Rapsyn mediates subsynaptic anchoring of PKA type I and stabilisation of acetylcholine receptor in vivo

Choi, Kyeong-Rok; Berrera, Marco; Reischl, Markus; Strack, S.; Albrizio, Marina; Röder, Ira V.; Wagner, Anika E.; Petersen, Yvonne; Hafner, Mathias; Zaccolo, Manuela; Rudolf, Rüdiger

doi:10.1242/jcs.092361

Cited by 41 publications

(66 citation statements)

References 44 publications

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“…Because NMJ deteriorates in the fast skeletal muscle more severely with ageing than in slow skeletal muscle, while PKA RIα plays a key role in nAChR stabilization at the NMJ postsynaptic membrane,12, 15 we postulate that the amount of PKA RIα at the NMJ will decrease with ageing and possibly mainly in the fast skeletal muscles. To test this, we first performed double immunofluorescence staining of PKA RIα and NMJ in SOL and TA muscle cryosections from young and old mice.…”

Section: Resultsmentioning

confidence: 94%

“…Therefore, it is important to determine the subcellular localization of cTnT in the skeletal muscle for a better understanding of its potential biological role in old skeletal muscle. Given that cTnT functions as a D‐AKAP that interacts with PKA RI and RII regulatory subunits,10 both of which are enriched at the NMJ in skeletal muscle,11, 12, 13, 14, 15 we next wanted to determine if cTnT is also localized at the NMJ. To test this, we performed double immunofluorescence staining using 1C11 anti‐cTnT antibody to label endogenous cTnT and Alexa 568‐conjugated α‐bungarotoxin to label nicotinic acetylcholine receptors (nAChRs) at the postsynaptic NMJ membrane.…”

Section: Resultsmentioning

confidence: 99%

“…Because rapsyn mediates subsynaptic anchoring of PKA type I and stabilization of nAChR in vivo, 15 we also compared rapsyn enrichment at the NMJ between young and old TA muscles; it was highly enriched at the NMJ in both old and young samples (Supporting Information Figure S6 ). We next analysed PKA RIIα at the NMJ.…”

Section: Resultsmentioning

confidence: 99%

“…Although PKA RIα, RIIα, and RIIβ are all localized at the postsynaptic neuromuscular junction (NMJ), their patterns differ 11. The role of RIα in mediating nicotinic acetylcholine receptor (nAChR) stabilization at the postsynaptic NMJ is known, but the role of RIIα and RIIβ at this site is still not clear 12, 13, 14, 15. In addition, whether PKA RIα plays a role in regulation of NMJ stability in a fibre type‐specific and age‐dependent manner is unknown.…”

Section: Introductionmentioning

confidence: 99%

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Cardiac troponin T and fast skeletal muscle denervation in ageing

Feng

Dong

et al. 2017

J cachexia sarcopenia muscle

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BackgroundAgeing skeletal muscle undergoes chronic denervation, and the neuromuscular junction (NMJ), the key structure that connects motor neuron nerves with muscle cells, shows increased defects with ageing. Previous studies in various species have shown that with ageing, type II fast‐twitch skeletal muscle fibres show more atrophy and NMJ deterioration than type I slow‐twitch fibres. However, how this process is regulated is largely unknown. A better understanding of the mechanisms regulating skeletal muscle fibre‐type specific denervation at the NMJ could be critical to identifying novel treatments for sarcopenia. Cardiac troponin T (cTnT), the heart muscle‐specific isoform of TnT, is a key component of the mechanisms of muscle contraction. It is expressed in skeletal muscle during early development, after acute sciatic nerve denervation, in various neuromuscular diseases and possibly in ageing muscle. Yet the subcellular localization and function of cTnT in skeletal muscle is largely unknown.MethodsStudies were carried out on isolated skeletal muscles from mice, vervet monkeys, and humans. Immunoblotting, immunoprecipitation, and mass spectrometry were used to analyse protein expression, real‐time reverse transcription polymerase chain reaction was used to measure gene expression, immunofluorescence staining was performed for subcellular distribution assay of proteins, and electromyographic recording was used to analyse neurotransmission at the NMJ.ResultsLevels of cTnT expression in skeletal muscle increased with ageing in mice. In addition, cTnT was highly enriched at the NMJ region—but mainly in the fast‐twitch, not the slow‐twitch, muscle of old mice. We further found that the protein kinase A (PKA) RIα subunit was largely removed from, while PKA RIIα and RIIβ are enriched at, the NMJ—again, preferentially in fast‐twitch but not slow‐twitch muscle in old mice. Knocking down cTnT in fast skeletal muscle of old mice: (i) increased PKA RIα and reduced PKA RIIα at the NMJ; (ii) decreased the levels of gene expression of muscle denervation markers; and (iii) enhanced neurotransmission efficiency at NMJ.ConclusionsCardiac troponin T at the NMJ region contributes to NMJ functional decline with ageing mainly in the fast‐twitch skeletal muscle through interfering with PKA signalling. This knowledge could inform useful targets for prevention and therapy of age‐related decline in muscle function.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cardiac troponin T and fast skeletal muscle denervation in ageing

