Dynamic neuromuscular remodeling precedes motor-unit loss in a mouse model of ALS
- Université de Montréal, Canada
- Centre de recherche du Centre Hospitalier de l'Université de Montréal, Canada
Figures
Figure 1 with 1 supplement
NMJs in a single motor-unit of WT/YFP mice are stable.
(A) Images at different focal planes of the same MU arbor from a WT/YFP mice during four sessions, with a higher magnification on-focus image of one NMJ (digital zoom, dashed box in low …
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Figure 1—source data 1
Spreadsheet for the innervation status of all NMJs in each MU arbor imaged in WT/YFP mice and individual graphical representations.
In the spreadsheet, a value of ‘1’ represents an NMJ fully innervated by the MU while a value of ‘x’ represents an NMJ which could not be fully resolved on that session. The global percentages for each MU are included below each table with individual histograms for each MU. The histograms are also compiled in the PDF file.
- https://doi.org/10.7554/eLife.41973.005
Figure 1—figure supplement 1
Classification of NMJs within single MUs.
Representative examples of the initial and subsequent observation of NMJs classified as completely innervated (inn.) (A) or partially innervated (B) repaired (C) re-innervated (partially or …
Figure 2 with 1 supplement
Single motor-unit degeneration is initially asynchronous and can last for several weeks in SOD1G37R/YFP mice.
(A) Images at two different focal planes of the same MU arbor during four imaging sessions (1, 2, 3 and 5), with on-focus images at higher magnification of some NMJs (digital zoom, dashed boxes in …
Figure 2—figure supplement 1
Mating of floxSOD1G37R to thy1-YFP-H mice did not alter disease course or mutant SOD1 levels.
(A) Mating scheme for SOD1G37R/YFP and WT/YFP mice. (B) Body weight curve of SOD1G37R and SOD1G37R/YFP mice (black and red, respectively), showing a similar weight between both groups (repeated …
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Figure 2—figure supplement 1—source data 1
Raw values of body weight, grip strength, α- and γ-motor neuron counts, percentages of YFP-expression motor neurons and NMJ innervation as depicted in Figure 2—figure supplement 1B,C,E,F,H and I, respectively.
Values in the motor neuron counts table represent the average number of motor neurons per ventral horn counted from 15 to 20 lumbar spinal cord sections. Values in the NMJ innervation table represent the number of completely denervated, partially denervated and fully innervated NMJs, as well as the number of denervated NMJs (partial + complete) and the total number of NMJs (complete + partial + innervated).
- https://doi.org/10.7554/eLife.41973.008
Figure 3 with 1 supplement
Asynchronous branch-specific dismantlement precedes synchronous motor-unit degeneration in SOD1G37R/YFP mice.
(A) Example of another MU arbor showing two partially innervated NMJs (arrowheads) on session 1 and 2, before the whole motor axon degenerated on session 6. Note the presence of YFP fragments along …
Figure 3—figure supplement 1
Motor-units are mainly fast-fatigable on the surface of the Tibialis anterior in SOD1G37R/YFP mice.
Fiber type composition of TA muscles from WT/YFP (A) and SOD1G37R/YFP (B) after repeated in vivo imaging (symptomatic stage, contralateral TA). Muscle cross-sections were stained with antibodies …
Figure 4 with 2 supplements
MUs retracted and expanded constantly during disease progression in SOD1G37R/YFP mice.
(A) (B) Images of a MU branch on two sessions (A) with on-focus high-magnification images of 4 NMJs (B) (dashed boxes in A), where one NMJ remained innervated (#1, B’), one was partially lost (#2, …
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Figure 4—source data 1
Spreadsheet for the innervation status of all NMJs in each MU arbor imaged in SOD1/YFP mice and individual graphical representations.
In the spreadsheet values of ‘1’, ‘0.5’ and ‘0’ represent an NMJ which is fully innervated, partially innervated or not innervated by the imaged MU. A value of ‘x’ represents an NMJ which could not be fully resolved on that session. The change relative to last session (delta) and the classification of the NMJ (repair, reinnervated or new) of each NMJ as well as the global percentages for each MU and individual histograms for each MU are presented below the innervation status of each NMJ. The data is split between three tabs: the females, the males and the compilation, which contains the individual data points for the histogram in Figure 4C. The histograms are also compiled in the PDF file.
- https://doi.org/10.7554/eLife.41973.015
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Figure 4—source data 2
Spreadsheet including the number and the percentage of lost and gained NMJs as a function of their branch order.
This data is presented in the histogram in Figure 3D.
- https://doi.org/10.7554/eLife.41973.016
Figure 4—figure supplement 1
Heat-map of all MU changes across all sessions.
The green-red gradient represents the ratio of gains over losses, while the numbers indicate the % of gains/losses on a given session relative to the first session. Note that most MU underwent gains …
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Figure 4—figure supplement 1—source data 1
Percentage of change (gains, losses, total or delta) on each session relative to the first session.
This data was obtained from the data presented in Figure 4—source data 1.
