U.S. Department of Health and Human Services
Katherine McJunkin

 Contact Info

Tel: 301-496-6991
Email: katherine.mcjunkin@nih.gov

 Select Experience

  • Postdoctoral FellowUniversity of Massachusetts Medical School2011-2017
  • Ph.D.Watson School at Cold Spring Harbor Laboratory2010
  • B.A.Princeton University2005

 Related Links


Katherine McJunkin, Ph.D., Stadtman Tenure-Track Investigator

Acting Section Chief, Section of Regulatory RNAsLaboratory of Cellular and Developmental Biology
  • Developmental Biology
  • Genetics/Genomics
  • Molecular Biology/Biochemistry
Research Summary/In Plain Language

Research in Plain Language

The basic principle of molecular biology is that a unit of DNA (a gene) is transcribed into a messenger RNA (mRNA), which is then translated into a functional protein (such as an enzyme, or a structural piece of the cell membrane). In the last two decades, many new layers of complexity have emerged to add to this picture. MicroRNAs are a recently-discovered class of molecule: tiny RNAs which antagonize the conversion of mRNAs to protein, a process known as "gene silencing." In normal cells, microRNAs are one critical layer in the careful control of protein levels. Therefore, not surprisingly, mutations which result in abnormally elevated or decreased amounts of microRNAs perturb the cellular processes regulated by mRNAs, and can lead to cancer. In fact, changes in microRNA levels have been observed in almost every type of cancer, including pancreatic, breast, lung, leukemia, sarcoma, lymphoma, ovarian, kidney, liver, prostate, and others. Moreover, perturbation of microRNA levels can play a role in every stage of disease, from initiation to invasion to metastasis.

Our work aims to elucidate the basic biology which controls microRNA levels. The amount of microRNA at a given time is a result of the balance of the rate at which microRNAs are made and the rate at which they are degraded. Although many studies have addressed how microRNAs are made, we understand very little about how they are degraded. We have designed multiple experiments which come from different angles to discover the factors that control microRNA degradation.

The very exciting news is that restoring normal microRNA levels has had astounding therapeutic effects on cancer in mice, and many research groups and companies are exploring related treatments in humans. One method of restoring normal microRNA levels is to directly deliver modified microRNAs to tumors; however, the pharmacology of these molecules is not ideal. We propose that microRNA degradation could be targeted as an alternative means to restoring microRNA levels. This is an attractive strategy because microRNAs are likely to be degraded by enzymes, which can be inhibited by traditional small-molecule drugs. Thus, learning about the mechanism of microRNA turnover will both deepen our understanding  of cancer biology, as well as potentially open up a novel therapeutic avenue.