Feng

Dong

et al. 2017

J cachexia sarcopenia muscle

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“…Post‐cDNA solution injection, electrodes connected to an electric pulse generator were placed under and above the T.A muscle and the muscles were subjected to five electric shocks, each of 20 V intensity, 20 ms duration, and 200 ms apart (Dona et al ., 2003). Next the surgical opening of skin was sutured and 10 days post‐transfection, for in vivo microscopy anesthesia and preparation of mice were performed as described (Choi et al ., 2012). …”

Section: Methodsmentioning

confidence: 99%

A compact unc45b‐promoter drives muscle‐specific expression in zebrafish and mouse

Rudeck

Etard

Khan

et al. 2016

Genesis

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Summary: Gene therapeutic approaches to cure genetic diseases require tools to express the rescuing gene exclusively within the affected tissues. Viruses are often chosen as gene transfer vehicles but they have limited capacity for genetic information to be carried and transduced. In addition, to avoid off‐target effects the therapeutic gene should be driven by a tissue‐specific promoter in order to ensure expression in the target organs, tissues, or cell populations. The larger the promoter, the less space will be left for the respective gene. Thus, there is a need for small but tissue‐specific promoters. Here, we describe a compact unc45b promoter fragment of 195 bp that retains the ability to drive gene expression exclusively in skeletal and cardiac muscle in zebrafish and mouse. Remarkably, the described unc45b promoter fragment not only drives muscle‐specific expression but presents heat‐shock inducibility, allowing a temporal and spatial quantity control of (trans)gene expression. Here, we demonstrate that the transgenic expression of the smyd1b gene driven by the unc45b promoter fragment is able to rescue the embryonically lethal heart and skeletal muscle defects in smyd1b‐deficient flatline mutant zebrafish. Our findings demonstrate that the described muscle‐specific unc45b promoter fragment might be a valuable tool for the development of genetic therapies in patients suffering from myopathies. genesis 54:431–438, 2016. © 2016 The Authors. Genesis Published by Wiley Periodicals, Inc.

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Inherited disorders of the neuromuscular junction: an update

2014

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Congenital myasthenic syndromes (CMSs) are a group of heterogeneous inherited disorders caused by mutations in genes affecting the function and structure of the neuromuscular junction. This review updates the reader on established and novel subtypes of congenital myasthenia, and the treatment strategies for these increasingly heterogeneous disorders. The discovery of mutations associated with the N-glycosylation pathway and in the family of serine peptidases has shown that causative genes encoding ubiquitously expressed molecules can produce defects at the human neuromuscular junction. By contrast, mutations in lipoprotein-like receptor 4 (LRP4), a long-time candidate gene for congenital myasthenia, and a novel phenotype of myasthenia with distal weakness and atrophy due to mutations in AGRN have now been described. In addition, a pathogenic splicing mutation in a nonfunctional exon of CHRNA1 has been reported emphasizing the importance of analysing nonfunctional exons in genetic analysis. The benefit of salbutamol and ephedrine alone or combined with pyridostigmine or 3,4-DAP is increasingly being reported for particular subtypes of CMS.

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Rapsyn mediates subsynaptic anchoring of PKA type I and stabilisation of acetylcholine receptor in vivo

Cited by 41 publications

References 44 publications

Cardiac troponin T and fast skeletal muscle denervation in ageing

Cardiac troponin T and fast skeletal muscle denervation in ageing

A compact unc45b‐promoter drives muscle‐specific expression in zebrafish and mouse

Inherited disorders of the neuromuscular junction: an update

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