Single molecule dissection of Arp2/3 complex regulators in living cells

Arp2/3 complex-dependent F-actin assembly is the main driver of pushing forces in cells, facilitating a wide range of essential functions such as lamellipodial motility, endocytosis, trafficking of diverse organelles, DNA repair, and mitotic spindle positioning.

Mis-regulated Arp2/3-actin control pathways drive diseases such as metastatic cancer, immune and neurological dysfunction, but we have yet to understand how the underlying proteins function at the cellular level. Precise treatments will require building a holistic understanding that bridges the cellular-scale network dynamics and the biochemical activities of key components.

We aim to mechanistically address key knowledge gaps of Arp2/3-network regulation by bridging discrete molecular activities of Arp2/3 complex regulators to their cellular-scale dynamics. We employ a broad range of expertise from genetics and cellular approaches to quantitative single molecule -based biophysical methodologies.

Molecular mechanisms of direct cell-cell communication

Cell-to-cell communication is critical to human physiology and diseases. In recent decades, the membrane enclosed, thin tube structures that directly connect cells, known as tunneling nanotubes (TNT), have gained recognition as an important mechanism of intercellular communication.

Linear actin filament bundles are responsible the formation and function of TNTs. Various cellular materials can be transferred through these conduits, including protein aggregates, viruses, small molecules, ions and organelles. Consequently, TNTs contribute to multitude of human pathology propagations. Cancer cells can readily form nanotubes to redistribute chemotherapeutics and steal mitochondria from immune cells to evade treatments. Currently, molecular pathways and components that drive the formation and function of TNT are largely unknown.

Our central hypothesis is that TNT linear actin is built through a specific set of actin binding proteins to facilitate actin-based content transfer between cells. We take advantage of our quantitative single molecule localization microscopy, combined with cell and molecular biology methods to over-come the limitations of these extremely thin structures, and to understand how actin within TNTs is spatiotemporally controlled to fulfill roles of both material transport within TNTs and sustain TNT structures.