Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells
ABSTRACT: Insufficient absorption of iron and the consequent development of iron deficiency have serious health consequences. Hence, identification and development of iron delivery systems that can increase the bioavailability and uptake of dietary iron are important. Osteopontin (OPN) is an acidic...
Saved in:
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-01-01
|
| Series: | Journal of Dairy Science |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022030224012359 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850105339364507648 |
|---|---|
| author | Emilie H. Buhl Brian Christensen Freja H. Pedersen Esben S. S⊘rensen |
| author_facet | Emilie H. Buhl Brian Christensen Freja H. Pedersen Esben S. S⊘rensen |
| author_sort | Emilie H. Buhl |
| collection | DOAJ |
| description | ABSTRACT: Insufficient absorption of iron and the consequent development of iron deficiency have serious health consequences. Hence, identification and development of iron delivery systems that can increase the bioavailability and uptake of dietary iron are important. Osteopontin (OPN) is an acidic and highly phosphorylated integrin-binding protein found in milk where it exists as a full-length protein and as N-terminally derived fragments. Milk OPN can be taken up by enterocytes and transported across the intestinal barrier into the circulation. Milk OPN has previously been shown to bind calcium and magnesium. This study investigates milk OPN as a carrier of iron and its potential to increase iron absorption in intestinal cells. Full-length OPN and N-terminal fragments of OPN were shown to bind ∼30 and ∼10 mol of iron, respectively, and the phosphorylated residues were crucial for iron binding. Osteopontin retained iron bound after simulated gastrointestinal digestion. Immunodetection of digested OPN and OPN-Fe complexes showed that the OPN-Fe complexes were more resistant to pepsin digestion than OPN without bound iron. The cellular uptake of iron was investigated by measuring intracellular ferritin formation and mRNA expression of divalent metal transporter 1 in Caco-2 cells. Osteopontin increased the uptake of iron even in the presence of phytic acid, a dietary inhibitor of iron absorption. These data indicate that OPN can function as an iron carrier for use in alternative strategies for delivering iron in a bioavailable form for intestinal uptake. |
| format | Article |
| id | doaj-art-5ff44f71b5fe44d2b68dac62401e479f |
| institution | OA Journals |
| issn | 0022-0302 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Dairy Science |
| spelling | doaj-art-5ff44f71b5fe44d2b68dac62401e479f2025-08-20T02:39:08ZengElsevierJournal of Dairy Science0022-03022025-01-0110819010010.3168/jds.2024-25305Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cellsEmilie H. Buhl0Brian Christensen1Freja H. Pedersen2Esben S. S⊘rensen3Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, DenmarkDepartment of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, DenmarkDepartment of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, DenmarkCorresponding author; Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, DenmarkABSTRACT: Insufficient absorption of iron and the consequent development of iron deficiency have serious health consequences. Hence, identification and development of iron delivery systems that can increase the bioavailability and uptake of dietary iron are important. Osteopontin (OPN) is an acidic and highly phosphorylated integrin-binding protein found in milk where it exists as a full-length protein and as N-terminally derived fragments. Milk OPN can be taken up by enterocytes and transported across the intestinal barrier into the circulation. Milk OPN has previously been shown to bind calcium and magnesium. This study investigates milk OPN as a carrier of iron and its potential to increase iron absorption in intestinal cells. Full-length OPN and N-terminal fragments of OPN were shown to bind ∼30 and ∼10 mol of iron, respectively, and the phosphorylated residues were crucial for iron binding. Osteopontin retained iron bound after simulated gastrointestinal digestion. Immunodetection of digested OPN and OPN-Fe complexes showed that the OPN-Fe complexes were more resistant to pepsin digestion than OPN without bound iron. The cellular uptake of iron was investigated by measuring intracellular ferritin formation and mRNA expression of divalent metal transporter 1 in Caco-2 cells. Osteopontin increased the uptake of iron even in the presence of phytic acid, a dietary inhibitor of iron absorption. These data indicate that OPN can function as an iron carrier for use in alternative strategies for delivering iron in a bioavailable form for intestinal uptake.http://www.sciencedirect.com/science/article/pii/S0022030224012359osteopontiniron bindingiron absorptionbioavailability |
| spellingShingle | Emilie H. Buhl Brian Christensen Freja H. Pedersen Esben S. S⊘rensen Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells Journal of Dairy Science osteopontin iron binding iron absorption bioavailability |
| title | Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells |
| title_full | Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells |
| title_fullStr | Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells |
| title_full_unstemmed | Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells |
| title_short | Milk osteopontin has high iron-binding capacity and facilitates iron absorption in intestinal cells |
| title_sort | milk osteopontin has high iron binding capacity and facilitates iron absorption in intestinal cells |
| topic | osteopontin iron binding iron absorption bioavailability |
| url | http://www.sciencedirect.com/science/article/pii/S0022030224012359 |
| work_keys_str_mv | AT emiliehbuhl milkosteopontinhashighironbindingcapacityandfacilitatesironabsorptioninintestinalcells AT brianchristensen milkosteopontinhashighironbindingcapacityandfacilitatesironabsorptioninintestinalcells AT frejahpedersen milkosteopontinhashighironbindingcapacityandfacilitatesironabsorptioninintestinalcells AT esbenssrensen milkosteopontinhashighironbindingcapacityandfacilitatesironabsorptioninintestinalcells |