Bovine DNase I: gene organization, mRNA expression, and changes in the topological distribution of the protein during apoptosis in lens epithelial cells.
Genomic DNA sequencing and alignment with the known DNase I mRNA showed that the bovine gene consists of 9 exons and that only the last 8 encode the protein, since initial ATG was found at exon II. RT-PCR was used to identify DNase I mRNA in lens epithelium in vivo and in cultured epithelial cells. We found DNase I transcripts having the same nucleotide sequence as the pancreas form and others lacking almost all exon V. The lens protein presented a slightly higher relative molecular weight than the pancreatic enzyme. Lens DNase I was located in secretory pathway organelles and excluded from the nucleus. Nevertheless, in apoptotic lens epithelial cells in vitro, DNase I translocated to the nucleus and co-localized with TUNEL positive chromatin aggregates. These results indicate that cells in the lens epithelium constitutively express DNase I, and suggest a direct involvement of this nuclease in the final phases of chromatin degradation.
De María
Alicia
A
Laboratorio de Cultivo de Tejidos, Sección Biología Celular, Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Arruti
Cristina
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D003850:Deoxyribonuclease I / Q000235:genetics* / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007908:Lens, Crystalline / Q000187:drug effects / Q000201:enzymology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D019311:Staurosporine; D014018:Tissue Distribution / Q000187:drug effects
D012333:RNA, Messenger; D003850:Deoxyribonuclease I; D019311:Staurosporine