A Novel Role for Progesterone Receptor Membrane Component 1 (PGRMC1): A Partner and Regulator of Ferrochelatase.
Heme is an iron-containing cofactor essential for multiple cellular processes and fundamental activities such as oxygen transport. To better understand the means by which heme synthesis is regulated during erythropoiesis, affinity purification coupled with mass spectrometry (MS) was performed to identify putative protein partners interacting with ferrochelatase (FECH), the terminal enzyme in the heme biosynthetic pathway. Both progesterone receptor membrane component 1 (PGRMC1) and progesterone receptor membrane component 2 (PGRMC2) were identified in these experiments. These interactions were validated by reciprocal affinity purification followed by MS analysis and immunoblotting. The interaction between PGRMC1 and FECH was confirmed in vitro and in HEK 293T cells, a non-erythroid cell line. When cells that are recognized models for erythroid differentiation were treated with a small molecule inhibitor of PGRMC1, AG-205, there was an observed decrease in the level of hemoglobinization relative to that of untreated cells. In vitro heme transfer experiments showed that purified PGRMC1 was able to donate heme to apo-cytochrome b5. In the presence of PGRMC1, in vitro measured FECH activity decreased in a dose-dependent manner. Interactions between FECH and PGRMC1 were strongest for the conformation of FECH associated with product release, suggesting that PGRMC1 may regulate FECH activity by controlling heme release. Overall, the data illustrate a role for PGRMC1 in regulating heme synthesis via interactions with FECH and suggest that PGRMC1 may be a heme chaperone or sensor.
Department of Biochemistry and Molecular Biology, Biomedical and Health Sciences Institute, AU/UGA Medical Partnership, University of Georgia , Athens, Georgia 30602, United States.
Robert B
RB
Piel
Department of Biochemistry and Molecular Biology, Biomedical and Health Sciences Institute, AU/UGA Medical Partnership, University of Georgia , Athens, Georgia 30602, United States.
Mesafint T
MT
Shiferaw
Department of Biological Chemistry, University of California , Los Angeles, California 90095-1737, United States.
Ajay A
AA
Vashisht
Department of Biochemistry and Molecular Biology, Biomedical and Health Sciences Institute, AU/UGA Medical Partnership, University of Georgia , Athens, Georgia 30602, United States.
Jason R
JR
Marcero
Department of Biochemistry and Molecular Biology, Biomedical and Health Sciences Institute, AU/UGA Medical Partnership, University of Georgia , Athens, Georgia 30602, United States.
Jeremy L
JL
Praissman
Hematology Division, University of Utah School of Medicine , Salt Lake City, Utah 84132, United States.
John D
JD
Phillips
Department of Biological Chemistry, University of California , Los Angeles, California 90095-1737, United States.
James A
JA
Wohlschlegel
Department of Biochemistry and Molecular Biology, Biomedical and Health Sciences Institute, AU/UGA Medical Partnership, University of Georgia , Athens, Georgia 30602, United States.
Amy E
AE
Medlock
D000818:Animals; D002460:Cell Line; D005294:Ferrochelatase / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D011980:Receptors, Progesterone / Q000502:physiology*
D008565:Membrane Proteins; C115296:PGRMC1 protein, human; D011980:Receptors, Progesterone; D005294:Ferrochelatase