Localization of two conserved cis -acting enhancer regions for the filensin gene promoter that direct lens-specific expression.
Filensin is a unique eye lens intermediate filament protein, and a major component of 'beaded filament' cytoskeletal network. Expression is restricted to lens fiber cells and is believed to be functionally important for lens development by maintaining lens fiber cell shape conformation and lens transparency. The mouse filensin gene promoter core was identified by the promoter activity analysis and found to cover the region from -56 to +4. A reporter vector driven by the filensin promoter core was constructed and DNA fragments derived from the 5'-flanking regions of the gene were cloned into the vector to identify putative cis -acting promoter enhancing activities. The activity of these constructs was monitored by transfection into the chicken embryonic lens cell culture system. Two fragments were identified with cis -acting enhancer activity that re-conferred the lens fiber cell specific expression of the promoter. The first was a 1.7-kbp region located 7.5 kbp upstream from the transcriptional start point while a second 2.1-kbp region was found adjacent to the promoter core. Both fragments specifically directed the lens cell specific expression of only the filensin promoter and not other heterologous promoters. Comparison of 10 kbp of human and mouse 5'-upstream sequences of the filensin promoter revealed two highly conserved sequences that corresponded in their spacing to the putative enhancer regions. These studies have identified the first conserved regulatory sequences important in the lens specific regulation of the filensin gene.
Masaki
Shigeo
S
Department of Biochemistry, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, 480-0392, Japan. smasaki@inst-hsc.pref.aichi.jp
Yonezawa
Satoshi
S
Quinlan
Roy
R
D000818:Animals; D018929:Cell Culture Techniques; D002642:Chick Embryo; D017124:Conserved Sequence; D004742:Enhancer Elements, Genetic; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007381:Intermediate Filament Proteins / Q000235:genetics* / Q000378:metabolism; D007908:Lens, Crystalline / Q000196:embryology / Q000378:metabolism*; D051379:Mice; D010957:Plasmids; D011401:Promoter Regions, Genetic; D013045:Species Specificity; D014162:Transfection
D005136:Eye Proteins; D007381:Intermediate Filament Proteins; C079098:filensin