Volume : 5, Issue : 2, February - 2016

Characterization of rat and human c-MYC gene expression

Takuma Hayashi

Abstract :

<p>&nbsp;Rat genomic regions covering cellular myelocytomatosis oncogene (c-MYC) were cloned from the DNA of both normal liver and two lines of Morris hepatomas, one of which had c-MYC amplification. The three restriction maps showed perfect agreement within the overlapping regions. The 7 kilo base pair (kbp) regions, which included the entire normal rat c-MYC and the region 2.2 kbp upstream, and one from the hepatomas, were sequenced and found to be identical. The coding regions of exons 2 and 3 were highly conserved between rat, mouse and human, but some differences in amino acids of c-MYC were noted. Exon 1 and the noncoding region of exon 3 showed limited homology between the three species. Rat exon 1 contained several nonsense codons in each frame and no ATG initiation codon, indicating there to be no coding capacity in this exon. The 2.2 kbp upstream regions and the introns compared showed unusual conservation between the rat and human c-MYC genes. Some motifs, previously proposed as having a functional role in human c-MYC, were also found in equivalent positions of the rat sequence. S1 Nuclease protection mapping revealed the second promoter of c-MYC gene to be preferentially used in most tissues or in hepatoma cells, and the second poly A addition signal to be the only one functional in all the c-MYC mRNA sources examined</p>