Analysis Of The Function Of Mab21L2 In Human Lens Epithelium Cell Differentiation

Previous study has shown that Mab21L2 plays a key role in ocular, especially lens development. However, the molecular mechanism implicated in Mab21L2-mediated regulation of lens development remains elusive. HLE, a human lens epithelium cell line transformed by SV40 large T antigen, is widely used as a model system to explore the molecular mechanisms of lens differentiation under different conditions.With this system, the function of Mab21L2 in lens differentiation was explored. The purified expression plasmid of Mab21L2 and its vector were separately introduced into HLE cells, and stable clones of the cell lines were established under selection of neomycin (400μg/ml). The over-expression of Mab21L2 in the selected clones was confirmed via RT-PCR and Western blot analysis. Introduction of Mab21L2 into HLE cells induced differentiation of the transfected cells as reflected by the morphology. To further explore the function of Mab21L2 in mediating lens differentiation, the vector and Mab21L2-transfected cells were treated by basic-FGF at various concentrations. The presence of Mab21L2 enhances HLE sensitivity to basic FGF. Under the same concentration of basic-FGF, over-expression of Mab21L2 accelerates differentiation of the treated cells and shortened the differentiation time from a normal 5-day induction with the vector-transfected cells to a 3-day induction. Western Blot analysis indicates that the expression profile of pERK1/2 kinases were significantly varied in vector and Mab21L2-transfected cells with basic-FGF induction. While the expression level of pERKl/2 was greatly suppressed in Mab21L2-transfected cells without FGF-basic treatment, the expression level of pERKl/2 of over-expression cell was tremendously enhanced after 1 or 2day treatment to be obviously higher than that of control cell. However, the expression level of pERK1/2 decline again after 4-day-treatment. In addition, the expression profile of B56γand MEK2 in overexpression cells significantly differ from that of control cells, high MEK2 expression leads to up-regulation of the expression of pERKl/2. In contrast, when the expression level of B56y was high, the expression of pERK was down-regulated. These findings not only provide insights into the important role that Mab21L2 plays in accelerating lens epithelium differentiation, but also enlighten us on some of the putative molecular mechanisms:Mab21L2 accelerate lens differentiation through precise regulation of B56y and MEK2 expression to mediate both positive and negative regulation of pERK1/2 in different FGF-basic induced differentiation stage.