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UNC-33 (CRMP) and ankyrin organize microtubules and localize kinesin to polarize axon-dendrite sorting.

Maniar TA, Kaplan M, Wang GJ, Shen K, Wei L, Shaw JE, Koushika SP, Bargmann CI - Nat. Neurosci. (2011)

Bottom Line: The causative relationships among these molecules are unknown.We show here that Caenorhabditis elegans CRMP (UNC-33) acts early in neuronal development, together with ankyrin (UNC-44), to organize microtubule asymmetry and axon-dendrite sorting.We suggest that UNC-44 and UNC-33 direct polarized sorting through their global effects on neuronal microtubule organization.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neural Circuits and Behavior, Howard Hughes Medical Institute, The Rockefeller University, New York, New York, USA.

ABSTRACT
The polarized distribution of neuronal proteins to axons and dendrites relies on microtubule-binding proteins such as CRMP, directed motors such as the kinesin UNC-104 (Kif1A) and diffusion barriers such as ankyrin. The causative relationships among these molecules are unknown. We show here that Caenorhabditis elegans CRMP (UNC-33) acts early in neuronal development, together with ankyrin (UNC-44), to organize microtubule asymmetry and axon-dendrite sorting. In unc-33 and unc-44 mutants, axonal proteins were mislocalized to dendrites and vice versa, suggesting bidirectional failures of axon-dendrite identity. unc-44 directed UNC-33 localization to axons, where it was enriched in a region that resembled the axon initial segment. unc-33 and unc-44 were both required to establish the asymmetric dynamics of axonal and dendritic microtubules; in their absence, microtubules were disorganized, the axonal kinesin UNC-104 invaded dendrites, and inappropriate UNC-104 activity randomized axonal protein sorting. We suggest that UNC-44 and UNC-33 direct polarized sorting through their global effects on neuronal microtubule organization.

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unc-104/KIF1A kinesin mislocalizes presynaptic proteins to dendrites in unc-33 mutants(a-p) Representative images of RAB-3::mCherry and SAD-1::GFP in PVD neurons of wild type (a-d), unc-104(e1265) (e-h), unc-33(ky880) (i-l), and unc-104 unc-33 (m-p) animals, with corresponding diagrams. For each set of fluorescence micrographs, the top panel is the maximum intensity projection of dendritic focal planes and the bottom panel is the maximum intensity projection of axonal focal planes. White and yellow arrowheads indicate axonal and dendritic puncta, respectively; ‘cb’ marks the PVD cell body, and asterisks mark gut autofluorescence. Anterior is at left and dorsal is up in all panels. Scale bar, 10 μm.(q,r) Quantification of axonal localization defects (q) and dendritic mislocalization defects (r) of RAB-3::mCherry and SAD-1::GFP, as in Fig. 1; n>30 animals/genotype. Error bars indicate s.e.p.
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Figure 4: unc-104/KIF1A kinesin mislocalizes presynaptic proteins to dendrites in unc-33 mutants(a-p) Representative images of RAB-3::mCherry and SAD-1::GFP in PVD neurons of wild type (a-d), unc-104(e1265) (e-h), unc-33(ky880) (i-l), and unc-104 unc-33 (m-p) animals, with corresponding diagrams. For each set of fluorescence micrographs, the top panel is the maximum intensity projection of dendritic focal planes and the bottom panel is the maximum intensity projection of axonal focal planes. White and yellow arrowheads indicate axonal and dendritic puncta, respectively; ‘cb’ marks the PVD cell body, and asterisks mark gut autofluorescence. Anterior is at left and dorsal is up in all panels. Scale bar, 10 μm.(q,r) Quantification of axonal localization defects (q) and dendritic mislocalization defects (r) of RAB-3::mCherry and SAD-1::GFP, as in Fig. 1; n>30 animals/genotype. Error bars indicate s.e.p.

Mentions: The appearance of axonal proteins in dendrites in unc-33 mutants could result either from a passive redistribution of proteins through diffusion, or from active defects in polarized protein traffic. To distinguish between these mechanisms, we combined unc-33 mutations with mutations in unc-104/KIF1A, a conserved Kinesin-3 family member that mediates the axonal transport of presynaptic vesicles and other presynaptic proteins 33, 34. In unc-104 mutants, axonal proteins are trapped in the cell body, but dendritic proteins are localized normally 10, 35. As expected, RAB-3::mCherry and SAD-1::GFP markers were restricted to the PVD cell bodies in unc-104 mutants (Fig. 4a-h), a pattern distinct from the randomized distribution in unc-33 (Fig. 4i-l). An unc-33 unc-104 double mutant resembled unc-104, with RAB-3::mCherry and SAD-1::GFP restriction to the PVD cell body (Fig. 4m-r). Therefore, both the appropriate axonal localization and the inappropriate dendrite localization of synaptic proteins in unc-33 mutants require UNC-104, suggesting that the axonal UNC-104 kinesin gains access to dendrites in unc-33 mutants.


