Transcriptional deregulation of myc inlgH/myc 6;7 translocation carrying rat immunocytomas

✍ Scribed by Dr. Håkan Axelson; Warren S. Pear; Chinmay Kumar Panda; Herve' Bazin; George Klein; Janos Sümegi

• Book ID: 102844513
• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 739 KB
• Volume: 3
• Category: Article
• ISSN: 1045-2257
• DOI: 10.1002/gcc.2870030210

✦ Synopsis

We have previously shown that the reciprocal translocation t(6;7) associated with the spontaneous immunocytoma of the Louvain rat (RIC) leads t o the juxtaposition of myc t o the IgH cluster. In I0 of I4 tumors investigated the breakpoints on the myc carrying chromosome were clustered in a I .5 kb region 5' of the intact gene, proximal t o the myc promoters. In this paper we describe the effect of the translocation on myc transcription in the RIC system. Run-on analysis showed transcriptional attenuation in the normal rat myc gene, similar t o the situation in mice and humans. The attenuation was almost completely abrogated in the three immunocytomas studied. Sequence analysis of two tumors failed t o reveal any structural changes within exon I , as found by others in Burkitt's lymphoma. We also show that the transcriptional initiation of myc mRNA is changed in the RICs. In an established line of rat fibroblasts (Rat-2). the more distal myc promoter (P2) is the preferred site of initiation. In RIC, however, only 30% of transcripts were initiated from P2. We found that 40% of the transcripts were initiated from PI and 30% from a novel promoter, designated Pla, located between PI and P2.