Behavioural phenotyping of ubiquitous LRIG 2 knockout mice

The study of the leucine-rich repeat and immunoglobuline-like domains (LRIG), family of proteins is in its infancy. Especially LRIG2 has not yet been extensively investigated. Considering this and due to LRIG2 differing slightly in its intra- and extracellular structure in comparison to the other proteins in this family we decided to investigate this particular protein. We generated ubiquitous LRIG2-knockout mice, screened them for behavioral differences in comparison to their wildtype littermates and tried to relate these to specific brain regions to improve the understanding of LRIG2’s role in the brain and in learning processes. Behavioral screening focused on four aspects: anxiety, sensory-motor gating, spatial memory/learning and sense of smell. Anxiety was evaluated with the open field test, the elevated plus maze as well as with the three-chamber social interaction test. Sensory-motor gating was investigated via the startle and prepuls-inhibition test. Learning and memory was assessed with the Morris water maze, the Y-maze and fear conditioning. In addition, sense and memory of smell was assessed via the olfactory habitation/dishabituation test with nonsocial odours. Subsequently histopathological analysis of the brain was performed by an external laboratory. Results of our behavioral screening suggests that predominantly amygdala dependent processes such as emotional learning/memory and sensory-motor gating are impeded by the ubiquitous knockout of LRIG2 in mice. Furthermore, as there were no differences in the histopathological analysis discovered, we assume that these impairments are caused by pathway interruptions in which LRIG2 plays an important role. Therefore, we assume that future research of LRIG2 pathways and their interaction with the amygdala may lead to better understanding of the role of LRIG2 in the brain.