Glyoxalate reductase/hydroxypyruvate reductase interacts with the sodium-dependent vitamin C transporter-1 to regulate cellular vitamin C homeostasis. Am J Physiol Gastrointest Liver Physiol 2013 Jun 15;304(12):G1079-86
Date
04/20/2013Pubmed ID
23599041Pubmed Central ID
PMC3680717DOI
10.1152/ajpgi.00090.2013Scopus ID
2-s2.0-84879147148 (requires institutional sign-in at Scopus site) 10 CitationsAbstract
The human sodium-dependent vitamin C transporter 1 (hSVCT1) contributes to cellular uptake of ascorbic acid (AA). Although different aspects of hSVCT1 cell biology have been extensively studied, nothing is currently known about the broader hSVCT1 interactome that modulates its role in cellular physiology. Here, we identify the enzyme human glyoxalate reductase/hydroxypyruvate reductase (hGR/HPR) as an hSVCT1 associated protein by yeast two-hybrid (Y2H) screening of a human liver cDNA library. The interaction between hSVCT1 and hGR/HPR was further confirmed by in vitro GST pull-down assay, in vivo coimmunoprecipitation and mammalian two-hybrid firefly luciferase assays. This interaction had functional significance as coexpression of hGR/HPR with hSVCT1 led to an increase in AA uptake. Reciprocally, siRNA-mediated knockdown of endogenous hGR/HPR led to an inhibition of AA uptake. Given that oxalate is a degradation product of vitamin C and hGR/HPR acts to limit cellular oxalate levels, this association physically couples two independent regulators of cellular oxalate production. Furthermore, confocal imaging of human liver HepG2 cells coexpressing GFP-hSVCT1 and hGR/HPR-mCherry demonstrated that these two proteins colocalize within a subpopulation of intracellular organelles. This provides a possible molecular basis for organellar AA transport and regulation of local glyoxylate/glycolate concentration in the vicinity of organelle membranes.
Author List
Subramanian VS, Nabokina SM, Patton JR, Marchant JS, Moradi H, Said HMAuthor
Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Alcohol OxidoreductasesAscorbic Acid
Hep G2 Cells
Homeostasis
Humans
Intracellular Membranes
Liver
Oxalates
Protein Binding
Protein Transport
RNA, Small Interfering
Sodium-Coupled Vitamin C Transporters
Two-Hybrid System Techniques