Inability of overexpressed des(1-3)human insulin-like growth factor I (IGF-I) to inhibit forced mammary gland involution is associated with decreased expression of IGF signaling molecules

D. L. Hadsell, T. Alexeenko, Yann C Klimentidis, D. Torres, A. V. Lee

Research output: Contribution to journalArticle

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Abstract

Overexpression of des(1-3) human insulin-like growth factor I (IGF-I) in the mammary glands of transgenic mice (WAP-DES) inhibits apoptosis during natural, but not forced, mammary involution. We hypothesized that this differential response would correlate with the expression of IGF signal transducers. Forced and natural involution were analyzed in nontransgenic and WAP-DES mice beginning on day 16 postpartum. During natural involution, mammary gland wet weight was higher and apoptosis was lower in WAP-DES than in nontransgenic mice. The WAP-DES transgene had no effect on these parameters during forced involution. Mammary tissue concentrations of the transgene protein were 2- to 10-fold higher than those of endogenous IGF-I. Western blot analysis of pooled mammary tissue extracts demonstrated only slightly higher phosphorylation of the IGF signal transducers insulin receptor substrate-1 (IRS-1) and Akt in the WAP-DES than in nontransgenic mice. Dramatic early reductions in phospho-IRS-1, phospho-Akt, IRS-1, IRS-2, and Akt proteins occurred during forced, but not natural, involution. The abundance of the IGF-I receptor and the messenger RNAs for the IGF-I receptors, IRS-1 and -2, were not affected by either genotype or involution. These findings support the conclusions that mammary cells lose their responsiveness to insulin-like signals during forced involution, and that posttranscriptional or posttranslational regulation of IRS-1 and IRS-2 may play a role in this loss.

Original languageEnglish (US)
Pages (from-to)1479-1488
Number of pages10
JournalEndocrinology
Volume142
Issue number4
DOIs
StatePublished - 2001
Externally publishedYes

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Insulin Receptor Substrate Proteins
Human Mammary Glands
Insulin-Like Growth Factor I
Breast
IGF Type 1 Receptor
Transducers
Transgenes
Apoptosis
Tissue Extracts
Postpartum Period
Transgenic Mice
Proteins
Western Blotting
Genotype
Phosphorylation
Insulin
Weights and Measures
Messenger RNA

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Inability of overexpressed des(1-3)human insulin-like growth factor I (IGF-I) to inhibit forced mammary gland involution is associated with decreased expression of IGF signaling molecules. / Hadsell, D. L.; Alexeenko, T.; Klimentidis, Yann C; Torres, D.; Lee, A. V.

In: Endocrinology, Vol. 142, No. 4, 2001, p. 1479-1488.

Research output: Contribution to journalArticle

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