| Abstract No.: | A-A1020 |
| Country: | Canada |
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| Title: | ROLE OF MBD2 AND NGFI-A IN PROGRAMMING GLUCOCORTICOID RECEPTOR EXPRESSION IN A MODEL OF MATERNAL CARE. |
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| Authors/Affiliations: | 2 Ian C. Hellstrom*; 1 Stephen D. Andrews; 1 Marilyne Blaine; 2 Josie Diorio; 1 Moshe Szyf; 2 Michael J. Meaney;
1 Dept. Pharacology & Therapeutics, McGill University, Montreal, QC, Canada; 2 Douglas Institute, McGill University, Montreal, QC, Canada
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| Content: | Naturally-occurring differences in the key environmental factor for neonatal rats - maternal care - has previously been shown by our lab to be an important determinant of both behavior and gene expression in adult offspring. Higher frequencies of maternal licking and grooming behavior during the first six days of life correlates with increased expression of glucocorticoid receptor (GR) in the hippocampus of offspring, accompanied by diminished corticosterone response to stress (e.g. Weaver et al., 2004). Further work has suggested that the transcription factor NGFI-A and the putative demethylase MBD2 may be involved in this programming of gene expression by early life environment (Weaver et al., 2007). In the current study, we build on results showing increases in GR binding in primary hippocampal cultures by serotonin (5-HT) treatment (Mitchell et al., 1992) by investigating the roles of NGFI-A and MBD2 in the induction of GR expression in vitro.
Objectives: 1. Show that hippocampal GR expression is induced by 5-HT, and that knockdown of either MBD2 or NGFI-A prevents this induction.
2. Establish whether NGFI-A or MBD2 alone can induce GR expression.
Materials & Methods: Primary hippocampal cultures were prepared from 19-day-old embryos. These cultures were infected with lentiviral vectors expressing either NGFI-A, MBD2, or an siRNA targeting NGFI-A or MBD2. Cells were harvested, RNA extracted, and qRT-PCR was then performed to examine levels of gene expression.
Results: We show that treatment of primary hippocampal cultures with 5-HT significantly induces MBD2, NGFI-A, and total GR. When MBD2 or NGFI-A are knocked down by siRNA, their induction by 5-HT is blocked, as is the induction of GR. Overexpression of NGFI-A alone also significantly induces GR expression. Additional data on the effect of MBD2 overexpression on GR induction will also be presented.
Conclusion: From these results, it is seen that 5-HT induces the expression of GR in hippocampal neurons, and that both NGFI-A and MBD2 are necessary and sufficient for this induction. This indicates that the same proteins are likely to be involved in the programming of GR expression by maternal care. Further work will address this hypothesis.
Work supported by CIHR, HFSP
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