Abstract
BackgroundThe subcellular distribution of prorenin receptor and adaptor protein ATP6AP2 may affect neurogenesis. In this study, we hypothesized that ATP6AP2 expression and subcellular relocalization from caveolae/lipid raft microdomains (CLR-Ms) to intracellular sites may correlate with neuronal differentiation (Neu-Dif) of adipose-derived mesenchymal stem cells (ADSCs).MethodsHuman ADSCs isolated from 24 healthy donors and 24 patients with neurological disorders (ND) were cultured and induced for Neu-Dif. The mechanism of action of ATP6AP2 and the impact of its localization within the plasma membrane (particularly CLR-Ms) and intracellular sites on several pathways (mitogen-activated protein kinase, Wnt(s) signaling and others) and intracellular calcium and exosome release were evaluated. The impact of CLR-Ms on ATP6AP2 or vice versa was determined by pharmacological disruption of CLR-Ms or siATP6AP2 assays.ResultsIn patients with ND, loss of ATP6AP2 from CLR-Ms correlated with an inhibition of Neu-Dif and signaling. However, its relocalization in CLR-Ms was positively correlated to induction of Neu-Dif in healthy subjects. An apparent switch from canonical to noncanonical Wnt signaling as well as from caveolin to flotillin occurs concurrently with the increases of ATP6AP2 expression during neurogenesis. Stimulation by renin activates ERK/JNK/CREB/c-Jun but failed to induce β-catenin. Wnt5a enhanced the renin-induced JNK responsiveness. Gα proteins crosslink ATP6AP2 to caveolin where a switch from Gαi to Gαq is necessary for Neu-Dif. In ATP6AP2-enriched CLR-Ms, the release of exosomes was induced dependently from the intracellular Ca2+ and Gαq. Pharmacological disruption of CLR-M formation/stability impairs both ATP6AP2 localization and Neu-Dif in addition to reducing exosome release, indicating an essential role of ATP6AP2 enrichment in CLR-Ms for the induction of Neu-Dif. The mechanism is dependent on CLR-M dynamics, particularly the membrane fluidity. Knockdown of ATP6AP2 inhibited Neu-Dif but increased astrocytic-Dif, depleted ATP6AP2/flotillin/Gαq but accumulated caveolin/Gαi in CLR-Ms, and blocked the activation of JNK/ERK/c-Jun/CREB/exosome release. siATP6AP2 cells treated with sphingomyelinase/methyl-β-cyclodextrin reversed the levels of caveolin/flotillin in CLR-Ms but did not induce Neu-Dif, indicating the crucial relocalization of ATP6AP2 in CLR-Ms for neurogenesis. Treatment of ND-derived cells with nSMase showed reversibility in ATP6AP2 abundance in CLR-Ms and enhanced Neu-Dif.ConclusionsThis study gives evidence of the determinant role of CLR-M ATP6AP2 localization for neuronal and oligodendrocyte differentiation involving mechanisms of switches from Gαi/caveolin/canonical to Gαq/flotillin/PCP, the ERK/JNK pathway and Ca2+-dependent release of exosomes and as a potential target of drug therapy for neurodegenerative disorders.
Highlights
The subcellular distribution of prorenin receptor and adaptor protein ATP6AP2 may affect neurogenesis
Was evaluated in undifferentiated cells: ATP6AP2 mRNA was significantly reduced in human adiposederived mesenchymal stem cells (hADSCs) and hPBMCs derided from the neurological disorders (ND) group (Fig. 1a–d) in comparison to the healthy group
Positive correlations were found between Adipose-derived mesenchymal stem cell (ADSC)-expressing ATP6AP2 and PBMCexpressing ATP6AP2 in healthy (R = 0.84, P < 0.00001) and ND (R = 0.64, P < 0.001) groups (Fig. 1e, f ), indicating that the assessment of ATP6AP2 in hPBMCs can be considered a marker when the collection of adipose tissue is difficult to apply to donors with advanced ages
Summary
The subcellular distribution of prorenin receptor and adaptor protein ATP6AP2 may affect neurogenesis. ATP6AP2 was described as a renin and prorenin receptor ((P)RR) exerting a RAS-related function and as an adaptor protein between V-ATPase and Wnt receptor complex [2]. In Xenopus, ATP6AP2 is essential for mediating Wnt signaling during early central nervous system development, including neural patterning [8]. Thereby, emerging studies have drawn attention to the importance of ATP6AP2 in cognitive processes and brain development while suggesting a vital role of the RAS in learning and memory functions. Little is known about the importance of the colocalization of ATP6AP2 with key signaling factors, and even rarer are studies about its relocalization and its relationship with plasma membrane microdomains in MSCs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
