Michael Chumley - US grants

DESCRIPTION (provided by applicant): The high-affinity Trk and low-affinity p75NTR receptors play critical roles in the growth, differentiation, and survival or neurons and glial cells. Numerous reports support a cross talk between these neurotrophin signaling pathways that is likely critical in regulation of growth, differentiation, and survival. Furthermore, this interplay of signaling pathways likely requires a high degree of organization for optimal regulation. Therefore, the long-term objectives of this research are to define the molecular mechanisms that regulate cross talk between Trk A and p75NTR neurotrophin receptors and the functional significance of this cross talk in neuronal populations. Data presented herein strongly suggest that the Trk A and p75NTR pathways converge at the interaction of PI 3-kinase and acid sphingomyelinase (SMase). However, it remains unknown how PI 3-kinase interacts with acid SMase, Thus, the Specific Aims of this proposal are: 1) to determine the minimal binding domain within p85 that interacts with acid SMase an 2) to assess the role of the YXXM, NPXY, and proline-rich sequences of acid SMase in the interaction with p85.

PROJECT SUMMARY/ABSTRACT Uncontrolled oxidative stress contributes to the development of neurodegenerative disease. This project focuses on the synthesis and analysis of four new groups of molecules based on a pyridol- containing N-heterocyclic amine parent molecule previously and successfully developed by the PI. The investigators demonstrated that this parent small molecule exhibits significant antioxidant reactivity in biological assays, is capable of crossing the blood brain barrier, and reduces beta-amyloid plaques in animal models of neurodegenerative disease. The investigators will use a rational design strategy to create the libraries and as such expect the new molecules to exhibit enhanced antioxidant activity (C.2- C.3), metabolic stability (C.4), and blood brain barrier permeability (C.5) compared to the parent molecule. The results from our first past screen will be used for further structural changes and studies. The new molecules are expected to provide potent antioxidant activity through structural modifications to the parent molecule, including (1) addition of pyridol groups, (2) changes in the base ring structure to target a range of toxic metal ions, (3) fatty acids, and (4) chemical groups inspired by nature?s own antioxidant store. We will study the first 13 new, enhanced antioxidant molecules using assays designed to understand pathways of chemical reactivity and cell culture work to assess toxicity and to quantify the ability of each new molecule to protect cells from four different models of oxidative stress. Molecules showing potent antioxidant activity will then be screened for metabolic stability and blood brain barrier permeability. The results from these studies will be used to produce hybrids of Groups 1 -2 with Groups 3-4, which will undergo similar screens to find optimized lead compounds suitable for further in vivo studies. This approach will identify the path(s) of protection each strategy of antioxidant enhancement provides and identify lead molecules to be explored further and proceed to future work involving animal toxicology, clearance, and activity assessment. Altogether, a comparative approach that uses data from chemical assays and biological studies will allow the investigators to identify molecules and moieties that provide the characteristics needed to serve as a therapeutic for neurodegenerative disorders arising from oxidative stress. This proposal takes a unique approach to targeting neurodegenerative disease by using synthetic chemistry to combine different reactive building-blocks into small molecules designed to have activity through targeting molecular features of neurodegeneration in a manner that is greater than the sum of the individual parts.