Abstract
To gain insight into synapse development, research has mostly focused on glutamatergic synapses. Only in recent years have research studies started to specifically address GABAergic synapse development. Therefore, deeper insight into the molecular mechanisms of GABAergic synapse development is still missing. How closely both synapse types resemble each other in their underlying molecular mechanisms is unclear. Although research studies have already revealed some similarities, there are also clear differences in glutamatergic and GABAergic synapse development. The small GTPase Rem2 has been identified in a genetic screen as a regulator for glutamatergic as well as GABAergic synapse development. In addition, another study has revealed that binding of Rem2 to the calcium sensor calmodulin is not required for its positive regulation of glutamatergic synapse development, as opposed to the role of Rem2 in regulation of dendritic morphology. These findings led to the intriguing question of what is the role of Rem2 in GABAergic synapse development. This thesis sought to address this question, specifically if binding of Rem2 to calmodulin or GTP is required for effects on GABAergic synapse development. A rat hippocampal neuron culture system and RNAi technology was used to address these questions by evaluating GABAergic synapse density. Because initial experiments gave inconsistent results of Rem2 RNAi effects on GABAergic synapse density, no interpretation of results on Rem2 binding requirements could be done. To address these puzzling results, a reevaluation of experimental procedures was done. Several approaches of reevaluation including reproducing Rem2 RNAi results on excitatory synapse density were done. These led to improvements in experimental procedure. In addition, a possible dominant negative effect on GABAergic synapse density when Rem2 is overexpressed by RNAi-resistant Rem2 cDNA can be proposed as a novel function of Rem2. Unfortunately, the question of a role of Rem2 in GABAergic synapse development and potential requirement of binding to calmodulin or GTP remains to be determined.