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Sunday Driver links axonal transport to damage signaling.

Cavalli V, Kujala P, Klumperman J, Goldstein LS - J. Cell Biol. (2005)

Bottom Line: We found that syd and JNK3 are present on vesicular structures in axons, are transported in both the anterograde and retrograde axonal transport pathways, and interact with kinesin-I and the dynactin complex.Finally, we found that injury induces an enhanced interaction between syd and dynactin.Thus, a mobile axonal JNK-syd complex may generate a transport-dependent axonal damage surveillance system.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA.

ABSTRACT
Neurons transmit long-range biochemical signals between cell bodies and distant axonal sites or termini. To test the hypothesis that signaling molecules are hitchhikers on axonal vesicles, we focused on the c-Jun NH2-terminal kinase (JNK) scaffolding protein Sunday Driver (syd), which has been proposed to link the molecular motor protein kinesin-1 to axonal vesicles. We found that syd and JNK3 are present on vesicular structures in axons, are transported in both the anterograde and retrograde axonal transport pathways, and interact with kinesin-I and the dynactin complex. Nerve injury induces local activation of JNK, primarily within axons, and activated JNK and syd are then transported primarily retrogradely. In axons, syd and activated JNK colocalize with p150Glued, a subunit of the dynactin complex, and with dynein. Finally, we found that injury induces an enhanced interaction between syd and dynactin. Thus, a mobile axonal JNK-syd complex may generate a transport-dependent axonal damage surveillance system.

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P-JNK and syd are transported mainly retrogradely after nerve injury. (A) Sciatic nerve double ligation was performed with 2 knots 8 mm apart for 6 h (B, scheme). The nerve was dissected, divided into two equal parts representing the retrograde (Retro) and anterograde (Antero) pool, and analyzed by SDS-PAGE. Replicates are shown in the online supplemental material. (B) Quantification of the fraction of retrograde (R, black bars) and anterograde (A, gray bars) over total (A + R) (± SEM; n = 5). (C) Values were normalized to the level of tubulin as in A, but the retrograde and anterograde pools were analyzed by immunofluorescence. The ligation site is indicated with white arrows. Bar, 100 μm.
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fig6: P-JNK and syd are transported mainly retrogradely after nerve injury. (A) Sciatic nerve double ligation was performed with 2 knots 8 mm apart for 6 h (B, scheme). The nerve was dissected, divided into two equal parts representing the retrograde (Retro) and anterograde (Antero) pool, and analyzed by SDS-PAGE. Replicates are shown in the online supplemental material. (B) Quantification of the fraction of retrograde (R, black bars) and anterograde (A, gray bars) over total (A + R) (± SEM; n = 5). (C) Values were normalized to the level of tubulin as in A, but the retrograde and anterograde pools were analyzed by immunofluorescence. The ligation site is indicated with white arrows. Bar, 100 μm.

Mentions: Typical single sciatic nerve ligation experiments indicated that syd and JNK3 are transported predominantly in the anterograde direction (Fig. 3) and that the injury caused by the ligation leads to local axonal JNK activation. Previous workers (Kenney and Kocsis, 1998) reported the appearance of P-JNK in neuronal cell bodies in a time- and distance-dependent manner from the injury site, suggesting the existence of a microtubule-dependent signaling system. To test if P-JNK itself is a positive injury signal and travels retrogradely toward the cell body after injury, we performed a double ligation experiment (i.e., two ligatures were placed 8 mm apart). This design allowed us to examine transport in an injured nerve segment without contributions of new material transported from the cell body or from the nerve terminal. In this design, the proximal ligation represents a collecting site for molecules traveling from the distal ligation. After 6 h, the nerve was dissected and divided into two equal parts representing retrograde (Fig. 6 B, R) and anterograde (Fig. 6 B, A) fractions (Fig. 6 B, scheme). P-JNK, JNK3, and syd were enriched in the retrograde pool, whereas APP was enriched in the anterograde pool (Fig. 6, A and B). A similar observation was made when the portions corresponding to the retrograde and anterograde pool close to the ligation sites were examined by immunofluorescence (Fig. 6 C). These results suggest that upon encountering an injury, anterograde syd and P-JNK switch to the retrograde pathway, whereas APP transport is not affected and remains mainly anterograde.


Sunday Driver links axonal transport to damage signaling.

