Figure 1. OIG-1 Inhibits Postsynaptic Remodeling of DD Motor Neurons(A) Embryonic DD motor neurons innervate ventral muscles and extend commissures to the dorsal side for input from cholinergic motor neurons. Toward the endof the L1 larval stage, presynaptic vesicles (red) and postsynaptic acetylcholine receptors (AChRs) (green) switch locations as DDs remodel.(B) In a newly hatched L1 larva, RAB-3::mCherry (red) marks DD synapses with ventral muscle, and ACR-12::GFP (green) labels postsynaptic DD regions in thedorsal nerve cord. In an L4 larva, presynaptic RAB-3::mCherry (red) labels DD inputs to dorsal muscles and ACR-12::GFP (green) is restricted to ventral DDpostsynaptic locations. Asterisk denotes gut autofluorescence. Scale bars, 5 um.(C) ACR-12::GFP AChR subunits are dorsally localized in early L1 DD motor neurons but are strictly ventral by the L4 larval stage. Scale bars, 5 um.(D) The
oig-1 gene includes three exons (black boxes) with a canonical N-terminal signal peptide (SP) sequence. Exons 2 and 3 are deleted in
oig-1(
ok1687).(E) The OIG-1 protein includes an N-terminal signal peptide (SP) and a single immunoglobulin (Ig) domain.(F) Quantification of dorsal ACR-12::GFP fluorescenceintensity comparing wild-type and
oig1(ok1687) L2 and L4 larvae. ***p < 0.001, Student's t-test, n > 15 for each group. Error bars, SD.(G) Representative images of dorsal ACR-12::GFP puncta in wild-type and
oig-1 mutant L1 animals (4 hr post-hatch). Scale bar, 5 um.(H) Quantification of ACR-12::GFP localization in the dorsal nerve cord detects a weaker signal in
oig1 mutants than in wild-type at 4 hr post-hatch.****p < 0.0001 versus wild-type. n = 10 for eachgroup, Student's t test. Error bars, SEM.