Indispensable function for embryogenesis, expression and regulation of the nonspecific form of the 5-aminolevulinate synthase gene in mouse.
The first step of heme biosynthesis in animals is catalyzed by 5-aminolevulinate synthase (ALAS), which controls heme supply in various tissues. To clarify the roles that the nonspecific isoform of ALAS (ALAS-N) plays in vivo, we prepared a green fluorescent protein (GFP) knock-in mouse line in which the Alas1 gene (encoding ALAS-N) is replaced with a gfp gene. We found that mice bearing a homozygous knock-in allele (Alas1(GFP/GFP)) were lethal by embryonic day 8.5, demonstrating that ALAS-N is essential for early embryogenesis. Fluorescence microscopic and flow cytometric analyses of heterozygous mouse (Alas1(+/GFP)) tissues showed that the Alas1 expression level differs substantially in tissues; Alas1 is highly expressed in testis Leydig cells, exocrine glands (including submandibular and parotid glands), endocrine glands (such as adrenal and thyroid glands) and hematopoietic lineage cells (including neutrophils and eosinophils). Quantitative analyses of GFP mRNA and ALAS-N mRNA in various tissues of Alas1(+/GFP) mice suggested that the destabilization of ALAS-N mRNA was not uniform in the various tissues. These results thus lay bare that elaborate control of the endogenous heme supply operates in various mouse tissues through regulation of the ALAS-N expression level and that this control is essential for heme homeostasis in animals.
Okano
Satoshi
S
Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Japan.
Zhou
Lingyun
L
Kusaka
Toshimasa
T
Shibata
Kazuhide
K
Shimizu
Kazuhiro
K
Gao
Xu
X
Kikuchi
Yuko
Y
Togashi
Yoshiyuki
Y
Hosoya
Tomonori
T
Takahashi
Satoru
S
Nakajima
Osamu
O
Yamamoto
Masayuki
M
D000624:5-Aminolevulinate Synthetase / Q000235:genetics* / Q000378:metabolism; D000375:Aging / Q000235:genetics; D000818:Animals; D019070:Cell Lineage / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics; D020964:Embryo Loss / Q000201:enzymology; D004622:Embryo, Mammalian / Q000201:enzymology / Q000473:pathology; D047108:Embryonic Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D055879:Gene Knock-In Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006413:Hematopoietic System / Q000166:cytology / Q000378:metabolism; D006579:Heterozygote; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009928:Organ Specificity / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D007527:Isoenzymes; D012333:RNA, Messenger; D049452:Green Fluorescent Proteins; D000624:5-Aminolevulinate Synthetase