Temtamy preaxial brachydactyly syndrome is caused by loss-of-function mutations in chondroitin synthase 1, a potential target of BMP signaling.
Altered Bone Morphogenetic Protein (BMP) signaling leads to multiple developmental defects, including brachydactyly and deafness. Here we identify chondroitin synthase 1 (CHSY1) as a potential mediator of BMP effects. We show that loss of human CHSY1 function causes autosomal-recessive Temtamy preaxial brachydactyly syndrome (TPBS), mainly characterized by limb malformations, short stature, and hearing loss. After mapping the TPBS locus to chromosome 15q26-qterm, we identified causative mutations in five consanguineous TPBS families. In zebrafish, antisense-mediated chsy1 knockdown causes defects in multiple developmental processes, some of which are likely to also be causative in the etiology of TPBS. In the inner ears of zebrafish larvae, chsy1 is expressed similarly to the BMP inhibitor dan and in a complementary fashion to bmp2b. Furthermore, unrestricted Bmp2b signaling or loss of Dan activity leads to reduced chsy1 expression and, during epithelial morphogenesis, defects similar to those that occur upon Chsy1 inactivation, indicating that Bmp signaling affects inner-ear development by repressing chsy1. In addition, we obtained strikingly similar zebrafish phenotypes after chsy1 overexpression, which might explain why, in humans, brachydactyly can be caused by mutations leading either to loss or to gain of BMP signaling.
Center for Molecular Medicine Cologne, University of Cologne, Germany.
Yun
Y
Li
Kathrin
K
Laue
Samia
S
Temtamy
Mona
M
Aglan
L Damla
LD
Kotan
Gökhan
G
Yigit
Husniye
H
Canan
Barbara
B
Pawlik
Gudrun
G
Nürnberg
Emma L
EL
Wakeling
Oliver W
OW
Quarrell
Ingelore
I
Baessmann
Matthew B
MB
Lanktree
Mustafa
M
Yilmaz
Robert A
RA
Hegele
Khalda
K
Amr
Klaus W
KW
May
Peter
P
Nürnberg
A Kemal
AK
Topaloglu
Matthias
M
Hammerschmidt
Bernd
B
Wollnik
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D059327:Brachydactyly; D002874:Chromosome Mapping; D002884:Chromosomes, Human, Pair 15; D005532:Foot Deformities, Congenital / Q000235:genetics; D006228:Hand Deformities, Congenital / Q000235:genetics; D006801:Humans; D009154:Mutation; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D013577:Syndrome; D015027:Zebrafish
D019485:Bone Morphogenetic Proteins; D017350:N-Acetylgalactosaminyltransferases; C412725:chondroitin synthase