- https://doi.org/10.7554/eLife.41973.014
Figure 4—figure supplement 2
Asynchronously lost postsynaptic sites do not become refractory to other MUs.
(A) and (B) illustrate the same NMJ during in vivo and after IHC respectively. Arrows point to a distinctive landmark of postsynaptic area. (A). Examples of NMJs that were asynchronously lost by the …
Figure 5
Denervation events tended to propagate from the first lost NMJ in the MU, with a higher susceptibility of distal branches.
(A) Example of a full MU arbor tracing used to calculate the distance of every NMJ from the first one lost (T0). Red dots indicate denervation events and their time (in session numbers) from the …
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Figure 5—source data 1
Spreadsheet of the innervation status of all NMJs in each MU arbor with their distance from first lost NMJ in the arbor (in µm) and timing of subsequent losses relative to the initial losses (T0, T1, T2, T3 and T4).
Tables at the bottom of the file represent the compilations across all MUs. This data is represented in Figure 4B.
- https://doi.org/10.7554/eLife.41973.018
Figure 6
Proposed model of NMJ dynamism in ALS.
NMJs within single MUs are lost asynchronously independently of motor axon degeneration (1). Local neuromuscular factors contribute to denervation events, which thus propagate from the first lost …
Tables
Key resources table
| Reagent type (species) or resource | Designation | Source or reference | Identifiers | Additional information |
|---|---|---|---|---|
| Strain, strain background (Mus muculus, C57BL/6J) | loxSOD1G37R | PMID: 16741123; now also available from Jax mice (stock number 016149) | RRID:MGI:3629226 | Originaly imported from Don W. Cleveland's facilities (UCSD). |
| Strain, strain background (M. muculus, C57BL/6J) | Thy1-YFP line H | Jax mice (stock number 003782) | RRID:MGI:3497947 | |
| Antibody | Goat polyclonal anti-choline acetyl-transferase | EMD Millipore (AB144P) | RRID:AB_207951 | (1:100) |
| Antibody | Mouse monoclonal IgG1 anti-NeuN, clone A60 | EMD Millipore (MAB377) | RRID:AB_2298772 | (1:300) |
| Antibody | Rabbit polyclonal anti-S100β | Agilent Dako (Z0311) | RRID:AB_10013383 | (1:250) |
| Antibody | Chicken polyclonal anti-neurofilament M | Rockland Inc. (212-901-D84) | RRID:AB_11182576 | (1:2000) |
| Antibody | Mouse monoclonal IgG1 anti-synaptic vesicular protein 2 | DSHB (SV2) | RRID:AB_2315387 | (1:2000) |
| Antibody | Mouse monoclonal IgG2b anti-MHC1 | DSHB (BA-D5c) | RRID:AB_2235587 | (1:100) |
| Antibody | Mouse monoclonal IgG1 anti-MHC2a | DSHB (SC-71c) | RRID:AB_2147165 | (1:200) |
| Antibody | Mouse monoclonal IgM anti-MHC2b | DSHB (BF-F3c) | RRID:AB_2266724 | (1:200) |
| Antibody | Mouse monoclonal IgM anti-MHC2x | DSHB (6H1s) | RRID:AB_1157897 | (1:10) |
| Antibody | Mouse monoclonal IgG1 anti-MHC all-but-IIx | DSHB (BF-35c) | RRID:AB_2274680 | (1:200) |
| Antibody | Goat polyclonal anti-mouse IgG1 DyLight 405 | Jackson ImmunoResearch (115-475-205) | RRID:AB_2338799 | (1:500) |
| Antibody | Donkey polyclonal anti-goat Alexa 594 | Jackson ImmunoResearch (705-585-147) | RRID:AB_2340433 | (1:500) |
| Antibody | Goat polyclonal anti-mouse IgG1 Alexa 647 | Jackson ImmunoResearch (115-605-205) | RRID:AB_2338916 | (1:500) |
| Antibody | Donkey polyclonal anti-chicken Alexa 647 | Jackson ImmunoResearch (703-605-155) | RRID:AB_2340379 | (1:500) |
| Antibody | Donkey polyclonal anti-rabbit Alexa 405 | Jackson ImmunoResearch (711-475-152) | RRID:AB_2340616 | (1:500) |
| Antibody | Goat polyclonal anti-mouse IgM Alexa 647 | Jackson ImmunoResearch (115-605-020) | RRID:AB_2338905 | (1:500) |
| Antibody | Goat polyclonal anti-mouse IgG2b Alexa 488 | Jackson ImmunoResearch (115-545-207) | RRID:AB_2338856 | (1:500) |
| Antibody | Goat polyclonal anti-mouse IgG1 Alexa 594 | Jackson ImmunoResearch (115-585-205) | RRID:AB_2338885 | (1:500) |
| Chemical compound, drug | Alexa 594-conjuguated α-Bungarotoxin | Thermofisher (B13423) | (1:750) (1.33µg/mL) |
Additional files
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Transparent reporting form
- https://doi.org/10.7554/eLife.41973.021
