Rho is a presynaptic activator of neurotransmitter release at pre-existing synapses in C. elegans.
Rho GTPases have important roles in neuronal development, but their function in adult neurons is less well understood. We demonstrate that presynaptic changes in Rho activity at Caenorhabditis elegans neuromuscular junctions can radically change animal behavior via modulation of two separate pathways. In one, presynaptic Rho increases acetylcholine (ACh) release by stimulating the accumulation of diacylglycerol (DAG) and the DAG-binding protein UNC-13 at sites of neurotransmitter release; this pathway requires binding of Rho to the DAG kinase DGK-1. A second DGK-1-independent mechanism is revealed by the ability of a Rho inhibitor (C3 transferase) to decrease levels of release even in the absence of DGK-1; this pathway is independent of UNC-13 accumulation at release sites. We do not detect any Rho-induced changes in neuronal morphology or synapse number; thus, Rho facilitates synaptic transmission by a novel mechanism. Surprisingly, many commonly available human RhoA constructs contain an uncharacterized mutation that severely reduces binding of RhoA to DAG kinase. Thus, a role for RhoA in controlling DAG levels is likely to have been underestimated.
McMullan
Rachel
R
MRC Cell Biology Unit, MRC Laboratory for Molecular Cell Biology and Department of Pharmacology, University College, London WC1E 6BT, United Kingdom.
Hiley
Emma
E
Morrison
Paul
P
Nurrish
Stephen J
SJ
D036002:ADP Ribose Transferases / Q000378:metabolism; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D017173:Caenorhabditis elegans / Q000378:metabolism / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002352:Carrier Proteins; D002522:Chlorocebus aethiops; D019852:Diacylglycerol Kinase / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D009043:Motor Activity; D009469:Neuromuscular Junction / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D011485:Protein Binding; D015398:Signal Transduction; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission; D020741:rho GTP-Binding Proteins / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D004075:Diglycerides; C083141:phorbol ester binding protein; D036002:ADP Ribose Transferases; D019852:Diacylglycerol Kinase; D020741:rho GTP-Binding Proteins; D000109:Acetylcholine