Genome-wide analysis reveals novel genes essential for heme homeostasis in Caenorhabditis elegans.

TitleGenome-wide analysis reveals novel genes essential for heme homeostasis in Caenorhabditis elegans.
Publication TypeJournal Articles
Year of Publication2010
AuthorsSeverance S, Rajagopal A, Rao AU, Cerqueira GC, Mitreva M, El-Sayed NM, Krause M, Hamza I
JournalPLoS Genet
Date Published2010 Jul
KeywordsAnimals, Caenorhabditis elegans, Dose-Response Relationship, Drug, Gene Expression Profiling, Gene Expression Regulation, genes, Genome-Wide Association Study, Heme, Homeostasis, HUMANS, Leishmania, Nematoda, Trypanosoma

Heme is a cofactor in proteins that function in almost all sub-cellular compartments and in many diverse biological processes. Heme is produced by a conserved biosynthetic pathway that is highly regulated to prevent the accumulation of heme--a cytotoxic, hydrophobic tetrapyrrole. Caenorhabditis elegans and related parasitic nematodes do not synthesize heme, but instead require environmental heme to grow and develop. Heme homeostasis in these auxotrophs is, therefore, regulated in accordance with available dietary heme. We have capitalized on this auxotrophy in C. elegans to study gene expression changes associated with precisely controlled dietary heme concentrations. RNA was isolated from cultures containing 4, 20, or 500 microM heme; derived cDNA probes were hybridized to Affymetrix C. elegans expression arrays. We identified 288 heme-responsive genes (hrgs) that were differentially expressed under these conditions. Of these genes, 42% had putative homologs in humans, while genomes of medically relevant heme auxotrophs revealed homologs for 12% in both Trypanosoma and Leishmania and 24% in parasitic nematodes. Depletion of each of the 288 hrgs by RNA-mediated interference (RNAi) in a transgenic heme-sensor worm strain identified six genes that regulated heme homeostasis. In addition, seven membrane-spanning transporters involved in heme uptake were identified by RNAi knockdown studies using a toxic heme analog. Comparison of genes that were positive in both of the RNAi screens resulted in the identification of three genes in common that were vital for organismal heme homeostasis in C. elegans. Collectively, our results provide a catalog of genes that are essential for metazoan heme homeostasis and demonstrate the power of C. elegans as a genetic animal model to dissect the regulatory circuits which mediate heme trafficking in both vertebrate hosts and their parasites, which depend on environmental heme for survival.

Alternate JournalPLoS Genet.
PubMed ID20686661
PubMed Central IDPMC2912396
Grant ListF32DK080603 / DK / NIDDK NIH HHS / United States
R01AI081803 / AI / NIAID NIH HHS / United States
R01DK74797 / DK / NIDDK NIH HHS / United States
/ / Intramural NIH HHS / United States