고포도당 처리 인간 제대혈 유래 중간엽 줄기세포의 E-cadherin 발현 변화와 피부 상처 치유 효능

Abstract

Glucose plays an important role in stem cell fate determination and its behavior. Stem cell fate is regulated by genes involved in differentiation, proliferation, and migration. Previous investigators have suggested that oxidative stress, especially reactive oxygen species (ROS), increases stem cell migration and the increase of ROS may destroy the homeostasis of the cells, and subsequently serious damage in the cells. High glucose is the cause of excess ROS that leads to diabetic complications. 17β-estradiol (E2) is an important regulator of energy homeostasis and glucose metabolism, so that it should be considered a suitable target of E2 for preventing or treating metabolic disorders. Diabetes is closely related to oxidative stress and the risk of diabetes is high in patients who are deficient in E2. Thus, E2 has protective roles against oxidative stress exposure which leads to mitochondrial dysfunction and damage. However, it remains unclear how glucose contributes to the precise molecular mechanism for producing ROS in the stem cell and E2 evokes protective antioxidant mechanisms. Therefore, present study aimed to investigate 1) the effect of high glucose on stem cell migration and its related signaling pathways, 2) the role of E2 in glucose-mediated mitochondrial ROS (mtROS) level in human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs), and 3) the effect of hUCB-MSC transplantation on mouse skin wound healing by E2 in ovariectomized (OVX) diabetic mice in vivo. <br/> First, I investigated the effect of high glucose on regulation of hUCB-MSC migration. High glucose treatment (D-glucose) induced hUCB-MSC migration, expression of cleaved Notch, Snail and enhancer of zeste homolog2 (EZH2), but repressed epithelial cadherin (E-cadherin) expression. E-cadherin repression was regulated by high glucose through Snail and EZH2 upregulation, and Snail was modulated in parallel with EZH2 in hUCB-MSCs. Next, I demonstrated that high glucose enhanced ROS, which activates either c-Jun N-terminal kinase (JNK) or phosphatidylinositol-3-kinses (PI3K)/protein kinase B (Akt) signaling. High glucose-induced JNK activation elicit the cleavage of Notch protein through γ–secretase activation, following Notch intracellular domain (NICD) translocation into the nucleus. In the nucleus, Snail interacted with polycomb repressive complex 2 (PRC2) components by high glucose. And then EZH2, one of the major component of PRC2, and Snail bound with E-box of the E-cadherin promoter by high glucose, which in turn causes E-cadherin repression. Taken together, these results suggest that high glucose-induced ROS production increases the migration of hUCB-MSCs through E-cadherin repression via EZH2 and Snail upregulation. <br/> Next, I investigated the role of E2 on mtROS-mediated autophagic cell death by high glucose in hUCB-MSCs. High glucose increased mtROS to upregulate Beclin1 and LC-II expression, leading to decreased cell viability. In contrast, E2 treatment significantly decreased high glucose-induced mtROS levels and subsequently restored cell viability, suggesting that E2 serves as a strong antioxidant. I found that treatment of both E2 and high glucose promoted ERα translocation into the nucleus leading to increased Nrf2 in the nucleus. However, high glucose produced mtROS via downregulating Nrf2 nuclear translocation. This subsequently culminated in Sirtuin3 (Sirt3) downregulation and manganese superoxide dismutase (MnSOD) acetylation. The increased nuclear translocation of Nrf2 triggered upregulation of Sirt3 expression and activated MnSOD