A twisted hand: bHLH protein phosphorylation and dimerization regulate limb development.
Saethre-Chotzen syndrome (SCS), a human autosomal dominant condition with limb defects and craniosynostosis, is caused by haploinsufficiency of TWIST1, a basic helix-loop-helix (bHLH) transcription factor. Until recently, the molecular pathogenesis of the limb defects in SCS has not been well understood. Now, Firulli et al.1 show in mouse and chick that ectopic expression of a related bHLH protein, Hand2, results in phenocopies of the limb defects caused by Twist1 loss-of-function mutations. These two proteins interact in a dosage-dependent antagonistic manner, and both can be regulated through phosphorylation at conserved helix I amino acid residues. These findings provide an important link between the misregulation of Twist1 dimerization and the limb phenotypes observed in SCS.
Cai
Juanliang
J
Institute of Genetic Medicine, Center for Craniofacial Development and Disorders, The Johns Hopkins University, Baltimore, MD 21205, USA. jcai@jhmi.edu
Jabs
Ethylin Wang
EW
D000818:Animals; D019281:Dimerization; D005121:Extremities / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D010766:Phosphorylation; D051879:Twist-Related Protein 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D051879:Twist-Related Protein 1