Collaborative Regulation of Translational Targets by the ARF and NF1 Tumor Suppressors
Abstract
Plexiform neurofibromas (PNs) arising from Schwann cells are a hallmark manifestation of neurofibromatosis type 1 (NF1). Approximately 15% of PNs will transform into very aggressive late-stage malignant peripheral nerve sheath tumors (MPNSTs), which are a leading mortality in NF1 patients. A gene was mapped to individuals affected by NF1. This gene, termed Nf1, carried an inheritable mutation that appeared to predispose these individuals to NF1. Because of the association between NF1 and tumor development, Nf1 has been classified as a tumor suppressor gene. The product of the Nf1 gene is the neurofibromin protein. Work has shown that the normal role of neurofibromin is to prevent hyperactivation of the mTOR growth-signaling pathway. Loss of neurofibromin in NF1 individuals leads to uncontrolled mTOR activities. This in turn directs Schwann cells to initially grow (get larger) and proliferate (divide). However, Nf1-deficient cells rapidly induce the ARF tumor suppressor, which prevents further growth and proliferation. In this manner, neurofibromin and ARF work together to prevent Schwann cell transformation and progression to MPNSTs. While much of the NF1 scientific community is focused on the mTOR pathway as a sole manifestation of NF1, our group has chosen to study the mechanisms underlying the progression from PN to MPNSTs through the concomitant loss of both the Nf1 and Arf tumor suppressors. We provide preliminary evidence that this progression involves an increase in mRNA translation. Once bound to an mRNA, the ribosome translates the message into protein. One could imagine that, if mRNAs are loaded onto ribosomes faster, more protein will be produced. Likewise, an mRNA that is loaded more slowly, or not at all, would result in less protein synthesis. In this manner, regulation of which mRNAs are being translated becomes integral in determining the protein landscape of the cell and, ultimately, what processes the cell performs. The goal of this proposal is to identify the mRNAs whose translation is affected by the loss of Nf1 and Arf and to characterize the mechanism behind their altered translation. To achieve this goal, we are proposing two complimentary approaches. The first involves a novel screen, one that has never been performed in the neurofibromatosis field, although our laboratory has already utilized this technique in other cell types. Our screen will serve to identify mRNAs that are either loaded faster, slower, or not at all on ribosomes in Nf1/Arf-deficient Schwann cells. The second approach involves understanding how these mRNAs are loaded differently by identifying proteins that uniquely interact with these mRNA. We hypothesize that specific proteins are responsible for binding to these mRNAs and either placing them on the ribosome or preventing them from loading onto the ribosome. If we can identify these translation regulators, we may discover why PNs progress to MPNST following loss of Nf1 and Arf tumor suppressor genes. Our methodology is novel for this field and brings together protein biochemistry, mouse genetics, and cell biology disciplines. My laboratory is well versed in all of the proposed techniques and is poised to generate data at an accelerated rate for this 2-year study. It is my hope that this proposal will launch other studies into PN to MPNST progression and provide us with the means to move our ideas forward into a clinical setting. The results generated by this study will open doors to new therapeutic targets and approaches in treating neurofibromatosis and present others in the field with a roadmap for intertwining scientific disciplines into novel strategies in NF1 disease research.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 05, 2021
- Source ID
- W81XWH2110391
Entities
People
- Jason D Weber
Organizations
- United States Army
- Washington University in St. Louis