title: Organ-specific and age-dependent expression of insulin-like growth factor-I (IGF-I) mRNA variants: IGF-IA and IB mRNAs in the mouse.
abstract: Insulin-like growth factor-I (IGF-I) gene generates several IGF-I mRNA variants by alternative splicing. Two promoters are present in mouse IGF-I gene. Each promoter encodes two IGF-I mRNA variants (IGF-IA and IGF-IB mRNAs). Variants differ by the presence (IGF-IB) or absence (IGF-IA) of a 52-bp insert in the E domain-coding region. Functional differences among IGF-I mRNAs, and regulatory mechanisms for alternative splicing of IGF-I mRNA are not yet known. We analyzed the expression of mouse IGF-IA and IGF-IB mRNAs using SYBR Green real-time RT-PCR. In the liver, IGF-I mRNA expression increased from 10 days of age to 45 days. In the uterus and ovary, IGF-I mRNA expression increased from 21 days of age, and then decreased at 45 days. In the kidney, IGF-I mRNA expression decreased from 10 days of age. IGF-IA mRNA levels were higher than IGF-IB mRNA levels in all organs examined. Estradiol-17beta (E2) treatment in ovariectomized mice increased uterine IGF-IA and IGF-IB mRNA levels from 3 hr after injection, and highest levels for both mRNAs were detected at 6 hr, and relative increase was greater for IGF-IB mRNA than for IGF-IA mRNA. These results suggest that expression of IGF-I mRNA variants is regulated in organ-specific and age-dependent manners, and estrogen is involved in the change of IGF-I mRNA variant expression.
authors.affiliation: Department of Biology, Faculty of Science, Okayama University, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohtsuki
authors.forename: Mariko
authors.initials: M
authors.lastname: Otsuki
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Murakami
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Maekawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Koji
authors.initials: K
authors.lastname: Akasaka
authors.forename: Sakae
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Sumio
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D000367:Age Factors; D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D017931:DNA Primers; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D009928:Organ Specificity; D010053:Ovary / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000378:metabolism
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D004958:Estradiol; D017526:Receptor, IGF Type 1