Craig Mello is an American molecular biologist known for his foundational work on RNA interference, a natural mechanism cells use to silence genes. He is a professor of molecular medicine at the University of Massachusetts Medical School and has been a long‑time investigator with the Howard Hughes Medical Institute. His research helped establish new experimental and therapeutic approaches to control gene expression.

Discovery of RNA interference

Mello and his colleague Andrew Fire reported in the late 1990s that double‑stranded RNA triggers sequence‑specific suppression of matching messenger RNA molecules in the roundworm Caenorhabditis elegans. This phenomenon, known as RNA interference, revealed a conserved cellular pathway in which small RNA molecules guide protein complexes to degrade or block target RNAs. Their work transformed the understanding of how genes can be regulated after transcription and provided a versatile tool for genetic analysis.

Career and scientific approach

Trained in molecular biology, Mello has led laboratories that integrate genetics, biochemistry and cell biology to investigate how RNA molecules control development and cellular responses. He has supervised graduate students and postdoctoral researchers and collaborated broadly to translate mechanistic insights into widely used research methods. His institutional roles include faculty appointments and contributions to scientific education.

Importance and applications

The discovery of RNA interference rapidly altered laboratory practice: researchers use small interfering RNAs (siRNAs) and related reagents to silence specific genes in many organisms. Beyond basic research, RNAi principles underpin efforts in biotechnology and medicine, including the design of nucleic‑acid therapies and strategies to modulate disease‑related genes. Practical challenges such as delivery, specificity and immune responses have become active areas of development.

Recognition and legacy

For elucidating RNA interference, Mello and Fire shared the 2006 Nobel Prize in Physiology or Medicine. The finding is regarded as a major milestone in molecular genetics, opening new paths for exploring gene function and for developing molecular therapeutics. For further reading on his work and contributions to science policy and education, see profiles and institutional pages linked above.