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The short coiled-coil domain-containing protein UNC-69 cooperates with UNC-76 to regulate axonal outgrowth and normal presynaptic organization in Caenorhabditis elegans.

Su CW, Tharin S, Jin Y, Wightman B, Spector M, Meili D, Tsung N, Rhiner C, Bourikas D, Stoeckli E, Garriga G, Horvitz HR, Hengartner MO - J. Biol. (2006)

Bottom Line: UNC-69 and UNC-76 colocalize as puncta in neuronal processes and cooperate to regulate axon extension and synapse formation.We have identified a novel protein complex, composed of UNC-69 and UNC-76, which promotes axonal growth and normal presynaptic organization in C. elegans.As both proteins are conserved through evolution, we suggest that the mammalian homologs of UNC-69 and UNC-76 (SCOCO and FEZ, respectively) may function similarly.

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Affiliation: Institute for Molecular Biology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. chengwensu@gmail.com

ABSTRACT

Background: The nematode Caenorhabditis elegans has been used extensively to identify the genetic requirements for proper nervous system development and function. Key to this process is the direction of vesicles to the growing axons and dendrites, which is required for growth-cone extension and synapse formation in the developing neurons. The contribution and mechanism of membrane traffic in neuronal development are not fully understood, however.

Results: We show that the C. elegans gene unc-69 is required for axon outgrowth, guidance, fasciculation and normal presynaptic organization. We identify UNC-69 as an evolutionarily conserved 108-amino-acid protein with a short coiled-coil domain. UNC-69 interacts physically with UNC-76, mutations in which produce similar defects to loss of unc-69 function. In addition, a weak reduction-of-function allele, unc-69(ju69), preferentially causes mislocalization of the synaptic vesicle marker synaptobrevin. UNC-69 and UNC-76 colocalize as puncta in neuronal processes and cooperate to regulate axon extension and synapse formation. The chicken UNC-69 homolog is highly expressed in the developing central nervous system, and its inactivation by RNA interference leads to axon guidance defects.

Conclusion: We have identified a novel protein complex, composed of UNC-69 and UNC-76, which promotes axonal growth and normal presynaptic organization in C. elegans. As both proteins are conserved through evolution, we suggest that the mammalian homologs of UNC-69 and UNC-76 (SCOCO and FEZ, respectively) may function similarly.

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The unc-69 locus encodes a 108-amino-acid protein with a short coiled-coil domain. (a) Genetic and physical maps of chromosome III in the vicinity of the unc-69 locus. unc-69 is close to and left of ced-9. Cosmids and subclones able to rescue the locomotion defect of unc-69(e587) mutants are shown in bold. B: BamHI; H: HindIII; M: MluI; P: PstI; R: EcoRI; S: SacI. Introduction of a frameshift mutation at the BamHI site in the second exon (denoted with an x) abrogated rescue by the minimal PstI-SacI rescuing fragment. Both splice variants, T07A5.6a and T07A5.6b, are contained within this fragment. (b) The UNC-69 protein sequence. The boxed region is predicted to form a coiled-coil domain. Arrows indicate the positions of the three known unc-69 mutations. Additional amino acids encoded by T07A5.6b are shown in italics (see Additional data file 1). (c) Northern-blot analysis of unc-69 revealed a single major transcript of 0.65 kb (arrow).
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Figure 1: The unc-69 locus encodes a 108-amino-acid protein with a short coiled-coil domain. (a) Genetic and physical maps of chromosome III in the vicinity of the unc-69 locus. unc-69 is close to and left of ced-9. Cosmids and subclones able to rescue the locomotion defect of unc-69(e587) mutants are shown in bold. B: BamHI; H: HindIII; M: MluI; P: PstI; R: EcoRI; S: SacI. Introduction of a frameshift mutation at the BamHI site in the second exon (denoted with an x) abrogated rescue by the minimal PstI-SacI rescuing fragment. Both splice variants, T07A5.6a and T07A5.6b, are contained within this fragment. (b) The UNC-69 protein sequence. The boxed region is predicted to form a coiled-coil domain. Arrows indicate the positions of the three known unc-69 mutations. Additional amino acids encoded by T07A5.6b are shown in italics (see Additional data file 1). (c) Northern-blot analysis of unc-69 revealed a single major transcript of 0.65 kb (arrow).

Mentions: Previous genetic data placed unc-69 between lin-12 and tra-1 on chromosome III, 0.12 map units to the left of ced-9 [19]. Using cosmid rescue, we were able to identify the predicted gene T07A5.6a (previously named T07C4.10b) as unc-69 (Figure 1a). The unc-69 gene encodes a 108-amino-acid protein and contains a short coiled-coil domain in its carboxyl terminus (Figure 1b). Although UNC-69 could possibly form a homodimer via its coiled-coil domain, we failed to detect any homophilic interactions of UNC-69 (see Additional data file 1).


