Loss of motor neuron function causes reduction of lifespan: 1). Selective inhibition of motor neuron specification gene (HB or Nkx6.1) expression results in lethality at early developmental stages in the knockout mouse models; 2). Selective degeneration of matured motor neurons by overexpression of mutant SOD1 gene in the transgenic mouse (rat) models causes loss of motor function mimicking human amyotrophic lateral sclerosis (ALS). The long-term objective of this research application is to study the role of HB-9 expression in motor neuron regeneration and in extension of lifespan in the ALS-like transgenic mouse model. The hypothesis of the current research proposal is that the induction of HB-9 gene expression may induce motor neuron specification from neural precursor (stem) cells in vivo in a mouse model. The newly regenerated motor neurons may functionally replace the degenerated motor neurons and therefore may extend the lifespan of ALS-like transgenic mice. The following specific aims will be performed to test the hypothesis:
Specific Aim 1 : To generate transgenic mouse model for induction of HB-9 expression in neural precursor cells. Specifically, we will use the well-established Tet-on/TRE systems to define the induction conditions for expression of liB-9 in neural precursor cells of the bi-transgenic mice containing both pNestinrtTA and TRE-HB-9 transgenes.
Specific Aim 2 : To determine if the expression of HB-9 in neural precursor cells can promote motor neuron specification and regeneration. Specifically, we will use specific motor neuron markers to analyze HB-9-mediated motor neuron specification and differentiation (regeneration) in the bi-transgenic mouse spinal cord induced by Dox. The future research directions will focus on the tri-transgenic mouse model of motor neuron specification and regeneration on the improvement of motor function and the extension of lifespan in the ALS-like transgenic mouse system.
