ABSTRACT
Photoreceptors are organized at the outer aspect of retina and host the process of phototransduction, central to the visual system. We have isolated a novel human gene, RZF, which is predominantly expressed in the photoreceptors of human retina. RZF encodes a 40-kDa protein that has three widely spaced C(2)H(2)-type zinc finger motifs. There are three potential nuclear localisation signals and clusters of charged amino acids in the protein. Expression analysis revealed that orthologues of the RZF gene are also expressed in photoreceptors of mouse and bovine retina. The RZF-GFP fusion protein localises to nucleoli and cytoplasm when expressed in HEK-293 cells. Mobility shift assay suggests that RZF may not be a nucleic acid binding protein, unlike most other zinc-finger proteins. Taken together, these observations suggest that RZF is a shuttling regulatory protein expressed in photoreceptors of the human retina that may be involved in mRNA or protein regulation of photoreceptor-specific genes and therefore have role in retinal disease mechanisms.
Subject(s)
DNA-Binding Proteins/genetics , Photoreceptor Cells/metabolism , Zinc Fingers/genetics , Amino Acid Sequence , Animals , Base Sequence , Binding Sites/genetics , Blotting, Western , Cattle , Cell Line , Cloning, Molecular , DNA, Complementary/chemistry , DNA, Complementary/genetics , DNA, Single-Stranded/metabolism , DNA-Binding Proteins/metabolism , Electrophoretic Mobility Shift Assay , Female , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Humans , Mice , Microscopy, Confocal , Molecular Sequence Data , Oligonucleotides/metabolism , Protein Binding , RNA, Double-Stranded/metabolism , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino AcidABSTRACT
The physis has limited ability to undergo repair, and injury may result in growth arrest. Osteogenic protein-1 promotes bone formation in diaphyseal defects, chondrocyte proliferation, and matrix synthesis. The authors' goal was to determine if the presence of osteogenic protein-1 in a defect involving the physis would promote cartilage repair, and in doing so, to determine the effect of osteogenic protein-1 on physeal growth. An ovine model of growth plate damage was used, in which the proximal medial physis of the tibia was partially ablated. The defect was filled with a Type I collagen paste containing osteogenic protein-1 (350 microg) or collagen alone. Growth rate was measured at 4, 14, and 56 days, and the defects were analyzed histologically at 4, 14, and 56 days. Bone bridge formation occurred within the defect site. However, osteogenic protein-1 promoted outgrowth of the adjacent physeal cartilage. The physeal cartilage underwent expansion until the mineral forming within the defect site blocked its progress. The effect was localized because only that portion of the physis at the defect margin appeared to be affected.
