Scholey Laboratory Research – Molecular Basis of Intracellular Motility and Mitosis

The research of our laboratory is focused on molecular motors, microtubule-based motility and protein machines. Currently we focus on intraflagellar transport and cilium biogenesis, the assembly and function of the mitotic spindle, and the quantitative modeling of mitosis and motility.

Rationale for studying these topics. We study these problems because we want to understand the physical, chemical and engineering principles by which macromolecules organize themselves and function as components of “protein machines” i.e. macromolecular assemblies whose moving parts are motor proteins that generate nm scale displacements and pN scale forces to coordinate virtually every aspect of cell function. These include, for example, the machinery involved in gene expression, the cell division machinery, the motility machinery in the leading edge and muscle sarcomere, the rotary machines of ATP synthesis and the signal transduction machinery. A major challenge for cell biologists is to obtain a quantitative and molecular understanding of the general principles by which such machines function as whole entities and to understand how different protein machines are integrated to produce a living cell.

1. The Machinery of Mitosis. For these studies we focus on early Drosophila embryos, in which biochemistry, antibody microinjection and excellent cytology can be performed in an organism with good genetics and RNA interference. For the past several years our work has focused on understanding how ensembles of MTs and motors cooperate as components of the spindle machinery to drive mitotic movements in Drosophila embryos. We want to know how the motility machinery distributes identical copies of the replicated genome, packaged into chromatids, to each daughter product of every nuclear division.

2. IFT-Motors in C. elegans neurons. Neurons elaborate two MT-filled extensions, dendrites which are specialized for signal reception and axons which are responsible for signal transmission. In C. elegans, sensory cilia on the dendritic endings of neurons serve as subcellular compartments that concentrate sensory receptors and associated signaling molecules. These structures are assembled by motors that deliver cargo such as components of the chemosensory reception machinery and sensory signals, as well as axoneme and ciliary membrane precursors, to their site of incorporation into cilia, in a process called intraflagellar transport (IFT). To determine how IFT- motors cooperate to drive IFT and build these structures, we are using an in vivo time-lapse fluorescence microscopy motility assay that allows us to visualize the movement of GFP-labeled motors and cargo along axons, dendrites and cilia in living animals

3. Mathematical Modeling of Motility events. Ultimately one would like to formulate a set of simplifying principles that can describe the dynamic output of protein machine like the mitotic spindle and the cilium, in terms of the properties of all its parts, and mathematical modeling, combined with molecular and biophysical studies, may provide general rules. Here in the lab, a small group of modelers and cell biologists are working to analyze the mitotic spindle machinery this way.