Post on 04-Jan-2016
description
ARMS interacts with ARMS interacts with -syntrophin: -syntrophin: implications for EphA4 signaling at the implications for EphA4 signaling at the
neuromuscular synapseneuromuscular synapse
Yu CHENYu CHEN
Department of BiochemistryDepartment of Biochemistry
Hong Kong University of Science and TechnologyHong Kong University of Science and Technology
Sub-synapticnucleus
Schwann cell
Neurotransmitterreceptor
Pre-synaptic Motor Neuron
Post-synapticMuscle
Pre-synaptic Neuron
Post-synaptic Neuron
AcetylcholinereceptorNeurotransmitter
Acetylcholine
Ion Influx
CNS synapse Neuromuscular junctionCNS synapse Neuromuscular junction
Axon & dendritic growth
Axon guidance and neuronal migration
Neuronal survival and differentiation
Synapse formation and plasticity
Nerve regeneration
Functions of receptor tyrosine kinasesFunctions of receptor tyrosine kinasesFunctions of receptor tyrosine kinasesFunctions of receptor tyrosine kinases
Plasma membrane
Nucleus
RTK
P
Trophic factors
Raf
MEK
ERK
ERK
c-Fos
Elk-1
BDNF
TrkB
Ephrin
EphA4
AChR clustering and NMJ stability Development/maturation of NMJ
Muscle fiber
ARMS (ARMS (aankyrin nkyrin rrepeat- rich epeat- rich mmembrane embrane sspanninpannin
gg))
● Activation of Eph receptor results in the rapid tyrosine phosphorylation of ARMS (Kong et al.,2001)
● ARMS interacts with TrkB and potentiates TrkB-mediated sustained MAPK activation (Arévalo et al.,2004)
ARMS localized at the neuromuscular junctionARMS localized at the neuromuscular junction
ARMS colocalized with EphA4 and TrkB at the NMJARMS colocalized with EphA4 and TrkB at the NMJ
Library screening for ARMS interacting proteinsLibrary screening for ARMS interacting proteins
Bait: C-terminal 100 amino acids of ARMSBait: C-terminal 100 amino acids of ARMS
Library: P12 mouse muscle cDNA libraryLibrary: P12 mouse muscle cDNA library
EERESIL
1616 1715
PH1a PDZ PH1b PH2 SU
PH1a PDZ PH1b PH2 SU
GI->AA
-syntrophin
-syntrophin mutant
ARMS
+
―
ARMS interacted with ARMS interacted with -syntrophin-syntrophin
ARMS and syntrophin colocalized in muscleARMS and syntrophin colocalized in muscle
ARMS PDZ binding motif and ARMS PDZ binding motif and -syntrophin PDZ do-syntrophin PDZ domain were necessary for ARMS clusteringmain were necessary for ARMS clustering
Muscle fiber
Ephrin
EphA4ARMS
Syn
?
ARMS interacted with EphA4 receptorARMS interacted with EphA4 receptor
Muscle fiber
Ephrin
STAT
Subsynaptic gene transcription
EphA4ARMS
Syn
JAK JAK?
?
ARMS and ARMS and -syntrophin potentiates EphA4--syntrophin potentiates EphA4-mediated signalingmediated signaling
Ephrin
STAT
Subsynaptic gene transcription
EphA4ARMS
Syn
JAK JAK
? ?Muscle fiber
Junctional localization of ARMS was Junctional localization of ARMS was aberrant in syntrophin knockout miceaberrant in syntrophin knockout mice
Junctional localization of EphA4 was Junctional localization of EphA4 was aberrant in syntrophin knockout miceaberrant in syntrophin knockout mice
Ephrin
STAT
Subsynaptic gene transcription
EphA4ARMS
Syn
JAK JAK Muscle fiber