Altered synaptic synchrony in motor nerve terminals lacking P/Q‐calcium channels

Depetris, Rafael S.; Nudler, Silvana I.; Uchitel, Osvaldo D.; Urbano, Francisco J.

doi:10.1002/syn.20516

Cited by 21 publications

(15 citation statements)

References 23 publications

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“…This close spatial locality may well be the reason P/Q-type VGCCs play a more prominent role in the mature NMJ where efficient bulk release of transmitter is required. Mice lacking P/Q-type VGCCs display decreased quantal content and synchrony of transmitter release, again highlighting the importance of P/Q-type channels in efficient transmitter release (Urbano 18 et al, 2003;Depetris et al, 2008). It was shown that N-type VGCCs were the primary mediators of transmitter release with R-type VGCCs also playing a role.…”

Section: Voltage Gated Calcium Channelsmentioning

confidence: 99%

“…The use of VGCC specific toxins as a tool to evaluate the contribution of VGCC subtypes in mediating transmitter release is well established (Kasai et al, 1987;Llinas et al, 1989;Hillyard et al, 1992;Iwasaki et al, 2000;Santafe et al, 2001;Pardo et al, 2006;Depetris et al, 2008). Here, the toxins ω-CTX GVIA and ω-AGA IVA were used to elucidate the VGCC subtypes present and involved in mediation of transmitter release at both, wild-type and lamb2 -/-NMJs during development.…”

Section: Toxin Preparation and Applicationmentioning

confidence: 99%

“…Toxins were prepared as stock solutions dissolved in distilled water with ω-CTX GVIA as 0.5 mM stocks and ω-AGA IVA as 100 μM stocks, and stored at -20 Regehr & Mintz, 1994). The concentration of these toxins varies considerably in literature (ω-CTX GVIA; 1-5 μM, ω-AGA IVA; 30-200 ηM), primarily due to preparations investigated ranging from neuronal cells, and neonatal to adult rodent skeletal muscle (Protti & Uchitel, 1993;Plomp et al, 2003;Depetris et al, 2008). This study required a suitable concentration to be selected given the age groups investigated and the focus on observing the developmental switch from N-to P/Q-type VGCC mediation in transmitter release.…”

Section: Toxin Preparation and Applicationmentioning

confidence: 99%

“…This study required a suitable concentration to be selected given the age groups investigated and the focus on observing the developmental switch from N-to P/Q-type VGCC mediation in transmitter release. The toxin concentrations selected for use in this protocol were 50 ηM ω-Aga IVA and 100 ηM ω-CgTx GVIA, similar to prior studies investigating VGCC mediation of NMJ transmission Depetris et al, 2008).…”

Section: Toxin Preparation and Applicationmentioning

confidence: 99%

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The functional role of laminins-α4 and -β2 in development of the neuromuscular junction

Chand¹

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The precise development and organisation of the neuromuscular junction (NMJ) is critical for the production of efficient neurotransmission signals. Disruption of these specialisations may result in severely altered transmission properties at the NMJ.Signalling and adhesion molecules have long been established to be key mediators in the distribution of synaptic specialisations. The basal lamina acts to maintain stability of the associated tissue and contains a number of these signalling and adhesion molecules. The laminins, a family of large multimeric proteins, are one of the key components of the basal lamina that act as specific cell regulators and provide mechanical stability. Laminins have been shown to form an interconnecting network that assists in stabilisation of the basal lamina and provides attachment sites for other basal lamina components. The synapse specific laminin chains, -α4, -α5, and -β2, play an essential role in differentiation and organisation of the NMJ. These chains form the laminin isoforms, laminin-221 (α2β2γ1), laminin-421 (α4β2γ1), and laminin-521 (α5β2γ1).Laminin-β2, found in each of the three synapse specific isoforms, has been shown to organise presynaptic specialisations at the developing NMJ. In vitro laminin-β2 is able to interact directly with N-type and P/Q-type voltage-gated calcium This study examined the role of laminin-β2 in the organisation of N-and P/Q-type VGCCs at active zones of developing postnatal day 8 (P8) and matured, postnatal day 18 (P18) NMJs.The contribution of each channel to the release of transmitter was assessed using intracellular electrode recordings of end-plate potentials (EPPs). The VGCC toxins, ω-conotoxin-GVIA and ω-agatoxin-IVA, were used to specifically target N-and P/Q-type NMJs displayed significantly higher levels of synaptic depression under high frequency stimuli and altered paired pulse facilitation compared to wild-type littermates. Analysis of the binomial parameters of neurotransmitter release demonstrated a decrease in quantal release as a result of a decrease in the number of active release sites, but not in the average probability of transmitter release from these sites. Our functional findings suggest alterations in the short-term plasticity of the NMJ and possibly defective recycling of ii synaptic vesicles and/or the calcium handling at lama4 -/-NMJs. We propose that alterations to synapsin I and its associated molecules may be partly responsible for the changes in neurotransmission observed at lama4 -/-NMJs. Our findings demonstrate altered distribution and expression of presynaptic components associated with active zones, specifically an increase in the number of synaptic vesicles and a decrease in the density of the fluorescently labelled Bassoon at the active zone region. Our results suggest that the fewer active release sites may compensate for the deficits of the lama4 -/-NMJs by alterations to pre-and postsynaptic specialisations.In conclusion, this thesis has identified that laminins-α4 and -β2 play fundamental role...

