Hypoxia and hyperoxia differentially control proliferation of rat neural crest stem cells via distinct regulatory pathways of the HIF1[alpha]-CXCR4 and TP53-TPM1 proteins

• Published in: Developmental dynamics 2017-03, Vol.246 (3), p.162
• Main Authors: Chen, Chien-Cheng, Hsia, Ching-Wu, Ho, Cheng-Wen, Liang, Chang-Min, Chen, Chieh-Min, Huang, Kun-Lun, Kang, Bor-Hwang, Chen, Yi-Hui
• Format: Article
• Language: English
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.24481

Background: Neural crest stem cells (NCSCs) are a population of adult multipotent stem cells. We are interested in studying whether oxygen tensions affect the capability of NCSCs to self-renew and repair damaged tissues. NCSCs extracted from the hair follicle bulge region of the rat whisker pad were cultured in vitro under different oxygen tensions. Results: We found significantly increased and decreased rates of cell proliferation in rat NCSCs (rNCSCs) cultured, respectively, at 0.5% and 80% oxygen levels. At 0.5% oxygen, the expression of both hypoxia-inducible factor (HIF) 1[alpha] and CXCR4 was greatly enhanced in the rNCSC nuclei and was suppressed by incubation with the CXCR4-specific antagonist AMD3100. In addition, the rate of cell apoptosis in the rNCSCs cultured at 80% oxygen was dramatically increased, associated with increased nuclear expression of TP53, decreased cytoplasmic expression of TPM1 (tropomyosin-1), and increased nuclear-to-cytoplasmic translocation of S100A2. Incubation of rNCSCs with the antioxidant N-acetylcysteine (NAC) overcame the inhibitory effect of 80% oxygen on proliferation and survival of rNCSCs. Conclusions: Our results show for the first time that extreme oxygen tensions directly control NCSC proliferation differentially via distinct regulatory pathways of proteins, with hypoxia via the HIF1[alpha]-CXCR4 pathway and hyperoxia via the TP53-TPM1 pathway. Developmental Dynamics 246:162-185, 2017. © 2016 Wiley Periodicals, Inc. Key Findings Hypoxia (0.5% O2) upregulates nuclear expression of HIF1[alpha], CXCR4 and CDKN1A (p21CIP1/WAF1), increases plasma membrane expression of CXCR4, and increases viability and proliferation of rat neural crest stem cells. Inhibition of Hif1[alpha] or Cxcr4 expression by siRNA transfection, or inhibition of nuclear translocation of CXCR4 by the specific antagonist AMD3100, was sufficient to prevent the increased proliferation of rat neural crest stem cells under hypoxia. Hyperoxia (80% O2) induces nuclear-to-cytoplasmic translocation of S100A2, decreases TPM1 (tropomyosin-1) expression, increases nuclear expression of TP53 and CDKN1A, and decreases proliferation and increases apoptosis of rat neural crest stem cells. Inhibition of TP53 expression by the antioxidant N-acetylcysteine or Tp53 siRNA was sufficient to prevent the increased apoptosis and decreased proliferation of rat neural crest stem cells under hyperoxia.