JABSOM Awarded NIH Grant to Investigate the Role of a Key Gene in Male Reproduction

The University of Hawaiʻi received a $2,438,717 grant from the National Institutes of Health (NIH) to examine the role of a key gene in male reproduction. The award, which is administered by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, will support a five-year research project led by Monika Ward, PhD, Professor in the John A. Burns School of Medicine’s (JABSOM) Department of Anatomy, Biochemistry & Physiology (ABP).

Ward will investigate how the Zfy gene affects male reproduction, specifically through the regulation of male fertility and the production of sperm in mouse models. Fertility remains a pressing issue in medicine and Ward hopes this research project helps advance the collective understanding of how these genetic regulation processes affect fertility in humans.  

“The Zfy gene is an essential male fertility factor but how it imposes its important role has not been established,” Ward said. “If we want to overcome the overarching issue of infertility, we must have a deep understanding of the processes that underlie fertility.”

This is not the first time that the research community has been excited to investigate the Zfy gene but it disappeared from the spotlight for a couple of decades, Ward explains. About 30 years ago, researchers were exploring its potential connection to determining the sex of animals but when it was found that it wasn’t a sex-determining gene, it slipped off the radar and didn’t receive much attention for years.

“The Zfy gene is a forgotten hero. No one really talked about it for two decades, until small evidence started emerging that it may be linked to fertility,” said Ward. “And since its reemergence in 2010, multiple reports, including several from our lab, supported the roles of this gene in male reproduction.”

As the Zfy gene reemerged on the scene, it became clear to Ward and other researchers that this gene could play an important role in male fertility and Ward’s new research project aims to learn more about exactly what that role is.

Ward will investigate the molecular function of the Zfy through looking at gene expression and fertility in mouse models. The mouse Y chromosome actually has two Zfy gene copies, Zfy1 and Zfy2, and both have the potential to affect sperm-producing cells and fertility but it’s not clear exactly how they influence these processes..

Researchers know that when both Zfy genes are absent in mice, there’s a very strong effect on fertility, Ward explains.

“When both Zfy1 and Zfy2 are missing, the mice are completely infertile,” she said. “And if they do produce sperm, they are terribly misshaped and do not swim well.”

But when just one Zfy gene is missing, the effect is more moderate and there’s greater uncertainty about the full consequences of that gene loss. To dig into this, Ward’s lab will look at how the absence of each Zfy gene, separately, affects the expression of other genes in the testes.

“We want to better understand the molecular mechanism that underpins the important roles of Zfy1 and Zfy2,” she said. “We want to fill this gap in knowledge and define how Zfy regulates sperm production and function.”

The researchers will examine how the presence and absence of the Zfy1 and Zfy2 genes changes the expression of other genes in the testes. This research will help determine how the Zfy gene directly and indirectly regulates the gene expression that affects fertility and sperm production.

They will also aim to better understand the mechanisms that drive the Zfy gene’s influence of gene expression. Ward’s hypothesis is that the ZFY protein is an essential regulator of fertility and sperm production. She suspects ZFY1 and ZFY2 are changing these processes by binding to specific places in the DNA. She hopes this research sheds light on whether this is the case – or points her lab in another promising direction.

“My top goal in this research project is to characterize the consequences of the loss of Zfy genes on gene expression in different types of germ cells in the testes,” said Ward. “And my second goal is to see how ZFY protein is regulating these genes – whether that’s through direct binding to the DNA or through binding to other proteins that work in concert with this process. Or, through something else entirely that our findings suggest holds importance.”

“This could lead to a whole new line of research.”

To investigate whether the ZFY protein is binding to the DNA, Ward’s lab will utilize a technique that allows for this binding to transpire in mouse models where genes are expressed. This involves generating a set of mice that have special tags added to Zfy genes that enable isolating ZFY proteins to examine whether they bind to the DNA, as predicted. If tagged ZFY is binding to the DNA, the researchers will zoom in on which parts of the DNA it’s binding to so they can identify the pieces of DNA are connected to gene regulation in fertility.

The mouse models are a crucial piece of the puzzle in this research project. And Ward was well-positioned to pursue this work because her lab is highly accomplished in producing the mouse models that are required for this kind of science.

When the mouse is infertile, it can’t be easily reproduced. But, Ward’s lab is skilled at efficiently propagating infertile and subfertile mouse models through assisted reproduction. Only a handful of researchers around the world are able to perform this technique, she explains, but it’s highly beneficial in this research realm because it allows her lab to generate the necessary amount of tissue and cells to study.

“Assisted reproduction skills are hugely beneficial for many research projects across infertility,” she explained. “Honing this technique has empowered us to obtain some of the rare and essential testicular cells that we need for our molecular analysis of ZFY and its impact on fertility.”

For this project, her lab generated different types of mice including ones lacking Zfy1, ones lacking Zfy2, and a type lacking both Zfy genes. They also developed mice with tagged ZFY1 and ZFY2 proteins.

Ward has been studying reproductive and developmental biology and genetics of male infertility for almost 30 years and is excited about how this project could contribute to the field. She believed it could help advance knowledge surrounding an important gene for fertility – and other components of human health.

“The findings will impact our understanding of how mouse Zfy regulates sperm production and will provide vital insights into the role of how the human ZFY is connected to mechanisms underlying human male infertility,” she said.