CURF 1: About Me and ENaC Research

Hello! My name is Emma Perrault, and I am a junior studying Biochemistry, with a minor in Chemistry. I am an undergraduate researcher in Dr. Brodsky’s lab in the Department of Biological Sciences, and Dr. Brodsky is my research mentor. Something unique about me is that I tap danced for over ten years!

My project focuses on an ion channel called the epithelial sodium channel (ENaC). Ion channels are specialized proteins that transport charged molecules, most commonly sodium, potassium, chloride, and calcium, across the outer barrier of the cell (i.e., the cell membrane). Specifically, ENaC enables reabsorption of sodium in the kidneys. Sodium is transported from blood flowing through the tubular system of the kidneys into the bloodstream, a process necessary for the maintenance of water and salt levels in the body and the regulation of blood pressure. As a result, ENaC expression and activity must be tightly regulated to maintain blood pressure within normal limits, and mutations in the gene that encodes ENaC are associated with abnormal blood pressure.

ENaC is made up of three different proteins, α, β, and γ, that must fold and assemble properly. When the ENaC subunits are improperly folded or fail to assemble, the cell tries to get rid of the damaged protein. One of the ways that cells degrade proteins, particularly ion channels, is endoplasmic reticulum-associated degradation (ERAD). As its name implies, ERAD takes place in the endoplasmic reticulum, a subcellular structure that plays an important role in protein processing. Proteins known as molecular chaperones recognize ERAD substrates and target them for degradation by recruiting the necessary machinery, such as proteins called E3 ubiquitin ligases. In turn, E3 ubiquitin ligases mark proteins for degradation by adding ubiquitin, a small protein. Ubiquitinated proteins are then moved from the ER to the cytoplasm, where a protein complex called the proteasome degrades the protein.

BiP is a molecular chaperone in the ER that recognizes ERAD substrates when it is bound to ATP. Nucleotide exchange factors (NEFs) are proteins necessary to release the ERAD substrate from BiP so that the protein can attempt to fold properly or be degraded. In yeast, Lhs1 is one of the NEFs that acts on BiP. Previous work in the Brodsky lab demonstrated that Lhs1 and its mammalian homolog GRP170 facilitate the ERAD of the ENaC α subunit. However, it is not yet fully understood how Lhs1 targets ENaC for degradation.

The specific goal of my project is to determine how mutations in different domains of Lhs1 affect how Lhs1 facilitates ENaC degradation, which will help us to understand how Lhs1 targets ENaC for degradation. Proteins can contain one or more domains, which are distinct structural and functional units of the protein. To determine how the mutations affect Lhs1’s interaction with ENaC and the degradation of ENaC, I will create plasmid constructs that contain Lhs1 or a mutant version of Lhs1 to express in yeast cells. Then, I will utilize a variety of biochemical techniques, such as immunoprecipitation and cycloheximide chase analysis, and compare the mutated Lhs1 constructs to wild-type Lhs1. Using this information, I will be able to determine which interactions are essential to support maximal ENaC degradation and how Lhs1 functions in the ENaC degradation pathway. It is important to study how Lhs1 modulates ENaC degradation so we can understand how to treat diseases that are associated with improper degradation of ENaC. This will have a profound impact on the patients with these diseases and provide further insight into the complex cellular processes that cause them.

After graduation, I hope to attend medical school and become a physician. Partaking in the CURF will help me pursue my professional goals in a multitude of ways. I will be able to continue applying and expanding upon the principles that I learn in my courses, further develop my research skills, and gain invaluable experience that will be beneficial in my future career as a physician. The CURF will also allow me to continue to develop presentation and communication skills, as I share my research with other undergraduate students and faculty of various academic backgrounds. These are critical skills that will not only benefit me as an undergraduate student but also as I pursue a career in medicine. Research is an essential part of medical school and becoming a physician, and, with extensive research experience as an undergraduate, I will have the skills necessary to excel in my future research pursuits.

Some recent yeast media plates as I begin working on my project!

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