This project addresses the genetic factors responsible for the clinical expression of the most common form of porphyria in humans, namely porphyria cutanea tarda (PCT). Subnormal activity of hepatic uroporphyrinogen decarboxylase (URO-D) is a consistent finding in all patients with PCT. In some families the enzyme deficiency is inherited as an autosomal trait. This form of the disease is known as familial PCT. In other cases inherited factors are not obvious and the disease is called sporadic PCT. We have cloned and sequenced URO-D cDNA. We have identified a URO- D point substitution mutation in familial PCT which appears to affect protein stability. We plan to evaluate multiple pedigrees with familial PCT in order to catalogue the spectrum of URO-D mutations. Experimental methods will include cloning and sequencing of mutant cDNA's, oligonucleotide hybridization, and synthesis of mutant URO-D's in a bacterial expression system. The effects on the function and stability of URO-D resulting from the mutations will be studied. We have constructed cosmid libraries in order to search for polymorphisms in the flanking regions of the URO-D gene. We expect to define key structural elements in URO-D responsible for substrate binding, catalysis and protein stability. This will be accomplished using a variety of biochemical methods and site directed mutagenesis. Our approach to sporadic PCT will explore the hypothesis that patients with this disease have a mutation at the URO-D locus that renders the gene product sensitive to inhibitors generated in the liver. URO-D protein polymorphisms will be brought using electrophoresis over a wide pH range and URO-D cDNA's will be sequencer. Mutant proteins will be produced in a bacterial expression system and function effects of the mutations will be determined. This project focusses on one form of porphyria but information about structural features affecting protein stability and enzyme activity is applicable to many areas of human biology.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
Project #
Application #
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Utah
Schools of Medicine
Salt Lake City
United States
Zip Code
Yien, Yvette Y; Shi, Jiahai; Chen, Caiyong et al. (2018) FAM210B is an erythropoietin target and regulates erythroid heme synthesis by controlling mitochondrial iron import and ferrochelatase activity. J Biol Chem 293:19797-19811
Yien, Yvette Y; Ducamp, Sarah; van der Vorm, Lisa N et al. (2017) Mutation in human CLPX elevates levels of ?-aminolevulinate synthase and protoporphyrin IX to promote erythropoietic protoporphyria. Proc Natl Acad Sci U S A 114:E8045-E8052
Piel 3rd, Robert B; Shiferaw, Mesafint T; Vashisht, Ajay A et al. (2016) A Novel Role for Progesterone Receptor Membrane Component 1 (PGRMC1): A Partner and Regulator of Ferrochelatase. Biochemistry 55:5204-17
Kim, Hyung J; Jeong, Mi-Young; Parnell, Timothy J et al. (2016) The Plasma Membrane Protein Nce102 Implicated in Eisosome Formation Rescues a Heme Defect in Mitochondria. J Biol Chem 291:17417-26
Hanson, W Miachel; Chen, Zhe; Jackson, Laurie K et al. (2016) Reversible Oligonucleotide Chain Blocking Enables Bead Capture and Amplification of T-Cell Receptor ? and ? Chain mRNAs. J Am Chem Soc 138:11073-6
Bergonia, Hector A; Franklin, Michael R; Kushner, James P et al. (2015) A method for determining ?-aminolevulinic acid synthase activity in homogenized cells and tissues. Clin Biochem 48:788-95
Dailey, Harry A; Gerdes, Svetlana; Dailey, Tamara A et al. (2015) Noncanonical coproporphyrin-dependent bacterial heme biosynthesis pathway that does not use protoporphyrin. Proc Natl Acad Sci U S A 112:2210-5
Farrell, Colin P; Parker, Charles J; Phillips, John D (2015) Exome sequencing for molecular characterization of non-HFE hereditary hemochromatosis. Blood Cells Mol Dis 55:101-3
Langendonk, Janneke G; Balwani, Manisha; Anderson, Karl E et al. (2015) Afamelanotide for Erythropoietic Protoporphyria. N Engl J Med 373:48-59
Medlock, Amy E; Shiferaw, Mesafint T; Marcero, Jason R et al. (2015) Identification of the Mitochondrial Heme Metabolism Complex. PLoS One 10:e0135896

Showing the most recent 10 out of 59 publications