Expression of insulin-like growth factor system genes during the early postnatal neurogenesis in the mouse hippocampus.

Abstract

Insulin-like growth factor-1 (IGF-1) is essential to hippocampal neurogenesis and the neuronal response to hypoxia/ischemia injury. IGF (IGF-1 and -2) signaling is mediated primarily by the type 1 IGF receptor (IGF-1R) and modulated by six high-affinity binding proteins (IGFBP) and the type 2 IGF receptor (IGF-2R), collectively termed IGF system proteins. Defining the precise cells that express each is essential to understanding their roles. With the exception of IGFBP-1, we found that mouse hippocampus expresses mRNA for each of these proteins during the first 2 weeks of postnatal life. Compared to postnatal day 14 (P14), mRNA abundance at P5 was higher for IGF-1, IGFBP-2, -3, and -5 (by 71%, 108%, 100%, and 98%, respectively), lower for IGF-2, IGF-2R, and IGFBP-6 (by 65%, 78%, and 44%, respectively), and unchanged for IGF-1R and IGFBP-4. Using laser capture microdissection (LCM), we found that granule neurons and pyramidal neurons exhibited identical patterns of expression of IGF-1, IGF-1R, IGF-2R, IGFBP-2, and -4, but did not express other IGF system genes. We then compared IGF system expression in mature granule neurons and their progenitors. Progenitors exhibited higher mRNA levels of IGF-1 and IGF-1R (by 130% and 86%, respectively), lower levels of IGF-2R (by 72%), and similar levels of IGFBP-4. Our data support a role for IGF in hippocampal neurogenesis and provide evidence that IGF actions are regulated within a defined in vivo milieu.

• Authors: Jihui Zhang, Billie M Moats-Staats, Ping Ye, A Joseph D'Ercole
• Journal: Journal of neuroscience research (J Neurosci Res) Vol. 85 Issue 8 Pg. 1618-27 (Jun 2007) ISSN: 0360-4012 [Print] United States
• PMID: 17455296 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright (c) 2007 Wiley-Liss, Inc.

Chemical References

• Insulin-Like Growth Factor Binding Proteins
• RNA, Messenger
• Receptor, IGF Type 1

Topics

• Animals
• Animals, Newborn
• Gene Expression Regulation, Developmental
• Hippocampus (growth & development, metabolism)
• Insulin-Like Growth Factor Binding Proteins (biosynthesis, genetics)
• Lasers
• Mice
• Mice, Inbred C57BL
• Microdissection
• Neurons (metabolism)
• Pyramidal Cells (metabolism)
• RNA, Messenger (biosynthesis)
• Receptor, IGF Type 1 (biosynthesis, genetics)
• Reverse Transcriptase Polymerase Chain Reaction
• Stem Cells (metabolism)