Valosin-containing protein is a key mediator between autophagic cell death and apoptosis in adult hippocampal neural stem cells following insulin withdrawal.

Bo Kyoung Yeo,Kyung Min Chung,Seonghee Jung,Hanwoong Woo,Seong-Woon Yu,Eun-Kyoung Kim,Caroline Jeeyeon Hong,Kyungchan Kim

doi:10.1186/s13041-016-0212-8

Bo Kyoung Yeo, Kyung Min Chung + Show 6 more

Open Access

https://doi.org/10.1186/s13041-016-0212-8

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Abstract

BackgroundProgrammed cell death (PCD) plays essential roles in the regulation of survival and function of neural stem cells (NSCs). Abnormal regulation of this process is associated with developmental and degenerative neuronal disorders. However, the mechanisms underlying the PCD of NSCs remain largely unknown. Understanding the mechanisms of PCD in NSCs is crucial for exploring therapeutic strategies for the treatment of neurodegenerative diseases.ResultWe have previously reported that adult rat hippocampal neural stem (HCN) cells undergo autophagic cell death (ACD) following insulin withdrawal without apoptotic signs despite their normal apoptotic capabilities. It is unknown how interconnection between ACD and apoptosis is mediated in HCN cells. Valosin-containing protein (VCP) is known to be essential for autophagosome maturation in mammalian cells. VCP is abundantly expressed in HCN cells compared to hippocampal tissue and neurons. Pharmacological and genetic inhibition of VCP at basal state in the presence of insulin modestly impaired autophagic flux, consistent with its known role in autophagosome maturation. Of note, VCP inaction in insulin-deprived HCN cells significantly decreased ACD and down-regulated autophagy initiation signals with robust induction of apoptosis. Overall autophagy level was also substantially reduced, suggesting the novel roles of VCP at initial step of autophagy.ConclusionTaken together, these data demonstrate that VCP may play an essential role in the initiation of autophagy and mediation of crosstalk between ACD and apoptosis in HCN cells when autophagy level is high upon insulin withdrawal. This is the first report on the role of VCP in regulation of NSC cell death. Elucidating the mechanism by which VCP regulates the crosstalk of ACD and apoptosis will contribute to understanding the molecular mechanism of PCD in NSCs.

Highlights

Programmed cell death (PCD) plays essential roles in the regulation of survival and function of neural stem cells (NSCs)
Valosin-containing protein (VCP) is highly expressed in hippocampal neural stem (HCN) cells and degraded by autophagy following insulin withdrawal Since VCP has not been studied in NSCs before, first, we examined the expression level of VCP in HCN cells
VCP was highly expressed in HCN stem cells in vitro, compared to the total hippocampal tissue derived from 8-week-old rat and embryonic hippocampal primary neurons after 9 days in vitro (Fig. 1a)

Summary

Introduction

Programmed cell death (PCD) plays essential roles in the regulation of survival and function of neural stem cells (NSCs). Abnormal regulation of this process is associated with developmental and degenerative neuronal disorders. Programmed cell death (PCD) is a deliberate cellular suicide process. The components are sequestered by autophagosomes, which fuse with lysosomes for degradation. This process usually occurs in response to cellular stress to protect the cells. Type III cell death, called necrosis, is best defined by abnormal mitochondria morphology, swollen and ruptured cellular membrane, cell lysis and exposure of intracellular content to the extracellular space. Inflammatory reactions are frequently related with necrosis [6]

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