This proposal has been designed to advance the Principle Investigator (PI)towards his goal of academic independence. To attain that objective he will learn advanced molecular biology and mouse genetic techniques as well as liver pathology/histology in his studies of vitamin C regulation in the liver. Ascorbic acid (vitamin C) is a required essential micronutrient and effective antioxidant in humans. Two isoforms of the sodium-dependent vitamin C transporters (SVCT1 and SVCT2) are expressed in many human and mouse tissues, including the liver. Nothing is known regarding the regulation or relative contribution of the SVCT systems toward the overall vitamin C uptake process in the liver. Understanding these mechanisms is clinically relevant since many liver related diseases benefit from optimizing vitamin C body homeostasis. Our studies will use both an in vitro and in vivo approach to perform a comprehensive examination of the human liver vitamin C uptake process and regulation. We will determine the characteristics/kinetics of vitamin C uptake, characterize the hSVCTI and hSVCT2promoters, establish the relative contribution of hSVCTI and hSVCT2 towardtotal uptake using an siRNA approach and perform studies regardingthe effects of adaptive regulation of the vitamin C uptake process, all in human liver cells. In addition we will determine the characteristics/kinetics of vitamin C uptake in the liver of an in vivo mouse model that like humans is unable to synthesize vitamin C, establish the relative contribution of mSVCTI and mSVCT2 toward total uptake using the cre/lox system to generate liver specific knockouts of each gene independently, and continue our studies into adaptive regulation of vitamin C uptake in this in vivo model. Our studies into the mechanisms involved in maintaining and regulating normal vitamin C body homeostasis will potentially allow clinicians to develop effective strategies for patients during conditions of deficiency. The extensive training and educational opportunities will allow the PI to launch into a career as an independent academic researcher.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Scientist Development Award - Research & Training (K01)
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Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Podskalny, Judith M,
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University of California Irvine
Internal Medicine/Medicine
Schools of Medicine
United States
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Reidling, Jack C; Rubin, Stanley A (2011) Promoter analysis of the human ascorbic acid transporters SVCT1 and 2: mechanisms of adaptive regulation in liver epithelial cells. J Nutr Biochem 22:344-50
Reidling, Jack C; Lambrecht, Nils; Kassir, Mohammad et al. (2010) Impaired intestinal vitamin B1 (thiamin) uptake in thiamin transporter-2-deficient mice. Gastroenterology 138:1802-9
Subramanian, Veedamali S; Marchant, Jonathan S; Reidling, Jack C et al. (2008) N-Glycosylation is required for Na+-dependent vitamin C transporter functionality. Biochem Biophys Res Commun 374:123-7
Subramanian, Veedamali S; Reidling, Jack C; Said, Hamid M (2008) Differentiation-dependent regulation of the intestinal folate uptake process: studies with Caco-2 cells and native mouse intestine. Am J Physiol Cell Physiol 295:C828-35
Reidling, Jack C; Subramanian, Veedamali S; Dahhan, Tamara et al. (2008) Mechanisms and regulation of vitamin C uptake: studies of the hSVCT systems in human liver epithelial cells. Am J Physiol Gastrointest Liver Physiol 295:G1217-27
Reidling, Jack C; Said, Hamid M (2007) Regulation of the human biotin transporter hSMVT promoter by KLF-4 and AP-2: confirmation of promoter activity in vivo. Am J Physiol Cell Physiol 292:C1305-12
Reidling, Jack C; Nabokina, Svetlana M; Said, Hamid M (2007) Molecular mechanisms involved in the adaptive regulation of human intestinal biotin uptake: A study of the hSMVT system. Am J Physiol Gastrointest Liver Physiol 292:G275-81