The main aim of this proposal is to allow the principle investigator to become more independent and to perform a pilot study in the area of cell biology with an emphasis on the membrane targeting and trafficking of vitamin C transporter and to generate additional publications and data for future grants. Vitamin C (ascorbic acid) is essential for normal human growth and development. Human intestine and other tissues express two sodium-dependent vitamin C transporters (hSVCT1 and -2). Recent studies have shown the involvement of specific Rab proteins in the membrane targeting/localization, trafficking and function of membrane proteins in intestinal cells. To date, nothing is known about the role of Rab proteins in cell biology and transport physiological aspects of hSVCT1 with specific regards to membrane targeting/localization, trafficking and function in human enterocytes. Recent studies have shown that the alteration in membrane targeting and trafficking events may affect the polarized expression of the given transporters and lead to overall impaired absorption/secretion in epithelia. Further, these cellular events were found to play an important role in the regulation of certain transport processes via insertion/retrieval of the involved transporters to and from the cell membrane. Therefore, studies aimed at regulators such as Rab proteins in membrane targeting and trafficking of transport proteins are of great significance and of cell biological/physiological importance. Recent studies have shown the involvement of Rab8a and 11a in the membrane targeting and trafficking of transport proteins in intestinal epithelial cells and also linked the proteins to human intestinal microvillus inclusion disease.
Our specific aim i s to determine the role of Rab8a and 11a proteins in polarized membrane targeting/localization, trafficking and function of hSVCT1 in vitro using human enterocytes and confirm results in vivo using Rab8a knockout mice. In these investigations we will use a combination of cell/biochemical/molecular biological and imaging methods. Outcome of these investigations will not only provide the applicant an opportunity to reach his career goals but also contribute to enhance the understanding of the cell biology of hSVCT1 and also other micronutrient transporters.
Vitamin C is an essential nutrient for human well-being and cannot be synthesized, obtains it from diet via intestinal absorption. Human intestine plays a role in regulating and maintaining body vitamin C homeostasis, studies on the cell biology/physiology of its transporters in intestinal cells are important. Outcome of these investigations will assist us to optimize intestinal vitamin C levels in deficiency and sub-optimal levels.
