Hemin interactions and alterations of the subcellular localization of prion protein.
Hemin (iron protoporphyrin IX) is a crucial component of many physiological processes acting either as a prosthetic group or as an intracellular messenger. Some unnatural, synthetic porphyrins have potent anti-scrapie activity and can interact with normal prion protein (PrPC). These observations raised the possibility that hemin, as a natural porphyrin, is a physiological ligand for PrPC. Accordingly, we evaluated PrPC interactions with hemin. When hemin (3-10 microM) was added to the medium of cultured cells, clusters of PrPC formed on the cell surface, and the detergent solubility of PrPC decreased. The addition of hemin also induced PrPC internalization and turnover. The ability of hemin to bind directly to PrPC was demonstrated by hemin-agarose affinity chromatography and UV-visible spectroscopy. Multiple hemin molecules bound primarily to the N-terminal third of PrPC, with reduced binding to PrPC lacking residues 34-94. These hemin-PrPC interactions suggest that PrPC may participate in hemin homeostasis, sensing, and/or uptake and that hemin might affect PrPC functions.
Lee
Kil S
KS
Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, NIAID, National Institutes of Health, Hamilton, Montana 59840, USA.
Raymond
Lynne D
LD
Schoen
Brianna
B
Raymond
Gregory J
GJ
Kett
Lauren
L
Moore
Roger A
RA
Johnson
Lisa M
LM
Taubner
Lara
L
Speare
Jonathan O
JO
Onwubiko
Henry A
HA
Baron
Gerald S
GS
Caughey
Winslow S
WS
Caughey
Byron
B
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006427:Hemin / Q000378:metabolism* / Q000494:pharmacology; D006706:Homeostasis; D008024:Ligands; D051379:Mice; D018621:PrPC Proteins / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects
D008024:Ligands; D018621:PrPC Proteins; D006427:Hemin