Monitoring the Cellular Cholesterol Distribution via nanoSIMS Imaging

Cholesterol is a very important lipid, manufactured by all animal cells for their use. About 20-25% of total daily cholesterol production occurs in the liver; other sites that have higher synthesis rate are intestine, adrenal glands and reproductive organs. It is not only produced in the body cells but also it can be obtained from dietary sources as well. Presence of cholesterol is very crucial for animal cells, since it is the building block of cellular membranes provide membrane fluidity over the range of physiological temperatures; within the cell membrane, it also functions to regulate intracellular transport, cell signaling and nerve conduction. Moreover, it is a precursor for synthesis vitamin D and and steroid hormones. Cholesterol is such an important biological molecule for animal cells, yet it has been a real challenge so far, to understand distribution of cholesterol within the biological membranes. In our study, via using 13C labeled cholesterol, we are able to monitor incorporated cholesterol in cellular structures, with the help of combination of Electron Microscopy imaging and nanoSIMS imaging. Our aim in this study is to address a really fundamental question, what is the distribution gradient of cholesterol, through different layers of cellular membranes.