Recognition, Cointernalization, and Recycling of an Avian Riboflavin Carrier Protein in Human Placental Trophoblasts

Mason, Charles E.; D'Souza, Vanessa M.; Bareford, Lisa M.; Phelps, Mitch A.; Ray, Abhijit; Swaan, Peter W.

doi:10.1124/jpet.105.096149

Cited by 18 publications

(20 citation statements)

References 30 publications

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“…at ASPET Journals on May 10, 2018 molpharm.aspetjournals.org conditions further corroborates prior evidence suggesting that this vitamin is internalized via CME Swaan, 2000, 2001;Huang et al, 2003;Phelps et al, 2004;D'Souza et al, 2006a,b;Mason et al, 2006). Furthermore, the reduced absorption of B 2 (40%) directly correlated with ϳ80% reduced protein expression for DNM2 (Fig.…”

Section: Riboflavin-endocytosis Involves Dynamin 2 557supporting

confidence: 76%

“…Because both clathrin and Rab5 are endocytic markers of CME, these data suggest that B 2 absorption involves CME. Furthermore, analogous to the wellcharacterized CME ligand, transferrin, a B 2 carrier protein has been proposed to sequester free extracellular B 2 and facilitate its transport to endosomal organelles (Mason et al, 2006). Although such a soluble carrier protein has been characterized in oviparous species (Abrams et al, 1988;Zheng et al, 1988), the identity of a human homolog remains elusive.…”

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confidence: 99%

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Dynamin 2 Regulates Riboflavin Endocytosis in Human Placental Trophoblasts

Foraker¹,

Ray²,

Silva³

et al. 2007

Mol Pharmacol

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Riboflavin is thoroughly established to be indispensable in a multitude of cellular oxidation-reduction reactions through its conversion to coenzyme forms flavin mononucleotide and flavin adenine dinucleotide. Despite its physiological importance, little is known about specific mechanisms or proteins involved in regulating its cellular entry in humans. Studies involving biochemical modulators and immunological inhibition assays have indirectly revealed that riboflavin internalization and trafficking occurs at least in part through a clathrin-dependent receptormediated endocytic process. Here, using a two-tiered strategy involving RNA interference and the overexpression of dominant-negative constructs, we directly show the involvement of this endocytic mechanism through the requirement of the pluripotent endocytic vesicle scission enzyme, dynamin 2 GTPase, in human placental trophoblasts. Similar to the endocytic control ligand, transferrin, riboflavin is shown to exhibit 50% dependence on the functional expression of dynamin 2 for its active cellular entry. Furthermore, this reduced vitamin uptake correlates with Ͼ2-fold higher riboflavin association at the cell surface. In addition, fluorescent ligand endocytosis assays showing colocalization between rhodamine-riboflavin and the immunostained caveolar coat protein, caveolin 1, suggest that the active absorption of this important nutrient involves multiple and distinct endocytosis pathways.

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Section: Riboflavin-endocytosis Involves Dynamin 2 557supporting

confidence: 76%

mentioning

confidence: 99%

Dynamin 2 Regulates Riboflavin Endocytosis in Human Placental Trophoblasts

Foraker¹,

Ray²,

Silva³

et al. 2007

Mol Pharmacol

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“…In this context, the higher zeta potentials in FCS and in the 1:1 mixture of 5% glucose and FCS indicate some amount of loss in stability due to non-specific protein adsorption as described above. However, it is important to note that binding of soluble RCP to FLUSPIO, may even be beneficial for cellular targeting and uptake [25].…”

Section: Fluspio Characterizationmentioning

confidence: 99%

In vivo evaluation of riboflavin receptor targeted fluorescent USPIO in mice with prostate cancer xenografts

et al. 2016

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Riboflavin (Rf) receptors bind and translocate Rf and its phosphorylated forms (e.g. flavin mononucleotide, FMN) into cells where they mediate various cellular metabolic pathways. Previously, we showed that FMN-coated ultrasmall superparamagnetic iron oxide (FLUSPIO) nanoparticles are suitable for labeling metabolically active cancer and endothelial cells in vitro. In this study, we focused on the in vivo application of FLUSPIO using prostate cancer xenografts. Size, charge, and chemical composition of FLUSPIO were evaluated. We explored the in vitro specificity of FLUSPIO for its cellular receptors using magnetic resonance imaging (MRI) and Prussian blue staining. Competitive binding experiments were performed in vivo by injecting free FMN in excess. Bio-distribution of FLUSPIO was determined by estimating iron content in organs and tumors using a colorimetric assay. AFM analysis and zeta potential measurements revealed a particulate morphology approximately 20-40 nm in size and a negative zeta potential (-24.23 ± 0.15 mV) in water. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry data confirmed FMN present on the USPIO nanoparticle surface. FLUSPIO uptake in prostate cancer cells and human umbilical vein endothelial cells was significantly higher than that of control USPIO, while addition of excess of free FMN reduced accumulation. Similarly, in vivo MRI and histology showed specific FLUSPIO uptake by prostate cancer cells, tumor endothelial cells, and tumor-associated macrophages. Besides prominent tumor accumulation, FLUSPIO accumulated in the liver, spleen, lung, and skin. Hence, our data strengthen our hypothesis that targeting riboflavin receptors is an efficient approach to accumulate nanomedicines in tumors opening perspectives for the development of diagnostic and therapeutic systems.

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“…To demonstrate this, we utilized the BA-PhO-Dex-SWNT construct as an intracellular riboflavin sensor. Riboflavin is an essential vitamin for eukaryotic organisms and its transport is typically facilitated by riboflavin carrier protein 44 , for which elevated levels may predict late-stage (stage III or IV) breast cancer with 100% accuracy 45 . We incubated BA-PhO-Dex-SWNT with Raw 264.7 macrophage cells in a riboflavin-free medium 13 overnight (Fig.…”

Section: Tracking Riboflavin Diffusion In Macrophage Cellsmentioning

confidence: 99%