Cellular membranes are not simple barriers, and the appropriate membrane composition is essential toensure proper function of the membrane. In fact, dysfunction as a result of altered membrane compositionhas been observed in a wide range of diseases including cancers, neurodegenerative and age-relateddiseases. The composition of the membrane is known to impact its key properties including permeability,curvature, and fluidity; however, the lipid processing pathways and regulators that affect these compositionchanges have not yet been identified. This is largely due to the fact that in vivo studies of membranedynamics have been limited, because they require high levels of isotope enrichment to obtain the resolutionrequired to analyze membrane lipids in detail. In the Van Gilst lab, I developed stable isotope enrichmentstrategies in C. elegans that allow for the quantification of dietary carbon into the fatty acids of the animal.These isotope feeding strategies provide the enrichment levels required for flux analysis of phospholipidmembrane dynamics. In this proposal, I will expand the scope of these stable isotope tracer methods toassay the turnover and synthesis of the acyl chains and phospholipid head groups in membranes via gaschromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectometry (LC/MS),respectively. In doing so, I hope to define many of the pathways that impact membrane composition and itsability to respond to stress and ultimately contribute to the overall understanding of membrane biology anddynamics.One of the most dramatic impacts of membrane composition is in aging, where the phospholipids begin tocontain drastically more saturated fatty acids, ultimately making the membranes much more rigid andnegatively impacting their function. As examples, the increased saturation index in the aged membrane canaffect diffusion properties, transporter function, vesicle fusion, and even signaling. The progressiveaccumulation of saturated fat in the membranes over aging has been theorized as a major contributor toaging and aging-related dysfunction. The genetic tools of C. elegans will allow us to determine the relativecontribution of membrane turnover on the overall membrane composition in young and old animals. The goalof this proposal is to define the genetic regulators and pathways that influence membrane aging and, in doingso, contribute to the understanding of how membrane biology impacts the aging process.
The phospholipid composition of the membrane has a dramatic impact on the membrane's ability to function properly; and altered membrane composition has been associated with a wide array of diseases including cancers; neurodegenerative and age-related diseases. However; the mechanisms that are responsible for the aberrant changes in membrane composition have not yet been identified. Here; I will perform an in vivo study of membrane dynamics and maintenance in C. elegans to define the pathways that regulate membrane composition and how those pathways are altered during aging.
