Moonlighting Protein Glyceraldehyde-3-Phosphate Dehydrogenase: A Cellular Rapid-Response Molecule for Maintenance of Iron Homeostasis in Hypoxia.
Antigens, CD
/ genetics
Cell Hypoxia
Cell Membrane
/ metabolism
Cytosol
/ metabolism
Glyceraldehyde-3-Phosphate Dehydrogenases
/ antagonists & inhibitors
Humans
Iron
/ metabolism
K562 Cells
Macrophages
/ cytology
Protein Binding
RNA Interference
RNA, Small Interfering
/ metabolism
Receptors, Transferrin
/ genetics
Transferrin
/ metabolism
GAPDH
Hypoxia
Iron
Rapid response
Journal
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology
ISSN: 1421-9778
Titre abrégé: Cell Physiol Biochem
Pays: Germany
ID NLM: 9113221
Informations de publication
Date de publication:
2019
2019
Historique:
received:
24
05
2018
accepted:
18
03
2019
entrez:
22
3
2019
pubmed:
22
3
2019
medline:
4
4
2019
Statut:
ppublish
Résumé
Hypoxia triggers a rapid increase in iron demand to meet the requirements of enhanced erythropoiesis. The mobilization of iron stores from macrophage to plasma as holo-transferrin (Tf) from where it is accessible to erythroid precursor cells impacts iron homeostasis. Despite the immediate need for enhanced iron uptake by bone marrow cells, numerous studies have shown that transferrin receptor levels do not rise until more than 24 hours after the onset of hypoxia, suggesting the existence of heretofore unknown rapid response cellular machinery for iron acquisition in the early stages of cellular hypoxia. We performed flow cytometry to measure cell surface levels of TfR1, GAPDH, and Tf binding after hypoxia treatment. We utilized FRET analysis and co-immunoprecipitation methods to establish the interaction between Tf and GAPDH. In the current study, we demonstrated that hypoxia induces K562 cells to translocate the cytosolic moonlighting protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) onto cell surfaces and into the extracellular milieu to acquire transferrin-bound iron, even while levels of the classical transferrin receptor TfR1 (CD71) remain suppressed. GAPDH knockdown confirmed this protein's role in transferrin acquisition. Interestingly, macrophages did not show enhanced levels of extracellular GAPDH under hypoxia. Our results suggest the role of GAPDH-mediated Tf uptake as a rapid response mechanism by which cells acquire iron during the early stages of hypoxia. This is a tissue-specific phenomenon for the distinct requirements of cells that are consumers of iron versus cells that play a role in iron storage and recycling. This rapid deployment of an abundantly available multipurpose molecule allows hypoxic cells to internalize more Tf and maintain enhanced iron supplies in the early stages of hypoxia before specialized receptors can be synthesized and deployed to the cell membrane.
Sections du résumé
BACKGROUND/AIMS
OBJECTIVE
Hypoxia triggers a rapid increase in iron demand to meet the requirements of enhanced erythropoiesis. The mobilization of iron stores from macrophage to plasma as holo-transferrin (Tf) from where it is accessible to erythroid precursor cells impacts iron homeostasis. Despite the immediate need for enhanced iron uptake by bone marrow cells, numerous studies have shown that transferrin receptor levels do not rise until more than 24 hours after the onset of hypoxia, suggesting the existence of heretofore unknown rapid response cellular machinery for iron acquisition in the early stages of cellular hypoxia.
METHODS
METHODS
We performed flow cytometry to measure cell surface levels of TfR1, GAPDH, and Tf binding after hypoxia treatment. We utilized FRET analysis and co-immunoprecipitation methods to establish the interaction between Tf and GAPDH.
RESULTS
RESULTS
In the current study, we demonstrated that hypoxia induces K562 cells to translocate the cytosolic moonlighting protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) onto cell surfaces and into the extracellular milieu to acquire transferrin-bound iron, even while levels of the classical transferrin receptor TfR1 (CD71) remain suppressed. GAPDH knockdown confirmed this protein's role in transferrin acquisition. Interestingly, macrophages did not show enhanced levels of extracellular GAPDH under hypoxia.
CONCLUSION
CONCLUSIONS
Our results suggest the role of GAPDH-mediated Tf uptake as a rapid response mechanism by which cells acquire iron during the early stages of hypoxia. This is a tissue-specific phenomenon for the distinct requirements of cells that are consumers of iron versus cells that play a role in iron storage and recycling. This rapid deployment of an abundantly available multipurpose molecule allows hypoxic cells to internalize more Tf and maintain enhanced iron supplies in the early stages of hypoxia before specialized receptors can be synthesized and deployed to the cell membrane.
Substances chimiques
Antigens, CD
0
CD71 antigen
0
RNA, Small Interfering
0
Receptors, Transferrin
0
Transferrin
0
Iron
E1UOL152H7
Glyceraldehyde-3-Phosphate Dehydrogenases
EC 1.2.1.-
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
517-531Subventions
Organisme : Department of Biotechnology, Ministry of Science and Technology
Pays : India
Organisme : Council of Scientific and Industrial Research
Pays : India
Organisme : University Grants Commission
Pays : India
Informations de copyright
© Copyright by the Author(s). Published by Cell Physiol Biochem Press.
Déclaration de conflit d'intérêts
The authors have no conflicts of interest to report.