B

D

N

F

rain

erived

eurotrophic

actor

Monoamine

Steroid

Neuropeptide

-Norepinephrine-Serotonin-Dopamine

-Testosterone-Estrogen-Corticosterone

-Neuropeptide Y

-Hypocretin-BDNF

What does it do?Similar to a neurotransmitter

Secreted by cellsActs on receptorsBinding causes changes in the cell

Autocrine

Paracrine

Receptor

BDNF

Cell

Where is it?Definitely in brain and CNSSmall levels in systemic circulation

Hormone action?Receptors in

HeartLungsKidney

Advice from Dr. Amelia Eisch

Increase BDNF

Decrease BDNF

BDNF

BDNF

Control BDNF added

Dendritic Branching…

Synaptic firing

Ca+ enters cell

BDNF produced and released

Sustained BDNF activity strengthens synapses and promotes neuronal growth

(Unlikely that synaptic activity is the only catalyst)

NMDA + L-VSCC(number of non-Ca2+ mechanisms

involved)

BDNF signalingActivates 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

Methyl groups

Acetyl groups

Histone Deacetylase

(HDAC)

Histone Demethylase

(HDM)

Histone Acetyltransfer

ase (HAT)

Histone Methyltransfer

ase (HMT)

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

MeCP2

HDAC1

•Removes acetyl groups from histone•MEF2 recruits

•Anchors other repressor enzymes to histone

HDAC1

MeCP2

NMDA = exon 1 L-VSCC = exon 4

Cells treated with NMDA over time

Cells treated with different HDAC inhibitor concentrations

Acetyl groups

Histone Deacetylase

(HDAC)

Peaked @ 250 nM

Glass Bead

Antibody T

F

DNA

Segment on interestAmplify & run on gel

BOOM!!!

2 sites @ Exon I1 site @ Exon IV

Exo

n

IE

xon

IV

HDAC1

Time Post NMDA treatment

MeCP2

Slow action at Exon 1

Exon 2 acted faster. Start with less?

ConclusionsPromoters I + IV respond differentially to

signals affecting chromatin structureSame signal may act differentlyMeCP2 is temporally different

While NMDA strongly activates Exon 1 realitive to Exon 4, L-VSCC activation would have been interesting