Formation and function of lamellipodial morphology in 3D microenvironments

University Of Minnesota, Minneapolis MN

Investigators

Abstract

Project Summary Dendritic cells are the sentinels of the immune system. They patrol the body looking for antigens and then migrate to a lymph node to communicate what they found to T cells and other cells of the adaptive immune system. These professional migrators and searchers are a critical component of human immunity, and their migration is targeted or hijacked by multiple pathogens including some pox and herpes viruses, tuberculosis, and anthrax. Since dendritic cells can activate cytotoxic T cells to attack cancer cells, their migration also plays a role in cancer immunotherapy strategies. Many cells, including dendritic cells, migrate by extending lamellipodia. Lamellipodia are thin, planar protrusions that have been extensively studied for cells migrating on 2D surfaces, such as glass coverslips. Dendritic cells use lamellipodia to find a path through crowded 3D environments and to enter lym- phatic vessels. Lamellipodia and the actin network that composes them have been studied for decades. How- ever, most molecularly detailed models of lamellipodia regulation and function were derived from studying cells on 2D surfaces, so we still do not know how cells initiate and extend lamellipodia in 3D environments. In this project, we will investigate how actin nucleators organize to generate sheet-like lamellipodial morphologies in the absence of a surface to guide their generation, as well as how actin nucleators organize to direct the exten- sion of lamellipodia within crowded 3D environments. As a model of dendritic cell migration through peripheral tissues, we will study migration though 3D fibrous collagen matrices. Widely available microscopic techniques, such as confocal microscopy, cannot image cells in 3D collagen with the spatial and temporal resolution required to measure the organization of actin nucleators in lamellipodia. However, recently developed techniques, such as light-sheet microscopy, are just beginning to be able to do so. Since light-sheet microscopes can produce massive datasets, interpreting and even simply visualizing such large amounts of data requires sophisticated computing workflows. We will develop the needed computational workflows as we investigate lamellipodia form and function in 3D environments.