UNC-33 (CRMP) and ankyrin organize microtubules and localize kinesin to polarize axon-dendrite sorting.

Maniar TA, Kaplan M, Wang GJ, Shen K, Wei L, Shaw JE, Koushika SP, Bargmann CI - Nat. Neurosci. (2011)

unc-104/KIF1A kinesin mislocalizes presynaptic proteins to dendrites in unc-33 mutants(a-p) Representative images of RAB-3::mCherry and SAD-1::GFP in PVD neurons of wild type (a-d), unc-104(e1265) (e-h), unc-33(ky880) (i-l), and unc-104 unc-33 (m-p) animals, with corresponding diagrams. For each set of fluorescence micrographs, the top panel is the maximum intensity projection of dendritic focal planes and the bottom panel is the maximum intensity projection of axonal focal planes. White and yellow arrowheads indicate axonal and dendritic puncta, respectively; ‘cb’ marks the PVD cell body, and asterisks mark gut autofluorescence. Anterior is at left and dorsal is up in all panels. Scale bar, 10 μm.(q,r) Quantification of axonal localization defects (q) and dendritic mislocalization defects (r) of RAB-3::mCherry and SAD-1::GFP, as in Fig. 1; n>30 animals/genotype. Error bars indicate s.e.p.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4328884&req=5

Figure 4: unc-104/KIF1A kinesin mislocalizes presynaptic proteins to dendrites in unc-33 mutants(a-p) Representative images of RAB-3::mCherry and SAD-1::GFP in PVD neurons of wild type (a-d), unc-104(e1265) (e-h), unc-33(ky880) (i-l), and unc-104 unc-33 (m-p) animals, with corresponding diagrams. For each set of fluorescence micrographs, the top panel is the maximum intensity projection of dendritic focal planes and the bottom panel is the maximum intensity projection of axonal focal planes. White and yellow arrowheads indicate axonal and dendritic puncta, respectively; ‘cb’ marks the PVD cell body, and asterisks mark gut autofluorescence. Anterior is at left and dorsal is up in all panels. Scale bar, 10 μm.(q,r) Quantification of axonal localization defects (q) and dendritic mislocalization defects (r) of RAB-3::mCherry and SAD-1::GFP, as in Fig. 1; n>30 animals/genotype. Error bars indicate s.e.p.
Mentions: The appearance of axonal proteins in dendrites in unc-33 mutants could result either from a passive redistribution of proteins through diffusion, or from active defects in polarized protein traffic. To distinguish between these mechanisms, we combined unc-33 mutations with mutations in unc-104/KIF1A, a conserved Kinesin-3 family member that mediates the axonal transport of presynaptic vesicles and other presynaptic proteins 33, 34. In unc-104 mutants, axonal proteins are trapped in the cell body, but dendritic proteins are localized normally 10, 35. As expected, RAB-3::mCherry and SAD-1::GFP markers were restricted to the PVD cell bodies in unc-104 mutants (Fig. 4a-h), a pattern distinct from the randomized distribution in unc-33 (Fig. 4i-l). An unc-33 unc-104 double mutant resembled unc-104, with RAB-3::mCherry and SAD-1::GFP restriction to the PVD cell body (Fig. 4m-r). Therefore, both the appropriate axonal localization and the inappropriate dendrite localization of synaptic proteins in unc-33 mutants require UNC-104, suggesting that the axonal UNC-104 kinesin gains access to dendrites in unc-33 mutants.

Bottom Line: The causative relationships among these molecules are unknown.We show here that Caenorhabditis elegans CRMP (UNC-33) acts early in neuronal development, together with ankyrin (UNC-44), to organize microtubule asymmetry and axon-dendrite sorting.We suggest that UNC-44 and UNC-33 direct polarized sorting through their global effects on neuronal microtubule organization.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neural Circuits and Behavior, Howard Hughes Medical Institute, The Rockefeller University, New York, New York, USA.

ABSTRACT
The polarized distribution of neuronal proteins to axons and dendrites relies on microtubule-binding proteins such as CRMP, directed motors such as the kinesin UNC-104 (Kif1A) and diffusion barriers such as ankyrin. The causative relationships among these molecules are unknown. We show here that Caenorhabditis elegans CRMP (UNC-33) acts early in neuronal development, together with ankyrin (UNC-44), to organize microtubule asymmetry and axon-dendrite sorting. In unc-33 and unc-44 mutants, axonal proteins were mislocalized to dendrites and vice versa, suggesting bidirectional failures of axon-dendrite identity. unc-44 directed UNC-33 localization to axons, where it was enriched in a region that resembled the axon initial segment. unc-33 and unc-44 were both required to establish the asymmetric dynamics of axonal and dendritic microtubules; in their absence, microtubules were disorganized, the axonal kinesin UNC-104 invaded dendrites, and inappropriate UNC-104 activity randomized axonal protein sorting. We suggest that UNC-44 and UNC-33 direct polarized sorting through their global effects on neuronal microtubule organization.

Show MeSH
Related in: MedlinePlus