UMD Study Uncovers Germ Cell Findings with Implications for Disease Research

A UMD-led, multi-institution team of researchers has discovered new mechanisms that dictate the development of germline cells — precursor stem cells that become either eggs or sperm depending on whether they end up in ovaries or testes. Their findings ultimately could help advance research to combat cancers, viral diseases, male infertility and other health issues.

Stem cells, types of undifferentiated cells that have the ability to develop, or differentiate, into specific cell types such as egg, sperm, muscle or nerve cells, are at the forefront of new knowledge for understanding and fighting diseases. However, the mechanisms by which stem cells, and particularly germ cells, differentiate are still incompletely understood. Germ cells are the only cell type capable of passing genetic information on to the next generation.

Published in Stem Cell Reports, the new study examined in chicken germ cells, mechanisms that factor into germ cell development and gene expression. In particular, it looked at DNA methylation, an essential mechanism for environmental (epigenetic) impacts on cell differentiation. UMD Professor Jiuzhou Song, Ph.D., department of animal and avian sciences, College of Agriculture and Natural Resources, and colleagues uncovered DNA methylation patterns associated with genes responsible for cancers and viral infections.

Also discovered were markers in chickens used to identify male germ cells, uncovering how environmental factors—epigenetics—affect these cells and providing significant insight into causes of and possible treatments for, male infertility in animals, including humans. These findings unlock possibilities for future animal and human health research in these areas, and also set the stage for chickens as a more prominent model organism for stem cell research.

Stem cell research has applications for treating cancer, heart disease, neurological disorders like Alzheimer’s disease, diabetes, and even injuries. These cells can replicate and replace damaged tissue, so understanding their development is important to the future of this work. Epigenetic factors that affect the way genes are expressed, can also play a large role in cell and tissue development, and no studies have previously looked at the mechanisms at play in germline stem cell development and how epigenetics play a role.

“From genome to phenome as it is called is a very complicated process for different gene networks to create the trait you see in an animal or human. The activity of key genes is the same or similar in common cell types, but the activity of other genes may differ completely among species, especially for the roles of stem cells,” explained Professor Songs. “Looking at these mechanisms helps to decode genes, understand complex traits, and develop future treatment plans to better understand animal and human health.”

The epigenetic markers identified in this study are unique to chickens, which are an up-and-coming animal model that is in many ways ideal for the study of epigenetics, stem cells, and developmental research.

“Most people still think of mice when they think of animal models that support animal and human health research. But regulatory elements are quite similar between the chicken and human genome. In fact, the genetic similarity between a human and a chicken is about 60%. The development of chickens is rapid, easy to see, and easy to manipulate, making them very unique compared to other animal models. They are ideal for developmental and stem cell research because you can easily observe egg growth and the development process in real time,” says Song.

Song said he is devoted to this animal genetics work, with its connections to human health in mind, but is also thinking about the broiler chicken industry and overall animal welfare. “This work provides a deeper understanding of developmental mechanisms in chickens that lead to healthier chickens and humans,” said Song. “The applications and need for epigenetic stem cell research is great, and chickens are a great model for this work.”