Abstract
Purpose:
Epithelial Mesenchymal Transition (EMT) is known to play an important role in the wound healing process. There is evidence to suggest that differentiated epithelial cells which undergo EMT can gain the stem cell-like properties. Separately, there is evidence demonstrating the existence of stem/progenitor cells in injured mouse LGs. Current experiment was designed to ascertain if EMT is involved in the activation of stem/progenitor cells in rabbit LGs after ligation induced injury.
Methods:
Male and female New Zealand White rabbits (aged 6-8 weeks) were randomly divided into ligation group and intact group. Interlobar ducts of the LGs in ligation group were ligated. After 3 days, ligated ducts were reopened. Subsequently, the LGs were harvested on day 7 after reopening for further analyses - immunohistochemistry (IHC), Flow cytometry (FC), quantitative real-time reverse-transcription PCR (Q-RT-PCR) studies. Epithelial cells undergoing EMT-like changes were identified by double immunostaining for α-smooth muscle actin (α-SMA)/Vimentin and Pancytokeratin. In addition, flow cytometry was used to measure the rates of α-smooth muscle actin (α-SMA)/Vimentin and Pancytokeratin positive subpopulations. Q-RT-PCR study was used to explore different genes involved in EMT: the change of genes considered to be part of WNT/β-catenin signal pathway were detected by the expression LRP5, WNT1, β-catenin, DKK1; E-cadherin and the transcriptional repressor of E-cadherin, Snail2 and Sox9, were also detected in mRNA level.
Results:
In contrast to the intact lacrimal group, ductal ligation group was observed to have a higher number of α-SMA/Vimentin and Pancytokeratin positive cells. WNT/β- catenin signal pathway related genes - LRP5, WNT1, β-catenin, DKK1 - increased in the ductal ligation group. Analysis of mRNA expression revealed a significant down-regulation of E-cadherin and up-regulation of Snail2 and Sox9.
Conclusions:
We concluded that EMT is involved in the activation of stem/progenitor cells in rabbit LGs after ligation induced injury.
Keywords: 512 EMT (epithelial mesenchymal transition)