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Neurobiol Dis. 2015 Aug;80:15-28. doi: 10.1016/j.nbd.2015.05.008. Epub 2015 May 16.

A novel function of Huntingtin in the cilium and retinal ciliopathy in Huntington's disease mice.

Author information

1
Institute of Genetics and Molecular and Cellular Biology, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France.
2
Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University of Mainz, 55122 Mainz, Germany.
3
Centre de Génétique et de Physiologie Moléculaires et Cellulaires, CNRS UMR 5534, Université Claude Bernard Lyon 1, Villeurbanne, Lyon, 69622, France.
4
Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University of Mainz, 55122 Mainz, Germany; Focus Program Translational Neurosciences (FTN), Johannes Gutenberg University of Mainz, 55122 Mainz, Germany.
5
Institute of Genetics and Molecular and Cellular Biology, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France. Electronic address: Yvon.Trottier@igbmc.fr.

Abstract

Huntington's disease (HD) is a neurodegenerative disorder caused by the toxic expansion of polyglutamine in the Huntingtin (HTT) protein. The pathomechanism is complex and not fully understood. Increasing evidence indicates that the loss of normal protein function also contributes to the pathogenesis, pointing out the importance of understanding the physiological roles of HTT. We provide evidence for a novel function of HTT in the cilium. HTT localizes in diverse types of cilia--including 9 + 0 non-motile sensory cilia of neurons and 9 + 2 motile multicilia of trachea and ependymal cells--which exert various functions during tissue development and homeostasis. In the photoreceptor cilium, HTT is present in all subciliary compartments from the base of the cilium and adjacent centriole to the tip of the axoneme. In HD mice, photoreceptor cilia are abnormally elongated, have hyperacetylated alpha-tubulin and show mislocalization of the intraflagellar transport proteins IFT57 and IFT88. As a consequence, intraflagellar transport function is perturbed and leads to aberrant accumulation of outer segment proteins in the photoreceptor cell bodies and disruption of outer segment integrity, all of which precede overt cell death. Strikingly, endogenous mouse HTT is strongly reduced in cilia and accumulates in photoreceptor cell bodies, suggesting that HTT loss function contributes to structural and functional defects of photoreceptor cilia in HD mouse. Our results indicate that cilia pathology participates in HD physiopathology and may represent a therapeutic target.

KEYWORDS:

Cilia; Huntingtin; Huntington's disease; Photoreceptor

PMID:
25989602
DOI:
10.1016/j.nbd.2015.05.008
[Indexed for MEDLINE]

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