The document summarizes a study that investigated DNA methylation patterns of BDNF transcripts during classical conditioning in pond turtles. The study found that exon II methylation increased and exon III methylation decreased after conditioning, corresponding to reduced exon II expression and enhanced exon III expression. Infusion of a DNA methyltransferase inhibitor altered the normal conditioning-related methylation patterns of exons II and III, and also interfered with the typical exon expression changes seen with conditioning. The results indicate that rapid DNA methylation changes play a role in regulating BDNF transcript expression during classical conditioning.

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Presentation Abstract
Program#/Poster#: 706.01/E3
Presentation Title: Differential expression of BDNF transcripts during classical conditioning is regulated by distinct patterns of DNA methylation
Location: Halls B-H
Presentation time: Wednesday, Nov 13, 2013, 8:00 AM - 9:00 AM
Topic: ++B.08.j. Transcription and translation in plasticity
Authors: *G. AMBIGAPATHY, Z. ZHENG, J. KEIFER;
Neurosci Group, Basic Biomed. Sci., Univ. South Dakota Sanford Sch. Med., Vermillion, SD
Abstract: DNA methylation is a crucial mechanism for regulating chromatin remodeling in the nervous system. To investigate the epigenetic
regulatory mechanisms controlling BDNF expression and function in an in vitro model of eyeblink classical conditioning, we
analyzed the methylation levels for the bdnf gene in the pond turtle Trachemys scripta elegans (tBDNF). The turtle BDNF gene
consists of three noncoding 5′ exons (I, II and III) linked with individual promoter regions and one 3′ coding exon (IV). We
analyzed the level of DNA methylation for all three non-coding exons and their promoter regions in naive, pseudoconditioned and
conditioned groups by bisulfite sequencing PCR (BSP). The results show that there were no significant differences in the
methylation level of exon I in all three groups. However, the methylation level was significantly increased for exon II and
decreased for exon III in conditioned animals when compared with naive and pseudoconditioned groups. These changes occurred
within 25 minutes (or one conditioning session). Interestingly, the CREB binding site for exon II was methylated while that for
exon III was demethylated in conditioning. These levels of methylation correspond with reduced expression of exon II tBDNF
transcripts and enhanced expression of exon III transcripts during conditioning.
We also evaluated the effect of a DNA methyltransferase inhibitor zebularine on tBDNF DNA methylation and transcript
expression. Infusion of zebularine significantly altered the conditioning-related pattern of tBDNF DNA methylation for exons II
and III. To examine this effect, tBDNF transcript expression after zebularine infusion in conditioned animals was analyzed by
PCR. The results show that the level of exon II transcript expression was significantly increased above normal levels observed for
conditioning. Moreover, exon III transcript expression was significantly reduced. These findings indicate that zebularine treatment
interfered with the normal pattern DNA methylation and regulation of exon II and III transcript expression in conditioning. The
present study indicates that rapid changes in tBDNF methylation play a major role in the regulation of transcript expression and
classical conditioning.
Disclosures: G. Ambigapathy: None. Z. Zheng: None. J. Keifer: None.
Keyword(s): BDNF
Methylation
Classical conditioning
Support: NIH grant NS 051187
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