Xiaoyu Zhang, Ph.D.

Professional Background

I obtained my PhD degree from the Nanjing Agricultural University in China. During my PhD training, I studied extrinsic and intrinsic regulators of germline stem cells in mice. Upon graduation in August 2018, I joined Dr. Ning Wang’s lab at the University of Kansas Medical Center to continue my studies in germline stem cell biology as a postdoctoral fellow, and in 2021, I was promoted as an Research Assistant Professor.

• PhD, Germline stem cell biology, Nanjing Agricultural University, China
• Post Doctoral Fellowship, Germline stem cell biology

Research

Overview

Poor sperm quality and low sperm counts are major causes of male infertility, which affects ~7% of all men worldwide. Meiosis is essential for haploid sperm formation and fertility. To initiate meiosis, germ cells must activate meiotic gene programs critical for the chromosomal events that occur during meiotic prophase. However, the underlying mechanisms of meiotic initiation remain elusive. While retinoic acid (RA) and its target STRA8 are necessary for meiotic initiation, they are not sufficient. The lack of knowledge of additional stimuli required to initiate meiosis represents a significant gap in our knowledge of meiosis and spermatogenesis as well as a roadblock to recapitulate meiosis and derive haploid sperm in vitro, a technique which could have tremendous value in research and reproductive medicine. Our new data in primary mouse spermatogonial stem cell (SSC) culture suggest that nutrient restriction, an inducer of yeast meiosis, in combination with RA is sufficient to induce meiosis in vitro. Notably, meiosis induced by nutrient restriction and RA recapitulates the transcriptomic and cytologic features of meiosis in vivo. Based on this finding, we hypothesize that nutrient restriction and retinoic acid synergize to induce meiotic initiation that support in vitro haploid sperm production. In addition to defining the precise nutrient changes sufficient to induce meiotic initiation, Our study will lead to the development of a refined system that supports both meiotic initiation and progression in vitro. By identifying nutrient-sensing pathway that works in conjunction with RA, our study opens a new dimension in our understanding of how meiotic initiation occurs in mammalian germ cells. This novel information will expand our knowledge of mammalian meiosis and spermatogenesis at both tissue and molecular levels as well as advance the technology to produce haploid germ cells in vitro.