Loss of Bardet-Biedl syndrome proteins alters the morphology and function of motile cilia in airway epithelia.
Mutations in a group of genes that contribute to ciliary function cause Bardet-Biedl syndrome (BBS). Most studies of BBS have focused on primary, sensory cilia. Here, we asked whether loss of BBS proteins would also affect motile cilia lining the respiratory tract. We found that BBS genes were expressed in human airway epithelia, and BBS2 and BBS4 localized to cellular structures associated with motile cilia. Although BBS proteins were not required for ciliogenesis, their loss caused structural defects in a fraction of cilia covering mouse airway epithelia. The most common abnormality was bulges filled with vesicles near the tips of cilia. We discovered this same misshapen appearance in airway cilia from Bbs1, Bbs2, Bbs4, and Bbs6 mutant mice. The structural abnormalities were accompanied by functional defects; ciliary beat frequency was reduced in Bbs mutant mice. Previous reports suggested BBS might increase the incidence of asthma. However, compared with wild-type controls, neither airway hyperresponsiveness nor inflammation increased in Bbs2(-/-) or Bbs4(-/-) mice immunized with ovalbumin. Instead, these animals were partially protected from airway hyperresponsiveness. These results emphasize the role of BBS proteins in both the structure and function of motile cilia. They also invite additional scrutiny of motile cilia dysfunction in patients with this disease.
Shah
Alok S
AS
Departments of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
Farmen
Sara L
SL
Moninger
Thomas O
TO
Businga
Thomas R
TR
Andrews
Michael P
MP
Bugge
Kevin
K
Searby
Charles C
CC
Nishimura
Darryl
D
Brogden
Kim A
KA
Kline
Joel N
JN
Sheffield
Val C
VC
Welsh
Michael J
MJ
D000818:Animals; D020788:Bardet-Biedl Syndrome / Q000473:pathology*; D048430:Cell Shape; D002923:Cilia / Q000737:chemistry / Q000473:pathology* / Q000502:physiology; D056385:Group II Chaperonins; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D018832:Molecular Chaperones / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D020545:Respiratory Mucosa / Q000473:pathology*
C429655:BBS4 protein, human; C506281:BBS4 protein, mouse; C506280:Bbs1 protein, mouse; C473309:Bbs2 protein, human; D008869:Microtubule-Associated Proteins; C506279:Mkks protein, mouse; D018832:Molecular Chaperones; D011506:Proteins; D056385:Group II Chaperonins