2005 — 2006 |
Lu, Qun |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Delta-Catenin Cleavage by Presenilin and Synaptic Remodeling @ East Carolina University
DESCRIPTION (provided by applicant): Mutations in presenilins are closely linked to familial Alzheimer's Disease (AD). It is well established that presenilin expression is essential for "y-secretase" processing of many proteins of diverse functions, including the amyloid precursor protein and cell adhesion protein cadherins. This laboratory cloned a human delta-catenin that associates with cadherins and glutamate receptors of synaptic junction, and it redistributes upon glutamate stimulation. Our recent studies found that delta-catenin not only binds directly to presenilin-1 (PS-1), but it is also cleaved by a S-1/y-secretase-dependent activity. This RO3 small grant application proposes a research project to test the hypothesis that delta-catenin cleavage products interact with glutamate receptor complexes and facilitate postsynaptic responses to excitatory stimuli, such as amyloid beta (AB) peptides and N-methyl-D-aspartate, which increase neuronal vulnerability to excitotoxicity in AD. To test this hypothesis, Specific Aim 1 will employ PC12 cells stably expressing a tetracycline-inducible delta-catenin to determine the amino acid sequence of delta-catenin cleavage site generated by PS-1/y-secretase dependent activity. Delta-Catenin cleavage sequence will be determined using protein sequencing, site-directed mutagenesis, and cDNA transfection. Specific Aim 2 will determine the distribution and effects of delta-catenin proteolytic fragments in the postsynaptic responses to excitatory stimuli, such as AB peptides and NMDA. Protein co-immunoprecipitation and Western Blotting will determine the interaction of delta-catenin fragments with glutamate receptor complexes. Time-lapse fluorescent microscopic imaging will determine their redistribution upon AB and NMDA stimulation. In addition, Fura-2 ratiometric imaging will be used to determine the effects of delta-catenin fragments on the alterations of intracellular calcium level, a central component in the excitotoxic neuronal death cascade. This RO3 small grant project will lead to new insights into mechanisms of synaptic plasticity regulated by PS-1 interaction with delta-catenin. It will also lay the foundation for future R01 investigation of the roles of delta-catenin proteolytic fragments in AD pathogenesis.
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0.904 |
2006 — 2010 |
Lu, Qun |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Delta-Catenin and Cell-Cell Adhesion in Prostate Cancer @ East Carolina University
[unreadable] DESCRIPTION (provided by applicant): Prostate cancer (CaP) is the most common malignancy in men in US and the second leading cause of cancer mortality. To reduce the significant morbidity and mortality, new strategies for CaP prevention and treatment depend on the determination of specific molecular mechanisms involved in this disease. ?-Catenin is a unique armadillo (ARM) domain-containing protein in that it is neural specific and primarily expresses in the brain. However, ?-catenin expression increases in prostatic adenocarcinomas, redistributes E-cadherin/p120ctn from the cell-cell junction, and promotes CaP cell growth and invasion. To investigate this largely unexplored area of neuronal catenin gene expression in peripheral tissues of cancers, the overall goal of this project is to test the hypothesis that ?-catenin promotes CaP formation and progression by interacting with multiple cellular machineries, including cell-cell and cell-matrix adhesion, cell growth/survival, and invasion. There are three specific aims in this proposal. Specific Aim 1 will determine how ?-catenin promotes cell growth/survival and motility in response to the hepatocyte growth factor and/or androgen using CWR22 tumor xenografts and their derived cell lines. We will broadly screen and profile the ?-catenin induced alteration of signaling molecules by array technology. These studies will identify cancer specific pathways that ?-catenin is involved in and will investigate their interactions with ?-catenin using protein co-immunoprecipitation and yeast two-hybrid analyses. Specific Aim 2 will determine how ?-catenin interacts with Rho family small GTPases to disrupt adherens junction and promote CaP cell growth/survival and invasion. We will first identify the ?-catenin sequence responsible for this action. Then, the analyses of ?-catenin RNAi or its mutants that are defective in Rac-1 or E-cadherin binding will determine the interactions between GTP-Rac-1/IQGAP-1 and E-cadherin/p120ctn pathways to reveal possible differential modulations on cell-cell adhesion and cell growth/survival and invasion. We will also determine the cytoplasmic accumulation and nuclear signaling of ?