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Analysis of retrograde transport in motor neurons reveals common endocytic carriers for tetanus toxin and neurotrophin receptor p75NTR.

Lalli G, Schiavo G - J. Cell Biol. (2002)

Bottom Line: However, the nature and dynamics of the membrane compartments involved in this process are poorly characterized.Importantly, TeNT HC and NGF share the same retrograde transport organelles, which are characterized by the presence of the neurotrophin receptor p75NTR.Our results provide the first direct visualization of retrograde transport in living motor neurons, and reveal a novel retrograde route that could be used both by physiological ligands (i.e., neurotrophins) and TeNT to enter the central nervous system.

View Article: PubMed Central - PubMed

Affiliation: Molecular NeuroPathoBiology Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom.

ABSTRACT
Axonal retrograde transport is essential for neuronal growth and survival. However, the nature and dynamics of the membrane compartments involved in this process are poorly characterized. To shed light on this pathway, we established an experimental system for the visualization and the quantitative study of retrograde transport in living motor neurons based on a fluorescent fragment of tetanus toxin (TeNT HC). Morphological and kinetic analysis of TeNT HC retrograde carriers reveals two major groups of organelles: round vesicles and fast tubular structures. TeNT HC carriers lack markers of the classical endocytic pathway and are not acidified during axonal transport. Importantly, TeNT HC and NGF share the same retrograde transport organelles, which are characterized by the presence of the neurotrophin receptor p75NTR. Our results provide the first direct visualization of retrograde transport in living motor neurons, and reveal a novel retrograde route that could be used both by physiological ligands (i.e., neurotrophins) and TeNT to enter the central nervous system.

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Kinetic analysis of TeNT HC carriers in MNs. (a) Displacement of 15 carriers tracked during a representative experiment. Retrograde movement is conventionally shown as positive. Intervals between time points are 5 s. Note the presence of fast tubules (•) and slower vesicles (□). Half-filled squares refer to other types of carriers. (b) Displacement graphs of the tubules from a, setting the start of tracking as time 0, show an apparently constant movement with similar speed. (c) Displacement graphs of the remaining carriers from a show a slower and more discontinuous movement. (d) Average speeds of TeNT HC retrograde carriers (▵; n = 256 carriers from three independent experiments). Round vesicles (□; n = 76) have an average speed distribution different from tubules (•, n = 93). (e) Percentage of the different types of carriers analyzed in d.
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fig2: Kinetic analysis of TeNT HC carriers in MNs. (a) Displacement of 15 carriers tracked during a representative experiment. Retrograde movement is conventionally shown as positive. Intervals between time points are 5 s. Note the presence of fast tubules (•) and slower vesicles (□). Half-filled squares refer to other types of carriers. (b) Displacement graphs of the tubules from a, setting the start of tracking as time 0, show an apparently constant movement with similar speed. (c) Displacement graphs of the remaining carriers from a show a slower and more discontinuous movement. (d) Average speeds of TeNT HC retrograde carriers (▵; n = 256 carriers from three independent experiments). Round vesicles (□; n = 76) have an average speed distribution different from tubules (•, n = 93). (e) Percentage of the different types of carriers analyzed in d.

Mentions: The kinetics of retrograde transport in living MNs can be analyzed by following the displacement of the TeNT HC–labeled carriers. Different groups of structures undergoing retrograde transport can be distinguished: tubules (Fig. 2 , a and b, •), which showed a fast movement, and bright round vesicles (Fig. 2, a and c, □) with a slower speed and frequent stationary periods. Other types were rare bright oval bodies and faint round carriers (Fig. 2, a and c, ┘), which displayed all types of movement seen for tubules and bright vesicles. Tubules and vesicles represent the majority of TeNT HC–labeled structures (66%) (Fig. 2 e).


Analysis of retrograde transport in motor neurons reveals common endocytic carriers for tetanus toxin and neurotrophin receptor p75NTR.

Lalli G, Schiavo G - J. Cell Biol. (2002)

Kinetic analysis of TeNT HC carriers in MNs. (a) Displacement of 15 carriers tracked during a representative experiment. Retrograde movement is conventionally shown as positive. Intervals between time points are 5 s. Note the presence of fast tubules (•) and slower vesicles (□). Half-filled squares refer to other types of carriers. (b) Displacement graphs of the tubules from a, setting the start of tracking as time 0, show an apparently constant movement with similar speed. (c) Displacement graphs of the remaining carriers from a show a slower and more discontinuous movement. (d) Average speeds of TeNT HC retrograde carriers (▵; n = 256 carriers from three independent experiments). Round vesicles (□; n = 76) have an average speed distribution different from tubules (•, n = 93). (e) Percentage of the different types of carriers analyzed in d.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199221&req=5

fig2: Kinetic analysis of TeNT HC carriers in MNs. (a) Displacement of 15 carriers tracked during a representative experiment. Retrograde movement is conventionally shown as positive. Intervals between time points are 5 s. Note the presence of fast tubules (•) and slower vesicles (□). Half-filled squares refer to other types of carriers. (b) Displacement graphs of the tubules from a, setting the start of tracking as time 0, show an apparently constant movement with similar speed. (c) Displacement graphs of the remaining carriers from a show a slower and more discontinuous movement. (d) Average speeds of TeNT HC retrograde carriers (▵; n = 256 carriers from three independent experiments). Round vesicles (□; n = 76) have an average speed distribution different from tubules (•, n = 93). (e) Percentage of the different types of carriers analyzed in d.
Mentions: The kinetics of retrograde transport in living MNs can be analyzed by following the displacement of the TeNT HC–labeled carriers. Different groups of structures undergoing retrograde transport can be distinguished: tubules (Fig. 2 , a and b, •), which showed a fast movement, and bright round vesicles (Fig. 2, a and c, □) with a slower speed and frequent stationary periods. Other types were rare bright oval bodies and faint round carriers (Fig. 2, a and c, ┘), which displayed all types of movement seen for tubules and bright vesicles. Tubules and vesicles represent the majority of TeNT HC–labeled structures (66%) (Fig. 2 e).

Bottom Line: However, the nature and dynamics of the membrane compartments involved in this process are poorly characterized.Importantly, TeNT HC and NGF share the same retrograde transport organelles, which are characterized by the presence of the neurotrophin receptor p75NTR.Our results provide the first direct visualization of retrograde transport in living motor neurons, and reveal a novel retrograde route that could be used both by physiological ligands (i.e., neurotrophins) and TeNT to enter the central nervous system.

View Article: PubMed Central - PubMed

Affiliation: Molecular NeuroPathoBiology Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom.

ABSTRACT
Axonal retrograde transport is essential for neuronal growth and survival. However, the nature and dynamics of the membrane compartments involved in this process are poorly characterized. To shed light on this pathway, we established an experimental system for the visualization and the quantitative study of retrograde transport in living motor neurons based on a fluorescent fragment of tetanus toxin (TeNT HC). Morphological and kinetic analysis of TeNT HC retrograde carriers reveals two major groups of organelles: round vesicles and fast tubular structures. TeNT HC carriers lack markers of the classical endocytic pathway and are not acidified during axonal transport. Importantly, TeNT HC and NGF share the same retrograde transport organelles, which are characterized by the presence of the neurotrophin receptor p75NTR. Our results provide the first direct visualization of retrograde transport in living motor neurons, and reveal a novel retrograde route that could be used both by physiological ligands (i.e., neurotrophins) and TeNT to enter the central nervous system.

Show MeSH
Related in: MedlinePlus