Role of senkyunolide I in the promotion of neural stem/progenitor cell proliferation via the Akt/β-catenin pathway

Abstract

Following brain injury, neural stem cells (NSCs) can generate mature neurons and replace damaged cells. However, the capacity of endogenous NSCs to self-repair from injured brain is limited as most NSCs die before becoming mature neurons. Therefore, a boosting endogenous NSCs by pharmacological support offers the potential to repair the damaged brain. Recently, small molecules have hold considerable promise for neuron regeneration and repair as they can penetrate the blood-brain barrier easily. Senkyunolide I (SEI) is a bioactive constituent derived from traditional Chinese medicines Ligusticum chuanxiong Hort. and Angelica sinensis (Oliv.) Diels, and was found to able to prevent ischemic stroke. This study examined the effects of SEI on the proliferation and neuronal lineage differentiation of prepared neural stem/progenitor cells (NS/PCs). The NS/PC proliferation was determined by 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt, and neurosphere formation assays. The NS/PC differentiation was also investigated by immunocytochemistry, and western blotting was employed to measure phosphorylated Akt (pAkt) and GSK-3β (pGSK-3β), and active-β-catenin protein levels. We showed that the NS/PC proliferation was enhanced after SEI exposure. Elevated cell numbers were also observed in neurospheres, which were incubated with SEI for 3 days, whereas the NS/PC differentiation was decreased after SEI exposure for 5 days. Furthermore, SEI upregulated pAkt/Akt and active-β-catenin levels and increased NS/PC proliferation after SEI treatment was reversed by phosphatidylinositol 3-kinase inhibitor LY294002. downregulated differentiated processes. Thus, SEI promoted the NS/PC proliferation and suppressed NS/PC differentiation into neurons and/or astrocytes, therefore SEI could be an interesting and promising candidate for stimulating NSCs.

Keywords: Akt; Neural stem/progenitor cells; Neurogenesis; Senkyunolide I; β-catenin.