Cavalli V, Kujala P, Klumperman J, Goldstein LS - J. Cell Biol. (2005)

P-JNK and syd are transported mainly retrogradely after nerve injury. (A) Sciatic nerve double ligation was performed with 2 knots 8 mm apart for 6 h (B, scheme). The nerve was dissected, divided into two equal parts representing the retrograde (Retro) and anterograde (Antero) pool, and analyzed by SDS-PAGE. Replicates are shown in the online supplemental material. (B) Quantification of the fraction of retrograde (R, black bars) and anterograde (A, gray bars) over total (A + R) (± SEM; n = 5). (C) Values were normalized to the level of tubulin as in A, but the retrograde and anterograde pools were analyzed by immunofluorescence. The ligation site is indicated with white arrows. Bar, 100 μm.
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Related In: Results  -  Collection

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fig6: P-JNK and syd are transported mainly retrogradely after nerve injury. (A) Sciatic nerve double ligation was performed with 2 knots 8 mm apart for 6 h (B, scheme). The nerve was dissected, divided into two equal parts representing the retrograde (Retro) and anterograde (Antero) pool, and analyzed by SDS-PAGE. Replicates are shown in the online supplemental material. (B) Quantification of the fraction of retrograde (R, black bars) and anterograde (A, gray bars) over total (A + R) (± SEM; n = 5). (C) Values were normalized to the level of tubulin as in A, but the retrograde and anterograde pools were analyzed by immunofluorescence. The ligation site is indicated with white arrows. Bar, 100 μm.
Mentions: Typical single sciatic nerve ligation experiments indicated that syd and JNK3 are transported predominantly in the anterograde direction (Fig. 3) and that the injury caused by the ligation leads to local axonal JNK activation. Previous workers (Kenney and Kocsis, 1998) reported the appearance of P-JNK in neuronal cell bodies in a time- and distance-dependent manner from the injury site, suggesting the existence of a microtubule-dependent signaling system. To test if P-JNK itself is a positive injury signal and travels retrogradely toward the cell body after injury, we performed a double ligation experiment (i.e., two ligatures were placed 8 mm apart). This design allowed us to examine transport in an injured nerve segment without contributions of new material transported from the cell body or from the nerve terminal. In this design, the proximal ligation represents a collecting site for molecules traveling from the distal ligation. After 6 h, the nerve was dissected and divided into two equal parts representing retrograde (Fig. 6 B, R) and anterograde (Fig. 6 B, A) fractions (Fig. 6 B, scheme). P-JNK, JNK3, and syd were enriched in the retrograde pool, whereas APP was enriched in the anterograde pool (Fig. 6, A and B). A similar observation was made when the portions corresponding to the retrograde and anterograde pool close to the ligation sites were examined by immunofluorescence (Fig. 6 C). These results suggest that upon encountering an injury, anterograde syd and P-JNK switch to the retrograde pathway, whereas APP transport is not affected and remains mainly anterograde.

Bottom Line: We found that syd and JNK3 are present on vesicular structures in axons, are transported in both the anterograde and retrograde axonal transport pathways, and interact with kinesin-I and the dynactin complex.Finally, we found that injury induces an enhanced interaction between syd and dynactin.Thus, a mobile axonal JNK-syd complex may generate a transport-dependent axonal damage surveillance system.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA.

ABSTRACT
Neurons transmit long-range biochemical signals between cell bodies and distant axonal sites or termini. To test the hypothesis that signaling molecules are hitchhikers on axonal vesicles, we focused on the c-Jun NH2-terminal kinase (JNK) scaffolding protein Sunday Driver (syd), which has been proposed to link the molecular motor protein kinesin-1 to axonal vesicles. We found that syd and JNK3 are present on vesicular structures in axons, are transported in both the anterograde and retrograde axonal transport pathways, and interact with kinesin-I and the dynactin complex. Nerve injury induces local activation of JNK, primarily within axons, and activated JNK and syd are then transported primarily retrogradely. In axons, syd and activated JNK colocalize with p150Glued, a subunit of the dynactin complex, and with dynein. Finally, we found that injury induces an enhanced interaction between syd and dynactin. Thus, a mobile axonal JNK-syd complex may generate a transport-dependent axonal damage surveillance system.

Show MeSH
Related in: MedlinePlus