Friday, May 3, 2024
5/3/2024
Project Summary/Abstract This is an administrative supplement to support the career development and training of a deserving underrepresented applicant, Damian Lozano, as he completes his dissertation research. The parent R01 involves studying mechanisms which contribute to outcomes after ischemic stroke, the leading cause of long- term disability in the U.S. Neural stem cells (NSCs) have demonstrated therapeutic benefit in stroke recovery, however mechanisms are still being elucidated. Our data show NSC function is influenced by low-density lipoprotein receptor-related protein (LRP1), a multifunctional modulator of cell signaling. We discovered that in NSCs, LRP1 enables NSC migration to ischemic lesions by regulating expression of the chemokine receptor CXCR4. Loss of LRP1 in NSCs also causes reduced lesion sizes. The parent R01 tests the overall hypothesis that LRP1 promotes NSC migration toward ischemic lesions through CXCR4 regulation, yet also limits the endogenous NSC-neuroprotective response. A key question in the parent R01 involves understanding which LRP1 subdomains are responsible for discrete phenotypes observed in our mouse model with adult NSC-specific knockout of LRP1. LRP1 is characterized by an external ligand-binding domain, LRP1a, which is non-covalently associated with a transmembrane domain, LRP1ß. The LRP1ß domain is essential for the trafficking and recycling of LRP1, assembly of signaling scaffolds, and also can be cleaved to allow the c-terminus to transport to the nucleus and regulate transcription. The goal of this supplement is to test which subdomains of LRP1ß regulate CXCR4 expression and stroke recovery. Given that we have observed reduced CXCR4 mRNA expression in vivo after LRP1 knockout, we hypothesize that the c-terminal cleavage of LRP1 is responsible for transcriptional regulation that mediates CXCR4 expression and enhanced stroke recovery. To test this hypothesis, the mentee will utilize our Nestin-driven, tamoxifen inducible LRP1 knockout mouse model and lentiviral expression constructs that rescue portions of LRP1ß both in vitro and in vivo. Aim 1 will test the hypothesis that the c-terminal domain of LRP1 restores expression of CXCR4 in NSCs without LRP1. Aim 2 will elucidate the influence of the c-terminal domain of LRP1 on stroke recovery in mice with NSC-specific knockout of LRP1. In addition, this supplement proposes a rigorous training and career development regime meant to enhance the future career prospects of the mentee in biological research, whose career goal is to ultimately run an independent research and teaching program in biomedical sciences. Altogether, this supplement will elucidate specific roles of LRP1 subdomains on NSC physiology and stroke recovery, enabling more targeted approaches to stroke therapy while promoting the inclusion and training of an exemplary candidate in neuroscience.
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