Effects of Glycosylation on Cholesterol Metabolism in Caenorhabditis elegans

Abstract

Transport of cholesterol within multi-cellular organisms is a vital life process. Research with cholesterol transport and metabolism using the Caenorhabditis elegans (C. elegans) is beneficial to the health science community because many biological processes are conserved between C. elegans and humans. Efficient cholesterol transport requires glycosylation, which is the modification of proteins with sugars. In nematodes, some of the glycosylated proteins (glycoproteins), called vitellogenins, play a role in cholesterol uptake in oocytes of C. elegans. There are a large number of glycosylation and cholesterol transport C elegans mutants available. Furthermore C. elegans present an unusual research advantage since they cannot synthesize cholesterol and must take it in from their outside environment. Since C. elegans must take in cholesterol from their outside environment, I hypothesized that abnormal glycosylation of vitellogenins impairs the transport of cholesterol in C. elegans. I tested this hypothesis with three approaches: quantifying cholesterol incorporation into C. elegans oocytes, assaying viability of glycosylation defective mutants grown under low or no sterol conditions, and comparing the total cholesterol content of glycosylation-defective mutants vs. wildtype animals. Through these studies, it was found that 1) srf-8 C. elegans have a significantly different accumulation of cholesterol than wildtype worms as determined by fluorescent cholesterol microscopy and, 2) srf-8 C. elegans have a slow hatching phenotype when grown in no or low-cholesterol conditions.