AUTONOMOUS REPLICATION ACTIVITY OF A HUMAN MITOCHONDRIAL-DNA SEQUENCEINSERTED INTO GENOMIC DNA

Mitochondrial DNA (mtDNA) fragments can be found inserted into nuclear DNA and may contribute to cancer and aging. A HeLaTG-cell nuclear tra nscript was shown to include human cytochrome oxidase subunit 3 (coxII I) mtDNA fused to c-myc sequences. Independently, a coxIII-containing cDNA was discovered to replicate autonomously in HeLa cells. We show t hat the HeLaTG mtDNA insertion has autonomous replication activity whe n transfected into HeLa cells and in a mammalian in vitro replication system. Replication in vitro starts within the fusion cDNA sequence. I nsertion of an element which could function as a replication origin ma y affect cellular DNA replication and proliferation.