The rax homeobox gene is mutated in the eyeless axolotl, Ambystoma mexicanum. Dev Dyn 2021 Jun;250(6):807-821
Date
08/31/2020Pubmed ID
32864847Pubmed Central ID
PMC8907009DOI
10.1002/dvdy.246Scopus ID
2-s2.0-85090959056 (requires institutional sign-in at Scopus site) 4 CitationsAbstract
BACKGROUND: Vertebrate eye formation requires coordinated inductive interactions between different embryonic tissue layers, first described in amphibians. A network of transcription factors and signaling molecules controls these steps, with mutations causing severe ocular, neuronal, and craniofacial defects. In eyeless mutant axolotls, eye morphogenesis arrests at the optic vesicle stage, before lens induction, and development of ventral forebrain structures is disrupted.
RESULTS: We identified a 5-bp deletion in the rax (retina and anterior neural fold homeobox) gene, which was tightly linked to the recessive eyeless (e) axolotl locus in an F2 cross. This frameshift mutation, in exon 2, truncates RAX protein within the homeodomain (P154fs35X). Quantitative RNA analysis shows that mutant and wild-type rax transcripts are equally abundant in E/e embryos. Translation appears to initiate from dual start codons, via leaky ribosome scanning, a conserved feature among gnathostome RAX proteins. Previous data show rax is expressed in the optic vesicle and diencephalon, deeply conserved among metazoans, and required for eye formation in other species.
CONCLUSION: The eyeless axolotl mutation is a null allele in the rax homeobox gene, with primary defects in neural ectoderm, including the retinal and hypothalamic primordia.
Author List
Davis ES, Voss G, Miesfeld JB, Zarate-Sanchez J, Voss SR, Glaser TAuthor
Joel Bryan Miesfeld PhD Assistant Professor in the Ophthalmology and Visual Sciences department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Ambystoma mexicanumAnimals
Embryonic Development
Eye Proteins
Gene Expression Regulation, Developmental
Homeodomain Proteins
Mutation
Transcription Factors
