Organ-specific and age-dependent expression of insulin-like growth factor-I (IGF-I) mRNA variants: IGF-IA and IB mRNAs in the mouse

Takashi Ohtsuki, Mariko Otsuki, Yousuke Murakami, Tetsuya Maekawa, Takashi Yamamoto, Koji Akasaka, Sakae Takeuchi, Sumio Takahashi

Research output: Contribution to journalArticle

20 Citations (Scopus)

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-17β (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.

Original languageEnglish
Pages (from-to)1011-1021
Number of pages11
JournalZoological Science
Volume22
Issue number9
DOIs
Publication statusPublished - Sep 2005

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Keywords

  • Estradiol
  • Insulin like growth factor-I (IGF-I)
  • Mouse
  • Uterus

ASJC Scopus subject areas

  • Animal Science and Zoology

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