What are ly6 proteins and what do they do?

The ly6 proteins are a novel family of regulatory proteins conserved among multiple species (humans, mice, rats, fruit flies, zebrafish, and nematodes) that share significant structural homology to alpha neurotoxins commonly found in snakes, such as bungarotoxin. These toxins are known to target a variety of ionotropic receptors to inhibit or potentiate their function away from baseline levels, resulting in negative consequences to the organism. This begs the question-- what are the ly6 proteins doing in us if they look like toxins but (thankfully!) don't behave as such?

Only a handful of ly6 proteins have been well-characterized, with work showing that these proteins appear to be involved in a variety of cellular processes including regulation of receptor trafficking (such as nicotinic acetylcholine receptors). Putting it all together, our lab is interested in the following questions:

  • What are the protein targets of ly6-mediated regulation?
  • How do ly6 proteins affect the function, expression, and/or cellular location of their protein targets?

We use techniques from structural biology, biochemistry, cell biology, and molecular biology in order to answer these questions!

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Ongoing research projects:

Regulation of AMPA receptor function by ly6g6d and lypd2

The inside of a cell is an incredibly dynamic place, with various receptors and proteins being constantly shuttled to and from the plasma membrane. A critical aspect of receptor function is for the receptor to be in the right place at the right time-- examples of this include significant changes in the types of receptors found in the synaptic membrane following neuronal stimulation or inhibition. The regulation of where and when receptors are found in the cell (also known as receptor trafficking) is determined by a combination of the biochemistry of the receptor itself as well as the presence of accessory proteins that help signal the cell to remove or insert receptors at the synaptic membrane.

AMPA receptors (AMPARs), are a family of neuronally expressed ligand-gated ion channels that are localized to the plasma membrane and activated by extracellular glutamate, the principal excitatory neurotransmitter in the brain. The regulation of trafficking of AMPARs to and from the cell surface is critical for the changes in neuronal synaptic strength associated with learning and memory. Dysfunctional AMPAR signaling has been implicated in various neurological disorders including epilepsy, ischemic stroke, Parkinson’s disease and chronic pain, and is suspected of playing a role in other pathophysiological conditions as well.

Ly6g6d and lypd2 are two ly6 proteins that reduce the ability of GluR2 receptors (a particular type of AMPAR) to respond to glutamate. We are interested in identifying the molecular mechanism underlying this change in GluR2 function. Using cell culture methods, we use immunofluorescence to identify where these proteins are found in the cell and western blotting techniques (co-immunoprecipitation) to identify whether or not these proteins can interact with each other.

Identifying ly6 gene expression and function in C. elegans

Our knowledge of ly6 function is based on a handful of notable examples studied across multiple species-- lynx1 and lynx2 in mice, sleepless in Drosophila, odr-2 in C. elegans, and bouncer in zebrafish, just to name a few. This leaves the functions of the remaining ly6 proteins largely unknown! Ideally we would like to address this by studying ly6 function from the perspective of the entire family of proteins-- are ly6s expressed in distinct or overlapping cell populations? do ly6s share the same targets or are they each specific to their target? 

To answer these questions, we'd like to introduce the newest model system in our lab: C. elegans! The C. elegans genome contains 10 genes with homology to the ly6 proteins. The founding member of this family is known as odr-2; the remaining members of the family are known as the hot genes ("homologs of odr-2"). In collaboration with Dr. Jennifer Wolff, we use worm genetics, fluorescence imaging, and behavioral assays to determine the gene expression patterns and functional roles of each hot gene.

Recombinant expression and purification of ly6 proteins 

Biochemistry allows us to study protein structure and function in beautiful molecular detail-- however, the first starting point for many biochemical experiments is obtaining stable, functional, purified protein. The goal for this project is to use tools from molecular biology and biochemistry to develop a protein expression system that allows us to reliably purify ly6 proteins using E. coli. To begin, we will focus on purifying odr-2 and the hot genes from C. elegans, with the goal of using this protein to do pulldown assays from worm lysate to identify potential interacting partners.