|It’s in the Packaging
New recruit unravels how reproductive potential is switched on
Assoc. Prof. Philippa Melamed
Assoc. Prof. Philippa Melamed is exploring how reproductive hormones are regulated. “We need to understand the basic biology in order to understand the many problems that can arise in the ability to reproduce,” she says. “I like puzzles. I’m interested in the way in which the packaging of the DNA and its accessibility at particular genes changes in response to the regulatory hormones.”
Her research belongs to the burgeoning field known as epigenetics, and hers is the only group currently working on the packaging of the genes encoding the pivotal reproductive hormones into chromatin, the combination of DNA and proteins that makes up chromosomes.
Melamed was born in the U.K. and immigrated to Israel in 1987 where she completed all her academic degrees. After a postdoctorate period in Toronto followed by a tenured position at the National University of Singapore, she then returned to Israel with her family and joined Technion’s Faculty of Biology in 2008. She says that she knew of Technion’s reputation and its stand on the importance of doing interdisciplinary research in life sciences, engineering and physics, and the fact that Technion was investing resources in bio facilities. “I was very impressed with the atmosphere and the energy of the place,” Melamed says of her first visit to the institute.
Today, Melamed is mentoring a graduate student who came with her from Singapore as well as two other Israeli PhD students. Her research group is working to uncover the ways in which the regulatory hormone, GnRH, produced by the hypothalamus in the brain, stimulates changes in chromatin structure to allow production of the reproductive hormones, FSH and LH, that are found in virtually all vertebrates. “This is how reproductive potential is switched on,” she explains. The appropriate release of GnRH, which is directed in different species by various physiological and environmental cues, triggers synthesis of the LH and FSH hormones, involving unwinding of the chromatin at this part of the genome. “Although LH and FSH can be produced at extremely low levels for many years, this does not detract from their ability to be reactivated, following the appropriate stimulus,” Melamed says.
Epigenetics is a broad area of study central to understanding many basic biological processes. It focuses on examining mechanisms through which levels of gene expression can be altered long-term without changes in the DNA sequence. This growing field is changing the way researchers think about heredity.
Chromatin is the combination of DNA and proteins that makes up chromosomes. Its functions are to package DNA to enable it to fit in the cell and to serve as a mechanism to facilitate the control of gene expression and DNA replication.
GnRH, or gonadotropin-releasing hormone, is made in the brain by the hypothalamus. It causes the pituitary gland to make luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which travel via the circulation to the ovaries and testis and regulate reproduction.