Promoted to Investigator
Paul Trainor studies craniofacial pathologies that emerge from defects in the neural crest, a population of embryonic cells that migrate extensively during development and give rise to many different tissues, including most of the bone and cartilage of the head skeleton.
In pioneering work, he and his team discovered that Treacher Collins syndrome, which is marked by severe jaw, palate and ear defects, is caused by the premature death of neural stem cells, the precursors of neural crest cells. Without them, the embryo cannot produce enough neural crest cells to properly build the head and face. In a follow-up study they showed that blocking the p53 gene, which promotes cell death, restores neural crest cells and rescues craniofacial abnormalities in a mouse model of Treacher Collins syndrome.
In a systematic search for novel genes regulating cranial crest development, Trainor’s team identified and characterized several novel mouse mutants showing differing craniofacial anomalies. Interestingly, one of the implicated genes encodes an enzyme involved in vitamin A metabolism, which needs to be tightly controlled since both deficiencies in vitamin A as well as an excess of vitamin A can cause severe birth defects.
Promoted to Investigator
Peter Baumann’s primary research interest focuses on learning how the natural ends of chromosomes, known as telomeres, are maintained. Specifically, he wants to know how telomeres, which look just like broken strands of DNA that a cell’s repair machinery is designed to fix, are protected from being mistakenly joined together. He discovered that a complex of two proteins keeps telomeres from being mended, which would set the stage for the development of cancer in successive generations of cells.
In related work, he isolated the long-sought RNA subunit of fission yeast telomerase, the enzyme that maintains telomeres. In studying the precursors to that subunit, he discovered an entirely new and unanticipated pathway for processing RNA, allowing him to examine how telomerase is assembled and controlled.
In completely unrelated work, Baumann discovered how all-female lizard species successfully reproduce without any males while avoiding the genetic monotony and disease vulnerability that often results from asexual reproduction. Celibate lizards maintain their genetic diversity by starting with twice the number of chromosomes and swapping information between identical sister chromosomes rather than lining up one set from each parent as sexual species do.
Promoted to Associate Investigator
Sue Jaspersen is interested in the nuclear structures required for yeast cell division. Nuclear architecture has dramatic effects on gene expression and genomic instability, and disruptions in normal nuclear organization have been linked to cancer and other diseases, making her work on yeast nuclear structure a valuable model for human conditions. Most of her work focuses on a cellular component known as the spindle pole body, which forms the mitotic spindle apparatus that helps pull the chromosomes apart. Each time a cell divides—and it takes millions of cell divisions to create a fully grown human body from a single fertilized cell—its chromosomes have to be accurately divvied up between both daughter cells.
Most recently, Jaspersen and her team discovered that a protein known as Mps3 ensures not only that cells have two functional spindle pole bodies but also that both spindle pole bodies are properly anchored in the nuclear membrane via Mps3. In earlier work, she reported that Mps3 pokes into the nuclear interior and tethers chromosome ends, known as telomeres, indicating that it governs chromosome position within the nucleus and potentially functions in silencing genomic regions adjacent to telomeres.