Glyoxalate reductase/hydroxypyruvate reductase interacts with the sodium-dependent vitamin C transporter-1 to regulate cellular vitamin C homeostasis.

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 Apr 18; Authors: Subramanian VS, Nabokina SM, Patton JR, Marchant JS, Moradi H, Said HM Abstract The human sodium-dependent vitamin C transporter 1 (hSVCT1) contributes to cellular uptake of ascorbic acid (AA). While 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 co-immunoprecipitation and mammalian two-hybrid firefly luciferase assays. This interaction had functional significance as co-expression of hGR/HPR with hSVCT1 led to an increase in AA uptake. Reciprocally, siRNA mediated knock down 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 co-expressing GFP-hSVC...
Source: American Journal of Physiology. Gastrointestinal and Liver Physiology - Category: Physiology Authors: Tags: Am J Physiol Gastrointest Liver Physiol Source Type: research