Presynaptic SNAP-25 regulates retinal waves and retinogeniculate projection via phosphorylation
Journal
Proceedings of the National Academy of Sciences of the United States of America
Journal Volume
116
Journal Issue
8
Pages
3262-3267
Date Issued
2019-02-19
Author(s)
Hsiao, Yu Tien
Shu, Wen Chi
Chen, Pin Chun
Yang, Hui Ju
Chen, Hsin Yo
Hsu, Sheng Ping
Huang, Yi Ting
Yang, Cheng Chang
Chen, Yen Ju
Yu, Ni Yen
Liou, Shih Yuan
Chiang, Ning
Huang, Chien Ting
Cheng, Tzu Lin
Cheung, Lam Yan
Lin, Yu Chun
Lu, Juu Chin
Abstract
© 2019 National Academy of Sciences. All Rights Reserved. Patterned spontaneous activity periodically displays in developing retinas termed retinal waves, essential for visual circuit refinement. In neonatal rodents, retinal waves initiate in starburst amacrine cells (SACs), propagating across retinal ganglion cells (RGCs), further through visual centers. Although these waves are shown temporally synchronized with transiently high PKA activity, the downstream PKA target important for regulating the transmission from SACs remains unidentified. A t-SNARE, synaptosome-associated protein of 25 kDa (SNAP-25/SN25), serves as a PKA substrate, implying a potential role of SN25 in regulating retinal development. Here, we examined whether SN25 in SACs could regulate wave properties and retinogeniculate projection during development. In developing SACs, overexpression of wild-type SN25b, but not the PKA-phosphodeficient mutant (SN25b-T138A), decreased the frequency and spatial correlation of wave-associated calcium transients. Overexpressing SN25b, but not SN25b-T138A, in SACs dampened spontaneous, wave-associated, postsynaptic currents in RGCs and decreased the SAC release upon augmenting the cAMP-PKA signaling. These results suggest that SN25b overexpression may inhibit the strength of transmission from SACs via PKA-mediated phosphorylation at T138. Moreover, knockdown of endogenous SN25b increased the frequency of wave-associated calcium transients, supporting the role of SN25 in restraining wave periodicity. Finally, the eye-specific segregation of retinogeniculate projection was impaired by in vivo overexpression of SN25b, but not SN25b-T138A, in SACs. These results suggest that SN25 in developing SACs dampens the spatiotemporal properties of retinal waves and limits visual circuit refinement by phosphorylation at T138. Therefore, SN25 in SACs plays a profound role in regulating visual circuit refinement.
Subjects
PKA-mediated phosphorylation | Retinal waves | Retinogeniculate projection | SNAP-25 | Starburst amacrine cells
Publisher
NATL ACAD SCIENCES
Type
journal article