosphorylation status of Akt and several of its downstream targets, including AMP-activated protein kinase (AMPK), ␤-catenin, CREB-1, endothelial nitric oxide synthase (eNOS), extracellular signal-regulated kinase (ERK), focal adhesion kinase (FAK), glycogen synthase kinase 3 (GSK3), HSP27, P70S6, PRAS40, TOR, and WNK1 (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33) in NCI-H1666 cells infected with A/Helsinki/P14/2009 for 0.5 h in the presence of absence of MK2206 and using mock-infected cells as controls. Phospho-proteome profiling revealed that MK2206 treatment did not affect the phosphorylation status of Akt but lowered the phosphorylation levels of its targets, PRAS40 and WNK1 ( Fig.…”