Sept6 Is Required for Ciliogenesis in Kupffer's Vesicle, the Pronephros, and the Neural Tube during Early Embryonic Development

Abstract

Septins are conserved filament-forming GTP-binding proteins that act as cellular scaffolds or diffusion barriers in a number of cellular processes. However, the role of septins in vertebrate development remains relatively obscure. Here, we show that zebrafish septin 6 (sept6) is first expressed in the notochord and then in nearly all of the ciliary organs, including Kupffer's vesicle (KV), the pronephros, eye, olfactory bulb, and neural tube. Knockdown of sept6 in zebrafish embryos results in reduced numbers and length of cilia in KV. Consequently, cilium-related functions, such as the left-right patterning of internal organs and nodal/spaw signaling, are compromised. Knockdown of sept6 also results in aberrant cilium formation in the pronephros and neural tube, leading to cilium-related defects in pronephros development and Sonic hedgehog (Shh) signaling. We further demonstrate that SEPT6 associates with acetylated α-tubulin in vivo and localizes along the axoneme in the cilia of zebrafish pronephric duct cells as well as cultured ZF4 cells. Our study reveals a novel role of sept6 in ciliogenesis during early embryonic development in zebrafish.

ACKNOWLEDGMENTS

We thank Julia Hanna for carefully reading the manuscript.

Work in the Yin lab was supported by the National Basic Research Program of China (973 Program, 2010CB126302) and the National Natural Science Foundation of China (30925027 and 30871402). Work in the Bi lab was supported by grants GM59216 and GM87365 from the U.S. National Institutes of Health.