A central issue for the treatment of multiple sclerosis (MS) is how to promote the survival of cells that reside in the CNS since the progressive nature of the disease results in axonal damage, neuronal cell loss, oligodendrocyte cell death, and permanent demyelination. AKT serine-threonine kinase family members are important regulators of cell growth, proliferation, and cell survival. AKT3, the major form expressed in the brain, is found in neurons and oligodendrocytes, but is also expressed in the immune system. We determined that AKT3-/- mice sensitized to develop myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), an animal model with aspects of MS, resulted in more severe disease than in wildtype (WT) mice. Pathological analysis showed that AKT3-/- mice had increased prevalence of axonal damage and demyelination than WT mice with chronic disease. Bone marrow transfer experiments indicated that cells within both the immune system and the CNS contributed to this effect. The objective of this proposal is to define the cells contributing to the more severe phenotype observed in mice lacking AKT3. To this end, germline transmission of AKT3-floxed mice will be generated. Mice will then be crossed with FLP mice to delete the FRT site and generate AKT3floxed conditional mice. Then each -Cre strain will be crossed with the AKT3floxed conditional mice to generate F1. AKT3 conditional knock-out (KO) mice with deletion of AKT3 in select immune cells, in neurons, and in oligodendrocytes will be generated. These mice will be evaluated and once assured that the conditional KO is obtained we will apply for additional funding to examine these mice during MOG-induced EAE. These studies will expand our understanding of the contribution of AKT3 to the function of immunocompetent cells versus AKT3's role within the CNS. Our long term goal is to characterize the role of AKT3 in the CNS and in immune cells so that therapeutic approaches might focus on signaling molecules affected by the AKT3 pathway, and provide protection against CNS inflammation and tissue destruction found in MS.
The ability to achieve successful myelination is a priority for movement and higher brain function. To obtain successful remyelination following injury would positively impact upon the public health of individuals of all ages and dramatically improve the quality of their lives. Our ongoing studies demonstrate that deletion of AKT3 exacerbates demyelination during MOG-induced EAE; and Akt3-/- mice have a more severe and chronic disease course. This proposal will generate and study AKT3 conditional knockout to further explore the role of AKT3 in the CNS. This study will provide new insights into the role of AKT3 in inflammation and demyelination in mouse models of human demyelinating diseases such as multiple sclerosis.
