In:
European Journal of Biochemistry, Wiley, Vol. 268, No. 22 ( 2001-11-15), p. 5920-5929
Abstract:
The present study examines novel mechanisms that regulate levels of the RIα subunit of cAMP‐dependent protein kinase. We found that RIα protein is induced threefold by 8‐(4‐chlorophenyl)thio‐cAMP in hormone responsive rat Sertoli cells, while total RIα mRNA is not correspondingly induced. Two RIα mRNA isoforms with different 5′ untranslated sequences ( RIα1a and RIα1b ) are produced from the RIα gene in Sertoli cells. Deletion/mutation analysis of the cAMP‐response‐element‐containing promoter upstream of the RIα exon 1b revealed that while mutation of the cAMP response element had no effects on cAMP‐mediated induction, a 73‐bp region of the RIα exon 1b itself conferred a fivefold to eightfold induction of reporter activity to homologous and heterologous promoters. The responsiveness of this region was dependent on a sense orientation downstream of the promoter start sites and had no effect on reporter mRNA, indicating that the cAMP‐mediated induction occurs at the post‐transcriptional level. Modeling of the RIα1b 5′ UTR secondary structure revealed a 5′ CAP‐proximal, strong stem‐loop presenting an element similar to multiple start‐site element downstream‐1 (GCTCGG) in the loop region. RNA‐EMSAs performed with the labeled RIα1b 5′ UTR showed stabilization of a protein/RNA complex in extracts from 8‐(4‐chlorophenyl)thio‐cAMP stimulated Sertoli cells. This complex was abolished by mutation of the multiple start‐site element downstream‐1‐like element. Our findings indicate that there is a cAMP‐mediated induction of RIα expression at the post‐transcriptional level, dependent on the 5′ UTR of RIα1b mRNA.
Type of Medium:
Online Resource
ISSN:
0014-2956
,
1432-1033
DOI:
10.1046/j.0014-2956.2001.02542.x
Language:
English
Publisher:
Wiley
Publication Date:
2001
detail.hit.zdb_id:
1398347-7
detail.hit.zdb_id:
1464377-7
SSG:
12
