Multiple domains in the Crumbs Homolog 2a (Crb2a) protein are required for regulating rod photoreceptor size

BMC Cell Biology

Research Article

Abbie M Jensen¹  Ya-Chu Hsu² 

[1] Department of Biology, University of Massachusetts, 01003, Amherst, MA, USA;Molecular and Cellular Biology Program, University of Massachusetts, 01003, Amherst, MA, USA;Department of Biology, University of Massachusetts, 01003, Amherst, MA, USA;Molecular and Cellular Biology Program, University of Massachusetts, 01003, Amherst, MA, USA;Department of Ophthalmology, Margaret M. Dyson Research Institute, Weill Cornell Medical College, 10021, NYC, NY, USA;

关键词: Extracellular Domain;    Outer Segment;    Vertebrate Photoreceptor;    Drosophila Photoreceptor;    Outer Limit Membrane;   

DOI  :  10.1186/1471-2121-11-60

 received in 2009-10-14, accepted in 2010-07-29,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundVertebrate retinal photoreceptors are morphologically complex cells that have two apical regions, the inner segment and the outer segment. The outer segment is a modified cilium and is continuously regenerated throughout life. The molecular and cellular mechanisms that underlie vertebrate photoreceptor morphogenesis and the maintenance of the outer segment are largely unknown. The Crumbs (Crb) complex is a key regulator of apical membrane identity and size in epithelia and in Drosophila photoreceptors. Mutations in the human gene CRUMBS HOMOLOG 1 (CRB1) are associated with early and severe vision loss. Drosophila Crumbs and vertebrate Crb1 and Crumbs homolog 2 (Crb2) proteins are structurally similar, all are single pass transmembrane proteins with a large extracellular domain containing multiple laminin- and EGF-like repeats and a small intracellular domain containing a FERM-binding domain and a PDZ-binding domain. In order to begin to understand the role of the Crb family of proteins in vertebrate photoreceptors we generated stable transgenic zebrafish in which rod photoreceptors overexpress full-length Crb2a protein and several other Crb2a constructs engineered to lack specific domains.ResultsWe examined the localization of Crb2a constructs and their effects on rod morphology. We found that only the full-length Crb2a protein approximated the normal localization of Crb2a protein apical to adherens junctions in the photoreceptor inner segment. Several Crb2a construct proteins localized abnormally to the outer segment and one construct localized abnormally to the cell body. Overexpression of full-length Crb2a greatly increased inner segment size while expression of several other constructs increased outer segment size.ConclusionsOur observations suggest that particular domains in Crb2a regulate its localization and thus may regulate its regionalized function. Our results also suggest that the PDZ-binding domain in Crb2a might bring a protein(s) into the Crb complex that alters the function of the FERM-binding domain.

【 授权许可】

CC BY   
© Hsu and Jensen; licensee BioMed Central Ltd. 2010