The project aims at investigating the contribution of MeCP2 to reprogramming, genomic instability and control of synaptogenesis. Mutations in the MeCP2 gene can cause the Autism Spectrum Disorder (ASD) Rett syndrome (RTT). ASD are complex neurodevelopmental diseases, highly heritable and mainly characterized by deficits in impaired social interaction, and repetitive behavior. The prevalence of ASD has dramatically increased (57%) over the past four years, from 1:150 in 2002 to 1:110 in 2006. Family history and twin studies suggest that, at least in some cases, these disorders share genetic roots, but the degree to which environmental and genetic factors account for individual differences within ASD is currently unknown. A combination of several genetic mutations is likely to play a role in each ASD individual. Mutations and duplication of MeCP2 gene are also observed in other disorders, such as severe neonatal encephalopathy, schizophrenia and X-linked mental retardation. We recently developed an induced pluripotent stem cell (iPSC) system for RTT and showed that MeCP2 is directly involved on the regulation of glutamatergic synapses in human neurons. Also, we demonstrated that MeCP2 is a repressor of L1 retrotransposons, leading to an increase number in somatic mutations. The aims and experiments of this proposal were designed to understand the function of MeCP2 during development. The data generated here will be useful to design novel therapeutic targets for several neurological disorders. The results of this research will have broad implication in the field, with direct consequences for the generation of stem cells free of somatic insertions and the understanding of early stages of synaptic development in human neurons.
Statement of Benefit to California:
Mutations in the MeCP2 gene were linked to several mental disorders, including Rett syndrome (RTT), X-linked mental retardation, severe neonatal encephalopathy, schizophrenia and autism, affecting many Californian children. Because MeCP2 plays an important role in the pathogenesis of multiple disorders, the investigation of MeCP2 function and regulatory pathways in the cell may show promise for developing broad-spectrum therapies. In the absence of a functionally effective cure or early diagnostic tool, the cost of caring for patients with such pediatric diseases is high, in addition to a major personal and family impact since childhood. Our major goal is to understand the regulatory network of MeCP2 molecular interactions in the cells. Our preliminary data strongly suggest that MeCP2 is an important factor for the maintenance of genome stability in stem cells. Moreover, it is also involved in the control of synapses during development. The proposed experiments will bring novel insights on the identification of novel therapeutic targets, potential diagnostics for early detection of several diseases risk, or ability to predict severity of particular symptoms. In addition, the development of this type of validation approach in California will serve as an important proof of principle and stimulate the formation of businesses that seek to develop novel types of therapies in California with consequent economic benefit.
This project examines how MeCP2, a protein involved in epigenetic regulation, plays a role in cellular reprogramming, genetic instability, and synapse formation. Mutations in MeCP2 are known to cause Rett Syndrome and other mental disorders, and the applicant hopes to understand the role of MeCP2 during various processes with the ultimate goal to shed light on the molecular basis of disease. The application has as its specific aims: 1) to determine the contribution of MeCP2 during reprogramming and neural differentiation; 2) to determine the role of L1 retrotransposition during reprogramming and neural differentiation and understand how these processes are influenced by MeCP2; and 3) to determine how MeCP2 regulates synapse formation using Rett patient-derived induced pluripotent stem cells (iPSC).
Significance and Innovation:
- Reviewers were not convinced that the project would have a major impact on potential applications of stem cell research and regenerative medicine, although some reviewers noted that L1 retrotransposition (Aim 2) may impact future use of induced pluripotent stem cells and is thus worth investigating.
- The approaches to identify L1 integration sites and to study the effects of MeCP2 on synaptogenesis were seen as innovative and with a potential to produce useful data.
Feasibility and Experimental Design:
- These studies build on the applicant’s expertise and impressive previous body of work.
- Significant preliminary data were provided, but some data were not well linked to the proposed studies; additionally, some important preliminary studies were described, but the data were not provided.
- Reviewers did not find the preliminary data supporting Aim 1 to be convincing or adequate, since reported changes in reprogramming frequency were only modest, and the chosen marker is not a reliable indicator of pluripotency.
- Reviewers agreed that the three aims were poorly organized and did not flow logically from one to another.
- Reviewers found the proposal hard to follow and not well written.
- Reviewers were unclear on the rationale for studying MeCP2 both in reprogramming and in synaptogenesis, rather than focusing on one of these two distinct roles.
Principal Investigator (PI) and Research Team:
- Reviewers praised the credentials of the PI as an outstanding young and innovative scientist with a strong track record and publications in high impact journals. The track record of the PI was seen as a major strength of the application.
- Strong collaborators with appropriate expertise for the proposed studies are also leaders in the field.
- Reviewers expressed concern about substantial overlap of the proposal with work funded by a current NIH award.
Responsiveness to the RFA:
- The application is responsive to the RFA, using human patient-derived iPSC to conduct molecular mechanistic studies.