Shoc2 scaffold mediates motitlity signals of the ERK 1/2 pathway

Background: The ERK1/2-MAPK signaling pathway plays an important role in all of the cellular processes that a cancer cell must exploit on the path to malignancy. This signaling cascade is a fundamental cellular process that orchestrates diverse, sometimes-opposing, biological outcomes, and the mechanisms that ensure signal specificity are complex. Scaffold proteins are key players that deliver signaling specificity, regulate accessibility to substrates and, therefore, determine the biological outputs of the ERK1/2 pathway. Objective/hypothesis: The objective of this proposal is to determine the mechanisms by which the critical Shoc2 scaffold protein orchestrates ERK1/2 signaling to direct cell motility and invasion of breast cancer cells. We hypothesize that the Shoc2 module transmits signals of the ERK1/2 pathway to the proteins regulating cell motility, thus contributing to the breast cancer cell migration and metastasis. Specific aims: 1) to define the role of endosomal compartmentalization of the Shoc2 scaffold complex for cell motility, 2) to dissect the molecular mechanisms by which HUWE1 regulates Shoc2-transmitted motility signals in breast cancers, and 3) to determine how Shoc2-mediated signaling regulates cell adhesion and motility and in breast cancer. Study design: We will use complementary biochemical and state-of-the-art imaging approaches to determine distribution of the Shoc2 scaffold complexes in migratory cells. We next will conduct the studies using combination of protein biochemistry with functional analysis of ERK1/2 signaling outcomes. The role of Shoc2 and Raf-1 ubiquitination by HUWE1 in a mechanism to monitor duration/amplitude of ERK1/2 cell motility signals in breast cancers will be determined. Finally, we will establish the functional consequences of Shoc2 depletion on cell adhesion using cell-based functional assays and define molecular determinants of Shoc2-mediated ERK1/2 signals to cell adhesion. Cancer relevance: The proposed research will test the hypothesis that the positive regulator of the ERK1/2 pathway - scaffold protein Shoc2 plays a significant role in breast cancer progression and invasiveness. Completion of the proposed studies will contribute to our understanding of the mechanisms underlying cell motility. The results will potentially lead to the development of novel therapeutic strategies for controlling invasive mammary tumor cells.