The short coiled-coil domain-containing protein UNC-69 cooperates with UNC-76 to regulate axonal outgrowth and normal presynaptic organization in Caenorhabditis elegans.

Su CW, Tharin S, Jin Y, Wightman B, Spector M, Meili D, Tsung N, Rhiner C, Bourikas D, Stoeckli E, Garriga G, Horvitz HR, Hengartner MO - J. Biol. (2006)

The unc-69 locus encodes a 108-amino-acid protein with a short coiled-coil domain. (a) Genetic and physical maps of chromosome III in the vicinity of the unc-69 locus. unc-69 is close to and left of ced-9. Cosmids and subclones able to rescue the locomotion defect of unc-69(e587) mutants are shown in bold. B: BamHI; H: HindIII; M: MluI; P: PstI; R: EcoRI; S: SacI. Introduction of a frameshift mutation at the BamHI site in the second exon (denoted with an x) abrogated rescue by the minimal PstI-SacI rescuing fragment. Both splice variants, T07A5.6a and T07A5.6b, are contained within this fragment. (b) The UNC-69 protein sequence. The boxed region is predicted to form a coiled-coil domain. Arrows indicate the positions of the three known unc-69 mutations. Additional amino acids encoded by T07A5.6b are shown in italics (see Additional data file 1). (c) Northern-blot analysis of unc-69 revealed a single major transcript of 0.65 kb (arrow).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC1561584&req=5

Figure 1: The unc-69 locus encodes a 108-amino-acid protein with a short coiled-coil domain. (a) Genetic and physical maps of chromosome III in the vicinity of the unc-69 locus. unc-69 is close to and left of ced-9. Cosmids and subclones able to rescue the locomotion defect of unc-69(e587) mutants are shown in bold. B: BamHI; H: HindIII; M: MluI; P: PstI; R: EcoRI; S: SacI. Introduction of a frameshift mutation at the BamHI site in the second exon (denoted with an x) abrogated rescue by the minimal PstI-SacI rescuing fragment. Both splice variants, T07A5.6a and T07A5.6b, are contained within this fragment. (b) The UNC-69 protein sequence. The boxed region is predicted to form a coiled-coil domain. Arrows indicate the positions of the three known unc-69 mutations. Additional amino acids encoded by T07A5.6b are shown in italics (see Additional data file 1). (c) Northern-blot analysis of unc-69 revealed a single major transcript of 0.65 kb (arrow).
Mentions: Previous genetic data placed unc-69 between lin-12 and tra-1 on chromosome III, 0.12 map units to the left of ced-9 [19]. Using cosmid rescue, we were able to identify the predicted gene T07A5.6a (previously named T07C4.10b) as unc-69 (Figure 1a). The unc-69 gene encodes a 108-amino-acid protein and contains a short coiled-coil domain in its carboxyl terminus (Figure 1b). Although UNC-69 could possibly form a homodimer via its coiled-coil domain, we failed to detect any homophilic interactions of UNC-69 (see Additional data file 1).

Bottom Line: UNC-69 and UNC-76 colocalize as puncta in neuronal processes and cooperate to regulate axon extension and synapse formation.We have identified a novel protein complex, composed of UNC-69 and UNC-76, which promotes axonal growth and normal presynaptic organization in C. elegans.As both proteins are conserved through evolution, we suggest that the mammalian homologs of UNC-69 and UNC-76 (SCOCO and FEZ, respectively) may function similarly.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Molecular Biology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. chengwensu@gmail.com

ABSTRACT

Background: The nematode Caenorhabditis elegans has been used extensively to identify the genetic requirements for proper nervous system development and function. Key to this process is the direction of vesicles to the growing axons and dendrites, which is required for growth-cone extension and synapse formation in the developing neurons. The contribution and mechanism of membrane traffic in neuronal development are not fully understood, however.

Results: We show that the C. elegans gene unc-69 is required for axon outgrowth, guidance, fasciculation and normal presynaptic organization. We identify UNC-69 as an evolutionarily conserved 108-amino-acid protein with a short coiled-coil domain. UNC-69 interacts physically with UNC-76, mutations in which produce similar defects to loss of unc-69 function. In addition, a weak reduction-of-function allele, unc-69(ju69), preferentially causes mislocalization of the synaptic vesicle marker synaptobrevin. UNC-69 and UNC-76 colocalize as puncta in neuronal processes and cooperate to regulate axon extension and synapse formation. The chicken UNC-69 homolog is highly expressed in the developing central nervous system, and its inactivation by RNA interference leads to axon guidance defects.

Conclusion: We have identified a novel protein complex, composed of UNC-69 and UNC-76, which promotes axonal growth and normal presynaptic organization in C. elegans. As both proteins are conserved through evolution, we suggest that the mammalian homologs of UNC-69 and UNC-76 (SCOCO and FEZ, respectively) may function similarly.

Show MeSH
Related in: MedlinePlus