Susana R. Neves, Ph.D. - US grants

DESCRIPTION (provided by applicant) The Mitogen Activated Protein (MAP) Kinase has been implicated in the regulation of several essential cellular processes such as proliferation, differentiation and apoptosis. The regulation of this important pathway has been the focus of many studies. In PC12 cells the sustained activation of MAPK leads to differentiation while the transient activation leads to proliferation. It remains unclear the mechanism underlying the difference in magnitude of activation of MAPK 1,2 but it has been hypothesized that it involves regulatory contributions from the cAMP signaling cascade. Here we present a novel regulatory feedback loop that may be able to promote the sustained activation of MAPK 1,2 in response to growth factors. This loop involves the differential expression of the cyclic nucleotide phosphodiesterase PDE4D long and short isoforms. Depending on the predominant ratios of long to short PDE4D isoforms found in PC12 cells, the activation of MAPK can be sustained or transient. We propose the use of novel computational modeling techniques along with experimental data to characterize this regulatory loop and understand its significance in the regulation of the cellular fate of PC12 cells.

DESCRIPTION (provided by applicant): This project seeks to address the mechanisms underlying tissue integrity. We view tissue as networks of interacting cells and matrices. We hypothesize that tissue integrity results from the integration of information that arises from the dynamic interactions between the different cell types and the matrices that bind these cells together. To test this hypothesis we will focus on the kidney glomerular filtration barrier. In this system we predict that continuous information flow between a three-node loop consisting of podocytes cells, glomerular basement membrane and endothelial cells results in integrating the three entities into a single cohesive functional structure: the filtration barrier. Such information is both chemical (secreted autocrine /paracrine factors and cell/cell and cell/matrix contacts) and physical (forces arising from cell/cell and cell/matrix contacts). The information from physical and chemical sources is seamlessly integrated by intracellular signaling networks in the podocytes and endothelial cells to evoke responses that dynamically sustain the three-node loop, resulting in tissue integrity and functionality. To test these ideas we will merge 3D- computational models, nano-to-micro scale 3D fabrication and nanopatterning coupled to microfluidic devices to reconstitute a filtration barrier within the engineered device. We will use live cell imaging of signaling interactions to measure the dynamics of information flow arising from interactions between components of the reassembled tissue that give rise to the glomerular filtration barrier within the device. It is anticipated that these studies will allow us to identify general design principles to assemble functional tissues that can aid in understanding disease processes and for screening for new drugs. PUBLIC HEALTH RELEVANCE: The goal of this project is to understand how cells come together to form tissues. We will use the filtration barrier of the kidney cortex as our model system. We will use a combination of mathematical models and engineering approaches to develop a 3D tissue assembly.