Abstract

Leukocyte common antigen-related receptor tyrosine phosphatases (LAR-RPTPs) are evolutionarily conserved presynaptic organizers. The synaptic role of vertebrate LAR-RPTPs in vivo, however, remains unclear. This study systematically analyzed the effects of genetic deletions of LAR-RPTP genes by generating single conditional knockout (cKO) mice targeting PTP{sigma} and PTP{delta}. Although the numbers of synapses were reduced in cultured neurons deficient in individual PTPs, abnormalities in synaptic transmission, synaptic ultrastructures, and vesicle localization were observed only in PTP{sigma}-deficient neurons. Strikingly, loss of presynaptic PTP{sigma} reduced neurotransmitter release prominently at excitatory synapses, concomitant with drastic reductions in excitatory innervations onto postsynaptic target areas in vivo. However, postsynaptic PTP{sigma} deletion had no effect on excitatory synaptic strength. Furthermore, conditional deletion of PTP{sigma} in ventral CA1 specifically altered anxiety-like behaviors. Taken together, these results demonstrate that PTP{sigma} is a bona fide presynaptic adhesion molecule that controls neurotransmitter release and excitatory inputs.