It was reported that some proteins known to cause renal cystic disease (NPHP6;
BBS1, and BBS4) also localize to the olfactory epithelium (OE), and that
mutations in these proteins can cause anosmia in addition to renal cystic
disease. We demonstrate here that a number of other proteins associated with
renal cystic diseases – polycystin 1 and 2 (PC1, PC2), and Meckel-Gruber
syndrome 1 and 3 (MKS1, MKS3) – localize to the murine OE. PC1, PC2, MKS1
and MKS3 are all detected in the OE by RT-PCR. We find that MKS3 localizes
specifically to dendritic knobs of olfactory sensory neurons (OSNs), while PC1
localizes to both dendritic knobs and cilia of mature OSNs. In mice carrying
mutations in MKS1, the expression of the olfactory adenylate
cyclase (AC3) is substantially reduced. Moreover, in rats with renal cystic
disease caused by a mutation in MKS3, the laminar organization
of the OE is perturbed and there is a reduced expression of components of the
odor transduction cascade (Golf, AC3) and α-acetylated tubulin.
Furthermore, we show with electron microscopy that cilia in
MKS3 mutant animals do not manifest the proper microtubule
architecture. Both MKS1 and MKS3 mutant
animals show no obvious alterations in odor receptor expression. These data show
that multiple renal cystic proteins localize to the OE, where we speculate that
they work together to regulate aspects of the development, maintenance or
physiological activities of cilia.