Analysis of non-crystallin lens fiber cell gene expression in c-Maf -/- mice.
OBJECTIVE
To examine the role of the c-Maf transcription factor in the regulation of non-crystallin lens fiber cell specific gene expression.


METHODS
Expression of lens fiber cell genes in c-Maf null mice was analyzed by immunohistochemical and RT-PCR methods. In addition, the effect of c-Maf on fiber cell gene promoter fragments was examined in co-transfection experiments.


RESULTS
Examination of protein expression in c-Maf homozygous mutant mice revealed undetectable levels of CP49, CP115 and MIP protein. mRNA transcripts for these non-crystallin genes were observed at reduced levels in subsequent RT-PCR experiments. The co-transfection of a c-Maf expression construct with reporter constructs containing the proximal promoters of the CP49 and CP115 genes, the structural components of the lens fiber cell beaded filament, did not result in activation of reporter gene expression, as was observed with a crystallin promoter.


CONCLUSIONS
While c-Maf has been shown to play a critical role in lens specific expression of the numerous crystallin genes, it does not appear to regulate some non-crystallin fiber cell genes in the same manner. In contrast to most crystallin genes, detectable levels of CP49, CP115, and MIP transcripts are achieved in the absence of c-Maf. In co-transfection experiments, the CP49 and CP115 proximal promoter sequences were not activated by c-Maf. This suggests that increases in transcription of non-crystallin lens fiber cell genes can be enacted in a c-Maf independent fashion.
DePianto
Daryle J
DJ
Department of Cell Biology Human Anatomy, School of Medicine, University of California, Davis 95616, USA.
Blankenship
Tom N
TN
Hess
John F
JF
FitzGerald
Paul G
PG
D000818:Animals; D020346:Aquaporins; D002454:Cell Differentiation; D046508:Culture Techniques; D004268:DNA-Binding Proteins / Q000502:physiology*; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D005822:Genetic Vectors; D005838:Genotype; D007124:Immunoenzyme Techniques; D007381:Intermediate Filament Proteins / Q000235:genetics* / Q000378:metabolism; D007908:Lens, Crystalline / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051257:Proto-Oncogene Proteins c-maf; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D020346:Aquaporins; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D007381:Intermediate Filament Proteins; C495608:Maf protein, mouse; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D051257:Proto-Oncogene Proteins c-maf; D012333:RNA, Messenger; C030328:aquaporin 0; C079098:filensin; C084808:phakinin