RESUMEN
Human genomics is identifying candidate genes for congenital heart disease (CHD), but discovering the underlying mechanisms remains challenging. In a patient with CHD and heterotaxy (Htx), a disorder of left-right patterning, we previously identified a duplication in Nup188. However, a mechanism to explain how a component of the nuclear pore complex (NPC) could cause Htx/CHD was undefined. Here, we show that knockdown of Nup188 or its binding partner Nup93 leads to a loss of cilia during embryonic development while leaving NPC function largely intact. Many data, including the localization of endogenous Nup188/93 at cilia bases, support their direct role at cilia. Super-resolution imaging of Nup188 shows two barrel-like structures with dimensions and organization incompatible with an NPC-like ring, arguing against a proposed "ciliary pore complex." We suggest that the nanoscale organization and function of nucleoporins are context dependent in a way that is required for the structure of the heart.
Asunto(s)
Cardiopatías Congénitas/metabolismo , Síndrome de Heterotaxia/genética , Proteínas de Complejo Poro Nuclear/metabolismo , Proteínas de Xenopus/genética , Animales , Cilios/genética , Cilios/patología , Técnicas de Silenciamiento del Gen , Genoma Humano , Cardiopatías Congénitas/genética , Cardiopatías Congénitas/patología , Síndrome de Heterotaxia/patología , Humanos , Poro Nuclear/genética , Poro Nuclear/metabolismo , Proteínas de Complejo Poro Nuclear/química , Proteínas de Complejo Poro Nuclear/genética , Conformación Proteica , Mapas de Interacción de Proteínas/genética , Transporte de Proteínas/genética , Xenopus/genética , Proteínas de Xenopus/química , Proteínas de Xenopus/metabolismoRESUMEN
Nucleoporins (nups) compose the structure of the nuclear pore complex (NPC) of all cells, but several studies have illuminated nucleoporins' additional roles in development and the cell cycle. However, a comprehensive study of nup expression in embryonic development has not yet been reported. We synthesized antisense probes for all nup genes and used whole-mount in situ hybridization techniques to determine the expression pattern of all members of the nup family of genes at three different developmental stages in Xenopus tropicalis. We found that the expression of nups was not ubiquitous in embryos, but was localized to specific and distinguishable anatomical structures at all three stages tested. We also found that the expression patterns for nups within the same subcomplexes were not necessarily identical. Thus, nup expression is subject to a significant level of regulation during development. These results provide new information for functional studies of nups to unravel their roles in embryonic development.
