Intracerebroventricular antisense knockdown of Gαi2 results in ciliary stasis and ventricular dilatation in the rat

Kati S Mönkkönen,Robert A Hirst,Jarmo T Laitinen,Juhana M Hakumäki,Pekka T Männistö,Christopher O'Callaghan,Riitta A Miettinen

doi:10.1186/1471-2202-8-26

Kati S Mönkkönen, Robert A Hirst + Show 5 more

Open Access

https://doi.org/10.1186/1471-2202-8-26

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Abstract

BackgroundIn the CNS, the heterotrimeric G protein Gαi2 is a minor Gα subunit with restricted localization in the ventricular regions including the ependymal cilia. The localization of Gαi2 is conserved in cilia of different tissues, suggesting a particular role in ciliary function. Although studies with Gαi2-knockout mice have provided information on the role of this Gα subunit in peripheral tissues, its role in the CNS is largely unknown. We used intracerebroventricular (icv) antisense administration to clarify the physiological role of Gαi2 in the ventricular system.ResultsHigh resolution MRI studies revealed that continuous icv-infusion of Gαi2-specific antisense oligonucleotide caused unilateral ventricular dilatation that was restricted to the antisense-receiving ventricle. Microscopic analysis demonstrated ependymal cell damage and loss of ependymal cilia. Attenuation of Gαi2 in ependymal cells was confirmed by immunohistochemistry. Ciliary beat frequency measurements on cultured ependymal cells indicated that antisense administration resulted in ciliary stasis.ConclusionOur results establish that Gαi2 has an essential regulatory role in ciliary function and CSF homeostasis.

Highlights

In the CNS, the heterotrimeric G protein Gαi2 is a minor Gα subunit with restricted localization in the ventricular regions including the ependymal cilia
In order to evaluate the effects of ASODN treatment on behavior, the animals were tested for motor coordination, anxiety, motor activity as well as for pain perception and morphine analgesia
Our results indicate that Gαi2 has an essential and previously unrecognized regulatory role in ciliary function and cerebrospinal fluid (CSF) homeostasis

Summary

Introduction

In the CNS, the heterotrimeric G protein Gαi is a minor Gα subunit with restricted localization in the ventricular regions including the ependymal cilia. Gαi is localized in the subventricular zone, the rostral migratory stream [4], the accessory olfactory bulb [5] and the ependymal cilia [6]. Such a specific localization implies that Gαi may well subserve physiological function distinct from those of the other Gα subunits. Gαi is present in motile cilia which have a characteristic 9+2 ultrastructure in different peripheral tissues, such as rat oviduct and trachea [6] This may mean that the Gαi subunit plays a specific, regulatory role in ciliary function. These immunohistochemical findings were further supported by the proteomic analysis which revealed that Gαi is a resident axonemal protein of the human bronchial cilia [7]

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