Suppression of the Methyl-CpG Binding Protein 2, MeCP2, Inhibits Neurite Extension in PC12 Cells
Type of Culminating Activity
Master of Science in Biology
Julia Thom Oxford
Regulation of gene expression is critical to the proper development of neuronal cells. The methyl-CpG binding protein 2 (MeCP2), operates as a transcriptional repressor by facilitating histone deacetylation and DNA methylation-dependent transcriptional silencing. Using an in vitro neuronal model, consisting of PC 12 cells, the present thesis study examined the importance of MeCP2 in regulating neurite formation. Following the induction of neuronal differentiation, a time-dependent increase in MeCP2 expression that reached a maximum level at 24 hours, occurred at both the transcriptional and translational level. In addition, a marked inhibition of neurite extension was observed following treatment of PC12 cells with an antisense morpholino oligomer (MeCP2 AS). The removal of MeCP2 AS allowed for complete recovery of neurite extension. Morphometric analysis of neurite length revealed that in the presence of MeCP2 AS, the neurite projections of the PC12 cells remained similar over time to the processes of cells treated with NGF alone for 24 hours. However, the addition of MeCP2 AS to previously differentiated cells had no effect on the stability and maintenance of the neurite processes. Furthermore, PC12 cells treated with MeCP2 AS exhibited inappropriate cleavage of full-length tau, a microtubule associated protein essential in the proper formation of neurite extensions. Upon the removal of MeCP2 AS the cells no longer exhibited tau degradation. The proteolytic processing of tau was attributed to caspase-3 activity. PC12 cells in the presence of MeCP2 AS and treated with a caspase-3 inhibitor regained partial neurite extension. Taken collectively, the results indicate that MeCP2 expression plays an important role in the neurite extension of PC12 cells and is a fundamental component in the regulation of mediators, such as caspase-3, that effect tau degradation and stability.
Cusack, Sorcha M., "Suppression of the Methyl-CpG Binding Protein 2, MeCP2, Inhibits Neurite Extension in PC12 Cells" (2003). Boise State University Theses and Dissertations. 658.