Tiny RNA molecules control embryo development, stress response studies show
Researchers studying fruit fly embryos found that small RNA molecules act as master switches controlling how genes activate during early development. The discovery reveals how environmental stress disrupts this process, offering potential insights into birth defects and developmental disorders that could inform medical research and therapeutic approaches.
Originaltitel: Small non-coding RNA in early fly development: plasticity, interactions and improved bioinformatic tools
<p>At fertilization, the male and female pronuclei undergo a transformation from germline to pluripotency as they fuse, marking the beginning of <em>Drosophila</em> embryogenesis. As the parental contributions decrease, the zygote takes control of its genome in a process called the maternal-to-zygotic transition (MZT). Several small non-coding RNAs (sncRNAs), a very large and diverse group of RNAs, have regulatory roles during this transition. This includes for example microRNAs (miRNAs) and piwi-interacting RNAs (piRNAs). Regulation by miRNAs mainly occurs through mediating maternal mRNA degradation, while piRNAs operate by repressing transposable elements (TEs) and regulating the nanos-induced embryonic body axis determination.</p><p>In this thesis, the complex and dynamic field of early <em>Drosophila</em> embryogenesis and sncRNAs are put in relation to the included papers. In Paper I, I explored the most stress-sensitive embryonic period and found that stress before the midblastula transition retains maternal miRNAs. These miRNAs impact zygotic gene activation by modulating the boundary factor Elba1, leading to compromised transcription control. Paper III examines the piRNA population during MZT. I find differences of unique piRNA sequences in embryos of different ages but not in target preferences, potentially highlighting the importance of constant repression of certain TEs. Paper II addresses specific difficulties with sncRNA seq data analysis and presents a bioinformatic framework to improve these analyses using a sequence-based strategy.</p><p>This thesis highlights the intricate interplay of sncRNAs in the critical period of early <em>Drosophila</em> embryogenesis and offers insights into their regulatory roles.</p>