| Summary: | 碩士 === 長庚大學 === 生物醫學研究所 === 104 === Gene regulation entails a series of nucleic acids modification, including RNA splicing, capping, polyadenosine tailing and RNA editing. ADAR family is one of the widely explored RNA editing enzymes that performs adenosine (A) deamination, with the consequent conversion to inosine(I). Since inosine pairs with cytosine (C), this process is defined as A-to-G editing. For RNA editing in coding sequence, it may result in amino acid alternation, thereby affecting protein function and possibly phenotypes. The coding regions of the actin-binding filamin A and B (Flna and Flnb) genes were previously identified as ADAR2’s targets. The role of filamins function is to stabilize the formation of the cytoskeleton network, which is critical for organism and tissue development, such as in the process of myogenesis. Based on our previous observations that RNA editing of Flna and Flnb underwent significant up-regulation during the muscle fibroblast differentiation, we hypothesized that ADAR editing of Flna and Flnb may contribute to cytoskeleton network during myogenesis. Given that the editing site of Flna and Flnb are located in the dimerization domain, we first investigated dimer formation of Flna and Flnb in C2C12 differentiation. To this end, while Flna and Flnb indeed formed homodimers or heterodimers, there was no difference in interaction between the WT and editing forms. We also suspected that RNA editing would change distribution with actin in a cell, but our immunofluorescence analysis revealed that RNA editing had no significant effect on the colocalization of Flna and Flnb with actin. Interestingly, in an actin polymerization and depolymerization assay, we found that actin exhibits different rates of aggregation and degradation in the presence of WT vs. editing form of Flnb. This observation is in line with the possibility that Flnb editing may be linked to the stabilization of the cytoskeleton that underlies myogenic progression. Together, our results demonstrated the potential role of Flna/Flnb RNA editing event in myogenesis and further support its link to cytoskeleton organization.
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