Imaging of lipid membrane organization and internalization pathways of cell penetrating peptides
Abstract
Lipid bilayer, as the critical structural component of plasma membrane, is of significant important to cellular functions. Understanding the organization of lipids can give a better understanding of the activities of the cells. Chapter one to chapter three of this work described the efforts and approaches of using model lipid systems and imaging techniques to understand the fundamental properties of lateral distribution of lipids in bilayers. Using Coherent anti-Stokes Raman microscopy (CARS), a vibrational imaging method, the partition of d62-DPPC between the two co-existing domains in single DOPC/d62-DPPC supported bilayers at different levels of cholesterol was first quantitatively measured. The study provides us a firm understanding of the chemical nature of lipid membrane systems. The work also described the first systematic imaging study of phase segregation in GUVs (giant unilamellar vesicle) composed of DPPC/DOPC or DPPC/DLPC. The significant finding in this study is that the phase behavior of binary GUVs is correlated to their thermoelastic properties. CPPs have received extensive attention owing to their ability to bring cargoes inside of cells. Chapter five and chapter six of this work were focused on the study of cellular uptake mechanism of cell penetrating peptides (CPPs). Two different types of CPPs were studied in our work; one is the most intensively studied TAT peptide, which is a highly cationic CPP derived from the human immunodeficiency virus type 1 (HIV-1) and another one is P11LRR, a cationic amphiphilic polyproline helix developed by Dr. Chmielewski's group. An invagination-based mechanism of TAT-mediated uptake was proposed based on the results obtained with live cell imaging and model membrane studies. P11LRR was found to be able to target intracellular mitochondria. The mitochondria-targeting mechanism was characterized and attributed to direct membrane transport capability and amphiphilicity of P11LRR.
Degree
Ph.D.
Advisors
Cheng, Purdue University.
Subject Area
Analytical chemistry
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