title: Paired-related homeobox genes cooperate in handplate and hindlimb zeugopod morphogenesis.
abstract: The closely related homeobox genes prx-1 and prx-2 are expressed in lateral plate and limb bud mesoderm, but targeted inactivation of these genes failed to demonstrate a limb phenotype. Here we report that mice carrying compound mutations in prx-1 and prx-2 have severe limb deformities. In the forelimb autopod, pre- and postaxial polydactyly were found most commonly, but also syndactyly, oligodactyly, and abnormal digit placement affecting posterior elements were observed. In the hindlimb, preaxial polydactyly with variable expressivity was seen in all cases. Extreme distal digit duplications were seen in both the fore- and hindlimbs. prx-1; prx-2 double-mutant mice also displayed extreme shortening and impaired ossification of the hindlimb zeugopods. Integrity of the forelimb apical ectodermal ridge was abnormal as determined by expression of FGF8 and BMP4. Expression of msx-1 and msx-2, markers for BMP signaling pathways, was absent in regions of the posterior handplates, while expression of Shh and patched was unaffected. The mutant phenotypes were dosage dependent, since prx-1 -/-; prx-2 +/- mice also displayed severe limb abnormalities. These data suggest that prx-1 and prx-2 cooperatively regulate handplate and hindlimb zeugopod morphogenesis through BMP-mediated signaling pathways.
authors.affiliation: Center for Cancer Biology and Nutrition, Texas A & M University, Houston, Texas, 77030-3303, USA.
authors.forename: M F
authors.initials: MF
authors.lastname: Lu
authors.forename: H T
authors.initials: HT
authors.lastname: Cheng
authors.forename: A R
authors.initials: AR
authors.lastname: Lacy
authors.forename: M J
authors.initials: MJ
authors.lastname: Kern
authors.forename: E A
authors.initials: EA
authors.lastname: Argao
authors.forename: S S
authors.initials: SS
authors.lastname: Potter
authors.forename: E N
authors.initials: EN
authors.lastname: Olson
authors.forename: J F
authors.initials: JF
authors.lastname: Martin
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005552:Forelimb / Q000002:abnormalities* / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D006614:Hindlimb / Q000002:abnormalities* / Q000196:embryology; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D018878:Limb Buds / Q000502:physiology*; D051957:MSX1 Transcription Factor; D008648:Mesoderm / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009024:Morphogenesis; D014157:Transcription Factors
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051957:MSX1 Transcription Factor; C084119:MSX2 protein; C489936:Prrx1 protein, mouse; C115469:Prrx2 protein, mouse; D014157:Transcription Factors