Quantification and regulation of mRNAs encoding beaded filament proteins in the chick lens.
OBJECTIVE
To quantify the expression of beaded filament protein mRNA levels in regions of the chick lens and to examine the in vitro regulation of message and protein levels using cell culture techniques.


METHODS
RNase protection assays and Northern blotting were used to quantify beaded filament protein mRNA levels in dissected lenses. Cultured cells were assayed for mRNA with RNase protection and for protein with Western blotting and ELISA techniques after treatment with cAMP analogs.


RESULTS
Beaded filament protein message levels were greatly up-regulated in cortical fiber cells compared to annular pad cells. Full length messages were also detected in nuclear fiber cells. The presence of an unusual form of the CP49 message with a lamin-like insert, CP49INS, was also established. Both message and protein levels were subject to regulation in response to elevated intracellular cAMP levels.


CONCLUSIONS
The accumulation of beaded filament protein levels during fiber cell development may be due to the increased cAMP-mediated transcription of message. The presence of CP49INS may lend new insight into mechanisms of intermediate filament assembly.
Ireland
M E
ME
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Goebel
D J
DJ
Maisel
H
H
Kiner
D
D
Poosch
M S
MS
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D002645:Chickens; D000242:Cyclic AMP / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism*; D007908:Lens, Crystalline / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D015854:Up-Regulation
D005136:Eye Proteins; D007381:Intermediate Filament Proteins; D012333:RNA, Messenger; D000242:Cyclic AMP