QUANTIFICATION AND REGULATION OF MESSENGER-RNAS ENCODING BEADED FILAMENT PROTEINS IN THE CHICK LENS

Purpose. To quantify the expression of beaded filament protein mRNA le vels in regions of the chick lens and to examine the in vitro regulati on of message and protein levels using cell culture techniques. Method s. RNase protection assays and Northern blotting were used to quantify beaded filament protein mRNA levels in dissected lenses. Cultured cel ls were assayed for mRNA with RNase protection and for protein with We stern blotting and ELISA techniques after treatment with cAMP analogs. Results. Beaded filament protein message levels were greatly up-regul ated in cortical fiber cells compared to annular pad cells. Full lengt h messages were also detected in nuclear fiber cells. The presence of an unusual form of the CP49 message with a lamin-like insert. CP49(INS ), was also established. Both message and protein levels were subject to regulation in response to elevated intracellular cAMP levels. Concl usions. The accumulation of beaded filament protein levels during fibe r cell development may be due to the increased cAMP-mediated transcrip tion of message, The presence of CP49(INS) may lend new insight into m echanisms of intermediate filament assembly.