Date of Award
Doctor of Philosophy (PhD)
MacMARCKS is a second member of the MARCKS family of PKC substrates which integrate signal transduction events with changes to the actin cytoskeleton. Work presented here demonstrates diverse roles for MacMARCKS ranging from neural secretion to neural development. Chapters 3 and 4 describe the role of MacMARCKS in neural secretion. MacMARCKS is phosphorylated in a stimulus-dependent manner in rat brain synaptosomes and PC 12 cells. It is localized to cell bodies and neurite tips of PC12 cells as well as being present on synaptic vesicles. A dominant-negative mutation in the MacMARCKS effector domain which abolishes PKC-dependent phosphorylation is associated with changes in cellular morphology and blocks agonist evoked exocytosis in PC 12 cells. Characterization of the MacMARCKS promoter is presented in Chapter 5. The LPS response elements of the MacMARCKS promoter are localized to a region 113 bp upstream of the transcriptional start site; this region contains multiple SP-l sites. Regulation of MacMARCKS induction by LPS appears to be by posttranscriptional mechanisms. Chapters 6 and 7 presents evidence that MacMARCKS is involved in mouse neural development. Endogenous MacMARCKS expression is neural specific early during embryonic development but is expressed in other tissues later on. In adult animals, MacMARCKS expression localizes to specific regions of the adult brain. Transgenic mice carrying 4 kb or 1.7 kb of MacMARCKS upstream flanking regions directed neural-specific expression of the -galactosidase reporter gene in a developmentally regulated manner. Targeted deletion of the MacMARCKS gene in mouse embryos leads a failure of cranial neural tube closure, resulting in exencephaly. MacMARCKS null mice are born anencephalic and die soon after birth. The work presented in this thesis demonstrates that MacMARCKS is essential for processes associated with signal transduction events leading to reorganization of the actin cytoskeleton.
Chang, Sandy, "MacMARCKS and the Protein Kinase C Signal Transduction Pathway: Role in Neural Secretion and Neural Development" (1996). Student Theses and Dissertations. 444.