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Section: Voltage Gated Calcium Channelsmentioning

confidence: 99%

Section: Toxin Preparation and Applicationmentioning

confidence: 99%

Section: Toxin Preparation and Applicationmentioning

confidence: 99%

Section: Toxin Preparation and Applicationmentioning

confidence: 99%

See 2 more Smart Citations

The functional role of laminins-α4 and -β2 in development of the neuromuscular junction

Chand¹

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“…Disruption of these components may result in altered efficiency of neurotransmission at the synapse (Li et al, 1995;Knight et al, 2003;Urbano et al, 2003;Depetris et al, 2008;Chand et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

The role of synaptic laminins-α4 and -β2 in maturation and maintenance of the neuromuscular synapse

Lee¹

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The proper development, maturation and maintenance of the neuromuscular junction (NMJ) are critical for ensuring efficient neurotransmission. Proteins found within the basal lamina of the synaptic cleft, namely the laminins family, are heavily involved in maintaining normal structure and function of the NMJ. In particular, individual laminin chains such as laminin-β2, -α4 and -α5 play essential roles in organisation and maintenance of the NMJ. These laminin chains interact together to form three synapse specific laminin heterotrimers; laminin-221 (α2β2γ1), laminin-421 (α4β2γ1) and laminin-521 (α5β2γ1).Laminin-β2 is the common laminin chain found in each of these synapse specific laminin heterotrimers. In-vitro it has been shown to play a key role in the organisation of the presynaptic elements at the NMJ via its interaction and clustering of the N-and P/Q-type voltage-gated calciums (VGCCs). During development of the NMJ, both N-and P/Q-type VGCCs are involved in mediating neurotransmitter release. As the NMJ matures, P/Q-type becomes the dominant channel involved in release while N-type takes on the role of fine-tuning calcium influx. Laminin-α4, on the other hand, ensures proper alignment of presynaptic active zones to postjunctional folds at the NMJ, with its loss resulting in misalignment of these specialisations. Furthermore, this laminin chain has been shown to be involved in the maintenance of the NMJ with the observation of premature ageing features at 6 months of age (6MO) in laminin-α4 deficient mice (lama4 NMJs.In conclusion, this thesis has identified the significant roles laminins-α4 and -β2 play at the NMJ during development, maturation and maintenance. Results suggest that laminin-β2 is not only an important regulator of the presynaptic maturation through the switching of VGCCs and clustering of P/Q-type VGCCs, but also equally important for maturation of the postsynaptic apparatus. Ipropose that laminin-β2 is important for the maturation of each component at the NMJ. The altered responses in transmission properties presented by aged wild-type NMJs which resembled adult lama4 -/-, preceded by altered expression of laminin-α4 chain, strongly suggest that laminin-α4 is not only important for maintaining proper alignment of pre-to postsynaptic NMJ, but also essentially important for maintaining a healthy adult NMJ. Finally, I observed early alterations in expression of laminin-α4 at the NMJs in diseased mouse model of ALS prior to any appearance of neuromotor impairment, suggesting a potential involvement of laminins in NMJ degeneration associated with neuromuscular disorders such as ALS.ii

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CaV2.1 (P/Q) Voltage Activated Ca2+ Channels and Synaptic Transmission in Genetic and Autoimmune Diseases

Uchitel

2013

Modulation of Presynaptic Calcium Channels

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Altered synaptic synchrony in motor nerve terminals lacking P/Q‐calcium channels

Cited by 21 publications

References 23 publications

The functional role of laminins-α4 and -β2 in development of the neuromuscular junction

The functional role of laminins-α4 and -β2 in development of the neuromuscular junction

The role of synaptic laminins-α4 and -β2 in maturation and maintenance of the neuromuscular synapse

CaV2.1 (P/Q) Voltage Activated Ca2+ Channels and Synaptic Transmission in Genetic and Autoimmune Diseases

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