Detection of IAP related transcripts in normal and transformed rat cells

Intracisternal A-particles (IAP) genes in variable copy number exist in all rodent species studied. Expression is highly repressed in murine normal cells except in embryonic and transformed cells. We searched for IAP related sequences expression in another rodent species cells. Using the more conserved sequence of IAP gene between mouse, Syrian hamster, and rat species (0.4 kb HindIII-PstI fragment from PMIA14), we have been able to detect IAP related transcripts in rat cells. We found that, i) IAP related transcripts are poorly expressed in normal cells, since among 10 tissues tested, only the placenta shows IAP RNA. ii) IAPs are highly expressed in all the transformed cells tested. iii) the detected transcripts appear to have similar sizes in rat cells as in mouse cells (7.2 kb; 5.4 kb). None of the probes corresponding to other regions of the IAP gene nor the entire sequence of PMIA14 allowed us to detect such transcripts.