Parallel fiber(PF) Climbing fiber(CF) Purkinje cell Granule cell Neural Circuit of Cerebellar Cortex.

Presentation on theme: "Parallel fiber(PF) Climbing fiber(CF) Purkinje cell Granule cell Neural Circuit of Cerebellar Cortex."— Presentation transcript:

1 Parallel fiber(PF) Climbing fiber(CF) Purkinje cell Granule cell Neural Circuit of Cerebellar Cortex

2 小脳長期抑圧のシミュレーション NO Glu AMPA-RVGCCmGluR Gq PLC PKC DAGIP 3 Ca 2+ Store IP 3 R PLA 2 MAPK MEK Raf AA GC Ca 2+ CRHR cGMP PKG G-substrate PP2A Lyn CF PF Positive Feedback Loop CRF

3 小脳と教師あり学習 登上線維 CF 平行線維 PF プルキンエ 細胞 1. プルキンエ細胞は教師あ り学習 2. PF が文脈情報、 CF が誤差 情報 3. PF が間違った出力をする と、 CF が誤差信号を送り、 シナプス荷重を減少させる （長期抑圧、 LTD ）

4 小脳 LTD のシグナル伝達 登上線維 平行線維 スパイン 平行線維（ PF ）と 登上線維（ CF ）が ある時間幅内で入力 スパイン内 Ca 2+ ↑ 平行線維入力を受け取る AMPA 受容体の個数 PKC

5 シグナル伝達が実現すべきこと 1. 平行線維（ PF ）と登上線維（ CF ）の両方入 力のみ Ca 2+ 上昇が起こる 2. PF 入力よりも後の CF 入力を検出する（誤差 は出力した後でないと計算できない ） 3. Ca 2+ 上昇のあと長時間 LTD を持続させる

6 Motivations of Systems Biology Simulation Most cerebellar learning theories (including Ito’s) require PF-CF temporal window for plasticity (STDP). But, some experiments (photolysis, strong PF stimulation) are against this temporal window. Then, biological significance of LTD? How altered synaptic efficacy can be maintained in medium term (several tens of minutes)?

7 PF と CF の両方で Ca 2+ 上昇 Wang et al., (2000) Nat Neurosci

8 Temporal Window of PF and CF Inputs for Ca 2+ Firing and LTD Wang et al., (2000) Nat Neurosci 3, 1266-1273

9 IP 3 受容体の性質 1. IP 3 R が開くには IP 3 と Ca 2+ の両方が必 要 2. Ca 2+ が多すぎると閉じる Open Probability Bezprozvanny et al., Nature(1991)

10 A New Model of IP3R based on Adkins and Taylor Four-States Model

11 Ca 2+ 上昇の分子メカニズム mGluRAMPA-RVGCC Glu PLC DAG Gq Ca 2+ Ca 2+ Store PF CF IP 3 IP 3 R

12 CF 入力 mGluRAMPA-R Glu PLC DAG Gq Ca 2+ Store PF CF IP 3 IP 3 R VGCC Ca 2+ VGCC

13 PF 入力 AMPA-R 経路 mGluR PLC DAG Gq Ca 2+ Store PF CF IP 3 IP 3 R AMPA-RVGCC Glu Ca 2+ AMPA-RVGCC Glu Ca 2+

14 PF 入力 mGluR 経路 AMPA-RVGCC Ca 2+ Store PF CF mGluR Glu PLC DAG Gq Ca 2+ IP 3 IP 3 R mGluR Glu PLC Gq Ca 2+ DAG IP 3 IP 3 R

15 PF の IP 3 産生遅延が CF を待つ Ca 2+ Ca 2+ Store PF CF IP 3 Δ IP 3 R Positive Feedback Loop AMPA-R 経路 mGluR 経路

16 「 PF と CF 同時」の場合 Ca 2+ Store PF CF IP 3 Δ IP 3 R Positive Feedback Loop Ca 2+ AMPA-R 経路 mGluR 経路

17 「 PF と CF 同時」の場合 Ca 2+ Ca 2+ Store PF CF Δ IP 3 R Positive Feedback Loop IP 3 AMPA-R 経路 mGluR 経路

18 「 PF 後 CF 」の場合 Ca 2+ Store PF CF IP 3 Δ IP 3 R Positive Feedback Loop Ca 2+ AMPA-R 経路 mGluR 経路

19 「 PF 後 CF 」の場合 Ca 2+ Store PF CF Δ Ca 2+ IP 3 IP 3 R Positive Feedback Loop IP 3 R Ca 2+ IP 3 Positive Feedback Loop AMPA-R 経路 mGluR 経路

20 シグナル伝達モデルの作成 mGluRAMPA-RVGCC Glu PLC DAG Gq Ca 2+ Ca 2+ pump Ca 2+ Store PF CF Ca 2+ pump Leak Na + /Ca 2+ exchanger Ca 2+ Buffer Proteins IP 3 IP 3 R IP 3 enzyme

21 Signal Transduction Pathways of Supralinear Ca 2+ Increase

22 Simulation of Supralinear Ca 2+ Increase GENESIS simulator with Kinetikit interface developed by Upi Bhalla Ordinary differential equations for molecule- molecule and enzymatic reactions 49 variables and 95 parameters 20 initial concentrations with 3 assumed 25 dissociation constants and Michaelis constants with 3 assumed 9 maximum enzyme velocities with 3 assumed

23 例 :Glu→mGluR→Gq GlumGluR Gq

24 化学反応速度論 生化学反応 (1) 分子間相互作用 [A]+[B] [AB] KfKf KbKb d[A]/dt = － K f [A][B] + K b [AB] [A] + [AB] = [A all] = const. 解離定数 K d =K b /K f ：平衡状態での生成物の割合 時定数 τ =1/(K f +K b ) ：平衡状態に向かう速さ

