Involvement of Cold Inducible RNA-Binding Protein in Severe Hypoxia-Induced Growth Arrest of Neural Stem Cells In Vitro

Abstract

Neonatal hypoxia is the leading cause of brain damage with birth complications. Many studies have reported proliferation-promoting effect of mild hypoxia on neural stem cells (NSCs). However, how severe hypoxia influences the behavior of NSCs has been poorly explored. In the present study, we investigated the effects of 5, 3, and 1 % oxygen exposure on NSCs in vitro. MTT, neurosphere assay, and 5-ethynyl-2′-deoxyuridine (EdU) incorporation revealed a quick growth arrest of C17.2 cells and primary NSCs induced by 1 % oxygen exposure. Cell cycle analysis showed that this hypoxia exposure caused a significant increase of cells in G0/G1 phase and decrease of cells in S phase that is associated with decrease of Cyclin D1. Interestingly, the expression of cold inducible RNA-binding protein (CIRBP), a cold responsive gene reacting to multiple cellular stresses, was decreased in parallel with the 1 % oxygen-induced proliferation inhibition. Forced expression of CIRBP under hypoxia could restore the proliferation of NSCs, as showed by EdU incorporation and cell cycle analysis. Furthermore, the expression of Cyclin D1 under hypoxia was also restored by CIRBP overexpression. Taken together, these data suggested a growth-suppressing effect of severe hypoxia on NSCs and, for the first time, revealed a novel role of CIRBP in hypoxia-induced cell cycle arrest, suggesting that modulating CIRBP may be utilized for preventing hypoxia-induced neonatal brain injury.

RNA sequencing and proteomics approaches reveal novel deficits in the cortex of Mecp2-deficient mice, a model for Rett syndrome

“…Each of these proteins was significantly upregulated in RTT tissue relative to WT. In particular, cold-inducible RNA-binding protein (CIRBP), an RNA-binding protein upregulated in response to hypoxia [ 70 ], shows one of the largest fold increases in our data set (4.3-fold; Table 2 ). Interestingly, this protein has previously been shown to be upregulated in RTT tissue [ 21 ], although mRNA levels do not appear to be affected ([ 71 ] and our data).…”

Retracted: Ganoderic acid A alleviates hypoxia‐induced apoptosis, autophagy, and inflammation in rat neural stem cells through the PI3K/AKT/mTOR pathways

“…NSCs are mainly reserved in the subventricular zone, and the region of subventricular zone is at its maximum size at neonatal stage (Zerlin, Levison, & Goldman, ). Substantial evidence has reported that neurons and oligodendrocytes suffer apoptotic status under hypoxia condition (Tan, Guo, & Liu, ; Zhang et al, ). Considering that NSCs are the major cell type that can regenerate lost nerve cells, we explored the potential therapeutic drug for HIE in hypoxia‐treated NSCs.…”

“…NSCs are mainly reserved in the subventricular zone, and the region of subventricular zone is at its maximum size at neonatal stage (Zerlin, Levison, & Goldman, 1995). Substantial evidence has reported that neurons and oligodendrocytes suffer apoptotic status under hypoxia condition (Tan, Guo, & Liu, 2013;Zhang et al, 2017).…”

Cold-inducible proteins CIRP and RBM3, a unique couple with activities far beyond the cold

“…Experimentally, both mild (8 %) and severe (1 %) hypoxia can induce CIRP and RBM3 expression to a comparable level by a mechanism that involves neither hypoxia-inducible factor (HIF) nor mitochondria in vitro [ 54 ]. In contrast, severe hypoxia mimicking ischemia in an in vitro model applying cultured neural stem cells (NSCs) suppresses CIRP expression in parallel with cell cycle arrest [ 55 ]. Since hydrogen peroxide treatment can inhibit the hypothermia-induced expression of CIRP [ 56 , 57 ] and a mild level of reactive oxygen species (ROS) is beneficial, whereas a high level is toxic for NSC proliferation, it has been hypothesized that mild hypoxia resulting in mild elevation of ROS increases CIRP expression, whereas severe hypoxia/ischemia inducing an overload of ROS suppresses CIRP expression [ 55 ].…”

“…In contrast, severe hypoxia mimicking ischemia in an in vitro model applying cultured neural stem cells (NSCs) suppresses CIRP expression in parallel with cell cycle arrest [ 55 ]. Since hydrogen peroxide treatment can inhibit the hypothermia-induced expression of CIRP [ 56 , 57 ] and a mild level of reactive oxygen species (ROS) is beneficial, whereas a high level is toxic for NSC proliferation, it has been hypothesized that mild hypoxia resulting in mild elevation of ROS increases CIRP expression, whereas severe hypoxia/ischemia inducing an overload of ROS suppresses CIRP expression [ 55 ]. Exposing pregnant mice in late gestation to severe systemic hypoxia causes overexpression of HIF-dependent genes and downregulation of RBM3 expression in the placenta and developing brain [ 58 ].…”