Jiangxi Province, China
Bachelor in Medicine
Shanghai Medical College, Fudan University
Neural circuits are constantly remodeled during development; however, the mechanisms underlying this process and the timing of rewiring remain largely unknown. The Dorsal D (DD) GABAergic motor neurons of C. elegans undergo extensive remodeling during development. At the end of the first larval stage (L1), synapses of DD motor neurons that initially innervate ventral muscle are removed and new synapses are formed on dorsal muscles. This remodeling program is blocked in Ventral D (VD) GABAergic motor neurons by the COUP-TF homolog, UNC-55. Thus, VD synapses to muscle remain on the ventral side. Previous studies have focused on mechanisms that drive the relocation of presynaptic components in GABA neurons but had not confirmed that the postsynaptic apparatus is also remodeled. We hypothesize that postsynaptic components of GABAergic motor neurons also remodel and this process is transcriptionally regulated. To address this question, we tagged the non-α subunit of the acetylcholine receptor, ACR-12 with green fluorescence protein (GFP). We showed that the postsynaptic marker ACR-12::GFP is localized contralaterally with its presynaptic counterparts, and that it remodels in DD neurons during the late L1 stage. We found that UNC-55 inhibits the postsynaptic remodeling program in VD neurons. Using cell-specific RNA interference (RNAi), we demonstrated that a downstream target of UNC-55, the Iroquois-like homeodomain protein, IRX-1 is also required for postsynaptic remodeling. The well-established roles of these conserved transcription factors in mammalian neural development suggest that a similar cascade may also control synaptic plasticity in more complex nervous systems.