UMMS Affiliation

Program in Molecular Medicine

Publication Date


Document Type



Cell and Developmental Biology


The sensory and motility functions of cilia play critical roles in the development of vertebrates and defects in these organelles lead to a wide range of structural birth defects. The intraflagellar transport (IFT) system is required for building all types of mammalian cilia. IFT particles are composed of about 20 proteins and these proteins are highly conserved across ciliated species. IFT25 and IFT27, however, are absent from certain ciliated organisms like Caenorhabditis andDrosophila suggesting that they may have a unique role distinct from ciliogenesis. We generatedIft25 and Ift27 null mice and show that these proteins are not required for ciliary assembly but are required for proper Hedgehog signaling, which in mammals occurs within cilia. Mutant mice die at birth with multiple phenotypes indicative of Hedgehog signaling dysfunction. Cilia lacking IFT25/27 have defects in the signal-dependent transport of multiple Hedgehog components including Patched-1, Smoothened, and Gli2 and fail to activate the pathway upon stimulation. These are the first examples of null IFT mutations that perturb Hedgehog signaling independent of ciliary architecture. Thus, IFT function is not restricted to assembling cilia where signaling occurs but also plays a direct role in signal transduction events.

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© 2012 Pazour; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

DOI of Published Version



Cilia 2012, (Suppl 1):O9 doi:10.1186/2046-2530-1-S1-O9

Journal/Book/Conference Title