25 化学反応速度論 (2) 酵素反応 (Michaelis-Menten) [E]+[S][ES][E]+[P] KfKf KbKb K cat E:Enzyme, S:Substrate, P:Product 生化学反応 (1) 分子間相互作用 [A]+[B] [AB] KfKf KbKb

26

27 Supralinear Ca 2+ Increase is dependent on PF and CF Timing

28 Temporal Window of Ca 2+ Firing: Coincidence Detection of PF and CF Ca 2+ IP 3

29 Ca 2+ Dynamics explains Three Different Forms of LTD

30 Time Delay by IP 3 Slow Increase and Coincidence Detection by IP 3 R

31 線維入力から LTD まで

32 Na/Ca mGlu R 平行線維のみでは不十分 Positive feedback loop PKC PLC Raf cGMP Na/Ca Lyn AMPA R Gq GC mGlu R membrane NO MAP kinasePLA2 G substrate 平行線維 Glutamate AA PP2A MEK [ Ca 2+ ] DAG IP PKG 3 AMPA R Ica CRHR

33 登上線維のみでは不十分 登上線維 AMPA R Glutamate PLC DAG AA Lyn PLA2 IP 3 [ Ca 2+ ] Raf Gq Positive feedback loop PP2A GC PKG cGMP G substrate PKC Na/Ca mGlu R CRF membrane NO MEK MAP kinase 平行線維 CRHR Ica

34 NO AMPA R Glutamate [ Ca MEK Na/Ca AA MAP kinase Lyn PLA2 IP 3 Raf Gq Ica Positive feedback loop PKC CRHR GC PKG cGMP mGlu R CRF membrane 平行線維と登上線維の両方が必要 Na/Ca mGlu R AMPA R PKC Raf MAP kinasePLA2 AA MEK PLC Ica 2+ ] PP2A AA PKC Raf PLA2MAP kinase G substrate PP2A PLC [ Ca 2+ ] DAG IP PKG 3 [ Ca 2+ ] CRF NO Glutamate 登上線維 平行線維 登上線維 平行線維 MEK AMPA R cGMP Na/Ca Lyn Gq GC mGlu R CRHR Ica AMPA R

35 Stimulus 1Hz for 5min AMPA receptor (  M) 0102030405060708090100 0 0.1 0.2 0.3 0.4 0.5 Time (min) Phosphorylated AMPA Receptors Non-Phosphorylated AMPA Receptors 長期抑圧（ LTD ）の再現 登上線維 平行線維 EPSP (%) 0 20 40 60 80 100 PP

36 AMPA-R 上流のシグナル解析 AMPA receptor Concentration (  M) 0102030405060708090100 0 0.1 0.2 0.3 0.4 0.5 Time (min) EPSP (%) 0 20 40 60 80 100 AMPA-R PKC PP2A 0102030405060708090100 Time (min) 0 0.05 0.10 0.15 PKC concentration (  M) P PP

37 はじめは Ca 2+ と DAG が PKC を活性化 AMPA receptor Concentration (  M) 0102030405060708090100 0 0.1 0.2 0.3 0.4 0.5 Time (min) EPSP (%) 0 20 40 60 80 100 AMPA-R PKC PP2A P DAG Ca 2+ 0102030405060708090100 Time (min) 0 0.05 0.10 0.15 PKC concentration (  M)

38 遅れて AA が PKC を活性化する AMPA receptor Concentration (  M) 0102030405060708090100 0 0.1 0.2 0.3 0.4 0.5 Time (min) EPSP (%) 0 20 40 60 80 100 DAGAA Ca 2+ 0102030405060708090100 Time (min) 0 0.05 0.10 0.15 PKC concentration (  M) AMPA-R PKC PP2A P

39 PP2A は抑制され続けている AMPA receptor Concentration (  M) 0102030405060708090100 0 0.1 0.2 0.3 0.4 0.5 Time (min) EPSP (%) 0 20 40 60 80 100 0102030405060708090100 Time (min) 0 1 2 3 PP2A concentration (  M) DAGAA Ca 2+ 0102030405060708090100 Time (min) 0 0.05 0.10 0.15 PKC concentration (  M) AMPA-R PKC PP2A P

40 LTD には十分量の Ca 2+ が必要 Phosphorylated AMPA receptor  M) 0 0.1 0.2 0.3 020406080100 Time (min) PF + CF PF alone CF alone 0 1.0 2.0 3.0 Active PP2A (  M) 020406080100 Time (min) PF + CF PF alone CF alone 0 0.05 0.1 Active PKC (  M) 020406080100 Time (min) PF + CF PF alone CF alone

41 経路遮断実験の再現 Simulation data 0102030405060708090100 0 0.1 0.2 0.3 Time (min) AMPA phosphorylation (  M) Deleted pathways control

42 PKC 阻害の再現 Simulation data 0102030405060708090100 0 0.1 0.2 0.3 Time (min) AMPA phosphorylation (  M) control PKC Block Deleted pathways

43 NO は LTD に必要 Simulation data 0102030405060708090100 0 0.1 0.2 0.3 Time (min) AMPA phosphorylation (  M) NO Block Deleted pathways control

44 Ca 2+ キレート実験の再現 Simulation data 0102030405060708090100 0 0.1 0.2 0.3 Time (min) AMPA phosphorylation (  M) Deleted pathways control Chelate Ca 2+

45 MAPK カスケードは LTD を保持する Simulation data 0102030405060708090100 0 0.1 0.2 0.3 Time (min) AMPA phosphorylation (  M) Block MAP kinase Deleted pathways control