Martín M. Riccomagno, Andrés Hurtado, HongBin Wang, Joshua G.J. Macopson, Erin M. Griner, Andrea Betz, Nils Brose, Marcelo G. Kazanietz, Alex L. Kolodkin. (2012).  The RacGAP β2-Chimaerin Selectively Mediates Axonal Pruning in the Hippocampus. Cell, 149, 1594-1606.

The RacGAP βChimaerin (βChn) acts downstream of the secreted repulsive cue Sema3F to inhibit the small GTPase Rac1, thereby promoting hippocampal Infrapyramidal Tract  (IPT) pruning.  The image shows that β2Chn is required in the dentate gyrus (DG) for IPT pruning in vivo (compare IPT length (arrowheads) in mice that express Chn2-shRNA (right) or control shRNA (left) in the DG). β2Chn is essential for Sema3F-mediated axon pruning, but not for Sema3F-mediated axon guidance or constraint of dendritic spine number.  This differential requirement for ßChn provides insight into the mechanistic distinctions underlying critical inhibitory events that regulate neuronal morphology and are controlled by the same ligand.