B rain D erived N eurotrophic F actor

Monoamine Steroid Neuropeptide -Norepinephrine -Testosterone -Neuropeptide Y -Serotonin -Estrogen -Hypocretin -Dopamine -Corticosterone -BDNF

What does it do? Similar to a neurotransmitter Secreted by cells Acts on receptors Binding causes changes in the cell Autocrine Paracrine Receptor Cell BDNF

Where is it? Definitely in brain and CNS Small levels in systemic circulation Hormone action? Receptors in Heart Lungs Kidney

Advice from Dr. Amelia Eisch GOOD!!! Increase BDNF BAD  Decrease BDNF

BDNF BDNF Chronic Stress Affective Disorders Exercise Learning Relaxation

Dendritic Branching… Control BDNF added

Cycle (Unlikely that synaptic activity is the only catalyst) Synaptic firing Ca+ enters cell NMDA + L-VSCC (number of non-Ca2+ mechanisms involved) BDNF produced and released Sustained BDNF activity strengthens synapses and promotes neuronal growth

BDNF signaling Activates genes that turn on LTP systems Enhance trafficking and cytoskeletal structure Actin polymerazation Results in the increased branching and spine density Brings in new AMPA subunits to existing synapses

The Gene – Many mRNAs, One protein Promoters, alternative splicing, polyadenylation sites 18 mRNAs Different strands go different places – regulation @ the mRNA level Greer & Greenberg 08’ Aid et al. 07’

Pruunsild et al. 07’

Don’t drown in promoters! Just remember I & IV (activity dependent)

Epigenetics ‘the study of heritable changes in genome function that occur without a change in DNA sequence‘ “DNA is just a tape carrying information, and a tape is no good without a player. Epigenetics is about the tape player.” http://epigenome.eu/en/1,1,0

Histone Gene Activated Gene Repressed Acetyl groups Methyl groups Histone Acetyltransferase (HAT) Histone Deacetylase (HDAC) Acetyl groups Gene Activated Histone Gene Repressed Methyl groups Histone Methyltransferase (HMT) Histone Demethylase (HDM)

Feng Tian, Ann M. Marini, Robert H. Lipsky NMDA receptor activation induces differential epigenetic modification of BDNF promoters in hippocampal neurons Feng Tian, Ann M. Marini, Robert H. Lipsky

Methods Hippocampal cell cultures monitored for gene expression of BDNF promoters I & IV (mRNA and DNA) Primary sources of activating Ca2+ for BDNF gene are NMDA + L-type Voltage Sensitive Calcium Channels This work uses NMDA activity to induce BDNF transcription NOT L-VSCC

Two repressors of BDNF translation MeCP2 Anchors other repressor enzymes to histone HDAC1 Removes acetyl groups from histone MEF2 recruits

MeCP2 HDAC1

NMDA = exon 1 L-VSCC = exon 4 Cells treated with NMDA over time NMDA = exon 1 L-VSCC = exon 4

Histone Deacetylase (HDAC) Peaked @ 250 nM Gene Activated Acetyl groups Histone Deacetylase (HDAC) Cells treated with different HDAC inhibitor concentrations

DNA Antibody BOOM!!! Segment on interest TF Amplify & run on gel Glass Bead

Time Post NMDA treatment Exon I HDAC1 Exon IV 2 sites @ Exon I 1 site @ Exon IV

MeCP2 Slow action at Exon 1 Exon 2 acted faster. Start with less?

Conclusions Promoters I + IV respond differentially to signals affecting chromatin structure Same signal may act differently MeCP2 is temporally different While NMDA strongly activates Exon 1 realitive to Exon 4, L-VSCC activation would have been interesting