Xin Zhiguo Li, Ph.D.

Our lab studies epigenetic inheritance. DNA is not the only information carrier. Epigenetic information carried by RNA, DNA methylation, histone codes, or three-dimensional nuclear structures also affects individual phenotypes. These epigenetic markers change with age, lifestyle, and environmental exposure. The claim that acquired traits are heritable, known as "Lamarckian" inheritance, once discredited, has been resurrected by recent advances in our understanding of epigenetics. Plant small RNAs have been shown to provide the sequence specificity to establish and maintain epigenetic status across generations, the exact counterpart in animal has not been found. We strive to understand how various germ-line RNAs prepare and shape epigenetic information flowing across generations.

We are adopting an interdisciplinary approach that includes genetics, epigenetics, RNA biochemistry, reproductive biology, early embryology, and bioinformatics, and testing our findings across different model organisms including mammals and birds. Currently, our ongoing projects are centering on piRNA regulation in germ cells. Piwi-interacting RNA (piRNA) is a group of small non-coding RNAs that are highly expressed in the germ line and are essential for human fertility. In addition to piRNAs that protect the germ-line genome from transposon activation, mammals and avian produce a distinct and abundant set of non-repetitive piRNA sequences whose function is unknown. We want to understand: 1) how piRNAs are produced? 2) How do piRNA functions? 3) How are new piRNAs originated during evolution?