title: Preaxial polydactyly/triphalangeal thumb is associated with changed transcription factor-binding affinity in a family with a novel point mutation in the long-range cis-regulatory element ZRS.
abstract: A cis-regulatory sequence also known as zone of polarizing activity (ZPA) regulatory sequence (ZRS) located in intron 5 of LMBR1 is essential for expression of sonic hedgehog (SHH) in the developing posterior limb bud mesenchyme. Even though many point mutations causing preaxial duplication defects have been reported in ZRS, the underlying regulatory mechanism is still unknown. In this study, we analyzed the effect on transcription factor binding of a novel ZRS point mutation (463T>G) in a Pakistani family with preaxial polydactyly and triphalangeal thumb. Electrophoretical mobility shift assay demonstrated a marked difference between wild-type and the mutant probe, which uniquely bound one or several transcription factors extracted from Caco-2 cells. This finding supports a model in which ectopic anterior SHH expression in the developing limb results from abnormal binding of one or more transcription factors to the mutant sequence.
authors.affiliation: Human Molecular Genetics Laboratory, Health Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Farooq
authors.forename: Jesper T
authors.initials: JT
authors.lastname: Troelsen
authors.forename: Mette
authors.initials: M
authors.lastname: Boyd
authors.forename: Hans
authors.initials: H
authors.lastname: Eiberg
authors.forename: Lars
authors.initials: L
authors.lastname: Hansen
authors.forename: Muhammad Sajid
authors.initials: MS
authors.lastname: Hussain
authors.forename: Shoaib ur
authors.initials: Su
authors.lastname: Rehman
authors.forename: Aysha
authors.initials: A
authors.lastname: Azhar
authors.forename: Amjad
authors.initials: A
authors.lastname: Ali
authors.forename: Syeda Marriam
authors.initials: SM
authors.lastname: Bakhtiar
authors.forename: Niels
authors.initials: N
authors.lastname: Tommerup
authors.forename: Shahid Mahmood
authors.initials: SM
authors.lastname: Baig
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Kjaer
mesh_terms: D001483:Base Sequence; D018938:Caco-2 Cells; D005190:Family; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D010375:Pedigree; D017354:Point Mutation / Q000502:physiology; D017689:Polydactyly / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D050436:Regulatory Elements, Transcriptional / Q000235:genetics*; D013379:Substrate Specificity; D013933:Thumb / Q000002:abnormalities*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C485955:LMBR1 protein, human; D008565:Membrane Proteins; D014157:Transcription Factors