The role of the erythroid-specific delta-aminolevulinate synthase gene expression in erythroid heme synthesis.
Using antisense technology, the effects of suppressed gene expression of the erythroid-specific delta-aminolevulinate (ALA) synthase (ALAS-E) on heme synthesis, expression of mRNAs encoding an erythroid-specific transcription factor NF-E2, other heme pathway enzymes, and beta-globin were examined in murine erythroleukemia (MEL) cells. In MEL cells in which an antisense ALAS-E RNA was expressed (AS clone), sense ALAS-E mRNA levels in both untreated and dimethylsulfoxide (DMSO)-treated cells were decreased compared with their respective controls. Heme synthesis in AS clones was decreased in proportion to the suppressed levels of ALAS-E mRNA. In addition, mRNAs for ALA dehydratase, porphobilinogen deaminase, ferrochelatase (FeC), and beta-globin were also decreased in AS clones. There was a strong correlation between the level of ALAS-E mRNA and most of the mRNAs of the heme pathway enzymes and beta-globin. There was a decrease in the mRNA level of p45, but not of mafK, which are the large and the small subunits of NF-E2, respectively, in AS clones. Treatment of AS cells with hemin and ALA in the presence of DMSO partially restored the suppressed mRNA levels for beta-globin and FeC and heme content, respectively. These findings thus indicate that heme formation, which is determined by the level of ALAS-E, plays an essential role on gene expression of many proteins necessary for erythroid development.
Meguro
K
K
Rockefeller University, New York, NY 10021, USA.
Igarashi
K
K
Yamamoto
M
M
Fujita
H
H
Sassa
S
S
D000624:5-Aminolevulinate Synthetase / Q000235:genetics*; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics; D015672:Erythroid Precursor Cells / Q000201:enzymology*; D050981:Erythroid-Specific DNA-Binding Factors; D005786:Gene Expression Regulation; D006418:Heme / Q000096:biosynthesis*; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism; D066298:In Vitro Techniques; D050985:MafK Transcription Factor; D051379:Mice; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D000623:Porphobilinogen Synthase / Q000378:metabolism; D016372:RNA, Antisense; D012333:RNA, Messenger / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050985:MafK Transcription Factor; C494696:Mafk protein, mouse; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; C494693:Nfe2 protein, mouse; D016372:RNA, Antisense; D012333:RNA, Messenger; D014157:Transcription Factors; D006418:Heme; D000624:5-Aminolevulinate Synthetase; D011163:Hydroxymethylbilane Synthase; D000623:Porphobilinogen Synthase