Mutations in one of the duplicated Survival of Motor Neuron (SMN) genes lead to the progressive loss of motor neurons and subsequent development of Spinal Muscular Atrophy (SMA), a common, usually fatal, pediatric disease. Recent experimental evidence strongly supports the notion that reduced levels of SMN result in a general pre-mRNA splicing defect. The proposed study tests the hypothesis that low levels of SMN result in perturbed pre-mRNA splicing and mRNA transcript levels during motor neuron differentiation, growth, and sprouting, thus reducing the life span of motor neurons as is characteristic for SMA. To test this hypothesis, we plan to use high throughput sequencing technologies to evaluate gene expression and alternative splicing profiles throughout motor neurons differentiation of stem cells derived from normal or SMA patients. These genome-wide surveys will be complemented with experimental verification and computational analyses to gain insights into fluctuations of pre-mRNA splicing networks during the differentiation of stem cells into motor neurons. The results from the proposed experiments will provide expression profiles and an alternative splicing maps that will permit to determine how motor neuron differentiation is perturbed in SMA patients and perhaps other neurological diseases. The verification of the hypothesis will provide new insights into the biological processes that specify longevity of motor neurons and direct future research to identify alternative targets for SMA therapy.
Recent experiments demonstrated that pre-mRNA splicing is required to establish gene expression profiles that dictate the longevity of developing motor neurons. The ability to differentiate human embryonic stem cells into motor neurons in cell culture permits an evaluation of gene expression and alternative pre-mRNA splicing throughout the differentiation process. This unique opportunity is available because the state of California has actively supported research using human embryonic stem cells. The results obtained from this proposal will establish gene expression and alternative splicing maps that link defined developmental events with gene expression and motor neuron differentiation. The resulting signature profiles will enable future studies investigating motor neuron longevity and they will likely identity new molecular targets to battle various motor neuron diseases that have in common premature motor neuron death. As such, the information gained from the proposed experiments would maintain California’s leading status in stem cell research and may provide the intellectual framework for the development of new therapeutic developments in the private sector. An additional benefit to California citizens could be the availability of cutting edge technologies in clinical trials carried out at California's research centers.