On July 5th, 2017, Dr. Mofang Liu from Shanghai Institute of Biochemistry and Cell Biology, invited by Prof. Ruiming Xu, visited IBP and gave a BEI Shizhang lecture entitled Functions and mechanism of PIWI/piRNA in spermatogenesis and male infertility.
Noncoding RNAs, widely exist in bacteria, viruses, plants and animals, play an important role in gene regulation. Expression of vital genes that function in many different biological processes is tightly regulated by noncoding RNAs at post-transcriptional, RNA editing or translational levels. MiRNAs, siRNAs, piRNAs are three representative classes of small noncoding RNAs. Deregulation of them or their association protein factors are usually related to diseases. So it is a research hotspot on the functions and mechanisms of the small noncoding RNAs.
Dr. Mofang Liu’s lab focuses on studying the functions and mechanisms of small noncoding RNAs in diseases development. Their recent amazing work showed that PIWI/piRNA, which are exclusively expressed in germ cells, are responsible for promoting histone-to-protamine exchange in spermatogenesis. In mouse model, piRNA promotes ubiquitylation and clearance of MIWI (mouse PIWI) at late stage of spermatogenesis.
By gene sequencing of the D-box region (E3 ligase recognition motif) of HIWI (human PIWI) from 413 Idiopathic azoospermia patients, they found three types of mutations that impaired ubiquitylation of HIWI protein. Further studies uncovered the detailed mechanism of how aberrant retention of HIWI affects spermatogenesis. This may provide a new clue for male infertility diagnosis.
In additional to the presentation, students and scientists discussed freely with Dr. Mofang Liu and benefit a lot.