Abstract
Purpose: :
We have previously reported the presence of CPEB, migrating as two putative bands between 60 - 80 kDa and localizing to the retinal pigment/supportive cell layer in dark- and light-adapted octopus retinas. CPEBs are trans-acting elements known to bind the CPE consensus sequence, U4-5A1-3U, located within the 3’ UTRs of mRNA, resulting in temporal regulation of translational repression and activation (Mendez and Richter, 2001; Stebbins-Boaz et al., 1999; Cao and Richter, 2002). We believe that the differential expression of α-tubulin and S-crystallin mRNA previously detected in dark- and light- adapted octopus retinas may result from CPE-dependent mRNA masking and unmasking. If masking and unmasking of these mRNAs does occur, then regulatory elements or sequences should be present in their 3’ UTRs. Here we investigate the presence of CPEs in α-tubulin and S-crystallin mRNA isolated from light- and dark-adapted octopus retinas.
Methods: :
3’-RACE and sequencing was used to isolate and analyze the 3’ UTRs of α-tubulin and S-crystallin mRNA.
Results: :
The following CPE-like sequences in the 3’ UTR of isolated 326-bp S-crystallin A and B variants: UUUAACA, UUUUUAA, and UUUUA. No CPE or CPE-like sequences were detected in the 3’ UTRs of α-tubulin mRNA.
Conclusions: :
The detection of CPEB and the identification of the putative CPE-like sequences in the S-crystallin 3’ UTR suggest that CPEB may be involved in the activation of masked S-crystallin mRNA, but not in the regulation of α-tubulin mRNA, resulting in increased S-crystallin protein synthesis in dark-adapted octopus retinas.
Keywords: gene/expression • retina • transcription