-catenin that is released from E-cadherin complexes by IQGAP-1. Specific Aim 3 will apply Y311, a unique (dePhospho-specific) monoclonal antibody, and site-directed mutagenesis to determine how ?-catenin modifications occur and what are their roles in CaP. We will also investigate ?-catenin proteolytic fragments and their potentials as DNA binding proteins and nuclear signaling for gene expression. Finally, we will generate transgenic mice displaying prostate tissue specific ?-catenin expression to approach these questions at the animal level. These studies will place ?-catenin into the broad context of growth factor and kinase signaling machineries relevant to CaP. Understanding the posttranslational modifications that control ?-catenin functions will unravel mechanisms by which ?-catenin modulates gene expression and promotes CaP in vivo. [unreadable] [unreadable]
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0.904 |
2012 — 2014 |
Lu, Qun |
R15Activity Code Description: Supports small-scale research projects at educational institutions that provide baccalaureate or advanced degrees for a significant number of the Nation’s research scientists but that have not been major recipients of NIH support. The goals of the program are to (1) support meritorious research, (2) expose students to research, and (3) strengthen the research environment of the institution. Awards provide limited Direct Costs, plus applicable F&A costs, for periods not to exceed 36 months. This activity code uses multi-year funding authority; however, OER approval is NOT needed prior to an IC using this activity code. |
Rho Gtpases and Neuroprotection Model in Cancer Therapy @ East Carolina University
DESCRIPTION (provided by applicant): Widely-used chemotherapy drugs, such as platinum, exhibit a high level of treatment-associated toxicity including neurotoxicity which is often dose limiting and can be devastating to a patient's quality of life long after the therapy ends. We have identified that suppression of RhoA signaling by p160ROCK/Rho kinase inhibitor Y-27632, which inhibits cancer cell motility and invasion, can reverse anti-cancer drug-induced neurodegeneration in the novel cisplatin-induced peripheral neuropathy (CIPN) mouse model developed in this laboratory. Few molecular pathways demonstrate this unique capacity of inhibiting cancer cell expansion while exhibiting neuroprotective effects. Establishing the mechanisms underlying this pathway to increase cancer-attacking efficacy will have significant impact since both platinum and Y-27632 have proven to be clinically safe and can expand to many anti-cancer drug applications. In this R15 AREA project, we propose to use both normal and tumor-bearing mice to test the hypothesis that suppression of Rho GTPase signaling coupled with chemotherapy drugs provides an effective strategy for attacking cancer while protecting neurons. Specific aim 1 will investigate two potential molecular mechanisms (ERM protein activation and redistribution to actin to activate Fas receptor/CD95 and SRF-dependent gene transcription) by which suppression of Rho GTPase signaling pathway protects neurons from cisplatin-induced neurotoxicity. Specific aim 2 will apply innovative small molecule Rac1/Cdc42 activator/inhibitor reservoirs to investigate whether crosstalks among the subclasses of Rho GTPases enhance the RhoA suppression-mediated inhibition of CIPN. Specific aim 3 will investigate RhoA pathway inhibition and neuroprotection in cisplatin anti-cancer therapy in murine models of primary and metastatic lung carcinoma. We will determine whether cisplatin and Y-27632 (or RhoA/SRF-dependent transcription inhibitor CCG-1423) combinations enhance anti-cancer efficacy while reducing CIPN (measured by improving sural nerve conduction and touch sensation) in immunocompetent mice inoculated with syngeneic Lewis Lung carcinoma cells. These studies, engaging the continuous graduate and undergraduate student research in this laboratory, will establish Rho GTPase signaling as an innovative drug target for combined neuroprotection and cancer inhibition in clinical cancer therapy. PUBLIC HEALTH RELEVANCE: Widely-used chemotherapy drugs, such as platinum, exhibit a high level of treatment-associated toxicity including neurotoxicity which is often dose limiting and can be devastating to a patient's quality of life long after the therapy ends. This project is a preclinical study to determine whether suppression of Rho GTPase signaling coupled with chemotherapy drugs provides an effective strategy for attacking cancer while protecting neurons.
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0.904 |