The transport of heme to the liver by hemopexin has important consequences for the hepatocyte. Not only is biologically available iron conserved and toxic effects of peripheral heme prevented but also the transported heme regulates the expression of proteins involved in heme, heme-protein and iron metabolism. The ultimate goal of this research project is to elucidate the role and mechanism of action of the multimeric, membrane heme-binding protein (MHBP) of the hemopexin system in hepatic heme uptake, intracellular heme transport and gene regulation by heme. To achieve the goals of this research program, a basic approach is being taken in which the subunits of MHBP are being isolated and characterized, and their function in intracellular heme transport and regulation of protein expression delineated.
The specific aims for the 5 years of requested support are: 1. To continue to characterize biochemically important molecular properties of MHBP and its subunits, p17.5 (which bind heme) and p47; 2. To continue to delineate the role and mechanism of action of MHBP in intracellular heme transport by liver cells employing biochemical and morphological approaches; 3. To continue to define the regulation of hepatic proteins by receptor-mediated transport of heme and heme analogs; 4. To clone and sequence the cDNA for p17.5, the heme-binding subunit of MHBP, from liver cDNA libraries in hand, using available antibodies or oligonucleotide probes; and 5. To use the cloned cDNA to p17.5 of MHBP to investigate its expression. Several proteins have evolved to bind heme in order to direct the chemistry of the highly-reactive iron of this poorly water-soluble molecule. The basic information to be obtained from the research proposed here on MHBP will provide answers to fundamental questions concerning the homeostasis of hepatic heme and iron metabolism in health and disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK037463-04
Application #
3236392
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1989-06-01
Project End
1994-07-31
Budget Start
1989-09-01
Budget End
1990-07-31
Support Year
4
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Missouri Kansas City
Department
Type
Overall Medical
DUNS #
800772162
City
Kansas City
State
MO
Country
United States
Zip Code
64110
Paoli, Massimo; Marles-Wright, Jon; Smith, Ann (2002) Structure-function relationships in heme-proteins. DNA Cell Biol 21:271-80
Escriba, Pablo V; Morales, P; Smith, Ann (2002) Membrane phospholipid reorganization differentially regulates metallothionein and heme oxygenase by heme-hemopexin. DNA Cell Biol 21:355-64
Rocha, E R; Smith, A; Smith, C J et al. (2001) Growth inhibition of Bacteroides fragilis by hemopexin: proteolytic degradation of hemopexin to overcome heme limitation. FEMS Microbiol Lett 199:73-8
Shipulina, N V; Smith, A; Morgan, W T (2001) Effects of reduction and ligation of heme iron on the thermal stability of heme-hemopexin complexes. J Protein Chem 20:145-54
Sung, L; Shibata, M; Eskew, J D et al. (2000) Cell-surface events for metallothionein-1 and heme oxygenase-1 regulation by the hemopexin-heme transport system. Antioxid Redox Signal 2:753-65
Shipulina, N; Smith, A; Morgan, W T (2000) Heme binding by hemopexin: evidence for multiple modes of binding and functional implications. J Protein Chem 19:239-48
Smith, A (2000) Links between cell-surface events involving redox-active copper and gene regulation in the hemopexin heme transport system. Antioxid Redox Signal 2:157-75
Vanacore, R M; Eskew, J D; Morales, P J et al. (2000) Role for copper in transient oxidation and nuclear translocation of MTF-1, but not of NF-kappa B, by the heme-hemopexin transport system. Antioxid Redox Signal 2:739-52
Eskew, J D; Vanacore, R M; Sung, L et al. (1999) Cellular protection mechanisms against extracellular heme. heme-hemopexin, but not free heme, activates the N-terminal c-jun kinase. J Biol Chem 274:638-48
Smith, A; Eskew, J D; Borza, C M et al. (1997) Role of heme-hemopexin in human T-lymphocyte proliferation. Exp Cell Res 232:246-54

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