Biomaterial Database

Receptor-mediated transport of heme by hemopexin regulates gene expression in mammalian cells. 1989

J Alam, and A Smith

Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans 70112.

Hemopexin (HPX) transports heme to liver parenchymal cells, undergoes receptor-mediated endocytosis, and recycles intact. Incubation of mouse hepatoma (Hepa) cells with heme-HPX causes a rapid dose- and time-dependent increase in the steady-state level of heme oxygenase (HO) mRNA. A maximum induction of 20-25-fold is achieved within 3 h after incubation with 10 microM heme-HPX. This accumulation of HO mRNA results primarily from increased transcription of the HO gene as judged by in vitro nuclear run-on assays. In addition, receptor-mediated transport of heme into Hepa cells significantly decreases the steady-state level of transferrin receptor (TfR) mRNA. While a 25-30-fold decrease in the amount of TfR mRNA is observed within 3 h of incubation of Hepa cells with 10 microM heme-HPX, no significant change in the rate of TfR gene transcription was detected. These regulatory effects of heme-HPX are not restricted to hepatic cells but are also observed in human promyelocytic HL-60 cells. This is the first direct demonstration of receptor-mediated transport of heme by hemopexin regulating gene expression in mammalian cells.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008114	Liver Neoplasms, Experimental	Experimentally induced tumors of the LIVER.	Hepatoma, Experimental,Hepatoma, Morris,Hepatoma, Novikoff,Experimental Hepatoma,Experimental Hepatomas,Experimental Liver Neoplasms,Hepatomas, Experimental,Neoplasms, Experimental Liver,Experimental Liver Neoplasm,Liver Neoplasm, Experimental,Morris Hepatoma,Novikoff Hepatoma
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004705	Endocytosis	Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.	Endocytoses
D005796	Genes	A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.	Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D006418	Heme	The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.	Ferroprotoporphyrin,Protoheme,Haem,Heme b,Protoheme IX
D006466	Hemopexin
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia