Heme biosynthesis is an essential process in erythroid and non-erythroid cells. Porphyria cutanea tarda (PCT), a defect in step 5 of the heme biosynthetic pathway, represents the most common form of porphyria in humans. PCT is due reduced specific activity uroporphyrinogen decarboxylase (URO- D), and results in a massive accumulation of the intermediate, uroporphyrin. We have shown that an ABC-type transporter is responsible for moving uroporphyrin into the vacuole in yeast. We will identify the mammalian transporter through targeted proteomics and complementation in yeast. We will confirm the transporter identity by knocking down the candidate in cells and looking for porphyrin localization. We will also define the method used by cells to transfer porphyrins from the lysosome to the cytosol. Our second specific aim will utilize a yeast model of erythropoietic protoporphyria (EPP) to identify the transport protein required to move protoporphyrin from the mitochondrial matrix to the cytosol. Collectively, these studies will define the transport mechanisms involved in the movement of porphyrin intermediates within and from cells. The identified transporters are potential associated risk factors that may explain the phenotypic diversity observed in the PCT and EPP phenotypes.

Public Health Relevance

This project will identify proteins that transport intermediates of the heme synthesis pathway across cellular membranes. Identifying these proteins will aid in the treatment of the porphyric disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
High Priority, Short Term Project Award (R56)
Project #
2R56DK020503-33
Application #
8703363
Study Section
Molecular and Cellular Hematology (MCH)
Program Officer
Bishop, Terry Rogers
Project Start
1977-09-01
Project End
2014-08-31
Budget Start
2013-09-09
Budget End
2014-08-31
Support Year
33
Fiscal Year
2013
Total Cost
$149,000
Indirect Cost
$49,000
Name
University of Utah
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112