Elucidating the regulation and function of amyloid-like assemblies

PROJECT SUMMARY
Although amyloids are best understood for their roles in the etiology of numerous human diseases as
pathological protein deposits, amyloid and amyloid-like assemblies can serve critical functions1. To mediate
these functions, some cells have the ability to regulate assembly and clearance of these structures2,3. My
research vision is to delineate the physiological pathways and mechanisms that healthy cells have evolved to
regulate formation, function, and reversibility of amyloids. These studies are motivated by our discovery that in
order to control translation during meiosis, budding yeast regulates assembly of the RNA-binding protein Rim4
into a translational repressor that has several biochemical properties of an amyloid (thus termed amyloid-like)2.
Knowledge gained from these studies will lead to important advances in our understanding of the causes of
neurodegenerative diseases and in time could lead to therapeutic opportunities.
Based on our recent progress studying Rim4 clearance, we now appreciate that yeast cells use multi-
site phosphorylation to abruptly reverse amyloid-like Rim4 into oligomers and monomers at meiosis II onset4. A
major goal of my research program over the next five years is to understand the molecular mechanisms
underlying this remarkable process. Additionally, we will decipher the signals and pathways that trigger the
formation of Rim4 assemblies and we will elucidate how translation is regulated by these structures.
Budding yeast is a powerful experimental system to study these processes. My lab can easily grow
populations of cells that rapidly and synchronously produce, and then clear, amyloid-like Rim4. We have
developed fluorescence-based reporters that allow us to quantify Rim4 assembly and function in single cells
and selection-based reporters that enable robust genetic screens. We have used these tools, in combination
with biochemical approaches, to begin to illuminate the essential factors that govern how these extraordinary
structures are constructed by the cell and the molecular mechanisms underpinning their function.
The MIRA award provided me with the support that I needed to launch and maintain my independent
research program. While we made substantial progress towards our stated goals, this award also gave the
researchers in my lab the freedom to explore fruitful departures from our main focus. For example, we
discovered that yeast cells utilize amyloid-like Rim4 to block the translation of retrotransposon mRNA to protect
the genomic integrity of developing gametes. By making these unexpected discoveries and by developing new
tools, my lab has entered an exciting phase where we are rapidly gaining important insights into how cells
regulate, utilize, and process amyloid-like assemblies. Each discovery serves as a potential lead toward a
therapy for amyloid-related diseases, which are needed because few, if any, effective preventative therapies
are currently available. Columbia University and the Taub Institute for Alzheimer’s and Aging Research
provides the supportive framework and collaborative opportunities to make this possible.

Grant Number: 5R35GM124633-09
NIH Institute/Center: NIH
Principal Investigator: Luke Berchowitz