The monoamine neurotransmitter 5-hydroxytryptamine (5-HT, serotonin) is an essential component of the vertebrate central and autonomic nervous systems, regulating body temperature, sleep, appetite, and mood. Abnormal 5-HT signaling has been implicated in a variety of disorders such as depression, anxiety, alcoholism, obsessive-compulsive disorder (OCD) and autism. Synaptic concentrations of 5-HT are controlled through the activity of the presynaptic 5-HT transporter (5-HTT, SERT), a major target of psychostimulants and antidepressants, and which is regulated by multiple Ser/Thr kinase linked pathways. The C. elegans
mod-5 gene encodes a protein of the SLC6 gene family that possesses 49% amino acid sequence identity with mammalian SERT proteins and confers paroxetine-sensitive 5-HT transport on nonneuronal cells after heterologous expression (Ranganathan et. al., 2001). Here we report and characterize the expression of antidepressant-sensitive 5-HT transport in C. elegans primary embryonic cultures. These cultures allow us to quantify the impact of putative MOD-5 regulatory genes using lines deficient in known regulators of mammalian SERTs. Ongoing efforts also seek to evaluate the impact of
mod-5 alleles on 5-HT transport and turnover, as well as on nematode 5-HT/DA/GABA levels. We are currently generating transgenic lines expressing GFP:MOD-5 to study the enrichment of 5-HT transporters at serotonergic synapses in relation to other synaptic markers (e.g. CAT-1). Finally, we are pursuing both reverse and forward genetic manipulations to elucidate the structural/genetic determinants of MOD-5 trafficking, localization and transport activity. Supported by NIH award DA07390 and the Silvio O. Conte Center for Basic Neuroscience Research to RDB.