Role of MED1 (MBD4) Gene in DNA repair and human cancer
Article first published online: 27 FEB 2001
Copyright © 2001 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 187, Issue 2, pages 137–144, May 2001
How to Cite
Bellacosa, A. (2001), Role of MED1 (MBD4) Gene in DNA repair and human cancer. J. Cell. Physiol., 187: 137–144. doi: 10.1002/jcp.1064
- Issue published online: 20 MAR 2001
- Article first published online: 27 FEB 2001
- Manuscript Received: 30 NOV 2000
- Manuscript Accepted: 30 NOV 2000
- U.S. Public Health Service. Grant Numbers: CA78412, CA06927
- Commonwealth of Pennsylvania
The human protein MED1, also known as MBD4, was isolated in a yeast two-hybrid screening as an interactor of the mismatch repair protein MLH1. MED1 contains an N-terminal 5-methylcytosine binding domain (MBD), which allows binding to methylated DNA, and a C-terminal catalytic domain with homology to bacterial DNA damage-specific glycosylases/lyases. This suggests that DNA methylation may play a role in human DNA repair. MED1 acts as a mismatch-specific DNA N-glycosylase active on thymine, uracil, 5-fluorouracil and, weakly, 3,N4-ethenocytosine paired with guanine. The glycosylase activity of MED1 prefers substrates in which the G:T mismatch is present in the context of methylated or unmethylated CpG sites. Since G:T mismatches can originate via spontaneous deamination of 5-methylcytosine to thymine, MED1 appears to act as a caretaker of genomic fidelity at CpG sites. Mutagenesis caused by these deamination events is a frequent mechanism of genetic instability in cancer; thus, based on the biochemical activity of its gene product, MED1 is a candidate tumor suppressor gene. Indeed, frameshift mutations of the MED1 gene have been reported in human colorectal, gastric, endometrial, and pancreatic cancer. In the future, efforts should be directed toward investigations of the functional role of the MED1 gene in the pathogenesis, prevention, and treatment of human cancer. © 2001 Wiley-Liss, Inc.