LAP proteins are localized at the post-synaptic membrane of neuromuscular junctions and appear to modulate synaptic morphology and transmission.
Erbin, Lano, Scribble, and Densin-180 belong to LAP (leucine-rich repeats and PDZ domain) adaptor proteins involved in cell signaling pathways. Previously, we identified Erbin, Lano, and Scribble, but not Densin-180, in muscle cells, where they are involved in regulating the aggregation of nicotinic acetylcholine receptors in vitro. Here, we analyzed their cellular localization at the neuromuscular junction (NMJ) in skeletal muscles of mice. Erbin, Lano, and Scribble were significantly accumulated at NMJs and localized in different synaptic cells. Moreover, we used mouse mutants to analyze the role of Erbin at the NMJ. We used two Erbin mutant mouse strains that either completely lack Erbin protein (Erbinnull/null) or express a truncated Erbin mutant where the carboxy-terminal PDZ domain is replaced by β-galactosidase (ErbinΔC/ΔC) thereby abolishing its interaction with ErbB receptor tyrosine kinases. Neither the lack of the PDZ domain of Erbin, nor its complete absence interfered with the general localization of LAP proteins at NMJs, but Lano and Scribble transcript levels were up-regulated in homozygous Erbin-null muscles. Furthermore, grip strength was reduced and neural transmission impaired in homozygous aged Erbin-null but not Erbin-ΔC mice. Erbin-null skeletal muscles did not reveal any conspicuous impairment of the muscle fiber. Localization of other NMJ marker proteins was not affected either. Quantitative 3D morphometry showed that NMJs of Erbin-null muscles were significantly smaller and fragmented in the soleus. We speculate that Erbin, Lano, and Scribble act at the post-synaptic membrane of NMJs in a concerted fashion to regulate nicotinic acetylcholine receptors cluster morphology and neural transmission. Cover Image for this issue: doi: 10.1111/jnc.13340.
Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Bojana
B
Kravic
Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Danyil
D
Huraskin
Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Alexander D
AD
Frick
Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Jasmin
J
Jung
Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Veronika
V
Redai
Optical Imaging Center Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Ralf
R
Palmisano
CRCM, Cell Polarity, Cell signaling and Cancer "Equipe labellisée Ligue Contre le Cancer", Inserm, U1068, Marseille, France.|Institut Paoli-Calmettes, Marseille, France.|Aix-Marseille Université, Marseille, France.|CNRS, UMR7258, Marseille, France.
Sylvie
S
Marchetto
CRCM, Cell Polarity, Cell signaling and Cancer "Equipe labellisée Ligue Contre le Cancer", Inserm, U1068, Marseille, France.|Institut Paoli-Calmettes, Marseille, France.|Aix-Marseille Université, Marseille, France.|CNRS, UMR7258, Marseille, France.
Jean-Paul
JP
Borg
Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia, USA.
Lin
L
Mei
Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany. said.hashemolhosseini@fau.de.
Said
S
Hashemolhosseini
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000090263:Leucine-Rich Repeat Proteins; D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018485:Muscle Fibers, Skeletal / Q000502:physiology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000294:innervation; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins; D009469:Neuromuscular Junction / Q000502:physiology* / Q000648:ultrastructure; D054731:PDZ Domains / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D013569:Synapses / Q000648:ultrastructure*; D013570:Synaptic Membranes / Q000378:metabolism*; D009435:Synaptic Transmission / Q000235:genetics* / Q000502:physiology*
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D000090263:Leucine-Rich Repeat Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D011506:Proteins; C498804:Erbb2ip protein, mouse; C101671:Lrig1 protein, mouse; C508433:scrib protein, mouse
Erbin; Lano; Scribble; neuromuscular junction; nicotinic acetylcholine receptor