The BBSome (so-named after the association with Bardet-Biedl syndrome) is a complex of 8 subunits that lies at the base of the flagellar microtubule structure. The precise function of the all the individual components in cilia formation is unclear, however they function to promote loading of cargo to the ciliary axoneme [1]. The primary cilium, a slim microtubule-based organelle that projects from the surface of vertebrate cells has crucial roles in vertebrate development and human genetic diseases. Cilia are required for the response to developmental signals, and evidence is accumulating that the primary cilium is specialised for Hedgehog (Hh) signal transduction. Formation of cilia, in turn, is regulated by other signalling pathways, possibly including the planar cell polarity pathway. The connections between cilia and developmental signalling have begun to clarify the basis of human diseases associated with ciliary dysfunction [3]. BBS2 is one of the three Bardet-Biedl syndrome subunits that is required for leptin receptor signalling in the hypothalamus, and BBS2 and 4 are also required for the localisation of somatostatin receptor 3 and melanin-concentrating hormone receptor 1 into neuronal cilia [5].

1: A core complex of BBS proteins cooperates with the GTPase Rab8 to promote ciliary membrane biogenesis. Nachury MV, Loktev AV, Zhang Q, Westlake CJ, Peranen J, Merdes A, Slusarski DC, Scheller RH, Bazan JF, Sheffield VC, Jackson PK; Cell. 2007;129:1201-1213. PMID:17574030

2: A BBSome subunit links ciliogenesis, microtubule stability, and acetylation. Loktev AV, Zhang Q, Beck JS, Searby CC, Scheetz TE, Bazan JF, Slusarski DC, Sheffield VC, Jackson PK, Nachury MV; Dev Cell. 2008;15:854-865. PMID:19081074

3: The primary cilium: a signalling centre during vertebrate development. Goetz SC, Anderson KV; Nat Rev Genet. 2010;11:331-344. PMID:20395968

4: Patterns of expression of Bardet-Biedl syndrome proteins in the mammalian cochlea suggest noncentrosomal functions. The primary cilium: a signalling centre during vertebrate development. Goetz SC, Anderson KV;RL\t Nat Rev Genet. 2010;11:331-344. Nat Rev Genet. 2010;11:331-344. PMID:19396898

5: Bardet-Biedl syndrome proteins are required for the localization of G protein-coupled receptors to primary cilia. Berbari NF, Lewis JS, Bishop GA, Askwith CC, Mykytyn K; Proc Natl Acad Sci U S A. 2008;105:4242-4246. PMID:18334641