Deficient heme and globin synthesis in embryonic stem cells lacking the erythroid-specific delta-aminolevulinate synthase gene.
The erythroid-specific isoform of delta-aminolevulinate synthase (ALAS-E) catalyzes the first step of heme biosynthesis in erythroid cells, and ALAS-E gene mutations are known to be responsible for x-linked sideroblastic anemia. To study the role of ALAS-E in erythroid development, we prepared mouse embryonic stem (ES) cells carrying a disrupted ALAS-E gene and examined the effect of the lack of ALAS-E gene expression on erythroid differentiation. We found that mRNAs for erythroid transcription factors and TER119-positive cells were increased similarly both in the wild-type and mutant cells. In contrast, heme content, the number of benzidine-positive cells, adult globin protein, and mRNA for beta-major globin were significantly decreased in the mutant cells. These results were confirmed using another ES differentiation system in vitro and suggest that ALAS-E expression, hence heme supply, is critical for the late stage of erythroid cell differentiation, which involves hemoglobin synthesis.
Harigae
H
H
Rockefeller University, New York, NY 10021, USA.
Suwabe
N
N
Weinstock
P H
PH
Nagai
M
M
Fujita
H
H
Yamamoto
M
M
Sassa
S
S
D000624:5-Aminolevulinate Synthetase / Q000172:deficiency* / Q000235:genetics; D000818:Animals; D001560:Benzidines; D002454:Cell Differentiation; D004396:Coloring Agents; D004622:Embryo, Mammalian; D004912:Erythrocytes / Q000201:enzymology*; D015870:Gene Expression; D018390:Gene Targeting; D005822:Genetic Vectors; D005914:Globins / Q000096:biosynthesis* / Q000235:genetics; D006418:Heme / Q000096:biosynthesis*; D051379:Mice; D009154:Mutation; D012333:RNA, Messenger / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism*
D001560:Benzidines; D004396:Coloring Agents; D012333:RNA, Messenger; C029876:benzidine; D006418:Heme; D005914:Globins; D000624:5-Aminolevulinate Synthetase