Undergraduate Honors Thesis Projects

Date of Award

4-8-2020

Document Type

Honors Paper

Degree Name

Biochemistry and Molecular Biology-BS

Department

Chemistry

Advisor

John Tansey

First Committee Member

Dr. John Tansey

Second Committee Member

Dr. David Sheridan

Third Committee Member

Dr. Cynthia Laurie-Rose

Keywords

Lipid Metabolism, Disease, Health Issues, Protein Trafficking

Subject Categories

Biochemistry | Higher Education | Molecular Biology

Abstract

Many modern health issues arise from aberrant lipid metabolism, among these are type II diabetes and non-alcoholic fatty liver disease. One commonality these diseases share is neutral lipid metabolism and storage. Regulation of neutral lipid metabolism is of vital importance in the body, and among the proteins responsible for such regulation are the perilipins. Perilipins are a family of five conserved proteins that are found on the surface of lipid storage droplets and play a central role in the regulation of cellular neutral lipid metabolism. Perilipin 5 specifically, is expressed in tissues with a high capacity for fatty acid oxidation such as cardiac muscle, oxidative muscle, and fasting liver. Using western blotting and reverse transcriptase PCR, we have identified a splice variant of perilipin 5 we have termed perilipin 5b. This shortened form of the protein retains the amino terminal 35 kDa of the protein but lacks the putative 4-helix bundle found in the C-terminus. Based on the reports in the literature, this protein would lack the carboxy terminal domains reported to be necessary for interactions with lipases and other proteins but would retain serine 155 that is requisite for PKA phosphorylation and translocation to the nucleus. We have constructed a carboxy terminal truncation of perilipin 5 and are expressing it in CHO cells to further define the function of this protein. Immunofluoresence microscopy of CHO cells expressing perilipin 5b shows localization on lipid storage droplets and on puncta in the cytosol. Stimulation of the PKA signaling pathway in these cells leads to the phosphorylation of perilipin 5 and a shift to the nucleus. Collectively these data indicate that perilipin 5b plays a role in lipid storage, but the function of this truncation is still unknown.

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