PROJECT SUMMARY/ABSTRACT
Transport of nucleic acids and proteins from the nucleus to the cytoplasm is essential for nearly all cellular
processes, and when mis-regulated, is associated with diseases, tumor formation/growth, and cancer
progression. Canonically, this indispensable process has been thought to occur exclusively via Nuclear
Pore Complexes, which span the nuclear envelope’s double membranes and provide a critical regulatory
step in what exits (and enters) the nucleus. Recently, Nuclear Envelope (NE-) budding was shown to
provide an alternative pathway for nuclear exit, particularly for large ribonucleoprotein (RNP) complexes
that would otherwise need to unfold/remodel to fit through the pores. In this pathway, large
macromolecule complexes are encapsulated by the inner nuclear membrane, cross the perinuclear
space, fuse with the outer nuclear membrane, and are released into the cytoplasm, a mechanism
strikingly similar to herpesvirus nuclear egress. Thus, NE-budding elegantly allows for large RNP
complexes to exit the nucleus together and be delivered as a package for specific cellular functions.
Despite its clear biological importance and clinical relevance, very little is yet known about the regulatory
or structural machineries that allow NE-budding to occur in any system. Recently, we found that the
Wiskott Aldrich Syndrome family actin nucleation protein, WASH, its four subunit regulatory complex
(SHRC), and Arp2/3 are necessary for NE-budding. Using WASH/SHRC as a new entry point, in tandem
with strategies to discover novel genes/proteins involved in this process, our long-term goal is to
understand the molecular and cellular mechanics that govern NE-budding. The specific aims of this
proposal are to determine the mechanism(s) of WASH/SHRC function in NE-budding, and to
identify/analyze the infrastructural components/machineries governing the dynamic NE-budding process
using a combination of genetic, biochemical, cell biological, time-lapse live imaging, and super-
resolution/EM microscopy approaches. Drosophila provides an excellent, genetically amenable,
organism for studying this conserved process due to its amenability for imaging and the wealth of cutting
edge cell/molecular techniques and reagents. The information gathered in these studies will help to
elucidate the mechanisms governing this exciting new nuclear export pathway in normal development or
when mis-regulated in disease conditions, and may inform the study of herpesvirus nuclear egress as
well.