The UBR-1 ubiquitin ligase regulates glutamate metabolism to generate coordinated motor pattern in Caenorhabditis elegans
Fig 3
UBR-1 promotes body bending by preventing synchronized A motor neuron activation.
A) Diagram of connectivity of the C. elegans reversal motor circuit, drawn based on White et al. 1986 [45]. Hexagons and the circle denote premotor interneurons, and the A class motor neurons, respectively. Arrows and lines denote chemical and electrical synapses between neurons, respectively. B) Approximated anatomic positions of the three A class motor neurons (VA11, DA7, VA10) and their predicted ventral and dorsal muscle targets, drawn based on Haspel and Donovan, 2011 [79]. C) An example trace of simultaneous calcium imaging of three A-type motor neurons in a moving wildtype animal. Upper panel: activities of VA11, DA7, and VA10 neurons, reflected by the GCaMP6/RFP signal ratio (Upper panel); Lower panel: the instantaneous velocity of the animal, reflected by the displacement of DA7 soma position (Lower panel; positive values indicate moving towards the head; negative values indicate moving towards the tail), during a period of 40s from a 3min recording. Boxed period denotes the reversal period applied for cross-correlation analyses. C’) The cross-correlation of the activity profiles between VA10 and VA11 (left), VA10 and DA7 (center), and DA7 and VA11 (right), respectively. Dotted vertical line denotes the lag time. D, D’) An example trace of simultaneous calcium imaging (D) and cross-correlation analysis (D’) of VA11, DA7 and VA10 in a moving ubr-1 animal. E, E’) An example trace of simultaneous calcium imaging (E) and cross-correlation analysis (E’) of VA11, DA7 and VA10 in a moving transgenic ubr-1 mutant animal with restored UBR-1’s expression in neurons that include AVE/RIM premotor interneurons. F, F’) An example trace of simultaneous calcium imaging (F) and cross-correlation analysis (F’) of VA11, DA7 and VA10 in a moving ubr-1; got-1 mutant animal. G-I) The phase lags between activities of VA10 and VA11 (G), VA10 and DA7 (H), and DA7 and VA11 (I) in animals of respective genotypes. The asynchrony between VA10 and VA11 (G), and between VA10 and DA7 (H) are significantly reduced in ubr-1 mutants compared to wildtype animals, and restored in ubr-1 mutants by both UBR-1 expression in premotor interneurons, and the got-1 mutation. The activation of DA7 and VA11 (I), with higher synchrony than the other two pairs in wildtype animals, was not significantly altered in ubr-1 mutants. *P<0.05, **P<0.01, ***P<0.001 by the Kruskal-Wallis test. Horizontal lines represent mean values.