TY - JOUR T1 - Guidance-Cue Control of Horizontal Cell Morphology, Lamination, and Synapse Formation in the Mammalian Outer Retina JF - The Journal of Neuroscience JO - J. Neurosci. SP - 6859 LP - 6868 DO - 10.1523/JNEUROSCI.0267-12.2012 VL - 32 IS - 20 AU - Ryota L. Matsuoka AU - Zheng Jiang AU - Ivy S. Samuels AU - Kim T. Nguyen-Ba-Charvet AU - Lu O. Sun AU - Neal S. Peachey AU - Alain Chédotal AU - King-Wai Yau AU - Alex L. Kolodkin Y1 - 2012/05/16 UR - http://www.jneurosci.org/content/32/20/6859.abstract N2 - In the vertebrate retina, neuronal circuitry required for visual perception is organized within specific laminae. Photoreceptors convey external visual information to bipolar and horizontal cells at triad ribbon synapses established within the outer plexiform layer (OPL), initiating retinal visual processing. However, the molecular mechanisms that organize these three classes of neuronal processes within the OPL, thereby ensuring appropriate ribbon synapse formation, remain largely unknown. Here we show that mice with null mutations in Sema6A or PlexinA4 (PlexA4) exhibit a pronounced defect in OPL stratification of horizontal cell axons without any apparent deficits in bipolar cell dendrite or photoreceptor axon targeting. Furthermore, these mutant horizontal cells exhibit aberrant dendritic arborization and reduced dendritic self-avoidance within the OPL. Ultrastructural analysis shows that the horizontal cell contribution to rod ribbon synapse formation in PlexA4−/− retinas is disrupted. These findings define molecular components required for outer retina lamination and ribbon synapse formation. ER -