TY - JOUR
T1 - Overexpressed Monomeric Human Acetylcholinesterase Induces Subtle Ultrastructural Modifications in Developing Neuromuscular Junctions of Xenopus laevis Embryos
AU - Seidman, Shlomo
AU - Aziz‐Aloya, Revital Ben
AU - Timberg, Rina
AU - Loewenstein, Yael
AU - Velan, Baruch
AU - Shafferman, Avigdor
AU - Liao, Jian
AU - Norgaard‐Pedersen, Bent
AU - Brodbeck, Urs
AU - Soreq, Hermona
PY - 1994/5
Y1 - 1994/5
N2 - Abstract: Formation of a functional neuromuscular junction (NMJ) involves the biosynthesis and transport of numerous muscle‐specific proteins, among them the acetylcholine‐hydrolyzing enzyme acetylcholinesterase (AChE). To study the mechanisms underlying this process, we have expressed DMA encoding human AChE downstream of the cytomegalovirus promoter in oocytes and developing embryos of Xenopus laevis. Recombinant human AChE (rHAChE) produced in Xenopus was biochemically and immunochemically indistinguishable from native human AChE but clearly distinguished from the endogenous frog enzyme. In microinjected embryos, high levels of catalytically active rHAChE induced a transient state of over‐expression that persisted for at least 4 days postfertilization. rHAChE appeared exclusively as nonassembled monomers in embryos at times when endogenous Xenopus AChE displayed complex oligomeric assembly. Nonetheless, cell‐associated rHAChE accumulated in myotomes of 2‐and 3‐day‐old embryos within the same sub‐cellular compartments as native Xenopus AChE. NMJs from 3‐day‐old DNA‐injected embryos displayed fourfold or greater overexpression of AChE, a 30% increase in postsynaptic membrane length, and increased folding of the postsynaptic membrane. These findings indicate that an evolutionarily conserved property directs the intracellular trafficking and synaptic targeting of AChE in muscle and support a role for AChE in vertebrate synaptogenesis.
AB - Abstract: Formation of a functional neuromuscular junction (NMJ) involves the biosynthesis and transport of numerous muscle‐specific proteins, among them the acetylcholine‐hydrolyzing enzyme acetylcholinesterase (AChE). To study the mechanisms underlying this process, we have expressed DMA encoding human AChE downstream of the cytomegalovirus promoter in oocytes and developing embryos of Xenopus laevis. Recombinant human AChE (rHAChE) produced in Xenopus was biochemically and immunochemically indistinguishable from native human AChE but clearly distinguished from the endogenous frog enzyme. In microinjected embryos, high levels of catalytically active rHAChE induced a transient state of over‐expression that persisted for at least 4 days postfertilization. rHAChE appeared exclusively as nonassembled monomers in embryos at times when endogenous Xenopus AChE displayed complex oligomeric assembly. Nonetheless, cell‐associated rHAChE accumulated in myotomes of 2‐and 3‐day‐old embryos within the same sub‐cellular compartments as native Xenopus AChE. NMJs from 3‐day‐old DNA‐injected embryos displayed fourfold or greater overexpression of AChE, a 30% increase in postsynaptic membrane length, and increased folding of the postsynaptic membrane. These findings indicate that an evolutionarily conserved property directs the intracellular trafficking and synaptic targeting of AChE in muscle and support a role for AChE in vertebrate synaptogenesis.
KW - Human acetylcholinesteras
KW - Neuromuscular junction
KW - Xenopus laevis embryos
KW - ‐Muscle
UR - http://www.scopus.com/inward/record.url?scp=0028325160&partnerID=8YFLogxK
U2 - 10.1046/j.1471-4159.1994.62051670.x
DO - 10.1046/j.1471-4159.1994.62051670.x
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C2 - 8158119
AN - SCOPUS:0028325160
SN - 0022-3042
VL - 62
SP - 1670
EP - 1681
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
IS - 5
ER -